EP3548552A1 - Nitrile rubber products and methods of forming nitrile rubber products - Google Patents
Nitrile rubber products and methods of forming nitrile rubber productsInfo
- Publication number
- EP3548552A1 EP3548552A1 EP17792076.6A EP17792076A EP3548552A1 EP 3548552 A1 EP3548552 A1 EP 3548552A1 EP 17792076 A EP17792076 A EP 17792076A EP 3548552 A1 EP3548552 A1 EP 3548552A1
- Authority
- EP
- European Patent Office
- Prior art keywords
- nitrile rubber
- kaolin
- aluminium silicate
- μιτι
- filler
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Withdrawn
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Classifications
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- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
- C08L9/00—Compositions of homopolymers or copolymers of conjugated diene hydrocarbons
- C08L9/02—Copolymers with acrylonitrile
- C08L9/04—Latex
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
- C08K3/00—Use of inorganic substances as compounding ingredients
- C08K3/34—Silicon-containing compounds
- C08K3/346—Clay
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
- C08K5/00—Use of organic ingredients
- C08K5/0008—Organic ingredients according to more than one of the "one dot" groups of C08K5/01 - C08K5/59
- C08K5/0058—Biocides
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
- C08K2201/00—Specific properties of additives
- C08K2201/002—Physical properties
- C08K2201/005—Additives being defined by their particle size in general
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
- C08K2201/00—Specific properties of additives
- C08K2201/002—Physical properties
- C08K2201/006—Additives being defined by their surface area
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
- C08K5/00—Use of organic ingredients
- C08K5/36—Sulfur-, selenium-, or tellurium-containing compounds
- C08K5/41—Compounds containing sulfur bound to oxygen
- C08K5/42—Sulfonic acids; Derivatives thereof
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
- C08K5/00—Use of organic ingredients
- C08K5/36—Sulfur-, selenium-, or tellurium-containing compounds
- C08K5/45—Heterocyclic compounds having sulfur in the ring
- C08K5/46—Heterocyclic compounds having sulfur in the ring with oxygen or nitrogen in the ring
- C08K5/47—Thiazoles
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
- C08L2666/00—Composition of polymers characterized by a further compound in the blend, being organic macromolecular compounds, natural resins, waxes or and bituminous materials, non-macromolecular organic substances, inorganic substances or characterized by their function in the composition
- C08L2666/02—Organic macromolecular compounds, natural resins, waxes or and bituminous materials
- C08L2666/04—Macromolecular compounds according to groups C08L7/00 - C08L49/00, or C08L55/00 - C08L57/00; Derivatives thereof
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
- C08L2666/00—Composition of polymers characterized by a further compound in the blend, being organic macromolecular compounds, natural resins, waxes or and bituminous materials, non-macromolecular organic substances, inorganic substances or characterized by their function in the composition
- C08L2666/54—Inorganic substances
- C08L2666/58—SiO2 or silicates
- C08L2666/62—Clay
Definitions
- the present invention relates to nitrile rubber products.
- the present invention relates to nitrile rubber products comprising a filler.
- the present invention also relates to a method of forming nitrile rubber products.
- the present invention also relates to nitrile rubber latex compositions.
- Natural rubber is used in the formation of medical and consumer goods, for example in the formation of natural rubber gloves. Natural rubber includes polymeric long chain molecules of repeating units of isoprene.
- Latex refers to a composition which is a stable dispersion of polymer microparticles in an aqueous medium.
- Natural rubber latex compositions found in nature are a milky fluid; they can be found in some plants (for example angiosperms; including Hevea brasiliensis, Parthenium argentatum and Taraxacum kok-saghyz).
- the isoprene chains are crosslinked by vulcanisation, i.e. by the application of sulfur, peroxide or bisphenol, and heat. Vulcanisation increases the strength and elasticity of natural rubber.
- Natural rubber is useful in forming medical and consumer products where a barrier for the skin is needed, for example in gloves. However, some people have a natural rubber allergy. Persons with a particularly serious natural rubber allergy can experience anaphylactic shock on contact with natural rubber.
- Nitrile rubber was developed as an alternative to natural rubber.
- Nitrile rubber is a synthetic rubber copolymer of acrylonitrile and butadiene.
- a nitrile rubber latex composition is a stable dispersion of polymer microparticles in an aqueous medium which can form nitrile rubber (in solid form). Examples of nitrile rubber are sold under the names PerbunanTM, NipolTM, KrynacTM and EuropreneTM.
