MULTILAYER SYNTHETIC RUBBER COMPOSITIONS

Abstract

Provided are multilayer synthetic rubber compositions formed from a layer of a styrene block copolymer composition and a layer of one or more synthetic elastomers, such as polychloroprene, polyisoprene, nitrile rubber, styrene butadiene rubber, butyl rubber and polyurethane. The multilayer compositions find use in the manufacture of thin walled articles, for example gloves, particularly medical or industrial gloves.

Claims

1. A multilayer composition comprising: (a) a first layer comprising a styrene block copolymer (SBC) composition, said styrene block copolymer (SBC) composition comprising one or a mixture of SBCs of number average molecular weight (Mn) above 100,000 g/mol; (b) a second layer comprising one or more synthetic elastomers and, optionally, one or more styrene block copolymers (SBCs); and (c) optionally, one or more further layers.

2. A multilayer composition according to claim 1, wherein the SBC composition of the first layer comprises at least one SBC selected from the group consisting of linear, radial or star SEBS, SEPS, SEEPS, SBSS, SIS, SBS, SIBS, and combinations thereof.

3. (canceled)

4. A multilayer composition according to claim 1, wherein the SBC of the first layer comprises an SBC with a saturated elastomeric mid-block.

5. A multilayer composition according to claim 1, wherein the SBC composition of the first layer further comprises one or more plasticizers.

6. A multilayer composition according to claim 5, wherein the plasticizer comprises a liquid or a mixture of liquid saturated polyolefins compatible with the midblock (elastomeric block) of the SBC.

7. A multilayer composition according to claim 5, wherein the plasticizer is selected from one or more vegetable oils, such as sunflower, rapeseed, or coconut oil or an oligomer or other elastomer that possesses sufficient compatibility with the rubbery mid-blocks, such as a low molecular weight polybutadiene, polyisoprene, polyisobutene, amorphous polyolefin copolymers of propylene and ethylene, and butyl rubber.

8. A multilayer composition according to claim 1, wherein the SBC composition of the first layer further comprises one or more reinforcing resins and/or fillers.

9. A multilayer composition according to claim 8, wherein the reinforcing resin is one or more low molecular weight polymers miscible with the PS block, such as aromatic resins, and copolymers comprising a block miscible with the PS block, such as styrene maleic anhydride (SMA) resins and ionomer resins and/or wherein the reinforcing filler is one or more of reinforcing silica, carbon black fillers, and fibres.

10. A multilayer composition according to claim 1, wherein the SBC composition of the first layer further comprises conventional rubber additives, such as, pigments, primary and secondary antioxidants, fillers (mineral or organic), vulcanization and crosslinking agents, photo-initiator, anti-static agents, anti-foam, surfactants, and combinations thereof.

11. A multilayer composition according to claim 1, wherein the SBC composition of the first layer further comprises functional additives selected from anticorrosion agents, lubricants, chemical markers, phase-change products, energetic-particle (radiation) decelerators, agents with disinfecting power, odoriferous agents or moisturizers, dyes for detecting cuts, and combinations thereof.

12. A multilayer composition according to claim 1, wherein the synthetic elastomer is selected from the group consisting of polychloroprene (CR), polyisoprene (IR), nitrile rubber (NBR), styrene butadiene rubber (SBR), butyl rubber (IIR), polyurethane (PUR) and combinations thereof.

13. A multilayer composition according to claim 12, wherein the synthetic elastomer further comprises one or more additives selected from plasticizers, reinforcing resins and fillers, crosslinking additives (vulcanization or/and other chemical crosslinker systems), primary and secondary antioxidants, processing resins and chemicals (surfactants, sodium hydroxide) or mold release agents.

14. A multilayer composition according to claim 1, wherein the synthetic elastomer comprises a blend of CR and SBC, or a blend of IR and SBC, or a blend of CR and IR, or a blend of CR and NBR, or a blend of CR, NBR and SBC.

15. A multilayer composition according to claim 1, wherein the first layer comprises SBC, for example SEBS, and the second layer comprises a blend of SBC (SIS) and IR, wherein the weight ratio of SIS to IR is greater than 50%.

16. A multilayer composition according to claim 1, wherein the first layer comprises an SBC composition, for example SEBS, and the second layer comprises a blend of NBR and CR, wherein the weight ratio of CR to NBR is greater than 50%.

17. A multilayer composition according to claim 1, wherein the CR is selected from homopolymer of chloroprene (2-chlorobutadiene-1,3) or a copolymer of chloroprene and a comonomer (2,3-dichloro-1,3 butadiene).

