CA1134992A - Crosslinkable copolymer of a lactone and a polyfunctional acrylate - Google Patents
Crosslinkable copolymer of a lactone and a polyfunctional acrylateInfo
- Publication number
- CA1134992A CA1134992A CA000321670A CA321670A CA1134992A CA 1134992 A CA1134992 A CA 1134992A CA 000321670 A CA000321670 A CA 000321670A CA 321670 A CA321670 A CA 321670A CA 1134992 A CA1134992 A CA 1134992A
- Authority
- CA
- Canada
- Prior art keywords
- copolymer
- thermoplastic
- produced
- crosslinkable copolymer
- producing
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
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Classifications
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
- C08G63/00—Macromolecular compounds obtained by reactions forming a carboxylic ester link in the main chain of the macromolecule
- C08G63/02—Polyesters derived from hydroxycarboxylic acids or from polycarboxylic acids and polyhydroxy compounds
- C08G63/06—Polyesters derived from hydroxycarboxylic acids or from polycarboxylic acids and polyhydroxy compounds derived from hydroxycarboxylic acids
- C08G63/08—Lactones or lactides
-
- G—PHYSICS
- G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
- G03F—PHOTOMECHANICAL PRODUCTION OF TEXTURED OR PATTERNED SURFACES, e.g. FOR PRINTING, FOR PROCESSING OF SEMICONDUCTOR DEVICES; MATERIALS THEREFOR; ORIGINALS THEREFOR; APPARATUS SPECIALLY ADAPTED THEREFOR
- G03F7/00—Photomechanical, e.g. photolithographic, production of textured or patterned surfaces, e.g. printing surfaces; Materials therefor, e.g. comprising photoresists; Apparatus specially adapted therefor
- G03F7/004—Photosensitive materials
- G03F7/038—Macromolecular compounds which are rendered insoluble or differentially wettable
-
- G—PHYSICS
- G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
- G03F—PHOTOMECHANICAL PRODUCTION OF TEXTURED OR PATTERNED SURFACES, e.g. FOR PRINTING, FOR PROCESSING OF SEMICONDUCTOR DEVICES; MATERIALS THEREFOR; ORIGINALS THEREFOR; APPARATUS SPECIALLY ADAPTED THEREFOR
- G03F7/00—Photomechanical, e.g. photolithographic, production of textured or patterned surfaces, e.g. printing surfaces; Materials therefor, e.g. comprising photoresists; Apparatus specially adapted therefor
- G03F7/004—Photosensitive materials
- G03F7/038—Macromolecular compounds which are rendered insoluble or differentially wettable
- G03F7/0388—Macromolecular compounds which are rendered insoluble or differentially wettable with ethylenic or acetylenic bands in the side chains of the photopolymer
Abstract
ABSTRACT OF THE DISCLOSURE
Theremoplastic, crosslinkable copolymer is produced by reacting an active-hydrogen containing initiator with a lacatone monomer, such as epsilon-caprolactone, and a polyfunctional acrylate, such as neopentyl glycol diacrylate. The copolymer can be crosslinked by exposure to ionizing or actinic radiation or by free-radical peroxide catalysts. The degree of crosslinking can be controlled to produce a material which is thermoplastically processable and displays modified processable than the corresponding lactone homopolymer.
Theremoplastic, crosslinkable copolymer is produced by reacting an active-hydrogen containing initiator with a lacatone monomer, such as epsilon-caprolactone, and a polyfunctional acrylate, such as neopentyl glycol diacrylate. The copolymer can be crosslinked by exposure to ionizing or actinic radiation or by free-radical peroxide catalysts. The degree of crosslinking can be controlled to produce a material which is thermoplastically processable and displays modified processable than the corresponding lactone homopolymer.
Description
3 4 ~ ~ ~
11,350 BACKGROUND_OF I~lE INVENTION
Solid, thermoplastic polymers of lactone esters have been known in the art for some time.
U. S. 3,169,945 describes a method for producing such polymers whereby a molar excess of a lactone monomer is reacted with an active-hydrogen containing initiator that is capable, with or without the aid of a catalyst, of opening the lactone ring and adding it as an open chain without forming water of condensation. The solid polymers which can be produced by this rnethod are highly crystalline and display sharp melting points.
Typical uses of the thermoplastic polylactone polymers include their use as a material of construction for orthopedic casts, splints, and similar devices, as described in U. S. 3,~g2,023; and their use as plasti-cizers for vinyl resin compositions, as described in U. S. 3,592,877.
The rheological characteristics of the solid lactone polymers have proven to be an obstacle to their more widespread use in certain applications. The melt index of the polymers rises sharply as the temperature is increased above the melting point. Except at quite high molecular weights (i.e., reduced viscosity greater than ;
about 0.8), the polymer is difficult to extrude in sheet form, since the molten extrudate has poor dimensional stability. Costly chill roll equipment must generally be employed to reduce the ~emperature of the extruded ``
11,350 BACKGROUND_OF I~lE INVENTION
Solid, thermoplastic polymers of lactone esters have been known in the art for some time.
U. S. 3,169,945 describes a method for producing such polymers whereby a molar excess of a lactone monomer is reacted with an active-hydrogen containing initiator that is capable, with or without the aid of a catalyst, of opening the lactone ring and adding it as an open chain without forming water of condensation. The solid polymers which can be produced by this rnethod are highly crystalline and display sharp melting points.
Typical uses of the thermoplastic polylactone polymers include their use as a material of construction for orthopedic casts, splints, and similar devices, as described in U. S. 3,~g2,023; and their use as plasti-cizers for vinyl resin compositions, as described in U. S. 3,592,877.
The rheological characteristics of the solid lactone polymers have proven to be an obstacle to their more widespread use in certain applications. The melt index of the polymers rises sharply as the temperature is increased above the melting point. Except at quite high molecular weights (i.e., reduced viscosity greater than ;
about 0.8), the polymer is difficult to extrude in sheet form, since the molten extrudate has poor dimensional stability. Costly chill roll equipment must generally be employed to reduce the ~emperature of the extruded ``
- 2 -~" ~
- ~ ~ 3 4~ ~
11,350 sheet as quickly as possible upon emergence from the sheet die. In blown film applications, the extrudate usually will not form a self-supporting film bubble at reduced viscosities below about 1.5. It is very di~fi-cult to produce such high viscosity material in con-ve~tional commercial polymerization equipment.
The rheological properties of the lactone polymers have hindered their more widespread acceptance in the field of orthopedic casts, despite the fact that the casts produced from them have excellent properties, i.e. they are lightweight, tough, rigid, water and soil resistant~ and easily removed. The polymer must be hea~ed above its melting polnt in order to apply it as an orthopedic cast material. At the application temper-ature, the polymer tends to be more fl~lid than is desired and, therefore, difficult to handle and apply.
SUMMARY UF THE INVENTION
. . .
The present invention provides a novel copolymer containing a major amount of lactone monomer and a minor amount of a polyfunctional acrylate copolymerized therein.
~; The copolymer is produced under essentially the same reaction conditions which are known to polymerize the lactone alone with the active-hydrogen containing initiator, except that the polyfunctional acrylat~ is additionally present in the polymerization reaction mixture.
The thermoplastic, crosslinkable copolymers of this invention display no significant degree of ~ 11,350 crosslinking themselves - as measured by gel content - yet they are highly susceptible to crosslinking by exposure to actinic or ionizing radiation. It was quite surprising that the copolymers produced in this manner displayed these properties. On the basis o the known mechanism of lactone polymerization and the structure of the polyfunctional acrylate monomers, it would be expected either that the polyfunctional acrylate would not coreact in the polymeriza-tion reaction mixture or that, if it did react, the reaction product itself would be highly crosslinked. Yet, this was not the case. Analysis of the double bond content of the thermoplastic, crosslinkable copolymer of this invention indicated that ? where a difunctional acrylate was employed, approximately half the double bonds initially present in the difunctional acrylate monomer were consumed in the polymerization reaction, indicating reaction of at least a major portion of the difunctional acrylate. Based on solubility and melt index behavior, the thermoplastic, crosslinkable copolymers themselves show little or no evidence of crosslinking.
The thermoplastic, crosslinkable copolymers of this invention can be crosslinked by heat and free radical pe-oxide catalysts, however, we prefer to cross- ~ -link them by exposure to ionizing or actinic radiation, such as electron beam or ultraviolet radiation. The thermoplastic, crosslinkable copoIymers are remarkable in their response to actinic radiation~ In comparing the ~
,, .
2 11,350 thermoplastic copolymers of this invention with physical blends of lactone homopolymer and polyfunctional acrylate, the copolymers exhibited a much more rapid crosslinking response to electron beam irradiation, determined by measuring melt index as a function of radiation dosage.
The degree of crosslinking which is imparted to the thermoplastic, crosslink2ble copolymer is readily controllable according to the desires of the practitioner, for example, by controlling the dosage o radiation. By controlling the degree of crosslinking, one can produce a range of crosslinked copolymers which display varying rheological properties. At one end of the spectrum, one can produce a lightly crosslinked copolymer (e.g. no detectable gel in methylene dichloride at 35C.) which is processable by all the conventional thermoplastic process-ing methods, such as extrusion, yet displays melt properties which are more desirable than the corresponding lactone homopolymers of similar reduced viscosity. It is thus possible to extrude sheets of the lightly crosslinked copolymer wi~hout the use of chill roll equipment and to blow film from the crosslinked copolymer at considerably ` ~ lower reduced viscosities (i.e., molecular weights) than is possible with the corresponding lactone homopolymer. At higher levels of crosslinking, wherein the copolymer con-~ains a gel phaseg it exhibits a soft, rubbery consistency over a fairly broad temperature range. In applications ~., _ 5 ~ 11,350 such as orthopedic casts and splints, such a material is much easier to handle during the application process than the corresponding lactone homopolymer.
The thermoplastic, crosslinkable copolymers display physical and mechanical properties at room temperature which are similar to those of lactone homopolymers having considerably higher molecular weight.
BRIEF DESCRIPTION OF THE DRAWINGS
Figure 1 is a graph which plots melt index at 190C. as a function of radiation dosage of electron beam radiation for: a physical blend containing 98 weight percent of the poly-epsilon-caprolactone h~mopolymer and 2 weight percent neopentyl glycol diacrylate; the same physical blend after 4 hours at 190C., a copolymer of epsilon-caprolactone and neopentyl glycol diacrylate containing 2 weight percent neopentyl glycol diacrylate copolymerized therein; and a copolymer of epsilon-caprolactone and neo-pentyl glycol diacrylate containing 4 weight percent neo-pentyl glycol diacrylate copolymerized therein. ~- `
Figure 2 is a graph which presents a series of ~`
stiffness-temperature curves which plot 1% secant modulus as a function of temperature for three crosslinked copolymers produced by irradiating a copolymer of epsilon-caprolactone and neopentyl glycol diacrylate (2 weight percent) with doses of 2, 5, and 10 megarads of electron beam radiation.
~ ~ 3 ~ ~ 2 11,350 DETAILED DESCRIPTION OF THE INVENTION
The thermoplastic, crosslinkable copolymer of this invention is produced by reacting, at a temperature of from 25 to 300~C., an active-hydrogen containing initiator with a moLIr excess of a monomer mixture comprising:
(A) from 90 to 99.5 weight percent preferably from g5 to 99.5 weight percent of at least one lactone of the formula:
R
R-CH~ C -~ C=O
R
. ~. O
wherein n is an integer having a value of from about 3 to 6, at least n~2 of the R's are hydrogen and the . remaining R's are alkyl of up to 10 carbons; and (B) from 0.5 to 10 weight percent preferably from 0.5 to 5 weight percent, of a polyfunctional acrylate.
As used in this specification and claims, the term "polyfunctional acrylate" means any of the di-, tri-, -or tetrafunctional acrylate or methacrylate esters defined by the formula:
~. .
- ~ ~ 3 4~ ~
11,350 sheet as quickly as possible upon emergence from the sheet die. In blown film applications, the extrudate usually will not form a self-supporting film bubble at reduced viscosities below about 1.5. It is very di~fi-cult to produce such high viscosity material in con-ve~tional commercial polymerization equipment.
The rheological properties of the lactone polymers have hindered their more widespread acceptance in the field of orthopedic casts, despite the fact that the casts produced from them have excellent properties, i.e. they are lightweight, tough, rigid, water and soil resistant~ and easily removed. The polymer must be hea~ed above its melting polnt in order to apply it as an orthopedic cast material. At the application temper-ature, the polymer tends to be more fl~lid than is desired and, therefore, difficult to handle and apply.
SUMMARY UF THE INVENTION
. . .
The present invention provides a novel copolymer containing a major amount of lactone monomer and a minor amount of a polyfunctional acrylate copolymerized therein.
~; The copolymer is produced under essentially the same reaction conditions which are known to polymerize the lactone alone with the active-hydrogen containing initiator, except that the polyfunctional acrylat~ is additionally present in the polymerization reaction mixture.