- Non-limiting examples of nitrile rubber latex compositions include: KNL830 as sold by KumhoTM Petrochemical; Synthomer 6328 and Synthomer 6330 as sold by SynthomerTM; Nantex 672 as sold by Nantex Industry Co. Ltd.; LG-Lutex 105 and LG-Lutex 120 as sold by LG ChemTM; BST 8503 S as sold by Bangkok Synthetics Co. Ltd; Polylac 580N as sold by Shin Foong Specialty and Applied Materials Co., Ltd.; and, NipolTM LX 550 and NipolTM LX 550L as sold by ZeonTM Chemicals L.P.
- nitrile rubber Some forms of nitrile rubber have the general formula:
- Nitrile butadiene rubber is a type of nitrile rubber.
- NBR is a family of unsaturated copolymers of 2-propenenitrile and butadiene monomers (for example 1 ,2-butadiene and 1 ,3-butadiene).
- the physical and chemical properties of NBR vary depending on the relative amount of nitrile. Generally, NBR is resistant to oil, fuel and other chemicals. The higher the relative amount of nitrile within NBR, the higher the resistance to oil but the lower the flexibility of the NBR.
- NBR is used to make a variety of medical and consumer goods, for example fuel and oil handling hoses, seals, grommets, fuel tanks, protective gloves, moulded goods, footwear, adhesives, sealants, sponges, expanded foams and floor mats.
- NBR can withstand temperatures from -40 to 108°C. Due to its resilience, NBR is often used to form disposable lab, cleaning, household, industrial and medical gloves. NBR is more resistant than natural rubber to oils and acids and has a superior strength. Gloves formed of NBR are more puncture- resistant than natural rubber gloves. Gloves formed of NBR are also preferred over natural rubber gloves because NBR is less likely to cause an allergic reaction. Whilst NBR has many beneficial properties in forming medical and consumer goods, for example gloves, it is formed of components derived from petrochemical components, namely, 2-propenenitrile and butadiene monomers. Petrochemical components are a finite resource, are relatively expensive and their production can contribute to global warming.
- 2- propenenitrile and butadiene monomer sources are also potential pollutants. Therefore, the present inventors considered the partial replacement of petrochemical components in NBR products. Whilst the present inventors found it desirable to reduce the petrochemical components in NBR products, they also sought to maintain the beneficial properties of the products.
- a filler is a component added to nitrile rubber which is generally inert.
- a nitrile rubber product comprising an aluminium silicate filler.
- the aluminium silicate filler has the formula:
- xAI2O3.ySiO2.zH2O where x, y and z are integers and can each be any one of 0, 1 , 2 or 3.
- the aluminium silicate filler comprises any one, two, three, four or five of: AI 2 Si 2 O 5 (OH) 4 ; AI 2 SiO 5 ; AI 2 Si 2 O 7 ; AI 6 SiO 3 ; and/or, 2AI 2 O 3 .SiO 2 , AI 4 SiO 8 .
- the aluminium silicate filler is a kaolin filler.
- nitrile rubber is nitrile butadiene rubber (NBR).
- aluminium silicate filler is milled aluminium silicate.
- the aluminium silicate filler has a maximum particle size of 10 m.
- the aluminium silicate filler has a maximum particle size of 9 ⁇ , or 8 ⁇ , or 7 ⁇ , or 6 ⁇ , or 5 ⁇ , or 4 ⁇ , or 3 ⁇ , or 2 ⁇ .
- aluminium silicate filler is a kaolin filler substantially free of nano-kaolin.
- the aluminium silicate filler is a kaolin filler substantially free of nano-kaolin, the nano-kaolin having a particle size of less than 1 ⁇ , or less than 500 nm, or less than 100 nm.
- the aluminium silicate filler is a kaolin filler substantially free of nano-kaolin in that the kaolin filler includes less than 5% by weight, or less than 1 % by weight, or less than 0.5% by weight, or less than 0.1 % by weight nano-kaolin, the nano-kaolin having a particle size of less than 1 ⁇ , or less than 500 nm, or less than 100 nm.
- the aluminium silicate filler is a kaolin filler with a BET surface area of from 10 to 18 m 2 /g; optionally, wherein the aluminium silicate filler is a kaolin filler with a BET surface area of from 14 to 16 m 2 /g.
- the maximum particle size is measured by a micromeriticsTM SediGraph III Plus.
- the aluminium silicate filler has a maximum particle size of from 50% to 90%, optionally 60%, below 2 ⁇ measured by a micromeriticsTM SediGraph III Plus.
- the nitrile rubber product further comprises a biocide.
