CA1160386A - Thermoplastic elastomeric composition, product and method of manufacture - Google Patents
Thermoplastic elastomeric composition, product and method of manufactureInfo
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- CA1160386A CA1160386A CA000362748A CA362748A CA1160386A CA 1160386 A CA1160386 A CA 1160386A CA 000362748 A CA000362748 A CA 000362748A CA 362748 A CA362748 A CA 362748A CA 1160386 A CA1160386 A CA 1160386A
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Abstract
Abstract of the Disclosure An unvulcanized, moldable composition comprising 100 parts by weight of a thermoplastic elastomer, at least about 10 parts by weight of an extender oil per 100 parts by weight of the thermoplastic elastomer and at least about 20 parts by weight of a solid, hygroscopic filler, having greater than 1 percent by weight of absorbed water and capable of retaining a substantial portion of such water at temperatures of at least 100°C, per 100 parts by weight of the thermoplastic elastomer, the ratio of the oil to the hygroscopic filler being from about 0.3 to about 3. A method of flow molding by exposure to microwave energy while applying pressures below about 200 psi and a molded article of manufacture are also described.
Description
9 ~ 6 ~ 3 ~ 6 27980 THERMOPLASTIC E~ASTOMERI~ COMPOSITION, PRODUCT AND METHOD OF MANUFACTURE
Background of the Invention Rubbers and elastomers of either natural or synthetic origin generally require vulcanization in order to obtain useful elastomeric properties. Before vulcanization, rubbers possess tacky properties and low strength, which make them of little utility except as rubber cements. The optimum elastomeric properties are not attained unt:il the rubber has been subjected to a vulcanization treatment such as by means of heating with sulfur, sulfur compounds, peroxides, or other means. By contrast, thermoplastic elastomers in their "green" or unvulcanized state have been developed which can be utili~ed to make a wide variety of materials and articles having almost any 1~ desired properties. Consequently, such thermoplastic elastomers can be readily molded into useful articles J thereby saving the time and expense of vulcanization as well as retaining numerous properties which are not possessed by vulcanized rubbers or elastomels. A particularly useful group of such thermoplastic elastomers are conjugated diene/vinyl aromatic block copolymers.
It has been known in the past to extend thermoplastic elastomers with petroleum base oils such as naphthenic, aromatic and paraffinic oils in ordar to reduce costs and to improve the elastomeric properties of certain of the tharmoplastic elastomers. Further, it has also been known to add fillers or bodying agents to thermoplastic elastomers in order to reduce the cost of the material and to add bulk and strength to the same. While a vast number of fillers have been suggested in general terms for use in thermoplastic elasto-mers, there is, in fact, a limited number of such materials which have been successfully used and which are used almost universally. For example, fillers have generally been confined to silicas, carbon blacks, numerous varieties of china clay and whiting or calcium carbonate. However, it has been found that these so-called conventional fillars have a tendency to haraen thermoplastic elastomers and limit their uses in articles where flexibility flnd elasticity are desirable. This is particularly true when large amounts of such fillers are employed. Likewise, the use of excessive amounts of extender oils results in a product which has a tendency to bleed or exude a certain amount of the oil.
While the latter is a desirable characteristic in certain uses, in other instances it is highly undesirable.
There are also many methods of forming or molding thermoplastic elastomers such as injection or compression molding, vacuum forming and flow molding, and for applying a coating or sheet of thermoplastic elastomer to woven or non-woven textiles or other substrates, such as calendering or spread-ing the elastomer on the substrate as a hot melt. These known processes have one or more undesirable features such as requiring extreme pressures, being time-consuming, producing products of poor quality such as poor tear resistance in laminated objects and, in general, undue multiplication of tha number of steps required to produce the final product. Because of the reduced pressures required and the reduction in the processing steps necessary, flow molding is an attractive means of forming certain varieties of articles. In a flow mold-ing process, the moldable material in powder, pellet or particle form~ or in the form of a sheet is placed in a suitable mold, the mold is closed and the moldable composition heated to a temperature just sufficient to melt and cause flow of the moldable material into the interstices of the mold. Recently, a particularly attractive technique of flow molding has been suggested. In accordance with this procedure the usual flow molding process is carried out except that rather than using radiant heat to melt and cause flow of the moldable material, microwave energy is utilized. Heating with microwave energy has the obvious advantage of substantially shortening the processing time but, in addition, prevents the deleterious effects which often result from heating for extended periods of time.
It would, therefore, be desirable to provide a moldable thermoplastic elastomer composition which retains its property of good flexibility, to provide an article of manufacture having this desirable property and particularly to be able to utilize the above-described~ simplified microwave flow molding *echnique.
3~
It is therefore an object of the present invention to overcome the above-mentioned shortcomings of the prior art.
Another object of the present invention is to provide an improved unvulcanized, moldable composition, a simplified method of molding and an improved molded product.
Another object of the present invention is to provide an improved unvulcanized, moldable composi*ion including a conjugated diene/vinyl aromatic block copolymer.
Another and further object of the present invention is to provide an improved flow molding technique which utilizes microwave energy as a heat source.
~ et another object of the present invention is to provide an unvul-canized, molded axticle of manufacture having improved flexibility.
Another object of the present invention is to provide an improved unvulcanized, moldable thermoplastic elastomer composition containing a filler material and an extsnder oil, an improved technique for molding such composi-tion and an improved article of manufacture resulting therefrom.
A further ob~ject of the present invention is to provide an improved unvulcanized, modable thermoplastic elastomer composition containing large amounts of filler and extender oil, a simplified technique for molding such composition and an improved article of manufacture produced thereby.
The above and other objects and advantages of the present invention will be apparent from the following detailed description.
Summar~ of the Invention In accordance with the present invention, it has been found that an improved unvulcanized, moldable composition can be prepared by mixing 100 parts by weight of a thermoplastic elastomer, at least about 20 parts by weight of an extender oil per 100 parts by weight of the thermoplastic elastomer and at least about 10 parts by weight of a solid, hygroscopic filler, having greater than 1 percent by weight oE absorbed water and capable of retaining a sub-3i~
stantial portion of such water at temperatures of at least 100C, per 100 partsby weight of the thermoplastic elastomer, the ratio of the oil to the hygro-scopic filler being from about 0.3 to about 3. It has also been found in accordance wi-th the present invention that an improved unvulcanized, molded article of manufacture can be produced from the above composition, particularly a fabric substrate having said composition bonded thereto. It has further been found, in accordance with the present invention, that the above-mentioned unvulcanized, moldable composition can be simply and effectively molded by disposing the composition in a suitable mold and heating the composition by the application of mlcrowave energy thereto while applying a pressure below about 200 psi for a time just sufficient to mel-t the composition and cause flow of the sarne into the interstices of the mold.
The abo~e objects of the present invention and the nature of the present invention will be clear from the following description of the preferred embodiments.
Detailed Description of the Invention The thermoplastic elastomers useful in practicing the present in-vention are normally solid, block copolymers, characteristicly exhibiting high tensile strength and elongation in their natural condition, that is, in th~ir green or unvulcanized state. Particularly useful are linear block or radial teleblock copolymers. More specifically, useful elastomers are radial tele-block copolymers of butadiene/styrene. Such copolymers are described in more detail in U.S. Patents 3,823,109; 3,326,776 and 3,959,545. These polymers are prepared by methods well known in the art.
The butadiene/styrene copolymers, discussed above, generally contain about 50 to 90 weight percent butadiene and from 50 to about 10 weight percent of styrene; preferably, from about 50 to 70 weight percent butadiene and about S0 to about 30 weight percent styrene. Copolymers particularly useful in producing compositions in accordance with the present invention are those having from about 60 to about 70 weight percent butadiene. When less than about lO percent styrene is employed, the resulting copolymers do not possess the requisite green tensile strength. On the other hand, more than 50 weight percent of the styrene in the copolymer results in a compo3ition in which hardness is increased at the expense of elasticity. Useful copolymers will generally exhibit a weight average molecular weight in the range of from about 75,000 to about 500,000 but a range of about 100,000 to about 350,000 is preferable.
It is also within the scope of the present invention to add other polymers -to the thermoplastic elastomer in amounts up to about 150 parts by weight of the polymer per 100 parts by weight of the elastomer. Such addi-tional polymers are generally solid resinous polymers of a vinyl-substituted aromatlc compound, for example, styrene, alphamethyl styrene, etc., alone or copolymerized with a monomer such as acrylonitrile or a conjugated diene such as butadiene. Such homopolymers and copolymers generally have densities in the range of about 1.04 to about 1.10 gram/cc (ASTM D 792), a tensile strength in the range of from about 5,000 to about 12,000 psi (34.5-82.7 MPa), ASTM D-638, and a Shore A hardness ranging from about 35 to about 95 (ASTN D-2240) at about 23C.
The pr~viously mentioned thermoplastic elastomers may also have certain amounts of the extender oil incorporated therein during their manufac-ture. For example, the elastomers may have incorporated therein from 50 to 60 parts by weight of oil. Consequently, the amounts of added extender oil re-ferred to herein, and specifically in the examples, are amounts in addition to the amounts incorporated in the thermoplastic elastomer during its manufacture and the amounts of elastomer referred to include the weight of the elastomer including the oil added during elastomer preparation. Suitable extender oils include those well known in the art such as naphthenic, aromatic flnd paraffinic petroleum oils, particularly the naphthenic type.
In accordance with the present invention, the thermoplastic elastomer composition of the present invention may have added thereto at least ~:~33~
about 10 parts by weight of extender oil per 100 parts by weight of the thermoplastic elastomer. Preferred amounts of added extender oil include from about 70 to about 350 parts of oil per 100 parts of thermoplastic elastomer and ideally about 250 to about 300 parts of oil per 100 parts of thermoplastic elastomer.
It is frequently desirable to include other additives well known in the rubber art to the compositions of the present application. Stabilizers, antioxidants, conventional fillers, reinforcing agents, reinforcing resins, pigments, fragrances and the like are examples of some such additives. Speci-fic examples of useful antioxidants and stabilizers include 2-(2'-hydroxy-5'-methylphenyl) benzotriazole, nickel dibutyldithiocarbamate, zinc dibutyl di-thiocarbamate, tris(nonylphenyl) phosphite, 2,6-di-t-butyl-4-methylphenol and the like. Exemplary conventional fillers and pigments include silica, carbon ; black, titanium dioxide, iron oxide and the like. Polypropylene and poly-styrene are examples of thermoplastic resins which function as reinforcing agents. A butadiene/acrylonitrile elastomer is an example of an elastomer which functions as a processing aid.
In addition to the above conventional ingredients/ it has been found, in accordance with the prèsent invention, that an unvulcanized, moldable com-position of a thermoplastic elastomer can be produced by adding thereto a solid, hygroscopic filler, having greater than 1 percent by weight, and prefer-ably greater than 4.0 percent by weight, of absorbed water and capable of retaining a substantial portion of such water at temperatures of at least 100C, such as, bentonite clay, particularly the Western type, wood flour, ground cork, etc., in addition to the usual amounts of the more conventional fillers and pigments. The hygroscopic filier may be utilized in amounts in excess of about 45 parts by weight of fillex per 100 parts of thermoplastic elastomer (phr). These amounts do not include the usual amounts of conven-tional fillers and pigments which can be used. Preferably, the hygroscopic filler is utilized in amounts between about 350 and about 500 parts by weight ~..~3~3~
of filler per 100 parts by weight of thermoplastic elastomer and ideally about 400 parts filler per 100 parts thermoplastic elastomer. It has also been found, in accordance with the present invention, that superior products can be produced by employing a particular range of extender oil/hygroscopic filler.
Specifically, the desired weight ratios of oil to hygroscopic filler are 0.3 to 3, preferably 0.5 to 1.0 and ideally about 0.75.