The thermoplastic, crosslinkable copolymers of this invention display no significant degree of ~ 11,350 crosslinking themselves - as measured by gel content - yet they are highly susceptible to crosslinking by exposure to actinic or ionizing radiation. It was quite surprising that the copolymers produced in this manner displayed these properties. On the basis o the known mechanism of lactone polymerization and the structure of the polyfunctional acrylate monomers, it would be expected either that the polyfunctional acrylate would not coreact in the polymeriza-tion reaction mixture or that, if it did react, the reaction product itself would be highly crosslinked. Yet, this was not the case. Analysis of the double bond content of the thermoplastic, crosslinkable copolymer of this invention indicated that ? where a difunctional acrylate was employed, approximately half the double bonds initially present in the difunctional acrylate monomer were consumed in the polymerization reaction, indicating reaction of at least a major portion of the difunctional acrylate. Based on solubility and melt index behavior, the thermoplastic, crosslinkable copolymers themselves show little or no evidence of crosslinking.
The thermoplastic, crosslinkable copolymers of this invention can be crosslinked by heat and free radical pe-oxide catalysts, however, we prefer to cross- ~ -link them by exposure to ionizing or actinic radiation, such as electron beam or ultraviolet radiation. The thermoplastic, crosslinkable copoIymers are remarkable in their response to actinic radiation~ In comparing the ~
,, .
2 11,350 thermoplastic copolymers of this invention with physical blends of lactone homopolymer and polyfunctional acrylate, the copolymers exhibited a much more rapid crosslinking response to electron beam irradiation, determined by measuring melt index as a function of radiation dosage.
The degree of crosslinking which is imparted to the thermoplastic, crosslink2ble copolymer is readily controllable according to the desires of the practitioner, for example, by controlling the dosage o radiation. By controlling the degree of crosslinking, one can produce a range of crosslinked copolymers which display varying rheological properties. At one end of the spectrum, one can produce a lightly crosslinked copolymer (e.g. no detectable gel in methylene dichloride at 35C.) which is processable by all the conventional thermoplastic process-ing methods, such as extrusion, yet displays melt properties which are more desirable than the corresponding lactone homopolymers of similar reduced viscosity. It is thus possible to extrude sheets of the lightly crosslinked copolymer wi~hout the use of chill roll equipment and to blow film from the crosslinked copolymer at considerably ` ~ lower reduced viscosities (i.e., molecular weights) than is possible with the corresponding lactone homopolymer. At higher levels of crosslinking, wherein the copolymer con-~ains a gel phaseg it exhibits a soft, rubbery consistency over a fairly broad temperature range. In applications ~., _ 5 ~ 11,350 such as orthopedic casts and splints, such a material is much easier to handle during the application process than the corresponding lactone homopolymer.
The thermoplastic, crosslinkable copolymers display physical and mechanical properties at room temperature which are similar to those of lactone homopolymers having considerably higher molecular weight.
BRIEF DESCRIPTION OF THE DRAWINGS
Figure 1 is a graph which plots melt index at 190C. as a function of radiation dosage of electron beam radiation for: a physical blend containing 98 weight percent of the poly-epsilon-caprolactone h~mopolymer and 2 weight percent neopentyl glycol diacrylate; the same physical blend after 4 hours at 190C., a copolymer of epsilon-caprolactone and neopentyl glycol diacrylate containing 2 weight percent neopentyl glycol diacrylate copolymerized therein; and a copolymer of epsilon-caprolactone and neo-pentyl glycol diacrylate containing 4 weight percent neo-pentyl glycol diacrylate copolymerized therein. ~- `
Figure 2 is a graph which presents a series of ~`
stiffness-temperature curves which plot 1% secant modulus as a function of temperature for three crosslinked copolymers produced by irradiating a copolymer of epsilon-caprolactone and neopentyl glycol diacrylate (2 weight percent) with doses of 2, 5, and 10 megarads of electron beam radiation.
~ ~ 3 ~ ~ 2 11,350 DETAILED DESCRIPTION OF THE INVENTION
The thermoplastic, crosslinkable copolymer of this invention is produced by reacting, at a temperature of from 25 to 300~C., an active-hydrogen containing initiator with a moLIr excess of a monomer mixture comprising:
(A) from 90 to 99.5 weight percent preferably from g5 to 99.5 weight percent of at least one lactone of the formula:
R
R-CH~ C -~ C=O
R
. ~. O
wherein n is an integer having a value of from about 3 to 6, at least n~2 of the R's are hydrogen and the . remaining R's are alkyl of up to 10 carbons; and (B) from 0.5 to 10 weight percent preferably from 0.5 to 5 weight percent, of a polyfunctional acrylate.
As used in this specification and claims, the term "polyfunctional acrylate" means any of the di-, tri-, -or tetrafunctional acrylate or methacrylate esters defined by the formula:
~. .
3 ~ .,350 O - O
., ll CH2aCG - R' -- GC=CH2 D D _ x wherein D is hydrogen or methyl, x has a value o~ 1 to 3, R' is -O-CHz~CCH2Y or ,~
-O(CH2CHO ~ or 10 z OOCyH~yO-wherein each X is hydrogen or -O-, Y is -O-, methyl, or CH3 :
: CH3 . ~:
-,.
is hydrogen or alkyl of 1 to 2 carbon atoms, _ has a value of from 2 to 6, and y has a value from 2 to 15. - `
Illustrative~ of the lactone monomers useful in this invention one can mention epsilon-caprolactone, ;
~ 20 zeta-en~antholactone, delta-valerolactone~ the mono- ~ ;
:; ~ alkyl-delta-valerolactone, e.g., the monomethyl-,~
: ~ monoethyl-, mono-n-hexyl-delta-valerolactones, and the like;:the monoalkyl-, dialkyl-, and trialkyl-epsilon- :
caprolactones~ e.g., the monomethyl-, monoethyl-, mono-n-propyl-, dimethyl-, diethyl-, di-n-propyl, trimethyl-, triethyl-, tri- -propyl-epsilon-caprolactones, and the like.
~: - 8 -, :
~ ~ 3 ~ 11,350 One can mention, as illustrative of the poly-functional acrylates described by the formulas above, neopentyl glycol diacrylate, neopentyl glycol dimeth-acrylate, trimethylolpropane triacrylate, trimethylol-propane trimethacrylate, butanediol diacrylate, butane-diol dimethacrylate, 3'-acryloxy-2',2'-dimethylpropyl 3-acryloxy-2,2-dimPthylpropionate, ethylene gLycol diacrylate, diethylene glycol diacrylate, triethylene glycol triacrylate, pentaerythritol tetraacrylate, and the like.
Those skilled in the art are aware that, in producing the polyfunctional acrylates by esterfying the corresponding polyfunctional alcohols, a small number of residual hydroxyl groups may be present in the product.
A small amount of such groups is tolerable in producing the thermoplastic, crosslinkable copolymer, however, they will act as initiators and their effect on the molecular weight should be taken into consideration.
The identity of the active-hydrogen containing initiators and the reaction conditions which promote the copolymerization of the lactone and polyfunctional acrylate ?
including the nature of useful catalys~s, are essentially the same as those which are known to promote the poly-merization of the lactone monomer alone in the presence of the active-hydrogen containing initiator. The polymerization of lactone monomers with active-hydrogen containing initiators is known in the art and is described in U. S. 3,169,945.
.
~ 11,35U
The active-hydrogen containing initiators which are useful in produc~ng the thermoplastic cross-linkable copolymers are known to those skilled in the art They are compounds having one or more reactive hydrogen atoms which are capable, ~mder the conditions of reaction, of opening the lactone ring and adding it as an open chain without forming water of condensation. Water is a suitable initiator for the reaction. Frequently, the ambient moisture absorbed in the lactons monomer and polyfunctional monomer is sufficient to initiate the reaction. Other suitable initiators include mono~unctional initiators, such as alcohols and amines~ and polyfunctional Lnitiators, such as polyols and polyamines, as well as amides, sulfonamides, hydrozones, semicarbazones, oximes, polycarboxylic acids~ hydrocarboxylic acids, and amino~
carboxylic acids.
As merely illustrative of 6uitable active-hydrogen initiators one can mention: alcohols ~uch 85 methanol, ethanol, propanol, isopropanol, l-butanol, 2-butanol, tert-butanol, l-pentanol, 3-pentanol, tert-~myl alcohol, l-hexanol, 4-methyl-3-pentanol, 1 heptanol, l-octanol, l-nonanol, 3,9-triethyl-6-decanol, lauryl alcohol, benzyl alcohol, phenyl methyl carbinol, cyclo-hexanol, trimethylcyclohexanol; diols such as ethylene glycol, diethylene glycol, triethylene glycol, and the like, 2,2-dimethyl-1,3-propanediol, 2,2-diethyl-1,3-propanediol, 3-methyl-1~5-pentanediol, N-methyl and N-ethyl dlethanolamines, 1~3- or 1,4-cyclohexanediol, ;~
11,350
., ll CH2aCG - R' -- GC=CH2 D D _ x wherein D is hydrogen or methyl, x has a value o~ 1 to 3, R' is -O-CHz~CCH2Y or ,~
-O(CH2CHO ~ or 10 z OOCyH~yO-wherein each X is hydrogen or -O-, Y is -O-, methyl, or CH3 :
: CH3 . ~:
-,.
is hydrogen or alkyl of 1 to 2 carbon atoms, _ has a value of from 2 to 6, and y has a value from 2 to 15. - `
Illustrative~ of the lactone monomers useful in this invention one can mention epsilon-caprolactone, ;
~ 20 zeta-en~antholactone, delta-valerolactone~ the mono- ~ ;
:; ~ alkyl-delta-valerolactone, e.g., the monomethyl-,~
: ~ monoethyl-, mono-n-hexyl-delta-valerolactones, and the like;:the monoalkyl-, dialkyl-, and trialkyl-epsilon- :
caprolactones~ e.g., the monomethyl-, monoethyl-, mono-n-propyl-, dimethyl-, diethyl-, di-n-propyl, trimethyl-, triethyl-, tri- -propyl-epsilon-caprolactones, and the like.
~: - 8 -, :
~ ~ 3 ~ 11,350 One can mention, as illustrative of the poly-functional acrylates described by the formulas above, neopentyl glycol diacrylate, neopentyl glycol dimeth-acrylate, trimethylolpropane triacrylate, trimethylol-propane trimethacrylate, butanediol diacrylate, butane-diol dimethacrylate, 3'-acryloxy-2',2'-dimethylpropyl 3-acryloxy-2,2-dimPthylpropionate, ethylene gLycol diacrylate, diethylene glycol diacrylate, triethylene glycol triacrylate, pentaerythritol tetraacrylate, and the like.
Those skilled in the art are aware that, in producing the polyfunctional acrylates by esterfying the corresponding polyfunctional alcohols, a small number of residual hydroxyl groups may be present in the product.
A small amount of such groups is tolerable in producing the thermoplastic, crosslinkable copolymer, however, they will act as initiators and their effect on the molecular weight should be taken into consideration.
The identity of the active-hydrogen containing initiators and the reaction conditions which promote the copolymerization of the lactone and polyfunctional acrylate ?
including the nature of useful catalys~s, are essentially the same as those which are known to promote the poly-merization of the lactone monomer alone in the presence of the active-hydrogen containing initiator. The polymerization of lactone monomers with active-hydrogen containing initiators is known in the art and is described in U. S. 3,169,945.
.
~ 11,35U
The active-hydrogen containing initiators which are useful in produc~ng the thermoplastic cross-linkable copolymers are known to those skilled in the art They are compounds having one or more reactive hydrogen atoms which are capable, ~mder the conditions of reaction, of opening the lactone ring and adding it as an open chain without forming water of condensation. Water is a suitable initiator for the reaction. Frequently, the ambient moisture absorbed in the lactons monomer and polyfunctional monomer is sufficient to initiate the reaction. Other suitable initiators include mono~unctional initiators, such as alcohols and amines~ and polyfunctional Lnitiators, such as polyols and polyamines, as well as amides, sulfonamides, hydrozones, semicarbazones, oximes, polycarboxylic acids~ hydrocarboxylic acids, and amino~
carboxylic acids.
As merely illustrative of 6uitable active-hydrogen initiators one can mention: alcohols ~uch 85 methanol, ethanol, propanol, isopropanol, l-butanol, 2-butanol, tert-butanol, l-pentanol, 3-pentanol, tert-~myl alcohol, l-hexanol, 4-methyl-3-pentanol, 1 heptanol, l-octanol, l-nonanol, 3,9-triethyl-6-decanol, lauryl alcohol, benzyl alcohol, phenyl methyl carbinol, cyclo-hexanol, trimethylcyclohexanol; diols such as ethylene glycol, diethylene glycol, triethylene glycol, and the like, 2,2-dimethyl-1,3-propanediol, 2,2-diethyl-1,3-propanediol, 3-methyl-1~5-pentanediol, N-methyl and N-ethyl dlethanolamines, 1~3- or 1,4-cyclohexanediol, ;~
11,350
4,4-methylenebiscyclohexanediol, 1,3- or 1,4-xylenediol, 3-or 4-hydroxymethyl-phenethyl alcohol, and 1,4-piperazine-diethanol; amines such as methylamine, ethylamine, n-propyl-amine, isopropylamine, n-butylamine, tertbutylamine, n-amyl-amine, n-hexylamine, 2-ethylhexylamine, aniline, orthotoluene, cyclohexylamine, pyrrolidone, piperadine, and morpholine; and diamines such as methylenediamine, ethylenediamine, n-propylene-diamine, meta- or paraphenylenedi ~line, toluene-2,4-diamine, 1,5-naphthalenediamine, meta- or paraxylylenediamine, 1,4-cyclohexanediamine, and 4,4'-methylenebiscyclohexylæmine.
