CA1082835A - Epoxy resin powder including ethylene-vinyl acetate copolymer - Google Patents
Epoxy resin powder including ethylene-vinyl acetate copolymerInfo
- Publication number
- CA1082835A CA1082835A CA257,525A CA257525A CA1082835A CA 1082835 A CA1082835 A CA 1082835A CA 257525 A CA257525 A CA 257525A CA 1082835 A CA1082835 A CA 1082835A
- Authority
- CA
- Canada
- Prior art keywords
- powder
- weight
- copolymer
- parts
- polyglycidyl ether
- 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
Links
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
- C08G59/00—Polycondensates containing more than one epoxy group per molecule; Macromolecules obtained by polymerising compounds containing more than one epoxy group per molecule using curing agents or catalysts which react with the epoxy groups
- C08G59/18—Macromolecules obtained by polymerising compounds containing more than one epoxy group per molecule using curing agents or catalysts which react with the epoxy groups ; e.g. general methods of curing
- C08G59/40—Macromolecules obtained by polymerising compounds containing more than one epoxy group per molecule using curing agents or catalysts which react with the epoxy groups ; e.g. general methods of curing characterised by the curing agents used
- C08G59/4007—Curing agents not provided for by the groups C08G59/42 - C08G59/66
- C08G59/4014—Nitrogen containing compounds
- C08G59/4035—Hydrazines; Hydrazides
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
- C08K5/00—Use of organic ingredients
- C08K5/16—Nitrogen-containing compounds
- C08K5/22—Compounds containing nitrogen bound to another nitrogen atom
- C08K5/24—Derivatives of hydrazine
- C08K5/25—Carboxylic acid hydrazides
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
- C08L23/00—Compositions of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Compositions of derivatives of such polymers
- C08L23/02—Compositions of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Compositions of derivatives of such polymers not modified by chemical after-treatment
- C08L23/04—Homopolymers or copolymers of ethene
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
- C08L31/00—Compositions of homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by an acyloxy radical of a saturated carboxylic acid, of carbonic acid or of a haloformic acid; Compositions of derivatives of such polymers
- C08L31/02—Homopolymers or copolymers of esters of monocarboxylic acids
- C08L31/04—Homopolymers or copolymers of vinyl acetate
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
- C08L63/00—Compositions of epoxy resins; Compositions of derivatives of epoxy resins
-
- C—CHEMISTRY; METALLURGY
- C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
- C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
- C09D163/00—Coating compositions based on epoxy resins; Coating compositions based on derivatives of epoxy resins
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
- Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
- Y10T428/00—Stock material or miscellaneous articles
- Y10T428/31504—Composite [nonstructural laminate]
- Y10T428/31511—Of epoxy ether
- Y10T428/31529—Next to metal
Abstract
ABSTRACT
Stable, free-flowing epoxy resin powder which fuses to and cures upon striking an object which has been preheated to the curing temperature of the composition of the powder to provide a tough protective coating. The composition differs from the prior art in that it includes 3-30 parts of a copolymer of 2-50% vinyl acetate and 5-75%
ethylene per 100 parts of the epoxy resin. The copolymer improves the flexibility of the cured coatings.
Stable, free-flowing epoxy resin powder which fuses to and cures upon striking an object which has been preheated to the curing temperature of the composition of the powder to provide a tough protective coating. The composition differs from the prior art in that it includes 3-30 parts of a copolymer of 2-50% vinyl acetate and 5-75%
ethylene per 100 parts of the epoxy resin. The copolymer improves the flexibility of the cured coatings.
Description
108~ 912,401 EPOXY RESIN POWDER INCLUDING
ETHYLENE-VINYL ACETATE COPOLYMER
Thls inventlon concerns epoxy resin powder used to provlde protectlve coatings, especially for petroleum pipe-llnes.
Thermosetting epoxy resln powders are widely used to provlde protectlve coatlngs, especlally for steel plpe.
The coatlngs may be applled by blowing the powder onto pipe whlch has been preheated to a temperature above the softening point of the powder so that the powder fuses and adheres to the pipe. The pipe may then be carried to an oven to cure the resin, or if the pipe contains sufficient heat, the resin fully cures before the pipe has cooled to room temperature.
The cured coatings should be sufficiently adherent and flexible to withstand the bending ar.dimpact to which the pipe or other substrate may be sub~ected during shlpment and installation. Insufflcient flexibility becomes especially troublesome ln cold weather. In use, the cured coatings should be resistant to the most adverse conditions that may be encountered. For example, cured coatings are sub~ect to disbondment due to the cathodic protection which is commonly applied to buried pipe, a condition aggravated in hot service, especially when the pipe is buried in moist ground.
For commercial utility, it is necessary that the uncured powder be stable at room temperature. Upon strlking the heated substrate, the uncured powder must fuse and flow sufflciently to provide pinhole-free coatings, but should cure to a thermoset state quickly at moderately elevated temperature to permit the coatings to be applied at reason-ably high rates of production. For some applications the coatings should harden at the curing temperature sufficiently to permit handling wlthln ten seconds, although longer times ~O~Z835 are satisfactory in many applications.
