Method of making latex articles

Abstract: There are described methods of forming a chemical barrier against the transmission of disease-causing microbes and other harmful agents through a membrane such as latex. In the principal method, a mold or former is coated with a solution of a biocide/coagulant which is dried, and then the former is dipped into liquid latex. In an alternative method, the mold or former receives a preliminary coating of liquid latex which is allowed to gel before application of the biocide/coagulant and subsequent latex coating. The entire coating on the former is then cured to form the final latex article, such as a glove or condom.

Description: This invention relates to the manufacture of latex articles incorporating a biocidal material for preventing the transmission and dissemination of disease and is especially applicable to the manufacture of such articles as gloves and condoms. Latex has long been used for the manufacture of gloves and condoms for the purpose of inhibiting the transmission of disease-producing microbes and other harmful agents. Compare FR-A-2 663 035. Both the chemical inertness and the physical density of cured latex make it difficult for molecules and microbes to pass through the structure of the latex material. Nevertheless, latex materials are known to possess imperfections in the form of pits, pores and holes which can facilitate the transmission of such microbes and harmful agents through the latex material. The present invention seeks to provide a procedure by means of which it is possible to make a chemical barrier against the transmission of such microbes and other harmful agents through a membrane such as latex. The present invention now provides a method of forming a chemical barrier against the transmission of disease-causing microbes and other harmful agents through a membrane such as latex. In the method of the invention, a mold or former is coated with a biocide/coagulant which is dried, then the former is dipped into liquid latex. In an alternative procedure, the former is initially dipped into liquid latex which is allowed to gel before being dipped into the biocide/coagulant. The entire coating on the former is then cured. Alternatively, the biocide may be sprayed or otherwise applied onto the former or the gelled latex. The present invention concerns the forming of a chemical barrier against disease-causing microbes and other harmful agents through a membrane fashioned from natural latex or from a synthetic latex material such as those known as natural skin, solvent cast membranes, elastomers, and polymers formed by curing the material from a liquid state. For convenience, the preferred aspects of the invention will be described with reference to a latex material. The latex material may be fashioned as a glove, condom, diaphragm, slipper, overshoe, sterile band, catheter, tubing, diaphragm, drape, gut opening, mouthpiece, baby nipple, intragastric nasal tube, nasal gastric tube, kidney shunt, rubber dam for teeth, plastic brace for teeth, sub-clavian vein or artery shunt, colostomy bag or any other product. Normally such latex products will be adapted for use in juxtaposition to a person's or animal's skin. As used in the context of the present application, the term "biocide" means a substance or material which renders the disease-producing characteristic or harm-causing characteristic of a microbe or harmful agent ineffective substantially upon contact or shortly after contact of the microbe or harmful agent with the biocide. Examples of suitable biocides are dextran sulphate, nonoxynol-9, benzalkonium, betadyne, gentian violet, acriflavine and acridine dyes, mercurochrome, silver salts and an extract of blue green algae. Other examples of suitable biocides are set out in the list below. Latex products, such as latex gloves and condoms, are conventionally formed by either a single dip or a double dip process. In these processes, a mold or former in the shape of the desired latex product is initially covered with a chemical coagulant, which allows a relatively thick, uniform, continuous layer of latex to be deposited on the former. The coagulant is dried on the former, and then the former is dipped into a vat of liquid latex for an appropriate period of time, whereby a film of latex is picked up on the surface of the former. The latex is allowed to wet gel into a sticky or tacky state and while in the gel state, is leached in a warm water rinse or bath. The warm water removes the coagulant as well as any residual ammonia or potassium hydroxide which might be present. In order to increase the thickness of latex, the process may be repeated so that a second film of latex is built up integrally over the first layer of latex. Usually the second layer is less thick than the first layer. In accordance with the invention, the coagulant is selected so as to have biocidal properties so that the final latex product incorporates a biocide barrier. The method of the invention permits such latex products to be made by the general procedure described above and by the alternative procedure of initially applying a first liquid latex coating to the mold or former and then applying the biocide/coagulant to that first liquid latex coating before applying one or more further liquid latex coatings over the biocide/coagulant. A biocide barrier can be incorporated into a latex product in the above manner, as follows. After the first dip of the former into the liquid latex and after the preferred warm water leach in a conventional manner, the former with the liquid latex in a wet gel state is dipped into a 0.10 to 5% by weight solution of gentian violet, for example a 0.33% by weight solution in water. The biocide solution coats the liquid latex. Alternatively, the biocide solution may be sprayed or otherwise applied to the wet gel latex. The biocide solution coating is then dried. Thereafter, the former is dipped again into a vat of liquid latex, may be leached again, and then the entire coating on the former is cured by drying. It appears that the biocide solution acts as a coagulant, and causes the second layer of latex to be relatively thicker than is normally achieved without any biocide solution. The amount of biocide solution applied either to the former or to the initial latex coating on the former is preferably such that the weight ratio of that biocide solution coating to the subsequent latex coating is 0.05 to 0.3. A solution of 1.5% by weight of for example, gentian violet in water has also been used in this process, with slightly less desirable uniformity in thickness of the coatings. Nevertheless, it is believed that concentrations of up to about 5% by weight of gentian violet in water or in water and alcohol with or without other cosolvents can be advantageously used in the process. It has been observed that the maximum amount of biocide solution picked-up by the wet gel latex coating the former is about 0.2 grams of solution per gram of latex. It is believed that the biocide is bonded to and is permanently diffused within the surface of the latex, thereby substantially filling the pores and other imperfections of the latex. The following biocides are believed to be equally suitable to those described above for use in the invention: halogen and halogen compounds - chlorine and iodine; phenolic compounds; alcohols; oxidants; chlorhexidine; nitrogen compounds; surface active agents, such as quaternary ammonium compounds, acid anionic compounds, amphoteric compounds, heavy metals and dyes, e.g. crystal violet; antibiotics; HC BLUE NO. 2 (N 1 ,N 4 ,N 4 ,-(2-hydroxyethyl)-2-nitro-p-phenylene-diamine); NONOXYNOL-2 (polyoxyethylene (2) nonyl phenyl ether); NONOXYNOL-4 and -8; D & C RED NO. 22 (eosine YS); D & C RED NO. 37 (rhodamine B-stearate); D & C RED NO. 37 CALCIUM LAKE (rhodamine B stearate solvent); and the following products listed according to their recommended or generally accepted biocidal applications:- Antimicrobial Soaps : Cloflucarban Para-chloro-mein-xylenof Povidone-iodine complex 1.5 percent phenol or less aqueous/alcoholic Triclocarbon Tricloean Health-care Peronnel Handwash : Benzalkonium chloride Benzethonium chloride Clofluearban Hexylesorinal Iodine complexed with phophate eater of alkyaryloxy polyethlene glycol Methyl-benzethonium chloride Nonyl phenoxypoly (ethyleneoxy) ethanol-iodine Para-chloro-meta-xylenol Povidene-iodine complex 1.5 percent phenol or less aqueous/alcoholic Poloxamer-iodine complex Tricloearban 1 Undecoylium chloride-iodine complex Patient preoperative skin preparation Bonzalkonium chloride Benzethonium chloride Hexylresorcinoi Iodine complexed with phosphate ester of alkylaryloxy polyethylene glycol Methylbenxethonium chloride Nonyl phenoxypoly (ethyleneoxy) ethanoilodine Para-thloro-meta-xylenol 1.5 percent phenol or less aqueous/alcoholic Poloxamer-iodine complex Povidene-iodine complex Undecoylium chloride-iodine complex Skin antiseptic Benzalkonium chloride Benzathonium chloride Hexylresorcinoi Iodine complexed with phosphate ester of alkylaryloxy polyethylene glycol Iodine tincture Methyl-bonzethonium chloride Nonyl phenoxypoly (ethylencoxy) ethanoliodine Para-chloro-meta-xylenol 1.5 percent phenol or less aqueous/alcoholic Poloxamer-iodine complex Povidene-iodine complex Triclosan Triple Dye Undecoylium chloride-iodine complex Skin wound cleanser Cloflutarban 1 Iodine complexed with phosphate ester of alkylaryloxy polyethylene glycol Iodine tincture Nonyl phenoxypoly (ethyleneoxy) ethanoliodine Para-chloro-meta-xylenol 1.5 percent phenol or less aqueous/alcoholic Poloxamer-iodine complex Povidene-iodine complex Tricloearban 1 Triclosan Undecoylium chloride-iodine complex Skin wound protectant Benzalkonium chloride Benzathonium chloride Hexylresorcinoi Iodine complexed with phosphate ester of alkylaryloxy polyethylene glycol Iodine tincture Methyl-bonzethonium chloride Nonyl phenoxypoly (ethylencoxy) ethanoliodine Para-chloro-meta-xylenol

