IE66562B1

IE66562B1 - Vulcanizate activator system for rubber compositions

Info

Publication number: IE66562B1
Application number: IE419189A
Authority: IE
Inventors: Carl Ramsey Parks; Richard Michael D'sidocky; Martin Paul Cohen
Original assignee: Goodyear Tire & Rubber
Priority date: 1988-12-28
Filing date: 1989-12-28
Publication date: 1996-01-24
Also published as: KR900009701A; FI99134B; MY105906A; FI896047A0; DK668089D0; CN1062574C; CA1340497C; FI99134C; NO895244L; ATE105001T1; AR247219A1; IE894191L; NO179951C; ZA899579B; CN1043726A; CN1277210A; DK668089A; MA21696A1; PT92754A; NO895244D0

Abstract

A method is disclosed for increasing the rate of vulcanization of a rubber composition comprising adding to a sulfur vulcanizable rubber a methyl trialkyl ammonium salt of the formula: (see fig. I) wherein R1, R2, and R3 are independently alkyl radicals having 8 to 10 carbon atoms and M is selected from the group consisting of Cl, Br, CH3SO4 and HSO4. Addition of a methyl trialkyl ammonium salt of the above formula significantly increases the rate of vulcanization of the rubber. [CA1340497C]

Description

The present invention relates co the vulcanization of a sulfur curable rubber composition. More · particularly, the present invention relates co a method for increasing the race of cure of a sulfur 5 vulcanizable rubber by the addition of a methyl trialkyl ammonium salt.

The rate of cure is defined as the rate at which crosslinking and the development of the stiffness (modulus) of a rubber compound occurs. As the rubber 10 compound is heated, the properties of the rubber compound change from a soft plastic to a tough elastic material. During the curing step, crosslinks are introduced, which connect the long polymer chains of the rubber. As more cross links are introduced, the polymer chains become more firmly connected and the stiffness or modulus of the compound increases. The rate of cure is an important vulcanization parameter since it in part determines the time the compound must be cured, i.e., the cure time. In the manufacture of vulcanized rubber articles, significant cost savings can be realized through a reduction of cure cxraa. Through enhanced rates of cure, the cure time required to meet minimum states of cure can be reduced. Given the above, extensive research has been conducted in order to shorten the cure times of rubbers. Therefore, there exists a need for improved methods which enhance the rate of cure in the absence of imparting undesirable properties to the vulcanizate. -2The present invention relaxes co & method for enhancing ch® race of vulcanization of a rubber * composition comprising adding co a sulfur vulcanizable rubber a methyl trialkyl ammonium salt of the formula: ’’ R2 Θ pJ-N-R3 Μ θ ck3 i 2 3 wherein R* , R , and R are independently alkyl radicals having 8 co 10 carbon atoms and M is selected from the group consisting of Cl, Br, CH^SO^ and HSO^. In addition, there is disclosed a sulfur vulcanizable rubber composition comprising an elastomer containing olefinic unsaturation, a sulfur vulcanizing agent, an accelerator and a methyl trialkyl ammonium salt selected from the above formula.

Th® present invention relates to the use of a methyl trialkyl ammonium sale as an activator for sulfur curable rubber compositions. A particularly preferred methyl trialkyl ammonium salt is methyl trialkyl(Cg-C-jg) ammonium chloride which is commercially available under the trademark Adogen® 464 from Sherex Chemical Company of Dublin, Ohio and from Henkel Corporation, Minneapolis, Minnesota, under the trademark Aliquot© 336. Methyl trialkyl ammonium salts are generally known as phase-transfer catalysts and are described in U.S. Patent 3,992,432 which is incorporated by reference in its entirety. 1 For ease in handling, the methyl trialkyl ammonium salt may be deposited on suitable carriers. Examples -3of carriers which may be used in the present invention include silica, carbon black, alumina, kieselguhr, silica gel and calcium silicate.

Use of a methyl trialkyl asaaoniua salt does not appear co affect crosslink distribution when used in combination with primary and optionally secondary accelerators. However, along with increased cure rate, chare is usually seen an increased curative efficiency in the form of increased state or degree of cure.

The present invention may be used co cure sulfur vulcanizable rubbers or elastomers containing olefinic unsaturation. The phrase ’’rubber or elastomer containing olefinic unsaturation" Is intended co include both natural rubber .and its various raw and reclaim forms as well as various synthetic rubbers. Representative synthetic polymers are the homopolymerization products of butadiene and Its homologues and derivatives, for example, methylbutadiene, dimethylbutadiene and pentadiene as well as copolymers such as chose formed from butadiene or its homologues or derivatives with other unsaturated monomers. Among the latter are acetylenes, for example, vinyl acetylene; olefins, for example, isobutylene, which copolymerizes with isoprene co form butyl rubber; vinyl compounds, for example, acrylic acid, acrylonitrile (which polymerize with butadiene to form NBR), methacrylic acid and styrene, the latter compound polymerizing with butadiene to form SBR, as well as vinyl esters and various unsaturated aldehydes, ketones and ethers, e.g., acrolein, methyl isopropenyl ketone and vinylethyl ether., Specific examples of synthetic rubbers include neoprene (polvchloroprene), polybutadiene (including cis-1,4-polyfcratadiene), polyisoprene (including cis-1,4-polyisoprene), butyl -4rubber, copolymers of 1,3-butadiene or isoprene with monomers such as styrene, acrylonitrile and methyl methacrylate, as well as ethylene/propylene * terpolymers, also known as etnylene/propylene/diene monomer (EPDM), and in particular, ethylene/propylene/ ♦ dicyclopentadiene terpolymers» The activator used in the present invention may be added to the rubber by any conventional technique such as on a mill or in a Banbury. The amount of methyl trialkyl ammonium salt may vary widely depending on the type of rubber and other compounds present in the vulcanizable composition. Generally, the amount of methyl trialkyl ammonium salt is used in a range of from about .05 to about 5.0 phr with a range of .1 to about 1.5 phr being preferred.