The powder of the present invention is shelf-stable and provides cured protective coatings that exhibit extraordinarily good flexibility, cspocially at sub-freezing temperatures, while affording other protective propcrties equal to results with epoxy resin powders now on the market.
This invention provides for a homogeneous free-flowing powder which is shelf-stable and when heated to 185-250C in contact with a metal article fuses and then gels to provide a tough protective coating, said powder comprising a polyglycidyl ether of a polyhydric phenol having a softening point of 70-150C, a normally solid latent hardening agent for epoxy resin, a latent catalyst for accelerating reaction between the polyglycidyl ether and the hardening agent when melted together, which powder is characterized by the feature that it incorporates per 100 parts of the polyglycidyl ether 3-30 parts by weight of one or more copolymers of monomers comprising by weight 2-50% vinyl acetate and 5-75%
ethylene, which copolymer or copolymers have a melt index or combined melt index of 5-400 and impart extraordinarily good flexibility to cured coatings of the powder without undue effect upcn other properties of the coatings.
In an aspect of the invention, this invention seeks to provide method of making a thermosetting powder, which method comprises the steps of (1) blending together 100 parts by weight of a polyglycidyl ether of a polyhydric phenol having a softening point of 70-150C and 3-30 parts by weight of one or more copolymers of monomers comprising by weight 2-50%
vinyl acetate and 5-75% ethylene to provide a homogeneous blend,
ETHYLENE-VINYL ACETATE COPOLYMER
Thls inventlon concerns epoxy resin powder used to provlde protectlve coatings, especially for petroleum pipe-llnes.
Thermosetting epoxy resln powders are widely used to provlde protectlve coatlngs, especlally for steel plpe.
The coatlngs may be applled by blowing the powder onto pipe whlch has been preheated to a temperature above the softening point of the powder so that the powder fuses and adheres to the pipe. The pipe may then be carried to an oven to cure the resin, or if the pipe contains sufficient heat, the resin fully cures before the pipe has cooled to room temperature.
The cured coatings should be sufficiently adherent and flexible to withstand the bending ar.dimpact to which the pipe or other substrate may be sub~ected during shlpment and installation. Insufflcient flexibility becomes especially troublesome ln cold weather. In use, the cured coatings should be resistant to the most adverse conditions that may be encountered. For example, cured coatings are sub~ect to disbondment due to the cathodic protection which is commonly applied to buried pipe, a condition aggravated in hot service, especially when the pipe is buried in moist ground.
For commercial utility, it is necessary that the uncured powder be stable at room temperature. Upon strlking the heated substrate, the uncured powder must fuse and flow sufflciently to provide pinhole-free coatings, but should cure to a thermoset state quickly at moderately elevated temperature to permit the coatings to be applied at reason-ably high rates of production. For some applications the coatings should harden at the curing temperature sufficiently to permit handling wlthln ten seconds, although longer times ~O~Z835 are satisfactory in many applications.
The powder of the present invention is shelf-stable and provides cured protective coatings that exhibit extraordinarily good flexibility, cspocially at sub-freezing temperatures, while affording other protective propcrties equal to results with epoxy resin powders now on the market.
This invention provides for a homogeneous free-flowing powder which is shelf-stable and when heated to 185-250C in contact with a metal article fuses and then gels to provide a tough protective coating, said powder comprising a polyglycidyl ether of a polyhydric phenol having a softening point of 70-150C, a normally solid latent hardening agent for epoxy resin, a latent catalyst for accelerating reaction between the polyglycidyl ether and the hardening agent when melted together, which powder is characterized by the feature that it incorporates per 100 parts of the polyglycidyl ether 3-30 parts by weight of one or more copolymers of monomers comprising by weight 2-50% vinyl acetate and 5-75%
ethylene, which copolymer or copolymers have a melt index or combined melt index of 5-400 and impart extraordinarily good flexibility to cured coatings of the powder without undue effect upcn other properties of the coatings.
In an aspect of the invention, this invention seeks to provide method of making a thermosetting powder, which method comprises the steps of (1) blending together 100 parts by weight of a polyglycidyl ether of a polyhydric phenol having a softening point of 70-150C and 3-30 parts by weight of one or more copolymers of monomers comprising by weight 2-50%
vinyl acetate and 5-75% ethylene to provide a homogeneous blend,
(2) mixing with said blend a normally solid latent hardening agent for epoxy resin and a latent catalyst for accelerating reaction between the polyglycidyl ether and the hardening agent, and
(3) pulverizing the mixture to provide a free-flowing powder which is shelf-stable and when heated to 185-250C in contact with a metal article fuses and then gels to provide a tough protective coating.
