Title of Invention

A PROCESS FOR THE PREPARATION OF A POLYMER COATED POWDER FREE FLEXIBLE RUBBER ARTICLE

Abstract In accordance with the present invention, there is provided a coated flexible rubber article, such as but not limited to surgeon's glove & examination gloves made out of natural or synthetic rubber. The present invention is related to a two-side treated formed rubber article having a polymer coating on the outer and the inner surface; or having a polymer coating on the inside and a chlorinated outer surface. It is also related to a process for making gloves using a polymer as an inner coating to provide better donning properties and an outer polymer coating or a chlorination process to provide a better grip of the glove outside surface. The rubber article is thus formed as a powder-free glove with better donning and grip. The polymer coating can be stretched with the rubber without flaking.
Full Text

DESCRIPTION
The present invention relates to a two-side treated rubber article having either a polymer coated surface or a chlorinated surface and having a Polymer coated inner surface. The invention is also related to a process for forming such an article, and in particular forming a latex examination and surgical glove.
BACKGROUND OF THE INVENTION
Rubber articles are elastomeric materials having low glass transition temperatures (Tg). Surfaces of the low Tg articles tend to stick together. Elastomeric surface of articles, in general, exhibit poor lubricity with respect to a dry surface, such as dry skin or other mammalian tissue. These properties are due to surface friction. A high coefficient of friction is a distinct disadvantage in those applications where an elastomeric surface must slide on another surface, such as in the donning of gloves over skin. This is particularly important in the use of medical gloves, such as examination gloves and surgeon's glove. These gloves are relatively close fitting in order to provide sensitivity. The elastomeric materials useful in such applications must exhibit enhanced lubricity with respect to dry surfaces ("dry slip"), and the requisite mechanical properties. The prior art has attempted various ways to produce powder free gloves which satisfy these requirements.
In particular, in a rubber or latex glove, the inside of the glove must allow for good donning, while the outside of the glove (which is in contact with a former during manufacturing) must be able to be easily released from the former, and must not stick to other gloves when packaged (must have good anti-blocking properties). Both of these problems have been solved in the past by coating the inside and outside of a glove with a powder, such as starch, or calcium carbonate.
The powder coating is a known nuisance, as loose powder can become airborne. The powder tends to absorb proteins found in natural rubber latex and the powder is easily dislodged during donning and use, contaminating the surrounding environment and causing allergies and other negative effects. Further, the protein/powder complex serves as food source for bacteria, allowing them to proliferate. Recently, there has been a growing demand for powder-free natural and synthetic rubber gloves, which do not use loose powder for donning and former release.
One prior approach is to halogenate the surface of rubber gloves with chlorine or bromine to make it slippery, i.e., reducing tackiness and decreasing the coefficient of friction of the rubber gloves. One popular alternative to a powdered glove is a powder-free glove using chlorination of both the inner and outer surfaces to reduce the

