JPH0319053B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention is a synthetic resin molded product whose core material is an open-celled rigid polyurethane foam with an open cell rate of 50 to 100%, and is suitable for applications such as interior and exterior materials of automobiles. The present invention relates to a method for producing a synthetic resin molded article having the following. [Prior art] Synthetic resin molded bodies using polyurethane foam as a core material are manufactured using polyurethane foam as a core material for the purpose of reducing the weight of the molded body while maintaining shape retention during molding. Since rigid polyurethane foam is usually used as the core material, closed cell foam with a high expansion rate of 5 to 30 times and an open cell rate of 5% or less is used. has been done. By the way, the polyurethane foam used in synthetic resin moldings with this rigid polyurethane foam as the core material is produced by, for example, mixing water when mixing two liquids of polyol and isocyanate, generating carbon dioxide gas, and expanding the foam. It can be obtained by performing foam molding using pressure, or by mixing a vaporizable liquid such as freon when mixing the two liquids mentioned above, vaporizing it using the heat of reaction, and performing foam molding using the expansion pressure. is common, and the polyurethane raw material is injected into a normally closed mold,
It is molded as a polyurethane foam molded product in a predetermined shape. Therefore, in the obtained polyurethane foam, the blowing agent gas and vaporized liquid remain in the cells of the foam, and the pressure of the gas in the cells of the foam is 1.5 to 3. The pressure is above atmospheric pressure, which is about atmospheric pressure. In the conventional manufacturing method, in which this polyurethane foam is inserted into a mold in advance and the synthetic resin is molded using the mold, a synthetic resin molded article with the molded polyurethane foam as a core material is Over time, especially when exposed to high-temperature atmospheres, not only the gas remaining in the cells of the foam, but also the vaporized liquid will become foamed. It dissipates outside the body and stays at the interface between the core foam and the synthetic resin coating layer formed on the outer surface of the foam. In this way, in a synthetic resin molded body having a rigid polyurethane foam as a core material, a cavity is generated at the interface between the core material and the synthetic resin coating layer due to the above-mentioned retained gas, and a "bulge" is generated on the surface of the molded body. The shape retention of the molded product deteriorated significantly, and deformation usually remained even at room temperature. Therefore, in order to suppress the formation of "bulges" in the synthetic resin molded product having the polyurethane foam as a core material, the polyurethane foam is heated in advance at a high temperature for a long period of time to cause the polyurethane foam to remain in the cells of the foam. Methods for dissipating gases; methods for maintaining polyurethane foam under reduced pressure, such as by leaving it in a vacuum box, to reduce the pressure within the cells of the foam; By sanding the surfaces of both the synthetic resin coating layer and the synthetic resin coating layer formed to cover it, the adhesion between the two is improved, and the gas that has remained in the cells of the polyurethane foam is removed. Attempts have been made to dynamically suppress the resulting expansion pressure. However, in the above method, there is a significant increase in cost when carrying out the operation;
The desired "blister" prevention effect may not be sufficient, or the intended use of the resulting synthetic resin molded product may be
At present, it has drawbacks such as being subject to limitations due to its structure. [Problems to be Solved by the Invention] The present invention provides a molded article consisting of a core material made of a rigid polyurethane foam and a synthetic resin coating layer covering the core material. It has the characteristics that the bonding stability between the two is high, and even if the synthetic resin molded product is exposed to a high temperature atmosphere, the dimensional stability of the molded product during molding can be maintained. An object of the present invention is to provide a method for manufacturing a synthetic resin molded body that can [Means for Solving the Problems] In order to solve the above-mentioned problems, the present invention molds the core material of the synthetic resin molded body to be manufactured using an open-celled rigid polyurethane foam with an open cell rate of 50 to 100%. A first step, a second step of arranging the core material in the mold, closing the mold, injecting a synthetic resin for forming a coating layer, curing the coating layer by reaction or cooling, and then releasing the mold. A configuration is adopted in which a synthetic resin molded body is molded through a third step and a fourth step in which a plurality of small holes are bored in the synthetic resin coating layer of the obtained molded body to reach the core material. [Function] In the present invention, after