~ - 2 -~' J
1(~8Z835 The improved flexibility is realized by including one or more copolymers, each of which is a copolymer of monomers comprising by weight 2-50% vinyl acetate and 5-75% ethylene, preferably 25-50 weight percent v;nyl acetate and 50-75 weight pcrcent ethylene. Surprisingly, thc presence of the copolymer or copolymers appears to involve the additional improvement of better flow characteristics, thus tending to avoid coating imperfections which have occurred using powder of identical compositions except for omission of the copolymer or copolymers. For optimum flow characteristics, the melt index of the copolymer or combined melt index of the copolymers should exceed 5. At a melt index above 400, significant improvement in bendability has not been attained. Cured coatings having both good flexibility and freedom from coating imperfections are most readily attained by employing one or more copolymers of ethylene and vinyl acetate which have a melt index or combined melt index of 20-200.
- 2a -.
~082~35 In addltlon to vinyl acetate and ethylene, the copolymer may be based on up to 60 weight percent of other copolymerizable monomers which do not interfere with the dlspersibility into and the stability of the uncured epoxy 5 resln composition, e.g., vlnyl chlorlde and/or very small amounts of organic aclds such as maleic acid or acrylic acid.
However, best results have been attained where more than 98 weight percent of the monomers are ethylene and vinyl acetate.
Improved flexibility is observable from the use of only three parts of ethylene-vinyl acetate copolymer per 100 parts by weight of polyglycidyl ether. Increased amounts of copolymer produce cured coatings of even greater flexi-bility, but at over 30 parts, other desirable performance levels may not be realized. For most purposes, 3 to 10 parts of copolymer are preferred. At over 10 parts, it may be nece~sary to take steps to avold stlcklness ln the uncured composltlon, as by employlng a polyglycldyl ether which has a softenlng polnt of at least 90C or by incorporatlng a fluldlzlng ald such as fumed silica. Stickiness must be avoided so that the composition can be pulverized to provide a free-flowing powder, most of which will pass a screen having 180-micrometer openings.
The preferred polyglycidyl ethers are those ob-tained by condensing epichlorohydrin and 2,2'-bis(hydroxy-phenyl)propane (bisphenol A). Other polyhydric phenolswhich provide usefully high-melting polyglycidyl ethers include phenol novolaks and ortho-cresol novolaks. For convenience in obtaining a blend of the ethylene-vlnyl acetate copolymer and a high-melting polyglycidyl ether, it is preferred to begin with a mixture of the copolymer and a liquid polyglycidyl ether together with materials for _3_ J.08283S
advancing the polyglycidyl ether to a molecular weight providing a softenlng point of 70C or more, after which the hardening ay;ent and catalyst are added.
The novel powder may employ any latent hardenlng ag'ent known to provlde room-temperature-8table epoxy coating powders. Among these are methylene dianiline, dicyandiamlde and dihydrazides of the formula O O
ll ll where R is a divalent hydrocarbon radical of at least two carbon atoms, preferably at least four carbon atoms. Adipic, azelaic and isophthalic dihydrazide are particularly useful.
Any anhydride disclosed in U. S. patent No. 3,578,615 (Moore) may be used, especially trimellitic anhydride and adducts thereof.
For most appllcatlons, the latent catalyst should be so selected that the composltlon wlll harden at ordinary curlng temperatures (usually 185-250C) at a rate permitting the coated ob~ect to be handled within a minute or even as soon as a few seconds. When using trimellitic anhydride, stannous octoate is a particularly suitable catalyst.
Various additives such as flow control agents and pigments and other fillers can be added for the same purposes and effect as they are used in epoxy coating powders of the prior art.
Except as otherwise indicated below, specimens for testing are made by coating a steel panel or bar which has been sandblasted, degreased and then preheated in an oven to about 230C. Powder is blown onto the panel and 30 fuses to provide a coating of about 0.3 mm in thickness which is cured by residual heat in the steel without any 108Z~35 post-heating, except that the panels for the Impact Test were returned to the oven for three minutes because they did not hold sufficient heat to cure the resin. In all test results reported below, the coatlng thickness was within the range of 0.25 to 0.4 mm except as noted.
Bend Test A coated steel bar 17.5 x 2.5 x 1.0 cm ls bent in the easy direction around mandrels of successively smaller radii, beginning at 30 diameters and decreasing five dia-meters each time except that a specimen which passes tendiameters is finally tested at eight diameters. A coating which passes eight diameters has exceedingly good flexibility for coating steel pipe. "X" diameters means that the radius of the mandrel is X times the thickness of the bar. While the coating is wet with tap water, 1500 volts DC are applied across the entire coated surface except at the edges. If an electrlcal breakdown fallure ls due to a plnhole ln the coatlng, this is attributed to nonunlform coatlng, and the test ls contlnued until there is a failure due to cracking or stress marks.
Impact Test Coated steel panels measuring 7.5 x 7.5 x 0.3 cm, after cooling to room temperature, are placed in the Gardner Impact Tester. A 4-pound (1.8-kg) weight having a striker with a curved end of 1.6 cm diameter is allowed to fall a predetermined distance up to 40 inches (102 cm). Failure is determined as in the Bend Test with the electrode at the impact area.
