JPS6357041B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method of manufacturing shoes having a foamed polyurethane outer sole, and more particularly to a method of manufacturing shoes having a foamed polyurethane outer sole by a unit sole method in which a rubber tape is attached to the lower peripheral edge.

Foamed polyurethane outer soles are widely used because the manufacturing process is relatively simple, they are lightweight, highly elastic, have excellent bending resistance in cold weather, and are comfortable to wear.

Methods for manufacturing shoes using foamed polyurethane outsole having such characteristics include a direct sole method and a unit sole method.
The direct sawing method is a simple process and is widely used, but it creates a gap between the lower periphery of the shoelace suspended in the last and the upper edge of the outer sole forming cavity of the lower mold.
There is a risk that the foamed polyurethane raw material liquid may spill out and stain the cover, and since the lower peripheral tape and the outer sole are both made of the same foamed polyurethane, the appearance tends to be monotonous.
Although the process of the unit sole method is relatively complicated, since the foamed polyurethane outer sole is attached to the lower surface of the shoe after the protrusion has been removed, the lower periphery of the shoe is not soiled, and the present applicant's If the previous application (Japanese Patent Laid-Open No. 60-153802) is carried out, it is possible to apply a foamed polyurethane sole to the lower surface of the shoe cover with an adhesive, and apply unvulcanized adhesive to the contact area between the contacted shoe cover and the foamed polyurethane sole. If the rubber tape is brought into contact with an adhesive and then hot air vulcanization is performed using pressurized air to vulcanize the adhesives and the unvulcanized rubber tape, the appearance of so-called hand-applied shoes can be created. This eliminates the drawback of a monotonous appearance.

In general, foamed polyurethane outsole comes in two types: heeled outsole, flat outsole, etc. Of course, not only heeled outsole but also flat outsole are used to make it easier to insert the foot when wearing the shoes. Also, in order to stabilize the center of gravity of the wearer's feet and reduce fatigue when walking, shoes with thicker heel parts are used.

However, when the thickness of the heel becomes 8 to 10 mm or more, in the case of the unit sole method,
The molded foamed polyurethane outer sole is brought into contact with the lower surface of the shoe cover using an adhesive, the unvulcanized rubber tape is brought into contact with the adhesive at the desired location, and each adhesive and the unvulcanized rubber tape are vulcanized using heated and pressurized air. Sometimes, because the heel part contains a lot of air bubbles, the heel part becomes more concave than the other parts, that is, the thinner part, and the appearance of the shoe is spoiled.

The present invention addresses the above-mentioned drawbacks, namely, when manufacturing shoes with a foamed polyurethane outsole made by the unit soling method in which a rubber tape is attached to the lower peripheral edge, even if the outsole has a thick heel part, the heel The purpose is to manufacture shoes that do not dent the ground contact surface of the lower mold, and the heel part has a deeper outer sole forming cavity than the toe part, and a liquid foamed polyurethane raw material is injected into the cavity part of the lower mold. Then, it is combined with an upper mold having a convex part on the lower heel part and a convex part smaller than the convex part on the lower surface slightly in front of the heel part, and is foamed and hardened at an appropriate temperature, so that the heel part is thicker than the toe part. A foamed polyurethane outer sole is molded with a concave portion on the upper surface of the heel portion and a concave portion smaller than the concave portion on the upper surface slightly forward of the heel portion, and appropriate filling is inserted into the concave portion on the upper surface of the heel portion. Apply adhesive to the lower surface, apply unvulcanized rubber tape to the desired location using adhesive, and use heated and pressurized air to vulcanize each adhesive and unvulcanized rubber tape to manufacture shoes with foamed polyurethane outer soles. This was achieved through this.

The above means for achieving the object of the present invention was achieved based on the following reasoning.

The reason why the heel part is more conspicuously depressed than the toe part of the foamed polyurethane outsole during vulcanization with heated and pressurized air is because the heel part is thicker and therefore contains more air bubbles. Therefore, the first thought is that if a recess is provided on the upper surface of the thick heel, that is, the surface that adheres to the lower surface of the heel, and the amount of air bubbles is made to be the same as that of the toe, the recess may be eliminated.

However, since the foamed polyurethane outer bottom of this concave portion is adhered to the lower surface of the sleeve and is almost sealed, the air in the concave portion is heated during the initial stage of vulcanization using heated and pressurized air. It expands rapidly and the pressure increases, causing the outsole to protrude toward the contact surface of the heel. However, when the vulcanization with heated and pressurized air is finished and the air inside the recess cools down, its volume decreases, and the pressure decreases, the side of the heel that touches the ground becomes suctioned, causing it to dent.

Therefore, the object of the present invention cannot be achieved simply by providing a concave portion on the upper surface of the heel portion of a foamed polyurethane outer sole. If the material is filled almost completely, or inserted so that there are appropriate gaps around it, or if a honeycomb-shaped molded body is inserted, these will act as a support and will be heated and heated. After vulcanization with compressed air, there are almost no large dents on the heel contact surface. In this case, the filling does not necessarily need to be attached with an adhesive or the like, and if a material with a specific gravity smaller than the foamed polyurethane outer sole is used, it will also help reduce the weight of the shoe.

