JPS63199249A - Vulcanizable rubber compound having excellent storage stability - Google Patents

Abstract

PURPOSE:To obtain a vulcanizable rubber compound containing an elastomer containing a carboxyl group and epoxy group as crosslinkable groups, (conjugate) base as a vulcanization accelerator and triazine thiols as a stabilizer and having excellent storage stability. CONSTITUTION:(A) 100pts.wt. elastomer containing a carboxyl group and epoxy group as crosslinkable groups, (conjugate) base as a vulcanization, e.g. a copolymer of ethyl acrylate, allylglycidyl ether and methacrylic acid is blended with (B) 0.1-1pts.wt. vulcanization accelerator (e.g. quaternary ammonium salt or guanidines) which is a (conjugate) base having a base association constant of 10<-12>-10<3> at 25 deg.C in water and producing no crosslinking by reaction with a crosslinkable group of the (A) and (C) 0.01-1pts.wt., preferably 0.05-0.5pts.wt. triazine thiols (e.g. triazine trithiol) stabilizer e.g. using roller to provide the aimed composition.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a vulcanizable rubber compound with excellent storage stability. More specifically, the present invention relates to a vulcanizable rubber compound that improves the storage stability of a crosslinkable group-containing elastomer containing a vulcanization accelerator.

[Prior art] and [Problems to be solved by the invention] An elastomer containing a carboxyl group as a crosslinkable group, a glycidyl group-containing polyepoxy compound vulcanizing agent, and a polyepoxy compound having a vulcanizing agent of 10 in the range of 12 to 10 at 25°C in water. A vulcanizable rubber compound containing a vulcanization accelerator which is a base or a conjugate base which has a base dissociation constant (Kb) of -8007.This vulcanizable rubber compound has vulcanized physical properties.

Although it provides a vulcanizate with excellent heat aging resistance and compression set, it is desired to improve the storage stability of a compound containing a vulcanizing agent and a vulcanization accelerator.

As a result of various studies aimed at improving this point, the present inventors found that triazinethiols (Japanese Unexamined Patent Application Publication No. 1983-1990), which are mainly used as crosslinking agents for halogen-containing polymeric substances (elastomers and resins), 180539
No. 54-23651, No. 51-2355
3, U.S. Patent No. 2,804,450, etc.)
We have previously discovered that this problem can be effectively solved by using the stabilizer as a stabilizer (Patent Application No.
No. 7), and it has been found that this solution is equally applicable not only to elastomers containing carboxyl groups as crosslinkable groups, but also to elastomers containing carboxyl groups and epoxy groups as crosslinkable groups.

[Means for solving problems]

Therefore, the present invention provides a vulcanizable rubber compound with excellent storage stability that includes (1) an elastomer containing an epoxy group as a crosslinkable group, (2) an elastomer containing an epoxy group as a crosslinkable group; It contains a vulcanization accelerator, which is a base or conjugate base that has a base dissociation constant (Kb) and does not cause crosslinking by reaction with the crosslinkable group of the elastomer, and (3) a triazinethiol stabilizer.

As the elastomer containing a carboxyl group and an epoxy group, a copolymer obtained by copolymerizing a small amount (approximately 0.1 to 10% by weight) of a carboxyl group-containing monomer and an epoxy group-containing monomer is used. .

Examples of the carboxyl group-containing monomer include acrylic acid, methacrylic acid, crotonic acid, maleic acid, fumaric acid, itaconic acid, and monoalkyl maleate. Further, as the epoxy group-containing monomer, for example, glycidyl (meth)acrylate, vinyl glycidyl ether, allyl glycidyl ether, methacryl glycidyl ether, etc. are used.

Each of these crosslinkable group-containing monomers is vinyl chloride.

Vinylidene chloride, (meth)acrylonitrile, styrene, divinylbenzene, vinyl acetate, alkyl vinyl ether, alkyl acrylate, alkyl methacrylate, alkoxyalkyl acrylate, (poly)ethylene glycol diacrylate, hydroxyalkyl acrylate, acrylamide, α-olefin, conjugated diene It is copolymerized with at least one of various monomers such as.

Since these copolymers contain carboxyl groups and epoxy groups in their molecules, they are vulcanized by self-crosslinking through reactions between these crosslinkable groups without using a vulcanizing agent.