60C Cathodic Disbondment Test In a coated steel panel measuring 15 x 15 x 1 cm, a hole 3 mm in diameter is drilled through the coating and 1(~82~35 1.5 mm into thc pancl. A piece of 10-cm plastic pipe is aclhosivcly bonded to the coating to provide a fluid-tight container with the hole at the center of the flat base of the container. Ihe container is filled with an aqueous solution of 1% NaCl, 1% Na2S04 and 1% Na2C03. With the container in an oven at 60C, 6 volts DC are applied between the steel panel and a platinum electrode immersed in the solution to provide cathodic protection. After seven days, the solu-tion is poured off, and any disbonded resin is scraped away with a sharp knife, leaving an uncoated circle, the diameter of which is measured. Occasionally disbondment occurs out-side the drilled hole in the form of blisters or star-like cracks due to coating imperfections.
Epoxy Resins "Epoxy Resin A" is a polyglycidyl ether of 2,2'-bis(4-hydroxyphenyl)propane (bisphenol A) having a Durrans' softening point of 95-105C and an epoxide equiva-lent of 870-1025. Such an epoxy resin is presently marketed by Shell Chemical Corp. as "Epon" 1004.*
"Epoxy Resin B" is a polyglycidyl ether of bis-phenol A having a Durrans' softening point of 8-12C and an epoxide equivalent weight of 180-195, e.g., "Epon" 828.
Copolymers I-VI
Copolymers I-VI are copolymers of vinyl acetate and ethylene. Copolymers IV-VI are also based on about one percent organic acid monomer, believed to be acrylic acid or maleic acid.
*Trade Mark ~08Z835 Table I
Approxlmate Percent Copolymer by Weight Melt Index Vinyl Acetate Ethylene - 10 Example 1 Time of Addltion Grams(minutes) ~ -Epoxy Resin A ................................ 150 -Copolymer I .................................10.5 Crystalline sllica powder ...................21.3 5 Fl~w-control agent (polymerized ethyl acrylate-long chain hydrocarbon) .....Ø9 5 2,4,6-tris(dimethylaminomethyl)-phenol ...................................... 2.0 10 ~ -Trimellitic anhydride .......................28.5 15 Using a 2-roll rubber mill, one roll of which was heated by steam to about lOO~C while the other was maintained at ambient temperature, the Epoxy Resin A was banded and the other ingredients were added at the approximate tlmes indicated above. Mixing of the catalyst and anhydride was enhanced - by making cuts in the banded material and remilling this.
After a total of about 18 minutes, the sheet was removed, allowed to cool to room temperature, and ground to a fine powder which was sieved through No. 80 mesh screen (U. S.) having 180-micrometer openings.
Upon striking a steel panel preheated to 205C, .
1~82~35 thls powder gelled in seven seconds.
In the 60C Cathodic Disbondment Test, the dis-bondment area had a diameter of 1.2 cm, an excellent value.
There were no areas of extraneous disbondment.
5Com~arative Example lA
Example 1 was repeated except that Copolymer I was omitted for purposes of comparison.
Example 2 Example l was repeated except reducing the amount of Copolymer I to 7.5 grams.
Example 3 Example l was repeated except increaslng the amount of Copolymer I to 30 grams.
Tests of cured coatings of Examples 1, lA, 2 and 3 are recorded in Table II.
Table II
Bend Test Impact Test t2 or 3 bars (160-inch-pounds) Example tested) (1.8-kg-m) l Passed 8 diameters Passed Failed 8 diameters lA Failed 30 diameters Failed Failed 30 diameters 2 Failed 10 diameters Passed Failed 25 diameters 3 Failed 8 diameters Failed Failed lO diameters Failed 25 diameter Although Examples l and 2 of the present invention exhibited better resistance to impact than did Comparative Example lA, cured coatings of the present invention in the 1082~35 Impact Test generally do not outperform, and often are some-what inferlor to, otherwise ldentical coatlngs except for omlssion of any ethylene-vinyl acetate copolymer. On the other hand, the presence of the copolymer lnvarlably produces slgnlricant lmprovement in the Bend Test while retainlng reasonably good reslstance to lmpact. It also tends to lmprove flow propertles, thus providing coatings which are free from thickness dlscontlnuities and pinholes which have been a source of considerable concern in the prior art.
Examples 4-16 Essentially the procedure of Example 1 was followed to produce the compositions identlfled in Table III. Example 4A provides a control. Each of the powders gelled in about eight seconds after contacting a steel bar at 205C.
..
