JP2884327B2 - Manufacturing method of foamed rubber molded body - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a foamed rubber molded article used for shoe soles or the lower surface of furniture furniture, art, precision machines, precision measuring machines, and the like.

[0002]

2. Description of the Related Art A foamed rubber molded product is most generally obtained by filling a press mold cavity with a so-called foamable unvulcanized rubber mixture containing a foaming agent and a foaming aid, and then heating and pressurizing the mixture. Was manufactured by According to such a manufacturing method, vulcanization of rubber and generation of gas due to decomposition of a foaming agent occur simultaneously in the mold cavity, and at the end of the vulcanization, the vulcanized rubber is in a state of containing gas. When the hermetically closed state of the cavity was released, the cavity expanded significantly at that moment or after a lapse of time.

[0003] When such a swelling has a three-dimensional design on the ground contact surface, such as a shoe sole, the three-dimensional design itself expands, loses sharpness, and the size of the sole changes. In addition, the size, which once seems to be constant, also has a risk that the gas partially contained in the vulcanized rubber may escape over time and conversely shrink. In an attempt to remedy such a drawback, an amount is set in a press mold cavity as disclosed in JP-A-49-125153 such that the volume in the cavity coincides with the volume when foamed and vulcanized in an open state. Add foamable unvulcanized rubber mixture, heat,
A method of applying pressure and foam vulcanization was disclosed.

[0004]

Problems to be Solved by the Invention
According to the method for producing a foamed rubber molded article as shown in JP-A No. 53,
Although the above-mentioned disadvantages that existed before that had been considerably improved, it is still necessary to sharpen a three-dimensional design such as a shoe sole and accurately determine the size in any case. In the case of a product, a satisfactory result was not obtained. An object of the present invention is to provide a method capable of obtaining a foamed rubber molded article having no such a defect by using a press mold.

[0005]

According to the present invention, there is provided a foamable unvulcanized material having a volume in a press mold cavity which is at least equal to the volume of the cavity when foamed and vulcanized in an open state. When the rubber mixture is charged , heated, pressurized, foamed, and vulcanized, glass foam , carbon fiber, metal fiber, and whisker are added to the foamable unvulcanized rubber mixture.
Hard fiber of any one of fiber and synthetic fiber, or two or more
Lowering the flowability of the above mixture of hard fibers during molding
This is a method for producing a foamed rubber molded article characterized in that the amount not to be mixed is previously mixed.

In practicing the present invention, glass fibers, carbon fibers, metal fibers, whisker fibers, synthetic fibers and the like are used as hard fibers, and among them, glass fibers and aromatic polyamide fibers are often used. The former is 20 to 60 parts by weight with respect to 100 parts by weight of rubber, and the latter is 1 to 100 parts by weight.
When the amount is less than this range, the molded body expands immediately after vulcanization, and when the amount exceeds this range, the amount of the decomposition gas of the foaming agent passing through the fiber to the outside increases sharply and shrinks. It is inappropriate.

[0007] The difference between the former and the latter is that the fiber length is mixed and then measured in a state of being dispersed in rubber.
The former was about 350 microns before mixing,
.About.350 microns, the latter being 15 denier and 2-10 mm, due to the fact that its length did not change. This indicates that the former is shortened by the shear force during mixing, while the latter does not change much. These fibers reduce the fluidity of the admixture when the number of blending parts is increased, but the fluidity can be prevented from decreasing by partially using glass fibers or carbon fibers.

[0008] The foamed rubber molded article of the present invention thus obtained can be used for shoe soles, furniture furniture, art objects, precision machines,
It is used for the lower surface of a precision measuring instrument or the like, and is particularly suitable for shoe soles and the like that require a three-dimensional decorative design on the surface and that must accurately come out in size and the like.

[0009]

According to the present invention, the unvulcanized rubber mixture used for producing a foamed rubber molded product contains glass fibers, fibers, and the like.
Carbon fiber, metal fiber, whisker fiber, synthetic fiber
One hard fiber or a mixture of two or more hard fibers
The amount of the material that does not lower the fluidity during molding
Because it is mixed, in the press mold cavity,
An unvulcanized rubber admixture in an amount such that the volume in the cavity is equal to the volume when foamed and vulcanized in the open state, or more, is heated and pressurized to foam and vulcanize. The amount that completely matches the volume when pressurized in the press mold cavity, that is, the amount that completely fills the press mold cavity is not filled, and the unvulcanized rubber admixture has a very large reinforcing property to rubber. In combination with the incorporation of the hard fibers, it is possible to confine the force of increasing the volume of the cavity or more, and to exhibit a sharp three-dimensional design and an accurate size.

[0010]

【Example】

[Table 1]

In Table 1, the aromatic polyamide fibers are:
It passes through a screen with a mesh spacing of 10 mm at 15 denier,
In addition, a glass fiber having a length of 2 to 10 mm and a glass fiber having a diameter of 10 μm and a length of 3 mm was used to obtain eight kinds of foamable unvulcanized rubber admixtures. 128cc inside cavity
Using a press mold having a mold size (160 × 160 × 5) mm, put 78 g of the foamable unvulcanized rubber mixture into the cavity, cover the plate with a plate, and seal the mixture.
Foam vulcanization was performed under the conditions of 0 ° C. × 7 minutes. Thereafter, the mold was taken out of the mold cavity and opened, and various physical properties were measured. The results are shown in Table 2.

[0012]

[Table 2]

[0013] In Table 2, the free expansion ratio means that a rolled rubber specimen is punched into a diameter of 3 cm and heated at 140 ° C.
It is the ratio between the thickness when expanded (when cooled) and the thickness immediately after rolling, and the higher the magnification, the better the expansion, and the hardness indicates the value measured with a sponge hardness tester. As shown in Table 2, the present invention was able to achieve its object in all Examples, but among them, No. 8 in which both the aromatic polyamide fiber and the glass fiber were used in combination was good.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code FI B29K 105: 04 105: 12 105: 24 B29L 31:50

Claims (4)

(57) [Claims] 1. A foamable unvulcanized rubber admixture in an amount equal to or greater than the volume of the cavity in the press mold cavity and the volume when foamed and vulcanized in the open state is matched in the press mold cavity. When pressurizing, foaming, and vulcanizing, the foamable unvulcanized rubber admixture is mixed with glass fiber or carbon fiber.
Any one of fiber, metal fiber, whisker fiber and synthetic fiber
One hard fiber or a mixture of two or more hard fibers
A method for producing a foamed rubber molded article, characterized in that an amount that does not decrease fluidity during shaping is previously mixed. 2. The foamable unvulcanized rubber admixture is rubber 1
20 to 60 parts by weight of glass fiber mixed with 00 parts by weight
Preparation of foam rubber molded article according to claim 1, wherein the the. 3. The foamable unvulcanized rubber admixture is rubber 1
Aromatic polymer having a length of 2 to 10 mm based on 00 parts by weight
The method for producing a foamed rubber molded article according to claim 1 , wherein 20 to 40 parts by weight of a mid fiber is mixed . 4. The method according to claim 1, wherein the foamable unvulcanized rubber admixture is
A mixture of lath fiber and aromatic polyamide fiber is mixed with rubber.
2. The method for producing a foamed rubber molded article according to claim 1, wherein the foamed rubber molded article is added.