manufacturing a molded article in which a core material of an open-cell rigid polyurethane foam with an open cell rate of 50 to 100% is covered with a synthetic resin coating layer, the core material is added to the coating layer. By simply adding the step of drilling multiple small holes that reach the core material, the gas stagnant in the cells of the rigid polyurethane foam that is the core material can be removed from the interface between the core material and the synthetic resin coating layer in the synthetic resin molded product. A molded body is obtained which further penetrates the synthetic resin coating layer and dissipates to the outside of the synthetic resin molded body, and a "blister" phenomenon is caused by the dissipation of the gas that has remained in the cells of the rigid polyurethane foam that is the core material. This is an extremely effective way to prevent The rigid polyurethane foam used as the core material in the present invention is a so-called open-cell foam molded from a molding raw material mixed with an opening agent appropriately when molding the polyurethane foam.
Preferably, those having an open cell rate of 50 to 100% are used. The synthetic resin coating layer that completely covers the core material made of the open-celled rigid polyurethane foam may be made of, for example, polyolefin such as polyethylene or polypropylene, polyamide, polystyrene,
It is made of synthetic resins used in general synthetic resin moldings, such as ABS resin and fiber-reinforced unsaturated polyester synthetic resins. The synthetic resin molded product having a rigid polyurethane open-cell foam as a core material manufactured by the present invention is produced in exactly the same manner as the conventional synthetic resin molded product having a polyurethane foam core material, that is, a predetermined A polyurethane open-cell foam having a shape of However, the holes for air release provided in the synthetic resin coating layer are approximately 4 mm deep in an inconspicuous part of the synthetic resin molded body.
It is preferable to form perforated holes with a diameter of about 50 cm at intervals of about 50 cm. [Example] Next, a specific method for manufacturing a synthetic resin molded article having a core material of an open cell foam of rigid polyurethane having an open cell rate of 50 to 100% will be described based on illustrated examples. FIG. 1 is a perspective view showing a back door for an automobile, which is an example of a synthetic resin molded product whose core material is an open-cell rigid polyurethane foam with an open cell rate of 50 to 100%, manufactured according to the present invention. , and FIG. 2 shows A of the automobile back door shown in FIG. 1.
- A sectional view, and FIG. 3 is a BB sectional view. The automobile back door 1 shown in the figure includes a core material 2 made of hard polyurethane foam with an open cell rate of approximately 99% and having a thickness of about 10 to 40 mm, and a core material 2 that covers the entire outer surface of the core material 2. A synthetic resin coating layer 3 with a thickness of approximately 2 mm, which is a glass fiber-reinforced unsaturated polyester resin layer, is laminated and adhered to the core material 2 described above.
In the synthetic resin coating layer 3, a perforated hole for air release as indicated by reference numeral 4 in FIG. 3 is formed so as to penetrate the synthetic resin coating layer 3. This is what has been done. This hole for air release should be approximately 4mm in diameter.
Eight pieces are formed at intervals of about 50 cm on the back side of the back door 1 for an automobile, but since they are formed in a relatively invisible part, that is, on the inner side of the back door, they do not spoil the appearance of the back door 1 for the car in any way. It's not a thing. In the present invention, as a first step, the core material 2 in the automobile backdoor 1 is formed according to the procedure for molding a normal polyurethane foam using a composition having the composition shown in Table 1 below. Manufacture. Then, an unsaturated polyester resin obtained from ethylene glycol, maleic anhydride, and isophthalic acid is applied to the surface of the resin injection mold for molding the automobile back door 1.
A composition consisting of 100 parts by weight, 30 parts by weight of styrene, 1 part by weight of methyl ethyl ketone peroxide, and 0.6 parts by weight of cobalt naphthenate was spray applied to form a gel coat layer with a thickness of 0.3 mm.
Next, in the second step, a glass fiber preform with a thickness of 2 mm and a core material made of the above-mentioned rigid polyurethane foam with a thickness of 10 to 40 mm are sequentially laminated on the gel coat layer formed in the previous step. do. Next, in the third step, the lower and upper molds of the mold are closed together, unsaturated polyester resin is injected through the injection hole, and the mold is released about 30 minutes after the third step is completed. After demolding, air reaches the core material, a hard polyurethane foam with an open cell rate of 50 to 100%, by drilling round holes at predetermined positions on the back side of the injection molded product obtained in the fourth step after demolding. Form a hole for escape.