~08Z~35 Table III
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., t~ l Ot~
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~ ~ .D
O n ~ ~~ . ~ ~ 30 ~ I I I O II ~D ~ N ~ Ltl Ltl O O 1~ 0 C~
`D5)~1 ~1 1~ N~ _I _I N ~
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. Il~00 ~ ~D 3 _~ g ,1~ _ ~~ O ~ 11 O1~ ~ .. . . ~, I I II I~ ~) N`DIJ') O O In 11~ *
O~
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N ~) N
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C ~ H ~ O ¢ON ~N Cd O O H H H ~ ~ H N ~ ~ rO 0 Xu~h ~ ~00 ~ ~ ~ ~d ~ O E~
Ct~g ~ ~ X~ ~ ~ h h C~ O ~ Oo n~ h E-- h ~ 0 ~ 0 ~ .C ~0~ N ~ N~ Z O
X3 - O ~~ D
OO --' ~h h ~ h0 ~d O0 ~d O 00 0 C~ ~ h W ~ ~ ~H U~ ~ *
~ - 2 -~' J
1(~8Z835 The improved flexibility is realized by including one or more copolymers, each of which is a copolymer of monomers comprising by weight 2-50% vinyl acetate and 5-75% ethylene, preferably 25-50 weight percent v;nyl acetate and 50-75 weight pcrcent ethylene. Surprisingly, thc presence of the copolymer or copolymers appears to involve the additional improvement of better flow characteristics, thus tending to avoid coating imperfections which have occurred using powder of identical compositions except for omission of the copolymer or copolymers. For optimum flow characteristics, the melt index of the copolymer or combined melt index of the copolymers should exceed 5. At a melt index above 400, significant improvement in bendability has not been attained. Cured coatings having both good flexibility and freedom from coating imperfections are most readily attained by employing one or more copolymers of ethylene and vinyl acetate which have a melt index or combined melt index of 20-200.
- 2a -.
~082~35 In addltlon to vinyl acetate and ethylene, the copolymer may be based on up to 60 weight percent of other copolymerizable monomers which do not interfere with the dlspersibility into and the stability of the uncured epoxy 5 resln composition, e.g., vlnyl chlorlde and/or very small amounts of organic aclds such as maleic acid or acrylic acid.
However, best results have been attained where more than 98 weight percent of the monomers are ethylene and vinyl acetate.
Improved flexibility is observable from the use of only three parts of ethylene-vinyl acetate copolymer per 100 parts by weight of polyglycidyl ether. Increased amounts of copolymer produce cured coatings of even greater flexi-bility, but at over 30 parts, other desirable performance levels may not be realized. For most purposes, 3 to 10 parts of copolymer are preferred. At over 10 parts, it may be nece~sary to take steps to avold stlcklness ln the uncured composltlon, as by employlng a polyglycldyl ether which has a softenlng polnt of at least 90C or by incorporatlng a fluldlzlng ald such as fumed silica. Stickiness must be avoided so that the composition can be pulverized to provide a free-flowing powder, most of which will pass a screen having 180-micrometer openings.
The preferred polyglycidyl ethers are those ob-tained by condensing epichlorohydrin and 2,2'-bis(hydroxy-phenyl)propane (bisphenol A). Other polyhydric phenolswhich provide usefully high-melting polyglycidyl ethers include phenol novolaks and ortho-cresol novolaks. For convenience in obtaining a blend of the ethylene-vlnyl acetate copolymer and a high-melting polyglycidyl ether, it is preferred to begin with a mixture of the copolymer and a liquid polyglycidyl ether together with materials for _3_ J.08283S
advancing the polyglycidyl ether to a molecular weight providing a softenlng point of 70C or more, after which the hardening ay;ent and catalyst are added.
The novel powder may employ any latent hardenlng ag'ent known to provlde room-temperature-8table epoxy coating powders. Among these are methylene dianiline, dicyandiamlde and dihydrazides of the formula O O
ll ll where R is a divalent hydrocarbon radical of at least two carbon atoms, preferably at least four carbon atoms. Adipic, azelaic and isophthalic dihydrazide are particularly useful.
Any anhydride disclosed in U. S. patent No. 3,578,615 (Moore) may be used, especially trimellitic anhydride and adducts thereof.
For most appllcatlons, the latent catalyst should be so selected that the composltlon wlll harden at ordinary curlng temperatures (usually 185-250C) at a rate permitting the coated ob~ect to be handled within a minute or even as soon as a few seconds. When using trimellitic anhydride, stannous octoate is a particularly suitable catalyst.
Various additives such as flow control agents and pigments and other fillers can be added for the same purposes and effect as they are used in epoxy coating powders of the prior art.
Except as otherwise indicated below, specimens for testing are made by coating a steel panel or bar which has been sandblasted, degreased and then preheated in an oven to about 230C. Powder is blown onto the panel and 30 fuses to provide a coating of about 0.3 mm in thickness which is cured by residual heat in the steel without any 108Z~35 post-heating, except that the panels for the Impact Test were returned to the oven for three minutes because they did not hold sufficient heat to cure the resin. In all test results reported below, the coatlng thickness was within the range of 0.25 to 0.4 mm except as noted.
