JPH0649284A - Ethylene-acrylic ester copolymer rubber composition - Google Patents

Abstract

PURPOSE:To provide the subject profitable composition comprising ethylene- acrylic ester copolymer rubber and specific silica in a specified amount based on the rubber, and capable of realizing an ordinary temperature vulcanization. CONSTITUTION:The composition comprises 100 pts.wt. of an ethylene-acrylic ester copolymer rubber, the random copolymer of ethylene with an alkyl acrylate, 1-20 pts.wt. of silica (preferably synthetic silicic acid) having an oil absorption of >=200ml/100g and, if necessary, a filler, a plasticizer, etc.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ethylene acrylic rubber composition, and more particularly to a composition capable of preventing the generation of bubbles during normal pressure vulcanization. The composition of the present invention is used in fields where heat resistance and oil resistance are required, particularly in automobile oil cooler hoses, power steering hoses,
It is suitable for manufacturing extruded products such as radiator hoses.

[0002]

2. Description of the Related Art Conventionally, as a method of vulcanizing an unvulcanized extruded product, a method of vulcanizing with pressurized steam in a vulcanizing can, a method of melt-coating lead or a thermoplastic resin and suppressing foaming , The method of vulcanizing by its latent heat, etc. are generally used. The method using pressurized steam has the disadvantages of poor productivity and cost because it is a batch method. Further, the method by melt coating has the advantage that it can be continuously vulcanized,
Difficulties in workability and cost.

In recent years, as a means for solving such a problem,
Hot air vulcanization under normal pressure and microwave vulcanization are beginning to be used in part.

[0004]

However, these vulcanization methods under normal pressure have a problem that foaming easily occurs during vulcanization. Usually, in such a case, it is well known to use a divalent metal oxide such as calcium oxide. However, in the case of ethylene acrylic rubber, such a method cannot be used because the use of a divalent metal oxide has a significant adverse effect on unvulcanized physical properties and vulcanization properties.

The inventors of the present invention have conducted extensive studies for the purpose of solving such problems, and as a result, foamed at normal pressure without impairing the excellent various properties of ethylene acrylic rubber. We have found a composition that allows vulcanization without the need.

[0006]

The object of the present invention is to provide JIS K-510 per 100 parts by weight of ethylene acrylic rubber.
Achieved by an ethylene acrylic rubber composition, characterized in that it contains 1 to 20 parts by weight of silica having an oil absorption of 200 ml / 100 g or more, measured according to 1.

The ethylene acrylic rubber used in the present invention is a random copolymer of alkyl acrylate and ethylene, but any one generally used in industry may be used, for example, Baymac G, high viscosity product. There is Bay Mac HG (made by DuPont). The silica used in the present invention is a synthetic silicic acid having an oil absorption of 200 ml / 100 g or more. For example, Fuji Devison's Syroid 74 (oil absorption 233 ml / 100 g) and Syloid 244 (oil absorption 332 ml / 100 g) and Nippon Aerosil's Aerosil 130 (oil absorption 336 ml / 1
30g), Aerosil 300 (oil absorption 376ml / 130
g) and Aerosil 380 (oil absorption 400 ml / 130
g) etc. Silica, which is a synthetic silicic acid with an oil absorption of less than 200 ml / 100 g, which is generally used industrially,
Zeolite and the like are insufficient in preventing foaming.

In the present invention, the reason for limiting the compounding amount of the silica to the ethylene acrylic rubber to be 1 to 20 parts by weight is that when the amount is less than 1 part by weight, foaming prevention is insufficient and when the amount is more than 20 parts by weight. This is because the vulcanizate has a reduced elongation at break.

The composition of the present invention, if necessary,
Fillers, plasticizers, lubricants, antioxidants, vulcanizing agents, vulcanization accelerators and the like can be appropriately added. For example, carbon black, calcium carbonate, aluminum hydroxide or the like can be used as the filler. As the plasticizer, those which are compatible with ethylene acrylic rubber may be used, and diester-based plasticizers, polyester-based plasticizers, ether ester-based plasticizers and the like can be used. As the lubricant, low molecular weight polyethylene, fatty acids, fatty acid amines, A glycol ester of phosphoric acid or the like can be used. As the anti-aging agent, an anti-aging agent such as amine type and phenol type can be used. An amine-based vulcanizing agent can be used as the vulcanizing agent. As the vulcanization accelerator, a guanidine accelerator can be used.

When mixing the above components, a usual kneading machine for rubber, for example, a Banbury mixer, a kneader, an open roll or the like can be used.

[0011]

EXAMPLES The present invention will be specifically described below with reference to examples. In addition, the numerical value of the formulation described here shows a weight part.

Each compound is kneaded and then subjected to sheeting, and further, preforming by pressing or preforming by extrusion.

The vulcanization was performed under the predetermined conditions shown in Table 1.

The evaluation of foaming was carried out by cutting the obtained vulcanizate into small pieces and observing the cross section visually, more specifically, with a 50 × microscope.

The tensile properties of vulcanized rubber are JIS K-63.
It was evaluated by the test apparatus and test method according to 01.
As the sample, a rubber plate with a thickness of 4 mm is JIS No. 3
The one punched out with a dumbbell was used.

Examples 1 to 4 and Comparative Examples 1 to 5 In Examples (Examples of the present invention), the oil absorption was 200 ml / 1.
An appropriate amount of silica, Syloid 74 or Syloid 244, of 00 g or more is used, and in the comparative example, an unsuitable amount of silica having an oil absorption of 200 ml / 100 g or more or other adsorption desiccant, Molecular Sieve 3A or Silica Gel 80MF is used. did. The composition of them, the presence or absence of foaming during vulcanization, and the tensile properties of the vulcanizates obtained
Shown in the table.

As is clear from the table, the composition of the present invention maintains all properties in a well-balanced manner.

[0018]

As described in detail above, the ethylene acrylic rubber composition of the present invention makes it possible to realize atmospheric vulcanization, which has heretofore been unattainable, and is industrially useful.

[0019]

[Table 1]

Claims (1)

[Claims] 1. A silica having an oil absorption of 200 ml / 100 g or more per 100 parts by weight of ethylene acrylic rubber.
~ 20 parts by weight of ethylene acrylic rubber composition.