JP2594233B2 - Manufacturing method of breathable insoles - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

OBJECT OF THE INVENTION The present invention relates to a method for producing a breathable shoe insole which fits a wearer's foot without three-dimensionally forming the sole of the foot in advance.

[0002] Shoe insoles are foamed products such as plastics and rubber, but if a product that fits the shape of the wearer's foot is to be obtained, the shape of the insole is conformed to the contour of the sole using a closed mold. It must be formed in advance. This molding operation has to be carried out individually and is costly.

[0003] A soft vulcanized latex sponge sheet, which can be produced without using a closed mold, can be simply trimmed and used as a shoe insole. This method is efficient and cost effective because it only trims the continuous sponge sheet by cutting. Even a product made by cutting out a flat sponge sheet of uniform thickness in this way is greatly compressed in the swelled parts of the heel and toes, and the degree of compression is small in the depressed parts such as the toes, so when wearing it Deforms to fit the shape of the foot. However, the rubber sponge has a repulsive force, and therefore tends to return to its original non-compressed state. Also, due to its relatively strong repulsion, the toe grip is weak, making it unsuitable for sports shoe insoles.

DISCLOSURE OF THE INVENTION The present invention enjoys the efficiency and economics of a shoe insole made by hollowing out a flat vulcanized latex sponge sheet that can be produced without the use of a closed mold as described above. The present invention provides a method for producing a breathable insole with no feeling of oppression and excellent grip.

[0005] The method of the present invention is to form a sponge sheet having a uniform thickness from the compounded latex and cut out the sponge sheet to form a shoe insole as in the ordinary method. Is added.

The added tacky acrylic resin acts like a pressure-sensitive adhesive, temporarily adhering the sponge cell walls crushed by body pressure and preventing them from returning to their original shape. However, after a certain period of time after the pressure is released, the repulsion of the rubber overcomes the adhesive force, and the sponge returns to the non-compressed state. In other words, it has a shape following function for temporarily storing the shape of the sole. Therefore, there is no feeling of oppression even when worn for a long time, and the grip force of the toe increases.

[0007] In the preferred embodiment , the "formulated latex" refers to a natural and / or synthetic rubber latex containing a vulcanizing agent (sulfur), a vulcanization accelerator, an accelerator, an antioxidant, a filler and the like. .

[0008] Adhesive acrylic emulsions have been used as adhesives for pressure sensitive and / or removable adhesive tapes and labels, and are themselves commercially available as office adhesives. Usually, it is produced by copolymerizing a long-chain alkyl ester of acrylic acid such as n-butyl, 2-ethylhexyl, lauryl, acrylic acid, and another monomer by an emulsion polymerization method. Such tacky acrylic resin emulsions are known per se, and there are many commercially available products, so that no further detailed description is required.

The ratio of the tacky acrylic resin emulsion to be added to the compounded latex is such that the crushed sponge cell is kept in a crushed state for a while after the pressure is released, but after a certain period of time, for example, several minutes to several hours after the pressure is released. Must be allowed to return to the uncompressed state. In general, it is 1 to 20 parts, especially 2 to 10 parts, as solids per 100 parts of the prepared latex.

For this purpose, a predetermined amount of an adhesive acrylic resin emulsion is added to the compounded latex, a foaming agent is added,
The foam is mechanically foamed to form a foam, and a gelling agent such as ammonium chloride is further added.

The substrate may be released using a release paper or a release belt, but may be peeled off later. However, by forming a latex foam layer directly on a nonwoven fabric, a woven fabric, a knitted fabric, or the like, the base material is integrated with the base fabric. Insoles can be manufactured.

Next, the latex foam layer thus formed is heated in a hot air drier at 80 to 90 ° C. for about 10 to 20 hours.
Heat for minutes and dry simultaneously with gelation. Next, this is heated at a temperature and time suitable for vulcanization to form a vulcanized latex sponge sheet, and an insole is formed by cutting.

Example A compounded latex was prepared according to the following formulation. NR latex 700 parts by weight Synthetic latex 300 parts by weight Foaming agent 50 parts by weight Vulcanization accelerator 3 parts by weight Sulfur 2 parts by weight Zinc white 5 parts by weight Antioxidant 2 parts by weight Adhesive acrylic resin emulsion 50 parts by weight (as solid content) )

[0014] The required amount of the prepared latex is weighed, and
After foaming to twice the volume and mixing an appropriate amount of ammonium chloride as a gelling agent, it is cast on a non-woven fabric to a required thickness and heated in a hot air dryer at a temperature of 80 to 90 ° C. for about 10 to 20 minutes. Gelled and dried. Further, this sheet was heated and vulcanized at 120 ° C. for 10 minutes in a hot air drier to obtain a vulcanized sponge sheet. This sheet was cut into a shoe insole shape by cutting. The resulting product maintained breathability, was excellent in fit and grip, and did not have a feeling of oppression even when worn for a long time.

The acrylic resin emulsion used was "Ultrasol W-20" manufactured by Ganz Kasei Co., Ltd.
Acrylic ester copolymer resin emulsion having a solid content of about 55%, a pH of about 7.0, and a viscosity of about 1000 mPa · S sold under the name of “0”.

Claims (3)

(57) [Claims] (1) A foam of a compounded rubber latex containing an adhesive acrylic resin emulsion is cast into a flat sheet, gelled and vulcanized, and the obtained flat vulcanized latex sponge sheet is formed into a predetermined shape. A method for producing a breathable insole, comprising cutting. 2. The method according to claim 1, wherein the vulcanized latex sponge sheet is formed on a base cloth. 3. The method according to claim 1, wherein the adhesive acrylic resin emulsion is added in an amount of 1 to 20 parts per 100 parts of rubber latex as a solid content.