Nonstaining antioxidant

Stabilization of Elastomers. Polyunsaturated elastomers are sensitive to oxidation. Stabili2ers are added to the elastomers prior to vulcani2ation to protect the mbber during drying and storage. Nonstaining antioxidants such as butylated hydroxytoluene (1),... 

Stabilizers. Antioxidants provide protection against UV light and thermal oxidative degradation. Hindered phenols are the most common nonstaining antioxidants. For SBR latices, two additional type of stabilizers must be used. 

Light. Ultraviolet (uv) light promotes free-radical oxidation at the mbber surface which produces discoloration and a brittle film of oxidized mbber (35). This skin cracks in random directions to form a pattern called crazing, which can be prevented by the addition of carbon black fillers or uv stabilizers. Black stocks are more resistant to uv light than are gum or light-colored stocks. Nonblack compounds require larger quantities of nonstaining antioxidants which should bloom to the surface as the surface uv stabilizers deplete. 

Cterically hindered phenols are used widely today as effective non- discoloring, nonstaining antioxidants for hydrocarbon systems, particularly rubbers and plastics. These compounds may be grouped in two broad classifications—monocyclic phenols represented by a compound such as 2,6-di-fer -butyl-4-methylphenol (I) and polycyclic phenols such as 2,2 -methylenebis(4-methyl-6-terf-butylphenol) (II). (Throughout this chapter, X represents tert-butyl). 

Antioxidant 431,449N, 445. [Uniroyal] Nonstaining antioxidant for latex, foam, moU and mechanical goods, sundries, pedymer mfg. 

Montaclere . [Monsanto] S ienated phenol nonstaining antioxidant f< NR, synthetic rubber, and latexes. 

SynoxSLT. [Neville] 2,2 Methylene bis (4 methyl 6 t butylphenol) nonstaining antioxidant for natural, S/B, BR, GR, and polyisoprene rubbers. 

Ultraviolet light initiates free radical oxidation at the exposed surface of an elastomeric product to generate a layer of oxidized rubber. Heat, moisture, or high humidity can then initiate crazing of the surface, which subsequently can be abraded off. Such degradation of the surface is more severe with nonblack stocks than with black compounds. Nonblack compounds such as white tire sidewalls thus require higher levels of nonstaining antioxidants than carbon black-loaded formulations. 

Nonstaining antioxidants This ciass of antioxidants is subdivided into four groups phosphites, hindered phenols, hindered bisphenols, and hydroquinones. Hindered bisphenols such as 4,4 -thiobis(6-r-butyl-m-cresol) are the most persistent of the four classes of material. Because of then-lower molecular weight, hindered phenols tend to be volatile. Phosphites tend to be used as synthetic rubber stabilizers, and hydroquinones such as 2,5-di-re t-amylhydroquinone are used in adhesives ... 

Chem. Desaip. Acrylonitrile copolymer latex with nonstaining antioxidant... 

Chem. Descrip. Carbor lated nitrile elastomer, nonstaining antioxidant CAS 9003-18-3... 

IR, EPDM, NBR limited sol. in BR and SBR Uses Nonstaining antioxidant and antiozonant in rubber limited sol. in syn. rubbers N-(1,4-Dimethylpentyl)-N -phenyl-p-phenylenediamine CAS 3081-01-4... 

Permanax, Nonstaining antioxidants, Akzo Nobel Chemicals Inc. 

Elastomers. Polyunsaturated elastomers are sensitive to oxidation. Stabilizers are added to the elastomers prior to vulcanization to protect the rubber during drying and storage. Nonstaining antioxidants such as buty-lated hydroxytoluene (1), 2,4-bis(octylthiomethyl)-6-methylphenol [110553-27-0], 4,4 -bis(a, a -dimethylbenzyl)diphenylamine (14), or aphosphite such as tris(nonyl-phenyl)phosphite (24) may be used in concentrations ranging from 0.01 to 0.5%. 

Vulkanox KB is a "non-discoloring antioxidant" and "nonstaining" antioxidant for light colored and transparent rubber goods based on natural and synthetic rubbers. Antioxidant properties can be improved in combination with Vulkanox MB-2 antioxidant. 

Hevastain 21 Nonstaining Antioxidant is a hindered phenolic compound which is produced by alkylating phenols with selected olefinic monomers. 

Nevastain 21 Nonstaining Antioxidant is an approved substance as defined by the following United States Food and Drug Administration regulations ... 

The use of protective agents is not necessary in EPM compounds. For EPDM compounds, antioxidants are provided, particularly if they are intended for high temperature (150°C or more) service. In black compounds (or when staining is tolerated) aromatic amines (espedally phenylene diamine derivatives) offer the best protection in peroxide cured compounds, TMQ use is recommended. In nonblack compounds, nonstaining antioxidants should be provided addition of... 

Isobutylene reacts with pora-methyl phenol to produce methylene-bis-methylbutyl phenol, a nonstaining antioxidant used in rubber compounds. 

Internal trim for automobiles may be conveniently secured by a latex adhesive which must be light colored and protected against oxidation by a nonstaining antioxidant. Some thickener and tackifier is desirable, as much of the trim is fabric and penetration through this would constitute a serious fault. Formulation IX aims at meeting these properties. 

In accordance with general experience, nonstaining antioxidants from the class of stearically hindered phenols or bisphenols are less effective. 

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