Bend Test A coated steel bar 17.5 x 2.5 x 1.0 cm ls bent in the easy direction around mandrels of successively smaller radii, beginning at 30 diameters and decreasing five dia-meters each time except that a specimen which passes tendiameters is finally tested at eight diameters. A coating which passes eight diameters has exceedingly good flexibility for coating steel pipe. "X" diameters means that the radius of the mandrel is X times the thickness of the bar. While the coating is wet with tap water, 1500 volts DC are applied across the entire coated surface except at the edges. If an electrlcal breakdown fallure ls due to a plnhole ln the coatlng, this is attributed to nonunlform coatlng, and the test ls contlnued until there is a failure due to cracking or stress marks.
Impact Test Coated steel panels measuring 7.5 x 7.5 x 0.3 cm, after cooling to room temperature, are placed in the Gardner Impact Tester. A 4-pound (1.8-kg) weight having a striker with a curved end of 1.6 cm diameter is allowed to fall a predetermined distance up to 40 inches (102 cm). Failure is determined as in the Bend Test with the electrode at the impact area.
60C Cathodic Disbondment Test In a coated steel panel measuring 15 x 15 x 1 cm, a hole 3 mm in diameter is drilled through the coating and 1(~82~35 1.5 mm into thc pancl. A piece of 10-cm plastic pipe is aclhosivcly bonded to the coating to provide a fluid-tight container with the hole at the center of the flat base of the container. Ihe container is filled with an aqueous solution of 1% NaCl, 1% Na2S04 and 1% Na2C03. With the container in an oven at 60C, 6 volts DC are applied between the steel panel and a platinum electrode immersed in the solution to provide cathodic protection. After seven days, the solu-tion is poured off, and any disbonded resin is scraped away with a sharp knife, leaving an uncoated circle, the diameter of which is measured. Occasionally disbondment occurs out-side the drilled hole in the form of blisters or star-like cracks due to coating imperfections.
Epoxy Resins "Epoxy Resin A" is a polyglycidyl ether of 2,2'-bis(4-hydroxyphenyl)propane (bisphenol A) having a Durrans' softening point of 95-105C and an epoxide equiva-lent of 870-1025. Such an epoxy resin is presently marketed by Shell Chemical Corp. as "Epon" 1004.*
"Epoxy Resin B" is a polyglycidyl ether of bis-phenol A having a Durrans' softening point of 8-12C and an epoxide equivalent weight of 180-195, e.g., "Epon" 828.
Copolymers I-VI
Copolymers I-VI are copolymers of vinyl acetate and ethylene. Copolymers IV-VI are also based on about one percent organic acid monomer, believed to be acrylic acid or maleic acid.
*Trade Mark ~08Z835 Table I
Approxlmate Percent Copolymer by Weight Melt Index Vinyl Acetate Ethylene - 10 Example 1 Time of Addltion Grams(minutes) ~ -Epoxy Resin A ................................ 150 -Copolymer I .................................10.5 Crystalline sllica powder ...................21.3 5 Fl~w-control agent (polymerized ethyl acrylate-long chain hydrocarbon) .....Ø9 5 2,4,6-tris(dimethylaminomethyl)-phenol ...................................... 2.0 10 ~ -Trimellitic anhydride .......................28.5 15 Using a 2-roll rubber mill, one roll of which was heated by steam to about lOO~C while the other was maintained at ambient temperature, the Epoxy Resin A was banded and the other ingredients were added at the approximate tlmes indicated above. Mixing of the catalyst and anhydride was enhanced - by making cuts in the banded material and remilling this.
After a total of about 18 minutes, the sheet was removed, allowed to cool to room temperature, and ground to a fine powder which was sieved through No. 80 mesh screen (U. S.) having 180-micrometer openings.
Upon striking a steel panel preheated to 205C, .
1~82~35 thls powder gelled in seven seconds.
In the 60C Cathodic Disbondment Test, the dis-bondment area had a diameter of 1.2 cm, an excellent value.
There were no areas of extraneous disbondment.
5Com~arative Example lA
Example 1 was repeated except that Copolymer I was omitted for purposes of comparison.
Example 2 Example l was repeated except reducing the amount of Copolymer I to 7.5 grams.
Example 3 Example l was repeated except increaslng the amount of Copolymer I to 30 grams.
Tests of cured coatings of Examples 1, lA, 2 and 3 are recorded in Table II.
Table II
Bend Test Impact Test t2 or 3 bars (160-inch-pounds) Example tested) (1.8-kg-m) l Passed 8 diameters Passed Failed 8 diameters lA Failed 30 diameters Failed Failed 30 diameters 2 Failed 10 diameters Passed Failed 25 diameters 3 Failed 8 diameters Failed Failed lO diameters Failed 25 diameter Although Examples l and 2 of the present invention exhibited better resistance to impact than did Comparative Example lA, cured coatings of the present invention in the 1082~35 Impact Test generally do not outperform, and often are some-what inferlor to, otherwise ldentical coatlngs except for omlssion of any ethylene-vinyl acetate copolymer. On the other hand, the presence of the copolymer lnvarlably produces slgnlricant lmprovement in the Bend Test while retainlng reasonably good reslstance to lmpact. It also tends to lmprove flow propertles, thus providing coatings which are free from thickness dlscontlnuities and pinholes which have been a source of considerable concern in the prior art.