tack and friction of the rubber. In the case of chlorine as the halogen, the prior art discloses the production and use of chlorinated water to treat the rubber gloves. An additional advantage of this process is a reduction in the protein level of the latex. Chlorination of both surfaces of a glove is a very labour intensive process. Such methods include (1) direct injection of chlorine gas into the water mixture, (2) mixing high density bleaching powder and aluminium chloride in water, (3) brine electrolysis to produce chlorinated water, and (4) acidified bleach. See for example U.S. Pat. No. 3,411,982 (Kavalir), U.S. Pat. No. 3,740,262 (Agostinelli), U.S. Pat. No. 3,992,221 (Homsy, et al; treating other surface with chlorine gas), U.S. Pat. No. 4,597,108 (Momose), and U.S. Pat. No. 4,851,266 (Momose). A disadvantage is that the chlorination process makes the rubber less pliant, and reduces the shelf life of the glove. Halogens are known to degrade rubber and hence the process tends to be inconsistent and needs a good control over the process. The process also imparts a characteristic chlorine smell to the product '
There are other prior rubber articles having a slip layer bonded to the inner surface of such gloves. Examples of gloves which have an inner layer of elastomeric material with particulate lubricant imbedded therein are disclosed in U.S. Pat. No.4, 070,713 (Stockum), U.S. Pat. No. 4,143,109 (Stockum), U.S. Pat. No.5, 284,607 (Chen), and U.S. Pat. No.5, 395,666 (Brindle; together with a surfactant, but ionic surfactants are not recommended), and which disclose surgeon's gloves with various polymeric slip coatings bonded to the inner surface thereof are U.S. Pat. Nos. 3,286,011 and 3,411,982 (both to Kavalir et al.; an inner layer of a rubber/resin combination, wherein the resin may be acrylic-type resins, allowing elongation values of 200% to 700%); U.S. Pat. No. 3,813,695 (Podell, et al.; an inner layer of hydrophilic plastic material, e.g., hydrogel polymer), U.S. Pat. No. 3,856,561 (Esemplare, et al.; an inner layer of a copolymer of vinyl chloride or vinylidene chloride and an alkyl acrylate, e.g., copolymer of vinyl chloride or vinylidene chloride with butyl acrylate and acrylic acid), U.S. Pat. No. 4,302,852 (Joung; e.g., inner layer of silicone), U.S. Pat. No. 4,482,577 (Goldstein, et al.; elastomeric article is cleaned, immersed in a concentrated solution of a strong acid, washed, dipped in a solution of an uncured hydrophilic polymer and then cured; articles are described as stretchable to 700%), U.S. Pat. No. 4,499,154 (James, et al.; article is pre-treated in a dilute acid solution prior to applying inner layer; uses specific hydrogel polymers as the inner layer which is then treated with a cationic surfactant or fatty amine) and U.S. Pat. No.4,575,476 (Podell, et al.; hydrogel polymer inner layer treated with cationic, anionic or non-ionic surfactant).
Some of the latter-type gloves experience delamination of layers or produce a "cobblestoning" effect when stretched, for example, when the gloves are donned. Prior gloves have been made to address this problem. According to U.S. Pat. No. 5,570,475, prior attempts to improve resistance to delamination have included treatment of the natural or synthetic elastomeric base material by an acid priming step and a neutralizing step prior to the polymer coating step, citing U.S. Pat. No. 4,499,154 (noted above). According to U.S. Pat. No. 4,548,844 (Podell et al.), a trivalent cationic salt, e.g., aluminium salt, may be applied to the elastomeric article prior to or simultaneously with the application of the hydrophilic hydrogel polymer so

as to provide for improved adhesion of the polymer to the article after curing. Other gloves utilise certain types of polymers as the inner layer to avoid or minimize delamination when the article is stretched or flexed. For example, U.S. Pat. No. 4,082,862 (Esemplare et al.) is identified as an improvement over U.S. Pat. No. 3,856,561 (Esemplare et al.) to avoid the "cobblestoning" effect observed when the elastomeric article is stretched to a large extent, e.g., over 450%. Therein, a blend of polymers each with specific required properties is used. As another example, U.S. Pat. No. 5,570,475 (Nile et al.) discloses copolymers of styrene or ethylene with half esters of maleic acid.
Another method for producing a powder-free glove is the use of polymer coatings. Several types of polymer coatings have been developed, primarily based on polyurethanes: U.S. Pat. No. 5,088,125 discloses gloves modified by an ionic polyurethane; U.S. Pat No, 5,272,771 discloses gloves modified by an ionic polyurethane containing fully reacted isocyanate groups; and U.S. Pat. No.5,534, 350 discloses gloves in which the outer glove coating contains a polyurethane dispersion and the inside glove coating contains a polyurethane containing a silicone emulsion.
Other coatings which have been developed include emulsion copolymers, particularly core-shell, containing low surface energy monomers and hard monomers as disclosed in U.S. Pat. Nos. 5,691,069 and 5,700,585; or containing two monomers selected from styrene, methyl or butyl acrylates, methacrylic or acrylic acid and a silicon oligomer, with glass transition temperatures of less than O.degree. C. and from 0 to 100 degree. C. respectively as disclosed in U.S. Pat. No. 5,712,346. These sequential emulsion polymerizations lead to substantially linear copolymers. Copending U.S. patent application Ser. No. 09/400,488 describes the use of star polymers as coating for latex gloves. Copending U.S. patent applications Ser. Nos. 09/663,468 and 09/882,222 describes polymer coating and polymer former release compositions useful for inner and outer glove coatings respectively, and are incorporated herein.
It has now been found that a process for two-side treated rubber articles, involving chlorination or polymer coating of the outer surface and a polymer coated inner surface, advantageously combines the positive features of both technologies to produce a powder-free glove.
The foregoing differs from the present invention.
SUMMARY OF THE INVENTION
The present invention is directed to a process of producing a two-sided treated rubber article having a polymer coated inner surface, and a chlorinated or polymer coated outer surface.
The invention is also directed to a process for making a glove comprising