The above listing of suitable active-hydrogen con-taining initiators whLch can be used in the production of the thermoplastic, crosslinkable copolymer i8 intended to be illus-trat~ve only, and a more complete listing can be found in U.S.
3,169,945, Cols. 2-7.
The polymerization of the lactone and the polyfunc-tional acrylate is preferably carried out in the presence of a lactone polymerization catalyst, such as a basic or neutral ester interchange catalyst, Among catalysts suitable or this purpose are such metals as lithium, sodium, potassium, rubi-dium, cesium, magnesium, calcium, barium, strontium, zinc, aluminum, titanium, cobalt, germanium, tin, lead, antimony, arsenic, and cerium, as well as the alkoxides thereof, Addi-tional suitable catalysts, by way of example, are the carbon-ates of alkali- and alkaline earth metals, zinc borate, lead borate, zinc oxide, lead silicate, lead arsenate, litharge, lead carbonate, antimony trioxide, stannous octoate, and aluminum isopropoxide. The catalysts are employed in the usual ~nown catalytically effective concentrations.
Typically, the catalysts are employed at concentrations ., . . ~ , . ~ .
'~ ~ 3 ~ 11,350 between about 0.001 to 0.5%, preferably from 0.01 to 0.2%, based on the weight of the lactone monomer.
As previously mentioned, the reaction of the lactone monomer, polyfunctional acrylate, and active-hydrogen containing initiator is carried out at a temperature of from 25 to 300~C., and, preferably it is carried out at rom 130 to 225C. The reaction proceeds satisfactorily at atmospheric pressure, ambient reactor pressure, or superatmospheric pressure.
Generally, it is not necessary to carry out the reaction in a solvent, however, a conventional organic solvent can be employed, provided it does not contain active-hydrogen atoms which will act as polymerization initiators.
Reaction time varies widely, depending on the type and amount of initiator, lactone, polyfunctional acrylate and catalyst, reaction temperature, desired molecular weight, ~ reactor design, etc., and can be anywhere from a few minutes ; to 40 hours or more. The product is recovered by con-ventional means.
The thermoplastic, crosslinkable copolymers ; of this invention are solid at room temperature. They have reduced viscosities from about 0.1 to 2.0, measured at a concentration of 2 grams/ml. in ben~ene.
The thermoplastic, crosslinkable copolymer can be crosslinked by exposure to the known forms of actinic or ionizing radiation. Suitable forms of radiation for cross-linking the copolymer include electron beam, alpha~ray, ~ 3~.~ ll,350 `~ beta-ray, x-ray, gam~a-ray, and ultraviolet light. The equipment for generating these forms of radiation is known and requires no further elaboration herein. We prefer to employ electron beam energy for crosslinking ~he copolymer because of its excellent penetrating ability, because it does not require the use of added photolnitiator, and because the equipment for generating thi.s energy is readily commercially available.
If one desires to crosslink the copolymer usin~
non-ionizing radiation, such as ultraviolet, a photo-initiator is blended with the thermoplastic, crosslinkable copolymer prior to crosslinking. Any of the known photo-initiators are suitable. One can mention, as merely illustrative thereof, 2,2-diethoxyacetophenone, benzo-phenone, acetophenone, 2-, or 3-, or 4-bromoacetophenone fluorenone, xanthone, thioxanthone, benzoin, alkyl and aryl ethers of benzoin, m- or p-diacetylbenzene, 2-, or 3-, or 4-methoxybenzophenone, 3- or 4-allylacetophenone, and the like. The photoinitiators are employed at the usual known effective concentrations. Typically, the photoinitiator is employed at a concentration of up to about 10%, preferably from 1 to 5%, based on the weight of the thermoplastic crosslinkable copolymer. Those skilled in the art are aware that photoactivators, or photosynergists, can be used in combination with the photo-initiators and synergistic effects are sometimes obtained.
~ 3~ 3~ 11, 350 The suitable photoactivators are well known and require no further elaboration, however, one can mention as merely illustrative thereof methylamine, ethylamine, diethyl-amine, tributylamine, allylamine, 2-aminoethylethanolamine, tribenzylamine, piperldine, N-cyclohexylethyleneimine, and the like. They are employed in the usual known effective concentrations.
The thermoplastic, crosslinkable copolymer produced in accordance with our invention generally has a broader molecular weight distribution and wider melting range than a corresponding lactone homopol~mer produced by a similar process.
The thermoplastic, crosslinkable copolymers of this invention can be employed in many applications. The degree of crosslinking imparted to the material wilI depend largely on the end use and on the processing or fabricating methods to be employed.
Typically, a thermoplastic, crosslinkable copolymer was produced by copolymerizing epsi~on-caprolac-tone with 2 weight percent neopentyl glycol diacrylateaccording to the process of this invention, resulting in a product having a reduced viscosity of 0.77 and melt index, measured at 190C., of 20~ decigrams/min. The copolymer was discharged ~rom the reactor in strands onto a cold moving belt and, upon soli~ifying, the strands were diced into pellets. Pellets exposed to 0.2 megarads of electron beam .. .. .. ~ :, . :, . ,- . . . .
~ ~ 3~ 11,350 radiation exhibited a drop in melt index to 38 decigrams/min;
pellets exposed to 0.3 rnegarads exhibited a drop in melt index to 1.8 decigrams/min. At these levels of cross-linking the copolymer exhibited no gel in methylene di-chloride and their rheological'characteristics were such that they could be blown into 1.5 mil film on a conventional blown film extrusion line. It is generally preferred to reduce the melt index to from 2 to 0.2 decigrams/min. ~or film blowing applications.
In the field of orthopedic therapeutic devices, custom, contour-~itting casts, splints~ braces, and the like can be produced from the copolymers o~ this invention which have been crosslinked. The casts, splints, etc.
made from this material have all the desirable properties of similar devic'es made from lactone homopolymers, as described in U. S. 3,692,023, however, they are considerably easier to apply due to the better handling characteristics at the application temperature. In'the orthopedic applica-tions it is generally preferred to employ the copolymer at levels of crosslinking such that it exhibits a gel fraction in an organic solvent such as methylene dichloride. The orthopedic therapeutic devices are produced by molding the crosslinked copolymer, typically in form of a sheet, web, or bandage to the body portion being treated. The copolymer used or this purpose can be crosslinked to a gel content of up to 90 weight percent, preferably from 20 to 70 weight percent, basecl on total weight of the copolymer.
~, .
. .
3 ~
11,350 The sheets or webs of crosslînked copolymer employed in the orthopedic applications can consist solely of the crosslinked copol~mer or ~hey can comprise composites or laminates, wherein the copolymer is bonded to or has em~edded therein or is impregnated in a su~strate material in the form of a sheet, web, netting, etc., of a different material.
Typically, a flexible orthopedic cast forming ~andage material was formed by cryogenically grinding pellets of the thermoplastic, crosslinkable copolymer into a powder. The powder was electrostatically spray coated onto a nylon netting which had previously been coated with an electrically conductive coating. The netting having the copolymer coating fused thereon was exposed to 3 megarads of electron beam radiation to crosslink the copolymer. An orthopedic arm~wrist cast was formed from the bandage thus produced by: heating it to a temperature above the sotening point of the crosslinked copolymer; wrapping the ~andage around the arm and wrist, and between the thumb and forefinger, across the palm and thence back to the wrist in a series of overlying layers to build up a sufficient thickness of material to be rigid at room temperature; fusing the overlying layers into a unitary structure by the slight manual application of pressure; and cooling the cast to -room temperature to rigidify it.
Other methods of producing orthopedic cast forming bandages include laminating a substrate, such as cotton gauxe, with one or more layers of a sheet or film of the thermoplastic, crosslinkable copolymer. If . .
16. -., ~, .
11,350 desired the copolymer, i~ pellet form, can be lightly irradiated to reduce its ~eIt index and render it more readily processable lnto a sheet: or film by slot extrusion or blown film extrusion and, subsequent to laminating the sheet or film onto a substrate, it can be further irradiated to achieve the desired degree of stiffness for application as an orthopedic cast.
In producing ortllopedi.c splints, it is convenient to employ the crosslinked copolymer in the form of a sheet of sufficient thickness that a single layer provides the desired degree of support and immobilization to the limb or body part being treated. The sheet is heated above the softening point of the ~opolymer and is thermo-formed to the contour of the body part to which it is applied.
If desired, there can be present in the crosslinked copolymer up to about 20 weight percent, based on the weight of the copolymer, of particulate or fibrous fillers, such as reinforcing fillers, e.g., magnesium or calcium carbonate, finely divided silica, clay, asbestos, etc., or pigments, e.g. titanium dioxide. Dyes or other color agents can aLso be present if desired.
Orthopedic cast and splint forming materials of the crosslinked copolymers are soft and rubbery at the application temperatures, whereas the corresponding lactone homopolymers are considerably more fluid. Thus, the crosslinked copolymer is more easily handled and applied to the patient. If the material is heated in the form of a rolled bandage, the danger of the layers permanently sticking or fusing on the roll can be eliminated by the proper degree of crosslinking.
17.
~ 11,350 The advant~ges in processing which are provided by the copolymers of this invention are ~etter ~nderstood wit~ reference to t~e ~gNres.
Tig. 1 shows ~elt index at 190C. as a function of electron beam radiation dose for copol~mers of epsilon-caprolactone and neopentyl glycol diacrylate at 2% and 4% b~ weight neopentyl glycol diacrylate, as well as for a physical mixture of 98 weight percent poly-epsilon-caprolactone (reduced viscosity 0.8) and 2 weight percent neopentyl glycol diacrylate. For comparison purposes, the melt index of the poly-epsilon caprolactone is about 20 decigrams/min.
In the range from about 0.1 to 0.5 megarads, the copolymers displayed melt indexss in a range which is suitable for processing by means such as injection molding or extrusion. Yet, the melt index is sufficiently reduced at these levels of irradiation that the extrudate ~:
will not cause problems of dimensional instability during , takeoff from the die.
At higher levels of crosslinking (i.e. higher radiation dosage), the character of the material changes.
. .
Fig, 2 shows stiffness v. temperature for a series of copolymers of epsilon-caprolactone and neopentyl glycol :-~
diacrylate (2% by weigh~? which were irradiated with 2, 5, and 10 megarads of electron beam energy. These 18. ~;
~.
~;
11,350 ~ ~ 3 ~
materials are charac~erized by an initial dropoff in stiffness followedby a broad temperature region in which they have a sot, rubbery consistency, represented by the relatively flat portion of the curves. As the level of crosslinking (i.e. radiation dosage) is increased, the soft, rubbery region occurs at a higher level of stiffness~ Thus, sheets of the copolymer can be irradiated to provide optimum properties for thermoforming on commercial vacuum thermoformers. The stifness of the material can be tailored or factors such as the depth of draw in the mold, desired wall thickness, sharpness of angles, etc.
Pellets of the thermoplastic, crosslinkable copolymer can be irradiated to a level of about 0.1 to 0.5 megarads to provide good properties for sheet extrusion and, if desired, the sheet thus formed can be fur~her irradiated to a higher level of crosslinking to provide the desired properties for thermoforming. If desired, the sheet can be differentlally irradiat~d across its surface. For example, suppose that one desires to ~hermofonm a part in which stiffness is a general require- .
ment, but a particular section has a deep draw or sharp angle which requires the matesial to flow freely to conform to the mold. The sheet can be only lightly irradiated in that portlon which is required to flow freely in the mold and the remainder of the sheet irradia~ed to a higher level to provide the needed stiffness.
19.
.: .. - ., . .. ; ~ .. . , ... , , : . ..
11,350 ~ ~ 3 ~
The copolymers of this invention can be molded by other conventional means, such as injection molding, compression molding, etc, Those skilled in the art will know the particular rheological proper-ties required for each of the processes and will be able to adjust the propert~es of the copolymer accordingly.
The examples which follow are intended to further illustrate the invention described above and are not intended to unduly limit the invention in any way.
Unless otherwise stated, all parts and percents ~iven in the examples are by weigh~
The following procedure was employed to determine double bond content (i.e., ,, C=C ~ ).
Double Bond Content. A small sample, on the order of 2 grams, was weighed into an Erlenmeyer flask, equipped wi~h a condenser, into which there were also ~; added 10 ml. of morpholine, 50 ml. of chloroform, and ~
20 ml. of acetic acid~ The temperature of the contents ~ ;
was raised to about 50C. for 30-45 min. to reac~ the morpholine with the double~bonds. The contents were then cooled to room temperature and titrated with 0.5 N perchloric acid in 2-methoxyethyl acetate to a thymol blue-xylene cyanol endpoint A blank con-tain:Lng everything but the sample was also run. The double bond content was then calculated accordi~g to the equation.
