A METHOD FOR PRODUCING AT LEAST TWO DISCRETE GLOVES ON

ONE FORMER FIELD OF TECHNOLOGY

The present invention relates generally to rubber gloves and methods of making them. More particularly, it relates to a method of producing more than one glove on one former. BACKGROUND OF THE INVENTION

Glove manufacturing process has shifted from single former line system to double, even triple former line system so as to increase production capacity. However, shifting from an existing line requires investment in time, manpower, apparatus and money. To avoid this, the existing glove manufacturing process was modified. This invention provides a method for producing more than one glove on one former, such that production capacity of an existing former line system can be improved without additional investment in apparatus.

SUMMARY OF THE INVENTION

One object of the present invention is to provide a method for producing more than one glove on one former. Such method can be adopted by existing single, double, or triple former line system to improve production capacity. Another object of the present invention is to provide a method for producing more than one glove on one former, in which the gloves are eventually strippable into more than one discrete glove without being fused together.

At least one of the preceding objects is met, in whole or in part, by the present invention, in which one of the embodiments of the present invention is a method for producing two discrete gloves on one former, comprising steps of: (a) coating a glove former with a first coagulant and drying thereof; (b) dipping the former in a first compounded rubber comprising an anti-tack agent and forming a first rubber film on the former and partially curing thereof; (c) treating the first rubber film with a first donning agent; (d) coating the first rubber film with a second coagulant and drying thereof; (e) dipping the first rubber film in a second compounded rubber comprising an anti-tack agent and forming a second rubber film on the first rubber film and curing thereof; and (f) treating the second rubber film with a second donning agent and stripping two discrete gloves therefrom, in which the coefficient of friction between the first and second rubber films ranges from 0.39 to 0.54 pk such that they are strippable into discrete gloves thereafter.

Preferably, the method further comprises a step of leaching excess compounded rubber or donning agent on the film.

Preferably, the method further comprises a step of beading cuff region of the rubber film prior to curing. Preferably, the anti-tack agent is present in an amount of 0.5 to 5 phr in the compounded rubber.

Preferably, the donning agent is a chlorinated or polymeric donning agent. Preferably, the chlorinated donning agent used comprises at least 400 ppm of chlorine.

Preferably, the polymeric donning agent used comprises 0.5 to 5 wt% of polymer in water.

Preferably, the polymeric donning agent comprises butyl acrylate, acrylate copolymer, methacrylic acid, benzenepropanoic acid, isopropyl alcohol, and potassium hydroxide.

Preferably, the anti-tack agent is a polyolefin-based wax.

Preferably, the method produces a glove having a thickness between 0.01 mm to 3 mm.

BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 shows a flowchart representing the present invention.

DETAILED DESCRIPTION OF THE INVENTION

This invention relates to a method for producing more than one glove on one former.

Exemplary, non-limiting embodiments of the invention will be disclosed. However, it is to be understood that limiting the description to the preferred embodiments of the invention is merely to facilitate discussion of the present invention and it is envisioned that those skilled in the art may devise various modifications without departing from the scope of the appended claim.

As shown in Fig. 1, the present invention is a method for producing two discrete gloves on one former, comprising a step of: (a) coating a glove former with a first coagulant and drying thereof; (b) dipping the former in a first compounded rubber comprising an anti- tack agent and forming a first rubber film on the former and partially curing thereof; (c) treating the first rubber film with a first donning agent; (d) coating the first rubber film with a second coagulant and drying thereof; (e) dipping the first rubber film in a second compounded rubber comprising an anti -tack agent and forming a second rubber film on the first rubber film and curing thereof; and (f) treating the second rubber film with a second

donning agent and stripping two discrete gloves therefrom, in which the coefficient of friction between the first and second rubber films ranges from 0.39 to 0.54 pk such that they are strippable into discrete gloves thereafter. Prior the step (a), it is preferred that the glove former is clean. Used glove former can be washed with acid, alkaline or neutral type cleaning agent to remove residue or dirt thereon. The washing can be conducted at 50 to 70 °C for a duration of at least 10 seconds. Thereafter, the former is preferably dried and used in step (a). The first coagulant can have the same or different composition to the second coagulant. Preferably, the first and second coagulant has the same composition. Coagulant comprised of 4 to 20 wt% of calcium nitrate is preferably used. Further, the coagulant may comprised of 0.1 to 3 wt% of a mould releasing agent, such as a stearated-based coagulant, 0.01 to 0.5 wt% of non-ionic surfactant, and 0.01 to 0.2 wt% of pH adjuster.

In accordance to the preceding description, the step of (a) coating a glove former with a first coagulant can be performed at 50 to 60 °C for at least 5 seconds, for instance 30 seconds. The step of (d) coating the first rubber film with a second coagulant can also be performed at 50 to 60 °C for at least 5 seconds, for instance, 30 seconds. After the step (a) and (d), the first and second coagulant are preferably dried in an oven at 100 to 180 °C for at least 30 seconds. More preferably, at least 3 minutes.