a] immersing a glove former in a coagulant solution comprising of a coagulant, a wetting agent and a release agent.
b] immersing the coated former into a rubber latex to coat the former with said latex;
c] hot water leaching of the latex gel
d] immersing the partially dried latex gel into a bath of formulated Polymer coating solution
e] partially drying the polymer coating on the leached latex gel
f] curing the Polymer coating along with the latex gel
g] leaching the cured latex film in hot water h] stripping the gloves off the formers
i] post processing the gloves in a tumble drier
j] powder free processing involving polymer coating of the outer surface k] a finish coat on the outer surface of the glove using a non-ionic slip agent The invention is further directed to a process for making a glove comprising
a] immersing a glove former in a coagulant solution comprising of a coagulant, a wetting agent and a release agent.
b] immersing the coated former into a rubber latex to coat the former with said latex;
c] hot water leaching of the latex gel
d] immersing the partially dried latex gel into a bath of formulated Polymer coating solution
e] partially drying the polymer coating on the leached latex gel
f] curing the Polymer coating along with the latex gel
g] leaching the cured latex film in hot water h] stripping the gloves off the formers
i] post processing the gloves in a tumble drier

j] powder free processing involving chlorination of the outer surface
k] a finish coat on the outer surface of the glove using a non-ionic slip agent
DETAILED DESCRIPTION OF THE INVENTION
The present invention is directed to a process of producing a two-sided treated rubber article having a polymer coating on the inner surface; and a chlorinated or polymer coated outer surface. The invention envisages flexible elastomeric articles including those adapted for use in partial or total contact with mammalian tissue, such as surgical, examination and dental gloves, condoms, bandages, catheters, sheathes and sheath-type incontinence devices and other film articles.
A rubber article, as used herein, refers to an article made of a natural or synthetic, low-Tg, elastomeric polymer or mixture of polymers. Examples of such polymeric materials include, but are not limited to, butyl rubber, natural latex rubber, polyvinyl chloride, neoprene, nitrile, viton, styrene butadiene copolymers, polyurethanes, or interpenetrating polymer network emulsion polymers, or combinations of these.
The polymer coating on the inner surface of the rubber article serves as a coating that facilitates easy donning. The polymer of the invention is a composite mixture of polymers of the type ethanol homopolymer, a styrenic acrylic emulsion, a biopolymer and a suitable non-ionic surfactant. For ease of use in a glove manufacturing process, the polymer should be water-borne.
The polymer used as the inner and outer coating of the rubber article may be formulated with other optional ingredients, such as dispersants, surfactants, microspheres, and rheology modifiers. A rheology modifier is optionally present in the polymer composition.
The inside polymer composition may also contain other additives known in the art, such as biocides, and antifoaming agents.
The polymer composition for the inner and outer surface of a rubber article is made by combining each of the ingredients to form an aqueous dispersion, by means known in the art.
Chlorination of the outer surface of the rubber article can be done by any means known in the art, including immersion in an aqueous chlorine solution, or a solution which will release electrophilic chlorine over time. An aqueous chlorine solution, useful in the present invention contains from 400 to 1500 ppm of chlorine. This solution can be made using a bleach solution containing sodium hypochlorite, and adding hydrochloric acid immediately prior to use.
Chlorination of gloves may occur in an off-line process processed in suitable batches.

A process for forming any two-side treated rubber article, will be exemplified for a glove, and in particular a natural latex glove.
The process for forming any two-side treated rubber article, will be exemplified for a glove, and in particular a natural latex glove.
The process for forming a latex glove of the present invention consists of these basic steps:
a] immersing clean glove former in a coagulant solution, to produce a thin film of coagulant onto the former
b] immersing the coated former into a rubber latex to coat the former with said latex;
c] hot water leaching of the latex gel
d] immersing the partially dried latex gel into a bath of formulated Polymer coating solution
e] partially drying the polymer coating on the leached latex gel
f] curing the Polymer coating along with the latex gel
g] leaching the cured latex film in hot water h] stripping the gloves off the formers
i] post processing the gloves in a tumble drier
j] powderfree processing involving either chlorination or polymer coating
The polymeric inner coating is applied to the surface of the latex gel, normally by immersion of the former into a tank containing aqueous polymer dispersion. The formers may be of any material known in the art, including but not limited to ceramics, glass, and stainless steel. Useful coagulants include, but are not limited to, calcium nitrate and calcium chloride.
After drying of the formers, they are coated with a coagulant solution containing a coagulant, a release agent and a wetting agent. The release agent used may be a carbonate and the wetting used may be a polyethylene oxide condensate. The formers coated with the coagulant can be used to prepare a glove by methods known in the art. For example, the coated former is immersed in a natural or synthetic rubber latex for a time sufficient for the rubber to coagulate and form a rubber coating of the desired thickness. The rubber coating on the former forms a latex gel, which later cures to

