WO2010103351A1

WO2010103351A1 - An elastomeric article with a special moisture absorbing inner layer

Info

Publication number: WO2010103351A1
Application number: PCT/IB2009/053126
Authority: WO
Inventors: Deepthika De Silva; Lakshman Nethsinghe; Sunil Fernando
Original assignee: Dipped Products Plc
Priority date: 2009-03-12
Filing date: 2009-07-20
Publication date: 2010-09-16

Abstract

An elastomeric glove with two or more layers where the inner layer is moisture absorbing and its method of manufacturing is described here. An inner layer is composed of a mixture of polyacrylates together with a polysaccharide macromolecular material in order to effectively absorb moisture and thereby sweat when the glove is worn. Consequently the wearer of this glove will experience a higher level of comfort than when wearing a conventional glove. The glove may be a household glove/industrial glove or a medical glove. Its thickness may be from examination glove thickness to heavy duty industrial glove thickness. It may be unlined or flock lined. The composition of the outer layer of the glove is elastomeric and may be nitrile rubber, natural rubber neoprene rubber, styrene butadiene rubber or combinations there of. These outer layers may be vulcanized using the standard vulcanization formulations composed of sulphur/accelerator/zinc oxide formulations or they may also composed of an accelerator free rubber composition such as accelerator free nitrile latex.

Description

Description Title of Invention: AN ELASTOMERIC ARTICLE WITH A

SPECIAL MOISTURE ABSORBING INNER LAYER

REFERENCE TO RELATED APPLICATION

[1] This application claims prority over Sri Lanka Patent Application Serial No. LK/

P/l/15322 filed on March 12, 2009 and titled An Elatomeric Article With a Specila Moisture Absorbing Inner Layer . TECHNICAL FIELD

[2] This invention relates specifically to an elastomeric glove made where the first layer

( outer layer as worn ) is composed of an accelerator free nitrile elastomer and the inner layer is capable of absorbing moisture and there by sweat when the glove is worn. The inner layer is composed of a mixture of polyacylates together with a polysaccharide macromolecular material evenly distributed therein. The moisture ab- sorbance capability is due to this polysaccharide macromolecular material.

[3] The glove may be flock lined or unlined and is made using conventional dipping technology. In the case of flock lined product, the polyacrylate mixture is applied to the product as the last dip prior to application of the flock. In the case of unlined gloves, the polyacrylate mixture is the last dip prior to curing.

[4] Other types of elastomers also be used as the layer lof the glove. These include, natural rubber, neoprene rubber , styrene butadiene rubber of combinations there of.

[5] A sketch of the glove showing its make up is shown below:

BACKGROUND OF THE INVENTION

[6] Household gloves are widely used in numerous domestic applications such as kitchen work, cleaning, gardening, light assembly, plant maintenance, janitorial applications, waste collection etc. The gloves are also used in the food processing industry and pharmaceutical industry.

[7] When a glove is worn for any length of time, the wearer of the glove feels some discomfort. The reason for this discomfort is due to sweating. The invented glove has an inner layer which is capable of absorbing moisture sweat) thus enhancing the comfort.

RELATED PRIOR ART

[8] The presence of this absorbing layer between the skin and the elastomeric part of the glove provides a certain barrier to type I and type IV allergens. Nevertheless use of type I and Type IV allergen free systems are preferred. US patent no: US20080034467A1 refers to an elastomeric flexible article with absorbent polymer and manufacturing method. The patent refers in particular to gloves. The moisture absorbing characteristics are realized by having an inner elastomeric layer containing a superabsorbent material in particular a superabsorbent polymer selected from a group of synthesized polymers such as polyacrylamide, polyacrylate, polyacrylic acid and related copolymers and starch (or cellulose) graft acrylonitrile (or epoxy chloro propane vinylacetate) copolymers or terpolymers. Another patent PCT/ US2004/010499 refers to a method of making an elastomeric article including preparing a non-woven fibrous polymer composition for dip-coating onto a layer of carboxylated acrylonitrile-butadiene elastomeric surface and in particular making industrial or household gloves. The polymer composite fibrous coating is composed of an elastomer or elastomer blend, a fibre or fibre blend, a surfactant, and a micronized wax. The coating provides improved sweat management to a user.