The thermoplastic elastomer compositions of the present invention may be prepared by any means well known in the art for combining such ingredients, such as solution blending, milling~ internal batch mixing, or continuous extrusion of a solid form of elastomer and the other ingredients.
rapid and convenient method o~ preparation comprises heating a mixture of the components to a temperature of about 120C to about 205C, wh:ile separate specific embodiments preferably involve stirring a mixture of the components at about 160C to about 205C, preferably about 175C to about 205C or by heating the mixture without stirring in a temperature range of about 125C to about 200C, preferably about 125C to about 165C. Preferably, the hygroscopic filler is capable of retaining a substantial portion of its absorbed water at temperatures above the melt temperature of the composition (usually about 160C) and up to the highest temperature utilized in the preparation of the composition prior to molding.
One method of preparing a composition comprising a conjugated di~.ne/vinyl aromatic block copolymer and extender oil involves placing a mixture of the copolymer and extender oil in suitable container such as a flat metal pan and heating said mixture, such as in an oven, without agitation at a temperature which normally falls within the range corresponding to about the melting point of the elastomer, about 120C, up to about the flash point of the ! oil, about 200C. Normally and preferably, heating is conducted within the range of about 125C to about 165C. The composition can be fo:rmed of the mixture within a time of several seconds to several hours but the mixture is normally maintained at thls temperature Eor abou-c 15 minutes to several hours.
~ ~3 3~36 The -time required is dependent upon such things as the type of the elastomer and oil employed, the temperature used and the physical size of the particles of elastomer to be used in preparation of the composition. ~urthermore, the time required to make a homogeneous mixture can normally be reduced by physically mixing the rubber and -the oil prior to the heating step.
Additional additives and formula-tions can be added to the elastomer-oil blend prior to or during the heating step. After the heating step, the composition is normally cooled prior to use in fabricating articles.
The composition can be further trea~ed if desired or required in any conventional mixer such as a Banbury~ (~mhart Nachinery Group, Ansonia, Conn.) mixer or roll mill, particularly if small amounts of undissolved elastomer remain aE~er the oven heating step or if it is desirable -to add other ingredients prior to or during the heating step and such have not been uniformly distributed. The additional treatment, if desired, is normally co~ducted within the temperature range of about 75C to about ~25C, preferably maintaining the composition below its melting point for a few minutes up to several hours, preferably 3 to 15 minutes. A par-ticularly useful technique is to add the hygrosGopic filler in the beginning of the mixing cycle in order to take maximum advantage of heating time and to prevent surface bleeding and overheating when forming the molded articles.
The resultant composition may be in the form of extruded pellets, ; cut dices, preferably as small as possible since smaller pellets provide short heating times and better flow when utilized in flow molding. Ground pellets may also be utilized. Where large area objects are to be made, such as in ~he manufacture of mats, the composition may be provided in sheet form in order to shorten the heating time and effect better flow during the molding operation.
It has been found, unexpectedly, in accordance with the present i~-vention that by utilizing a solid hygroscopic filler, as previously discussed, reduced time for incorporating extender oil, ease of incorporation and ex-tremely good dispersion are attained. On the other hand, it was found ~hatwhen usirlg conventional iillers, such as calcium carbonate (whiting~ or china P~ 9 ?3~
clay, particularly at high levels, extremely long mixing times were required and, more importantly, the resultant products were very dry, brittle and completely unusable. Talc, par-ticularly at high loadings, also resulted in unexpectably long mixing times and may produce unaccep-tably stiff and boardy products. By comparisonJ products formed from the composition containing the hygroscopic fillers exhibited very good rubberiness and other physical properties.
It has also been found, in accordance with the present invention, that the composition containing hygroscopic fillers responded much better to microwave energy heating than mate,rials filled with calcium carbonate, Dixie clays, talc, etc, The mixing difficulties with the china-type clay included excessive stickiness in the mixer which made it impossible to conventionally dump the mixed product.
It has also been found, in accordance with the present invention, that mixtures in accordance with the present invention respond unexpectedly to heating by microwave energy. It is known that the thermoplastic elastomers, in accordance with the present invention, do not~ in and of themselves, respond well to heating by microwave radiation. However, it has been discovered in accordance with the present invention that the response of the thermoplastic elastomers to microwave radiation is significantly improved by the addition of the hygroscopic fillers. While the present invention is not intended to be limited by any theory, it is believed that the presence and retention of signi-ficant amounts of absorbed water by the hygroscopic filler is responsible for such enhancement of the response of the composition to microwave radiation.
Consaquently, the hygroscopic filler should be capable of retaining a signifi-cant amount of its abosrbed water at temperatures above the boiling point of water, preferably above the melt temperature o~ the composition (usually about 160C) and up to the temperature utilized in the preparation of the composition for molding and ideally up to the highest -temperature reached in the molding operation (generally between about 280 and abo~lt ~S0~ [138-~L~3~36 268C~). If-the absorbed water of the hygroscopic filler is driven off during preparation of the mixture for flow molding, the improved response to microwave radiation does not occur, and the advantages during flow molding and of the resultant product, set forth hereinl are not attained. In any event, tests have shown that if the hygroscopic fillers are dried before compounding, the receptivity to microwave radiation is significantly reduced. In addition, if the water is driven off during flow molding surface pits and/or porosity in the product result from the evolution of steam. Hence, the compositions of the present invention containing the hygroscopic fillers, as defined, are not as sensitive to overheating as iormulations containing nonhygroscopic fillers With significant amounts of absorbed water which will not be retained during flow molding. The above-mentioned ability to enhance the response to microwave radiation is particularly noticeable at high concentrations ~f hygroscopic filler.
; Undesirable evolution of steam can also be controlled by incorporating in the mixture appropriate amounts (about 5 to about 25 parts by weight and preferably 20 parts by weight) of a waterbinding agent like calcium oxide, preferably in the form of an oil dispersion.
By definition, the microwave region1is that portion of the electro-magnetic spectrum lying between the far infrared and the conventional radio frequency portion. While the microwave region is not bounded by definition it is commonly regarded as extending from 300,000 megacycles to 1,000 megacycles (l mm to 30 cm in wavelength). In most areas of the world certain frequencies have been assigned for industrial uses of microwave energy. For example~ in *he Unlted States the assigned frequencies are 915 and 2,450 megahertz (~Hz), in Europe assigned irequencies are 896 and 2,450 megahertz and in Japan 40 to 50 megahertz. When a material capable of absorbing microwave energy, rather \
than reflecting the same or being transparent thereto, is tr~ated with micro-wave energy, heat i.s produced as a result of the absorption of the microwaves.
3~36 While, as previously indicated, the compositions of this invention respond well to microwave energy, it is preferred that a polar composition be added as a sensitizer to ~urther enhance the response to microwave energy. Not all polar compounds have been found effective in enhancing the microwave energy response of the compos:itions but there are a large number which have been found so effective. For example, a material selected from among simple and polymeric alkylene glycols and their mono- and dialkyl ethers, ethanol amines and iso-propanol amines and their hydrocarbyl-substituted derivatives and mixtures thereof have been found particularly useful. Exemplary compounds include ethylene glycol, 1,2-propylene glycol, 1,3-butylene glycol, 1,4-butylene glycol, 1,6-hexylene glycol, diethylene glycol, triethylene glycol, dipropylene glycol, thiodiethylene glycol, etc., polyethylene glycols having average molecular weights ranging from about 200 to 6,000 (commercially available under the trademark "Carbowax" from Union Carbide Corp., ~ew York, N.Y.) polypropylene glycols having average molecular weights from about 400 to about 2,000; mixed poly~ethylene~-poly(propylene) glycols having average molecular weights up to about 6,000 and containing from about 30 to about 90 weight percent e-thylene oxide; the monomethyl, monoethyl, and monobutyl ethers o ethylene glycol, propylene glycol and diethylene glycol; -the monomethyl and monoethyl ethers of triethylene glycols; the dimethyl and diethyl ethers o~
diethylene glycol, dipropylene glycol and trimethylene glycol; the alkanolamines and substituted alkanolamines based on ethanol and isopropanol such as mono-, di- and -tri-ethanol amine, ~ono-, di- and triisopropylamine, methylethanolamine, dibutylethanolamine, phenyldiethanolamine, di~2-ethylhexyl)e~hanolamine, dimethylisopropanolamine, dibutylisopropanolamine, and the like; and mixtures thereof. Other polar compounds such as acrylonitrile/butadiene copolymers, acrylonitrile/butadiene blends with homopolymers o~ polyvinyl chloride and styrene/acrylonitrile copolymers are also e~fective. Other materials suitable as polarizing agents include glyceryl diacetate; di(2~hydroxyeth~1) dimethylhydantoin; ionomer resins, particularly ~ 12 3~6 with other polarizing agents and polyphenyleneoxide-polystyrene blends.
Presently preferred compounds include diethylene glycol and triethenolamine and particularly mixtures thereof and mixtures thereof with polyethylene glycols.
The polar agent will generally be utilized in a range of from about 0.5 to about 20 parts by weight per 100 parts by weight of thermoplastic elastomer (phr3 and preferably about 0.75 to about 10 parts by weight per 100 parts by weight of thermoplastic elastomer.
While it has been observed that ~ome pitting and/or porosity results when utilizing polar sensitizers in the present process, this problem can be solved by avoiding overheating ~unnece.ssarily long periods of exposure to microwave energy), reducing the amount of polar sensi-tizer employed and/or adding a waterbinding agent llke calcium oxide, as previously indicated.
It has also been found, in accordance with the present invention, that the addition of ethylene/vinyl acetata copolymer provides an unexpectedly increased response to microwave energy. Specifically, it has been found that by adding about 25 to about 35 parts by weight, preferably about 30 parts by weighe~ of such polymer to 100 parts by weight of thermoplastic elastomer the time required for microwave heating can be reduced by about one-half.
One of the distinct advantages of flow molding, utilizing microwave energy as a heating source, is the fact that relatively inexpensive molds can be utllized. For example, molds made of cast liquid silicone compounds may be utilized due to the fact thet heating is rapid and pressures below about 200 psi can be utilized.
The process of flow molding in accordance with the present invention is carried out simply by disposing the thermoplastic elastomer moldable com-position in a suitable mold in pellet form, ground pellet form or sheet form, applying a release sheet such as Teflon on the top of the composition, closing the mold and exposing the closed mold to microwave ensrgy while applying a prsssure up to about 200 psi. ~ suitable microwave unit and one which has been 3~
utilized hereinafter in the specific examples is a KN unit, Model J9 manufac-tured by Compo Industries, Inc., Waltham, Mass. When a sheet of the moldable thermoplastic composition is to be bonded to a woven or non-woven fabric, for example to form a carpeting mat, this is accomplished by placing the moldable composition in the bottom of the mold as previously mentioned, placing the fabric, cut to size, on top of the moldable composition, placing a release sheet on top of the fabric, closing the mold and subjecting the same to micro-wave energy and pressure as previously described.
The following specific examples illustrate the improved compositions, techniques of molding and articles of manufacture produced in accord~nce with the present invention.
EXAMPLE I
Two tests were conducted utilizing two different composltions com-prising butadiene/styrene radial teleblock copolymers. A 6 inch by 6 inch sheet of the thermoplastic elastomer composition having a thickness of Q.170 inch was placed in a suitable mold. A carpeting of polyester was cut to the same lateral dimensions and placed on top of the sheet of thermoplastic elas-tomer. A release sheet was placed on top of the carpet and the mold closed.
The specimen was then subjected to high frequency microwave energy from a Compo Industries, Inc. Model J microwave generator having a 10 kilowatt output. The microwave generator was set at 80 percent power. The following table ssts forth the overall composition of the polymeric elastomer composition, the heating times necessary to attain various results and the physical appearance of the resultant backed carpeting.