- biocide is any one or more of:
- a 1 ,2-benzisothiazol-3(2H)-one optionally, ActicideTM B20, NipacideTM BIT20 , ProxelTM GXL, BiobanTM ULTRA BIT20, MicrocaveTM BIT, NuoseptTM BIT Technical , PromexTM 20D and/or, ColipaTM P96;
- the nitrile rubber product is a fuel or oil handling hose, a seal, a grommet, a fuel tank, a glove, a moulded good, footwear, an adhesive, a sealant, a sponge, an expanded foam or a floor mat.
- the nitrile rubber product is a glove.
- the glove is an NBR glove.
- the NBR glove has a thickness of 0.05 mm (plus or minus 10%).
- the NBR glove has a weight of 3.5 gm (plus or minus 10%). Further preferably, wherein at least 5% by weight of the nitrile rubber product is aluminium silicate filler.
- the nitrile rubber product is aluminium silicate filler.
- a method of forming a nitrile rubber product comprising the steps of:
- forming a nitrile rubber product covered former by placing a former in the mixed nitrile rubber latex composition and aluminium silicate dispersion.
- the former is shaped corresponding to the shape of the product to be formed.
- the method further comprises one, two, three, four, five or six of the steps of: passing the covered former through a warm oven, optionally at from 85 to 95°C, for from 2 to 3 minutes;
- the nitrile rubber latex composition comprises, consists of or consists essentially of: 2-propenenitrile, 1 ,2-butadiene and 1 ,3- butadiene; wherein if the nitrile rubber latex composition consists essentially of 2-propenenitrile, 1 ,2-butadiene and 1 ,3-butadiene the nitrile rubber latex composition comprises no more than 10% of other components.
- the aluminium silicate dispersion comprises from 30 to 75% aluminium silicate by weight, from 30 to 60% aluminium silicate by weight, from 35 to 55% aluminium silicate by weight, from 60 to 75%
- aluminium silicate by weight from 40 to 50% aluminium silicate by weight, or 45% aluminium silicate by weight, the balance being water.
- the aluminium silicate dispersion consists of water and aluminium silicate
- the aluminium silicate has a maximum particle size of 10 ⁇ , or 9 ⁇ , or 8 ⁇ , or 7 ⁇ , or 6 ⁇ , or 5 ⁇ , or 4 ⁇ , or 3 ⁇ , or 2 ⁇ .
- the aluminium silicate is a kaolin filler substantially free of nano-kaolin.
- the aluminium silicate is a kaolin filler substantially free of nano-kaolin, the nano-kaolin having a particle size of less than 1 ⁇ , or less than 500 nm, or less than 100 nm.
- the aluminium silicate is a kaolin filler substantially free of nano-kaolin in that the kaolin filler includes less than 5% by weight, or less than 1 % by weight, or less than 0.5% by weight, or less than 0.1 % by weight nano-kaolin, the nano-kaolin having a particle size of less than 1 ⁇ , or less than 500 nm, or less than 100 nm.
- the aluminium silicate is a kaolin filler with a BET surface area of from 10 to 18 m 2 /g; optionally, wherein the aluminium silicate filler is a kaolin filler with a BET surface area of from 14 to 16 m 2 /g.
- the BET surface area is measured by a micromeriticsTM TriStar II Plus.
- the nitrile rubber is nitrile butadiene rubber (NBR) and the nitrile rubber latex composition is a nitrile butadiene rubber (NBR) latex composition; or, wherein the nitrile rubber latex composition is
- XNBR carboxylated nitrile butadiene rubber
- the aluminium silicate dispersion has a pH of from 9 to 12.
- the aluminium silicate has the formula:
- xAI2O3.ySiO2.zH2O where x, y and z are integers and can each be any one of 0, 1 , 2 or 3.
- the aluminium silicate comprises any one, two, three, four or five of: AI 2 Si 2 O 5 (OH) 4 ; AI 2 SiO 5 ; AI 2 Si 2 O 7 ; AI 6 SiOi 3 ; and/or, 2AI 2 O 3 .SiO 2 , AI 4 SiO 8 .
- the aluminium silicate is kaolin.
- nitrile rubber latex composition for dip-forming comprising:
- aluminium silicate is milled aluminium silicate.
- the aluminium silicate has a maximum particle size of 10 ⁇ .
- the aluminium silicate has a maximum particle size of 9 ⁇ , or 8 ⁇ , or 7 ⁇ , or 6 ⁇ , or 5 ⁇ , or 4 ⁇ , or 3 ⁇ , or 2 ⁇ .
- the aluminium silicate is a kaolin filler substantially free of nano-kaolin.