form a glove. The latex gel then may be water leached to remove impurities from the rubber.
The formed glove is then dipped in a solution containing suitably formulated Polymer coating solution. The level of the tank and the level of dip of the latex gel is adjusted to get optimal result. The dipped latex gel is then oven cured, and then again leached in hot water to remove residual chemical and proteins. The glove is then dried and stripped off the formers. The glove stripping could be done manually or mechanically by using a pneumatic air stripping mechanism. The gloves are inverted during stripping and the polymer coating on the glove becomes on the inner surface of the glove. The gloves are tumble dried to remove excess moisture and residuals. The tumbling also equilibrates cure.
The gloves are then post-processed to form a powder free glove by any of the following methods.
Method 1, subjects the tumbled and dried polymer coated gloves to an off-line method of Polymer coating. This process coats the outside of the glove with the Polymer coating. The Polymer composition is the same as that used in the in-line method. The gloves are first washed in water to remove residual proteins and other debris from the gloves. The washed gloves are then tumbled in the Polymer coating solution to coat the outside surface uniformly. The wet gloves are then dripped off the extra polymer solution and then dried. The dried gloves are then treated with a finish coat of a non-ionic slip agent. This imparts the glove an anti-block property and helps to avoid sticking together of the glove.
Method 2, subjects the tumbled and dried polymer coated gloves to an off-line method of Chlorination. This process modifies the outside surface of the glove. The gloves are loaded into an automatic chlorinator and first washed with water to remove residuals on the glove. The process is PLC controlled and the programs are validated so that there is total control over the process. The gloves are treated with chlorine water produced in-situ by injecting chlorine gas into water in the closed container. The gloves are tumbled in the chlorine water for the required time and a ppm level of 400 to 1500 is maintained during tumbling. The exact quantity of chlorine is measured during each cycle and is kept constant for consistency. The excess chlorine is neutralized with Sodium thiosulphate and ammonia and then rinsed in water thoroughly to remove any left over chemical residues. The gloves are then removed from the chlorinator after the process cycle. The gloves are dried in a tumble drier and then coated with a finish coat of a non-ionic slip agent.
Rubber articles formed using the process of the invention include gloves, prophylactics, catheters, tires, swimming caps, balloons, tubing, and sheeting. A particularly suitable end use application is as a release composition in the production of latex gloves, including surgeons' gloves, physicians' examining gloves, and workers' gloves, more particularly powder-free latex gloves.

EXAMPLES
The following examples are presented to further illustrate and explain the present invention and should not be taken as limiting in any regard. In the given examples, one side of the glove is Polymer coated on-line by dipping in a tank containing a suitably formulated Polymer coating solution. The gloves are then cured and stripped off the formers. The other side is either Polymer coated or chlorinated by an off-line method.
Example 1
In this example the gloves were Polymer coated to modify the outside surface of the glove. The polymer coating process of the elastomeric articles was performed using the steps of;
a] placing the elastomeric articles into a suitable corrosion-resistant tumble washer,
b] rinsing all particulate matter from the polymer coated elastomeric articles with water,
c] adding about 60L of water into the container and adding polymer coating solution into it so as to make the solution to about 3% total solids.
d] tumbling the glove in the polymer solution for about twenty five minutes
e] repeated rinsing of the gloves in de-ionized water to remove all the residuals
f] removal of gloves from the tumbler and dripping to remove excess Polymer coating solution
g] tumbling the gloves in a dryer until dry
h] coating the dried gloves with a suitable slip agent
Example 2
In this example the gloves were chlorinated to modify the outside surface of the glove. Chlorination of the elastomeric articles was performed using the steps of;
a] rinsing all particulate matter from the polymer coated elastomeric articles with water,
b] placing the elastomeric articles into a suitable corrosion-resistant container,
c] adding about 5000Lof water in to th6 container and injecting chlorine gas into it so as to provide a chlorine level ranging from 400 to 1500 ppm.
d] mechanically agitating the elastomeric articles for about five minutes and
subsequently injecting ammonia and sodium thiosulphate using automatic metering
pumps
e] agitating the gloves for about ten minutes,
f] rinsing of the gloves in 10000 L of de-ionized water to remove all the residuals
g] tumbling the gloves in a dryer until dry
h] coating the dried gloves with a suitable slip agent

The present invention has been described primarily with respect to surgeon's and examination gloves. As earlier noted, the present invention is also applicable to other skin- or tissue-contacting flexible elastomeric articles, such as condoms, gloves used by doctors and veterinary surgeons for examination purposes (such gloves often being donned with dry hands), catheters, sheets, sheaths and sheath-type incontinence device.
The foregoing description and examples related only to preferred embodiments of the present invention and numerous changes and modifications may be made therein without departing from the spirit and scope of the invention as defined in the following claims.
The present invention has effects that cannot be accomplished by the prior art processing method.


