JPH06228326A - Compounded rubber of improved processability - Google Patents

Abstract

PURPOSE:To provide a rubber free from cold flow and deformation and improved in processability either by heat-treating an unvulcanized compounded rubber into a semi-vulcanized compounded rubber or by mixing a semi- vulcanized compounded rubber with an unvulcanized compounded rubber of the same recipe. CONSTITUTION:An unvulcanized compounded rubber prepared by milling a stock rubber with various compounding additives is heat-treated to form a semi-vulcanized compounded rubber, or this is mixed with an unvulcanized compounded rubber of the same recipe. The semi-vulcanized compounded rubber can of course be used as such as the material, or according to the recipe of the unvulcanized compounded rubber, it is used in combination with a non-semi- vulcanized compounded rubber of the same recipe. The mixing ratio is suitably determined according to the recipe, the molding process, the shape of a product, etc. Although the vulcanization is usually performed by heating the compounded rubber to 110-170 deg.C under pressure, the semi-vulcanization is performed at 100-140 deg.C at which the compounded rubber does not undergo a complete crosslinking reaction. Therefore, the rubber is processable.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention has improved workability of unvulcanized rubber.
The present invention relates to an unvulcanized compounded rubber suitable for rubber used as an industrial rubber part such as an oil cooler hose, a power steering hose or a roll.

[0002]

2. Description of the Related Art To manufacture a rubber product, first, an unvulcanized compounded rubber is obtained by kneading a raw material rubber with various compounding agents such as a filler and a vulcanizing agent. These unvulcanized compounded rubbers are molded by extrusion molding or die molding, and then vulcanized to produce rubber products. For example, in a rubber hose used as an automobile part, an unvulcanized compound rubber is extruded by an extruder to form an inner tube rubber, and if necessary, at least one reinforcing layer is provided on the outer circumference of the inner tube rubber, Further, it is manufactured by coating an outer tube rubber as necessary and vulcanizing it. Further, this type of rubber hose is required to have stable strength, and for this reason, it is necessary that the inner diameter and the wall thickness are kept constant. Therefore, this type of rubber hose is generally manufactured by using a mandrel, and a flexible rubber or resin mandrel is used for the mandrel in order to continuously manufacture a large amount of long rubber hoses.

A general method for manufacturing a rubber hose containing a pressure resistant reinforcing thread using a mandrel will be described. As shown in FIG.
Is extruded to the extruder 4, and unvulcanized compounded rubber is extruded onto the outer periphery of the mandrel 1 to form the inner tube rubber 7. The unvulcanized compounded rubber is formed into a tape shape by roll processing, is charged from the hopper 9, is extruded by the screw arranged inside, and the wall thickness of the inner tube rubber 7 is adjusted by the die 11 arranged at the extrusion port. . Generally, the inner tube rubber 7 extruded on the outer periphery of the mandrel 1 is wound around the reel 13,
Then, one or a plurality of fiber reinforcing layers are formed on the outer circumference of the inner tube rubber 7 by a blade method or a spiral method, and the outer tube rubber is extruded on the fiber reinforcing layer for vulcanization molding.

[0004]

However, the inner tube rubber 7 extruded on the outer periphery of the mandrel 1 is not easily removed by the reel 13
Since the lower layer has a higher tightening force due to being wound up, the appearance is crushed to cause uneven thickness, which causes a problem that the shape at the time of extrusion cannot be maintained. Although such uneven thickness can be prevented to some extent by cooling the inner tube rubber after extrusion and then winding it up, it cannot be completely prevented and the productivity is reduced to that extent. In addition, since the inner tube rubbers 7 may stick to each other during winding, the inner tube rubbers 7 are wound while applying an adhesion preventive on the surface thereof. When the anti-adhesion agent is applied, there is a problem that the adhesive force between the inner tube rubber 7 and the wound reinforcing fiber is reduced.

When a low-priced compounded rubber is used for cost reduction like a radiator hose, a large amount of oil is contained in the compounded rubber. In this way, the compounded rubber containing a large amount of oil has a low viscosity,
Unvulcanized compounded rubber has low strength and heavy specific gravity. For this reason, roll processability is poor and it is difficult to take tape for extrusion molding, and when continuous molding is performed by braiding a reinforcing thread on the extruded inner tube rubber and further extruding the outer tube rubber. Had a large settling and could not be molded. As described above, the conventional unvulcanized rubber has a low viscosity, and it is difficult to maintain the molded shape before vulcanization.

The present invention has been made in view of the present situation, and an object thereof is to provide a compounded rubber having no cold flow and no appearance collapse.

[0007]

In order to achieve the above object, the compounded rubber according to the present invention is a semi-vulcanized compounded rubber obtained by heat-treating an unvulcanized compounded rubber obtained by kneading various compounding agents into a raw rubber. Alternatively, the semi-vulcanized compounded rubber is mixed with the unvulcanized compounded rubber having the same compounding content before the heat treatment.
In this specification, vulcanization means that a cross-linking reaction is caused between the molecules of the raw rubber by heat treatment to form an elastic body, and therefore, after the cross-linking reaction, processing such as extrusion molding and mold molding by thermosetting is performed. It becomes impossible. Further, semi-vulcanization means heat-treating unvulcanized compounded rubber to such an extent that a complete crosslinking reaction does not occur between molecules of the raw rubber. Therefore, semi-vulcanized compounded rubber is a compoundable rubber that can be processed and molded. is there.