- the aluminium silicate is a kaolin filler substantially free of nano-kaolin, the nano-kaolin having a particle size of less than 1 ⁇ , or less than 500 nm, or less than 100 nm.
- the aluminium silicate is a kaolin filler substantially free of nano-kaolin in that the kaolin filler includes less than 5% by weight, or less than 1 % by weight, or less than 0.5% by weight, or less than 0.1 % by weight nano-kaolin, the nano-kaolin having a particle size of less than 1 ⁇ , or less than 500 nm, or less than 100 nm.
- the aluminium silicate is a kaolin filler with a BET surface area of from 10 to 18 m 2 /g; optionally, wherein the aluminium silicate filler is a kaolin filler with a BET surface area of from 14 to 16 m 2 /g. Further preferably, wherein the BET surface area is measured by a
- the maximum particle size is measured by a
- the aluminium silicate has a maximum particle size of from 50% to 90%, optionally 60%, below 2 ⁇ measured by a
- the nitrile rubber latex comprises, or consists of, one or more of: KNL830, Synthomer 6328, Synthomer 6330, Nantex 672, LG-Lutex 105, LG-Lutex 120, BST 8503 S, Polylac 580N, NipolTM LX 550 or NipolTM LX 550L.
- the aluminium silicate has the formula:
- xAI2O3.ySiO2.zH2O where x, y and z are integers and can each be any one of 0, 1 , 2 or 3.
- the aluminium silicate comprises any one, two, three, four or five of: AI 2 Si 2 O 5 (OH) 4 ; AI 2 SiO 5 ; AI 2 Si 2 O 7 ; AI 6 SiO 3 ; and/or, 2AI 2 O 3 .SiO 2 , AI 4 SiO 8 .
- the aluminium silicate is kaolin.
- the nitrile rubber latex composition further comprises a dispersant.
- the nitrile rubber latex composition comprises 20 to 30% by weight dispersant.
- the dispersant is one or more of: SDBS (sodium dodecylbenzenesulfonate), sodium or ammonium salt of polyacrylic acid, sodium or ammonium salt of polymethacrylic acid, or a copolymer of acrylic acid with any one of: methacrylic acid, acrylamide or hydroxypropylacrylate.
- the nitrile rubber latex composition is an NBR latex composition.
- Figure 1 shows schematically a prior art method of forming NBR products, namely NBR gloves.
- Figure 2 shows schematically a method of forming NBR products according to the present invention.
- NBR products for example gloves
- a dipping method i.e. by dip-forming
- Figure 1 shows schematically a method of forming NBR products by dip- forming. Each numbered box shows a step in the method, as follows: 1 .
- NBR latex composition This composition is referred to as an NBR latex composition because it is a stable dispersion which can be used to form NBR products.
- NBR latex compositions comprise (in % by weight):
- butadiene total amount for 1 ,2-butadiene and 1 ,3- butadiene in equal molar amounts, plus or minus 1 , 2, 3, 4, 5, 10, 15, 20 or 25% (where the % refers to molar percentages)
- antioxidants and/or stabilisers include sodium dodecylbenzenesulfonate (sometimes abbreviated as SDBS) and diphenyl oxide disulphonates (for example sodium dodecyl diphenyl ether disulfonate).
- SDBS sodium dodecylbenzenesulfonate
- diphenyl oxide disulphonates for example sodium dodecyl diphenyl ether disulfonate
- the NBR latex composition is stirred for 16-24 hours before use in dipping; stirring results in maturation of the composition, ultimately reducing the solids to working levels of from 10 to 20% solids.
- the NBR latex composition is mixed with one or more stabilisers (for example KOH, ammonia and/or anionic surfactants) followed by a ZnO dispersion, a dispersant (for example, one or more of: SDBS (sodium dodecylbenzenesulfonate), sodium or ammonium salt of polyacrylic acid, sodium or ammonium salt of polymethacrylic acid, or a copolymer of acrylic acid with any one of: methacrylic acid, acrylamide or hydroxypropylacrylate), a sulfur dispersion, an
- stabilisers for example KOH, ammonia and/or anionic surfactants
- a dispersant for example, one or more of: SDBS (sodium dodecylbenzenesulfonate), sodium or ammonium salt
- accelerator dispersion for example, ZDEC (zinc
- diethyldithiocarbamate and/or ZDBC (zinc dibutyldithiocarbamate)), a ⁇ 2 dispersion and/or a colour dispersion.