18. A multilayer composition according to claim 1, wherein the total thickness of the multilayer composition may be between about 10 microns and about 500 microns, preferably between about 50 microns and about 350 microns, more preferably between about 100 microns and about 300 microns.

19. A multilayer composition according to claim 1, wherein the total thickness of the multilayer composition is less than 500 microns, or less than 400 microns.

20. A multilayer composition according to claim 1, wherein the ratio of the thickness of the first layer to the thickness of the second layer is between about 2:1 to about 20:1, preferably between about 3:1 to about 10:1.

21. An article of manufacture comprising a multilayer composition according to claim 1.

22. An article of manufacture according to claim 21, wherein the article is a glove.

23.-33. (canceled)

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0077] FIG. 1 is flow chart outlining a process for making a glove according to one embodiment of the present disclosure.

DETAILED DESCRIPTION OF THE EMBODIMENTS

[0078] The following is a detailed description of the disclosure provided to aid those skilled in the art in practicing the present disclosure. Those of ordinary skill in the art may make modifications and variations in the embodiments described herein without departing from the spirit or scope of the present disclosure.

[0079] Although any methods and materials similar or equivalent to those described herein can also be used in the practice or testing of the present disclosure, the preferred methods and materials are now described.

[0080] It must also be noted that, as used in the specification and the appended claims, the singular forms ‘a’, ‘an’ and ‘the’ include plural referents unless otherwise specified. Thus, for example, reference to a ‘SBC’ may include more than one SBCs, and the like.

[0081] Throughout this specification, use of the terms ‘comprises’ or ‘comprising’ or grammatical variations thereon shall be taken to specify the presence of stated features, integers, steps or components but does not preclude the presence or addition of one or more other features, integers, steps, components or groups thereof not specifically mentioned.

[0082] Unless specifically stated or obvious from context, as used herein, the term ‘about’ is understood as within a range of normal tolerance in the art, for example within two standard deviations of the mean. ‘About’ can be understood as within 10%, 9%, 8%, 7%, 6%, 5%, 4%, 3%, 2%, 1%, 0.5%, 0.1%, 0.05%, or 0.01% of the stated value. Unless otherwise clear from context, all numerical values provided herein in the specification and the claim can be modified by the term ‘about’.

[0083] Any methods or processes provided herein can be combined with one or more of any of the other methods or processes provided herein.

[0084] Ranges provided herein are understood to be shorthand for all of the values within the range. For example, a range of 1 to 50 is understood to include any number, combination of numbers, or sub-range from the group consisting of 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, or 50.

[0085] Reference will now be made in detail to exemplary embodiments of the disclosure. While the disclosure will be described in conjunction with the exemplary embodiments, it will be understood that it is not intended to limit the disclosure to those embodiments. To the contrary, it is intended to cover alternatives, modifications, and equivalents as may be included within the spirit and scope of the disclosure as defined by the appended claims.

[0086] In medical glove applications, a multilayer composition comprising a first layer of SBC (SEBS) and a second layer comprising a blend of SBC (SIS, 80%) and IR (20%) advantageously offers the required level of chemical resistance, while maintaining the excellent flexibility and dexterity provided by the SBC.

[0087] In industrial applications, electrical insulating gloves designed for enhanced electrical insulation protection may comprise a multi-layer composition, wherein the first layer comprises an SBC composition, advantageously SEBS. The SBC layer may be prepared by solvent casting. The second layer comprises a blend of NBR (30%) and CR (70%). The multi-layer material provides superior feel-fit and dexterity performance to products currently in the marketplace. The blend of NBR and CR provides protection to the SBC first layer performance against mechanical and chemical aggression while the first layer provides the electrical insulation protection and the resistance to degradative oxidation, especially ozone.

Example 1: Multilayer Composition Comprising a First Layer of SEBS with a Second Layer of a Latex Blend CR/NBR

[0088] So that the manner in which the above recited features of the present disclosure can be illustrated a brief description of a process flowchart is depicted in FIG. 1. It is to be noted, however, that the flowchart and disclosure depict exemplary embodiments of the disclosure and are therefore not to be considered as limiting the scope of the disclosure.

[0089] In this example to illustrate the present disclosure, cleaned glove formers may be dipped in a coagulant mixture of calcium nitrate, a non-ionic wetting agent such as an ethoxylated fatty alcohol and a release agent, for example calcium carbonate or a stearate salt, wax and silicone dispersed in water.