The method in the present invention is able to produce a glove having a thickness between 0.01 mm to 3 mm. It shall be understood that the first coagulant composition and working parameters in step (a) can be adjusted to enhance coating of the first compounded rubber thereafter. Further, it ensures easy stripping of the first rubber films from the former. On the other hand, the second coagulant composition and working parameters in step (d) can be adjusted to enhance coating of the second compounded rubber thereafter. Further, in

association with the second compounded rubber, it ensures easy stripping of the second rubber films from the first rubber films.

In accordance to the preceding description, the step of (b) dipping the former in a first compounded rubber comprising an anti-tack agent and forming a first rubber film on the former can be conducted at 25 to 40 °C for at least 5 seconds, for instance for a duration of 5 to 60 seconds. The step of (e) dipping the first rubber film in a second compounded rubber comprising an anti-tack agent and forming a second rubber film on the first rubber film can also be conducted at 25 to 40 °C for at least 5 seconds, for instance 60 seconds. The period of dipping can be adjusted based on desired thickness of the first and second rubber film. After the step (b) and (e), the first and second rubber films are preferably cured in an oven at 70 to 150 °C for a duration of at least 3 minutes, such as 3 to 45 minutes. Preferably, in step (b), the first rubber film is partially cured in an oven at 70 to 150 °C for a duration of at least 3 minutes, such as 3 to 45 minutes, more preferably for a duration of 5 minutes. Further, in step (e), the first rubber film is simultaneously cured with the second rubber film in an oven at 70 to 150 °C for a duration of at least 5 minutes, such as 10 to 45 minutes. Such method is able to prevent over-curing of the first rubber film.

In the present invention, the first compounded rubber can have the same or different composition to the second compounded rubber. The rubber used can be a natural rubber latex. Alternatively, it can be synthetic rubber selected from copolymer of acrylonitrile and butadiene, carboxylated copolymer of acrylonitrile and butadiene, polyisoprene, polychloroprene, polyurethane, polyvinyl chloride, thermoplastic elastomers, or derivatives thereof. Further, it is preferred that the first and second compounded rubber comprises suitable amount of anti-tack agent selected from polyolefin-based wax. For instance, polyethylenes under the trade name Polywax can be used. More particularly, the anti-tack agent is present in an amount of 0.5 to 5 phr in the compounded rubber. According to the foregoing description, the presence of anti-tack agent in the compounded rubber ensures easy stripping of glove films thereafter.

In the present invention, the method comprises the step of (c) treating the first rubber film with a first donning agent and a step of (f) treating the second rubber film with a second donning agent. Preferably, the step of treating (c) and (f) can be conducted by dipping cured films into a tank containing donning agent at room temperature for a duration of at least 3 seconds, such as 30 seconds. The first donning agent used can have the same or different type to the second donning agent. More preferably, the donning agent used can be a chlorinated or polymeric donning agent. In one embodiment, the first or second rubber film can be subjected to drying and cooling steps before being treated with the chlorinated donning agent. In another embodiment, the first or second rubber film may not necessarily be subjected to the cooling step before being treated with the polymeric donning agent. Nevertheless, the first or second rubber film may still be subjected to a drying step after treated with polymeric donning agent. The chlorinated donning agent comprising at least 400 ppm of chlorine, more particularly 400 to 1000 ppm of chlorine can be used. Optionally, polymeric donning agent comprising of 0.5 to 5 wt% of polymer in water can also be used. More particularly, the polymeric donning agent comprises butyl acrylate, acrylate copolymer, methacrylic acid, benzenepropanoic acid, isopropyl alcohol, and potassium hydroxide. Other ingredients of the polymeric donning agent are comprised of silicone, wetting agent, thickener, biocide, pH adjuster, and water.

The method further comprises a step of leaching excess chemicals or residues on the first and second rubber films. It can be conducted after the drying or curing steps, and after the steps of treatment with chlorinated or polymeric donning agent. Preferably, the step of leaching is conducted by washing the rubber films with water at 40 to 70 °C for a duration of at least 15 seconds, such as 300 seconds.

In the present invention, the dipping step of (b) and (e) can be adjusted such that cuff regions of the first and second rubber film are having different lengths. For instance, a difference of 1 to 3 cm. In this way, gloves with beading can be separated easily. The

method further comprises a step of beading cuff region of the first and/or second rubber film prior to curing. The sequence of beading step in the method of the present invention may differ depending on the type of donning agent used. In one embodiment, the beading step is conducted before subjecting the first or second rubber film to treatment using chlorinated donning agent. Alternatively, the beading step can be conducted after subjecting the first or second rubber film to treatment using polymeric donning agent.

In contrast to a multiple dip process as exemplified in Patent Cooperation Treaty (PCT) Patent Application Publication No. WO 1996025279 Al, the present invention does not combine or fuse the first and second rubber films during curing step. The steps as disclosed in the foregoing description renders the coefficient of friction (COF) between the first and second rubber films ranges from 0.39 to 0.54 pk such that they do not fuse with each other thence strippable into discrete gloves thereafter.

The present invention may be embodied in other specific forms without departing from its essential characteristics. The described embodiments are to be considered in all aspects only as illustrative and not restrictive. The scope of the invention is, therefore indicated by the appended claims rather than by the foregoing description. All changes, which come within the meaning and range of equivalency of the claims, are to be embraced within their scope.