- ZDBC zinc dibutyldithiocarbamate
- a coagulant covered former (from step 15 below) (for example a hand shaped former in the case of forming gloves) corresponding to the product to be formed into the mixture from step 2 at 25°C (plus or minus
- the mixture from step 2 has working levels of from 10 to 20% solids.
- a suitable coagulant is Ca(NO3)2-
- the former is typically composed of an inert ceramic material. The coagulant converts the liquid NBR latex composition into a wet-gel on the former.
- the film is made hard enough to form a beading on the cuff.
- the biocides can be: a 1 ,2-benzisothiazol-3(2H)-one; optionally,
- BIT20 MicrocaveTM BIT, NuoseptTM BIT Technical , PromexTM 20D and/or, ColipaTM P96; and/or, a 2-methyl-4-isothiazolin-3-one.
- the one or more biocides can be included in the NBR latex composition formed at step 2.
- One example coagulant is CaNO 3 at 10 to 20% by weight in water.
- the coagulant can additionally include a wetting agent at 0.05 to 0.10% by weight in water and a mould release agent.
- wetting agents include Teric 320TM as sold by HuntsmanTM Corporation Australia Pty. Ltd., Triton X-100TM as sold by DowTM Chemical and Igepal CO-630TM as sold by SolvayTM (Bangpoo) Specialty Chemicals Ltd.
- Non-limiting examples of mould release agents include a metal stearate (for example calcium stearate) at 1 to 2 % by weight.
- the general method above provides one non-limiting route to NBR products, for example gloves, formed of NBR.
- the method described with reference to Figure 1 can proceed continuously or can be stopped or paused by an operator at any particular step.
- FIG 2 in contrast to Figure 1 , shows a method of forming products according to the present invention.
- the steps in Figure 2 are identical to the steps in Figure 1 save for the addition of step 16.
- an aluminium silicate dispersion for example, a kaolin dispersion
- Aluminium silicate dispersion is added to the NBR latex composition before or during step 2, i.e. before or during stirring. Aluminium silicate dispersion
- aluminium silicate refers to chemical compounds which are derived from aluminium oxide (AI 2 O 3 ) and silicon dioxide (SiO 2 ) which may be anhydrous or hydrated, naturally occurring as minerals or synthetic. Their chemical formulae are expressed as xAI2O3.ySiO2.zH2O, where x, y and z are integers and can each be any one of 0, 1 , 2 or 3.
- This chemical formula includes the following compounds: ⁇ AI2S1O5 (AI2O3.S1O2), which occurs naturally as the minerals andalusite, kyanite and sillimanite (these three minerals each having different crystal structures).
- mineral kaolinite and is also called aluminium silicate dehydrate.
- AI2S12O7 (AI2O3.2S1O2), called metakaolinite, formed from kaolin by
- AI 6 SiO-i3 (3AI2O3.2S1O2), the mineral mullite, the only thermodynamically stable intermediate phase in the AI2O3-S1O2 system at atmospheric pressure. This also called '3:2 mullite' to distinguish it from 2AI2O3.S1O2, AI 4 Si0 8 '2:1 mullite'.
- Kaolin dispersion One type of aluminium silicate is kaolinite.
- Kaolinite is a layered silicate material with the chemical composition AI 2 Si2Os(OH) .
- Rocks that are rich in kaolinite are referred to as kaolin or china clay.
- Kaolinite is a common mineral and it is mined as kaolin around the world.
- a kaolin dispersion is added to the NBR latex
- the kaolin dispersion is stabilised by one or more dispersants (for example, one or more of: SDBS (sodium dodecylbenzenesulfonate), sodium or ammonium salt of polyacrylic acid, sodium or ammonium salt of
- SDBS sodium dodecylbenzenesulfonate
- sodium or ammonium salt of polyacrylic acid sodium or ammonium salt of
- polymethacrylic acid or a copolymer of acrylic acid with any one of:
- methacrylic acid, acrylamide or hydroxypropylacrylate such that the kaolin dispersion is stable on storage and able to suspend even in low solids NBR (for example from 13 to 15% solids) in dip-tanks without sedimentation.
- the dispersant can be adsorbed on the interface of solid particles and the surrounding liquid; this creates repulsion between particles and prevents flocculation of the particles.
- the kaolin is incorporated into the polymer matrix of the NBR products following the method of the present invention (for example as described with respect to Figure 2).
- the kaolin can be either hydrous or calcined kaolin.
- the kaolin dispersion added at step 16 comprises from 30 to 75% by weight kaolin, the balance being water. In some examples, the kaolin dispersion comprises from 30 to 60% by weight, or from 35 to 55% by weight, or from 60 to 75% by weight, or from 40 to 50% by weight, or 45% by weight kaolin, the balance being water.
