Classifications

• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
  • C08F230/00—Copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and containing phosphorus, selenium, tellurium or a metal
  • C08F230/04—Copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and containing phosphorus, selenium, tellurium or a metal containing a metal
  • C08F230/08—Copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and containing phosphorus, selenium, tellurium or a metal containing a metal containing silicon
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
  • C08F290/00—Macromolecular compounds obtained by polymerising monomers on to polymers modified by introduction of aliphatic unsaturated end or side groups
  • C08F290/02—Macromolecular compounds obtained by polymerising monomers on to polymers modified by introduction of aliphatic unsaturated end or side groups on to polymers modified by introduction of unsaturated end groups
  • C08F290/06—Polymers provided for in subclass C08G
  • C08F290/068—Polysiloxanes

Definitions

• This invention relates to an improved powder- free acrylic based emulsion copolymer composition that can be used as a coating for rubber articles.
• the coating assists in the removal of the article from the mold and facilitates dry donning.
• rubber articles such as gloves were manufactured by dipping a former or mold into a rubber latex. These processes often. included the use of a powdered lubricant, such as talc, cornstarch, or clay. Typically, the powder was incorporated into either a coagulant or into a release slurry.
• a coagulant is a compound that coagulates a layer-forming emulsion or dispersion to form a thicker layer than it would normally do otherwise.
• a release slurry is a slurry containing powder which is applied to the article prior to removal from the former.
• the use of powder in the coagulant or release slurry served two important purposes. First, powder made it easier to strip the resulting article from the former. With respect to gloves, removal from the mold is often difficult because cured latex gloves tend to be tacky and adhere to the mold. However, the use of powder reduced the tackiness or stickiness of the gloves and improved stripping. Second, powder facilitated donning in certain articles such as gloves.
• Halogenation produces articles having a powder-free clean surface.
• chlorination is widely used to make clean-room gloves, powder-free surgical gloves and powder-free examination gloves.
• articles produced using chlorination are powder-free and exhibit good dry donning characteristics, they are economically more expensive to produce due to the number of chlorination steps, turning steps, and drying processes involved in the manufacture.
• halogenated articles While halogenation can be used to facilitate donning, halogenated articles possess many disadvantages. Halogenated articles tend to discolor and age poorly both in storage and in use. In fact, discoloration can begin almost immediately, and within a month, the halogenated surface may become hard, brittle and brown in color. Additionally, chlorine is considered to be a toxic chemical and disposal of materials containing this element presents numerous environmental issues.
• the disadvantages of chlorination are recognized in U.S. Patent 5,284,607. This patent discloses a process for making a multi-layered, powder-free medical glove. The glove is made with an acid-soluble powder, and once fully formed, stripped from the former and reversed so that the first layer is on the outside.
• the glove is then treated with an acid, such as nitric acid, to remove the acid-soluble powder.
• an acid such as nitric acid
• the glove is rinsed with water and treated with bleach to chlorinate the inner and outer glove surface.
• the bleach does not cause the glove to have the excessively slippery outer surface that typically results when chlorination is used.
• U.S. Patent 4,310,928 discloses a talc free surgeon's glove.
• the glove is made by dipping a former into a coagulant solution containing a lipo compound and a surfactant and then into latex to form a glove.
• U.S. Patent 4,499,154 discloses another method of making a powder-free article.
• This patent details a process for making a rubber article by dipping a former into compounded latex, leaching the article, priming the article with an acid, neutralizing the article with water or an aqueous alkali, applying a hydrophilic coating, heating the article to fix the coating, curing the rubber, stripping the article from the former and applying a solution of surfactant materials and silicone. While this process produces a powder-free article, the number of steps involved makes the process unduly expensive and the low molecular weight components (surfactants and silicone) could cause contamination.
• Patent 5,138,719 discloses a method of making powder-free gloves, finger stalls and other protective articles constructed from latex and microcapsules.
• the microcapsules are dispersed and arranged in the latex to form a concentration gradient, with the concentration of the microcapsules increasing progressively from the outer surface to the inner surface of the article.
• the high concentration of the microcapsules at the inner surface provides good sliding properties and facilitates donning without the need for powder.
