JPH0513648B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Field of Application) The present invention relates to an injection molding method for shoe soles.

(Prior art) Conventionally, as disclosed in Japanese Patent Application Laid-open No. 55-158001, a core material made of vinyl chloride resin, polyethylene resin, polyurethane resin, etc. is adhered to the bottom of a sash suspended at the last, and the bottom surface of the A sole molding material made of vinyl chloride, thermoplastic rubber, etc. is injected into the sole molding cavity formed in the mold to form the sole, and the sole is laminated on the upper surface of the sole. A method for achieving the shape-retaining effect has been proposed.

However, if vinyl chloride, polyethylene, polystyrene, ABS resin, etc. are used as the core material,
The heating during sole injection molding softens the core material and causes it to sag into the mold cavity, impairing the fluidity of the sole molding material, causing air bubbles to enter the molded sole and causing internal damage. The disadvantages are that cavities are formed in the sole, the surface is depressed, the physical properties and appearance of the sole are deteriorated, and the shape-retaining effect of the core material is significantly reduced.

(Problems to be Solved by the Invention) The present invention aims to eliminate these drawbacks and provide a lightweight shoe sole with good appearance, shape retention effect, physical properties, landing stability, and cushioning properties. It is.

(Means for Solving the Problems) As explained below with reference to the drawings, the present invention provides an outsole 2 having elastic support protrusions 21, 21... on the upper surface and a notch 22 in the center of the mold. After supporting the sole reinforcing piece 3 made of thermoplastic resin, which is temporarily fixed to the bottom surface of the last 5 by the repulsive elasticity of the elastic support protrusions 21, 21..., on the bottom surface of the last 5, the mold cavity is The gist of the invention is an injection molding method for a shoe sole, which is characterized in that the midsole 4 and the cushion part 41 are foam-molded by injecting and filling a foamable midsole molding material into the cutout 22 of the outsole. It is something to do.

In this invention, the outsole 2 is made of rubber, thermoplastic elastomer, vinyl chloride, polyurethane, etc., and is molded by compression molding, injection molding, etc., and the upper surface thereof has projections of an appropriate shape such as columnar, cylindrical, etc. 21, 21... is outsole 2
A notch 22 of an appropriate shape is provided at the center of the cutout 22 . In molding the outsole 2, a mold 1 in which the outsole 2 is set when molding the midsole, and a dummy last 6 facing the mold 1 having protrusion molding recesses 61, 61, . If the dummy last 6 is replaced with the last 5 to form the midsole 4 after the outsole 2 is compressed or injection molded, the outsole 2 can be molded into the mold 1 at the same time as the outsole 2 is molded.
This is convenient because it can be set to

In this invention, the sole reinforcing piece 3 is made of a hard thermoplastic resin such as hard vinyl chloride, polyethylene, polypropylene, polystyrene, or acrylonitrile-butadiene-styrene copolymer. Anchor holes 31, 31, . . . may be provided to facilitate the flow of material into the outsole notch 22.

In this invention, the sole reinforcing piece 3 includes a last 5
The holding needles 51, 51 protruding from the bottom surface of the outsole are positioned and temporarily held on the bottom surface of the last 5 by means of fitting grooves or adhesive, and the last 5 is set in the mold 1. The mold 1 with the outsole 2 set thereon is lowered relative to the last 5, or the mold 1 with the outsole 2 set is raised relative to the last 5, and the protrusions 21, 21... formed on the upper surface of the outsole 2 are temporarily fixed and held on the bottom surface of the last 5. Sole reinforcement piece 3
The sole reinforcing piece 3 is supported on the bottom surface of the last 5 by the repulsive elasticity of the protrusions 21, 21.... Then, a thermoplastic resin such as thermoplastic rubber such as vinyl chloride, 1.2 polybutadiene, or styrene-butadiene block copolymer is injected into the mold cavity 11 and the notch 22 of the outsole in a heated molten state by a conventional method. Then, the midsole 4 and cushion portion 41 are molded.

Note that 1' in the drawings indicates a side mold.

(Effects of the Invention) As described above, in this invention, the sole reinforcing piece 3 is attached to the bottom surface of the last 5 by the rebound elasticity of the elastic support protrusions 21, 21... formed on the upper surface of the outsole 2 during midsole injection molding. Because it is supported by
Even if the sole reinforcing piece 3 is softened by the heating during mid-sole injection molding, the mold cavity 1
1, and unlike conventional methods, the fluidity of the midsole molding material is inhibited during midsole injection molding, and air bubbles are not mixed into the midsole 4 or the sole reinforcing piece 3 is deformed. It is possible to provide a shoe sole that has a good appearance, excellent physical properties, and has a good shape-retaining effect due to the sole reinforcing piece 3.
Further, in the obtained shoe sole, the sole reinforcing piece 3 has a protrusion 21,
Since it is directly supported by the outsole 2 through 21..., even when the midsole 4 is made of a soft material, it has good support for the sole of the foot and has excellent landing stability. I can do it.

Furthermore, the midsole molding material is injected and filled into the notch 22 of the outsole, and the cushion part 41 is exposed and foam-molded on the contact surface of the outsole, so that a light sole with good cushioning properties can be provided.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view of a main part showing a molded state of a shoe sole according to the present invention, and FIG. 2 is a cross-sectional view of a main part showing a molded state of an outsole used in this invention. Explanation of code, 1, 1'...Mold, 11...
...Mold cavity, 2...Outsole, 2
1...Protrusion, 3...Sole reinforcement piece, 4...Mitsudosole, 41...Cushion part, 5...Last, 5
1... Holding needle, 6... Dummy last, 61... Concave portion, 62... Convex portion.

Claims (1)

[Claims] 1. Set the outsole 2, which has elastic support protrusions 21, 21... on the upper surface and a notch 22 in the center, on the bottom of the mold, and the outsole 2 is attached to the bottom surface of the last 5 by the repulsive elasticity of the elastic support protrusions 21, 21... After supporting the temporary sole reinforcing piece 3 made of thermoplastic resin on the bottom surface of the last 5, foamable midsole molding material is injected and filled into the mold cavity 11 and the notch 22 of the outsole. The injection molding method for the sole of a shoe is characterized in that the midsole 4 and the cushion part 41 are foam-molded.