[9] The present invention refers to conferment of moisture absorbing property by having an inner layer in the glove composed of a mixture of polyacylates together with a polysaccharide macromolecular material evenly distributed therein either as a neat film or dispersed in an elastomeric layer. The polysaccharide macromolecular material is mixed in with the pollyacrylate material as a solution and not grafted onto any polymer backbone per se. SUMMARY OF THE INVENTION

[10] The present invention is directed to a multi layered glove wherein the interior surface of the glove has the ability of absorb sweat on the skin when the glove is worn.

[11] According to another embodiment of the present invention, there is a method for making a thin, household glove, containing three layers. The method comprises forming a first elastomeric material layer which in itself may be multilayered This first layer may be composed of several layers which may be of different elastomers and/or colours. The second layer, the second layer is the moisture absorbing layer and is composed of an acrylic matrix in which a polysaccharide macromolecular material is dispersed uniformly either as a neat film or dispersed in an elastomeric layer. The third layer is a coating of flock of the fibrous form which although is not its prime purpose has the ability to absorb and transfer sweat to the second layer. The third layer is not necessary for the moisture absorbing capability function. The second layer itself has this function and when next to the skin will absorb moisture layer. In the absence of the third layer, the glove would be unlined. BRIEF DESCRIPTION OF THE DRAWINGS

[12] Figs. 1 depicts a skecth of the glove showing the make up layers. The layer marked 1 is the innermostt layer of polyacrylate matrix containing polysaccharide macromolecular material either as a neat film or dispersed in an elastomeric layer. The layer marked 2 is the middle layer of flock(optional) of cotton etc.. The layer marked 3 is the outtermost layer composed of an accelarator free nitrile elastomer. Other typres of elastomers which it may be composed include, natural rubber, nitrile rubber, neoprine rubber, styrene butadiene rubber or combinations thereof. DETAILED DESCRIPTION

[13] The present invention provides a glove which is capable of absorbing moisture on hand (in the form of sweat) when the glove is worn, hence providing more comfort to the wearer.

[14] In some embodiments of the present invention, glove has three layers. The first layer

1 is elastomeric. The second layer is the coating and the third layer may be cotton flock.

[15] The first layer is the outer most layer to the skin when the glove is worn and the second layer will be the middle layer and the third layer will be the inner most layer closest to the skin when the glove is worn. The second layer and the third layer have independent as well as synergistic mechanisms to absorb moisture (sweat) from the hand, when the glove is worn. The synergistic mechanism includes absorbing excess moisture on the hand from the third layer and transferring this absorbed moisture to the second layer, there fore maintaining a relatively dry interior glove surface. When the glove is removed, this mechanism reverses. For example, the stored moisture in the second layer is transferred to the third layer, which will be evaporated to the environment from the third layer. This mechanism operates according to the osmotic gradient. Also the second layer and the third layer have the ability to absorb excess moisture on hand when the glove is worn independently. The ultimate result of this absorption of excess moisture on the hand will be a relatively dry comfortable feeling to the wearer when the glove is worn. The third layer is not necessary for the moisture absorbing capability function. The second layer itself has this function and when next to the skin will absorb moisture layer

[16] According to some embodiments of the present invention, the elastomer composing the first layer is accelerator free (accelerator free nitrile latex based).

[17] In some embodiments of the present invention, use of an accelerator free latex ( e.g. accelerator free nitrile latex ) allows the glove to be free of type I and type IV allergens.

[18] In some embodiments of the present invention, the glove is made from at least three layers, the first layer, the second layer, and the third layer . The first layer is made as a single layer of fluid impermeable polymeric material that can act as a barrier to help protect the user's hand from infectious agents and mechanical risks. It is preferably made, but not limited to nitrile (acrylonitrile butadiene rubber), carboxylated nitrile, polyurethane, styrene butadiene rubber, polychloroprene rubber, synthetic poly- isoprene rubber, polybutadiene rubber and the blends of the above mentioned rubbers. [19] The second layer, which is capable of absorbing excess moisture through osmotic gradient, , so that, it can absorb excess moisture on the hand, when the glove is worn. In addition, this said layer is composed of a mixture of polyacrylates either as a neat film or dispersed in an elastomer which could include materials of the type poly acrylic acid, poly acrylate salts, polymethacrylate, poly vinyl acetate, and esters of the afore mentioned materials. Within this matrix is a moisture absorbing material which is dispersed uniformly throughout the matrix. This moisture absorbing material is highly absorbent polysaccharide macromolecular material. Due to the presence of this material evenly through out the second layer, when the glove is worn, this layer has the ability to uniformly absorb moisture (sweat) from the hand directly as well as accept and store moisture transferred via the third layer, thus keeping the inner surface of the glove relatively comfortable.