• the microcapsules may contain a pharmaceutically active substance such as nonoxynol, moroxydine hydrochloride, vidarabine to provide viricidal activity against diseases such as AIDS or herpes. See U.S. Patent 5,024,852.
• EP 0574160A1 discloses a method for making a powder-free, wet and dry donnable, multi-layered article having a first layer formed from natural rubber, a second layer formed from natural rubber, polyurethane, poly(acrylamide/acrylic acid) and polyethylene oxide, and a third layer of an acrylic copolymer and fluorocarbon telomer resin.
• a different process for making rubber gloves alleged to have good donning properties is disclosed in Kavalir et al., U.S. Patents 3,286,011 and 3,411,982. The disclosures of these patents are the same.
• These patents a coating composition comprising a mixed latex which is approximately 1:1 on a weight basis of a rubber latex and certain resinous polymer latices.
• acrylic ester latices are certain acrylic ester latices.
• the compositions of the patent are suggested for use as being former coatings and as coatings for the inner surfaces of rubber gloves to impart improved donning characteristics.
• the acrylic ester latices used by the patentees in their process are mixtures of acrylic ester latices.
• Kavalir et al. patents One of the teachings of the Kavalir et al. patents is that high concentrations of coagulating salts may be incorporated into the coating compositions of the invention.
• the use of a water soluble non-ionic surfactants incorporated into the compositions of the patent allows for the introduction of large quantities of coagulating salts such as calcium nitrate without resulting in the destabilization of the compositions.
• the patentees stress that the resinous polymer latices alone without the rubber latex are inoperative.
• An object of the present invention is to provide an improved powder-free acrylic based emulsion composition for coating rubber articles.
• the improved coating composition of this invention allows for the easy removal of the articles from the former upon which they are produced.
• Gloves produced by using the improved composition of this invention exhibit excellent dry and some good wet donning characteristics.
• the present invention involves an improved powder-free acrylic based emulsion copolymer composition.
• the improved composition can be used as a coating for rubber articles.
• "powder-free” mean that the composition has been manufactured to eliminate most, if not all, powder.
• the improved coating composition is prepared by copolymerization of a reactive silicone acrylate, an alkyl acrylate and a hard monomer. Such compositions are known in the art. However, an improved composition is obtained when a silicone emulsion is added to the composition.
• the composition can contain water-soluble surfactants, such as non-ionic surfactants.
• the surfactants can be used to stabilize the composition so that coagulating metal salts can be added to the composition without causing the composition to destabilize.
• the composition is capable of coagulating latex once dipped and dried on a former.
• the improved composition of this invention can be used as a coating for rubber articles. When used as a coating for rubber articles, the composition can be coated on the inside and outside of the rubber article. The coating provides good dry donnability and some good wet donnability.
• the present invention comprises a powder-free acrylic based emulsion copolymer coating composition which can be used as a coating for rubber articles.
• the improvement in the coating over other coatings in the prior art is the addition of a silicone emulsion to the composition.
• Acrylic based emulsion copolymer compositions are known in the art.
• the coating composition can prepared by copolymerizing a reactive silicone acrylate, an alkyl acrylate and a ⁇ hard monomer. It is preferred that such copolymerization take place in the form of emulsions.
• Methods for preparing emulsions are well known in the art. However, a better and more improved coating is obtained when a silicone emulsion is added to the composition. Compositions such as those described in U.S.
• Patent 5,234,736, hereby incorporated by reference, can be modified to provide good coatings for rubber articles.
• This composition comprises a "reactive silicone acrylate polymer.” What is meant by a “reactive silicone acrylate polymer” is polymeric siloxanes and silicones which display an acrylate functionality including but not limited to acrylate polysiloxanes. The acrylate functionality is greater than 1.
• Examples of the multifunctional silicone acrylates that can be used include Tego ® silicone acrylate RC 149, 300, 450, 710, 720, and 802 and ZMR1395 manufactured and sold be Goldschmidt Chemical Corporation of Hopewell, VA, which polymers are linear dimethylpolysiloxanes with acrylate functionality and a molecular weight between 1000 and 20,000 g/mol and include dimethylpolysiloxanes with pentaertyritoltriacrylate.
• the composition may contain less than about 10% by weight of the reactive silicone acrylate polymer.
• the rest of the composition comprises at least one alkyl acrylate and at least one hard monomer.
• the alkyl acrylate that can be used in the composition can have the formula:
• R is hydrogen or a methyl group and R x represents, when R is methyl, a primary or secondary alkyl group of 5 to 18 carbon atoms, or when R is hydrogen, an alkyl group not over 18 carbon atoms, or better, of 2 to 12 carbon atoms.