Claims: A method of making a latex article having a biocide barrier, comprising the steps of: applying onto a former a first coating consisting essentially of liquid latex and free of biocide; applying to the first coating of liquid latex a second coating consisting essentially of a biocide effective as a coagulant for liquid latex; and applying to said second coating a third coating consisting essentially of liquid latex and free of biocide. The method according to claim 1, wherein the third coating is thicker than the first coating. The method according to claim 1 or 2, wherein the first coating is leached with water prior to application of the second coating. The method according to any of claims 1 to 3, wherein the second coating is dried before applying the third coating. The method according to any of claims 1 to 4, wherein said first coating is applied by dipping the former into liquid latex. The method according to any of claims 1 to 5, wherein the second coating is applied onto the first coating when the latex in the first coating is in a wet gel state. The method according to any of claims 1 to 6, wherein the second coating is applied by spraying a biocide solution. The method according to any of claims 1 to 6, wherein said second coating is applied by dipping the former into a biocide solution. The method according to any of claims 1 to 8, wherein the biocide is applied as a solution having a concentration of 0.10 to 5 percent by weight. The method according to any of claims 1 to 9, wherein said third coating is applied by dipping the former in a vat of liquid latex. The method according to any of claims 1 to 10, wherein the biocide is selected from chlorhexidine, dextran sulfate, triclosan, benzalkonium, betadyne, gentian violet, acriflavine and acridine dyes, mercurochrome, silver salts, and an extract of blue-green algae. The method according to any of claims 1 to 11, wherein the weight ration of the biocide solution to the first latex coating is from 0.05 to 0.3. The method according to any of claims 1 to 12, wherein the weight ratio of the biocide solution in the second coating to the latex applied in the third coating is between 0.05 and 0.3. The method according to any of claims 1 to 13, wherein the biocide is bonded to and is permanently diffused within the surface of the latex membrane.

Inventors: BECK ROBIN THILL, PLUNKETT JERRY D, SMITH CLAYTON S, SOLOMONS CLIVE C, BECK, ROBIN THILL, PLUNKETT, JERRY D., SMITH, CLAYTON S., SOLOMONS, CLIVE C.
Applicants: BECK ROBIN THILL, BECK, ROBIN THILL
Application year: 1992
Main classification: B29C41
IPC codes: A61L31, A61L2, A61L33, A61L29, A61F6, B29C41, B29K105, C08C1, B32B25, B29L9, B32B9