: ::
20.
11,350 ~3~
% C=C~ = (A - B)_ x N x O.Ol201 x 100 S. W.
A = ml. of perehloric aeid to titrate sample B = ml. of perchloric acid to titrate blank N = normality of perchloric acid S.W. = sample weight.
As will be seen in the examples which follow, thermoplastic erosslinkable eopolymers of this invention produeed from monomer mixtures eontaining 98 weight per-cent epsilon-caprolactone and 2 weight percent neopentyl glycol diacrylate typieally had double bond eontent of the neopentyl glyeol diacrylate monomer, this would indicate that about 58% o~ the initial double bond unsaturation was present in the thermoplastic erosslinkable copolymer.
Reduced viscosities were determined at 2 g./ml. in benzene.
-- - ~ /
21.
11,350 Example 1 To a l-liter flask equipped with a thermometer, magnetic stirrer, nitrogen purge tube, and Brookfield viscometer there was charged a mixture of 882 grams o epsilon-caprolactone (containing 0.024 wt.% water), 18 grams of neopentyl glycol diacrylate (containing 0.24 wt.% water), and 0.282 ml. of stannous octoate. Due to the water content of the reactants no additional initi-ator was necessary. The reactants were heated with a heating man~le to a temperature of 177C. After two hours the temperature of the reactants had risen to 182C.
and the viscosity was 6,000 cps. After an additional two hours of reaction an exotherm was reached at 221C. The reaction was continued for an additional five hours, at which time the product had a viscosity of 310,000 cps at 140C. The viscous, yellowish product was discharged into a pan lined with silicone-coa~ed ralease paper.
The yield of solid poIymer was 99.61% of the material charged. The polymer had a reduced VlSCoSity of 0.58 in benzene at 30C. and a double bond content of 0.11%.
The solidified polymer was removed from the release paper and granulated in a grinder. Samples of the granulated polymer were irradiated with varying dosages of electron beam energy using a 2 MEV electron accelerator. After irradiation the samples were placed in benzene, tetrahydrofuran, and methylene dichloride and rated for relative degree of crosslinking on a scale 22.
.,. ~ .
11,350 ~.3~
of 0-6, with 6 representing the highesl: degree of crosslinking. At the lower crosslinking levels, degree of crosslinking was judged by viscosity increase whereas at the higher levels (i.e. 5 & 6) insoluble gel was app-arent in the solvents Degree of Crosslinking Radiation dose, C6 ~ CH2C12 THF
megarads ....~
O O O O
0.05 0.10 2 2 2 0.20 3 3 3 0.50 4 4 4 1.0 5 5 5 2.0 6 6 6 THF z tetrahydrofuran Example 2 A thermoplastic crosslinkable copolymer of epsilon-caprolactone and neopentyl glycol diacrylate was prepared by a procedure similar to that of Example 1, except that the reactants contained less water than those of Example 1. The reaction was carried out for about 9 hours, with an exotherm o~ 212C. occurring after 4 hours, 15 min. After 9 hours the ma~erial had a viscosity of 740,000 cps at 130C. The polymer was discharged onto silicone-coated release paper and cooled to room tempera-ture. Yield of solid polymer was 99.3% and the polymer had a double bond content of 0.11%. Due to the lower amount of water used to initiate the reaction, the polymer in this example had a somewhat higher molecular weight than the polymer of Example l~ as indicated by a reduced ll,350 '~ ~ 3 ~
viscosity in benzene of 0.72. Plaques l/8-in. thick were compression molded from a portion of the thermoplastic crosslinkable copolymer and subjected to tensile testing.
As a control, a conventional poly-epsilon-caprolactone homopolymer having a reduced viscosity of 0.95 was simi-larly tested and the results appear in the table below.
Samples of the polymer granules wlere irradiated with varying dosages of electron beam radiation and tested for gel content in methylene dichloride. The gel content was observed to increase with increasing radiation dosage.
Secant modulus, Tensile strength,p.s.i. Elonga~ion,V/.
p~,s.i. _ _ _ at Yield at Break _ _ _at Yield at Break PCL 35,900 1~850 4,000 15 280 Copolyme~ 43,500 2,150 3,300 13 380 PCL = poly-epsilon-caprolactone It can be seen that the thermoplastic copolymer of this invention had mechanical properties comparable to those of poly-epsilon-caprolactone homopolymer of consider-ably higher molecular weight.
Example 3 Using a procedure similar to that of Example 1, a thermoplastic crosslinkable copolymer was produced by copoly- ~;
merizing a monomer mixture containing 98 weight percent epsi-lon-caprolactone and 2 weight percent neopentyl glycol dia crylate, based on to~al monomer weight, using stannous octo-ate as a catalyst and the traces of water in the reactants as the initiator. Similarly~ another thermoplastic crosslinkable copolymer was produced from a monomer mixture containing 96 weight percent epsilon-caprolactone and 4 weight percent neo-pentyl glycol d:iacrylate. There was also produced a physical blend of 98 weight percent of a poly-epsilon~caprolactone homo-polymer having a reduced viscosity of 0.8 and 2 weight percent of neopentyl glycol diacrylate. Each af the copolymers ~nd the physical blend were irradiated with varying do,sages of elec-tronic beam energy from a 2 MEV electron accelerator. Melt index - 24.
. .
, , , .. ,: , . ~
~ ~ 3 ~ 11,350 readings at lP (44 p.s.i.) and 190C. were taken at varying dosage levels and the results are repor~ed in the ~able below.
It can be seen that the copolymer having 2% neopentyl glycol diacrylate copolymerized therein lmderwent a much more rapid crosslinking response than did the physical blend, as indi-cated by the faster drop in melt iLndex upon exposure to radiation.
Melt Inde , decigrams7min Radiation, 98%`PCL/~% NPGDA Copolymer, Copo~ymer, megarads Blend 2% NPGDA 4% NPGDA
0.1 97 8.5 0.2 3.1 0,83 0.3 1.12 0.26 0.5 9.4 0.18 0.06 1,0 3-45 1.5 1.3 0 0 2.0 0.63 0 0 PCL = poly-epsilon-caprolactone NPGDA3 neopentyl glycol diacrylate Example 4 To a 350-gallon jacketed reactor there were charged 1,500 lbs. of epsilon-caprolactone, 30 lbs. of neopentyl glycol diacrylate, 0.6 lbs. of stannous octoate, and 1.5 lbs. of diethylene glycol as initiator. The temperature o the reac-tion mixture was adiabatically raised to 150C. to start the `
reaction. The reaction was carried out for 15 hours, with two exotherms of 207C. and 216C. occurring after 1 hour and 1-1/2 hours. The product was discharged in strands onto a cooled conveyor belt and the sol~idified strands were diced to orm pellets, The product had a reduced viscosity of 0.54, a melt viscosity of 42,000 cps. at 200C~ and a douhle bond content of 0.11%. The polymer pellets were compression molded into 10-mil thick plaques, which were irradiated with 1 megarad of electron beam energy from a 2 MEV electron accelerator. A
25.
.
,. - , ~ , . : , . . .
11,350 portion of one of the irradiated plaques was placed in methylene dichloride and formed a substantial amount of gel. By comparison, a portion of the unirradiated copolymer dissolved completely in methylene dichloride.
A number of 1/8-inch thick compression molded plaqwes were produced and irradiated with 2, 5, and 10 megarad doses of electron beam radiation from a 2 MEV
electron acceleirator. The plaques were tested for mechani-cal properties and the results appear below.
Dose, Modulus, T~nsile strength, p.80i. Elongation, %
me~aradig p.8.i. at Yield at Break _ at Yield at Break 2 43,000 2,920 2,170 15 300 40,000 2,760 2,110 15 20 37,000 2,450 2,000 15 30 A portion of the thermoplastic, crosslinkable copolymer produced in Example 2 and a portion of the thermo-plastic, crosslinkable copolymer produced in this example were each compression molded into a number of plaques of l/8-inch thickness. The plaques were irradiated with 2, 5, and 10 megarads of electron beam energy from a 2 MEV electron accelerator. Finger splints were then formed from the irradiated plaques, as well as from plaques which had not been irradiated. In forming the splints, the plaques were first placed in a hot water bath until the copolymers, which were opaque at room temperature, became translucent, indicating they had passed their crystalline melting points. The softened plaques were then wrapped around a finger in a tube-like manner, the edges were overlapped and fused together, by the slight applicatlon of pressure, and the copolymers were allowed to cool to a rigid state, All of the irradiated -2~, . .
, . ; .,., . ,-, .- .
.
11,350 ~3~
copolymers were easily molded and fusedl yet did not flow excessively or display dimensional instability during application. By comparison, the unirradiated plaques were rather fluid and difficult to handle during application.
The applied splints held the fingers rigidly immobile.
Example 5 Using a procedure similar to that of Example 1, a thermoplastic, crosslinkable copolymer was produced rom a reac~ion mixture of 870.33 grams of epsilon-caprolactone, 18 grams of neopentyl glycol diacrylate, 0.282 mlO of stannous octoate, and 11.67 grams of polyoxypropylene glycol ~viscos-ity at 25C., 300 centistokes) as an initiator. The product was discharged into a pan lined with silic~n-coated release paper. The reduced viscosity of the product was 0.62 and the double bond content, in two repetitive tests, was 0.11 and 0.10%. A piece of the copolymer was dissolved in methy-lene dichloride and formed no gel. Another piece o~ the copolymer was placed under an ultraviolet light overnight and then placed in methylene dichloride, whereupon insoluble gel was observed, indicating that crosslin~ing had occurred.
Example 6 Using a procedure similar to that o~ Example 1, a thermoplastic crosslinkable copolymer was produced by polymerizing a reaction mixture of 877.5 grams of epsilon- `
caprolactone, 18 grams of neopentyl glycol diacrylate~ 0.282 ml. of stannous octoate, and 4.5 grams of butylated hydroxy-toluene (BHT) as an initiator. The product was discharged into a pan lined with a silicone-coated release paper. It had a reduced viscosity of 0~58 and a double bond content, ~ , ~
, 27.
11,350 in two repetitive tests, of 0.10 and 0.11%. A piece of the copolymer was placed in methylene dichloride and found to be soluble. Another piece of the copolymer was placed under an ultraviolet lamp overnight and then placed in methylene di-chloride, whereupon gel was observed, indicating that cross-linking had occurred.
Exam~le 7 Using a procedure similar to that of Example 1, a thermoplastic crosslinkable copolymer was produced by polymerizing a reaction mixture of 881 grams of epsilon~
caprolactone, 19 grams of trimethylolpropane trimethacrylate, and 0.282 ml. of stannous octoate. The water present in the reactants was sufficient to initiate the polymerization without any additional initiator. The viscous reaction product was discharged into a pan lined with a silicone-coated release paper. The copolymer had a reduced viscosity of 0.67 and a double bond content of 0.05%. A piece of the copolymer was observed to be soluble in methylene dichloride.
Another piece of the copolymer was placed under an ultraviolet light overnight and then placed in methylene dichloride, whereupon insosuble gel was observed, indicating that cross-linking had occurred.
Example 8 Using a procedure similar to that of Example 1, thermoplastic crosslinkable copolymers were produced from monomer mixtures containing 90 weight percent epsilon^
caprolactone and 10 weight percent neopentyl glycol diacrylate, based on the to~al weight of those monomers. Two runs were carried out. In both runs, the polymerization mixture charged 28.
.
.
3 ~L3~ 11,350 to the flask consisted of 771.426 grams of epsilon-capro-lactone, 86.256 grams of neopentyl glycol diacrylate, 0.282 ml. of stannous octoate, and 42.309 grams of diethylene glycol as an initiator. ~n the first run the reaction was carried out for about 9 hours, as in Example 1, however, in the second run the reaction was terminated and the product discharged after 1-1/2 hours. The copolymer of the first run had double bond content measurements of 0.38 and 0.36%
in two repetitive tests. The copolymer of the second run had double bond content measurements of 0.6 and 0.62% in two repetitive measurements. Pieces of both copolymers were observed to be soluble in methylene dichloride. Pieces of each copolymer were irradiated with 2, 5, and 10 megarads of electron beam radiation from a 2 MEV electron acceler-ator. In the case of both copolymers, the irradiated samples all exhibited insoluble gel formation in methylene dichloride, with the gel fraction increasing with increased radiation dosage.
Example 9 Using a procedure similar to that of Example 1, a thermoplastic crosslinkable copolymer was produced by polymerizing a reaction mixture of 873.5 grams of epsilon-caprolactone, 26.5 grams of 3'-acryloxy-2', 2'-dimethyl-propyl 3-acryloxy-2,2-dimethylpropionate and 282 ml. stann-ous octoate. The water contained in the reactants was sufficient to initiate reaction without the use of added -initiator. The reaction was carried out for about 11 hours.
The final product had a viscosity of 140,000 cps. at 187C.
and a reduced viscosity of 0.58. The double bond content of the copolymer, in two repetitive measurements, was 0.13 and 0.11%.
29.