- the kaolin dispersion comprises fine kaolin formed by milling.
- the fine kaolin is formed using a BuhlerTM MicroMediaTM bead mill.
- the fine kaolin has a maximum particle size of 10 ⁇ , or 9 ⁇ , or 8 ⁇ , or 7 ⁇ , or 6 ⁇ , or 5 ⁇ , or 4 ⁇ , or 3 ⁇ , or 2 ⁇ .
- at least 60% of the particles have a particle size below 2 ⁇ with a median average of 1 .0 ⁇ (plus or minus 10%).
- the particle size measurements can be obtained on a micromeriticsTM SediGraph III Plus.
- the milled kaolin can be passed through a filter with a suitably sized mesh to trap larger particles.
- the fine kaolin has a maximum particle size wherein at least 60% of the kaolin particles have a particle size below 2 ⁇ measured by a micromeriticsTM SediGraph III Plus.
- the fine kaolin is substantially free of nano-kaolin; wherein, nano- kaolin has a particle size of less than 1 ⁇ , or less than 500 nm, or less than 100 nm.
- the fine kaolin is substantially free of nano-kaolin in that the fine kaolin includes less than 5%, or less than 1 %, or less than 0.5%, or less than 0.1 % nano-kaolin by weight.
- the fine kaolin has a BET surface area of from 10 to 18 m 2 /g; optionally, the fine kaolin has a BET surface area of from 14 to 16 m 2 /g.
- the BET surface area is measured by a micromeriticsTM TriStar II Plus.
- a BET surface area of greater than 20 m 2 /g in fine kaolin indicates the presence of nano-kaolin.
- Relatively pure nano-kaolin has a BET surface area of greater than 50 m 2 /g.
- the inclusion of substantial amounts (greater than 5% by weight, or greater than 1 % by weight, or greater than 0.5% by weight, or greater than 0.1 % by weight) of nano-kaolin results in a relatively thicker latex composition which is
- the present inventors tested the inclusion of a kaolin dispersion with different particle sizes.
- the kaolin passed through a 45 ⁇ sieve.
- Such less fine kaolin when used in the kaolin dispersion at step 16 in Figure 2, did not suspend well in the NBR latex composition, causing sedimentation and disruption of movement of the glove moulds.
- the present inventors did not see these problems when the kaolin particles in the kaolin dispersion had a maximum particle size of 10 ⁇ .
- the kaolin dispersion was treated with one or more alkali metal hydroxides (sodium or potassium) and/or ammonium hydroxide providing an alkaline pH of from 9.0 to 12.0, in order for the kaolin dispersion to be compatible with alkaline NBR latex composition.
- alkali metal hydroxides sodium or potassium
- ammonium hydroxide providing an alkaline pH of from 9.0 to 12.0
- the kaolin dispersion is treated with a surfactant in order to reduce the surface tension of dispersion.
- surfactants include non-ionic, anionic and amphoteric surfactants.
- An example of a non-ionic surfactant is Teric 320TM .
- anionic surfactants include Darvan WAQTM and Rhodacal LDS-25/AP.
- the inertness of kaolin made it insoluble to acid and alkali, especially chlorine water that is sometimes used in NBR product forming methods to improve the surface finish of NBR products (for example gloves).
- the inertness of kaolin helps reduce surface defects that could potentially arise due to dissolution of filler on glove surfaces, especially on NBR gloves having 0.05mm (plus or minus 10%) thickness and/or a weight of from 2.8 to 3.5 grams/piece.
- the kaolin dispersion used according to the present invention uses fine kaolin such that it attains a significant zeta potential, that is required for a good dispersion stability.
- incorporating a suitable biocide can increase the long term stability in terms of particle size distribution.
- NBR latex composition from 100 to 160 nm particle size
- a suitable dispersant enables the intimate mixing of NBR latex composition (from 100 to 160 nm particle size) without causing undue agglomeration.
- using a suitably fine kaolin filler provides NBR products with the same or improved properties as standard NBR products, whilst reducing the reliance on petrochemical components in the NBR products.
- the fine kaolin filler is substantially free of nano-kaolin.
- the inclusion of substantial amounts (greater than 5% by weight, or greater than 1 % by weight, or greater than 0.5% by weight, or greater than 0.1 % by weight) of nano-kaolin results in a relatively thicker latex composition which is Theologically unstable.
- the kaolin dispersion, and resulting kaolin filler in the formed NBR products has the effect of reducing the amount of NBR latex composition needed to produce NBR products, for example gloves, without diminishing the effectiveness of the NBR products, for example gloves.