Table I
1~ 2*
Butadiene/Styrene Radial Teleblock (70/30 Bd/St) 100 --Butadiene/Styrene Radial Teleblock (60/40 Bd/St) -- 100 Polystyrene 70 35 Alphamethylstyrene Polymer -- 35 Silica 30 30 Naphthenic Oil 300 250 3Ei6 Bentonite Clay (Western Type) 400 350 Zinc Stearate 0.~0 0.80 Antioxidant( ~ 0.70 0.70 Ethylene/Vinyl Acstate Copolymer(2) 30 --Ethylene/Vinyl Acetate Copolymer(3) -- 30 Iron Oxide 2 2 Furnace Black, ASTM N-550 0.5 0.5 Polyethylene Glycol, Molecular Weight About 540 3 3 Triethanolamine 6 6 943.00843.00 Good bond, but not rubber tear 4 Sec. 6 Sec.
Perfect bond with rubber tear 5-6 Sec. 7-lO Sec.
Too much penetration into carpet 8 Sec. 12 Sec.
*Ingredients are in parts by weight per 100 parts by weight of the thermoplastic elastomer (phr).
(l) Argus Chemica} Corp., Brooklyn, N.Y., Mark(R) 1589B.
Background of the Invention Rubbers and elastomers of either natural or synthetic origin generally require vulcanization in order to obtain useful elastomeric properties. Before vulcanization, rubbers possess tacky properties and low strength, which make them of little utility except as rubber cements. The optimum elastomeric properties are not attained unt:il the rubber has been subjected to a vulcanization treatment such as by means of heating with sulfur, sulfur compounds, peroxides, or other means. By contrast, thermoplastic elastomers in their "green" or unvulcanized state have been developed which can be utili~ed to make a wide variety of materials and articles having almost any 1~ desired properties. Consequently, such thermoplastic elastomers can be readily molded into useful articles J thereby saving the time and expense of vulcanization as well as retaining numerous properties which are not possessed by vulcanized rubbers or elastomels. A particularly useful group of such thermoplastic elastomers are conjugated diene/vinyl aromatic block copolymers.
It has been known in the past to extend thermoplastic elastomers with petroleum base oils such as naphthenic, aromatic and paraffinic oils in ordar to reduce costs and to improve the elastomeric properties of certain of the tharmoplastic elastomers. Further, it has also been known to add fillers or bodying agents to thermoplastic elastomers in order to reduce the cost of the material and to add bulk and strength to the same. While a vast number of fillers have been suggested in general terms for use in thermoplastic elasto-mers, there is, in fact, a limited number of such materials which have been successfully used and which are used almost universally. For example, fillers have generally been confined to silicas, carbon blacks, numerous varieties of china clay and whiting or calcium carbonate. However, it has been found that these so-called conventional fillars have a tendency to haraen thermoplastic elastomers and limit their uses in articles where flexibility flnd elasticity are desirable. This is particularly true when large amounts of such fillers are employed. Likewise, the use of excessive amounts of extender oils results in a product which has a tendency to bleed or exude a certain amount of the oil.
While the latter is a desirable characteristic in certain uses, in other instances it is highly undesirable.
There are also many methods of forming or molding thermoplastic elastomers such as injection or compression molding, vacuum forming and flow molding, and for applying a coating or sheet of thermoplastic elastomer to woven or non-woven textiles or other substrates, such as calendering or spread-ing the elastomer on the substrate as a hot melt. These known processes have one or more undesirable features such as requiring extreme pressures, being time-consuming, producing products of poor quality such as poor tear resistance in laminated objects and, in general, undue multiplication of tha number of steps required to produce the final product. Because of the reduced pressures required and the reduction in the processing steps necessary, flow molding is an attractive means of forming certain varieties of articles. In a flow mold-ing process, the moldable material in powder, pellet or particle form~ or in the form of a sheet is placed in a suitable mold, the mold is closed and the moldable composition heated to a temperature just sufficient to melt and cause flow of the moldable material into the interstices of the mold. Recently, a particularly attractive technique of flow molding has been suggested. In accordance with this procedure the usual flow molding process is carried out except that rather than using radiant heat to melt and cause flow of the moldable material, microwave energy is utilized. Heating with microwave energy has the obvious advantage of substantially shortening the processing time but, in addition, prevents the deleterious effects which often result from heating for extended periods of time.
It would, therefore, be desirable to provide a moldable thermoplastic elastomer composition which retains its property of good flexibility, to provide an article of manufacture having this desirable property and particularly to be able to utilize the above-described~ simplified microwave flow molding *echnique.
3~
It is therefore an object of the present invention to overcome the above-mentioned shortcomings of the prior art.
Another object of the present invention is to provide an improved unvulcanized, moldable composition, a simplified method of molding and an improved molded product.
Another object of the present invention is to provide an improved unvulcanized, moldable composi*ion including a conjugated diene/vinyl aromatic block copolymer.
Another and further object of the present invention is to provide an improved flow molding technique which utilizes microwave energy as a heat source.
~ et another object of the present invention is to provide an unvul-canized, molded axticle of manufacture having improved flexibility.
Another object of the present invention is to provide an improved unvulcanized, moldable thermoplastic elastomer composition containing a filler material and an extsnder oil, an improved technique for molding such composi-tion and an improved article of manufacture resulting therefrom.
A further ob~ject of the present invention is to provide an improved unvulcanized, modable thermoplastic elastomer composition containing large amounts of filler and extender oil, a simplified technique for molding such composition and an improved article of manufacture produced thereby.
The above and other objects and advantages of the present invention will be apparent from the following detailed description.
Summar~ of the Invention In accordance with the present invention, it has been found that an improved unvulcanized, moldable composition can be prepared by mixing 100 parts by weight of a thermoplastic elastomer, at least about 20 parts by weight of an extender oil per 100 parts by weight of the thermoplastic elastomer and at least about 10 parts by weight of a solid, hygroscopic filler, having greater than 1 percent by weight oE absorbed water and capable of retaining a sub-3i~
stantial portion of such water at temperatures of at least 100C, per 100 partsby weight of the thermoplastic elastomer, the ratio of the oil to the hygro-scopic filler being from about 0.3 to about 3. It has also been found in accordance wi-th the present invention that an improved unvulcanized, molded article of manufacture can be produced from the above composition, particularly a fabric substrate having said composition bonded thereto. It has further been found, in accordance with the present invention, that the above-mentioned unvulcanized, moldable composition can be simply and effectively molded by disposing the composition in a suitable mold and heating the composition by the application of mlcrowave energy thereto while applying a pressure below about 200 psi for a time just sufficient to mel-t the composition and cause flow of the sarne into the interstices of the mold.
The abo~e objects of the present invention and the nature of the present invention will be clear from the following description of the preferred embodiments.
Detailed Description of the Invention The thermoplastic elastomers useful in practicing the present in-vention are normally solid, block copolymers, characteristicly exhibiting high tensile strength and elongation in their natural condition, that is, in th~ir green or unvulcanized state. Particularly useful are linear block or radial teleblock copolymers. More specifically, useful elastomers are radial tele-block copolymers of butadiene/styrene. Such copolymers are described in more detail in U.S. Patents 3,823,109; 3,326,776 and 3,959,545. These polymers are prepared by methods well known in the art.
The butadiene/styrene copolymers, discussed above, generally contain about 50 to 90 weight percent butadiene and from 50 to about 10 weight percent of styrene; preferably, from about 50 to 70 weight percent butadiene and about S0 to about 30 weight percent styrene. Copolymers particularly useful in producing compositions in accordance with the present invention are those having from about 60 to about 70 weight percent butadiene. When less than about lO percent styrene is employed, the resulting copolymers do not possess the requisite green tensile strength. On the other hand, more than 50 weight percent of the styrene in the copolymer results in a compo3ition in which hardness is increased at the expense of elasticity. Useful copolymers will generally exhibit a weight average molecular weight in the range of from about 75,000 to about 500,000 but a range of about 100,000 to about 350,000 is preferable.
It is also within the scope of the present invention to add other polymers -to the thermoplastic elastomer in amounts up to about 150 parts by weight of the polymer per 100 parts by weight of the elastomer. Such addi-tional polymers are generally solid resinous polymers of a vinyl-substituted aromatlc compound, for example, styrene, alphamethyl styrene, etc., alone or copolymerized with a monomer such as acrylonitrile or a conjugated diene such as butadiene. Such homopolymers and copolymers generally have densities in the range of about 1.04 to about 1.10 gram/cc (ASTM D 792), a tensile strength in the range of from about 5,000 to about 12,000 psi (34.5-82.7 MPa), ASTM D-638, and a Shore A hardness ranging from about 35 to about 95 (ASTN D-2240) at about 23C.
The pr~viously mentioned thermoplastic elastomers may also have certain amounts of the extender oil incorporated therein during their manufac-ture. For example, the elastomers may have incorporated therein from 50 to 60 parts by weight of oil. Consequently, the amounts of added extender oil re-ferred to herein, and specifically in the examples, are amounts in addition to the amounts incorporated in the thermoplastic elastomer during its manufacture and the amounts of elastomer referred to include the weight of the elastomer including the oil added during elastomer preparation. Suitable extender oils include those well known in the art such as naphthenic, aromatic flnd paraffinic petroleum oils, particularly the naphthenic type.
In accordance with the present invention, the thermoplastic elastomer composition of the present invention may have added thereto at least ~:~33~
about 10 parts by weight of extender oil per 100 parts by weight of the thermoplastic elastomer. Preferred amounts of added extender oil include from about 70 to about 350 parts of oil per 100 parts of thermoplastic elastomer and ideally about 250 to about 300 parts of oil per 100 parts of thermoplastic elastomer.
It is frequently desirable to include other additives well known in the rubber art to the compositions of the present application. Stabilizers, antioxidants, conventional fillers, reinforcing agents, reinforcing resins, pigments, fragrances and the like are examples of some such additives. Speci-fic examples of useful antioxidants and stabilizers include 2-(2'-hydroxy-5'-methylphenyl) benzotriazole, nickel dibutyldithiocarbamate, zinc dibutyl di-thiocarbamate, tris(nonylphenyl) phosphite, 2,6-di-t-butyl-4-methylphenol and the like. Exemplary conventional fillers and pigments include silica, carbon ; black, titanium dioxide, iron oxide and the like. Polypropylene and poly-styrene are examples of thermoplastic resins which function as reinforcing agents. A butadiene/acrylonitrile elastomer is an example of an elastomer which functions as a processing aid.
In addition to the above conventional ingredients/ it has been found, in accordance with the prèsent invention, that an unvulcanized, moldable com-position of a thermoplastic elastomer can be produced by adding thereto a solid, hygroscopic filler, having greater than 1 percent by weight, and prefer-ably greater than 4.0 percent by weight, of absorbed water and capable of retaining a substantial portion of such water at temperatures of at least 100C, such as, bentonite clay, particularly the Western type, wood flour, ground cork, etc., in addition to the usual amounts of the more conventional fillers and pigments. The hygroscopic filier may be utilized in amounts in excess of about 45 parts by weight of fillex per 100 parts of thermoplastic elastomer (phr). These amounts do not include the usual amounts of conven-tional fillers and pigments which can be used. Preferably, the hygroscopic filler is utilized in amounts between about 350 and about 500 parts by weight ~..~3~3~
of filler per 100 parts by weight of thermoplastic elastomer and ideally about 400 parts filler per 100 parts thermoplastic elastomer. It has also been found, in accordance with the present invention, that superior products can be produced by employing a particular range of extender oil/hygroscopic filler.
Specifically, the desired weight ratios of oil to hygroscopic filler are 0.3 to 3, preferably 0.5 to 1.0 and ideally about 0.75.
