EP2052633A1

EP2052633A1 - Silicone mitten

Info

Publication number: EP2052633A1
Application number: EP08000504A
Authority: EP
Inventors: Hin Shing Ken Yeung
Original assignee: Sar Holdings International Ltd
Current assignee: Sar Holdings International Ltd
Priority date: 2007-10-27
Filing date: 2008-01-11
Publication date: 2009-04-29
Also published as: US20090106876A1; CN101416795A

Abstract

The invention relates to a silicone mitten (1) and a method of making of the silicone mitten (1). The silicone mitten (1) comprises a reinforced material. The seam between the first and second layer forming the mitten (1) is formed by curing the silicone composition.

Description

FIELD OF THE INVENTION

This invention relates to silicone gloves which comprises a reinforced material and methods of making the same. The silicone gloves may have high resistances to heat and steam and have high slip resistance.

BACKGROUND OF THE INVENTION

Gloves can be used to protect hands from harmful substances, heat, moisture, cuts, bums, or injuries. Numerous types of gloves have already been proposed, differing in shape and/or in the materials from which they are made. Nevertheless, the projective effects of the existing gloves are far from satisfactory.
Another desirable function of gloves is slip resistance. This is because people usually wear gloves to complete a task that involves holding an object that may be harmful to the hand, for example, holding a hot pot in the kitchen, taking out a burning charcoal from furnace, or removing a live electric wire. To complete the task properly, it is vital that the object can be held firmly by the gloved hand. This cannot be done if the gloves are slippery.
Because gloves are usually made of flexible materials, they are usually subject to undue deformation or even destruction when external forces are applied, which causes inconveniences to the users and shortens the lives of the gloves. It is thus desirable to provide gloves with enhanced strength and toughness so that they can better withstand the impact of external forces. Therefore, there is a need for improved gloves that can resist deformation and have enhanced mechanical properties such as tensile strength and tear resistance.

SUMMARY OF THE INVENTION

Disclosed herein are gloves that are have high resistances to heat and moisture, and have a high resistance to deformation when stretched or compressed. In one aspect, disclosed herein are gloves comprising an open end, a first layer and a second layer, the first layer and the second layer joining together at the edge to define a first pocket for receiving the thumb of a person and a second pocket for receiving the remaining fingers of the person, wherein the glove comprises a silicone composition and wherein at least one of the first layer and the second layer comprises a reinforced material.
In some embodiments, at least one of the outer surface of the first layer and the outer surface of the second layer comprises a plurality of ridges defining at least a grid.
In some embodiments, the grid comprises a plurality of cells.
In some embodiments, each of the plurality of cells is independently in the shape of a square, rhombus, rectangle, dimond, trapezium, parallelogram, circle, oval, triangle, pentagon, hexagon, or octagon.
In some embodiments, the height of the ridges ranges from about 0.2 mm to about 0.5 mm.
The glove may further comprise at least one opening through the first layer and the second layer near the open end of the glove.
In some embodiments, the first layer is substantially a mirror image of the second layer.
In another aspect, disclosed herein are processes of making a glove comprising the steps of: (a) providing a first layer and a second layer, wherein each of the first layer and the second layer comprises independently a silicone composition, and wherein at least one of the first layer and the second layer comprises a reinforced material; (b) placing the first layer and second layer in a glove shape mold comprising a lower portion, a mandrel and an upper portion, wherein the mandrel is between the first layer and second layer; and (c) curing the silicone composition in the mold at an elevated temperature to join the first layer and the second layer together at the edge to define an open end, a first pocket for receiving the thumb of a person, and a second pocket for receiving the remaining fingers of the person.
In some embodiments, the silicone composition disclosed herein comprises a silicone rubber, a liquid silicone rubber, a fluorosilicone rubber, a silicone-modified ethylene propylene rubber, a silicone polyester resin, a silicone alkyd resin, a silicone epoxy resin, or a combination thereof.
In some embodiments, the silicone composition disclosed herein further comprises a natural rubber, a synthetic rubber, a cross-linking agent, a catalyst, a filler, a colorant, a filler, a dispersant, a surfactant, a wetting agent, a coupling agent, a lubricant, an accelerator, a rheology modifier, a thickener, an adhesion promoter, a plasticizer, an age resister, an antioxidant, an anti-foaming agent, an anti-blocking agent, an anti-static agent, an anti-mildew agent, an acid acceptor, a UV stabilizer, a blowing agent, a fire retardant, a desiccant or a combination thereof.
In further embodiments, the silicone composition comprises one or more silicone rubber, at least one colorant and a cross-linking agent.
In some embodiments, the reinforced material comprises a polyester, polyamide, polyvinyl alcohol, carbon, glass, steel, polybenzoxazole, rayon or a combination thereof.
In other embodiments, the reinforced material is in the form of one or more filaments, fibers, threads, cords, sheets or fabrics.
In other embodiments, the reinforced material comprises at least one glass fiber sheet.
In further embodiments, the reinforced material comprises two glass fiber sheets, each of which is embedded separately in the first layer and the second layer.
In some embodiments, the elevated temperature is from about 180 °C to about 220 °C.
In some embodiments, the curing time of step (c) is from about 300 seconds to about 750 seconds.

BRIEF DESCRIPTION OF THE FIGURE

Figure 1A depicts a top view of an embodiment of the glove disclosed herein. Figure 1B is an enlargement of a portion the glove. Figure 1C depicts a front view of the glove. Figure 1D depicts an elevated view of the glove. Figure 1E depicts the side view of the glove. Figure 1F depicts a cross-section side view of the glove when viewing from the side of the glove. Figure 1G is an enlargement of a portion of the cross-section view depicted in Figure IF.