~ f~ 11,350 To a 350-gallon jacketed reactor there were charged 2,000 lbs. of epsilon-caprolactone~ 40 lbs. of neopentyl glycol diacrylate, and 365 grams of stannous octoate. Trace water contained in the reaction mixture was the sole initiator employed. The temperature of the reac-tants was raised to 200C. and the reaction was allowed to proceed for 15 hours, Prior to raising the temperature, a small sample of the reactant mixture was taken out oE the reactor and placed in a thermocell. The reaction tempera-ture in the thermocell was regulated to 200C. and the reaction in the thermocell was allowed to proceed for 39 hours. The viscous, yellowish reaction product in the reactor was discharged in strands onto a cooled belt and the solidified strands were diced into pellets. A sample of the copolymer taken near the beginning of the reactor discharge had a reduced viscosity of 0.77 and a double bond content~
in two repetitive measurements, of 0.09 and 0.08%. After 2 months this sample had a reduced viscosity of 0.74 and a crystallization time of 88 seconds. A sample of the copoly-mer taken near the end o the reactor discharge had a reduced viscosity of 0~81 and a double bond content, in two repetitive measurements, of 0.1 and 0.07%. After 2 months this sample had a reduced viscosity of 0.77 and a crystal-lization time of 77 seconds. The reaction product from the thermocell had a reduced viscosity of 0.89, double bond conten~, in two repetitive meas.urements, of 0.09 and 0.08%, and a crystallization time of 49 seconds.
The thermoplastic crosslinkable copolymer produced above had a melt index, at 190C. and lP (44 p~s.i.), of 200 decigrams/min. A first portion of the copolymer pellets was irradiated with 0.2 megarads of electron beam radiation 30.
. .
v~ 11,350 from a 2 MEV electron accelerator. The melt index of this irradiated portion, at lP and 190C. was 38 decigrams/min.
A second portion of copolymer pellets was irradiated with 0.3 megarads of electron beam irradiation from the 2 MEV
electron accelerator~ The melt index, at lP and 190C. of the second irradiated portion was 1.8 decigrams/min.
Each of the irradiated copolymers was extruded through a blown film dieJ The copolymer which had been irradiated with 0.2 megarads produced a film of 105 mils thickness having a width o 9-7/8 inches after the blown film tube was flattened. The copolymer which had been irradiated with 0.3 megarads produced a film of 1.5 mils thickness having a width of 9 inches after the blown film tube was 1attened. The blown ilms were translucent.
Compression molded plaques 1/8 inch thick were prepared from a portion of the thermoplastic, crosslinkable copolymer and exposed to 1, 2, 3, 4, and 5 megarad~ of electron beam energy from a 2 MEV electron accelerator.
Using a Soxlet extractor, it was determined that ~he irradiated plaques contained gel contents, measured in methylene dichloride, of 37.4%, 47.5%, 51.4%, 50~8~/o and 56.1%3 respectively.
Example 11 -~
900 grams of the thermoplastic, crosslinkable copolymer produced in Example 10 and 100 grams of titanium dioxide pigment were charged to a blender and physically blended for 1/2 hour. The mixture was then extrusion blended in a l-inch screw diameter extruder. The material was di-charged through a strand die into an ice bath to solidify 31.
lL,350 the strands. The solidified strands were diced into pellets.
The pellets were cryogenically ground in a laboratory micro-pulverizer at -150 to -200C. to produce a powder.
Several 2-inch wide str.Lps of nylon netting, each
The above listing of suitable active-hydrogen con-taining initiators whLch can be used in the production of the thermoplastic, crosslinkable copolymer i8 intended to be illus-trat~ve only, and a more complete listing can be found in U.S.
3,169,945, Cols. 2-7.
The polymerization of the lactone and the polyfunc-tional acrylate is preferably carried out in the presence of a lactone polymerization catalyst, such as a basic or neutral ester interchange catalyst, Among catalysts suitable or this purpose are such metals as lithium, sodium, potassium, rubi-dium, cesium, magnesium, calcium, barium, strontium, zinc, aluminum, titanium, cobalt, germanium, tin, lead, antimony, arsenic, and cerium, as well as the alkoxides thereof, Addi-tional suitable catalysts, by way of example, are the carbon-ates of alkali- and alkaline earth metals, zinc borate, lead borate, zinc oxide, lead silicate, lead arsenate, litharge, lead carbonate, antimony trioxide, stannous octoate, and aluminum isopropoxide. The catalysts are employed in the usual ~nown catalytically effective concentrations.
Typically, the catalysts are employed at concentrations ., . . ~ , . ~ .
'~ ~ 3 ~ 11,350 between about 0.001 to 0.5%, preferably from 0.01 to 0.2%, based on the weight of the lactone monomer.
As previously mentioned, the reaction of the lactone monomer, polyfunctional acrylate, and active-hydrogen containing initiator is carried out at a temperature of from 25 to 300~C., and, preferably it is carried out at rom 130 to 225C. The reaction proceeds satisfactorily at atmospheric pressure, ambient reactor pressure, or superatmospheric pressure.
Generally, it is not necessary to carry out the reaction in a solvent, however, a conventional organic solvent can be employed, provided it does not contain active-hydrogen atoms which will act as polymerization initiators.
Reaction time varies widely, depending on the type and amount of initiator, lactone, polyfunctional acrylate and catalyst, reaction temperature, desired molecular weight, ~ reactor design, etc., and can be anywhere from a few minutes ; to 40 hours or more. The product is recovered by con-ventional means.
The thermoplastic, crosslinkable copolymers ; of this invention are solid at room temperature. They have reduced viscosities from about 0.1 to 2.0, measured at a concentration of 2 grams/ml. in ben~ene.
The thermoplastic, crosslinkable copolymer can be crosslinked by exposure to the known forms of actinic or ionizing radiation. Suitable forms of radiation for cross-linking the copolymer include electron beam, alpha~ray, ~ 3~.~ ll,350 `~ beta-ray, x-ray, gam~a-ray, and ultraviolet light. The equipment for generating these forms of radiation is known and requires no further elaboration herein. We prefer to employ electron beam energy for crosslinking ~he copolymer because of its excellent penetrating ability, because it does not require the use of added photolnitiator, and because the equipment for generating thi.s energy is readily commercially available.
If one desires to crosslink the copolymer usin~
non-ionizing radiation, such as ultraviolet, a photo-initiator is blended with the thermoplastic, crosslinkable copolymer prior to crosslinking. Any of the known photo-initiators are suitable. One can mention, as merely illustrative thereof, 2,2-diethoxyacetophenone, benzo-phenone, acetophenone, 2-, or 3-, or 4-bromoacetophenone fluorenone, xanthone, thioxanthone, benzoin, alkyl and aryl ethers of benzoin, m- or p-diacetylbenzene, 2-, or 3-, or 4-methoxybenzophenone, 3- or 4-allylacetophenone, and the like. The photoinitiators are employed at the usual known effective concentrations. Typically, the photoinitiator is employed at a concentration of up to about 10%, preferably from 1 to 5%, based on the weight of the thermoplastic crosslinkable copolymer. Those skilled in the art are aware that photoactivators, or photosynergists, can be used in combination with the photo-initiators and synergistic effects are sometimes obtained.
~ 3~ 3~ 11, 350 The suitable photoactivators are well known and require no further elaboration, however, one can mention as merely illustrative thereof methylamine, ethylamine, diethyl-amine, tributylamine, allylamine, 2-aminoethylethanolamine, tribenzylamine, piperldine, N-cyclohexylethyleneimine, and the like. They are employed in the usual known effective concentrations.
The thermoplastic, crosslinkable copolymer produced in accordance with our invention generally has a broader molecular weight distribution and wider melting range than a corresponding lactone homopol~mer produced by a similar process.
The thermoplastic, crosslinkable copolymers of this invention can be employed in many applications. The degree of crosslinking imparted to the material wilI depend largely on the end use and on the processing or fabricating methods to be employed.
Typically, a thermoplastic, crosslinkable copolymer was produced by copolymerizing epsi~on-caprolac-tone with 2 weight percent neopentyl glycol diacrylateaccording to the process of this invention, resulting in a product having a reduced viscosity of 0.77 and melt index, measured at 190C., of 20~ decigrams/min. The copolymer was discharged ~rom the reactor in strands onto a cold moving belt and, upon soli~ifying, the strands were diced into pellets. Pellets exposed to 0.2 megarads of electron beam .. .. .. ~ :, . :, . ,- . . . .
~ ~ 3~ 11,350 radiation exhibited a drop in melt index to 38 decigrams/min;
pellets exposed to 0.3 rnegarads exhibited a drop in melt index to 1.8 decigrams/min. At these levels of cross-linking the copolymer exhibited no gel in methylene di-chloride and their rheological'characteristics were such that they could be blown into 1.5 mil film on a conventional blown film extrusion line. It is generally preferred to reduce the melt index to from 2 to 0.2 decigrams/min. ~or film blowing applications.
In the field of orthopedic therapeutic devices, custom, contour-~itting casts, splints~ braces, and the like can be produced from the copolymers o~ this invention which have been crosslinked. The casts, splints, etc.
made from this material have all the desirable properties of similar devic'es made from lactone homopolymers, as described in U. S. 3,692,023, however, they are considerably easier to apply due to the better handling characteristics at the application temperature. In'the orthopedic applica-tions it is generally preferred to employ the copolymer at levels of crosslinking such that it exhibits a gel fraction in an organic solvent such as methylene dichloride. The orthopedic therapeutic devices are produced by molding the crosslinked copolymer, typically in form of a sheet, web, or bandage to the body portion being treated. The copolymer used or this purpose can be crosslinked to a gel content of up to 90 weight percent, preferably from 20 to 70 weight percent, basecl on total weight of the copolymer.
~, .
. .
3 ~
11,350 The sheets or webs of crosslînked copolymer employed in the orthopedic applications can consist solely of the crosslinked copol~mer or ~hey can comprise composites or laminates, wherein the copolymer is bonded to or has em~edded therein or is impregnated in a su~strate material in the form of a sheet, web, netting, etc., of a different material.
Typically, a flexible orthopedic cast forming ~andage material was formed by cryogenically grinding pellets of the thermoplastic, crosslinkable copolymer into a powder. The powder was electrostatically spray coated onto a nylon netting which had previously been coated with an electrically conductive coating. The netting having the copolymer coating fused thereon was exposed to 3 megarads of electron beam radiation to crosslink the copolymer. An orthopedic arm~wrist cast was formed from the bandage thus produced by: heating it to a temperature above the sotening point of the crosslinked copolymer; wrapping the ~andage around the arm and wrist, and between the thumb and forefinger, across the palm and thence back to the wrist in a series of overlying layers to build up a sufficient thickness of material to be rigid at room temperature; fusing the overlying layers into a unitary structure by the slight manual application of pressure; and cooling the cast to -room temperature to rigidify it.
Other methods of producing orthopedic cast forming bandages include laminating a substrate, such as cotton gauxe, with one or more layers of a sheet or film of the thermoplastic, crosslinkable copolymer. If . .
16. -., ~, .
11,350 desired the copolymer, i~ pellet form, can be lightly irradiated to reduce its ~eIt index and render it more readily processable lnto a sheet: or film by slot extrusion or blown film extrusion and, subsequent to laminating the sheet or film onto a substrate, it can be further irradiated to achieve the desired degree of stiffness for application as an orthopedic cast.
In producing ortllopedi.c splints, it is convenient to employ the crosslinked copolymer in the form of a sheet of sufficient thickness that a single layer provides the desired degree of support and immobilization to the limb or body part being treated. The sheet is heated above the softening point of the ~opolymer and is thermo-formed to the contour of the body part to which it is applied.
If desired, there can be present in the crosslinked copolymer up to about 20 weight percent, based on the weight of the copolymer, of particulate or fibrous fillers, such as reinforcing fillers, e.g., magnesium or calcium carbonate, finely divided silica, clay, asbestos, etc., or pigments, e.g. titanium dioxide. Dyes or other color agents can aLso be present if desired.
Orthopedic cast and splint forming materials of the crosslinked copolymers are soft and rubbery at the application temperatures, whereas the corresponding lactone homopolymers are considerably more fluid. Thus, the crosslinked copolymer is more easily handled and applied to the patient. If the material is heated in the form of a rolled bandage, the danger of the layers permanently sticking or fusing on the roll can be eliminated by the proper degree of crosslinking.
17.
~ 11,350 The advant~ges in processing which are provided by the copolymers of this invention are ~etter ~nderstood wit~ reference to t~e ~gNres.
Tig. 1 shows ~elt index at 190C. as a function of electron beam radiation dose for copol~mers of epsilon-caprolactone and neopentyl glycol diacrylate at 2% and 4% b~ weight neopentyl glycol diacrylate, as well as for a physical mixture of 98 weight percent poly-epsilon-caprolactone (reduced viscosity 0.8) and 2 weight percent neopentyl glycol diacrylate. For comparison purposes, the melt index of the poly-epsilon caprolactone is about 20 decigrams/min.
