JP2002363234A - Resin crosslinking agent and crosslinked rubber obtained by using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a resin crosslinking agent improved in crosslinking speed without using any crosslinking promoter causing metal corrosion such as a halogen-containing compound or organic acid in crosslinking a rubber or epoxy resin, and to provide a crosslinked rubber obtained by using the crosslinking agent. SOLUTION: The resin crosslinking agent improved in crosslinking speed consists of a cocondensed resol-type resin made from a p-alkylphenol, another phenol bearing no substituent on the p-position and formaldehyde. The crosslinked rubber is obtained by using the resin crosslinking agent.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a resin crosslinking by a phenol / formaldehyde co-condensation resin, and more particularly to a co-condensation of a p-alkylphenol with a phenol having no substituent at the para-position and formaldehyde. The present invention relates to a resin cross-linking agent comprising a resole type resin and a cross-linked rubber using the resin cross-linking agent.

[0002]

2. Description of the Related Art A phenolic resin crosslinking agent has been conventionally used as a crosslinking agent for crosslinking rubber, and a resol type alkylphenol-formaldehyde cocondensation resin has been conventionally used. At this time, an inorganic halogen compound such as tin chloride or ferric chloride, a halogen-containing elastomer such as chloroprene rubber or chlorosulfonated polyethylene, or an organic acid is usually used as a crosslinking accelerator. In addition, halogenated alkylphenol
In some cases, a formaldehyde co-condensation resin is used.

However, when a halogen-containing compound or an organic acid is used as a cross-linking accelerator, a metal mold is corroded at the time of cross-linking molding, and a metal part is corroded when the molded article is used for an electric product. This is a major problem particularly in rubber crosslinking.

[0004]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a rubber having a high crosslinking rate without using a crosslinking accelerator which causes metal corrosion such as a halogen-containing compound or an organic acid. It is an object of the present invention to provide an improved resin crosslinking agent and a crosslinked rubber obtained by using the resin crosslinking agent.

[0005]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies for solving the problems and found that a co-condensed resole type resin of a p-alkylphenol, a phenol having no substituent at the para-position, and formaldehyde was used as a resin. It has been found that the object of the present invention can be achieved by using it as a crosslinking agent.

Hereinafter, the present invention will be described in detail. As the rubber to which the resin crosslinking agent of the present invention is applied, natural rubber,
Examples include SBR, isoprene rubber, BR, butyl rubber, EPDM, and the like. Of these, butyl rubber and EPDM are preferable. As a specific example, SBR1500 (SB manufactured by JSR Corporation)
R), Polyserbutyl 365 (butyl rubber manufactured by Policer), EP33 (EPDM manufactured by JSR), and the like.

[0007] The co-condensed resole-type resin of the present invention comprising a p-alkylphenol and a phenol having no substituent at the para-position and formaldehyde is disclosed in
5 Synthesized by a known method described in "Phenol resin" (published by Nikkan Kogyo Shimbun).

The alkyl group of the p-alkylphenol used in the present invention preferably has 1 to 20 carbon atoms, more preferably 4 to 10 carbon atoms. Specific compounds include:
p-cresol, pn-butylphenol, p-is
o-butylphenol, pt-butylphenol, p
-N-hexylphenol, p-iso-hexylphenol, pt-hexylphenol, pn-octylphenol, p-iso-octylphenol, p-
t-octylphenol and the like.

Specific examples of the phenolic compound having no substituent at the para position used in the present invention include phenol, o-cresol, m-cresol, m-ethylphenol and the like.

The amount of the phenol having no substituent at the para-position used in the present invention is preferably from 0.1 to 50% by weight of all phenols including p-alkylphenols, and from 1 to 40% by weight. % By weight is a more preferred range. If it is 0.1% by weight or less, the effect of the present invention is not recognized, and if it exceeds 50% by weight, the degree of crosslinking decreases.

The amount of the resin crosslinking agent of the present invention is not particularly limited, but is usually 1 to 30 parts by weight, preferably 3 to 25 parts by weight, per 100 parts by weight of rubber.

The crosslinked rubber of the present invention may contain an antioxidant, carbon black, various inorganic fillers, zinc white, etc., which are usually added to rubber.