- the nitrile rubber product is an NBR glove.
- natural rubber medical gloves are dipped with from 28 to 40% by weight solids (in the starting material) to make gloves of different sizes with minimum thicknesses of 0.08 mm.
- the minimum thickness of the gloves can be measured, for example, according to ASTM D 3578 (Standard Specification for Rubber Examination Gloves).
- NBR gloves are made relatively thin, typically 0.05 mm (plus or minus 10%) thickness, with a typical weight of 3.5 gm/pc.
- Such relatively thin NBR gloves use a dilute starting NBR latex composition with total solids of from 14 to 16%, in the respective dip tank. With such low solids, the viscosity is too low ( ⁇ 100 centipoise [mPa.s]) to suspend relatively large kaolin particles without sedimentation in the dip tank.
- the present inventors surprisingly found that milling the kaolin so that it is fine, i.e. has a maximum particle size of 10 ⁇ , or 9 ⁇ , or 8 ⁇ , or 7 ⁇ , or 6 ⁇ , or 5 ⁇ , or 4 ⁇ , or 3 ⁇ , or 2 ⁇ , provides a more efficient suspension with limited sedimentation in the dip tank.
- at least 60% of the particles have a particle size below 2 ⁇ with a median average of 1 .0 ⁇ (plus or minus 10%).
- the particle size measurements can be obtained on a micromeriticsTM SediGraph III Plus.
- the milled kaolin can be passed through a filter with a suitably sized mesh to trap larger particles.
- the fine kaolin has a maximum particle size wherein at least 60% of the kaolin particles have a particle size below 2 ⁇ measured by a micromeriticsTM SediGraph III Plus.
- the fine kaolin is substantially free of nano-kaolin; wherein, nano- kaolin has a particle size of less than 1 ⁇ , or less than 500 nm, or less than 100 nm.
- the fine kaolin is substantially free of nano-kaolin in that the fine kaolin includes less than 5%, or less than 1 %, or less than 0.5%, or less than 0.1 % nano-kaolin by weight.
- the fine kaolin has a BET surface area of from 10 to 18 m 2 /g; optionally, the fine kaolin has a BET surface area of from 14 to 16 m 2 /g.
- the BET surface area is measured by a micromeriticsTM TriStar II Plus.
- a BET surface area of greater than 20 m 2 /g in fine kaolin indicates the presence of nano-kaolin.
- Relatively pure nano-kaolin has a BET surface area of greater than 50 m 2 /g.
- the present inventors formed an NBR latex composition with the following composition (Table 1 ): Table 1
- the NBR latex was KNL830 as sold by KumhoTM
- the NBR latex can be: Synthomer 6328 or Synthomer 6330 as sold by SynthomerTM; Nantex 672 as sold by Nantex Industry Co. Ltd.; LG-Lutex 105 and LG-Lutex 120 as sold by LG ChemTM; BST 8503 S as sold by Bangkok Synthetics Co. Ltd; Polylac 580N as sold by Shin Foong Specialty and Applied Materials Co., Ltd.; or, NipolTM LX 550 and NipolTM LX 550L as sold by ZeonTM Chemicals L.P.
- the particle sizes of the kaolin particles in the kaolin dispersion were varied to test the suitability of the NBR latex composition in forming an NBR product, namely, gloves.
- the kaolin particles in the kaolin dispersion having the components of Table 1 above had the size measurements of Table 2 below: Table 2 - Examples
- the kaolin particles in the kaolin dispersion having the components of Table 1 above had the size measurements of Table 3 below:
- samples 1 , 2, 3 and 4 of the Table 2 examples all suspended well in the NBR latex composition.
- the NBR gloves passed the following tests: ASTM 6319 (Standard Specification for Nitrile Examination Gloves for Medical Application) and EN455 (the
- the gloves passed a water-tightness test, as specified in method EN455-Part 1 with AQL 1 .5 as well as ASTM D6319-10 with AQL 2.5.
- NBR gloves formed using these NBR latex compositions were not well formed and did not pass the following tests: ASTM 6319 (Standard Specification for Nitrile
- the gloves did not pass a water-tightness test, as specified in method ASTM D6319-10 with AQL 2.5.
- the kaolin of the kaolin dispersions was substantially free of nano-kaolin, nano- kaolin having a particle size of less than 1 ⁇ .
- the BET surface area of the dry kaolin used to make the kaolin dispersions in both the examples of Table 2 and the comparative examples of Table 3 was from 14 to 16 m 2 /g.