DESCRIPTION OF EMBODIMENTS OF THE INVENTION

In the following description, all numbers disclosed herein are approximate values, regardless whether the word "about" or "approximate" is used in connection therewith. They may vary by 1 percent, 2 percent, 5 percent, or, sometimes, 10 to 20 percent. Whenever a numerical range with a lower limit, R^L, and an upper limit, R^U, is disclosed, any number falling within the range is specifically disclosed. In particular, the following numbers within the range are specifically disclosed: R=R^L+k*(R^U-R^L), wherein k is a variable ranging from 1 percent to 100 percent with a 1 percent increment, i.e., k is 1 percent, 2 percent, 3 percent, 4 percent, 5 percent,..., 50 percent, 51 percent, 52 percent,..., 95 percent, 96 percent, 97 percent, 98 percent, 99 percent, or 100 percent. Moreover, any numerical range defined by two R numbers as defined in the above is also specifically disclosed.
Disclosed herein are gloves comprising an open end, a first layer and a second layer, wherein the first layer and the second layer join together at the edge to define a first pocket for receiving the thumb of a person and a second pocket for receiving the remaining fingers of the person, and the glove comprises a silicone composition. In some embodiments, at least one of the first layer and the second layer comprises a reinforced material.
In some embodiments, the thickness of the first layer or the second layer independently ranges from about 0.1 cm to about 5 cm, from about 0.15 cm to about 2.5 cm, from about 0.2 cm to about 1 cm, or from about 0.2 cm to about 0.5 cm.
Any reinforced material that can strengthen silicone composition can be used, including, but not limited to, polyesters, polyamides (e.g., nylons and aramid), polyvinyl alcohol, carbon, glass, steel (brass, zinc or bronze plated), polybenzoxazole, rayon, and other organic or inorganic compositions. These reinforced materials may be in the form of a filament, fiber, thread, cord, sheet or fabric. In other embodiments, the reinforced material comprises glass fibers. In further embodiments, the reinforced material is a fiber sheet comprising one or more fibers that is stable in the temperature ranges to be used. The reinforced fiber material may be nylon, polyester, aramid, acrylic, polyurethane, olefin, polylactide, fiberglass, airlaid fabrics, and the like. In certain embodiments, the reinforced glass fiber is coated with adhesion promoters and liquid silicone prior to use.
In some embodiments, the reinforced material is in the form of a sheet. In other embodiments, the sheet has a thickness from about 0.005 mm to about 3 mm, from about 0.01 mm to about 2 mm, from about 0.05 mm to about 1 mm, or from about 0.07 mm to about 0.5 mm.
In certain embodiments, each of the first layer and the second layer comprises independently a sheet of the reinforced material. In other embodiments, one of the first layer and the second layer comprises a sheet of the reinforced material. The sheet of the reinforced material may be in any convenient size and shape. In some embodiments, the sheet is substantially identical to the shape and size of the glove. In other embodiments, the sheet substantially corresponds to the shape of the glove and is slightly smaller than the size of the first layer or the second layer of the glove. In further embodiments, the sheet is substantially smaller than the size of the first layer or the second layer of the glove, embedded independently at any place in the first layer and/or the second layer. For example, if each of the first layer and the second layer is divided into three areas represented by a thumb area, a palm area, and a finger area, the sheet can be embedded at the thumb area, the palm area, the finger area, or a combination thereof.
In some embodiments, at least one of the outer surface of the first layer and the outer surface of the second layer comprises a plurality of ridges. In other embodiments, the plurality of ridges define at least a grid comprising a plurality of cells. The cells may be continuous or discontinuous. Each of the cells can be independently in any regular or irrgular shape. For examples, each of the cells can be independently in the shape of a square, rhombus, rectangle, dimond, trapezium, parallelogram, circle, oval, triangle, pentagon, hexagon, or octagon. The grid may also be in any convenient size and shape. In some embodiments, the grid is substantially identical to the shape and size of the glove. In other embodiments, the grid substantially corresponds to the shape of the glove and is slightly smaller than the size of the glove. In further embodiments, the grid is substantially smaller than the size of the glove, located at any place of the outer surface, and in any convenient shape. The outer surface can be divided into three areas such as a thumb area, a palm area, and a finger area. The grid can be located at the thumb area, the palm area, the finger area, or a combination thereof.
In certain embodiments, the height of the ridges defining the grid on the outer surface ranges from about 0.01 mm to about 10 mm, from about 0.03 mm to about 5 mm, from about 0.05 mm to about 2 mm, from about 0.08 mm to about 1 mm, from about 0.1 mm to about 0.8 mm, or from about 0.2 mm to about 0.5 mm.
In some embodiments, at least one of the inner surface of the first layer and the inner surface of the second layer comprises a plurality of ridges. In other embodiments, the plurality of ridges define at least a grid comprising a plurality of cells. The cells may be continuous or discontinuous. The cells can be independently in any shapes. For examples, each of the cells can be independently in the shape of a square, rhombus, rectangle, dimond, trapezium, parallelogram, circle, oval, triangle, pentagon, hexagon, or octagon. The grid may be in any convenient size and shape. In some embodiments, the grid is substantially identical to the shape and size of the glove. In other embodiments, the grid substantially corresponds to the shape of the glove and is slightly smaller than the size of the glove. In further embodiments, the grid is substantially smaller than the size of the glove, located at any area of the outer surface, and in any convenient shape. The inner surface can be divided into three areas such as a thumb area, a palm area, and a finger area. The grid can be located at the thumb area, the palm area, the finger area, or a combination thereof.
In certain embodiments, the height of the ridges defining the grid on the inner surface ranges from about 0.01 mm to about 3 mm, from about 0.05 mm to about 2 mm, from about 0.1 mm to about 1.5 mm, or from about 0.5 mm to about 1 mm.
In some embodiments, the glove comprises at least one opening through the first layer and/or the second layer near the open end of the glove. In other embodiments, the opening is used for hanging the glove when the glove is not in use. The opening can be in any convenient shape or size. For example, the opening can be in the shape of a circle, oval, triangle, square, rhombus, rectangle, parallelogram, pentagon, hexagon, or octagon. In further embodiments, the opening has a size from about 3 mm² to about 20 mm², from about 5 mm² to about 15 mm², or from about 7 mm² to about 10 mm².
In certain embodiments, the first layer is not a mirror image of the second layer. In other embodiments, the first layer is a substantial mirror image of the second layer. In further embodiments, the first layer is a mirror image of the second layer.
As used herein, the first layer is a "substantial mirror image" of the second layer when the area of the first layer is from about 80% to about 120%, from about 90% to about 110%, from about 95% to about 105%, from about 96% to about 104%, from about 97% to about 103%, from about 98% to about 102%, or from about 99% to about 101% of the area of the second layer; and the shape of the first layer and the shape of the 2-dimension virtual image formed by the reflection of the second layer in a plane mirror are similar or the same.
FIGS. 1A-1G depict an embodiment of the glove disclosed herein. The glove 1 comprises an open end 2, a first layer 3 and a second layer 4. The first layer 3 and the second layer 4 joins together at an edge to define a first pocket 5 and a second pocket 6. The glove 1 comprises an opening 10 near the open end 2. The outer surface of the first layer 3 comprises a plurality of outer ridges 7, which define an outer grid 8. The outer grid 8 comprises a plurality of outer cells 9. The inner surface 11 of the glove comprises a plurality of inner ridges 12, which define an inner grid (not shown). The inner grid comprises a plurality of inner cells 13. FIG. IF shows the depth of the outer cell 9 is larger than the depth of the inner cell 13 in this embodiment.
The silicone composition may comprise a silicon-containing polymer or prepolymer that can be cured or cross-linked to form a silicon-containing polymer. One of the common silicon-containing polymers is silicone. Silicone is also known as polymerized siloxanes or polysiloxanes. Some non-limiting examples of silicone include polydimethylsiloxane, polymethylhydrosiloxane, fluorosilicones, phenylmethyl-dimethyl silicones, and the like. Silicones have the chemical formula -[Si(R)₂-O]_n-, where R is one or more organic groups such as methyl, ethyl, and phenyl and n refers to the number of the repeating units in the backbone of the silicone polymer. In some embodiments, organic side groups can be used to link two or more -Si-O- backbones together. By varying the -Si-O-chain lengths, side groups, and crosslinking, silicones can be synthesized with a wide variety of properties and compositions.
Silicone generally is a flexible material that is widely used for gaskets, heat shields, fire stops, seals, cushions and insulation. Hardened silicone has a high temperature resistance (up to about 320 °C), excellent sealability, UV and ozone resistance, and excellent recovery after compression. Furthermore, silicone is extremely resilient to mechanical fatigue, meaning that the material can be flexed repeatedly without losing strength or elasticity. Silicone maintain their mechanical properties over a wide range of temperatures and the presence of hydrocarbon side chains in silicone rubbers makes these materials extremely hydrophobic. Because of its anti-sticking, low chemical reactivity, and low toxicity, silicone is an excellent choice for protective tools such as gloves.
Silicone can vary in consistency from liquid to gel to rubber to hard plastic. The most common silicone is linear polydimethylsiloxane (PDMS), which is silicone oil. Another common group of silicone materials includes silicone rubbers or resins, which are generally formed by branched and/or cage-like oligosiloxanes.
In some embodiments, the silicone composition disclosed herein comprises a silicon-containing polymer such as a silicone rubber, a liquid silicone rubber (LSR), fluorosilicone rubber, silicone-modified ethylene propylene rubber (SEP rubber), silicone polyester resin, silicone alkyd resin, silicone epoxy resin, or a combination thereof. In some embodiments, the silicone rubber disclosed herein is a one-component RTV rubber, a two-component RTV rubber, a silicone rubber compound, or a combination thereof.
In some embodiments, the silicone composition disclosed herein comprises a silicone rubber. Any conventional silicone rubber can be used herein. In some embodiments, the silicone rubber has the general formula (I):