Vulcanization generally involves compounding rubbers 110-170.
It is carried out while heating and pressurizing at ℃, but semi-vulcanization is carried out at 100 to 140 ℃ at which the compounded rubber does not undergo a complete crosslinking reaction, and in the present invention, it is carried out in the state of completely compounded rubber as a material before molding. . The unvulcanized compounded rubber is kneaded with a compounding agent such as a vulcanizing agent, a vulcanization aid, a vulcanization accelerator, an antiaging agent, a filler, a reinforcing agent, a plasticizer, and the type and proportion of the compounding agent. Is appropriately determined according to the application of the product. The semi-vulcanized compounded rubber can be used as it is as a material, of course, depending on the content of the unvulcanized compounded rubber, the semi-vulcanized compounded rubber and the unvulcanized compound of the same composition before being semi-vulcanized You may mix and use a compounding rubber. The ratio may be appropriately determined depending on the content of the compound, the molding method, the product shape, and the like.

[0009]

In the unvulcanized compounded rubber, the viscosity is increased by semi-vulcanization, so that plastic deformation is prevented and workability is improved. Further, plastic deformation can be prevented by kneading a semi-vulcanized compounded rubber having a high viscosity with an unvulcanized compounded rubber.

[0010]

EXAMPLES The present invention will be described below based on examples. First, in the first example, as a compound rubber for a hose, NBR15 containing CSM 85% as a raw material rubber and medium-high nitrile is used.
%, And this was kneaded at 120 ° C. for 5 minutes to obtain a semi-vulcanized compounded rubber. Example 1 was prepared by mixing 15 parts of the semi-vulcanized compounded rubber with 100 parts of the unvulcanized compounded rubber having the same composition, and Comparative Example 1 was an unvulcanized compounded rubber containing no semi-vulcanized compounded rubber. 15mm inside diameter and 22m outside diameter, respectively
Extrude a 50 m hose by 50 m and wind it on a reel.
The measurement by a 0 ° C. curast meter and the collapse of the hose inside the reel were observed. The comparison results are as shown in Table 1.

[0011]

[Table 1]

EPDM, which is the raw rubber, contains a large amount of oil (100 PHR) in a rubber compound rubber for a radiator hose at 140 ° C. for 5 minutes to obtain a semi-vulcanized compound rubber, and 30 parts of this semi-vulcanized compound rubber are the same. It was mixed in 100 parts of the unvulcanized compounded rubber. The semi-vulcanized compounded rubber mixture was used as Example 2 and the unvulcanized compounded rubber before mixing was used as Comparative Example 2. The roll processability of both and the crushing of the radiator hose during continuous molding were compared. The radiator hose had an inner tube rubber having an inner diameter of 34 mm and an outer diameter of 36 mm, a rayon yarn was used as a reinforcing thread, and the outer tube rubber had a wall thickness of 1 mm. The comparison results are shown in Table 2.

[0013]

[Table 2]

The same compounded rubber as in Example 2 above was used at 130 ° C.
It was heat treated for 5 minutes to obtain a semi-vulcanized compound rubber, which was used in Example 3.
And The conditions of this Example 3 were the same as those of Example 2 except that 100% of semi-vulcanized rubber was used. The comparison results are shown in Table 3.

[Table 3]

Next, the appearance of the EPDM microcellular rubber was observed. That is, EP which is a raw material rubber
30 parts of semi-vulcanized compounded rubber obtained by heat-treating DM mixed with compounding agent at 130 ° C. for 5 minutes was used for unvulcanized compounded rubber 10
It was mixed in 0 part and further subjected to UHF vulcanization, which was designated as Example 4. The unvulcanized compounded rubber containing no semi-vulcanized compounded rubber was designated as Comparative Example 3. In Example 4, a microcellular rubber having a small heat shrinkage after vulcanization and a fine texture was obtained. The comparison results are shown in Table 4.

[0016]

[Table 4]

[0017]

As is clear from the above examples, the semi-vulcanized compounded rubber or the unvulcanized compounded rubber containing the semi-vulcanized compounded rubber has no cold flow, prevents appearance crushing and is excellent in processability. ing.

[Brief description of drawings]

FIG. 1 is a side view illustrating a conventional extrusion process of an inner tube rubber.

[Explanation of symbols] 1 mandrel 3 reel 4 extruder 7 inner tube rubber 11 die 13 reel

Claims (3)

[Claims] 1. A compounded rubber with improved processability, characterized by heat-treating an unvulcanized compounded rubber obtained by kneading various compounding agents into a raw rubber to obtain a semi-vulcanized compounded rubber. 2. A processability characterized by mixing a semi-vulcanized compounded rubber obtained by heat-treating an unvulcanized compounded rubber obtained by kneading various compounding agents with a raw material rubber into an unvulcanized compounded rubber having the same compounding content. Improved compounded rubber. 3. A compounded rubber with improved processability according to claim 1 or 2, wherein the compounded rubber is heat-treated in the range of 100 ° C. to 140 ° C. to obtain a semi-vulcanized compounded rubber.