However, by using only the above means, the object of the present invention has not yet been completely achieved, and the physical properties of the foamed polyurethane forming the outer sole and the filling are different, and there is a step between the upper surfaces of the two. When this happens, there was a phenomenon in which the contact surface side of the front portion of the concave portion was depressed slightly in front of the concave portion. Therefore, as in the present invention, if a concave portion smaller than the concave portion is provided on the upper surface slightly forward of the concave portion on the upper surface of the heel, the above-mentioned phenomenon will not occur at all, and the object of the present invention will be completely achieved. be. At this time, it goes without saying that a filler of an appropriate shape must be inserted into the recess on the upper surface of the heel.

Examples of the present invention using the above means will be described below.

Example As shown in FIG. 1, a lower mold 4 having an outer sole forming cavity 3 with a heel 2 deeper than a toe 1 and an upper mold 7 having a protrusion 6 on a lower surface 5 and a heel are prepared.

Next, as shown in FIG. 2, butylene adipate polyester,
Liquid substance 8 containing 1,4-butanediol and methylene diisocyanate as main components was injected, and 40
℃ upper mold 7, foamed and hardened for 5 minutes, and cut out of the mold to form a foamed polyurethane outer sole 10 with a specific gravity of 0.6, which is thicker at the heel than at the toe and has a concave portion 9 on the upper surface of the heel, as shown in FIG. A natural rubber foam 11 with a specific gravity of 0.3 is placed in the recess 9 as shown in FIG.
inserted.

As shown in FIG. 5, this foamed polyurethane outer sole 10 is brought into contact with the lower surface of the shoe cover (including the inner sole and inner core) 13 suspended from the shoe last 12 with an adhesive, and is attached to the lower peripheral edge of the side surface. The vulcanized rubber tape 14 was brought into contact with adhesive and placed in an indirect vulcanizer at a temperature of 110°C and an air pressure of 1.5 kg/cm ² for 65 minutes (including rise time) to vulcanize the adhesive and unvulcanized rubber tape. Shoes having the appearance of hand-pasted shoes were obtained. When this shoe was cut out from the shoe last 12 and observed one day and 30 days later, it was found that a slight dent had formed on the heel contact surface of the foamed polyurethane outsole 10.

After confirming the above phenomenon, an upper mold 7' having a protrusion 6' slightly smaller than the protrusion 6 on the lower surface 5 slightly in front of the protrusion 6 on the lower surface 5 as shown in FIG. A lower mold 4 as shown in FIG. A polyurethane outer sole 10' is molded, and a hard polyamide resin foam 1 with a specific gravity of 0.15 is placed in the concave portion 9.
1' was inserted.

Shoes were obtained in exactly the same manner as described in FIG. 5 below. This shoe had no dents at all on the heel contact surface, and did not impair the commercial value of the shoe, which was the intended purpose.

[Brief explanation of the drawing]

Fig. 1 is a cross-sectional view of the conventionally used upper and lower molds, Fig. 2 is a cross-sectional view showing a method for manufacturing a foamed polyurethane outer sole using the above-mentioned upper and lower molds, and Fig. 3 is a cross-sectional view of the above-mentioned upper and lower molds. FIG. 4 is a plan view of the foamed polyurethane outer sole molded with a mold, FIG. 4 is a sectional view showing a state in which the filling is inserted into the concave portion on the upper surface of the heel of the foamed polyurethane outer sole of FIG. 3, and FIG. FIG. 4 is a cross-sectional view of essential parts showing a method of manufacturing shoes using a foamed polyurethane outer sole, FIG. 6 is a cross-sectional view of an upper mold used in the present invention, and FIG. 7 is a cross-sectional view of the upper mold and first FIG. 8 is a plan view of a foamed polyurethane outsole molded using the lower mold shown in FIG. 8, and a cross-sectional view showing a state in which a filler is inserted into the concave portion on the upper surface of the heel portion of the foamed polyurethane outsole of FIG. 7. 1... Toe part, 2... Heel part, 3... Outer bottom forming hollow part, 4... Lower mold, 5... Lower surface, 6... Convex part,
7, 7'...Upper mold, 8...Liquid foamed polyurethane raw material, 9,9'...Concave portion, 10,10'...Foamed polyurethane outer bottom, 11,11'...Filling, 1
2... shoe last, 13... shoe cover, 14... unvulcanized rubber tape.

Claims (1)

[Claims] 1 Inject a foamed polyurethane raw material liquid into the outer sole forming cavity of the lower mold, which has a deeper heel than the toe, and form a convex part on the lower heel and on the lower surface slightly in front of the heel. Combine this with an upper mold each having a convex part smaller than the convex part, and foam and harden it at an appropriate temperature to form a concave part on the upper surface of the heel part, which is thicker than the toe part, and the concave part on the upper surface slightly in front of the heel part. A foamed polyurethane outer sole having recesses each smaller than the heel part is molded, appropriate filling is inserted into the recesses on the upper surface of the heel, it is brought into contact with the lower surface of the heel with adhesive, and unvulcanized rubber tape is adhered to the desired location. A method for manufacturing shoes having a foamed polyurethane outsole, characterized in that each adhesive and unvulcanized rubber tape are vulcanized using heated and pressurized air.