R_aSiO_(4-a)/2 (I)

where R is a substituted or unsubstituted monovalent hydrocarbon radical having 1 to 10 carbon atoms and is a positive number having a value of from about 1.95 to about 2.05. In some embodiments, each R is independently alkyl such as methyl, ethyl, propyl, and butyl; alkenyl such as vinyl, allyl, and butenyl; aryl such as phenyl and tolyl; or substituted alkyl, alkenyl or aryl where one or more of the hydrogen atoms attached to the carbon atoms of the alkyl, alkenyl or aryl are substituted with halogen atoms, cyano, chloromethyl, chloropropyl, 3,3,3-trifluoropropyl, 2-cyanoethyl or the like. The radicals represented by R may be the same or different. In certain embodiments, a of formula (I) is 2.
In certain embodiments, the silicone rubber has the general formula (II):
wherein each of Q¹ and Q² independently is monovalent radical having one of the following formulae:

each of X, Y and Z independently is a divalent radical having one of the following formulae:

and each of n, m, and 1 is independently an integer from 0 to 10,000.
In some embodiments, the silicone rubber has formula (II) where 1 is 0 and X is divalent radical (9); and Y is divalent radical (11). In other embodiments, the silicone rubber has formula (II) where X is divalent radical (10); Y is divalent radical (9); and Z is divalent radical (11). In other embodiments, the silicone rubber has formula (II) where X is divalent radical (12); Y is divalent radical (9); and Z is divalent radical (11).
Generally, silicone rubber offers excellent resistance to extreme temperatures and can be used in a temperature range from about -55 °C to about 300 °C. In such temperature range, their tensile strength, elongation, tear strength and compression set can be superior to conventional natural or synthetic organic rubbers.
In general, silicone rubber is a highly inert material and does not react with most chemicals. Further, silicone rubber has higher resistances to ozone, UV light, heat, humidity, and other aging factors than any organic rubber. This chemical inertness makes silicone rubber the material of choice in medical applications and applications in extreme environments.
There are also many special grades and forms of silicone rubber, including: Steam resistant, metal detectable, glow-in-the-dark, electrically conductive, chemical/oil/acid/gas resistant, low smoke emitting, and flame-retardant.
In some embodiments, the silicone composition disclosed herein comprises a silicone rubber, such as general purpose silicone rubbers, one-component RTV silicone rubbers and two-component RTV silicone rubbers. Any conventional silicone rubbers known to skilled artisans can be used herein. The silicone rubber can be milled with at least one additive such as colorants and cross-linking agents to form a silicone composition. The silicone composition can then be extruded or injected into a mold or molded under pressure and then processed into silicone articles such as gloves. Generally, the machine pressure on the mold can be from about 20 Kg to about 300 Kg, from about 40 Kg to about 275 Kg, from about 50 Kg to about 250 Kg, from about 60 Kg to about 200 Kg, from about 70 Kg to about 175 Kg, or from about 80 Kg to about 160 Kg.
Optionally, heat can be applied to vulcanize or cure the silicone composition or article. Generally, the heat cure can be carried out in a two stage process at the mold to form the desired shape first, and then in a prolonged post-cure process after the article is removed from the mold. Generally, the curing temperature at the mold is from about 155 °C to about 235 °C, from about 175 °C to about 215 °C, or from about 185 °C to about 205 °C. The curing time at the mold can be from about 100 seconds to about 2000 seconds, from about 300 seconds to about 900 seconds, from about 400 seconds to about 800 seconds, or from about 450 seconds to about 600 seconds.
The post-cure temperature generally is from about 150 °C to about 300 °C, from about 160 °C to about 275 °C, from about 170 °C to about 250 °C, or from about 180 °C to about 225 °C. The post-cure time can be from about 10 minutes to about 24 hours, from about 20 minutes to about 16 hours, from about 30 minutes to about 10 hours, from about 1 hour to about 8 hours, or from about 2 hours to about 6 hours. In some embodiments, the curing temperature at the mold is from about 155 °C to about 165 °C. In other embodiments, the post-cure temperature is from about 200 °C to about 210 °C. In further embodiments, the curing time is from about 120 seconds to about 140 seconds. In still further embodiments, the post-cure time is from about 3 hours to about 5 hours.
Some non-limiting examples of suitable silicone rubbers for general purposes include KE-541-U, KE-551-U, KE-571-U, KE-581-U, KE-555-U, KE-575-U, KE-520-U, MF940U, MF950U, MF960U, and MF970U. Some non-limiting examples of suitable one-component RTV silicone rubber include KE-41, KE-42, KE-44, KE-45, KE-441, KE-445, and KE-45S. Some non-limiting examples of suitable two-component RTV silicone rubber include KE-12, KE-14, KE-17, KE-108, KE-111, KE-1222, KE-1241, KE-1414, KE-1415, KE-1416, KE-1417, KE-1314, KE-1600, KE-1603, and KE-1606. All of the above-mentioned silicone rubbers are obtainable from Shin-Etsu Chemical Co., Ltd., Tokyo, Japan.
In some embodiments, the silicone composition disclosed herein comprises a liquid silicone rubber (LSR). Any conventional LSR can be used herein. Liquid silicone rubber is a cured silicone with low compression, great stability and ability to resist extreme temperatures such as from about -55 °C to about 300 °C. A variety of liquid silicone rubbers are available with a wide range of physical properties and that can be tailored to specific applications. Liquid silicone rubber may be addition-crosslinked by hydrosilylation in the presence of a platinum catalyst to form a silicone elastomer. Liquid silicone rubber compositions may be formed by mixing four essential ingredients: a substantially linear silicone polymer, one or more reinforcing filler(s) and optionally one or more non-reinforcing filler(s), a cross-linking agent, and a hydrosilylation catalyst. The mechanical properties, such as tensile strength, elongation, tear strength, and compression set, of the liquid silicone rubber compositions may be evaluated. Silicone articles, such as silicone gloves, may be formed from the liquid silicone rubber compositions by a liquid injection molding system (LIMS). Liquid injection molding (LIM) is a process that involves an integrated system for proportioning, mixing, and dispensing a liquid resin formulation and directly injecting the liquid resin formulation into a mold which is clamped under pressure. In some embodiments, a two-part liquid silicone composition comprising a liquid silicone rubber, a catalyst, a crosslinker and optionally at least one additive is directly delivered into a mixer for homogenization. The homogenized mix is then injected directly into heated mold cavities in a period ranging from about 2 to about 30 seconds, or from about 3 to about 10 seconds. Vulcanization or curing occurs inside the mold cavities a period ranging from about 1 second to about 90 seconds, or from about 5 seconds to about 90 seconds.