The thermoplastic elastomer compositions of the present invention may be prepared by any means well known in the art for combining such ingredients, such as solution blending, milling~ internal batch mixing, or continuous extrusion of a solid form of elastomer and the other ingredients.
rapid and convenient method o~ preparation comprises heating a mixture of the components to a temperature of about 120C to about 205C, wh:ile separate specific embodiments preferably involve stirring a mixture of the components at about 160C to about 205C, preferably about 175C to about 205C or by heating the mixture without stirring in a temperature range of about 125C to about 200C, preferably about 125C to about 165C. Preferably, the hygroscopic filler is capable of retaining a substantial portion of its absorbed water at temperatures above the melt temperature of the composition (usually about 160C) and up to the highest temperature utilized in the preparation of the composition prior to molding.
One method of preparing a composition comprising a conjugated di~.ne/vinyl aromatic block copolymer and extender oil involves placing a mixture of the copolymer and extender oil in suitable container such as a flat metal pan and heating said mixture, such as in an oven, without agitation at a temperature which normally falls within the range corresponding to about the melting point of the elastomer, about 120C, up to about the flash point of the ! oil, about 200C. Normally and preferably, heating is conducted within the range of about 125C to about 165C. The composition can be fo:rmed of the mixture within a time of several seconds to several hours but the mixture is normally maintained at thls temperature Eor abou-c 15 minutes to several hours.
~ ~3 3~36 The -time required is dependent upon such things as the type of the elastomer and oil employed, the temperature used and the physical size of the particles of elastomer to be used in preparation of the composition. ~urthermore, the time required to make a homogeneous mixture can normally be reduced by physically mixing the rubber and -the oil prior to the heating step.
Additional additives and formula-tions can be added to the elastomer-oil blend prior to or during the heating step. After the heating step, the composition is normally cooled prior to use in fabricating articles.
The composition can be further trea~ed if desired or required in any conventional mixer such as a Banbury~ (~mhart Nachinery Group, Ansonia, Conn.) mixer or roll mill, particularly if small amounts of undissolved elastomer remain aE~er the oven heating step or if it is desirable -to add other ingredients prior to or during the heating step and such have not been uniformly distributed. The additional treatment, if desired, is normally co~ducted within the temperature range of about 75C to about ~25C, preferably maintaining the composition below its melting point for a few minutes up to several hours, preferably 3 to 15 minutes. A par-ticularly useful technique is to add the hygrosGopic filler in the beginning of the mixing cycle in order to take maximum advantage of heating time and to prevent surface bleeding and overheating when forming the molded articles.
The resultant composition may be in the form of extruded pellets, ; cut dices, preferably as small as possible since smaller pellets provide short heating times and better flow when utilized in flow molding. Ground pellets may also be utilized. Where large area objects are to be made, such as in ~he manufacture of mats, the composition may be provided in sheet form in order to shorten the heating time and effect better flow during the molding operation.
It has been found, unexpectedly, in accordance with the present i~-vention that by utilizing a solid hygroscopic filler, as previously discussed, reduced time for incorporating extender oil, ease of incorporation and ex-tremely good dispersion are attained. On the other hand, it was found ~hatwhen usirlg conventional iillers, such as calcium carbonate (whiting~ or china P~ 9 ?3~
clay, particularly at high levels, extremely long mixing times were required and, more importantly, the resultant products were very dry, brittle and completely unusable. Talc, par-ticularly at high loadings, also resulted in unexpectably long mixing times and may produce unaccep-tably stiff and boardy products. By comparisonJ products formed from the composition containing the hygroscopic fillers exhibited very good rubberiness and other physical properties.
It has also been found, in accordance with the present invention, that the composition containing hygroscopic fillers responded much better to microwave energy heating than mate,rials filled with calcium carbonate, Dixie clays, talc, etc, The mixing difficulties with the china-type clay included excessive stickiness in the mixer which made it impossible to conventionally dump the mixed product.
It has also been found, in accordance with the present invention, that mixtures in accordance with the present invention respond unexpectedly to heating by microwave energy. It is known that the thermoplastic elastomers, in accordance with the present invention, do not~ in and of themselves, respond well to heating by microwave radiation. However, it has been discovered in accordance with the present invention that the response of the thermoplastic elastomers to microwave radiation is significantly improved by the addition of the hygroscopic fillers. While the present invention is not intended to be limited by any theory, it is believed that the presence and retention of signi-ficant amounts of absorbed water by the hygroscopic filler is responsible for such enhancement of the response of the composition to microwave radiation.
Consaquently, the hygroscopic filler should be capable of retaining a signifi-cant amount of its abosrbed water at temperatures above the boiling point of water, preferably above the melt temperature o~ the composition (usually about 160C) and up to the temperature utilized in the preparation of the composition for molding and ideally up to the highest -temperature reached in the molding operation (generally between about 280 and abo~lt ~S0~ [138-~L~3~36 268C~). If-the absorbed water of the hygroscopic filler is driven off during preparation of the mixture for flow molding, the improved response to microwave radiation does not occur, and the advantages during flow molding and of the resultant product, set forth hereinl are not attained. In any event, tests have shown that if the hygroscopic fillers are dried before compounding, the receptivity to microwave radiation is significantly reduced. In addition, if the water is driven off during flow molding surface pits and/or porosity in the product result from the evolution of steam. Hence, the compositions of the present invention containing the hygroscopic fillers, as defined, are not as sensitive to overheating as iormulations containing nonhygroscopic fillers With significant amounts of absorbed water which will not be retained during flow molding. The above-mentioned ability to enhance the response to microwave radiation is particularly noticeable at high concentrations ~f hygroscopic filler.
; Undesirable evolution of steam can also be controlled by incorporating in the mixture appropriate amounts (about 5 to about 25 parts by weight and preferably 20 parts by weight) of a waterbinding agent like calcium oxide, preferably in the form of an oil dispersion.
By definition, the microwave region1is that portion of the electro-magnetic spectrum lying between the far infrared and the conventional radio frequency portion. While the microwave region is not bounded by definition it is commonly regarded as extending from 300,000 megacycles to 1,000 megacycles (l mm to 30 cm in wavelength). In most areas of the world certain frequencies have been assigned for industrial uses of microwave energy. For example~ in *he Unlted States the assigned frequencies are 915 and 2,450 megahertz (~Hz), in Europe assigned irequencies are 896 and 2,450 megahertz and in Japan 40 to 50 megahertz. When a material capable of absorbing microwave energy, rather \
than reflecting the same or being transparent thereto, is tr~ated with micro-wave energy, heat i.s produced as a result of the absorption of the microwaves.
3~36 While, as previously indicated, the compositions of this invention respond well to microwave energy, it is preferred that a polar composition be added as a sensitizer to ~urther enhance the response to microwave energy. Not all polar compounds have been found effective in enhancing the microwave energy response of the compos:itions but there are a large number which have been found so effective. For example, a material selected from among simple and polymeric alkylene glycols and their mono- and dialkyl ethers, ethanol amines and iso-propanol amines and their hydrocarbyl-substituted derivatives and mixtures thereof have been found particularly useful. Exemplary compounds include ethylene glycol, 1,2-propylene glycol, 1,3-butylene glycol, 1,4-butylene glycol, 1,6-hexylene glycol, diethylene glycol, triethylene glycol, dipropylene glycol, thiodiethylene glycol, etc., polyethylene glycols having average molecular weights ranging from about 200 to 6,000 (commercially available under the trademark "Carbowax" from Union Carbide Corp., ~ew York, N.Y.) polypropylene glycols having average molecular weights from about 400 to about 2,000; mixed poly~ethylene~-poly(propylene) glycols having average molecular weights up to about 6,000 and containing from about 30 to about 90 weight percent e-thylene oxide; the monomethyl, monoethyl, and monobutyl ethers o ethylene glycol, propylene glycol and diethylene glycol; -the monomethyl and monoethyl ethers of triethylene glycols; the dimethyl and diethyl ethers o~
diethylene glycol, dipropylene glycol and trimethylene glycol; the alkanolamines and substituted alkanolamines based on ethanol and isopropanol such as mono-, di- and -tri-ethanol amine, ~ono-, di- and triisopropylamine, methylethanolamine, dibutylethanolamine, phenyldiethanolamine, di~2-ethylhexyl)e~hanolamine, dimethylisopropanolamine, dibutylisopropanolamine, and the like; and mixtures thereof. Other polar compounds such as acrylonitrile/butadiene copolymers, acrylonitrile/butadiene blends with homopolymers o~ polyvinyl chloride and styrene/acrylonitrile copolymers are also e~fective. Other materials suitable as polarizing agents include glyceryl diacetate; di(2~hydroxyeth~1) dimethylhydantoin; ionomer resins, particularly ~ 12 3~6 with other polarizing agents and polyphenyleneoxide-polystyrene blends.
Presently preferred compounds include diethylene glycol and triethenolamine and particularly mixtures thereof and mixtures thereof with polyethylene glycols.
The polar agent will generally be utilized in a range of from about 0.5 to about 20 parts by weight per 100 parts by weight of thermoplastic elastomer (phr3 and preferably about 0.75 to about 10 parts by weight per 100 parts by weight of thermoplastic elastomer.
While it has been observed that ~ome pitting and/or porosity results when utilizing polar sensitizers in the present process, this problem can be solved by avoiding overheating ~unnece.ssarily long periods of exposure to microwave energy), reducing the amount of polar sensi-tizer employed and/or adding a waterbinding agent llke calcium oxide, as previously indicated.
It has also been found, in accordance with the present invention, that the addition of ethylene/vinyl acetata copolymer provides an unexpectedly increased response to microwave energy. Specifically, it has been found that by adding about 25 to about 35 parts by weight, preferably about 30 parts by weighe~ of such polymer to 100 parts by weight of thermoplastic elastomer the time required for microwave heating can be reduced by about one-half.
One of the distinct advantages of flow molding, utilizing microwave energy as a heating source, is the fact that relatively inexpensive molds can be utllized. For example, molds made of cast liquid silicone compounds may be utilized due to the fact thet heating is rapid and pressures below about 200 psi can be utilized.
The process of flow molding in accordance with the present invention is carried out simply by disposing the thermoplastic elastomer moldable com-position in a suitable mold in pellet form, ground pellet form or sheet form, applying a release sheet such as Teflon on the top of the composition, closing the mold and exposing the closed mold to microwave ensrgy while applying a prsssure up to about 200 psi. ~ suitable microwave unit and one which has been 3~
utilized hereinafter in the specific examples is a KN unit, Model J9 manufac-tured by Compo Industries, Inc., Waltham, Mass. When a sheet of the moldable thermoplastic composition is to be bonded to a woven or non-woven fabric, for example to form a carpeting mat, this is accomplished by placing the moldable composition in the bottom of the mold as previously mentioned, placing the fabric, cut to size, on top of the moldable composition, placing a release sheet on top of the fabric, closing the mold and subjecting the same to micro-wave energy and pressure as previously described.
The following specific examples illustrate the improved compositions, techniques of molding and articles of manufacture produced in accord~nce with the present invention.
EXAMPLE I
Two tests were conducted utilizing two different composltions com-prising butadiene/styrene radial teleblock copolymers. A 6 inch by 6 inch sheet of the thermoplastic elastomer composition having a thickness of Q.170 inch was placed in a suitable mold. A carpeting of polyester was cut to the same lateral dimensions and placed on top of the sheet of thermoplastic elas-tomer. A release sheet was placed on top of the carpet and the mold closed.
The specimen was then subjected to high frequency microwave energy from a Compo Industries, Inc. Model J microwave generator having a 10 kilowatt output. The microwave generator was set at 80 percent power. The following table ssts forth the overall composition of the polymeric elastomer composition, the heating times necessary to attain various results and the physical appearance of the resultant backed carpeting.