[20] The preferred embodiment of the present invention is a glove where in the moisture absorbing material in the above said second layer is a polysaccharide macromolecular material and preferably carboxy methyl cellulose or any derivative there of. The absorption mechanism of this cellulose material is based on the fact that the macromolecular chain contains a plurality of anionic carboxyl and hydroxyl groups, which make it possible for the polymer to by means of osmotic forces absorb aqueous liquids by making hydrogen bonds with water molecules. Other materials having similar structural adaptations to make hydrogen bonds with water may also be used in place of the polysaccharide macromolecular material. These include gelatins, starch, dextrins, polyvinyl alcohols, hydrophilic macro/nano clays and hydro gel materials.

[21] In order to disperse the polysaccharide macromolecular material uniformly through out the second layer, the said polysaccharide macromolecular material is added as a solution to a solution of the polyacrylates which constitute the rest of the matrix of the moisture absorbing layer during the preparation of the material mixture which constitutes the second later of the glove when the film is a neat acrylic layer. The second lay can also be composed of the afore mentioned materials (polysaccharide macromolecular material plus acrylics solution dispersed in latex. The latex is composed of the same material described in clause 0011.

[22] In order to form the second layer during the glove manufacturing procedure, any competent method can be used. For example dipping processes and spraying processes. In the dipping process, a former on which the first layer (elastomeric layer;) has been coated, is dipped into a solution which contains polysaccharide macromolecular material evenly distributed in a mixture of polyacrylates. Alternately it is dipped into a latex composition which contains the solution which contains the polysaccharide macromolecular material/ polyacrylates mixture . Then the former is withdrawn from this solution and dried. The film so formed on the first layer constitutes the moisture absorbing second layer of the glove. Similarly, in the spraying process, the solution of the polysaccharide macromolecular material mixed with the mixture of polyacrylates is spayed by means of a suitable spaying mechanism to form a continuous layer on the elastomeric film which constitutes the first layer. In both instances cited above, first layer need not be totally dry or vulcanisd. It can merely consist of gelled film of the latex elastomer.

[23] Embodiments of the present invention include a glove which has a second layer containing the polysaccharide macromolecular material which is dispersed homogeneously through out this layer . The amount of the polysaccharide macromolecular material in the second layer is from about 0.085% by weight to 2% by weight of the total dry weight of this said second layer of the glove and is preferably utilized at a dose of 1%

[24] Embodiments of the present invention have a cellulose derivative in the second layer.

[25] Embodiments of the present invention include a third layer, which is composed of flock.. Flock is defined as shortly cut or milled textile fibres. The second layer acts as the adhesive for the flock layer. The primary purpose of the flock is to enable donning, however it is also capable of absorbing sweat and transmitting it to the moisture absorbing second layer, therefore may serve to increase the effectiveness of moisture absorbance capability of the glove described in this invention.

[26] The flock used for the present invention may be composed of either natural materials such as cotton, wool, cellulose, or synthetic materials such as rayon, nylon, polyester etc. and combinations of these. It is commercially available material, used widely in the glove manufacturing dipping industry. The colour of the flock is immaterial. White or colored flock can be used. The flock is applied by conventional methodology ,well known in the art of dipped glove manufacture . It is applied to the glove over the second dip layer via spraying using electrostatic or any non-electrostatic conventional mechanism. Flock may be either non activated or activated chemically or physically.

[27] The glove in which the first layer is a nitrile elastomer , the second layer which is capable of absorbing moisture (in the form of sweat) from the hand when the glove is worn and the third layer being flock was tested for its effectiveness in moisture absorbance by an 'in- vitro' test . In this test, a circular test specimen is clamped across the bottom of a hollow cylinder and a specified volume of water is poured into the top of the cylinder. After a set time, the mass of water absorbed by the test specimen is measured. The test is carried out after conditioning the samples at 23+2⁰C and 50+2% relative humidity. The results are given below in the table 01. According to this table, it is clear that the invented glove has considerably higher moisture absorbance capability than conventional gloves.