Any LIMS known to skilled artisans can be used herein. In some embodiments, silicone articles, such as silicone gloves, can be prepared by a high-precision injection molding machine where all steps are automated, from mixing to molding. The automated system may save labor and time, and make it easy to produce high-quality molded articles. LIMS may provide some advantages over other polymer processing methods. For example, it may save time because the cure speed is fast and molding time can be reduced, especially when addition-cure liquid silicones are used. Furthermore, the liquid injection molding can be done at low injection pressures because the materials are liquids.
The LIMS is suitable for molding high-precision components and flashless, runnerless molding. Because molded silicone articles release easily from the molds after curing, the molding process can be automated. The system is environmentally friendly, as there are no byproducts generated during curing. With flashless and runnerless molding, there is no need to process waste material, meaning a more environmentally friendly manufacturing process.
Some non-limiting examples of suitable liquid silicone rubbers include KEG-2000-40 (A/B), KEG-2000-50 (A/B), KEG-2000-60 (A/B), KEG-2000-70 (A/B), KEG-2001-40 (A/B), KEG-2001-50 (A/B), which are suitable for fast cure, transparent, and high strength applications; KE-1950-10 (A/B), KE-1950-20 (A/B), KE-1950-30 (A/B), KE-1950-35 (A/B), KE-1950-40 (A/B), KE-1950-50 (A/B), KE-1950-60 (A/B), KE-1950-70 (A/B), which are suitable for transparent and high strength applications; KE-1935 (A/B), KE-1987 (A/B), KE-1988 (A/B), which are suitable for high transparency applications; and KE-2014-30 (A/B), KE-2014-40 (A/B), KE-2014-50 (A/B), KE-2014-60 (A/B), which are suitable for oil bleed applications. All of the above-mentioned liquid silicone rubbers are obtainable from Shin-Etsu Chemical Co., Ltd., Tokyo, Japan.
In some embodiments, the silicone composition disclosed herein comprises a fluorosilicone rubber. Any conventional fluorosilicone rubber can be used herein. Flurosilicone rubber generally has a high resistance to extreme temperatures and chemicals, and has excellent workability. Flurosilicone rubber also has an excellent resistance to solvent, oil or silicone fluid. Some non-limiting examples of suitable fluorosilicone rubbers include the FE-201-U Series for general molding purposes and the FE-301-U Series for high strength applications, all of which are obtainable from Shin-Etsu Chemical Co., Ltd., Tokyo, Japan. Other non-limiting examples of suitable fluorosilicone rubbers include FE-251-U, FE-261-U, FE-271-U, FE-351-U, FE-361-U, and FE-451-U, all of which are obtainable from Shin-Etsu Chemical Co., Ltd., Tokyo, Japan.
In some embodiments, the silicone composition disclosed herein comprises a silicone-modified ethylene propylene rubber (SEP rubber). Any conventional SEP rubber can be used herein. SEP rubber is produced by modifying ethylene propylene rubber (EPDM) with silicone. The modification improves the heat resistance, weather resistance, and low temperature characteristics of EPDM's. These properties of SEP rubber generally lie between those of EPDM and silicone rubber, but SEP rubber has the additional favorable properties of chlorine resistance and sponge foaming characteristics. In high temperature conditions over 100 °C, SEP rubber generally has a higher mechanical strength, in particular tear strength, than EPDM, and is comparable to high-strength silicone rubber. In terms of resistance to steam, hot water, acids, and alkalis, SEP rubber is generally more durable than silicone rubbers. SEP rubbers are available in several grades, e.g., general grade, heat-resistant grade, extrusion grade, flame-resistant grade, and solar grade. Some non-limiting examples of general grade SEP rubbers include SEP-1711-U and SEP-1411-U. Some non-limiting examples of heat-resistant grade SEP rubbers include SEP-1721-U, SEP-1421-U, and SEP-855B-U. One non-limiting example of extrusion grade SEP rubber includes SEP-1731-U. One non-limiting examples of flame-resistant grade SEP rubber includes SEP-363-U. One non-limiting examples of solar grade SEP rubber includes SEP-1631-U. All of the above SEP rubbers are obtainable from Shin-Etsu Chemical Co., Ltd., Tokyo, Japan.
In some embodiments, the silicone composition disclosed herein comprises a silicone polyester resin, silicone alkyd resin, or silicone epoxy resin. Any conventional silicone polyester resin, silicone alkyd resin and silicone epoxy resin known by skilled artisans can be used herein. Some non-limiting examples of silicone polyester resins include KR-5230 and KR-5230, obtainable from Shin-Etsu Chemical Co., Ltd., Tokyo, Japan. One non-limiting example of silicone alkyd resin includes KR-5206, obtainable from Shin-Etsu Chemical Co., Ltd., Tokyo, Japan. Some non-limiting examples of silicone epoxy resins include ES-1001N, ES-1002T, and ES-1023, obtainable from Shin-Etsu Chemical Co., Ltd., Tokyo, Japan.
In some embodiments, the mechanical properties and/or physical properties of the silicone composition can be modified or improved by adding one or more non-silicon containing rubber materials, such as natural rubber, synthetic rubber or a combination thereof. Some non-limiting examples of suitable synthetic rubbers include the butadiene polymers such as polybutadiene; isobutylene rubber (butyl rubber); ethylene-propylene rubber; neoprene (polychloroprene); polyisoprene; copolymers of 1,3-butadiene or isoprene with monomers such as styrene, acrylonitrile and methyl methacrylate; ethylene/propylene/diene (EPDM) rubbers such as ethylene/propylene/dicyclopentadiene terpolymers. Non-limiting examples of suitable butadiene polymers include those polymers having rubber-like properties, prepared by polymerizing butadiene alone or with one or more other polymerizable ethylenically unsaturated compounds, such as styrene, methylstyrene, methyl isopropenyl ketone and acrylonitrile. In some embodiments, the butadiene may be present in the mixture in an amount of at least 40 wt.%, based on the total amount of the polymerizable materials.
Optionally, the silicone composition may comprise one or more suitable additives such as cross-linking or curing agents, colorants (e.g., pigments and dyes), catalysts, fillers, reinforced materials, dispersants, surfactants, wetting agents, coupling agents, lubricants, accelerators, rheology modifiers, thickeners, adhesion promoters, plasticizers, age resisters, anti-oxidants, antifoaming agents, blocking agents, antistatic agents, anti-mildew agents, handling agents, acid acceptors, UV stabilizers, anti-adhesive agents, blowing agents, fire retardants, desiccants, and the like. The mechanical properties such as compression set, tensile strength and flexibility of the silicone composition disclosed herein can be adjusted by controlling, inter alia, the type and amount of the silicon-containing polymer, the curing agent, the filler and/or the reinforced material.
The cross-linking or curing agent can be a peroxide, metallic salt or a combination thereof. Some non-limiting examples of suitable cross-linking or curing agent include organic peroxides such as acyl peroxides (e.g., acetyl and benzoyl peroxides), alkyl peroxides (e.g., t-butyl peroxide and cumyl peroxide), dicarbonates, hydroperoxides (e.g., t-butyl hydroperoxide and cumyl hydroperoxide), peresters (e.g., t-butyl perbenzoate), azo compounds (e.g., 2,2'-azobisisobutyronitrile), disulfides, tetrazenes and combinations thereof.