Vulcanization of the rubber is generally carried out at temperatures of between about 100eC and 200°C.

Preferably, Che vulcanization is conducted at temperatures ranging from about 110°C to 180eC. Any of the usual vulcanization processes may be used such as heating In a press or mold, heating with superheated steam or hot air or in a salt bath.

In addition to the methyl trialkyl axffinonium salt, other rubber additives may also be incorporated In the sulfur vulcanizable material. The additives commonly used in rubber vulcanizates are, for example, extenders, fillers, pigments, plasticizers, zinc oxide, stearic acid, antioxidants and antiozonants.

The vulcanisation Is conducted In the presence of a sulfur vulcanizing agent. Examples of suitable sulfur vulcanizing agents include elemental sulfur (free sulfur) or sulfur donating vulcanizing agents, for *» example, an amine disulfide, polymeric polysulfide or sulfur olefin adducts. Preferably, the sulfur vulcanizing agent is elemental sulfur. -5Accelerators are used co control the time and/or temperature required for vulcanisation and co improve che properties of the vulcanizate. In on© embodiment, a single accelerator system may be used, i.e., primary accelerator. In another embodiment, combinations of two or more accelerators may be used which may consist ox a primary accelerator which is generally used in the larger amount, and a secondary accelerator which is generally used in smaller amounts in order to activate and to improve the properties of the vulcanizate. Combinations of these accelerators have been known to produce a synergistic effect of the final properties and are somewhat better chan chose produced by use of either accelerator alone. In addition, delayed action accelerators may be used which are not effected by normal processing temperatures but produce satisfactory cures at ordinary vulcanization temperatures. Suitable types of accelerators that may be used in the present invention are amines, disulfides, guanidines, thioureas, thiazoles, thiurams, sulfenamides, dithiocarbamates and xanthates.

Claims

1. CtASMS

1. A method for increasing Che race of vulcanization of a rubber composition comprising adding co a sulfur vulcanisable rubber a methyl trialkyl 5 ammonium sale of the formula: R 2 θ R~-N~R 3 M ® Cn 3 19 3 wherein Γ, R, and R are independently alkyl radicals having 8 co 10 carbon atoms and M is selected from the group consisting of Cl, Br, CH^SO^ and HSO^. 10

2. The method of claim 1 wherein at least 0.5 parts by weight per 100 parts by weight of rabber of said methyl trialkyl ammonium salt is added.

3. The method of claim 2 wherein the methyl trialkyl ammonium salt is added in an amount ranging from 0.05 to 5.0 parts by weight per 100 parts by weight of rubber. 4. c« 3 so & · The method of claim 1 wherein M is Cl or 5. The method of claim 4 wherein M is Cl. 6. The method of claim 4 wherein M is CH-SO. . 3 4 7. The raechod of claim 2 wherein said sulfur vulcanizable rubber contains an alascomer containing -7olefinic unsaturation and is selected from the group consisting of natural rubber, neoprene, polyisoprene, butyl rubber, polybutadiene, styrene-butadiene copolymer, methyl methacrylate-butadiene copolymer, isoprene-styrene copolymer, methyl methacrylate-isoprene copolymer, acrylonitrile-isoprene copolymer, acrylonitrile- butadiene copolymer, EPDM or mixtures thereof.

4. 8. The method of claim 7 wherein said sulfur vulcanizable rubber is selected from the group consisting of natural rubber, SBR, polyisoprene, or mixtures thereof,

5. 9. A sulfur vulcanizable rubber composition comprising an elastomer containing olefinic unsaturation, a vulcanizing agent, an accelerator and a methyl trialkyl ammonium salt of the formula: R 2 © ET-N-R 3 Μ θ CH 3 ι 9 3 wherein R , R~, and R are independently alkyl radicals having 8 co 10 carbon atoms and M is selected from the group consisting of Cl, Br, CH^SO^ and HSO^.

6. 10. The sulfur vulcanizable rubber composition of claim 9 wherein said methyl trialkyl ammonium salt is present in an amount of at least 0,05 parts by weight per 100 parts by weight of rubber.

7. 11. The sulfur vulcanizable rubber composition of claim 10 wherein said methyl trialkly ammonium salt is present in an amount ranging from 0.05 to 5.0 pares by weight per 100 parts by weight of rubber. -812. Th® sulfur vulcanizable rubber composition of claim 9 wherein H is Cl or CH^SQ^.

8. 13. The sulfur curable rubber composition of claim 9 wherein said elastomer is selected from the group consisting of natural rubber, neoprene, polyisoprene, butyl rubber, polybutadiene, styrene-butadiene copolymer, methyl methacrylate- butadiene copolymer, isoprene-styrene copolymer, methyl methacrylate-isoprene copolymer, acrylonitrile-isoprene copolymer, acrylonitrile-butadiene copolymer. EPDM or mixtures thereof.

9. 14. The sulfur curable rubber composition of claim 9 wherein th® sulfur vulcanizing agent is selected from the group consisting of elemental sulfur, smixie disulfide, polymeric polysulfide or sulfur olefin adducts. 13. The sulfur vulcanizable composition of claim 9 wherein the accelerator is selected from the group consisting of amines, disulfides, guanidines, thioureas, thiazoles, thiuraas, sulfanamides, dithiocarbamates, xar.thates or mixtures thereof.

10. 16. A method substantially as hereinbefore described with reference to the Exacoles.

11. 17. A comoosition substantially as hereinbefore described with reference to the Exacples.