In the range from about 0.1 to 0.5 megarads, the copolymers displayed melt indexss in a range which is suitable for processing by means such as injection molding or extrusion. Yet, the melt index is sufficiently reduced at these levels of irradiation that the extrudate ~:
will not cause problems of dimensional instability during , takeoff from the die.
At higher levels of crosslinking (i.e. higher radiation dosage), the character of the material changes.
. .
Fig, 2 shows stiffness v. temperature for a series of copolymers of epsilon-caprolactone and neopentyl glycol :-~
diacrylate (2% by weigh~? which were irradiated with 2, 5, and 10 megarads of electron beam energy. These 18. ~;
~.
~;
11,350 ~ ~ 3 ~
materials are charac~erized by an initial dropoff in stiffness followedby a broad temperature region in which they have a sot, rubbery consistency, represented by the relatively flat portion of the curves. As the level of crosslinking (i.e. radiation dosage) is increased, the soft, rubbery region occurs at a higher level of stiffness~ Thus, sheets of the copolymer can be irradiated to provide optimum properties for thermoforming on commercial vacuum thermoformers. The stifness of the material can be tailored or factors such as the depth of draw in the mold, desired wall thickness, sharpness of angles, etc.
Pellets of the thermoplastic, crosslinkable copolymer can be irradiated to a level of about 0.1 to 0.5 megarads to provide good properties for sheet extrusion and, if desired, the sheet thus formed can be fur~her irradiated to a higher level of crosslinking to provide the desired properties for thermoforming. If desired, the sheet can be differentlally irradiat~d across its surface. For example, suppose that one desires to ~hermofonm a part in which stiffness is a general require- .
ment, but a particular section has a deep draw or sharp angle which requires the matesial to flow freely to conform to the mold. The sheet can be only lightly irradiated in that portlon which is required to flow freely in the mold and the remainder of the sheet irradia~ed to a higher level to provide the needed stiffness.
19.
.: .. - ., . .. ; ~ .. . , ... , , : . ..
11,350 ~ ~ 3 ~
The copolymers of this invention can be molded by other conventional means, such as injection molding, compression molding, etc, Those skilled in the art will know the particular rheological proper-ties required for each of the processes and will be able to adjust the propert~es of the copolymer accordingly.
The examples which follow are intended to further illustrate the invention described above and are not intended to unduly limit the invention in any way.
Unless otherwise stated, all parts and percents ~iven in the examples are by weigh~
The following procedure was employed to determine double bond content (i.e., ,, C=C ~ ).
Double Bond Content. A small sample, on the order of 2 grams, was weighed into an Erlenmeyer flask, equipped wi~h a condenser, into which there were also ~; added 10 ml. of morpholine, 50 ml. of chloroform, and ~
20 ml. of acetic acid~ The temperature of the contents ~ ;
was raised to about 50C. for 30-45 min. to reac~ the morpholine with the double~bonds. The contents were then cooled to room temperature and titrated with 0.5 N perchloric acid in 2-methoxyethyl acetate to a thymol blue-xylene cyanol endpoint A blank con-tain:Lng everything but the sample was also run. The double bond content was then calculated accordi~g to the equation.
: ::
20.
11,350 ~3~
% C=C~ = (A - B)_ x N x O.Ol201 x 100 S. W.
A = ml. of perehloric aeid to titrate sample B = ml. of perchloric acid to titrate blank N = normality of perchloric acid S.W. = sample weight.
As will be seen in the examples which follow, thermoplastic erosslinkable eopolymers of this invention produeed from monomer mixtures eontaining 98 weight per-cent epsilon-caprolactone and 2 weight percent neopentyl glycol diacrylate typieally had double bond eontent of the neopentyl glyeol diacrylate monomer, this would indicate that about 58% o~ the initial double bond unsaturation was present in the thermoplastic erosslinkable copolymer.
Reduced viscosities were determined at 2 g./ml. in benzene.
-- - ~ /
21.
11,350 Example 1 To a l-liter flask equipped with a thermometer, magnetic stirrer, nitrogen purge tube, and Brookfield viscometer there was charged a mixture of 882 grams o epsilon-caprolactone (containing 0.024 wt.% water), 18 grams of neopentyl glycol diacrylate (containing 0.24 wt.% water), and 0.282 ml. of stannous octoate. Due to the water content of the reactants no additional initi-ator was necessary. The reactants were heated with a heating man~le to a temperature of 177C. After two hours the temperature of the reactants had risen to 182C.
and the viscosity was 6,000 cps. After an additional two hours of reaction an exotherm was reached at 221C. The reaction was continued for an additional five hours, at which time the product had a viscosity of 310,000 cps at 140C. The viscous, yellowish product was discharged into a pan lined with silicone-coa~ed ralease paper.
The yield of solid poIymer was 99.61% of the material charged. The polymer had a reduced VlSCoSity of 0.58 in benzene at 30C. and a double bond content of 0.11%.
The solidified polymer was removed from the release paper and granulated in a grinder. Samples of the granulated polymer were irradiated with varying dosages of electron beam energy using a 2 MEV electron accelerator. After irradiation the samples were placed in benzene, tetrahydrofuran, and methylene dichloride and rated for relative degree of crosslinking on a scale 22.
.,. ~ .
11,350 ~.3~
of 0-6, with 6 representing the highesl: degree of crosslinking. At the lower crosslinking levels, degree of crosslinking was judged by viscosity increase whereas at the higher levels (i.e. 5 & 6) insoluble gel was app-arent in the solvents Degree of Crosslinking Radiation dose, C6 ~ CH2C12 THF
megarads ....~
O O O O
0.05 0.10 2 2 2 0.20 3 3 3 0.50 4 4 4 1.0 5 5 5 2.0 6 6 6 THF z tetrahydrofuran Example 2 A thermoplastic crosslinkable copolymer of epsilon-caprolactone and neopentyl glycol diacrylate was prepared by a procedure similar to that of Example 1, except that the reactants contained less water than those of Example 1. The reaction was carried out for about 9 hours, with an exotherm o~ 212C. occurring after 4 hours, 15 min. After 9 hours the ma~erial had a viscosity of 740,000 cps at 130C. The polymer was discharged onto silicone-coated release paper and cooled to room tempera-ture. Yield of solid polymer was 99.3% and the polymer had a double bond content of 0.11%. Due to the lower amount of water used to initiate the reaction, the polymer in this example had a somewhat higher molecular weight than the polymer of Example l~ as indicated by a reduced ll,350 '~ ~ 3 ~
viscosity in benzene of 0.72. Plaques l/8-in. thick were compression molded from a portion of the thermoplastic crosslinkable copolymer and subjected to tensile testing.
As a control, a conventional poly-epsilon-caprolactone homopolymer having a reduced viscosity of 0.95 was simi-larly tested and the results appear in the table below.
Samples of the polymer granules wlere irradiated with varying dosages of electron beam radiation and tested for gel content in methylene dichloride. The gel content was observed to increase with increasing radiation dosage.
Secant modulus, Tensile strength,p.s.i. Elonga~ion,V/.
p~,s.i. _ _ _ at Yield at Break _ _ _at Yield at Break PCL 35,900 1~850 4,000 15 280 Copolyme~ 43,500 2,150 3,300 13 380 PCL = poly-epsilon-caprolactone It can be seen that the thermoplastic copolymer of this invention had mechanical properties comparable to those of poly-epsilon-caprolactone homopolymer of consider-ably higher molecular weight.
Example 3 Using a procedure similar to that of Example 1, a thermoplastic crosslinkable copolymer was produced by copoly- ~;
merizing a monomer mixture containing 98 weight percent epsi-lon-caprolactone and 2 weight percent neopentyl glycol dia crylate, based on to~al monomer weight, using stannous octo-ate as a catalyst and the traces of water in the reactants as the initiator. Similarly~ another thermoplastic crosslinkable copolymer was produced from a monomer mixture containing 96 weight percent epsilon-caprolactone and 4 weight percent neo-pentyl glycol d:iacrylate. There was also produced a physical blend of 98 weight percent of a poly-epsilon~caprolactone homo-polymer having a reduced viscosity of 0.8 and 2 weight percent of neopentyl glycol diacrylate. Each af the copolymers ~nd the physical blend were irradiated with varying do,sages of elec-tronic beam energy from a 2 MEV electron accelerator. Melt index - 24.
. .
, , , .. ,: , . ~
~ ~ 3 ~ 11,350 readings at lP (44 p.s.i.) and 190C. were taken at varying dosage levels and the results are repor~ed in the ~able below.
It can be seen that the copolymer having 2% neopentyl glycol diacrylate copolymerized therein lmderwent a much more rapid crosslinking response than did the physical blend, as indi-cated by the faster drop in melt iLndex upon exposure to radiation.
Melt Inde , decigrams7min Radiation, 98%`PCL/~% NPGDA Copolymer, Copo~ymer, megarads Blend 2% NPGDA 4% NPGDA
0.1 97 8.5 0.2 3.1 0,83 0.3 1.12 0.26 0.5 9.4 0.18 0.06 1,0 3-45 1.5 1.3 0 0 2.0 0.63 0 0 PCL = poly-epsilon-caprolactone NPGDA3 neopentyl glycol diacrylate Example 4 To a 350-gallon jacketed reactor there were charged 1,500 lbs. of epsilon-caprolactone, 30 lbs. of neopentyl glycol diacrylate, 0.6 lbs. of stannous octoate, and 1.5 lbs. of diethylene glycol as initiator. The temperature o the reac-tion mixture was adiabatically raised to 150C. to start the `
reaction. The reaction was carried out for 15 hours, with two exotherms of 207C. and 216C. occurring after 1 hour and 1-1/2 hours. The product was discharged in strands onto a cooled conveyor belt and the sol~idified strands were diced to orm pellets, The product had a reduced viscosity of 0.54, a melt viscosity of 42,000 cps. at 200C~ and a douhle bond content of 0.11%. The polymer pellets were compression molded into 10-mil thick plaques, which were irradiated with 1 megarad of electron beam energy from a 2 MEV electron accelerator. A
25.
.
,. - , ~ , . : , . . .
11,350 portion of one of the irradiated plaques was placed in methylene dichloride and formed a substantial amount of gel. By comparison, a portion of the unirradiated copolymer dissolved completely in methylene dichloride.
A number of 1/8-inch thick compression molded plaqwes were produced and irradiated with 2, 5, and 10 megarad doses of electron beam radiation from a 2 MEV
electron acceleirator. The plaques were tested for mechani-cal properties and the results appear below.
Dose, Modulus, T~nsile strength, p.80i. Elongation, %
me~aradig p.8.i. at Yield at Break _ at Yield at Break 2 43,000 2,920 2,170 15 300 40,000 2,760 2,110 15 20 37,000 2,450 2,000 15 30 A portion of the thermoplastic, crosslinkable copolymer produced in Example 2 and a portion of the thermo-plastic, crosslinkable copolymer produced in this example were each compression molded into a number of plaques of l/8-inch thickness. The plaques were irradiated with 2, 5, and 10 megarads of electron beam energy from a 2 MEV electron accelerator. Finger splints were then formed from the irradiated plaques, as well as from plaques which had not been irradiated. In forming the splints, the plaques were first placed in a hot water bath until the copolymers, which were opaque at room temperature, became translucent, indicating they had passed their crystalline melting points. The softened plaques were then wrapped around a finger in a tube-like manner, the edges were overlapped and fused together, by the slight applicatlon of pressure, and the copolymers were allowed to cool to a rigid state, All of the irradiated -2~, . .
, . ; .,., . ,-, .- .
.
11,350 ~3~
copolymers were easily molded and fusedl yet did not flow excessively or display dimensional instability during application. By comparison, the unirradiated plaques were rather fluid and difficult to handle during application.
The applied splints held the fingers rigidly immobile.
Example 5 Using a procedure similar to that of Example 1, a thermoplastic, crosslinkable copolymer was produced rom a reac~ion mixture of 870.33 grams of epsilon-caprolactone, 18 grams of neopentyl glycol diacrylate, 0.282 mlO of stannous octoate, and 11.67 grams of polyoxypropylene glycol ~viscos-ity at 25C., 300 centistokes) as an initiator. The product was discharged into a pan lined with silic~n-coated release paper. The reduced viscosity of the product was 0.62 and the double bond content, in two repetitive tests, was 0.11 and 0.10%. A piece of the copolymer was dissolved in methy-lene dichloride and formed no gel. Another piece o~ the copolymer was placed under an ultraviolet light overnight and then placed in methylene dichloride, whereupon insoluble gel was observed, indicating that crosslin~ing had occurred.
Example 6 Using a procedure similar to that o~ Example 1, a thermoplastic crosslinkable copolymer was produced by polymerizing a reaction mixture of 877.5 grams of epsilon- `
caprolactone, 18 grams of neopentyl glycol diacrylate~ 0.282 ml. of stannous octoate, and 4.5 grams of butylated hydroxy-toluene (BHT) as an initiator. The product was discharged into a pan lined with a silicone-coated release paper. It had a reduced viscosity of 0~58 and a double bond content, ~ , ~
, 27.