Other non-limiting examples of suitable organic peroxide include monochlorobenzoyl peroxide, p-methylbenzyol chloride, 2,4-dichlorobenzoyl peroxide, t-butyl perbenzoate, dicumyl peroxide, 2,5-bis(t-butylperoxy)-2,5-dimethylhexane, 2,5-bis(t-butylperoxy)-2,5-dimethylhexine. Some non-limiting examples of suitable dicarbonates include dimyristyl peroxydicarbonate and dicyclododecyl peroxydicarbonate, t-butyl monoperoxycarbonates, and compounds having formula (III):
wherein each of R¹ and R² is independently alkyl having about 3 to about 10 carbon atoms.
Some suitable commercially available cross-linking or curing agents include C-1A, C-3, C-4, C-8, C-8A, C-8B, C-10, C-15, C-16, C-23, C-25A/B, and SHK-158, all of which are obtainable from Shin-Etsu Chemical Co., Ltd., Tokyo, Japan.
In some embodiments, the amount of the cross-linking or curing agent ranges from about 0.2 parts to about 5 parts, from about 0.3 parts to about 4 parts, from about 0.4 parts to about 3 parts, from about 0.5 parts to about 2.5 parts, from about 0.5 parts to about 2.5 parts, from about 0.75 parts to about 2 parts, or from about 1.25 parts to about 1.75 parts per 100 parts of the silicon composition. In other embodiments, the amount of the cross-linking or curing agent is at most about 0.5 parts, at most about 0.75 parts, at most about 1.0 part, at most about 1.5 parts, at most about 2.0 parts, or at most about 3.0 parts per 100 parts of the silicon composition. In further embodiments, the amount of the cross-linking or curing agent is at least about 0.1 parts, at least about 0.2 parts, at least about 0.3 parts, at least about 0.4 parts, at least about 0.5 parts, or at least about 0.6 parts per 100 parts of the silicon composition.
In some embodiments, the silicone composition can be cured by a conventional addition reaction curing agent. Some non-limiting examples of suitable addition reaction curing agent include organohydrogenpolysiloxanes having at least two or at least three Si-H groups in a molecule. Some non-limiting examples of suitable organohydrogenpolysiloxanes include methylhydrogenpolysiloxane and copolymers of methylhydrogenpolysiloxane and dimethylpolysiloxane. In general, the organohydrogenpolysiloxane can be blended in the silicone composition in an amount from about 0.5 moles to about 3 moles of Si-H groups per mole of alkenyl group in the silicone composition.
Generally, a catalyst can be used together with the addition reaction curing agent. Some non-limiting examples of suitable catalysts include chloroplatinic acid, alcohol-modified products of chloroplatinic acid, complexes of chloroplatinic acid with ethylene or propylene, and complexes of chloroplatinic acid with vinylsiloxane. The addition reaction catalyst can be blended to give from about 0.1 ppm to 1,000 ppm, or from about 1 ppm to about 500 ppm of platinum metal, based on the total weight of the silicone composition.
The silicone composition may include a sulfur vulcanizing agent, especially where the silicone composition comprises a natural rubber or a synthetic rubber. Examples of suitable sulfur vulcanizing agents include elemental sulfur or sulfur donating vulcanizing agents. In some embodiments, the sulfur vulcanizing agent is elemental sulfur. Other cross-linking agents may also be used.
The silicone composition may also comprise one or more colorants. Any conventional colorants may be used herein. Some non-limiting examples of suitable colorants include KE-Color BR, KE-Color W, KE-Color MB, KE-Color BL, KE-Color SB, X-93-941, and X-93-942, obtainable from Shin-Etsu Chemical Co., Ltd., Tokyo, Japan. Some non-limiting examples of suitable colorants include ZSB 336, ZSA 101, ZSZ924, ZSA101, ZSB216, ZSB630, ZSB631, ZSB632, ZSB633, and ZSB634, obtainable from Holland Colours China Ltd. The colorant can used individually or in combination with one or more other colorants to provide all possible colors, shades or hues for the silicone articles disclosed herein. Some non-limiting examples of suitable colors include red, orange, yellow, green, blue, indigo, purple, pink, silver, gold, bronze, brown, black, gray, pale champagne, white, and all known shades and hues thereof.
Optionally, the silicone composition may comprise one or more fillers. Any conventional filler for silicone compositions may be used herein. Some non-limiting examples of suitable fillers include metal oxides, metal nitrides, metal carbonates, metal silicates, metal powder, pulverized mica, aluminum hydroxide, carbon black, asbestos, glass wool, and combinations thereof. Some non-limiting examples of suitable metal oxides include silica, alumina, titania, magnesium oxide, barium oxide, cerium oxide, zinc oxide, iron oxide and the like. Some non-limiting examples of suitable metal nitrides include boron nitride, aluminum nitride, silicon nitride, silicon carbide, and the like. Some non-limiting examples of suitable metals include aluminum, copper, silver and the like. Some non-limiting examples of suitable metal carbonates include calcium carbonate, zinc carbonate and the like. Some non-limiting examples of suitable metal silicates include aluminum silicates, magnesium silicates, zinc silicates, iron silicates and the like. Some non-limiting examples of suitable carbon black include acetylene black, furnace black, channel black and the like.
In some embodiments, the filler is silica in the form of finely divided powder. The filler may be added for the purposes of modifying the properties and/or processability of the silicone composition. Some non-limiting examples of suitable silica include fumed silica, wet milled silica, powder of fused silica, finely divided quartz, diatomaceous earth, and mixtures thereof. The fumed silica or wet milled silica can be surface-treated to form hydrophobic silica. In some embodiments, the surface area of the silica filler is at least about 1 m²/g, at least about 10 m²/g, at least about 20 m²/g, at least about 30 m²/g, at least about 40 m²/g, or at least about 50 m²/g, as measured by the BET (Brunauer-Emmet-Teller) method of measuring surface area, as described by S. Brunauer, P. H. Emmett, and E. Teller, Journal of the American Chemical Society, 60, 309 (1938), which is incorporated herein by reference. In other embodiments, the surface area of the silica filler is from about 1 m²/g to about 500 m²/g, from about 2 m²/g to about 400 m²/g, from about 5 m²/g to about 300 m²/g, from about 10 m²/g to about 200 m²/g, or from about 25 m²/g to about 100 m²/g, as measured by the BET method.
The finely divided silica filler can be added to the silicone composition disclosed herein in an amount from about 1 part to about 30 parts by weight, from about 2 parts to about 15 parts by weight, or from about 3 parts to about 10 parts by weight, based on 100 parts by weight of the silicone composition.
Optionally, the silicone composition comprises a dispersant. Any dispersant that can disperse the filler uniformly in the silicone composition can be used. Some non-limiting examples of suitable dispersants include organosilazanes (e.g., hexamethylsilazane) or organosilanes.
Optionally, the silicone composition comprises a flame retardant. Some non-limiting examples of suitable flame retardants include hydrated aluminum hydroxide, zinc borate, metal silicates such as wollastonite, platinum and platinum compounds.
