;NORTH SAFETY PRODUCTS INC.;NORCROSS SAFETY PRODUCTS L.L.C. Assigned to NORTH SAFETY PRODUCTS INC., MORNING PRIDE MANUFACTURING, L.L.C., NORCROSS SAFETY PRODUCTS, L.L.C. These changes, however, often compromise strength, chemical resistance, or both, resulting in articles that are unsuitable for many applications. Crosslinking also increases the strength and elasticity of the rubber. In general, slow addition of the alkali metal hydroxide provides superior results and is preferred. Compound 574GY In preferred embodiments, the step of adjusting pH includes adding an alkali hydroxide to the nitrile latex. 7. 1 (the scale is thousands of pounds per square inch). As described further below, the nitrile compositions of the invention are preferably substantially free of zinc oxide. The nitrile mixture can optionally also include additives commonly used in making cured latex products, including pigments, plasticizers, processing agents, coagulants, and the like. A method according to claim 1, wherein the at least one accelerator comprises tetramethylthiuram disulfide and mercaptobenzothiazole. Although acrylonitrile is a type of cyanide, it doesn’t break up into ions once dissolved in water, which gives the type of cyanide used as poison its deadly characteristics. Vacuum cups produced with this compound are suitable for gripping marble, wood, glass, metal sheets, etc., without leaving marks or prints on the gripping surfaces. All amounts are given in parts per hundred dry rubber (phr). Nitrile rubber compositions, articles of manufacture made therefrom, and methods of making them, are disclosed. Robinson Rubber Products Company, Inc. makes no expressed or implied warranty as to any qualities, attributes, or MORNING PRIDE MANUFACTURING, L.L.C., OHIO, Free format text: The popularity of nitrile is due to its excellent resistance to petroleum products and its ability to be compounded for service over a temperature range of -22°F to 212°F. Carboxylated nitrile latexes suitable for use in the methods and compositions of the invention are known in the art, and are commercially available. Nitrile rubber, which is also called Buna-N or NBR, is an unsaturated synthetic copolymer. The invention provides nitrile rubber formulations useful for manufacturing articles having good strength and chemical resistance while being softer (i.e., having a lower elastic modulus) than many previously known rubber formulations. Typically, Wilkinson's catalyst is used to promote the hydrogenation. For example, in combination with sulfur and accelerators, carboxylated nitrile latex manufacturers frequently recommend addition of 1-10 parts of zinc oxide per 100 parts of rubber. No zinc oxide was used. The prefix cyano- is used interchangeably with the term nitrile in industrial literature. Use compound to make a product sample. Preferred cure systems for the inventive compositions include sulfur (i.e., elemental sulfur) and sulfur donors, in combination with at least one accelerator. Accordingly, surgical gloves preferably include a layer of a cured nitrile rubber of the invention having a thickness between about 3 mil and 11 mil, more preferably between about 5 mil and 10 mil. 1. NORTH SAFETY PRODUCTS L.L.C., RHODE ISLAND, Free format text: It’s a copolymer made up of a combination of acrylonitrile and butadiene molecules. The improved soft qualities of the inventive nitrile compositions make possible gloves that are thicker than conventional gloves but which are not unduly rigid or uncomfortable. RELEASE BY SECURED PARTY;ASSIGNOR:CREDIT SUISSE, ADMINISTRATIVE AGENT;REEL/FRAME:020963/0159, Owner name: Plasticizers can be added to improve the "wet gel strength" of the nitrile rubber. NITRILE (NBR) Nitrile is the most widely used elastomer in the seal industry. Gloves manufactured according to the methods of this invention preferably have a layer of a cured nitrile rubber of the invention having a thickness of between about 3 mil and about 30 mil. By eliminating the use of zinc oxide, the present invention provides a nitrile rubber that is softer than many conventional nitrile rubbers, and yet has strength and solvent-resisting qualities comparable to conventional materials, as shown in Example 2, below. The degree of hydrogenation determines the kind of vulcanization that can be applied to the polymer. Compounding and curing the rubber (which is used in latex form for, e.g., dipping to provide articles of manufacture such as gloves or condoms) with other ingredients such as curing agents, accelerators, and activators is generally performed to optimize these properties. 8. Nitrile rubber is more resistant than natural rubber to oils and acids, and has superior strength, but has inferior flexibility. Nitrile rubbers are available with an antioxidant polymerized into the polymer chain[11,12]. In certain embodiments, the protective colloid may be omitted. In preferred embodiments, the cured nitrile rubber has a 300% modulus in the range of about 400 psi to about 1100 psi, more preferably about 500 psi to about 700 psi. NORTH SAFETY PRODUCTS L.L.C.,RHODE ISLAND. HNBR is a hydrogenated version of NBR (nitrile) rubber. 1, the glove of the invention ("Soft Nitrile") is softer (i.e., has a lower elastic modulus) than a commercially-available nitrile glove ("Pdn Nitrile," a 14-mil-thick glove available from North Safety Products, product code LA142G). nitrile-butadiene-rubber 1 2 207 Nitrile Rubber (a.k.a. Trade names include Perbunan, Nipol, Krynac and Europrene. contacting the basic nitrile latex with a sulfur crosslinking agent selected from the group consisting of sulfur and sulfur donors and with an accelerator, to form a nitrile rubber. However, ionic crosslinking often increases the stiffness of an article made from the rubber. Carboxylated nitrile latexes can be chemically crosslinked in at least two ways: the butadiene subunits can be covalently crosslinked with sulfur/accelerator systems; and the carboxylated (organic acid) sites can be ionically crosslinked with metal oxides or salts. Nitriles are also resistant to air and water environments. Sodium dodecylbenzene sulfonate, when employed, is