The crosslinking temperature when using the resin crosslinking agent of the present invention can be applied in the same temperature range as that of the conventional resin crosslinking agent. Specifically, at about 130 to 230 ° C., an appropriate temperature according to the type of rubber is selected.

[0014]

According to the present invention, the resin crosslinking agent of the present invention has a higher speed than conventional resin crosslinking agents without using a crosslinking accelerator which causes corrosion of metals such as halogen-containing compounds or organic acids. Can crosslink rubber. In addition, a crosslinked rubber having higher hardness and higher tear strength can be obtained than when a conventional resin crosslinking agent is used.

[0015]

EXAMPLES Hereinafter, the present invention will be described in more detail with reference to examples.

[0016]

[Example 1] [Synthesis of resin cross-linking agent A] After replacing a 1-liter glass flask with nitrogen gas, 315 g of pt-octylphenol, 35 g of m-cresol, and 275 g of 37% aqueous solution of formalin were charged and slowly stirred. Meanwhile, the internal temperature was raised to about 40 ° C. Subsequently, 13.8 g of a 47% aqueous solution of caustic soda was added dropwise to start the reaction.
The reaction was performed at 5 ° C. for 1 hour. Thereafter, 67 ml of pure water and 275 ml of toluene were added to cool the reaction solution, and neutralized with hydrochloric acid. Subsequently, after performing oil-water separation, the condensed resin in the oil layer was recovered using a rotary evaporator to obtain about 350 g of a co-condensed resin (resin crosslinking agent A). [Cross-linking of butyl rubber by resin cross-linking agent A] Press-crosslinking was performed at 200 ° C. for 35 minutes with the compounding composition shown in Table 1 to obtain a cross-linked rubber. Physical properties of the crosslinked rubber were measured by the following methods, and the results are shown in Table 2 and FIG. [Measurement and evaluation methods for crosslinked rubber properties] Hardness: JIS K6253 compliant Type of test machine Type A Durometer Tear strength (N / mm): JIS K6252 compliant Specimen shape Notched angle type Measured at 180 ° C with rating rheometer, evaluated by crosslinking curve

[0017]

[Example 2] [Synthesis of resin cross-linking agent B] In the synthesis of resin cross-linking agent A for rubber in Example 1, the charged amount of pt-octylphenol was changed to 326 g, and cresol was changed to 24 g of phenol. About 350 g of a co-condensation resin (resin crosslinking agent B for rubber) was obtained in the same manner as described above. [Cross-linking of butyl rubber with resin cross-linking agent B]
Press crosslinking was performed at 35 ° C. for 35 minutes to obtain a crosslinked rubber. This crosslinked rubber was measured in the same manner as in Example 1, and the results are shown in Table 2 and FIG.

Comparative Example 1 A crosslinked rubber was obtained by press-crosslinking at 200 ° C. for 35 minutes with the composition shown in Table 1 using a tacky roll 201 which is a known resin crosslinking agent. The physical properties of this crosslinked rubber were measured in the same manner as in Example 1, and the results are shown in Table 2 and FIG.

[0019]

[Table 1] (parts by weight) Tackirole 201: Taoka Chemical Industry's resin-type alkylphenol / formalte-human co-condensation resin

[0020]

[Table 2]

[0021]

[Brief description of the drawings]

FIG. 1 shows crosslinking curves measured at 180 ° C. by the oscillating rheometers of Example 1, Example 2 and Comparative Example 1.

Claims (5)

[Claims] 1. A resin crosslinking agent comprising a co-condensed resole type resin of a p-alkylphenol, a phenol having no substituent at the para position and formaldehyde. 2. The resin crosslinking agent according to claim 1, wherein the content of the phenol having no substituent at the para position is 0.1 to 50% by weight of the total phenol. 3. The resin crosslinking agent according to claim 1, wherein the phenol having no substituent at the para position is phenol, o-cresol, or m-cresol. 4. A crosslinked rubber using the resin crosslinking agent according to claim 1. 5. The crosslinked rubber according to claim 4, wherein the crosslinked rubber is butyl rubber or EPDM.