Optionally, the silicone composition comprises an adhesion promoter. Some non-limiting examples of suitable adhesion promoters include alkoxy silanes such as aminoalkylalkoxy silanes, epoxyalkylalkoxy silanes, for example, 3-glycidoxypropyltrimethoxysilane and, mercapto-alkylalkoxy silanes and γ-aminopropyl triethoxysilane, reaction products of ethylenediamine with silylacrylates. isocyanurates containing silicon groups such as 1,3,5-tris(trialkoxysilylalkyl) isocyanurates may additionally be used. Further suitable adhesion promoters are reaction products of epoxyalkylalkoxy silanes such as 3-glycidoxypropyltrimethoxysilane with amino-substituted alkoxysilanes such as 3-aminopropyltrimethoxysilane and optionally alkylalkoxy silanes such as methyl- trimethoxysilane. epoxyalkylalkoxy silane, mercaptoalkylalkoxy silane, and derivatives thereof.
The silicone composition may also comprise one or more accelerators. Accelerators can be used to control the time and/or temperature required for the vulcanization and to improve the properties of the vulcanizate. Suitable accelerators include, but are not limited to, amines, disulfides, guanidines, thioureas, thiazoles, thiurams, sulfenamides, dithicarbonates and zanthates. In some embodiments, the primary accelerator is a sulfenamide such as N,N-dicylohexyl-2-benzenethiazole sulfenamide. Any cobalt compound that can promote the adhesion of rubber to metal, such as stainless steel, may be used. Suitable cobalt compounds include, but are not limited to, cobalt salts of fatty acids and other carboxylic acids, such as stearic acid, palmitic, oleic, linoleic, and the like; cobalt salts of aliphatic or alicyclic carbocylic acids having 6 to 30 carbon atoms such as cobalt neodecanoate; cobalt salts of aromatic carbocylic acids such as cobalt naphthenate; cobalt halides such as cobalt chloride; and organo-cobalt-boron complexes such as MANOBOND^® 680C from OM Group, Inc., Cleveland, Ohio.
The silicone composition may be prepared by uniformly mixing the above-described components in a rubber mixer such as a two-roll mill, Banbury mixer, dough mixer or kneader and optionally effecting heat treatment under atmospheric pressure or in vacuum. In some embodiments, the silicone composition can be prepared by charging the ingredients into a kneading means such as a kneader and the mixture then kneaded at room temperature, and finally subjected to a heat treatment at about 100 °C to about 200 °C for about 15 minutes to about 8 hours. Alternatively, the ingredients can be mixed by a Banbury mixer at an elevated temperature such as about 160 °C or higher and the mixture can subsequently be cooled down to room temperature.
The silicone compositions disclosed herein can be used to prepare silicone articles by known polymer processing techniques such as extrusion, injection molding, rotational molding, and molding. In some embodiments, the silicone articles are prepared by injection molding using the silicone composition disclosed herein. In other embodiments, the silicone articles are prepared by extrusion using the silicone composition disclosed herein. In further embodiments, the silicone articles are prepared by molding using the silicone composition disclosed herein. In additional embodiments, the silicone articles are prepared by rotational molding using the silicone composition disclosed herein.
In general, injection molding is widely used for manufacturing a variety of plastic parts for various applications. In general, injection molding is a process by which a polymer is melted or softened and then injected at high pressure into a mold, which is the inverse of the desired shape, to form parts of the desired shape and size. The mold can be made from metal, such as steel and aluminum. The injection molding of polymers is described in Beaumont et al., "Successful Injection Molding: Process, Design, and Simulation," Hanser Gardner Publications, Cincinnati, Ohio (2002), which is incorporated herein by reference in its entirety.
In some embodiments, the silicone articles can be prepared from a silicone composition comprising a liquid silicone rubber (LSR) by the liquid injection molding (LIM) process. In some embodiments, the LSR can be pumped through pipelines and/or tubes to the mold equipment. In other embodiments, a two component LSR is pumped through a static mixer by a metering pump. The two component LSR generally comprises a catalyst and a reactant. The catalyst (Part A) can be introduced into the mixture prior to simultaneous with or subsequent to the addition of optional additives. The reactant (Part B) is generally an organohydrogensiloxane cross-linker which can be blended into the mixture simultaneous with or subsequent to the addition of optional additives, including crosslinking inhibitors if required. In the static mixer, the components are mixed uniformly and then transferred to a cooled metering section of the injection molding machine. In some embodiments, the ratio of Part A: Part B is from about 2:1 to about 1:2, from about 1.5:1 to about 1:1.5, from about 1.25:1 to about 1:1.25, from about 1.1:1 to about 1:1.1, or from about 1.05:1 to about 1:1.05. Other ratios may be used to alter the properties of the silicone product. In some embodiments, the ratio of Part A: Part B can be altered by reducing or increasing the amount of the filler. In other embodiments, to adjust the crosslinking properties, the ratio of Part A: Part B can be altered by increasing the amount of the catalyst such that the LSR will set faster and at lower temperatures. In further embodiments, the ratio of Part A: Part B can be altered by increasing the monomer content such that the LSR will set slower at a higher temperature. In still further embodiments, the silicone composition is cured at a temperature from about 50 °C to about 200 °C, or from about 70 °C to about 180 °C, for a suitable period of time dependent on the temperature, amount of crosslinking agents and inhibitors. In still further embodiments, the silicone composition is cured at a temperature from about 140 °C to about 160 °C.
Any reinforced material that can strengthen silicone composition can be used herein. Some non-limiting examples of suitable reinforced material include polyesters, polyamides (e.g., nylons and aramid), polyvinyl alcohol, carbon, glass, steel (brass, zinc or bronze plated), polybenzoxazole, rayon, and other organic or inorganic compositions. These rubber reinforced materials may be in the form of a filament, fiber, thread, cord, sheet or fabric. In some embodiments, the rubber reinforced material comprises glass fibers. In some embodiments, the rubber reinforced material is a fiber sheet comprising one or more fibers that is stable in the temperature ranges to be used. The reinforced fiber material may be nylon, polyester, aramid, acrylic, polyurethane, olefin, polylactide, fiberglass, airlaid fabrics, and the like. In other embodiments, the reinforced glass fiber is coated with adhesion promoters and liquid silicone prior to use.
In some embodiments, the reinforced material is embedded in the silicone composition disclosed herein. In other embodiments, the reinforced material can be in the form of a fiber sheet. When a fiber sheet is used, a non-stick plastic film may be used to separate the top and bottom molds before inserting the fiber sheet. The non-stick plastic film may be standard cellophane, plastic wrap, wax paper, MYLAR^®, polyethylene, PVC, PTFE, TEFLON^®, or the like. In further embodiments, a TEFLON^® non-stick plastic film having a thickness of about 0.05 cm is used to separate the molds.