Table I
1~ 2*
Butadiene/Styrene Radial Teleblock (70/30 Bd/St) 100 --Butadiene/Styrene Radial Teleblock (60/40 Bd/St) -- 100 Polystyrene 70 35 Alphamethylstyrene Polymer -- 35 Silica 30 30 Naphthenic Oil 300 250 3Ei6 Bentonite Clay (Western Type) 400 350 Zinc Stearate 0.~0 0.80 Antioxidant( ~ 0.70 0.70 Ethylene/Vinyl Acstate Copolymer(2) 30 --Ethylene/Vinyl Acetate Copolymer(3) -- 30 Iron Oxide 2 2 Furnace Black, ASTM N-550 0.5 0.5 Polyethylene Glycol, Molecular Weight About 540 3 3 Triethanolamine 6 6 943.00843.00 Good bond, but not rubber tear 4 Sec. 6 Sec.
Perfect bond with rubber tear 5-6 Sec. 7-lO Sec.
Too much penetration into carpet 8 Sec. 12 Sec.
*Ingredients are in parts by weight per 100 parts by weight of the thermoplastic elastomer (phr).
(l) Argus Chemica} Corp., Brooklyn, N.Y., Mark(R) 1589B.
(2) Melting point about 240F tll5C).
~3) Melting point about 220F ~104C).
EXAMPLE II
In another series of tests, yet another composition comprising a butadiene/styrene radial teleblock copolymer was utilized in two tests. In one test ethylene/vinyl acetate copolymer having a melting point of about 240F
(115C) was added to the composition whereas in the other test this material was not employed. The same mold, microwave generator and test procedure was employed except that in this particular case the molding composition was placed in the bottom of *he mold and the release sheet directly on top of the molding composition to thereby form a mat, such as an outdoor mat without carpeting adhered thereto. It is to be seen as a result of this test that the inclusion of ethylene/vinyl acetate copolymer reduced the minimum heating time to less than half of that required when the ethylene/vinyl acetate copolymer was not employed.
Table II
Outdoor Mat Compound
~3) Melting point about 220F ~104C).
EXAMPLE II
In another series of tests, yet another composition comprising a butadiene/styrene radial teleblock copolymer was utilized in two tests. In one test ethylene/vinyl acetate copolymer having a melting point of about 240F
(115C) was added to the composition whereas in the other test this material was not employed. The same mold, microwave generator and test procedure was employed except that in this particular case the molding composition was placed in the bottom of *he mold and the release sheet directly on top of the molding composition to thereby form a mat, such as an outdoor mat without carpeting adhered thereto. It is to be seen as a result of this test that the inclusion of ethylene/vinyl acetate copolymer reduced the minimum heating time to less than half of that required when the ethylene/vinyl acetate copolymer was not employed.
Table II
Outdoor Mat Compound
3* ~*
Butadiene/Styrene Radial Teleblock ~60/40 Bd/St) 100 100 Polystyrene 100 100 Silica 50 50 ~0 Naphthenic oil 250 250 Bentonite Clay 350 350 ~6~3~
Zinc Stearate 0.8 0.8 Antioxidant(l) 1.0 1.0 Red Iron Oxide 2.0 2.0 Carbon Black 0.5 0.5 Triethanolamine 4 4 Polyethylene glycol~2) 3 3 E-thylene/Vinylacetate Copolymer ~ 30 861.3 891.3 ~Excepting thermoplastic elastomer all ingredients are in phr.
(1) N-isopropyl-N'-phenyl-p-phenylenediamine.
(2) Molecular weight of about 540.
EXAMPLE III
Another test was conducted utilizing a bentonite clay from another manufacturer. The composition tested and the results of this test are set forth in Table III below.
Table III
Composition 5 Butadiene/Styrene Radial Teleblock~l) 150 Polystyrene 75 Silica 50 Bentonite Clay (350 mesh) 300 Naphthenic Oil 250 Int. Lubricant: Zinc Stearate 5 Ethylene/Vinylacetate Copolymer( ) 25 Stabilizers:
Nickel dibutyldithiocarbamate 0.5 Zinc dibutyldithiocarbamate 0.5 Antioxidant: Low Density Polyethylene( ) 1.0 Paraffin Wax 3 Dessicant(4) 20 Carbon Black 5 Sensitizers(5) 16 901 . O
Specific Gravity 1.29 300% Modulus 160 Tensile Stxength 200 Elongation 480 Shore A Hardness 43 Melt Index, Condition E 100+
*Parts by weight (1) 60/40 Bd/St + 50 phr oil (2) Melting point about 240F (115C) (3) Density of 0.92 g/cc, melt index of 70 (ASTM D 1238-65, Condition E) .~3.~ 3~
Butadiene/Styrene Radial Teleblock ~60/40 Bd/St) 100 100 Polystyrene 100 100 Silica 50 50 ~0 Naphthenic oil 250 250 Bentonite Clay 350 350 ~6~3~
Zinc Stearate 0.8 0.8 Antioxidant(l) 1.0 1.0 Red Iron Oxide 2.0 2.0 Carbon Black 0.5 0.5 Triethanolamine 4 4 Polyethylene glycol~2) 3 3 E-thylene/Vinylacetate Copolymer ~ 30 861.3 891.3 ~Excepting thermoplastic elastomer all ingredients are in phr.
(1) N-isopropyl-N'-phenyl-p-phenylenediamine.
(2) Molecular weight of about 540.
EXAMPLE III
Another test was conducted utilizing a bentonite clay from another manufacturer. The composition tested and the results of this test are set forth in Table III below.
Table III
Composition 5 Butadiene/Styrene Radial Teleblock~l) 150 Polystyrene 75 Silica 50 Bentonite Clay (350 mesh) 300 Naphthenic Oil 250 Int. Lubricant: Zinc Stearate 5 Ethylene/Vinylacetate Copolymer( ) 25 Stabilizers:
Nickel dibutyldithiocarbamate 0.5 Zinc dibutyldithiocarbamate 0.5 Antioxidant: Low Density Polyethylene( ) 1.0 Paraffin Wax 3 Dessicant(4) 20 Carbon Black 5 Sensitizers(5) 16 901 . O
Specific Gravity 1.29 300% Modulus 160 Tensile Stxength 200 Elongation 480 Shore A Hardness 43 Melt Index, Condition E 100+
*Parts by weight (1) 60/40 Bd/St + 50 phr oil (2) Melting point about 240F (115C) (3) Density of 0.92 g/cc, melt index of 70 (ASTM D 1238-65, Condition E) .~3.~ 3~
(4) 80 wt. /~ ground CaO in high flash process oil (Desi Cal,~
Basic Chemicals, Cleveland, Ohio)
Basic Chemicals, Cleveland, Ohio)
(5) Polyethylene glycol (Molecular Wt. about 540) + triethanolamine in equal proportions.
It has also been found that ground cork is an effective hygroscopic filler for use in the present invention. Ground cork has the additional ad-vantage of lowering the weight of the final product.
EXAMPLE IV
Table IV below shows another series of two tests in which the same bentonite clay as in ~xample III was utilized and a third test in which wood floux was substituted for part of -the bentonite clay. In addition to the suit-ability of wood flour as a hygroscopic filler, runs 7 and 8 show that ~ood results can be obtained in flow molding the compositions of the present inven-tion without the addition of polar sensitizers and run 6, as compared with runs 7 and 8, shows that overheating should be avoided when polar sensitizers are added. While it has been found that wood flour is not as effective as bentonite clay, it does in fact function in the same capacity and is useful in accordance with the present invention.
Table IV
Composition 6* 7* 8*
Butadiene/Styrene Radial Teleblock~l)150. 150. 150.
High Density Polyethylene100. 100. 100.
Bentonite Clay (350 mesh)300. 300. 200.
Wood Flour (Douglas Fir) - - lOO.
Ethylene-Propylene-Diene Terpoly~er Elastomer (2) 25. 25. 25.
Antioxidant?~w Density Polyethylene 1. 1. 1.
~ntioxidant 1. 1. 1.
Heat Stabilizer-Zinc Dibutyldithio-carbamate 1. 1. 1.
Paraffin Wax 2. 2. 2.
Dessicant: CaO dispersed in oil 15. 15. 15.
Int. Lubricant: Zinc Stearate 4. 4. 4.
Napthenic Oil 100. 100. 100.
TiO2 ~pigment~ 6. 6. 6.
Cou~arone Resin 10. 10. 10.
Sensitizers:
Triethanolamine 4 4.
Polyethylene Glycol~ ) 4. - -40 H.F. Flow-molded ln Compo Industries, Inc. Model J, 10 kw ,,,J/ 17 ~"
Machine, Output setting 78.
Time, Sec. 5 5 5 Grid Plate Rectifer, D.C. Milliamperes 0.67 0.62 0.59 Radio Frequency Voltage, D.C.
Microampere~ 78 78 78 Mold Flow GoodV.Good Good Molding Tlme Before Pitted Surface, Sec. 7 13 15 *Parts by weight (1) 52/48 Bd/St. + 60 phr oil (2) Density of 0.92 g/cc, melt index of 70 ~ASTM D 1238-65, Condition E) (3) Argus Chemical Corp, Brooklyn, N.Y., Mark(R) 1589B
(4) Molecular Wt. about 540 EXAMPLE V
In order to illustrate the advantages of the use of bentonite clay as a filler as opposed to whiting or calcium carbonate another series of tests was conducted comparing these two materials. ~gain, the same microwave generator, the same mold and the same general procedure were employed to produce a slab-type molded sheet.
At the outset it was observed that the whiting compositions werequite difficult to mix and had a sticky, very soft composition.
The results of these tests are set forth in Table V below wherein it is apparent that the articles molded from the compositions containing bentonite clay, in essentially the same mesh size as the whiting, were quite flexible whereas those produced with whiting, as an additive, were stiff and boardy. It is also apparent that the minimum heating time required was substantially greater for the compositions containing whiting.
Table V
Compound 9~; 10* 11* 12*
__ Butadiene/Styrene Radial Teleblock (70/30 Bd/St)** 150 150 1;0 150 Low Dens. Polyethylene(l)100 100 100 100 Silica 50 50 50 50 Naphthenic Oil 200 200 200 200 Zinc Stearate 0.8 0.8 0.8 0.8 Stabili~ers o.7(2) o.7(2~ o.95(3) o 95(3) Gamma-mercaptopropyltri-methoxysilane - - 4 4 ~3~
Polarizing Agents(4~ 8 8 8 8 Bentonite Clay, 325 Mesh 400 - - 400 Whiting - 400 400 909.5 909.5 913.75913.75 Mixing Observation OK Sticky, Sticky, OK
~. Soft V. Soft Minimum Heating Time (Seconds)12 20 60 35 Melt Flow, 5Kg at 190C327 589 610 216 Shore A Hardness 63-66 39-45 58-62 72-75 10 Other Physical Properties About Equal Molded Products Flexible Boardy Boardy Flexible *All ingredients are in parts by weight.
**Basic copolymers included 50 phr extender oil added during manufacture.
(1) Density of 0.92 g/cc, melt index of 70 (ASTM D 1238-65, Condition E).
(2) 0.3 Zinc dibutyldithiocarbamate 0.5 Nickel dibutyldithiocarbamate (3) 0.4 Zinc dibutyldithiocarbamate 0.55 Nickel dibutyldithiocarbamate (4~ 4 Triethanolamine 4 Polyethylene glycol of about 540 molecular weight.
EXAMPLE VI
In yet another series of tests, bentonite clay was compared with whiting in lower concentrations under essentially the same conditions as the previous examples.
Again, it is to be observed that the products containing the benton-ite clay were highly flexible whereas those produced from the compositions containing whiting were stiff. In addition, it can also be observed that again the minimum heating time for proper molding was substantially greater when utilizing whiting as opposed to bentonite clay.