11,350 in two repetitive tests, of 0.10 and 0.11%. A piece of the copolymer was placed in methylene dichloride and found to be soluble. Another piece of the copolymer was placed under an ultraviolet lamp overnight and then placed in methylene di-chloride, whereupon gel was observed, indicating that cross-linking had occurred.
Exam~le 7 Using a procedure similar to that of Example 1, a thermoplastic crosslinkable copolymer was produced by polymerizing a reaction mixture of 881 grams of epsilon~
caprolactone, 19 grams of trimethylolpropane trimethacrylate, and 0.282 ml. of stannous octoate. The water present in the reactants was sufficient to initiate the polymerization without any additional initiator. The viscous reaction product was discharged into a pan lined with a silicone-coated release paper. The copolymer had a reduced viscosity of 0.67 and a double bond content of 0.05%. A piece of the copolymer was observed to be soluble in methylene dichloride.
Another piece of the copolymer was placed under an ultraviolet light overnight and then placed in methylene dichloride, whereupon insosuble gel was observed, indicating that cross-linking had occurred.
Example 8 Using a procedure similar to that of Example 1, thermoplastic crosslinkable copolymers were produced from monomer mixtures containing 90 weight percent epsilon^
caprolactone and 10 weight percent neopentyl glycol diacrylate, based on the to~al weight of those monomers. Two runs were carried out. In both runs, the polymerization mixture charged 28.
.
.
3 ~L3~ 11,350 to the flask consisted of 771.426 grams of epsilon-capro-lactone, 86.256 grams of neopentyl glycol diacrylate, 0.282 ml. of stannous octoate, and 42.309 grams of diethylene glycol as an initiator. ~n the first run the reaction was carried out for about 9 hours, as in Example 1, however, in the second run the reaction was terminated and the product discharged after 1-1/2 hours. The copolymer of the first run had double bond content measurements of 0.38 and 0.36%
in two repetitive tests. The copolymer of the second run had double bond content measurements of 0.6 and 0.62% in two repetitive measurements. Pieces of both copolymers were observed to be soluble in methylene dichloride. Pieces of each copolymer were irradiated with 2, 5, and 10 megarads of electron beam radiation from a 2 MEV electron acceler-ator. In the case of both copolymers, the irradiated samples all exhibited insoluble gel formation in methylene dichloride, with the gel fraction increasing with increased radiation dosage.
Example 9 Using a procedure similar to that of Example 1, a thermoplastic crosslinkable copolymer was produced by polymerizing a reaction mixture of 873.5 grams of epsilon-caprolactone, 26.5 grams of 3'-acryloxy-2', 2'-dimethyl-propyl 3-acryloxy-2,2-dimethylpropionate and 282 ml. stann-ous octoate. The water contained in the reactants was sufficient to initiate reaction without the use of added -initiator. The reaction was carried out for about 11 hours.
The final product had a viscosity of 140,000 cps. at 187C.
and a reduced viscosity of 0.58. The double bond content of the copolymer, in two repetitive measurements, was 0.13 and 0.11%.
29.
~ f~ 11,350 To a 350-gallon jacketed reactor there were charged 2,000 lbs. of epsilon-caprolactone~ 40 lbs. of neopentyl glycol diacrylate, and 365 grams of stannous octoate. Trace water contained in the reaction mixture was the sole initiator employed. The temperature of the reac-tants was raised to 200C. and the reaction was allowed to proceed for 15 hours, Prior to raising the temperature, a small sample of the reactant mixture was taken out oE the reactor and placed in a thermocell. The reaction tempera-ture in the thermocell was regulated to 200C. and the reaction in the thermocell was allowed to proceed for 39 hours. The viscous, yellowish reaction product in the reactor was discharged in strands onto a cooled belt and the solidified strands were diced into pellets. A sample of the copolymer taken near the beginning of the reactor discharge had a reduced viscosity of 0.77 and a double bond content~
in two repetitive measurements, of 0.09 and 0.08%. After 2 months this sample had a reduced viscosity of 0.74 and a crystallization time of 88 seconds. A sample of the copoly-mer taken near the end o the reactor discharge had a reduced viscosity of 0~81 and a double bond content, in two repetitive measurements, of 0.1 and 0.07%. After 2 months this sample had a reduced viscosity of 0.77 and a crystal-lization time of 77 seconds. The reaction product from the thermocell had a reduced viscosity of 0.89, double bond conten~, in two repetitive meas.urements, of 0.09 and 0.08%, and a crystallization time of 49 seconds.
The thermoplastic crosslinkable copolymer produced above had a melt index, at 190C. and lP (44 p~s.i.), of 200 decigrams/min. A first portion of the copolymer pellets was irradiated with 0.2 megarads of electron beam radiation 30.
. .
v~ 11,350 from a 2 MEV electron accelerator. The melt index of this irradiated portion, at lP and 190C. was 38 decigrams/min.
A second portion of copolymer pellets was irradiated with 0.3 megarads of electron beam irradiation from the 2 MEV
electron accelerator~ The melt index, at lP and 190C. of the second irradiated portion was 1.8 decigrams/min.
Each of the irradiated copolymers was extruded through a blown film dieJ The copolymer which had been irradiated with 0.2 megarads produced a film of 105 mils thickness having a width o 9-7/8 inches after the blown film tube was flattened. The copolymer which had been irradiated with 0.3 megarads produced a film of 1.5 mils thickness having a width of 9 inches after the blown film tube was 1attened. The blown ilms were translucent.
Compression molded plaques 1/8 inch thick were prepared from a portion of the thermoplastic, crosslinkable copolymer and exposed to 1, 2, 3, 4, and 5 megarad~ of electron beam energy from a 2 MEV electron accelerator.
Using a Soxlet extractor, it was determined that ~he irradiated plaques contained gel contents, measured in methylene dichloride, of 37.4%, 47.5%, 51.4%, 50~8~/o and 56.1%3 respectively.
Example 11 -~
900 grams of the thermoplastic, crosslinkable copolymer produced in Example 10 and 100 grams of titanium dioxide pigment were charged to a blender and physically blended for 1/2 hour. The mixture was then extrusion blended in a l-inch screw diameter extruder. The material was di-charged through a strand die into an ice bath to solidify 31.
lL,350 the strands. The solidified strands were diced into pellets.
The pellets were cryogenically ground in a laboratory micro-pulverizer at -150 to -200C. to produce a powder.
Several 2-inch wide str.Lps of nylon netting, each
5 ft. in length (86 strands per t.), were dipped in a solvent solution of an electrical:Ly conductive coating (supplied under the tradename Ransprep~, Ransburg Electro-Coating Corp.) and the soLvent was evaporated. The netting having the electrically conductive coating on its surface was electrostatically spray coated with the thermoplastic, crosslinkable copolymer powder. Applied coating weight was about 80 weight percent of ~he total weight of the coated netting. When the applied powder coating had been fused, the openings between the strands of the coated substrate were still present; that is, the coating did not bridge or close the openings.
The netting having the thermoplastic crosslinkable copolymer coating on its surfaces was irradiated with 3 megarads of electron beam energy from a 2 MEV electron accelerator to crosslink the copolymer.
The strips of netting having the crosslinked copoly-mer on their surfaces were rolled, placed into a 650-watt microwave oven, and heated to about 75C., at which tempera-ture the copolymer became soft and moldable, but not highly fluid. A cloth stockinette was placed over the forearm of a subject. The heated, coated strips of netting were then used as an orthopedic cast forming bandage to apply a forearm-wrist cast to the subject. The heated bandage was drawn off the roll, with no sticking problems, and wrapped around the forearm and wrist, passing over the back of the hand, between the thumb and forefinger, across the palm, thence back to the wrist. A series of layers was applied in this manner, taking ~-- 32.
., .. , , . . ~ . -, ~ ~ 3 ~ 1,350 tucks wherever necessary, to build up a sufficient thickness of material to provide support and immobilization of the limb at room temperature. With a slight application of pressure to ensure good surface contact between the overlying layers, the copolymer on the layers fused together so that a unitary cast was formed. When the cast had cooled to room tempera-ture, it was rigid, porous, and contour fitting and held the arm and wrist rigidly in place.
Example 12 To a 350-gallon jacketed reactor there were charged 4,000 lb. of epsilon-caprolactone, 80 lb~ of neopentyl glycol diacrylate, and 7~6 grams of stannous octoate. Trace amounts of water in the reactants were sufficient to act as a poly-merization initiator. The temperature of the reactants was raised to 150C. to start the reaction~ The reaction pro-ceeded for about 16 hours, with an exotherm of 224C. occurrlng after about 5 hours. The viscous product was discharged in strands onto a cooled conveyor belt and the solidiied strands were diced into pellets. The product had a reduced viscosity of 0.5.
Strips of unsized knitted nylon netting, each 4 inches in width and 5 ft. in length (86 s~rands per ft.), were mounted in a fume hood. A 10 weight percent solution ;
of the copolymer produced above, in methylene dichloride, was prepared. There was then added to the solution 10 weight percent titanium dioxide, based on the weight of the copolymer. The solution thus prepared was sprayed on both sides of the nylon netting. After drying overnight, the applied coating weight was about 80 weight percen~ of the ' .
~ 11,350 total weight of the coated netting. The copolymer on the netting was crosslinked by exposure to 3 megarads of electron beam energy from a 2 MEV electron accelerator. The gel content of the crosslinked copolymer on the netting was de~ermined to be 54 weight percent, using a Soxlet extractor.
The strips of netting having the coating of cross-linked copolymer on their strands were employed as an orthopedic cast forming bandage. The strips of bandage were rolled, placed in a 650-watt microwave oven, and heated to a temperature at which the copolymer became sot and moldable. A cloth stockinette was placed over the lower leg and foot. The heated bandage was drawn off the roll and wrapped around the lower leg, ankle, and foot in a series of overlying layers to build up a sufficient thickness of material to provide support and immobilize the limb at room temperature, The overlying layers were fused together by the slight application of pressure to ensure good surface contact. The cast was allowed ~o cool. It formed a rigid, porous cast which held the lower leg and foot in a rigid position. The applied cast had sufficient load-bearing strength to allow the subject to walk on it without bending or breaking it.
'' ' 34~
The netting having the thermoplastic crosslinkable copolymer coating on its surfaces was irradiated with 3 megarads of electron beam energy from a 2 MEV electron accelerator to crosslink the copolymer.
The strips of netting having the crosslinked copoly-mer on their surfaces were rolled, placed into a 650-watt microwave oven, and heated to about 75C., at which tempera-ture the copolymer became soft and moldable, but not highly fluid. A cloth stockinette was placed over the forearm of a subject. The heated, coated strips of netting were then used as an orthopedic cast forming bandage to apply a forearm-wrist cast to the subject. The heated bandage was drawn off the roll, with no sticking problems, and wrapped around the forearm and wrist, passing over the back of the hand, between the thumb and forefinger, across the palm, thence back to the wrist. A series of layers was applied in this manner, taking ~-- 32.
., .. , , . . ~ . -, ~ ~ 3 ~ 1,350 tucks wherever necessary, to build up a sufficient thickness of material to provide support and immobilization of the limb at room temperature. With a slight application of pressure to ensure good surface contact between the overlying layers, the copolymer on the layers fused together so that a unitary cast was formed. When the cast had cooled to room tempera-ture, it was rigid, porous, and contour fitting and held the arm and wrist rigidly in place.
Example 12 To a 350-gallon jacketed reactor there were charged 4,000 lb. of epsilon-caprolactone, 80 lb~ of neopentyl glycol diacrylate, and 7~6 grams of stannous octoate. Trace amounts of water in the reactants were sufficient to act as a poly-merization initiator. The temperature of the reactants was raised to 150C. to start the reaction~ The reaction pro-ceeded for about 16 hours, with an exotherm of 224C. occurrlng after about 5 hours. The viscous product was discharged in strands onto a cooled conveyor belt and the solidiied strands were diced into pellets. The product had a reduced viscosity of 0.5.
Strips of unsized knitted nylon netting, each 4 inches in width and 5 ft. in length (86 s~rands per ft.), were mounted in a fume hood. A 10 weight percent solution ;
of the copolymer produced above, in methylene dichloride, was prepared. There was then added to the solution 10 weight percent titanium dioxide, based on the weight of the copolymer. The solution thus prepared was sprayed on both sides of the nylon netting. After drying overnight, the applied coating weight was about 80 weight percen~ of the ' .
~ 11,350 total weight of the coated netting. The copolymer on the netting was crosslinked by exposure to 3 megarads of electron beam energy from a 2 MEV electron accelerator. The gel content of the crosslinked copolymer on the netting was de~ermined to be 54 weight percent, using a Soxlet extractor.
The strips of netting having the coating of cross-linked copolymer on their strands were employed as an orthopedic cast forming bandage. The strips of bandage were rolled, placed in a 650-watt microwave oven, and heated to a temperature at which the copolymer became sot and moldable. A cloth stockinette was placed over the lower leg and foot. The heated bandage was drawn off the roll and wrapped around the lower leg, ankle, and foot in a series of overlying layers to build up a sufficient thickness of material to provide support and immobilize the limb at room temperature, The overlying layers were fused together by the slight application of pressure to ensure good surface contact. The cast was allowed ~o cool. It formed a rigid, porous cast which held the lower leg and foot in a rigid position. The applied cast had sufficient load-bearing strength to allow the subject to walk on it without bending or breaking it.