• Typical compounds within the above definition are methyl acrylate, ethyl acrylate, propyl acrylate, isopropyl acrylate, butyl acrylate, isobutyl acrylate, sec.
• the amount of alkyl acrylate that can be employed in the composition is 10 to 90% by weight.
• the balance of the composition comprises of a hard monomer.
• hard monomer what is meant is monomers having a glass transition temperature (Tg) greater than 0°C.
• hard monomers that can be used in this composition styrene, methacrylate, ethyl acrylate, alkyl methacrylates having alkyl groups of not over four carbon atoms, also tert. - amyl methacrylate, tert . -butyl or tert. -amyl acrylate, cyclohexyl acrylate or methacrylate, acrylonitrile or methacrylonitrile, and unsaturated carboxylic acids.
• the resulting composition has a glass transition temperature above 35°C.
• additives such as free radical catalysts, chain transfer agents, antioxidants, etc. can be employed as needed.
• the composition contain metal coagulating salts capable of coagulating latex.
• the amount of metal salt added to the composition is at least 5-25% and preferably 10-20% by weight of coagulating salts.
• These coagulating salts are most commonly inorganic salts of mineral acids such as water soluble alkaline earth salts of hydrochloric, sulfuric or nitric acids.
• salts such as calcium chloride or calcium nitrate provide satisfactory coagulation of most rubber latices. Salts of zinc and aluminum may also be used.
• the salts when added to the coating composition can in certain instances cause destabilization.
• a stabilizing amount of a water soluble surfactant preferably a non-ionic surfactant
• a water soluble surfactant preferably a non-ionic surfactant
• the amount and type of surfactant can only be determined by experimentation since the components of the composition and particular coagulant salt will vary. Usually not more than a few percent of the stabilizer is necessary e.g. about from 0.1% to about 3% by weight. It will be understood that when the coating composition is used to form a coating on the inside of the finished article such as a glove it is not necessary nor desirable that it contain a coagulating salt. In a similar fashion it not necessary that the same latex used as the former mold release coating be used in the formation of the donning coating.
• the thickness of the coatings applied to the former or to the formed article will vary and can be optimized by routine experimentation.
• the thickness of the former release coating need not necessarily be the same thickness as a donning coating.
• the thickness of the coatings should not be not be greater than 20% the thickness of the coating of the rubber latex article.
• coatings as thin as 200 microns up to coatings of several mils may be used.
• a preferred method of combining the silicone resin with the composition is to use silicone emulsions which contain in emulsion form polymers such as polydimethylsiloxane polymers.
• silicone emulsions which contain in emulsion form polymers such as polydimethylsiloxane polymers.
• One such emulsion is sold by Dow Corning under the trade designation, Dow Corning Emulsion 365. While the amount of silicone resin in a dry weight basis may range between 0.001 to 3% by weight, typically, 0.1 to 2.5% will give good results. Amounts as great as 5% may be used, but too much may produce adverse effects. These emulsions may require modifications to render them compatible and stable when they are blended with the composition.
• the silicone emulsion can comprise silicone monomers having vinyl unsaturation which when mixed with silicone hydride containing crosslinkers is cured by a Group VIII metal catalyst, preferably a platinum catalyst.
• a silicone emulsion such as 400-E, available from Wacker Chemicals USA, Norwalk, CT, which contains an emulsified vinyl oil, a platinum catalyst, and a platinum inhibitor can be used.
• the emulsion can also contain reactive surfactants.
• the preferred vinyl-addition silicone emulsions are mixtures of reactive vinyl silicone polymers of the formula:
• Vinyl-addition silicone systems react by thermally induced addition-cure (hydrosilations between polydimethyl-hydrogen siloxane crosslinkers and reactive vinyl-functional silicone polymers) to furnish a cured silicone release composition.
• the vinyl-functional silicone molecules are polydimethylsiloxanes, where some of the methyl groups have been substituted with vinyl groups or other alkyl groups containing vinyl unsaturation, i.e. the reaction takes place between a vinyl substituted polydimethylsiloxane and polydimethylhydrogen siloxane.
• the whole hydrosiliation is catalyzed by silicone soluble complex compounds of Group VIII transition metals, particularly platinum.
• a small amount of inhibitor is added to prevent premature reaction between the silicone hydride and vinyl silicone groups following mixing of the existing components, before deposition onto the substrate. The inhibitor is removed or made ineffective during the thermal curing process.
• a suitable silicone emulsion system showing the practice of this invention can be obtained from Dow Corning, Rhone- Poulenc, and Wacker-Chemicals, USA, a division of Wacker-Chemie of Germany.
• the coating composition of this invention is made without the use of powder.