Table VI
Compound 13* 14* 15* 16*
Butadiene/Styrene Radial Telebloc~
(60/40 Bd/St) 100 100 Butadiene/Styrene Radial Teleblock (52/48 Bd/St - 60 phr oil) - - 150 150 Alphamethylstyrene Polymer60 60 40 40 Silica 30 30 30 30 40 Naphthenlc Oil 70 70 75 75 Zinc Steflrate 0.3 0.3 0.75 0.75 Stabilizer(l) 0.5 0.5 0 5 0.5 Ethylene/Vinylacetate Copolymer(2) ~0 20 30 30 Desiccant(3) 15 15 15 15 Sensitizers~4) 3 3 6.5 6.5 Nitrile Rubber (5) - - 8 Bentonite Clay, 325 Mesh 45 - - 58 Whiting 343.8 343.8 413.75 413.75 Mixing Observation OK OK QK OK
Melt Flow, 2160g/190C48.8 102 32.8 13.9 HF Flow~Molded Tensils Slabs, 10kw M~del J Compo-Fit Machine:
Minimum Heating time 15lt 30" 20" 10"
300% Modulus, psi, 20" - - 160 220 Tensile, psi, 20" - - 400 460 Elongation, ~O~ 20" - - 660 640 Hardness, Shore A, 20" - - 62-71 72-79 Nolded Products Flexible Stiff Stiif Flexible -~Ingredients in phr ~based on 100 parts by weight of thermoplastic elastomer).
(1) 0.5 Tris(nonylphenyl)phosphîte.
(2) Melting point about 240F.
(3) 80 Wt. % Ground CaO in high flash process oil (Desi Cal~, Basic Chemicals, Cleveland, Ohio).
(4) 50/50 by weight triethanolamine and polyethylene glycol of about 540 molecular weight.
(5) Powde~ed butadiene-acrylonitrile elastomer, 50 Mooney viscosity, NL-4, 210F, (~ycar~ 1452 P-5Ds B.F. Goodrich Chemical Co., Cleveland, Ohio).
~XAMPIE VII
The effect of substituting carbon black for all or part of the hygroseopic filler was evaluated in the tests set forth in Table VII below:
Table VII
Composition 17 18 19 20 Butadiene/Styrene Radial Teleblock(l)140 140 140 140 Polystyrene 75 75 75 75 Silica 45 - 45 45 Bentonite (350 mesh) 300 300150 Carbon Black 45 150 300 Napthenic Oil 250 250250 250 Zinc Stearate 5 5 5 5 Ethylene/Vinylacetate(2) 25 25 25 25 StabiIizers:
Mickel Dibutyldithiocarba~ate0.50.5 0.5 0.5 Zinc Dibutyldithiocarbamate 0.50.5 0.5 0.5 Paraffin Wax 3 3 3 3 Sensitizers(3) 16 16 16 16 Desiccant: CaO dispersed in oil 20 20 20 20 Styrene/Butadiene(4) 15 15_ 15 15 3~36 895 895875 ~95 Calculated Specific Gravity 1.291.2~ 1.26 1.24 HFFM Time, Secs. 5 2 4 6 300% Modulus, psi 110 70 1~0 Tensile Strength, psi 150130 140 300 % Elongation 450 540300 190 Shore A Hardness 30 22 42 35 Melt Index Flow, 325 grams at 190C4.6 37.4 0.65 4.4 Nold Flow @ 2", Rating 1-5, 1 is Best 2 2 3 5 Time for Equivalent Mold Flow, Secs. 2" 2" 8" 8"
Scrub Test on White Paper, Marking Non- Non- Slight Heavy Oil Bleedout on Brown Paper After 3 weeks 51ightMedium Slight None After 6 weeks Medium Heavy Medium Slight ~1) 60/40 Bd/St + 50 phr oil (2) Molecular weight about 240 (3) Triethanolamine ~ Polyethylene glycol (Molecular Wt.
about 540) in equal portions (4) Emulsion polymerized flt 41~F containing 50 parts carbon black per 100 parts rubber.
It is to be observed from Table VII that, while carbon black has the effect of reducing the bleed out of extender oil, it has a number of disadvan-tages when compared with bentonite clay. Specifically, when 1/2 of the bentorl-ite clay was replaced with carbon black the time necessary for molding was increased and the melt flow of the composition was reduced. When the carbon black replaced all of the bentonite clay the tensile, modulus and hardness increased, as did the molding time necessary and mold flow was further reduced.
In addition, a molded sheet of the product produced heavy black marks when scrubbed on a light colored surface.
EX~MPLE VIII
Yet another series of comparative tests was conducted as set forth in Table VIII below:
Table VIII
Composition 21 2223 24 25 26 Butadiene/Styrene Radial Teleblock~l) 150 ) Polystyrene 75 ) SAME
Silica 45 ) Bentonite t350 mesh) 300 ) 40 Bentonite t325 mesh) 300 - - - -Royal King~ Clay (Hard China) - - 300 Suprex~ Clay ~Hard China) - - - 300 - -Gamaco~ Whiting - - - - 300 Paragon~ Clay (Sof-t China) - - - - - 300 Napthenic Oil 250 Zinc Stearate 5 Ethylene Vinylacetate Copolymer(2) 25 ) Stabilizers:
Nickel Dibutyldithio-carbamate 0.5) ~inc D~tyldithiocarbamate O.5) SAME
Antioxidant 0.5) Paraffin Wax 4) 3 Styrene/B~diene( 16 Dessicant 20 Carbon Black 5 ~95.5 895.5 895.5 895.5 895.5 895.5 Specific Gravity 1.29 1.29 1.29 1.29 1.29 1.29 Mixing Time, Min. 10 14 14 12 - 1~
Mixing Time, Dumping, Charact. Good Good Poor Fair Would Fair not mix Heating Time Grid Plate Rectifier, Max.
Secs.
3 .54 .62 .36 .38 - .36
It has also been found that ground cork is an effective hygroscopic filler for use in the present invention. Ground cork has the additional ad-vantage of lowering the weight of the final product.
EXAMPLE IV
Table IV below shows another series of two tests in which the same bentonite clay as in ~xample III was utilized and a third test in which wood floux was substituted for part of -the bentonite clay. In addition to the suit-ability of wood flour as a hygroscopic filler, runs 7 and 8 show that ~ood results can be obtained in flow molding the compositions of the present inven-tion without the addition of polar sensitizers and run 6, as compared with runs 7 and 8, shows that overheating should be avoided when polar sensitizers are added. While it has been found that wood flour is not as effective as bentonite clay, it does in fact function in the same capacity and is useful in accordance with the present invention.
Table IV
Composition 6* 7* 8*
Butadiene/Styrene Radial Teleblock~l)150. 150. 150.
High Density Polyethylene100. 100. 100.
Bentonite Clay (350 mesh)300. 300. 200.
Wood Flour (Douglas Fir) - - lOO.
Ethylene-Propylene-Diene Terpoly~er Elastomer (2) 25. 25. 25.
Antioxidant?~w Density Polyethylene 1. 1. 1.
~ntioxidant 1. 1. 1.
Heat Stabilizer-Zinc Dibutyldithio-carbamate 1. 1. 1.
Paraffin Wax 2. 2. 2.
Dessicant: CaO dispersed in oil 15. 15. 15.
Int. Lubricant: Zinc Stearate 4. 4. 4.
Napthenic Oil 100. 100. 100.
TiO2 ~pigment~ 6. 6. 6.
Cou~arone Resin 10. 10. 10.
Sensitizers:
Triethanolamine 4 4.
Polyethylene Glycol~ ) 4. - -40 H.F. Flow-molded ln Compo Industries, Inc. Model J, 10 kw ,,,J/ 17 ~"
Machine, Output setting 78.
Time, Sec. 5 5 5 Grid Plate Rectifer, D.C. Milliamperes 0.67 0.62 0.59 Radio Frequency Voltage, D.C.
Microampere~ 78 78 78 Mold Flow GoodV.Good Good Molding Tlme Before Pitted Surface, Sec. 7 13 15 *Parts by weight (1) 52/48 Bd/St. + 60 phr oil (2) Density of 0.92 g/cc, melt index of 70 ~ASTM D 1238-65, Condition E) (3) Argus Chemical Corp, Brooklyn, N.Y., Mark(R) 1589B
(4) Molecular Wt. about 540 EXAMPLE V
In order to illustrate the advantages of the use of bentonite clay as a filler as opposed to whiting or calcium carbonate another series of tests was conducted comparing these two materials. ~gain, the same microwave generator, the same mold and the same general procedure were employed to produce a slab-type molded sheet.
At the outset it was observed that the whiting compositions werequite difficult to mix and had a sticky, very soft composition.
The results of these tests are set forth in Table V below wherein it is apparent that the articles molded from the compositions containing bentonite clay, in essentially the same mesh size as the whiting, were quite flexible whereas those produced with whiting, as an additive, were stiff and boardy. It is also apparent that the minimum heating time required was substantially greater for the compositions containing whiting.
Table V
Compound 9~; 10* 11* 12*
__ Butadiene/Styrene Radial Teleblock (70/30 Bd/St)** 150 150 1;0 150 Low Dens. Polyethylene(l)100 100 100 100 Silica 50 50 50 50 Naphthenic Oil 200 200 200 200 Zinc Stearate 0.8 0.8 0.8 0.8 Stabili~ers o.7(2) o.7(2~ o.95(3) o 95(3) Gamma-mercaptopropyltri-methoxysilane - - 4 4 ~3~
Polarizing Agents(4~ 8 8 8 8 Bentonite Clay, 325 Mesh 400 - - 400 Whiting - 400 400 909.5 909.5 913.75913.75 Mixing Observation OK Sticky, Sticky, OK
~. Soft V. Soft Minimum Heating Time (Seconds)12 20 60 35 Melt Flow, 5Kg at 190C327 589 610 216 Shore A Hardness 63-66 39-45 58-62 72-75 10 Other Physical Properties About Equal Molded Products Flexible Boardy Boardy Flexible *All ingredients are in parts by weight.
**Basic copolymers included 50 phr extender oil added during manufacture.
(1) Density of 0.92 g/cc, melt index of 70 (ASTM D 1238-65, Condition E).
(2) 0.3 Zinc dibutyldithiocarbamate 0.5 Nickel dibutyldithiocarbamate (3) 0.4 Zinc dibutyldithiocarbamate 0.55 Nickel dibutyldithiocarbamate (4~ 4 Triethanolamine 4 Polyethylene glycol of about 540 molecular weight.
EXAMPLE VI
In yet another series of tests, bentonite clay was compared with whiting in lower concentrations under essentially the same conditions as the previous examples.
Again, it is to be observed that the products containing the benton-ite clay were highly flexible whereas those produced from the compositions containing whiting were stiff. In addition, it can also be observed that again the minimum heating time for proper molding was substantially greater when utilizing whiting as opposed to bentonite clay.
Table VI
Compound 13* 14* 15* 16*
Butadiene/Styrene Radial Telebloc~
(60/40 Bd/St) 100 100 Butadiene/Styrene Radial Teleblock (52/48 Bd/St - 60 phr oil) - - 150 150 Alphamethylstyrene Polymer60 60 40 40 Silica 30 30 30 30 40 Naphthenlc Oil 70 70 75 75 Zinc Steflrate 0.3 0.3 0.75 0.75 Stabilizer(l) 0.5 0.5 0 5 0.5 Ethylene/Vinylacetate Copolymer(2) ~0 20 30 30 Desiccant(3) 15 15 15 15 Sensitizers~4) 3 3 6.5 6.5 Nitrile Rubber (5) - - 8 Bentonite Clay, 325 Mesh 45 - - 58 Whiting 343.8 343.8 413.75 413.75 Mixing Observation OK OK QK OK
Melt Flow, 2160g/190C48.8 102 32.8 13.9 HF Flow~Molded Tensils Slabs, 10kw M~del J Compo-Fit Machine:
Minimum Heating time 15lt 30" 20" 10"
300% Modulus, psi, 20" - - 160 220 Tensile, psi, 20" - - 400 460 Elongation, ~O~ 20" - - 660 640 Hardness, Shore A, 20" - - 62-71 72-79 Nolded Products Flexible Stiff Stiif Flexible -~Ingredients in phr ~based on 100 parts by weight of thermoplastic elastomer).