preferably present in amounts up to about 1.0 phr. The amount of stabilizer employed should be controlled to prevent foaming of the nitrile latex. Thus, the nitrile rubber compositions of the invention can be made at a cost comparable to that of conventional nitrile rubber formulations. In preferred embodiments, ammonium caseinate is present in the range of about 0.1 to about 1.0 phr, more preferably about 0.2 to about 0.4 phr. Sulfur-based cure systems arc usually retarded by the presence of acidic materials, and are often more active in the presence of alkaline materials (i.e., at higher pH). ;NORTH SAFETY PRODUCTS INC.;NORCROSS SAFETY PRODUCTS L.L.C. A preferred coagulant solution is a solution of calcium nitrate; the solution is preferably in water or an alcohol such as methanol or ethanol. ;REEL/FRAME:019215/0076, Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNOR:NORTH SAFETY PRODUCTS, INC.;REEL/FRAME:020963/0001, Owner name: In a preferred embodiment, the cured nitrile rubber composition is substantially free of divalent metal oxides. Sodium 2-ethylhexyl sulfate is preferably present in a range from about 0.01 phr to about 1.0 phr, and more preferably about 0.05 phr. The tanks are heated to 30–40 °C to facilitate the polymerization reaction and to promote branch formation in the polymer. Gloves were made from the nitrile latex prepared in Example 1, supra, by the following procedure. Butyl zimate is effective for curing of carboxylated nitrile compositions having varied, e.g., low or high acrylonitrile content, while the combination of MBT and TMTD is generally less effective for low-acrylonitrile formulations. This rubber is known for its resistance to chemicals, oils and fuels. Because several monomers capable of propagating the reaction are involved in the production of nitrile rubber the composition of each polymer can vary (depending on the concentrations of each monomer added to the polymerization tank and the conditions within the tank). [6], Also known as highly saturated nitrile (HSN), HNBR is widely known for its physical strength and retention of properties after long-term exposure to heat, oil, and chemicals. Natural rubber For example, we mix natural rubber (NR), EPDM, nitrile rubber (NBR), styrene-butadiene (SBR), polychloroprene or Neoprene (CR), butyl (IIR), and many others. In preferred embodiments, the rubber is substantially free of zinc. Next, water-based dispersions of the sulfur, butyl zimate (components of the sulfur cure), and titanium dioxide and phthalocyanine blue (pigments), were added and mixed into the latex. The purpose is to provide additional protection for the NBR during prolonged fluid service or in cyclic fluid and air exposureWhen compounding with highly reinforcing furnace . Nitrile is the shortened version of Nitrile Butadiene Rubber (NBR). NBR is used in the automotive and aeronautical industry to make fuel and oil handling hoses, seals, grommets, and self-sealing fuel tanks. Viscosity is a problem in nitrile latexes, particularly at higher pH levels, e.g., at pH above about 8.0. In another aspect, the invention provides articles of manufacture made from any of the nitrile rubber compositions of the invention. A cured nitrile rubber material having less than about 7% increase in area after 24 hour exposure to hexane is referred to herein as "chemically resistant." Nitrile is the most widely used elastomer in the seal industry. The invention further provides a cured nitrile rubber composition formed by the above-described method. Unlike polymers meant for ingestion, where small inconsistencies in chemical composition/structure can have a pronounced effect on the body, the general properties of NBR are insensitive to composition. Butyl zimate is also more active than MBT and TMTD at lower temperatures. A method of making a sulfur-cured nitrile rubber, comprising the steps of. The contents of all publications cited throughout this specification are hereby incorporated by reference in their entirety. Exemplary alkali metal hydroxides include lithium, sodium, and potassium hydroxides, with potassium hydroxide being preferred. As described above, when zinc oxide is omitted from previously known nitrile rubber compositions (which typically have a pH of 7.5-8.5), articles made from the nitrile rubber will frequently suffer from low tensile strength and decreased chemical resistance compared to nitrile rubbers which contain zinc oxide. Organic compounds … Typical for plasticizers to act a dual purpose ingredients, increase elongation, reduce hardness, improve tack; depending on the amount and type used and the rubber involved An important factor in the properties of NBR is the ratio of acrylonitrile groups to butadiene groups in the polymer backbone, referred to as the ACN content. NBR, Buna-N, and nitrile all represent the same elastomer based on a butadiene and acrylonitrile copolymer. [citation needed] Nitrile rubber is less likely to cause an allergic reaction than natural rubber. Important Note: These are Starting Point Rubber Compounding Formulations for providing guide lines only and should be confirmed by laboratory trials. The mechanical response of nitrile rubber can be tested in many different ways. The development of modern rubber materials has made possible the manufacture of a wide range of elastomeric articles having varying properties of strength and chemical resistance. For example, addition of water to a latex generally reduces the need for a protective colloid, although a thinner latex frequently results. Nitrile is not a natural form of rubber. The basic structure of an HNBR elastomer is provided in Figure 1. Use of a coagulant can result in a cured rubber having increased strength, e.g., tensile strength. In preferred embodiments, the method includes the further step of aging the nitrile rubber composition for a period of one to three days, before the composition is formed into finished rubber articles, or other use. 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Manufacture of elastomers resistance than nitrile rubber composition, comprising the steps of to employ an accelerator which not.