In certain embodiments, the fiber sheets can be coated with a premixed liquid silicone. It is desirable that the premixed liquid silicone should be used immediately or refrigerated to increase its shelf life. A variety of commercially available roll coating and spray coating machines can be used. The sheet sizes can be varied according to the amounts of coated sheet required and available materials. In one embodiment, a roll of fiberglass sheet is loaded into a z-type roll coating machine and then rolled through a bath of premixed liquid silicone. The machine speed and the size of bath can be used to adjust the coating time. Coating time may range from less than 1 minute to over 1 hour. Longer coating times are required for denser fiber weaves and thicker materials. Inversely, shorter coating times may be used with thin, open weaves. In one embodiment, the coating time is from about 6 minutes to about 18 minutes, or from about 10 minutes to about 14 minutes. In another embodiment, the coating time is from about 11 minutes to about 13 minutes. The coated fiber may be dried and then cut to a desirable size for incorporation into a variety of silicone articles.
In certain embodiments, the silicone composition comprises a silicone rubber and is placed in the metering section of the injection molding machine. Subsequently, the silicone composition in the metering section can be pushed through cooled sprue and runner systems into a heated cavity where the vulcanization of the silicone composition occur in the mold to form a molded article. In other embodiments, the molded article can be further post-cured to provide the desirable mechanical, chemical and physical properties. In further embodiments, the molded article can be cleaned with water and then dried.
Extrusion is a process by which a polymer is propelled continuously along a screw through regions of high temperature and pressure where it is melted and compacted, and finally forced through a die. The extrusion of polymers is described in C. Rauwendaal, "Polymer Extrusion", Hanser Publishers, New York, NY (1986); and M.J. Stevens, "Extruder Principals and Operation," Ellsevier Applied Science Publishers, New York, NY (1985), both of which are incorporated herein by reference in their entirety.
In some embodiments, the silicone composition disclosed herein may be extrusion molded and vulcanized into a silicone article. The silicone composition disclosed herein may comprise at least one additive disclosed herein. Extrusion molding and vulcanization of the silicone rubber composition may be carried out by any generally well-known extrusion and vulcanization methods. Some non-limiting examples of vulcanization methods include atmospheric hot-air vulcanization, continuous steam vulcanization, electron beam vulcanization, UHF (ultra-high frequency) vulcanization, and LCM (liquid curing medium) vulcanization. In certain embodiments, the vulcanization occurs at about 100 °C to about 500 °C for about 1 second to about 30 minutes. In other embodiments, the molded article can be further post-cured to provide the desirable mechanical, chemical and physical properties.
Molding is generally a process by which a polymer is melted and led into a mold, which is the inverse of the desired shape, to form parts of the desired shape and size. Molding can be pressureless or pressure-assisted. The molding of polymers is described in Hans-Georg Elias "An Introduction to Plastics," Wiley-VCH, Weinhei, Germany, pp. 161-165 ( 2003), which is incorporated herein by reference.
Rotational molding is a process generally used for producing hollow plastic products. By using additional post-molding operations, complex components can be produced as effectively as other molding and extrusion techniques. Rotational molding differs from other processing methods in that the heating, melting, shaping, and cooling stages all occur after the polymer is placed in the mold, therefore no external pressure is applied during forming. The rotational molding of polymers is described in Glenn Beall, "Rotational Molding : Design, Materials & Processing," Hanser Gardner Publications, Cincinnati, Ohio (1998), which is incorporated herein by reference in its entirety.
The silicone compositions disclosed herein can be used to prepare a variety of consumer and industrial products that can be found in every room of a typical home. For example, the consumer products include kitchen products, cooking products, baking products, food storage products and the like. In general, the silicone compositions disclosed herein can be used to prepare any silicone articles for household and industrial applications. Non-limiting examples of useful silicone articles include cookwares such as steamers; lids or covers such as tagine, steamer lids, pan lids or pot lids; gloves; bakewares such as baking pans, bread pans, cupcake pans and cookie pans; measuring cups; bowls; flower poachers; pots such as melting pots; grids such as handle grids, cup holder grids, can holder grids and bottle holder grids; colanders; pads such as microwave pads; mats such as chopping board mats and sink mats; spatulas; cake molds, jelly molds (e.g., JELL-O^® molds); ice trays; storage containers; gaskets or seals; heat shields; fire stops; cushions; insulation materials and the like.
In some embodiments, silicone articles such as gloves can be prepared according to the following process which comprises the steps of (a) providing a first layer and a second layer, wherein each of the first layer and the second layer comprises independently a silicone composition, and wherein at least one of the first layer and the second layer comprises a reinforced material; (b) placing the first layer and second layer in a glove shape mold comprising a lower portion, a mandrel and an upper portion, wherein the mandrel is between the first layer and second layer; and (c) curing the silicone composition in the mold at an elevated temperature to join the first layer and the second layer together at the edge to define an open end, a first pocket for receiving the thumb of a person, and a second pocket for receiving the remaining fingers of the person. In some embodiments, one of the first layer and the second layer comprises a reinforced material. In other embodiments, both the first layer and the second layer comprise independently a reinforced material.
In other embodiments, silicone articles such as gloves can be prepared according to the following process which comprises the steps of (1) providing a silicone composition disclosed herein; (2) embedding in the silicone composition a reinforced material; and (3) effecting cross-linking of the silicone composition, wherein the reinforced material is embedded in the vulcanizable silicone composition before the cross-linking.
In further embodiments, silicone articles such as gloves can be prepared by the following process which comprises the steps of (a) providing a silicone composition; and (b) injecting the silicone composition into a mold of the silicone article disclosed herein. In other embodiments, the process further comprises the step of curing the silicone composition in the mold to form a silicone article. In further embodiments, the process further comprises the step of post-curing the silicone article.
The following examples are presented to exemplify embodiments of the invention. All numerical values are approximate. When numerical ranges are given, it should be understood that embodiments outside the stated ranges may still fall within the scope of the invention. Specific details described in each example should not be construed as necessary features of the invention.