• the former is dipped or immersed in the composition to form a film or first layer and is then withdrawn. After the former is withdrawn from the composition, the first layer is allowed to stand and dry or is dried in an oven at 70°C for about 3 minutes to form a coherent film or layer. Once dried, the first layer is capable of inducing conventional coagulation when dipped or immersed into a latex compound. After the formation of the first layer, the former is then dipped into a latex compound to form a second layer.
• the latex compound can be any coagulatable natural or synthetic latex compounds, coagulatable natural or synthetic rubber latices or styrenic block copolymer dispersions known in the art.
• Conventional formulations for the preparation of latex are well known in the art and those skilled in the art are readily able to vary the formulations and conditions of curing and the like to suit the particular latex being used as well as the final article desired.
• Precured or partially cured latex can be used; however, if non-cured' latex is used, it must be cured after forming. Additionally, the latex may contain conventional compounding ingredients commonly utilized. Specific examples are provided in U.S. Patent 3,411,982, hereby incorporated by reference.
• the dried film When the former is immersed into the latex compound, the dried film induces coagulation of the latex to produce a uniform coagulated deposit of the latex on the former.
• the length of time the former is immersed in the latex determines the wall thickness of the article. The longer the dwell time period, the greater the wall thickness of the article, and vice versa.
• Articles produced according to the method of this invention typically have a thickness of between 4 to 15 mils .
• the former is removed from the latex with a coating of gelled latex adhering to it.
• the former is placed in a water bath to leach out water soluble components such as proteins, electrolytes, etc.
• the temperature of the water bath is between 49-60°C.
• the second layer maybe dried or coated with a lubricating polymer. If dried, then the first and second layers are cured.
• the term "curing” also includes “fusing” or “fusion” as some types of polymers require fusing instead of curing.
• thermoplastic elastomers such as the copolymers poly(styrene-b-isoprene-b-styrene) (SIS) , poly(styrene-b-butadiene-b-styrene) (SBS) , and poly(styrene-b-ethylene propylene-b-styrene) (SEPS) require fusing.
• SIS poly(styrene-b-isoprene-b-styrene)
• SBS poly(styrene-b-butadiene-b-styrene)
• SEPS poly(styrene-b-ethylene propylene-b-styrene)
• compositions When the composition is used as article coatings can be applied either before the drying of the second layer, after the drying of the second layer but before curing, or after curing. When applied, it will add additional layers to the already multi-layered article.
• the acrylic ester latex After the acrylic ester latex is coated to the article, it is allowed to stand and dry or is dried in an oven.
• the conditions required for drying the lubricating polymer in an oven vary based on the type of lubricating polymer employed. If the acrylic ester polymer is added to the article prior to curing, the polymer may be dried and the article cured in one step. If the polymer is applied after the article is cured, then it must be dried.
• the molds used are in a variety of sizes and shapes corresponding to the various hand sizes for which the gloves are intended.
• the preferred mold is a contoured mold having a textured to highly polished ceramic or porcelain surface or one having a fluorocarbon coating, however, other molds such as glass, hard woods, and plastic can also be used. Gloves produced using this improved composition are easily removed from a former are not tacky, exhibit good donning characteristics, and are powder-free.
• a coagulant emulsion was prepared by mixing 200 grams of an acrylic emulsion, IL-93-10-19, available from Avery Dennison Corporation, Pasadena, California, containing a reactive silicone acrylate an alkyl acrylate and a hard-monomer with 10 grams of a silicone emulsion.
• the silicone emulsion comprises 34.3 grams of 400 E, which is a vinyl oil that uses a vinyl oil and platinum catalyst and a platinum inhibitor available from Wacker Chemicals USA, Inc., Norwalk, CT, and 8.14 g of V-20, a silicon hydride cross-linker also available from Wacker Chemicals USA, Inc.
• 40 grams of calcium nitrate and 40 grams of water were added.
• a ceramic mold was warmed to 80°C and dripped for about 4 seconds into the above emulsion and after drying dipped into the latex compound. The mold was then dipped into a warm water bath and leached. After leaching the mold is dipped into the acrylic emulsion (IL-93-10-19) without coagulant. The formed product is then cured at 138°C for 10 minutes and removed from the former.

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• Chemical & Material Sciences (AREA)
• Health & Medical Sciences (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Medicinal Chemistry (AREA)
• Polymers & Plastics (AREA)
• Organic Chemistry (AREA)
• Paints Or Removers (AREA)
• Gloves (AREA)

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• 1996
  • 1996-05-03 JP JP8536484A patent/JPH10508899A/ja active Pending
  • 1996-05-03 WO PCT/US1996/006317 patent/WO1996038487A1/en not_active Application Discontinuation
  • 1996-05-03 EP EP96913351A patent/EP0773966A1/de not_active Withdrawn

Non-Patent Citations (1)

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