The base or conjugate base used as a vulcanization accelerator has a base dissociation constant (Kb) in the range of 1o-12 to 10'' at 25°C in water and can be crosslinked by reaction with the crosslinking group of the elastomer. Specifically, quaternary ammonium salts, quaternary phosnium salts, alkali metal salts of organic weak acids, guanidines and their weak acid salts, 2-
Those belonging to the categories of 13- or 4-substituted urea derivatives, aminopyridines and their weak acid salts, amine imides, cyclic amidines and their weak acid salts, and nitrones generally contain about 0.1 per 100 parts by weight of elastomer.
It is used in a proportion of ~10 parts by weight.

A more detailed explanation of the base and the conjugate base vulcanization accelerator can be found in Japanese Patent Publication No. 8007/1983.

Triazinethiols used as stabilizers in the vulcanizable rubber compound according to the present invention include triazinetrithiol and triazinedithiol.

Triazine monothiol and a partially thioesterified product thereof and a partially epoxy reactant are generally used in an amount of about 0.01 to 1 part by weight, preferably about 0.05 to 0.5 part by weight, per 100 parts by weight of the nidistomer. If the proportion is more than this, the compression set of the resulting vulcanized rubber will increase, while if the proportion is less than this, the object of the present invention cannot be achieved.

The preparation of a vulcanizable rubber compound consists of each of the above essential components as well as other additives such as reinforcing agents, fillers, anti-aging agents added as necessary, other stabilizers, plasticizers, lubricants, and processing agents. This is done by mixing auxiliary agents, etc. using commonly used mixing methods, such as roll mixing, Banbury mixing, solution mixing, etc., and the mixture is heated to a heating temperature depending on the type of elastomer used. Vulcanized by

〔Effect of the invention〕

The value of t5, which is a physical property value indicating the storage stability of the elastomer, is determined by the Mooney Scorch 1
s, and a value of 6 to 35 minutes is considered to be a measure of good storage stability, but in the vulcanizable rubber compound of the present invention, the value after being left at 40°C for 8 days is If triazine thiols are not added, the scorch time changes significantly over time, and the storage stability changes over time, whereas when triazine thiols are used, the scorch time changes over time. The present invention has the effect that a vulcanizate can be obtained in a small amount and in which the desirable physical properties inherent to the elastomer are not substantially impaired.

〔Example〕

Next, the present invention will be explained with reference to examples.

Example 1 97 parts of ethyl acrylate (weight, same below), 2.5 parts of allyl glycidyl ether and 0 parts of methacrylic acid
．． A copolymer obtained by emulsion polymerization of 5 parts of
°C: 46.5) 100 parts, FEF carbon black 5
0 parts, 0.6 parts of urea, 2 parts of cetyltrimethylammonium bromide and triazine trithiol (2,4,
6-trimercapto-s-triazine) 0.15 parts,
The mixture was kneaded using an 8-inch open roll.

Mooney scorch time (t
s) was measured (using Shimadzu 5IIV-200).

In order to determine the storage stability of the formulation, the Mooney scorch time was measured after leaving it in a constant temperature and humidity chamber at 40°C and 50% RH for 8 days.

Further, this compound was press-cured at 170°C for 10 minutes, and then post-vulcanized in a gear oven at 175°C for 4 hours. Regarding the obtained vulcanizate, JISK-630
Vulcanization physical properties and compression set (150℃, 7
0 hours) was measured. Furthermore, regarding this vulcanizate, 17
A heat aging test was conducted at 5° C. for 70 hours, and changes in various physical properties of the vulcanization were measured.

Example 2 In Example 1, the amount of triazine trithiol used was changed to 0.3 parts.

Example 3 In Example 1, instead of triazine trithiol,
Triazine D B (6-cyptylamino-1,3゜5
-triazine-2,4-dithiol) was used.

Comparative Example In Example 1, no triazine trithiol was used.

The measurement results for each of the above examples and comparative examples are as follows.

As shown in the table below.

(Margin below) Procedural amendment (part 1) December 4, 1986

Claims (1)

[Claims] 1. (1) an elastomer containing a carboxyl group and an epoxy group as crosslinkable groups, (2) 1.
The base dissociation constant (K
b) and a vulcanization accelerator which is a base or conjugate base that does not cause crosslinking by reaction with the crosslinking group of the elastomer, and (3) a triazinethiol stabilizer, which has excellent storage stability. Vulcanizable rubber compound. 2. The vulcanizable rubber compound according to claim 1, which contains triazinethiols in a proportion of about 0.01 to 1 part by weight per 100 parts by weight of elastomer.