[28] [Table 1] [Table ]

[29] Table 01 - Surface moisture absorbance of the invented glove vs conventional nitrile glove

[30] Similar results are obtained f at other temperatures and relative humilities.

[31] The fundamental method of preparing the glove according to the present invention comprises following sequence.

[32] A clean glove former/mold having the form of a human hand is dried and heated to the appropriate temperature, preferably a temperature between 45⁰C to 65⁰C, using any competent method. For example, any conventional method like oven, radiation etc.

[33] The heated former is dipped in to the powder free coagulant (PFC), which is then partially dried using any competent method. For example, any conventional method like oven, radiation, fan, air etc.

[34] The first layer , which will be the outer most layer when the glove is worn is formed on this former using any competent method, preferably by dipping the former in to a tank which is consisting the compound relevant to the first layer, and an example formulation for this compound is given in the table 2. This example formulation is merely an example, and it would be apparent to those of ordinary skill in the art of the latex industry, that the example formulation can be changed, even dramatically in some cases, and still embody the various embodiments of the present invention. For example, many ingredients in the table are merely optional ingredients or particular embodiments or examples of classes of ingredients. For example the ingredients such as colorant, odorant, latex stabilizers are optional ingredients. Further the quantities or quantity ranges may vary according to the process /plant in which the glove is manufactured.. The first layer is a single, continuous, film which confers the desired barrier properties for the glove.

[35] [Table 2] [Table ]

[36] Table 2 - An example formulation for the compound for 1^st layer [37] There after, the former with the formed first layer is leached in water, preferably having temperature between 45⁰C to 7O⁰C. The temperature, duration, and other leaching parameters may be changed according to the process/plant on which the product is manufactured. The former with the so formed first layer is dried using any competent method, for example using fans, radiation, oven.

[38] The second layer coated onto the first later by any competent method. For example by employing a dipping proceor by a spraying process. In the dipping process, the glove former which contains already formed first layer, is dipped in to a solution of acrylic polymer and the polysaccharide macromolecular material. Alternately it is dipped into a latex composition which contains the solution which contains the polysaccharide macromolecular material/ polyacrylates mixture .Then the former is withdrawn from this solution after depositing a continuous second layer containing super absorbent polymer. Similarly, in the spraying process, into a glove former which contains already formed first layer 1, a solution which contains super absorbent polymer is spayed by means of a suitable spaying mechanism to form a continuous layer of the solution containing super absorbent polymer on the glove former having already formed first layer.

[39] An example formulation for this compound is given in the table 3 and 4. This example formulation is merely an example, and it would be apparent to those of ordinary skill in the art that the example formulation can be changed, even dramatically in some cases, and still embody various embodiments of the present invention. For example, many ingredients in the table are merely optional ingredients or particular embodiments or examples of classes of ingredients. Merely for example, colorant, odorant, latex stabilizer or the like are optional ingredients. For another example, the example quantities or quantity ranges can vary. The second layer is a single, continuous, non porous, layer having barrier properties.

[40] [Table 3] [Table ]

[41] Table 3 - An example formulation when 2^nd layer is composed only of the poly- acrylate/polysacaride mactomolecullar mixture. [42] [Table 4] [Table ]

[43] Table4: An example formulation when 2^nd layer is composed of the poly aery late/ polys acaride mactomolecullar mixture in latex [44] Thereafter, the third layer, is applied on the second layer using any competent method known in the industry for example spraying on to the second layer. [45] The former with the 3 layers is sent to the drying and curing oven directly without leaching.

[46] The former with the formed 3 layers is dried/cured for about 40 minutes at 13O⁰C and stripped off from the former. After oven curing, post cure leaching may be given. The stripped gloves may be given any finishing treatment such as washing, chlo- rination, silicone spraying etc. such as that normally used in the glove manufacturing industry and the gloves are dried using any competent method, for example tumble drying.

[47] It should be understood that various changes and modifications to the embodiments described here in will be apparent to those skilled in the art of glove manufacture . Such changes and modifications can be made with out departing from the spirit and scope of the present invention and without demising the attendant advantages. It is, there fore, intended that such changes and modifications be covered by the appended claims.