(1) 0.5 Tris(nonylphenyl)phosphîte.
(2) Melting point about 240F.
(3) 80 Wt. % Ground CaO in high flash process oil (Desi Cal~, Basic Chemicals, Cleveland, Ohio).
(4) 50/50 by weight triethanolamine and polyethylene glycol of about 540 molecular weight.
(5) Powde~ed butadiene-acrylonitrile elastomer, 50 Mooney viscosity, NL-4, 210F, (~ycar~ 1452 P-5Ds B.F. Goodrich Chemical Co., Cleveland, Ohio).
~XAMPIE VII
The effect of substituting carbon black for all or part of the hygroseopic filler was evaluated in the tests set forth in Table VII below:
Table VII
Composition 17 18 19 20 Butadiene/Styrene Radial Teleblock(l)140 140 140 140 Polystyrene 75 75 75 75 Silica 45 - 45 45 Bentonite (350 mesh) 300 300150 Carbon Black 45 150 300 Napthenic Oil 250 250250 250 Zinc Stearate 5 5 5 5 Ethylene/Vinylacetate(2) 25 25 25 25 StabiIizers:
Mickel Dibutyldithiocarba~ate0.50.5 0.5 0.5 Zinc Dibutyldithiocarbamate 0.50.5 0.5 0.5 Paraffin Wax 3 3 3 3 Sensitizers(3) 16 16 16 16 Desiccant: CaO dispersed in oil 20 20 20 20 Styrene/Butadiene(4) 15 15_ 15 15 3~36 895 895875 ~95 Calculated Specific Gravity 1.291.2~ 1.26 1.24 HFFM Time, Secs. 5 2 4 6 300% Modulus, psi 110 70 1~0 Tensile Strength, psi 150130 140 300 % Elongation 450 540300 190 Shore A Hardness 30 22 42 35 Melt Index Flow, 325 grams at 190C4.6 37.4 0.65 4.4 Nold Flow @ 2", Rating 1-5, 1 is Best 2 2 3 5 Time for Equivalent Mold Flow, Secs. 2" 2" 8" 8"
Scrub Test on White Paper, Marking Non- Non- Slight Heavy Oil Bleedout on Brown Paper After 3 weeks 51ightMedium Slight None After 6 weeks Medium Heavy Medium Slight ~1) 60/40 Bd/St + 50 phr oil (2) Molecular weight about 240 (3) Triethanolamine ~ Polyethylene glycol (Molecular Wt.
about 540) in equal portions (4) Emulsion polymerized flt 41~F containing 50 parts carbon black per 100 parts rubber.
It is to be observed from Table VII that, while carbon black has the effect of reducing the bleed out of extender oil, it has a number of disadvan-tages when compared with bentonite clay. Specifically, when 1/2 of the bentorl-ite clay was replaced with carbon black the time necessary for molding was increased and the melt flow of the composition was reduced. When the carbon black replaced all of the bentonite clay the tensile, modulus and hardness increased, as did the molding time necessary and mold flow was further reduced.
In addition, a molded sheet of the product produced heavy black marks when scrubbed on a light colored surface.
EX~MPLE VIII
Yet another series of comparative tests was conducted as set forth in Table VIII below:
Table VIII
Composition 21 2223 24 25 26 Butadiene/Styrene Radial Teleblock~l) 150 ) Polystyrene 75 ) SAME
Silica 45 ) Bentonite t350 mesh) 300 ) 40 Bentonite t325 mesh) 300 - - - -Royal King~ Clay (Hard China) - - 300 Suprex~ Clay ~Hard China) - - - 300 - -Gamaco~ Whiting - - - - 300 Paragon~ Clay (Sof-t China) - - - - - 300 Napthenic Oil 250 Zinc Stearate 5 Ethylene Vinylacetate Copolymer(2) 25 ) Stabilizers:
Nickel Dibutyldithio-carbamate 0.5) ~inc D~tyldithiocarbamate O.5) SAME
Antioxidant 0.5) Paraffin Wax 4) 3 Styrene/B~diene( 16 Dessicant 20 Carbon Black 5 ~95.5 895.5 895.5 895.5 895.5 895.5 Specific Gravity 1.29 1.29 1.29 1.29 1.29 1.29 Mixing Time, Min. 10 14 14 12 - 1~
Mixing Time, Dumping, Charact. Good Good Poor Fair Would Fair not mix Heating Time Grid Plate Rectifier, Max.
Secs.
3 .54 .62 .36 .38 - .36
6 .5~ .56 .36 .36 - .34 Arc Arc 12 - - .36 .36 - - - - - .35 Mold Flow Charact.
Secs.
3 Good Good No Flow No Flow- No Flow 6 Excel- Excel- (Little (Little- (Little lent lent Flow) Flow) Flow) Over- Over-heat heat 12 - - Fair Fair - - - - - Fair Physical Properties 30% Modulus, psi 130 130 190 200 - 150 Tensile Strength,psi 200 lg0 200 220 - l70 Elongation, % 460 490 330 390 - 370 Shore A Hardness 34 39 39 34 - 32 (1) 60/40 Bd/St ~ 50 phr oil (2) Molecular Weight about 240 (3) Argus Chemical Corp., Brooklyn, N.Y., Mark(R) 1589B
(4) Emulsion polymerized at 41F containing 50 parts carbon black per 100 parts rubber (5) 80 Wt. % CaO in high flash process oil (~esi Cal, Basic Chemicals, Cleveland, Ohio) ~Trademark of company indicated on following page `~ 22 3~
Table IX shows the comparative moisture contents of the fillers utilized in the previous comparative examples. While the nonhygroscopic Hi Sil 233~ (PPG Industries) (Silica) and Royal King~ (H. M. Royal, Inc.) Clay (Hard China) exhibit high initial water contents, it is obvious from the previous examples that these materials were inferior to the hygroscopic fillers of the present invention, due to the facts that the absorbed water is readily driven off as soon as the temperature is above the boiling point of water, usually in the preparation of the compositions prior to molding, and any chemically-bound water, which is not driven off apparently does not function in the same manner, in the present process, as does absorbed water.
Table IX
Filler ~E~ ____ % Moisture __ __ _ 1. Royal King Clay (Hard China) H. M. Royal, Inc. 14.0 2. Western Bentonite H. M. Royal, Inc. 9.0 3. Hi Sil 233 (Silica) PPG Industries 5.3 4. Philblack N550~ (Carbon Black) Phillips Petroleum 1.0 Max.
5. Wood Flour Wood ~lour, Inc. 5.0-8.0 6. Ground Cork Dodge Cork Company 4.0-9.0
Secs.
3 Good Good No Flow No Flow- No Flow 6 Excel- Excel- (Little (Little- (Little lent lent Flow) Flow) Flow) Over- Over-heat heat 12 - - Fair Fair - - - - - Fair Physical Properties 30% Modulus, psi 130 130 190 200 - 150 Tensile Strength,psi 200 lg0 200 220 - l70 Elongation, % 460 490 330 390 - 370 Shore A Hardness 34 39 39 34 - 32 (1) 60/40 Bd/St ~ 50 phr oil (2) Molecular Weight about 240 (3) Argus Chemical Corp., Brooklyn, N.Y., Mark(R) 1589B
(4) Emulsion polymerized at 41F containing 50 parts carbon black per 100 parts rubber (5) 80 Wt. % CaO in high flash process oil (~esi Cal, Basic Chemicals, Cleveland, Ohio) ~Trademark of company indicated on following page `~ 22 3~
Table IX shows the comparative moisture contents of the fillers utilized in the previous comparative examples. While the nonhygroscopic Hi Sil 233~ (PPG Industries) (Silica) and Royal King~ (H. M. Royal, Inc.) Clay (Hard China) exhibit high initial water contents, it is obvious from the previous examples that these materials were inferior to the hygroscopic fillers of the present invention, due to the facts that the absorbed water is readily driven off as soon as the temperature is above the boiling point of water, usually in the preparation of the compositions prior to molding, and any chemically-bound water, which is not driven off apparently does not function in the same manner, in the present process, as does absorbed water.
Table IX
Filler ~E~ ____ % Moisture __ __ _ 1. Royal King Clay (Hard China) H. M. Royal, Inc. 14.0 2. Western Bentonite H. M. Royal, Inc. 9.0 3. Hi Sil 233 (Silica) PPG Industries 5.3 4. Philblack N550~ (Carbon Black) Phillips Petroleum 1.0 Max.
5. Wood Flour Wood ~lour, Inc. 5.0-8.0 6. Ground Cork Dodge Cork Company 4.0-9.0
7. Suprex~ Clay (Hard China) J. M. Huber 1.0 Max.
8. Gamaco~ ~hiting Georgia Narble 1.0 Max.
9. Paragon~ Clay (Soft China) J. M. Huber 1.0 Max.
Trademark of supplier indicated Some of the advantages oE the hygroscopic fillers over nonhygroscopic flllers, such as whiting and china clay, etc. can be summarized as follows:
Shorter mixing times.
No stickiness in the mixing chamber or on roll mills.
Shorter heating time in a high frequency field.
More suitable melt flow, i.e., higher than china clay and lower than whiting.
Higher hardness than whiting and about the same as china clay.
Equal or slightly better stress/strain properties but considerably better tear (hand test).
Considerably better flexibility than whiting and especially china clay.
~hile specific materials, amounts thereof and operating procedures have been referred to herein, numerous variations and modifications thereof will be apparent -to one skilled in the art and the present invention is con-sidered to include such variations and modifications.
p~
~3
Trademark of supplier indicated Some of the advantages oE the hygroscopic fillers over nonhygroscopic flllers, such as whiting and china clay, etc. can be summarized as follows:
Shorter mixing times.
No stickiness in the mixing chamber or on roll mills.
Shorter heating time in a high frequency field.
More suitable melt flow, i.e., higher than china clay and lower than whiting.
Higher hardness than whiting and about the same as china clay.
Equal or slightly better stress/strain properties but considerably better tear (hand test).
Considerably better flexibility than whiting and especially china clay.
~hile specific materials, amounts thereof and operating procedures have been referred to herein, numerous variations and modifications thereof will be apparent -to one skilled in the art and the present invention is con-sidered to include such variations and modifications.
p~
~3
Claims (54)
IS CLAIMED ARE DEFINED AS FOLLOWS:
1. An unvulcanized, pressure and heat moldable composition com-prising:
100 parts by weight of a thermoplastic elastomer;
at least about 10 parts by weight of an extender oil per 100 parts by weight of said thermoplastic elastomer; and at least about 20 parts by weight of at least one solid, hygroscopic filler, having greater than 1 percent by weight of absorbed water and being capable of retaining a substantial portion of said absorbed water at a tempera-ture above 100°C and utilized in the preparation of said composition, per 100 parts by weight of said thermoplastic elastomer;
the ratio of said extender oil to said hygroscopic filler being from about 0.3 to about 3.
100 parts by weight of a thermoplastic elastomer;
at least about 10 parts by weight of an extender oil per 100 parts by weight of said thermoplastic elastomer; and at least about 20 parts by weight of at least one solid, hygroscopic filler, having greater than 1 percent by weight of absorbed water and being capable of retaining a substantial portion of said absorbed water at a tempera-ture above 100°C and utilized in the preparation of said composition, per 100 parts by weight of said thermoplastic elastomer;
the ratio of said extender oil to said hygroscopic filler being from about 0.3 to about 3.
