JP2879862B2 - Method for imparting an uneven pattern to urethane foam - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for forming fine irregularities on the surface of a soft or semi-rigid urethane foam in injection foam molding, and more particularly, to a method of fixing the surface of an automobile floor carpet as a cushioning material to the back surface thereof. This method is suitable for urethane foam.

[0002]

2. Description of the Related Art Conventionally, it has been widely practiced to obtain a soft or semi-rigid urethane foam by injection foam molding.

[0003] This is a method called cold cure, in which a pair of upper and lower dies having a cavity conforming to the shape of a target molded product are completely clamped, or in a half-clamped state, polypropylene glycol or the like is used. A liquid mainly composed of polyols and a B liquid of isocyanates such as methylene diisocyanate are injected at low or medium pressure, and the foaming, crosslinking and polymerization reactions of both liquids are allowed to proceed between the molds.
After almost completing the reaction within a few minutes, demold,
A required foam molded article is obtained.

[0004] By this type of injection foam molding, a foam molded article conforming to the cavity of the mold can be easily obtained.

[0005] If it is desired to give a fine uneven pattern to this type of foam molded article for the purpose of laying property, decorativeness, weight reduction, etc., conventionally, a required uneven pattern is given to the mold shape. It was necessary to make such a change, and the production of the mold required cost and man-hour.

Further, when the shape of the mold is complicated, it is difficult to sufficiently apply a mold release agent to the mold and perform regular cleaning of the mold, which are indispensable in this type of injection mold.

[0007]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and it is possible to impart a required minute uneven pattern to a foamed molded article with a simple structure and to easily maintain a mold. Provide a way.

[0008]

According to the present invention, there is provided an injection molding method of a soft or semi-rigid urethane foam, which is performed before the injection of the urethane resin into the injection mold. At least on a part of the surface, a flexible polyethylene resin sheet having a large number of microprojections is fixed, and then the urethane resin is injected into the mold to form the foam. By peeling, the urethane foam is provided with an uneven pattern.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below with reference to the drawings.

FIGS. 1 to 3 show an embodiment based on the present invention, and show a method of integrally forming a urethane foam provided with a fine uneven pattern on a back surface of an automobile floor carpet as a cushioning material.

First, as shown in FIG. 1, a pair of upper and lower urethane injection molds having a cavity corresponding to a required foam molded article are opened, and an automobile floor carpet formed on a lower mold is placed with its surface facing downward. .

Also, a flexible sheet of polyethylene resin having a plurality of protrusions is fixed to the upper mold with the surface having the protrusions facing downward.

This sheet is formed by regularly arranging flat hollow cylindrical projections having a height of about 5 mm and a diameter of about 20 mm, which are generally used for packing and the like, at regular intervals.

A preferred method of fixing the sheet to the upper die is a method of vacuuming the upper die as a vacuum forming die.

Next, as shown in FIG. 2, the injection mold is clamped, and both A and B liquids mainly containing polyols and isocyanates are injected into the mold from an injection port (not shown), and a foaming reaction is performed. To fill the cavity.

After the reaction is completed (about 1 minute), the urethane foam is integrally formed as a cushioning material on the back surface of the carpet (apparent density: 0.09 g / cm ³ ) by demolding.

Thereafter, as shown in FIG. 3, by peeling the polyethylene resin sheet from the surface of the foam,
An uneven pattern is imparted to the foam.

[0018]

According to the present invention, a required fine uneven pattern can be provided on the surface of the urethane foam with a simple structure.

In addition to cleaning the mold, the step of applying a release agent to the mold surface can be omitted.

[Brief description of the drawings]

FIG. 1 shows an arrangement state on an injection mold.

FIG. 2 shows a urethane resin injection step.

FIG. 3 shows a state in which the sheet is peeled off.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Urethane foam 2 Injection mold 3 Polyethylene resin sheet 4 Micro projection 5 Car floor carpet 6 Cavity

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code FI B29L 31:58

Claims (1)

(57) [Claims] 1. In the injection foaming of a soft or semi-rigid urethane foam, prior to injection of a urethane resin into the injection mold, flexible polyethylene having a large number of microprojections on at least a part of the surface of the injection mold. Fixing the resin sheet, then injecting urethane resin into the mold, foam molding, and peeling off the resin sheet from the foam obtained by demolding, thereby imparting an uneven pattern to the urethane foam. Method for imparting a concavo-convex pattern characterized by the following