Examples 4-16 Essentially the procedure of Example 1 was followed to produce the compositions identlfled in Table III. Example 4A provides a control. Each of the powders gelled in about eight seconds after contacting a steel bar at 205C.
..
~08Z~35 Table III
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Claims (7)
1. A homogeneous free-flowing powder which is shelf-stable and when heated to 185°-250°C in contact with a metal article fuses and then gels to provide a tough protec-tive coating, said powder comprising a polyglycidyl ether of a polyhydric phenol having a aoftening point of 70°-150°C, a normally solid latent hardening agent for epoxy resin, a latent catalyst for accelerating reaction between the polyglycidyl ether and the hardening agent when melted together, which powder is characterized by the feature that it incorporates per 100 parts of the polyglycidyl ether 3-30 parts by weight of one or more copolymers of monomers comprising by weight 2-50% vinyl acetate and 5-75% ethylene, which copolymer or copolymers have a melt index or combined melt index of 5-400 and impart extraordinarily good flexibility to cured coatings of the powder without undue effect upon other properties of the coatings.
2. A powder as defined in claim 1 wherein a said copolymer is a copolymer of 25-50 weight percent of vinyl acetate and 50-75 weight percent of ethylene.
3. A powder as defined in claims 1 or 2 wherein a said copolymer is also based on about one weight percent of acrylic acid or maleic acid.
4. A powder as defined in claim 1 wherein the composition includes 3-10 parts by weight of said copolymer or copolymers per 100 parts of the polyglycidyl ether.
5. A powder as defined in claim 1 wherein said one or more copolymers have a melt index or combined melt index of 20-200.
6. A powder as defined in claim 1, most of which will pass a screen having 180-micrometer openings.
7. Method of making a thermosetting powder, which method comprises the steps of (1) blending together 100 parts by weight of a polyglycidyl ether of a polyhydric phenol having a softening point of 70°-150°C and 3-30 parts by weight of one or more copolymers of monomers comprising by weight 2-50%
vinyl acetate and 5-75% ethylene to provide a homo-geneous blend, (2) mixing with said blend a normally solid latent hardening agent for epoxy resin and a latent catalyst for acceler-ating reaction between the polyglycidyl ether and the hardening agent, and (3) pulverizing the mixture to provide a free-flowing powder which is shelf-stable and when heated to 185°-250°C in contact with a metal article fuses and then gels to provide a tough protective coating.
vinyl acetate and 5-75% ethylene to provide a homo-geneous blend, (2) mixing with said blend a normally solid latent hardening agent for epoxy resin and a latent catalyst for acceler-ating reaction between the polyglycidyl ether and the hardening agent, and (3) pulverizing the mixture to provide a free-flowing powder which is shelf-stable and when heated to 185°-250°C in contact with a metal article fuses and then gels to provide a tough protective coating.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US05/603,702 US4009224A (en) | 1975-08-11 | 1975-08-11 | Epoxy resin powder including ethylene vinyl acetate |
| US603,702 | 1975-08-11 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1082835A true CA1082835A (en) | 1980-07-29 |
Family
ID=24416567
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA257,525A Expired CA1082835A (en) | 1975-08-11 | 1976-07-22 | Epoxy resin powder including ethylene-vinyl acetate copolymer |
Country Status (4)
| Country | Link |
|---|---|
| US (1) | US4009224A (en) |
| JP (1) | JPS5237963A (en) |
| CA (1) | CA1082835A (en) |
| DE (1) | DE2636394A1 (en) |
Families Citing this family (26)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS4966511A (en) * | 1972-10-30 | 1974-06-27 | ||
| US4017447A (en) * | 1975-09-08 | 1977-04-12 | W. R. Grace & Co. | Flow control agent for ultra thin epoxy resin powder coatings |
| JPS5817783B2 (en) * | 1976-07-08 | 1983-04-09 | 日本曹達株式会社 | Hetero-macrocyclic compounds supported on solid surfaces |
| US4113681A (en) * | 1977-05-10 | 1978-09-12 | E. I. Du Pont De Nemours And Company | Thermoplastic polyvinyl chloride-acrylic powder coating composition |
| US4254071A (en) * | 1978-12-18 | 1981-03-03 | General Electric Company | Method of preparing electrostatic coating compositions containing an epoxy resin |
