JPS6124925B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method of manufacturing injection molded shoes, and in particular, integrates a heel reinforcing moon shape into a desired shape during injection molding of a contact sole, and firmly attaches it to a predetermined location on the inner surface of the heel. This invention relates to a method for manufacturing wet injection molded shoes.

The moon-shaped heel reinforcement allows the heel of the wearer's foot to fit comfortably into a predetermined location on the inner surface of the heel of the shoe, creating a stable condition and allowing the wearer to walk comfortably and quickly with good balance. It is used to keep the heel area in a beautiful shape.

Conventionally, various methods have been proposed for attaching a heel reinforcing moon shape to the inner surface of the heel of injection molded shoes.

For example, in the above-mentioned injection molding method, which can mold a ground-contact sole onto the lower surface of a shoe in a short period of time, such as a few minutes, a method using a heel reinforcing moon mold made of fabric and thermoplastic resin has been proposed. .

However, in the previously proposed method, thermoplastic resin such as styrene-butadiene block copolymer or polyurethane elastomer, which softens and becomes sticky at relatively high temperatures of 120 to 200°C, is used in the heel reinforcement moon shape. I was using it.

In the injection molding of shoes, it is of course impossible to heat the last to such high temperatures due to the cooling cycle and the hanging operation of the shoe cover, so the molding temperature is between 120 and 200℃.
In order to soften and make the heel reinforcing moon shape sticky, the heel part of the heel suspended in the last must be heated from the outside with hot air or a heating iron, and a device for this purpose is required. However, it also had the disadvantage of increasing the number of steps.

The purpose of the present invention is to eliminate all the drawbacks of the conventional methods as described above.
This was achieved by combining a thermoplastic resin that becomes sticky at 90°C and a thermoplastic resin that softens at 60 to 90°C.

More specifically, the moon shape for heel reinforcement used in the present invention is made of cloth, a thin thermoplastic resin layer that becomes sticky at 60 to 90°C, a thermoplastic resin layer that softens at 60 to 90°C,
A thin layer of thermoplastic resin that becomes sticky at 60 to 90°C is laminated in sequence, and the outer thin layer of thermoplastic resin, which becomes sticky at 60 to 90°C, is applied to the heel of the inner surface of the sleeve and sewn. Hereafter, the object of the present invention is achieved by carrying out injection molding for forming the ground sole.

In the present invention, the shoe last is heated to 60 to 90°C by an inserted heater or the like, and during shoe manufacturing, a shoe cover having a moon shape for heel reinforcement is suspended on the heel part of the inner surface of the shoe cover. When inserted, the entire heel reinforcing moon shape that is in direct contact with the shoe last is immediately heated to 60 to 90 degrees Celsius.
The thermoplastic resin layer, which softens at ℃, easily conforms to the heel shape of the last, and the thin thermoplastic resin layer, which becomes sticky at 60 to 90℃, allows the thermoplastic resin layer to be applied in its original shape to the heel of the shoe last. After the injection of the ground sole material into the cavity is completed,
The moon shape for heel reinforcement provides strong adhesion and fixes the thermoplastic resin layer in a desired shape.

On the other hand, it is usually considered to keep the shoe last as low as possible due to the cycle-up of injection molding, but if the lower mold is sufficiently cooled, the temperature of the shoe last can be lowered.
Even if the temperature is 60 to 90°C, there is no noticeable increase in the forming cycle, and there is no particular problem in the operation of hanging the shoe last.

In particular, in the present invention, it goes without saying that the worker will not get burned, and the heel cover will not be damaged or discolored, but the moon shape for reinforcing the heel is adhered to the inner surface of the heel cover. In addition, no special heating equipment or process is required to form the desired shape, and excellent effects can be achieved, such as the equipment cost being simplified and the manufacturing cost being reduced at the same time.

In carrying out the present invention, polymethylene terephthalate having a hydroxyl group or a carboxyl group at the molecular end is used as the thermoplastic resin that becomes sticky at 60 to 80°C. Among these resins, those having a molecular weight of 18,000 to 25,000, a melt viscosity of 1,000 to 2,000 poise at 200°C, and a melting point of 110 to 125°C are particularly suitable. As the thermoplastic resin that softens at 60 to 80°C, an ethylene-vinyl acetate copolymer having a vinyl acetate content of 10 to 12% by weight is used.

Example As shown in Fig. 1, one side of a fabric 1 cut into a moon shape for heel reinforcement was prepared with hydroxyl groups and carboxyl groups at the ends dissolved in a mixed solvent of toluene and methyl ethyl ketone at a ratio of 80/20. Polymethylene terephthalate (molecular weight approximately 20,000, melt viscosity at 200°C 1800 poise, mp 110°C) solution was laminated to form two 150 micron thin layers, and 1.2 mm of vinyl acetate content 12% was applied to the two sides of the thin layer. An ethylene-vinyl fraud acid copolymer layer 3 of
They are laminated to form a micron thin layer 4 to obtain a moon shape 5 for heel reinforcement.

As shown in FIG. 2, the heel reinforcement moon shape 5 is
The four thin layers are applied to the inner heel part and sewn together with the sole cloth 15 (7), and the shoe cover (6) is hung into a shoe last (8) heated to approximately 70°C by an inserted heater (not shown). .

As shown in FIG. 3, this shoe last 8 is combined with a grounded sole mold 11 consisting of a side mold 9 and a bottom mold 10, and molten polyvinyl chloride 12 at 180°C is injected into the cavity 14 through the injection hole. Injecting and filling, the fabric 1 and the ethylene-vinyl acetate copolymer layer 3 are completely adhered by the heat-adhesive thin layer 2 of the last 8,
This adhesive is adhered to the inner surface of the shoe cover 6 using the same adhesive thin layer 4, and at the same time, the softened ethylene-vinyl acetate copolymer layer 3 is mixed so that it has the same shape as the heel part of the shoe last 8. An injection molded shoe having a reinforcing moon shape of a desired shape was obtained.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view of a moon shape for heel reinforcement used in the present invention, and FIGS. 2 and 3 are cross-sectional views showing the method for manufacturing injection molded shoes of the present invention. 1... Fabric, 2, 4... Polymethylene terephthalate thin layer having a hydroxyl group and a carboxyl group at the end, 3... Ethylene-vinyl acetate copolymer layer, 5... Moon shape for heel reinforcement, 6... Yoshihiro, 7...
... Sewing, 8 ... Shoe last, 9 ... Side mold, 10 ... Lower mold, 11 ... Ground sole mold, 12 ... Polyvinyl chloride, 13 ... Injection hole, 14 ... Hollow part, 15...
...Bottom cloth.

Claims (1)

[Claims] 1 Fabric, a thin layer of polymethylene terephthalate having hydroxyl groups and carboxyl groups at the ends,
A moon-shaped heel reinforcement in which an ethylene-vinyl acetate copolymer layer with a vinyl acetate content of 10 to 12% by weight and a thin layer of polymethylene terephthalate having hydroxyl groups and carboxyl groups at the ends are laminated in sequence.
A thin layer of polymethylene terephthalate having hydroxyl and carboxyl groups at the outer end is sewn onto the heel part of the inner surface of the heel, and the heel is heated at 60 to 90°C.
The shoe is hung on the last of the shoe, combined with the grounding sole molding part, the resin for the grounding sole is injected into the cavity formed at that time, the grounding sole is molded on the lower surface of the shoe, and the entire moon shape for heel reinforcement is integrated. A method for manufacturing injection molded shoes, which is characterized by molding them into a desired shape and simultaneously adhering them to the inner surface of the shoe.