'' ' 34~
Claims (19)
1. Process of producing a thermoplastic cross-linkable copolymer which comprises reacting, at a temper ature of from 25 to 300°C., an active-hydrogen containing initiator with a molar excess of a monomer mixture com-prising:
(A) from 90 to 99.5 weight percent of a lactone monomer of the formula wherein n is an integer having a value from about 3 to 61 at least n+2 of the R's are hydrogen, and the remaining R's are each alkyl of 1 to 10 carbon atoms; and (B) from 0.5 to 10 weight percent of a poly-functional acrylate monomer.
(A) from 90 to 99.5 weight percent of a lactone monomer of the formula wherein n is an integer having a value from about 3 to 61 at least n+2 of the R's are hydrogen, and the remaining R's are each alkyl of 1 to 10 carbon atoms; and (B) from 0.5 to 10 weight percent of a poly-functional acrylate monomer.
2. Process for producing a thermoplastic crosslinkable copolymer as claimed in claim 1, wherein said monomer mixture comprises from 95 to 99.5 weight per-cent of said lactone monomer and from 0.5 to 5 weight per-cent of said polyfunctional acrylate monomer.
3. Process for producing a thermoplastic cross-linkable copolymer as claimed in claim 1 wherein said lac-tone is epsilon-caprolactone.
4. Process for producing a thermoplastic crosslinkable copolymer as claimed in claim 3, wherein said polyfunctional acrylate is neopentyl glycol diacrylate.
35.
11,350
35.
11,350
5. Process for producing a thermoplastic crosslinkable copolymer as claimed in claim 3, wherein said polyfunctional acrylate is trimethylolpropane trimethacrylate.
6. Process for producing a thermoplastic crosslinkable copolymer as claimed in claim 3, wherein said polyfunctional acrylate is 3'-acryloxy-2',2'-dimethylpropyl 3-acryloxy-2,2-dimethylpropionate.
7. The thermoplastic crosslinkable copolymer which is produced by the process of claim 1.
8. The thermoplastic crosslinkable copolymer which is produced by the process of claim 2.
9. The thermoplastic crosslinkable copolymer which is produced by the process of claim 3.
10. The thermoplastic crosslinkable copolymer which is produced by the process of claim 4.
11. The thermoplastic crosslinkable copolymer which is produced by the process of claim 5,
12. The thermoplastic crosslinkable copolymer which is produced by the process of claim 6.
13. A thermoplastic crosslinkable copolymer as claimed in claim 7, wherein said thermoplastic crosslinkable copolymer has a reduced viscosity of from 0.1 to 2.
14. Method of producing a thin film which comprises:
(A) exposing the thermoplastic, crosslinkable copolymer of claim 7 to a sufficient amount of ionizing radiation to crosslink the copolymer to a melt index of from 2 to .2 decigrams/min.;
then 36.
11,350 (B) producing a thin film from the crosslinked copolymer by the process of blown-film extrusion.
(A) exposing the thermoplastic, crosslinkable copolymer of claim 7 to a sufficient amount of ionizing radiation to crosslink the copolymer to a melt index of from 2 to .2 decigrams/min.;
then 36.
11,350 (B) producing a thin film from the crosslinked copolymer by the process of blown-film extrusion.
15. The thin film which is produced by the process of claim 14.
16. Method of producing a formed article which comprises the steps of:
(A) exposing the thermoplastic crosslinkable copolymer of claim 7 to from 0.1 to 0.5 megarads of ionizing radiation to reduce its melt index;
(B) extruding a sheet of the crosslinked copoly-mer thus produced;
(C) exposing the extruded sheet to ionizing radiation to further crosslink the copolymer, thereby introducing a gel phase into the copoly-mer and increasing its stiffness;
and then (D) thermoforming the sheet.
(A) exposing the thermoplastic crosslinkable copolymer of claim 7 to from 0.1 to 0.5 megarads of ionizing radiation to reduce its melt index;
(B) extruding a sheet of the crosslinked copoly-mer thus produced;
(C) exposing the extruded sheet to ionizing radiation to further crosslink the copolymer, thereby introducing a gel phase into the copoly-mer and increasing its stiffness;
and then (D) thermoforming the sheet.
17. The formed article produced by the method of claim 16.
18. Thermoplastic crosslinkable copolymer as claimed in claim 7, wherein said copolymer is crosslinkable by exposure to non-ionizing radiation and further comprises from l to 5 weight percent of a photoinitiator.
19. Thermoplastic crosslinkable copolymer as claimed in claim 7, further comprising, in admixture there-with, an organic peroxide in a sufficient amount to pro-mote crosslinking of the copolymer at elevated temperatures.
37.
37.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US880,955 | 1978-02-24 | ||
| US05/880,955 US4175177A (en) | 1978-02-24 | 1978-02-24 | Crosslinkable copolymer of a lactone and a polyfunctional acrylate |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1134992A true CA1134992A (en) | 1982-11-02 |
Family
ID=25377477
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000321670A Expired CA1134992A (en) | 1978-02-24 | 1979-02-16 | Crosslinkable copolymer of a lactone and a polyfunctional acrylate |
Country Status (5)
| Country | Link |
|---|---|
| US (1) | US4175177A (en) |
| EP (1) | EP0003846B1 (en) |
| JP (2) | JPS6030335B2 (en) |
| CA (1) | CA1134992A (en) |
| DE (1) | DE2963872D1 (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4548764A (en) * | 1983-02-23 | 1985-10-22 | International Flavors & Fragrances Inc. | Insect repellent, pheremonal, animal repellent, diagnostic or aroma enhancing compositions containing poly(epsilon caprolactone) having embedded therein functional substances |
Families Citing this family (30)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB1422778A (en) * | 1972-04-10 | 1976-01-28 | Ici Ltd | Shaped polymeric articles |
| US4286586A (en) * | 1979-03-27 | 1981-09-01 | Union Carbide Corporation | Orthopedic devices, materials and methods |
| DE2931737A1 (en) | 1979-08-04 | 1981-02-26 | Basf Ag | METHOD FOR PRODUCING MOLDED BODIES FROM UNSATURATED POLYESTER RESINS |
| US4374077A (en) * | 1980-02-01 | 1983-02-15 | Minnesota Mining And Manufacturing Company | Process for making information carrying discs |
| DE3217653C2 (en) * | 1981-05-11 | 1995-05-18 | Daicel Chem | Process for the preparation of an epsilon-caprolactone-modified vinyl monomer and its use for the preparation of a copolymer |
| JPS59108059A (en) * | 1982-12-09 | 1984-06-22 | Daicel Chem Ind Ltd | Reticulate material structure |
| GB2162527B (en) * | 1984-07-28 | 1988-04-27 | Daicel Chem | Process for producing lactone polymer and thermosetting resin composition containing said lactone polymer as an anti-shrinking agent |
| US5010166A (en) * | 1987-03-05 | 1991-04-23 | S. C. Johnson & Son, Inc. | Process and apparatus for producing polyol polymers and polyol polymers so produced |
| US4921934A (en) * | 1987-12-23 | 1990-05-01 | S. C. Johnson & Son, Inc. | Alkali-soluble polymers and process for producing same |
| US4988763A (en) * | 1988-04-26 | 1991-01-29 | S. C. Johnson & Son, Inc. | Catalyzed bulk process for producing cyclic ester-modified acrylic polymers |
| US5052380A (en) * | 1989-07-07 | 1991-10-01 | Minnesota Mining And Manufacturing Company | Colored orthopedic resins and orthopedic casting materials incorporating same |
| US5185111A (en) * | 1991-02-13 | 1993-02-09 | Polypore, Inc. | Method of producing elastomeric open cell structures |
| NL9101082A (en) * | 1991-06-24 | 1993-01-18 | Tom Paul Marthe Ghislain Ponne | THERMOPLASTIC MATERIAL FOR ORTHOPEDIC AND SURGICAL APPLICATIONS. |
| US5752926A (en) * | 1992-04-29 | 1998-05-19 | Landec Corporation | Orthopedic casts |
| US5378531A (en) * | 1993-07-09 | 1995-01-03 | Larson; Peter M. | Gamma radiation treated sheet material for use as orthopedic splints and casts and the like |
| US5359026A (en) * | 1993-07-30 | 1994-10-25 | Cargill, Incorporated | Poly(lactide) copolymer and process for manufacture thereof |
| GB9518950D0 (en) | 1995-09-15 | 1995-11-15 | Solvay Interox Ltd | Polymers having improved processability |
| US6089009A (en) | 1997-08-28 | 2000-07-18 | Belmont Textile Machinery Co., Inc. | Fluid-jet false-twisting method and product |
| US6201068B1 (en) | 1997-10-31 | 2001-03-13 | Kimberly-Clark Worldwide, Inc. | Biodegradable polylactide nonwovens with improved fluid management properties |
| US6268434B1 (en) | 1997-10-31 | 2001-07-31 | Kimberly Clark Worldwide, Inc. | Biodegradable polylactide nonwovens with improved fluid management properties |
| US6544455B1 (en) | 1997-12-22 | 2003-04-08 | Kimberly-Clark Worldwide, Inc. | Methods for making a biodegradable thermoplastic composition |
| US6309988B1 (en) | 1997-12-22 | 2001-10-30 | Kimberly-Clark Worldwide, Inc. | Biodisintegratable nonwovens with improved fluid management properties |
| US6306782B1 (en) | 1997-12-22 | 2001-10-23 | Kimberly-Clark Worldwide, Inc. | Disposable absorbent product having biodisintegratable nonwovens with improved fluid management properties |
| US6372850B2 (en) | 1997-12-31 | 2002-04-16 | Kimberly-Clark Worldwide, Inc. | Melt processable poly (ethylene oxide) fibers |
| EP0984039A4 (en) * | 1998-03-12 | 2002-01-02 | Daicel Chem | Lactone-containing resin composition, molded object thereof, and film |
| US6197860B1 (en) | 1998-08-31 | 2001-03-06 | Kimberly-Clark Worldwide, Inc. | Biodegradable nonwovens with improved fluid management properties |
| US6194483B1 (en) | 1998-08-31 | 2001-02-27 | Kimberly-Clark Worldwide, Inc. | Disposable articles having biodegradable nonwovens with improved fluid management properties |
| EP2023941B1 (en) | 2006-04-24 | 2016-12-21 | Incept, LLC | Protein crosslinkers, crosslinking methods and applications thereof |
| BE1020363A3 (en) * | 2011-12-23 | 2013-08-06 | Orfit Ind | METHOD FOR MANUFACTURING A POLYMER SHEET FOR USE AS AN IMMOBILIZATION ELEMENT. |
| CN111303395B (en) * | 2020-04-07 | 2022-08-19 | 青岛科技大学 | Preparation method of low molecular weight polycaprolactone |
Family Cites Families (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3795701A (en) * | 1972-02-07 | 1974-03-05 | Laporte Industries Ltd | Copolymers of epoxides and lactones |
| DE2310307C2 (en) * | 1973-03-01 | 1983-12-29 | Hoechst Ag, 6230 Frankfurt | Photosensitive recording material |
| US3855357A (en) * | 1973-08-03 | 1974-12-17 | Union Carbide Corp | Wire and cable insulation comprising vinyl chloridepolymer and lactone graft copolymer |
| GB1443073A (en) * | 1974-01-11 | 1976-07-21 | Interox Chemicals Ltd | Method of preparing copolymers |
| GB1564296A (en) * | 1975-09-30 | 1980-04-02 | Mobil Oil Corp | Radiation curable coating compositions |
| CA1070201A (en) | 1975-11-19 | 1980-01-22 | Kenneth M. Holland | Moldable plastic orthopedic cast |
-
1978
- 1978-02-24 US US05/880,955 patent/US4175177A/en not_active Expired - Lifetime
-
1979
- 1979-02-16 CA CA000321670A patent/CA1134992A/en not_active Expired
- 1979-02-23 EP EP79100554A patent/EP0003846B1/en not_active Expired
- 1979-02-23 JP JP54019858A patent/JPS6030335B2/en not_active Expired
- 1979-02-23 DE DE7979100554T patent/DE2963872D1/en not_active Expired
-
1985
- 1985-02-26 JP JP60035439A patent/JPS60236725A/en active Granted
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4548764A (en) * | 1983-02-23 | 1985-10-22 | International Flavors & Fragrances Inc. | Insect repellent, pheremonal, animal repellent, diagnostic or aroma enhancing compositions containing poly(epsilon caprolactone) having embedded therein functional substances |
Also Published As
| Publication number | Publication date |
|---|---|
| JPS54154495A (en) | 1979-12-05 |
| EP0003846A1 (en) | 1979-09-05 |
| JPS6336926B2 (en) | 1988-07-22 |
| US4175177A (en) | 1979-11-20 |
| DE2963872D1 (en) | 1982-11-25 |
| JPS6030335B2 (en) | 1985-07-16 |
| EP0003846B1 (en) | 1982-10-20 |
| JPS60236725A (en) | 1985-11-25 |
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