2. A composition in accordance with claim 1 wherein the thermo-plastic elastomer is a conjugated diene/vinyl aromatic block copolymer.
3. A composition in accordance with claim 2 wherein the block co-polymer is selected from the group consisting of linear block and radial tele-block copolymers.
4. A composition in accordance with claim 3 wherein the copolymer is a radial teleblock copolymer.
5. A composition in accordance with claim 1 wherein the thermo-plastic elastomer is a butadiene/styrene block copolymer having a butadiene/-styrene weight ratio between about 85/15 to about 45/55.
6. A composition in accordance with claim 1 wherein the composition contains up to about 150 parts by weight of a solid resinous polymer per 100 parts by weight of the thermoplastic elastomer.
7. A composition in accordance with claim 6 wherein the solid resinous polymer is selected from the group consisting of homopolymers of a vinyl-substituted aromatic compound and copolymers of said compound with a copolymerizable compound.
8. A composition in accordance with claim 7 wherein the copolymeriz-able compound is a compound selected from the group consisting of acrylonitrile and a conjugated diene.
9. A composition in accordance with claim 1 wherein the thermoplastic elastomer is an oil-extended butadiene/styrene block copolymer.
10. A composition in accordance with claim 1 wherein the composition contains a polar agent in an amount sufficient to significantly increase the microwave energy absorptivity of said composition and to render said composition moldable at pressures less than about 200 psi.
11. A composition in accordance with claim 10 wherein the composition contains an ethylene/vinyl acetate copolymer in an amount sufficient to significantly reduce the molding time.
12. A composition in accordance with claim 10 wherein the polar compound is present in an amount sufficient to produce a composition having a molding time between about one second and sixty seconds.
13. A composition in accordance with claim 1 wherein the extender oil is present in an amount between about 250 to about 350 parts by weight per 100 parts by weight of the thermoplastic elastomer, the hygroscopic filler is present in an amount between about 350 to about 500 parts by weight per 100 parts by weight of said thermoplastic elastomer and the oil/filler ratio is between about 0.5 and about 1Ø
14. A composition in accordance with claim 1, 2 or 3 wherein the hygroscopic filler has greater than about 4.0 percent by weight of absorbed water.
15. A composition in accordance with claim 1, 2 or 3 wherein the hygroscopic filler is capable of retaining a substantial portion of the absorbed water at a temperature up to the temperature to be utilized in the molding of said composition.
16. A composition in accordance with claim 1, 2 or 3 wherein the hygroscopic filler is bentonite clay.
17. A composition in accordance with claim 1, 2 or 3 wherein the hygroscopic filler is wood flour.
18. A composition in accordance with claim 1, 2 or 3 wherein the hygroscopic filler is ground cork.
19. A method of flow molding a thermoplastic elastomer composition comprising:
forming a mixture comprising;
100 parts by weight of a thermoplastic elastomer;
at least about 10 parts by weight of an extender oil per 100 parts by weight of the said thermoplastic elastomer; and at least about 20 parts by weight of at least one solid, hygroscopic filler, having greater than 1 percent by weight of absorbed water and being capable of retaining a substantial portion of said absorbed water at a tempera-ture above 100°C and utilized in the preparation of said composition for molding, per 100 parts by weight of said thermoplastic elastomer;
the ratio of said extender oil to said hygroscopic filler being from about 0.3 to about 3;
disposing said mixture in a mold;
exposing said mixture to microwave energy while simultaneously applying pressure below about 200 psi for a period of time sufficient to melt said mixture and cause the same to flow into the interstices of the mold.
forming a mixture comprising;
100 parts by weight of a thermoplastic elastomer;
at least about 10 parts by weight of an extender oil per 100 parts by weight of the said thermoplastic elastomer; and at least about 20 parts by weight of at least one solid, hygroscopic filler, having greater than 1 percent by weight of absorbed water and being capable of retaining a substantial portion of said absorbed water at a tempera-ture above 100°C and utilized in the preparation of said composition for molding, per 100 parts by weight of said thermoplastic elastomer;
the ratio of said extender oil to said hygroscopic filler being from about 0.3 to about 3;
disposing said mixture in a mold;
exposing said mixture to microwave energy while simultaneously applying pressure below about 200 psi for a period of time sufficient to melt said mixture and cause the same to flow into the interstices of the mold.
20. A method in accordance with claim 19 wherein the thermoplastic copolymer is a conjugated diene/vinyl aromatic block copolymer.
21. A method in accordance with claim 20 wherein the copolymer is selected from the group consisting of linear block and radial teleblock copolymers.
22. A method in accordance with claim 21 wherein the copolymer is a radial teleblock copolymer.
23. A method in accordance with claim 19 wherein the thermoplastic elastomer is a butadiene/styrene block copolymer having a butadiene/styrene weight ratio of about 85/15 to about 45/55.
24. A method in accordance with claim 19 wherein the mixture contains up to about 150 parts by weight of a solid resinous polymer per 100 parts by weight of the thermoplastic elastomer.
25. A method in accordance with claim 24 when the solid resinous polymer is selected from the group consisting of homopolymers of a vinyl-substituted aromatic compound and copolymers of said compound with a copolymerizable compound.
26. A method in accordance with claim 25 wherein the copolymerizable compound is a compound selected from the group consisting of acrylonitrile and a conjugated diene.
27. A method in accordance with claim 19 wherein the thermoplastic elastomer is an oil extended butadiene/styrene block copolymer.
28. A method in accordance with claim 19 wherein the mixture contains ethylene/vinyl acetate copolymer in an amount sufficient to significantly reduce the molding time.
29. A method in accordance with claim 19 wherein the molding time is between about one second and about sixty seconds.
30. A method in accordance with claim 19 wherein the mixture contains about 250 to about 350 parts by weight of extender oil per 100 parts by weight of the thermoplastic elastomer, about 350 to about 500 parts by weight of the hygroscopic filler per 100 parts by weight of said thermoplastic elastomer and the oil/filler ratio is between about 0.5 and about 1Ø
31. A method in accordance with claim 19 wherein the mixture contains a polar compound in an amount sufficient to significantly reduce the molding time.
32. A method in accordance with claim 19, 20 or 21 wherein the hygroscopic filler has greater than about 4.0 percent by weight of absorbed water.
33. A method in accordance with claim 19, 20 or 21 wherein the hygroscopic filler is capable of retaining a substantial portion of the absorbed water at the temperature utilized in the molding.
34. A method in accordance with claim 19, 20 or 21 wherein the hygroscopic filler is bentonite clay.
35. A method in accordance with claim 19, 20 or 21 wherein the hygroscopic filler is wood flour.
36. A method in accordance with claim 19, 20 or 21 wherein the hygroscopic filler is ground cork.
37. A flexible, molded thermoplastic elastomer article comprising:
100 parts by weight of a thermoplastic elastomer;
at least about 10 parts by weight of an extender oil per 100 parts by weight of said thermoplastic elastomer;
and at least 20 parts by weight of at least one solid, hygroscopic filler, having greater than 1 percent by weight of absorbed water and being capable of retaining a substantial portion of said absorbed water at a tempera-ture above 100°C and utilized in the preparation of said article prior the molding thereof, per 100 parts by weight of said thermoplastic elastomer;
the ratio of said extender oil to said hygroscopic filler being about 0.3 to about 3.
100 parts by weight of a thermoplastic elastomer;
at least about 10 parts by weight of an extender oil per 100 parts by weight of said thermoplastic elastomer;
and at least 20 parts by weight of at least one solid, hygroscopic filler, having greater than 1 percent by weight of absorbed water and being capable of retaining a substantial portion of said absorbed water at a tempera-ture above 100°C and utilized in the preparation of said article prior the molding thereof, per 100 parts by weight of said thermoplastic elastomer;
the ratio of said extender oil to said hygroscopic filler being about 0.3 to about 3.
38. An article in accordance with claim 37 wherein the thermoplastic elastomer is a conjugated diene/vinyl aromatic block copolymer.
39. An article in accordance with claim 38 wherein the copolymer is selected from the group consisting of linear block and radial teleblock co-polymers.
40. An article in accordance with claim 39 wherein the copolymer is a radial teleblock copolymer.
41. An article in accordance with claim 37 wherein the thermoplastic elastomer is a butadiene/styrene block copolymer having a butadiene/styrene weight ratio of about 85/15 to about 45/55.
42. An article in accordance with claim 37 wherein the article contains up to about 150 parts by weight of a solid resinous polymer per 100 parts by weight of the thermoplastic elastomer.
43. An article in accordance with claim 42 wherein the solid resinous polymer is selected from the group consisting of a homopolymer of a vinyl-substituted aromatic compound and copolymers of said compound with a copolymerizable compound.
44. An article in accordance with claim 43 wherein the co-polymerizable compound is a compound selected from the group consisting of acrylonitrile and a conjugated diene.
45. An article in accordance with claim 37 wherein the thermoplastic elastomer is an oil extended butadiene/styrene block copolymer.
46. An article in accordance with claim 37 which additionally in-cludes a polar agent in an amount sufficient to significantly increase the microwave energy absorptivity of the article and render the article moldable at a pressure less than about 200 psi and said article has been flow molded by exposure to microwave energy.
47. An article in accordance with claim 46 wherein the article con-tains an ethylene/vinyl acetate copolymer in an amount sufficient to signi-cantly reduce the time required for molding of the same.
48. An article in accordance with claim 46 wherein the article has been molded in a time between about one second and about sixty seconds.
49. An article in accordance with claim 37 wherein the oil is present in amounts of about 250 to 350 parts by weight per 100 parts by weight of the thermoplastic elastomer, the hygroscopic filler is present in amounts of about 350 to about 500 parts by weight per 100 parts by weight of said thermoplastic elastomer and the oil/filler ratio is between about 0.5 and about 1Ø
50. An article in accordance with claim 37, 38 or 39 wherein the hygroscopic filler has greater than about 4.0 percent by weight of absorbed water.
51. An article in accordance with claim 37, 38 or 39 wherein the hygroscopic filler is capable of retaining a substantial portion of the absorbed water at the temperature at which said article was molded.
52. An article in accordance with claim 37, 38 or 39 wherein the hygroscopic filler is bentonite clay.
53. An article in accordance with claim 37, 38 or 39 wherein the hygroscopic filler is wood flour.
54. An article in accordance with claim 37, 38 or 39 wherein the hygroscopic filler is ground cork.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000362748A CA1160386A (en) | 1980-10-20 | 1980-10-20 | Thermoplastic elastomeric composition, product and method of manufacture |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000362748A CA1160386A (en) | 1980-10-20 | 1980-10-20 | Thermoplastic elastomeric composition, product and method of manufacture |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1160386A true CA1160386A (en) | 1984-01-10 |
Family
ID=4118195
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000362748A Expired CA1160386A (en) | 1980-10-20 | 1980-10-20 | Thermoplastic elastomeric composition, product and method of manufacture |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1160386A (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US8691340B2 (en) | 2008-12-31 | 2014-04-08 | Apinee, Inc. | Preservation of wood, compositions and methods thereof |
| US9878464B1 (en) | 2011-06-30 | 2018-01-30 | Apinee, Inc. | Preservation of cellulosic materials, compositions and methods thereof |
-
1980
- 1980-10-20 CA CA000362748A patent/CA1160386A/en not_active Expired
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US8691340B2 (en) | 2008-12-31 | 2014-04-08 | Apinee, Inc. | Preservation of wood, compositions and methods thereof |
| US9314938B2 (en) | 2008-12-31 | 2016-04-19 | Apinee, Inc. | Preservation of wood, compositions and methods thereof |
| US9878464B1 (en) | 2011-06-30 | 2018-01-30 | Apinee, Inc. | Preservation of cellulosic materials, compositions and methods thereof |
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