- a BET surface area of greater than 20 m 2 /g indicates the presence of nano-kaolin.
- Relatively pure nano-kaolin has a BET surface area of greater than 50 m 2 /g.
- the present inventors discovered that the presence of a substantial amount of nano-kaolin (e.g. where the BET surface area of the dry kaolin used to make the kaolin dispersion is greater than 20 m 2 /g) results in a relatively thicker latex composition which is
- kaolin in some embodiments, from 5 to 10 parts by dry weight kaolin is used as a filler in nitrile gloves having a thickness of 0.05 mm (plus or minus 10%), with a typical weight of 3.5 gm (plus or minus 10%).
- the amount of kaolin can be increased if the glove thickness increases, for example 4 gm, 6 gm gloves.
- the median particle size of the kaolin, in the kaolin dispersion used with 4 gm and 6 gm gloves, is from 0.7 to 1 .0 ⁇ .
- the milled aluminium silicate can be any one, two, three or more of: AI 2 SiO 5 (AI 2 O 3 .SiO 2 ); AI 2 Si 2 O 5 (OH) 4 (AI 2 O3-2SiO2-2H 2 O); AI 2 Si 2 O 7 (AI 2 O 3 .2SiO 2 ); AI 6 SiO 13 (3AI 2 O 3 .2SiO 2 ); and/or, 2AI 2 O 3 .SiO 2 , AI 4 SiO 8 .
Abstract
Description
Claims
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GB1620319.2A GB2557215A (en) | 2016-11-30 | 2016-11-30 | Nitrile rubber products and methods of forming nitrile rubber products |
PCT/EP2017/077951 WO2018099674A1 (en) | 2016-11-30 | 2017-11-01 | Nitrile rubber products and methods of forming nitrile rubber products |
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EP (1) | EP3548552A1 (en) |
CN (1) | CN110121524A (en) |
GB (1) | GB2557215A (en) |
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MY196386A (en) * | 2019-05-23 | 2023-03-28 | Top Glove Int Sdn Bhd | Elastomeric Article |
CN113068900B (en) * | 2021-03-23 | 2022-05-24 | 泉州华光职业学院 | Preparation method of natural tea seed cake synthetic insole board |
CN114381130B (en) * | 2021-04-16 | 2023-04-28 | 南京聚隆科技股份有限公司 | Environment-friendly low-hardness high-resilience thermoplastic elastomer and preparation method thereof |
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US3943192A (en) * | 1968-03-05 | 1976-03-09 | Polysar Limited | Elastomeric blends |
US20070252115A1 (en) * | 2006-04-28 | 2007-11-01 | Arehart Kelly D | Thermochromic elastic articles |
JP5101145B2 (en) * | 2007-03-27 | 2012-12-19 | 株式会社アスクテクニカ | Joint sheet |
PL221843B1 (en) * | 2012-11-30 | 2016-06-30 | Gambit Lubawka Spółka Z Ograniczoną Odpowiedzialnością | Formulation for the sealing plates |
CN103613796A (en) * | 2013-10-28 | 2014-03-05 | 安徽祈艾特电子科技有限公司 | Oil-resistant anticorrosive capacitor rubber sealing ring and making method thereof |
CN103642426A (en) * | 2013-11-25 | 2014-03-19 | 简玉君 | Heat resistant and oil resistant rubber adhesive |
CN103897227B (en) * | 2014-04-01 | 2016-02-24 | 安徽金科橡塑制品有限公司 | A kind of mildew-resistant water proof rubber sealing-ring and preparation method thereof |
KR101465450B1 (en) * | 2014-05-27 | 2014-11-27 | (주)하이코리아 | Rubber foam adiabatic material and manufacturing method thereof |
CN105237841B (en) * | 2014-07-11 | 2018-07-27 | 上海赋瑞密封材料有限公司 | A kind of resistance to refrigerant is without asbestos seal plank and preparation method thereof |
CN104371213A (en) * | 2014-10-23 | 2015-02-25 | 周修君 | Bifacial-skinning rubber plastic flame-retardant thermal-insulation board and preparation method thereof |
CN104610597A (en) * | 2015-01-26 | 2015-05-13 | 安徽国华电缆集团有限公司 | Modified butadiene-acrylonitrile rubber sheath material for cable and preparation method for modified butadiene-acrylonitrile rubber sheath material |
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CN105566820A (en) * | 2015-12-30 | 2016-05-11 | 崇夕山 | Shaft end O-shaped permanent compression set resisting rubber sealing ring |
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CN110121524A (en) | 2019-08-13 |
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