JPS5915142B2 - Compound composition for rubber mandrel - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION In a patent application filed on May 17, 1972 (Japanese Patent Application No. 54-61105, Japanese Unexamined Patent Publication No. 55-152734), the present inventors disclosed that a rubber mandrel was used during molding and vulcanization of a rubber hose. When vulcanizing a rubber hose using a rubber hose, the vulcanizing agent that migrates between the rubber mandrel and the inner rubber layer of the rubber hose is absorbed into the rubber mandrel. Prevent deterioration and cause oil leakage
We proposed a compounding composition for rubber mandrels.

However, such compounded compositions for rubber mandrels do not take into account the durability of the rubber mandrel, and although they can prevent deterioration of the inner rubber layer of the rubber hose, they have the disadvantage that the rubber mandrel deteriorates in a short period of time and has a high valency of 10. Ta.
This invention has been invented in view of the above points, and its purpose is to provide a rubber mandrel arrangement 5 which does not deteriorate the inner rubber layer of the rubber hose and cause oil leakage, and which has excellent durability of the rubber mandrel. The key is to add 10 to 50 parts by weight of an emulsion polymerization type polymer to 50 to 90 parts by weight of isobutylene, isoprene copolymer, or ethylene, propylene, diene monomer copolymer. 2 blended mixed polymers
A vulcanizate for a rubber mandrel was obtained by vulcanizing a rubber compound having a zero base material using a resin vulcanization system or a peroxide vulcanization system.

Isobutylene and isoprene copolymers include well-known isobutylene, isoprene, and rubber (hereinafter referred to as 25IIR).
Furthermore, as the ethylene, propylene, and diene monomer copolymer, ethylene, propylene, and diene monomer rubber (hereinafter referred to as EPDM) can be used.

In addition, emulsion polymerization type polymers such as styrene butadiene rubber (hereinafter referred to as SBR) and acrylonitrile butadiene rubber (hereinafter referred to as NBR) can be used as emulsion polymerization type polymers, and solution polymerization type polymers are suitable. do not have.

In addition, if isobutylene, isoprene copolymer, or ethylene, propylene, diene monomer copolymer is used alone as a polymer base material, a compound composition with excellent durability for rubber mandrels can be obtained. Since the transfer of the vulcanizing agent during vulcanization of the vulcanized rubber hose causes deterioration of the inner rubber layer on the rubber hose side, an emulsion polymerization type polymer must be mixed and this mixed polymer must be used as the base material.

That is, if the amount of isobutylene, isoprene copolymer, or ethylene, propylene, diene monomer copolymer is more than 90 parts by weight, the above-mentioned disadvantages will occur, and if it is less than 50 parts by weight, the durability as a rubber mandrel will deteriorate. Therefore, a mixed polymer blended with emulsion polymerization type polymer must be used in a range of 50 to 90 parts by weight depending on the durability of the rubber mandrel.

Furthermore, if resin vulcanization or peroxide vulcanization is not used as the vulcanization system for vulcanizing the rubber compound based on these mixed polymers, the purpose of the present invention will not be achieved no matter how limited the mixed polymers are. cannot be achieved, and the object of the present invention can only be achieved by combining a polymer and a vulcanization system.

Next, specific aspects and effects will be comparatively displayed using Examples. As a compound for rubber mandrel (A)
IIR, and those based on EPDM (comparative example) (Q
Products based on natural rubber or emulsion polymerization type polymers (Japanese Patent Application No. 54-61105) (B) Products based on mixed polymers of IIR and EPDM and emulsion polymerization type polymers (this invention) For each combination of vulcanization systems, i.e. (a) thiuram and sulfur, (b) thiazole and sulfur, (c) peroxide vulcanization, and (d) resin vulcanization, the outer diameter was determined using the following formulations. Extrusion molding of vulcanized product on 12φ rubber mandrel, leaded vulcanization (150℃
x 60 minutes vulcanization).

On the other hand, the formulation for rubber tubes cannot be changed significantly as the formulation has already been determined according to the required properties, and in general, those with NBR polymer as the base material (due to oil resistance) are used. The following combinations of thiuram-based accelerators and sulfur were tested. As a test method, an unvulcanized rubber tube with a thickness of 3.5 μ was extruded and coated on a mandrel having an outer diameter of 12φ using a crosshead extruder, and the rubber mandrel and the unvulcanized rubber tube were brought into close contact.

After that, leaded vulcanization was performed to cure the unvulcanized rubber tube, and a sample for evaluation of cracks was taken from the vulcanized tube using a No. 3 tampel, and a tensile test was performed using the JIS K63Ol method. The condition of cracks in the parallel part was determined.

In addition, the sharpness evaluation criteria are divided into the following three stages and show the results of each evaluation. 1: No cracks 2: A few cracks 3: Many cracks Also, the durability evaluation as a mandrel is as follows: Insert an unvulcanized tube with a thickness of 3.5 mm, perform steam vulcanization at 150°C for 60 minutes using the cloth clamp vulcanization method, remove the rubber mandrel after vulcanization, and bend this mandrel with a bending radius of 30φ until cracks occur. The number of times vulcanization was repeated was shown as a durability evaluation standard.

As described above, the present invention uses a mixed polymer as a base material, which is a blend of 10 to 50 parts by weight of an emulsion polymerization type polymer to 50 to 90 parts by weight of isobutylene, isoprene copolymer, or ethylene propylene and diene monomer copolymer. When a vulcanizate for rubber mandrels is obtained by vulcanization using resin vulcanization or peroxide vulcanization, the two requirements are organically combined to form a bond between the mandrel side and the inner layer of the rubber hose. It is possible to obtain a rubber mandrel that prevents migration of a vulcanizing agent between the rubber hoses, prevents oil leakage due to deterioration of the inner rubber layer of a rubber hose, and has a long life as a rubber mandrel.

Claims (1)

[Claims] 1 Isobutylene, isoprene copolymer, or ethylene, propylene, diene monomer copolymer 50-90
A rubber compound based on a mixed polymer blended with 50 to 10 parts by weight of an emulsion polymerization type polymer is used for rubber mandrels by resin vulcanization or peroxide vulcanization. A blended composition for a rubber mandrel, characterized in that a vulcanizate is obtained.