| US4349645A (en) * | 1981-08-05 | 1982-09-14 | Minnesota Mining And Manufacturing Company | Powdered blend of epoxy resin and anhydride containing hindered nitrogen-containing compound |
| JPS6019655U (en) * | 1983-07-19 | 1985-02-09 | 株式会社 三ツ葉電機製作所 | car door lock device |
| US4524107A (en) * | 1984-03-20 | 1985-06-18 | Westinghouse Electric Corp. | Toughened thermoset laminates |
| US5095046A (en) * | 1990-02-06 | 1992-03-10 | Exxon Chemical Patents Inc. | Hot melt adhesive of ethylene/unsaturated acid copolymer and epoxy crosslinker |
| US5344883A (en) * | 1992-10-05 | 1994-09-06 | Alliedsignal Inc. | Polymeric powder coating compositions comprising low molecular weight copolymer or terpolymer salts of α-olefins and α,β-ethylenically unsaturated carboxylic acids |
| US5470912A (en) * | 1993-03-08 | 1995-11-28 | Alliedsignal Inc. | Polymeric powder coating compositions comprising low molecular weight polyethylene polyols |
| US6228133B1 (en) * | 1998-05-01 | 2001-05-08 | 3M Innovative Properties Company | Abrasive articles having abrasive layer bond system derived from solid, dry-coated binder precursor particles having a fusible, radiation curable component |
| US6136398A (en) * | 1998-05-01 | 2000-10-24 | 3M Innovative Properties Company | Energy cured sealant composition |
| US6274643B1 (en) | 1998-05-01 | 2001-08-14 | 3M Innovative Properties Company | Epoxy/thermoplastic photocurable adhesive composition |
| US6057382A (en) * | 1998-05-01 | 2000-05-02 | 3M Innovative Properties Company | Epoxy/thermoplastic photocurable adhesive composition |
| US6077601A (en) | 1998-05-01 | 2000-06-20 | 3M Innovative Properties Company | Coated abrasive article |
| DE10306033A1 (en) * | 2003-02-13 | 2004-09-02 | Wacker Polymer Systems Gmbh & Co. Kg | Thermoset powder coatings containing extender resins |
| EP3263664B1 (en) | 2010-04-16 | 2020-11-04 | Swimc Llc | Coating compositions for packaging articles and methods of coating |
| CN107033730B (en) | 2011-02-07 | 2021-03-05 | 宣伟投资管理有限公司 | Coating compositions and methods for containers and other articles |
| BR112014030849B1 (en) * | 2012-06-13 | 2022-12-20 | Swimc Llc | METHOD FOR COATING AN ARTICLE |
| AU2013299578A1 (en) | 2012-08-09 | 2015-02-19 | Valspar Sourcing, Inc. | Compositions for containers and other articles and methods of using same |
| CN104540744B (en) | 2012-08-09 | 2017-08-25 | 威士伯采购公司 | Container coating system |
| EP3131965A4 (en) | 2014-04-14 | 2018-03-28 | Valspar Sourcing, Inc. | Methods of preparing compositions for containers and other articles and methods of using same |
| TWI614275B (en) | 2015-11-03 | 2018-02-11 | Valspar Sourcing Inc | Liquid epoxy resin composition for preparing a polymer |
| WO2020173547A1 (en) * | 2019-02-26 | 2020-09-03 | Wacker Chemie Ag | Cross-linkable, polymer-powder compositions re-dispersible in water |
| CN114316754B (en) * | 2021-12-24 | 2023-04-04 | 老虎表面技术新材料（清远）有限公司 | Antiskid powder coating composition and coating thereof |
Family Cites Families (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3578615A (en) * | 1968-04-08 | 1971-05-11 | Shell Oil Co | Epoxy resin coatings having improved cathodic disbonding resistance |
| US3542902A (en) * | 1968-06-28 | 1970-11-24 | Du Pont | Hydrolyzed ethylene/vinyl ester copolymer-epoxy resin blends |
| US3626026A (en) * | 1968-08-01 | 1971-12-07 | Hitachi Ltd | Hotmelt adhesive compositions |
| US3684778A (en) * | 1970-04-28 | 1972-08-15 | Du Pont | Polymers of ethylene, sulfur dioxide and ethylenic monomers |
| US3661828A (en) * | 1970-06-05 | 1972-05-09 | Ford Motor Co | Thermoset molding powders employing glycidyl methacrylate and diphenols |
| US3707583A (en) * | 1971-06-04 | 1972-12-26 | Minnesota Mining & Mfg | Adhesive |
| US3758633A (en) * | 1971-08-16 | 1973-09-11 | Ford Motor Co | Crosslinking agents and flow control agents powdered coating compositions of carboxy containing copolymers epoxy |
| JPS5033829B2 (en) * | 1971-09-29 | 1975-11-04 |
-
1975
- 1975-08-11 US US05/603,702 patent/US4009224A/en not_active Expired - Lifetime
-
1976
- 1976-07-22 CA CA257,525A patent/CA1082835A/en not_active Expired
- 1976-08-10 DE DE19762636394 patent/DE2636394A1/en active Granted
- 1976-08-10 JP JP9532676A patent/JPS5237963A/en active Granted
Also Published As
| Publication number | Publication date |
|---|---|
| JPS5237963A (en) | 1977-03-24 |
| JPS543895B2 (en) | 1979-02-28 |
| US4009224A (en) | 1977-02-22 |
| DE2636394C2 (en) | 1989-05-11 |
| DE2636394A1 (en) | 1977-02-24 |
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