JP2003135105A - Boots made of foamed resin - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent such a failure that sole segments are too soft and soles are liable to wear in manufacturing made of, for example, a lightweight and thin foamed resin by injection molding. SOLUTION: An outsole part 3 of about 1.5 mm in base thickness is molded of a non-foamed solid-form soft polyvinyl chloride resin and thereafter this outsole part 3 is set into the sole segment of the cavity space C of an injection mold 4 and a boot body molding material prepared by compounding thermal expansion type microcapsules with the soft polyvinyl chloride resin is injected into the cavity space C to expand, inject and mold a boot body 2 and is integrated with the outsole part 3, by which the boot 1 made of the light weight foamed resin is molded.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a foamed resin boot molded by injection molding.

[0002]

2. Description of the Related Art Conventionally, an injection-molded boot is wholly made of a solid synthetic resin, so that it is heavier than general shoes and the like, and when used for a long period of work, The user was tired easily.
Therefore, in order to reduce the weight, the main body of the entire boot excluding the outsole portion is injection-molded, and only the outsole of the boot body is manufactured by using another lightweight material such as EVA. The thing which the bottom was adhere | attached and was integrated was produced.
However, the one manufactured by adhering another member in this way has been insufficient in weight reduction only in the outsole, and was insufficient in terms of weight reduction. Moreover, when the used boots are discarded and recycled as the resin raw material, it is necessary to separate the main body and the outsole, which are different materials. Therefore, the present inventors have proposed an injection molding technique suitable for manufacturing a lightweight boot such as Japanese Patent Application No. 2000-156647 in order to further reduce the weight of the injection molded boot. Generally, in an injection-molded boot, the last mold that is a male mold is inside, the side mold that is a female mold is outside, and a synthetic resin is injected into a void portion of the boot to mold the resin.
It was generally provided on the bottom surface of the book, which is the design surface.
For this reason, since the outsole portion is thicker in resin than other main body portions, in order to completely fill the whole, it is necessary to make the filling pressure larger than that of a general injection molding shoe.
Therefore, even if the foaming agent is added to the synthetic resin and foam-molded, the foaming agent does not sufficiently foam and the weight cannot be reduced.
Furthermore, if the thickness of the boot body is reduced to reduce the weight,
The filling pressure was further increased, and the resin was hardly foamed. Therefore, in this technology, by providing an injection hole in the main body portion that is thinner than the outsole, the filling pressure can be kept low, the foaming agent can be sufficiently foamed, and the boot can be made thinner. It was done.

[0003]

By the way, when a boot is manufactured by applying the above-mentioned technique, it is possible to manufacture an extremely lightweight boot in which the entire body including the thin portion of the main body is foamed. Especially when the overall thickness is reduced to reduce weight, the sole part may become too soft, or the sole may be easily worn, resulting in poor durability depending on the application of the boot. However, there was a problem that the tendency increased.

Therefore, the present invention has an object to prevent problems such as the sole portion being too soft and the shoe sole being easily worn when manufacturing a thin and lightweight foamed resin boot by injection molding. .

[0005]

In order to achieve the above-mentioned object, the present invention is to provide a solid outsole at least in a heel portion and a tread portion in a sole portion of a boot body made of a foamed resin molded by injection molding. I tried to integrate the parts.

Here, the solid part is a material part that is not foamed and is filled with solid material. The boot body is foamed to reduce the weight, and the sole part has hardness to the sole part. It can be held and the abrasion resistance can be improved. Further, the outsole parts are provided on at least the heel portion and the stepping portion of the sole portion where they often come into contact with the floor surface or the like, but may be provided on the entire sole portion. As the resin material for the boot body, for example, a soft polyvinyl chloride (PVC) resin is suitable, and for the outsole parts, it can be integrated with the boot body, and has abrasion resistance, slip resistance, and bending. Material with excellent properties,
For example, rubber materials such as polyvinyl chloride resin, natural rubber, and synthetic rubber are suitable. It is preferable that the boot body and the outsole parts are made of the same synthetic resin because the recyclability is improved.

Further, in the present invention, the outsole parts are integrated when the boot body is injection-molded.

In this way, if the outsole parts are integrated during injection molding of the boot body, it can be manufactured efficiently. here,
As a method of integrating the outsole parts at the time of injection molding of the boot body, for example, so-called two-color molding, in which the insole part is injection-molded by using a dummy mold, and then the mold is reassembled to form the boot body A method such as positioning the molded outsole part at a predetermined position in the cavity and injection-molding the boot body is applicable. At this time, the thickness of the outsole part can be appropriately determined depending on the use of the boot and the like, but in terms of weight reduction and water resistance, the base thickness excluding the design portion is about 1.0 to 3.0 mm. Is desirable.