[0090] The coagulant on the formers may then be dried and dipped in a latex composition (synthetic elastomers): in this example a mixture of polychloroprene (CR) and a carboxylated butadiene nitrile (NBR) may be used and compounded as outlined in Table 1.

TABLE-US-00001 TABLE 1 compounding of latex blend of CR and NBR latex Ingredient phr CR Latex 70 NBR Latex 30 Sodium dodecylbenzene 0.3 sulfonate (SDBS) Sodium Hydroxide 0.2 ZnO 3.5 Butylated reaction product of 1 p-cresol and dicyclopentadiene (antioxydant) Zinc dithiocarbamate (ZDEC) 1 Sulfur 1

[0091] The film formed at the surface of the glove former may then be leached in hot water, crosslinked by heating in an oven, leached, then dried clean, so the surface is free from any contamination for the next dipping.

[0092] The next dipping may comprise a coating of a plasticized Styrene Ethylene butadiene Styrene block copolymer composition obtained by solubilization of this elastomer and plasticizer (mineral oil) in a solvent. The viscosity of a solution suitable for dipping is typically within a range of 500 to 2000 cps.

[0093] The operations of coating and subsequent drying prior to any next dipping may be repeated to achieve the required thickness of SEBS and then completed with an extended drying to complete the evaporation of any trace of residual solvent. In the present example, the thickness ratio of first layer to second layer (SEBS layer) will be about 1:5.

[0094] A lubricating coating applied by dip coating would finish the glove structure. This coating may be compounded from a mixture of different ingredients that would enhance the donning of the glove: typically, a mixture of acrylate base copolymer, wax and silicone.

[0095] In this example it is envisaged that the glove would offer the following unique advantages which combine a superior mechanical resistance from the external layer made of a chemically crosslinked CR/NBR blend, which will additionally withstand mild exposure to chemicals, such as aromatic hydrocarbon solvent (for example, toluene) or ethylene chloride, which would solubilize SEBS.

[0096] This laminated glove would also be highly flexible. A modulus at 100% elongation is a good indicator of flexibility and it is expected that the glove presents a high level of flexibility and hence dexterity for the user compared with the performance of blended latex (CR/NBR) composition or any other composition made of pure CR or NBR mixture.

[0097] The core of the glove made of SEBS by solvent dip coating may also impart unique characteristics to the laminated glove while being protected by a strong external layer made from the CR/NBR blend.

[0098] SEBS dipped as a true solution also imparts the highest level of impermeability (avoiding problem of pinholes). It is impervious to cracking, from ozone or ageing condition, due to its saturated nature and contains no surfactant nor any substances that would promote hydration and impair resistivity. Such a glove would advantageously find interest in the field of insulating gloves.

[0099] In addition, such composition may offer a reduced level of accelerator which is only 20% of that of a traditional latex dipped product.

Example 2: Multilayer Composition Comprising a First Layer of SEBS with a Second Layer of a Latex Blend IR/SIS

[0100] This multilayer material comprises a first layer of SEBS (same composition to example 1), and a second layer comprising a blend of SIS (80%) and IR (20%). The thin layer may be crosslinked using a conventional sulfur crosslinking system.

[0101] The contents of all references, and published patents and patent applications cited throughout the application are hereby incorporated by reference. Those skilled in the art will recognize that the disclosure may be practiced with variations on the disclosed structures, materials, compositions and methods, and such variations are regarded as within the ambit of the disclosure.

[0102] Those skilled in the art will recognize, or be able to ascertain using no more than routine experimentation, many equivalents to the specific embodiments and methods described herein. Such equivalents are intended to be encompassed by the scope of the following claims.

[0103] It is understood that the detailed examples and embodiments described herein are given by way of example for illustrative purposes only, and are in no way considered to be limiting to the disclosure. Various modifications or changes in light thereof will be suggested to persons skilled in the art and are included within the spirit and purview of this application and are considered within the scope of the appended claims. For example, the relative quantities of the ingredients may be varied to optimize the desired effects, additional ingredients may be added, and/or similar ingredients may be substituted for one or more of the ingredients described.

[0104] Additional advantageous features and functionalities associated with the systems, methods, and processes of the present disclosure will be apparent from the appended claims. Moreover, those skilled in the art will recognize, or be able to ascertain using no more than routine experimentation, many equivalents to the specific embodiments of the disclosure described herein. Such equivalents are intended to be encompassed by the following claims.