EXAMPLES

Example 1

Example 1 is an embodiment of the silicone compositions disclosed herein. Example 1 was prepared by mixing or milling a mixture of 24.25 wt.% of ZY7821, 24.25 wt.% of QT910U, and 48.5 wt.% of ZY7817 (all of the three ingredients are silicone rubbers; obtained from Shin-Etsu Chemical Co., Ltd., Tokyo, Japan); 1.5 wt.% of SKH-158B (a cross-linking agent; obtained from Shin-Etsu Chemical Co., Ltd., Tokyo, Japan); and 1.5 wt.% of SA924, SB330, and SB400 (all are colorants and were obtained from Holland Colours NV, Apeldoorn, the Netherlands). All the wt.% amounts are based on the total weight of Example 1.

Example 2

Example 2 is an embodiment of the silicone gloves disclosed herein. Example 1 was made into a flat sheet with a thickness of about 2 mm for use in Example 2. Four glove-shaped pieces of an identical glove shape were carved out from the flat sheet, each of which weighed about 55 g. A glass-fiber sheet corresponding to the shape of the glove piece with a size slightly smaller than the glove piece was placed on top of one glove piece. Then, another glove piece was placed on top of the glass-fiber sheet, producing a first layer of the glove. Then, the same steps were repeated to produce a second layer of the glove. The molding machine is commercially available from X. L. B. Rubber Machinery Corporation, Guangzhou, Model No. XLS-1. The mold had 2 tooling cavities and each comprised an upper portion, a lower portion and a mandrel between the upper portion and the lower portion. The first layer of the glove was placed on the upper side of the mandrel; the second layer of the glove was placed on the lower portion of the mold. The upper mold and lower mold were closed and pressed towards the mandrel at a machine pressure of 150 kg and heated to about 195 °C. Example 1 was allowed to cure inside the mold for about 450 seconds. After about 450 seconds, the mold was opened, and the semi-finished glove was taken out from the mold. Excess silicone rubber of the glove was trimmed. The glove was post-cured for about 4 hours at a temperature of about 205 °C ± 4 °C. The post-cured glove was cleaned with pure water and then dried.
While the invention has been described with respect to a limited number of embodiments, the specific features of one embodiment should not be attributed to other embodiments of the invention. No single embodiment is representative of all aspects of the invention. In some embodiments, the compositions or methods may include numerous compounds or steps not mentioned herein. In other embodiments, the compositions or methods do not include, or are substantially free of, any compounds or steps not enumerated herein. Variations and modifications from the described embodiments exist. The method of making the silicone articles may be described as comprising a number of acts or steps. These steps or acts may be practiced in any sequence or order unless otherwise indicated. Finally, any number disclosed herein should be construed to mean approximate, regardless of whether the word "about" or "approximately" is used in describing the number. The appended claims intend to cover all those modifications and variations as falling within the scope of the invention.

Claims

A glove comprising an open end, a first layer and a second layer, the first layer and the second layer joining together at the edge to define a first pocket for receiving the thumb of a person and a second pocket for receiving the remaining fingers of the person, wherein the glove comprises a silicone composition and wherein at least one of the first layer and the second layer comprises a reinforced material.
The glove of claim 1, wherein the silicone composition comprises a silicone rubber, a liquid silicone rubber, a fluorosilicone rubber, a silicone-modified ethylene propylene rubber, a silicone polyester resin, a silicone alkyd resin, a silicone epoxy resin, or a combination thereof.
The glove of claim 1 or 2, wherein the silicone composition further comprises a natural rubber, a synthetic rubber, a cross-linking agent, a catalyst, a filler, a colorant, a filler, a dispersant, a surfactant, a wetting agent, a coupling agent, a lubricant, an accelerator, a rheology modifier, a thickener, an adhesion promoter, a plasticizer, an age resister, an antioxidant, an anti-foaming agent, an anti-blocking agent, an anti-static agent, an anti-mildew agent, an acid acceptor, a UV stabilizer, a blowing agent, a fire retardant, a desiccant or a combination thereof.
The glove of claim 3, wherein the silicone composition comprises one or more silicone rubber, at least one colorant and a cross-linking agent.
The glove of claim 1, wherein the reinforced material comprises a polyester, polyamide, polyvinyl alcohol, carbon, glass, steel, polybenzoxazole, rayon or a combination thereof.
The glove of claim 1, wherein the reinforced material is in the form of one or more filaments, fibers, threads, cords, sheets or fabrics.
The glove of claim 1, wherein the reinforced material comprises at least one glass fiber sheet.
The glove of claim 7, wherein the reinforced material comprises two glass fiber sheets, each of which is embedded separately in the first layer and the second layer.
The glove of claim 1, wherein at least one of the outer surface of the first layer and the outer surface of the second layer comprises a plurality of ridges defining at least a grid.
The glove of claim 9, wherein the grid comprises a plurality of cells.
The glove of claim 10, wherein each of the plurality of cells is independently in the shape of a square, rhombus, rectangle, dimond, trapezium, parallelogram, circle, oval, triangle, pentagon, hexagon, or octagon.
The glove of claim 11, wherein the height of the ridges ranges from about 0.2 mm to about 0.5 mm.
The glove of claim 1, wherein the glove comprises at least one opening through the first layer and the second layer near the open end of the glove.
The glove of claim 1, wherein the first layer is substantially a mirror image of the second layer.
A process of making a glove comprising the steps of:
(a) providing a first layer and a second layer, wherein each of the first layer and the second layer comprises independently a silicone composition, and wherein at least one of the first layer and the second layer comprises a reinforced material;

(b) placing the first layer and second layer in a glove shape mold comprising a lower portion, a mandrel and an upper portion, wherein the mandrel is between the first layer and second layer; and

(c) curing the silicone composition in the mold at an elevated temperature to join the first layer and the second layer together at the edge to define an open end, a first pocket for receiving the thumb of a person, and a second pocket for receiving the remaining fingers of the person.
The process of claim 15, wherein the silicone composition comprises a silicone rubber, a liquid silicone rubber, a fluorosilicone rubber, a silicone-modified ethylene propylene rubber, a silicone polyester resin, a silicone alkyd resin, a silicone epoxy resin, or a combination thereof.
The process of claim 16, wherein the silicone composition further comprises a natural rubber, a synthetic rubber, a cross-linking agent, a catalyst, a filler, a colorant, a filler, a dispersant, a surfactant, a wetting agent, a coupling agent, a lubricant, an accelerator, a rheology modifier, a thickener, an adhesion promoter, a plasticizer, an age resister, an antioxidant, an anti-foaming agent, an anti-blocking agent, an anti-static agent, an anti-mildew agent, an acid acceptor, a UV stabilizer, a blowing agent, a fire retardant, a desiccant or a combination thereof.
The process of any of claims 15-17, wherein the reinforced material comprises two glass fiber sheets, each of which is embedded separately in the first layer and the second layer.
The process of claim 15, wherein the elevated temperature is from about 180 °C to about 220 °C.
The process of claim 15, wherein the curing time of step (c) is from about 300 seconds to about 750 seconds.