Further, in the present invention, when the boot body made of foamed resin is foamed, thermal expansion type microcapsules are used for foaming. Here, for example, when foaming using a thermal decomposition type foaming agent, an unfoamed skin layer is generated in a portion in contact with the molding die, so that the foamed region is extremely narrow in the thin portion and there is a limit to weight reduction, In addition, a long cooling time is required because secondary foaming tends to continue.
Therefore, by using a thermal expansion type microcapsule for foaming, unlike a pyrolysis type foaming, for example, a skin layer is not formed on the surface portion, and even a portion in contact with the mold is foamed for further weight reduction. In addition to the advantages, it is possible to achieve more uniform foaming, suppress secondary foaming that continues foaming after injection molding, and shorten the cooling time after molding. In addition, due to the weight reduction of the thermal expansion type microcapsule by foam molding,
Although the durability and water resistance of the outsole are reduced, by using the outsole part of the present invention, a good foamed resin boot can be obtained.

Here, the thermal expansion type microcapsule is, for example, one in which a swelling agent such as propane, butane, pentane, isopentane is contained in a spherical resin shell and expands several times to several tens times by heat. Is preferred.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described with reference to the accompanying drawings. Here, FIG. 1 is an explanatory view showing an example of a foamed resin boot according to the present invention, FIG. 2 shows outsole parts, (a) is a side view, (b) is a bottom view, and FIG. 3 is an injection molding mold. Explanatory drawing, FIG. 4 is explanatory drawing of the state which clamped the said injection molding mold.

The foamed resin boot 1 according to the present invention has a problem that the sole portion is too soft and the shoe sole is easily worn when a thin and lightweight boot is manufactured by injection molding with a foamed resin. To prevent the
As shown in FIG. 1, a solid outsole part 3 is integrated with a sole portion of a boot main body 2 made of foamed resin so that the sole portion has hardness and abrasion resistance is improved. .

Here, the boot body 2 made of foamed resin is preferably applied to the boot body 2 when it is molded by the injection mold 4 as proposed in Japanese Patent Application No. 2000-156647 by the present applicant. Yes, it can be molded extremely lightweight. Therefore, the injection mold 4 will be described first.

The injection mold 4 is shown in FIG.
As shown in (a), a last mold 5 having a foot shape.
And a pair of left and right side molds 6 surrounding the sides of the last mold 5 and a bottom mold 7 surrounding the periphery of the lower surface of the last mold 5. In the mold clamping state, the cavity space part as shown in FIG. It is designed to define C.

A material injection passage 8a (FIG. 4) extending vertically is formed in the middle of the bottom mold 7.
Further, on the upper surface of the bottom mold 7, a groove 8b (FIG. 3) communicating with the material injection passage 8a is engraved toward the toe side.

Further, on the left and right side molds 6, a groove 8c connectable to the toe side extending end portion of the groove 8b is formed upward, and the extending end portion of the groove 8c is a gate groove 8g.
It is connected to. Then, when the left and right side molds 6 are clamped, the grooves 8c and the gate grooves 8g of the left and right side molds 6 are overlapped with each other to form a flow path and a gate of a molding material. It is designed to open toward the thin width portion of.

Therefore, when the foam molding material is injected from the material injection passage 8a in the mold clamped state, the molding material is filled with the groove 8a.
The cavity width portion C is filled from the thin-walled molded portion of the boot toward the thick-walled molded portion of the boot via b, 8c and the gate groove 8g, and the gap width of the cavity space portion C is reduced as a whole. Even when molding a thin and lightweight boot, it is possible to uniformly foam the foam with a low filling pressure.

Injection mold 4 as described above
A method of manufacturing the foamed resin boot 1 using is described. First, the outsole part 3 as shown in FIG. 2 is molded.
Here, as the outsole part 3, a solid one such as soft polyvinyl chloride resin or rubber (not foamed but filled with contents) can be applied, but in this embodiment, soft vinyl chloride is used. The resin is molded by press molding, and its form is such that the entire boot bottom is covered from the toe part to the heel part, as shown in FIG. Here, the form of the outsole part 3 may be an arbitrary form as long as it includes a stepping part and a heel part that often come into contact with the floor surface during walking or the like. It may be divided into a heel part and a heel part, and each part may be locally covered. The molding method may be injection molding instead of press molding.

The bottom side design of this outsole part 3 is
The bottom mold 7 has the same design as the boot bottom, and as described below, when the main bottom part 3 is positioned on the bottom mold 7 and the boot body 2 is injection-molded, the main bottom part 3 is displaced. I try not to wake it up.