CLAIMS
We claim:
1. A process for making a flexible rubber article consisting essentially of:
[a] immersing a clean profiled former in a coagulant solution, to produce a thin film of coagulant onto the former
[b] immersing the coated former into a rubber latex to coat the former with said latex;
[c] hot water leaching of the latex gel
[d] immersing the partially dried latex gel into a bath of formulated Polymer coating solution
[e] partially drying the polymer coating on the leached latex gel [f] curing the Polymer coating along with the latex gel
[g] leaching the cured latex film in hot water
[h] stripping the article off the formers
[i] post processing the article in a tumble drier
[j] powderfree processing involving either chlorination or polymer coating
2. The process of claim 1 (a) wherein the Coagulant bath is composed of a coagulant, a former release agent and a wetting agent.
3. The process of claim 1 (b) wherein the rubber latex used is natural rubber or synthetic rubber of the type butyl rubber, polyvinyl chloride, neoprene, carboxylated nitrile, viton, styrene butadiene copolymers, polyurethanes, or interpenetrating polymer network emulsion polymers, or combinations of these.
4. The process of claim 1 (d) wherein the polymer coating bath comprises a water-borne polymer and a- suitable slip agent just sufficient enough for uniform coating without causing bubbles in the bath
5. The process of claim 1 (j) wherein the articles after stripping off the mould are tumbled in a drier to remove excess moisture and powder

6. The process of claim 1 (j) wherein one side of the polymer coated article is
either chlorinated or treated with a polymer solution by an off-line method.
Off-line method involves processing of the articles in batches.
7. The process of claim l(j) wherein said aqueous chlorine solution contains from
500ppm to 1,500 ppm of chlorine.
Dated this the 29th day of December 2005.

Documents:

1989-che-2005 amended pages of specification 13-05-2011.pdf

1989-che-2005 amended claims 13-05-2011.pdf

1989-che-2005 amended claims 06-12-2010.pdf

1989-che-2005 amended claims 01-04-2011.pdf

1989-che-2005 correspondence others 13-05-2011.pdf

1989-CHE-2005 EXAMINATION REPORT REPLY RECIEVED 06-12-2010.pdf

1989-CHE-2005 CORRESPONDENCE OTHERS 01-04-2011.pdf

1989-che-2005 form-1( page no.2) 06-12-2010.pdf

1989-CHE-2005 ABSTRACT.pdf

1989-CHE-2005 CORRESPONDENCE OTHERS.pdf

1989-CHE-2005 CORRESPONDENCE PO.pdf

1989-CHE-2005 FORM 18.pdf

1989-che-2005-abstract.pdf

1989-che-2005-claims.pdf

1989-che-2005-correspondnece-others.pdf

1989-che-2005-description(complete).pdf

1989-che-2005-form 1.pdf

1989-che-2005-form 26.pdf

1989-che-2005-form 3.pdf

1989-che-2005-form 5.pdf


Patent Number 248073
Indian Patent Application Number 1989/CHE/2005
PG Journal Number 24/2011
Publication Date 17-Jun-2011
Grant Date 15-Jun-2011
Date of Filing 30-Dec-2005
Name of Patentee JOSE PAUL MELETH
Applicant Address FITCO INDIA, PLOT NO: 12-A,COCHIN SPECIAL ECONOMIC ZONE, KAKKANAD, COCHIN, KERALA-PIN 682 037
Inventors:
# Inventor's Name Inventor's Address
1 JOSE PAUL MELETH FITCO INDIA, PLOT NO: 12-A,COCHIN SPECIAL ECONOMIC ZONE, KAKKANAD, COCHIN, KERALA-PIN 682 037
2 JOSEPH JUDE EMMANUEL PERIERA FITCO INDIA, PLOT NO: 12-A,COCHIN SPECIAL ECONOMIC ZONE, KAKKANAD, COCHIN, KERALA-PIN 682 037
PCT International Classification Number A61F 2/06
PCT International Application Number N/A
PCT International Filing date
PCT Conventions:
# PCT Application Number Date of Convention Priority Country
1 NA