[Table] Comparative Example A rigid polyurethane foam with an open cell rate of approximately 1% was molded using a composition having the composition shown in Table 2 below, and the resulting rigid polyurethane foam was used as a core material. Synthetic resin molded bodies A and B were manufactured for comparison. The method for producing the synthetic resin molded bodies A and B includes two steps: changing the type of hard polyurethane foam serving as the core material, and omitting the fourth step in the production example of the automobile back door 1 of the above embodiment. The manufacturing process for the automobile backdoor 1 is different from the manufacturing process of the automobile back door 1 in the above-mentioned embodiment, and the other steps are completely the same. However, for the synthetic resin molded body A, the molded rigid polyurethane foam is heated at 80°C in advance.
A material that has been subjected to a heat treatment for 120 minutes to dissipate the gas inside the cells is used as a core material.Synthetic resin molded body B uses the molded rigid polyurethane foam as it is as a core material. This is what I used.

[Table] Confirmation of effect Automobile back door 1 obtained in the above example
The synthetic resin molded product A (automobile back door) and the synthetic resin molded product B (automobile back door) obtained in the comparative example were heated to 80°C.
After leaving the product in an atmosphere of There was no occurrence of "bulge". However, the back door for an automobile, which is the synthetic resin molded product A, has "bulges" as shown by reference numeral 5 in FIG. A ``bulge'' with a maximum distance ``H'' of approximately 1 mm remained. In addition, the synthetic resin molded body B, which is an automobile back door, has a reference numeral 6 in FIG.
There remains a "bulge" as shown in , that is, a "bulge" in which the maximum distance "h" between the surface of the core material 9 and the back surface of the synthetic resin coating layer 10, which is a glass fiber reinforced unsaturated polyester resin layer, is approximately 5 mm. Ta. [Effects] The method for producing a synthetic resin molded body using a rigid polyurethane open-cell foam with an open cell rate of 50 to 100% as a core material according to the present invention has the above-mentioned configuration. Cell rate 50-100
% open-celled rigid polyurethane foam, and the synthetic resin layer that entirely covers the core material is configured to have perforated holes for air release that penetrate the synthetic resin layer. Therefore, even if the manufactured synthetic resin molded body is left in a high-temperature atmosphere, the gas remaining in the cells of the foam will be released from the foam to the outside. Since the air is smoothly dissipated through the air release holes and is dissipated out of the synthetic resin molded body through the air escape holes, there is no "bulging" caused by gas remaining in the cells of the foam, which improves dimensional stability. It is possible to produce a synthetic resin molded article that exhibits an excellent effect, and the production cost is not particularly high, and it also has the effect that it can be produced at a low cost.

[Brief explanation of drawings]

FIG. 1 is a perspective view of an automobile back door which is an example of a synthetic resin molded product having an open-cell rigid polyurethane foam as a core material of the present invention, and FIG. 2 is a sectional view taken along the line A-A in FIG. Figure 3 is a cross-sectional view taken along the line B-B in Figure 1, and Figures 4 and 5 are cross-sectional views of different automobile back doors showing the state of ``bulge'' that occurred in the automobile back doors manufactured as comparative examples. be. 1: Automobile back door, 2: Core material made of open-cell hard polyurethane foam, 3: Synthetic resin coating layer, 4: Perforated holes for air release.

Claims (1)

[Claims] 1. A first step of molding the core material of the synthetic resin molded body to be manufactured using an open cell foam of rigid polyurethane with an open cell rate of 50 to 100%, and a second step of arranging the core material in a mold. The third step is to close the mold, inject the synthetic resin for forming the coating layer, harden the coating layer by reaction or cooling, and then release the mold, and reach the core material in the synthetic resin coating layer of the obtained molded body. A method for manufacturing a synthetic resin molded body having a rigid polyurethane open-cell foam as a core material, comprising a fourth step of drilling a plurality of small holes.