The thickness t of the base portion of the outsole part 3 other than the design convex portion is in the range of 1.0 to 3.0 mm and is about 1.
It is set to 5 mm. If the thickness t is less than 1.0 mm, the durability will be deteriorated due to abrasion and the like.
If it exceeds 0 mm, the weight tends to increase and the flexibility tends to decrease.

The outsole part 3 as described above is shown in FIG.
As shown in FIG. 4, when the bottom mold 7 is positioned on the sole portion and the mold is clamped, the cavity space portion C is formed in the state as shown in FIG. Then, the boot body 2 is molded by injecting the boot body molding material into the cavity space C and integrated with the outsole part 3.

Here, in this embodiment, the boot body molding material is a composition in which a resin containing soft polyvinyl chloride (PVC) as a main component is mixed with thermal expansion microcapsules. And as a thermal expansion type microcapsule,
Swelling agents such as propane, butane, pentane, and isopentane are encapsulated inside the spherical resin shell, and those that expand several times to several tens of times by heat are preferable, and in the examples, acrylonitrile copolymer Commercially available Matsumoto Microsphere F with isopentane inside the shell
-110D (Matsumoto Yushi-Seiyaku Co., Ltd.) or EXPANCEL
092-120 DU (manufactured by EXPANCEL) is used in a total composition of 10
3 to 10 parts by weight relative to 0 parts by weight, more preferably 6 to
8 parts by weight are blended.

The boot body molding material as described above is melted at, for example, 190 to 200 ° C., and the material injection passage 8 is formed.
When injected from a, the molding material is injected into the cavity space C through the grooves 8b and 8c and the gate groove 8g, and at the same time as the injection, the thermal expansion type microcapsules expand and foam to form the boot body 2. At the same time as the boot body 2 is manufactured, the outsole part 3 is integrated with the boot body 2. Further, this foaming uniformly foams up to the surface layer even in the thin portion of the product, and since there is almost no secondary foaming, the cooling time is short. When the molded product is cooled and then taken out of the mold, the foamed resin boot 1 as shown in FIG. 1 is manufactured.

In the foamed resin boot 1 manufactured as described above, the sole of the shoe does not easily wear even when worn for a long period of time, durability is improved, and hardness of the sole portion is increased. It also has excellent slip resistance and is comfortable to wear.

In the above embodiment, in order to integrate the outsole part 3 and the boot body 2, the press-molded outsole part 3 is positioned and set in the bottom mold 7, and the boot body 2 is injection molded. Although shown, it is also possible to perform so-called two-color molding in which the bottom part 3 is injection-molded using a dummy mold and then the boot body 2 is injection-molded by remolding.

The present invention is not limited to the above embodiment. Those having substantially the same configurations as those described in the claims of the present invention and exhibiting the same operational effects belong to the technical scope of the present invention. For example, the materials and shapes of the boot body 2 and the outsole part 3 are examples.

[0027]

As described above, the foamed resin boot according to the present invention has a solid outsole at least at the heel and the foot of the sole portion of the foamed resin boot body molded by injection molding. Since the parts are integrated, it is possible to add hardness to the sole part of the lightweight boot and to improve wear resistance. At this time, if the outsole parts are integrated at the time of injection molding of the boot body, it can be efficiently manufactured. Further, when foaming the boot body made of foamed resin, if foaming is performed by using the thermal expansion type microcapsule, for example, compared to a pyrolysis type foaming agent, it is possible to foam up to the part in contact with the molding die to further reduce the weight. It is possible to achieve more uniform foaming, suppress secondary foaming, and shorten the cooling time.

[Brief description of drawings]

FIG. 1 is an explanatory view showing an example of a foamed resin boot according to the present invention.

FIG. 2 shows outsole parts, (a) is a side view and (b) is a bottom view.

FIG. 3 is an explanatory view of an injection molding mold, (a) shows a state before the bottom part is set, and (b) shows a state where the bottom part is set.

FIG. 4 is an explanatory view of a state where the injection molding mold is clamped.

[Explanation of symbols]

1 ... Foamed resin boot, 2 ... Boot body, 3 ... Outsole parts, 4 ... Injection mold.

Claims (3)

[Claims] 1. A boot main body made of foamed resin molded by injection molding, and a solid outsole part which is integrated with at least a heel portion and a foot portion of a sole portion of the boot main body. A boot made of foamed resin. 2. The foamed resin boot according to claim 1, wherein the outsole parts are integrated when the boot body is injection-molded. 3. The foam resin boot according to claim 1, wherein the foam resin boot body is foamed by using thermal expansion microcapsules.