[48]

[49]

[50]

Claims

[Claim 1] An elastomeric glove with an inner layer which is capable of absorbing moisture wherein the moisture absorbing property is achieved by having an inner layer in the glove composed of a mixture of poly- acylates together with a polysaccharide macromolecular material evenly distributed therein by way of mixing polysaccharide macro- molecular material with the polyacrylate material.

[Claim 2] The glove as claimed in claim 1 wherein the glove is flock lined/ unlined with a thickness preferably 0.1 to 1.0 mm.

[Claim 3] The glove as claimed in claim 1 wherein the outer layer of the glove is an elastomer composed from nitrile latex, natural rubber latex, neoprene latex, SBR latex or blends of nature rubber latex , neoprene latex and nitrile latex .

[Claim 4] The glove as claimed in claim 1 wherein the second layer of the glove ( in the case of flocklined gloves) or the innermost layer (in the case of unlined gloves) contains a polysaccharide macromolecular material dispersed evenly in a supportive matrix either as a neat film or dispersed in an elastomeric layer . The supportive matrix is preferably a poly acrylate polymer compatible with rubber elastomer of the glove . Other polymers which may be used as the supportive matrix include polyacrylicacid, polyacrylate salts, polymethacrylate, polyvinylacetate, and esters of therse materials, either neat or dispersed in an elastomeric layer.

[Claim 5] The glove as claimed in claim 1 wherein the polysaccharide macromolecular material is a cellulose derivative.

[Claim 6] The glove as claimed in claim 1 wherein the second layer contains the polysaccharide macromolecular material from preferably 0.085 to 1% by dry weight.

[Claim 7] The glove as claimed in claim 1 wherein the polysaccharide macromolecular material is evenly distributed within and throughout the second layer of the glove.

[Claim 8] The glove as claimed in claim 1 wherein the polysaccharide macromolecular material is spread in a supportive matrix which is consists of a mixture of polyacrylates either as a neat film or dispersed in an elastomeric layer.

[Claim 9] The glove as claimed in claim 1 wherein the glove is lined with flock made of cotton/ polyester cotton/ rayon or any other material commonly use in the glove industry.

[Claim 10] The glove as claimed in claim 1 wherein the elastomeric layer/s is/are accelerator free as in the case of accelerator free nitrile latex.

[Claim 11] The glove as claimed in claim 1 wherein the innermost layer is accelerator and sulphur free.

[Claim 12] A method of making the glove as claimed in claim claims 1 to 11 wherein the method of manufacture is by way of dipped in to a coagulant, latex (single or multiple), and dip(single or multiple), in to an aqueous solution of the polysaccharide macromolecular material described in claim 5

[Claim 13] The method as claimed in claim 12 wherein the step of forming the first layer precedes the step of forming the second layer.

[Claim 14] The method as claimed in claim 12 wherein the step of forming the second layer precedes the step of forming the third lining.

[Claim 15] The method as claimed in claim 12 wherein the third lining is composed of flock.

[Claim 16] The method as claimed in claim 12 wherein the step of forming the first layer comprises dipping a heated glove former into coagulant, which is then partially dried in air, followed by a single latex dip. A single latex layer is formed on the glove former as the first layer.

[Claim 17] The method as claimed in claim 12 , wherein the step of forming the second layer on top of the first layer by dipping the glove formers with the first single latex layer in a solution containing a mixture of poly aery lie acids, poly acrylates, polyvinyl acetate and/or their copolymers with a polysaccharide macromolecular material specifically a cellulose derivative with or without latex.

[Claim 18] The method as claimed in claim 12, wherein the step of forming the third lining is by a spraying technique

[Claim 19] The method as claimed in claim 4 wherein prior to the step of forming the second layer, the solution containing the polysaccharide macromolecular material is prepared by dissolving the absorbent polysaccharide macromolecular material in hot water and allow it to cool and add it slowly to a mixture containing poly aery lie acids, poly acrylates, polyvinyl acetate and/or their copolymers.

[Claim 20] The method as claimed in claim 12 wherein prior to the step of forming the second layer, the solution containing polysaccharide macromolecular material is prepared by dissolving the polysaccharide macromolecular material in hot water.