JPS6248981B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a new method for manufacturing products using urethane foam molded products. Urethane foam molded products are generally manufactured by mixing two liquids, polyol and isocyanate, with water, and foaming the mixture under the expansion pressure of the generated carbon dioxide gas. Therefore, in the resulting urethane foam molded product, the generated carbon dioxide gas remains in the foam cells, and the more closed cells there are, the greater the amount remains. In the case of products that use urethane foam molded products in which such carbon dioxide gas remains, such as fiber reinforced plastic (hereinafter simply referred to as FRP) molded products that use urethane foam molded products as a core material, if they are exposed to high temperatures, The carbon dioxide gas escaping from the cells of the core material of the urethane foam molded product interacts with the core material.
concentrated at the boundary between the FRP layer and the resulting core material and FRP
There is a problem in that cavities are formed between the layers, causing blisters on the surface of the FRP molded product, and causing abnormalities in the dimensions of the product. Methods to prevent such blistering include heating the urethane foam molded product for a long time at around 50°C to dissipate carbon dioxide gas from the cells in advance, and improving the adhesion between the urethane foam molded product and the FRP layer. Attempts have been made to improve this and physically suppress the separation of the two due to expansion of carbon dioxide gas. However, these attempts have problems such as increased cost, lack of blistering prevention effect, and limited use conditions of the product. In the above, the problem of blistering in products using urethane foam molded products was discussed with respect to FRP molded products, but the same problem also applies to molded products of other resins, such as polyethylene, polypropylene, polyamide, ABS resin, etc. There is a problem. A similar problem also occurs in a structure in which a urethane foam molded product used as a heat insulating material in a drying oven is sealed with a steel plate. However, as a result of extensive research into ways to prevent blistering in products using urethane foam molded products, the present inventors found that by adding an alkaline substance to the urethane foam molded product, carbon dioxide gas released from the cells due to heat can be prevented. The present invention was completed by discovering a new fact that carbon dioxide gas is quickly neutralized and changed into a liquid or solid substance, and gaseous carbon dioxide is eliminated, thereby preventing the occurrence of blisters. . That is, the present invention provides a method for producing a product using a urethane foam molded product, which comprises completely or partially wrapping the urethane foam molded product with a material that is substantially impermeable to carbon dioxide. The present invention relates to a method for producing a product using a urethane foam molded product, which is characterized by the presence of an alkaline substance capable of neutralizing gas. However, in the present invention, blistering in products using the urethane foam molded product can be completely prevented by a simple configuration in which an alkaline substance is present in the urethane foam molded product. It is extremely advantageous in terms of cost, anti-blister effect, and product usage. The urethane foam molded product referred to in the present invention is a foam molded product of a polymer compound having urethane bonds, and its foaming is mainly dependent on carbon dioxide gas, and by using carbon dioxide gas and other blowing agents in combination. It also includes urethane foam molded products. It also includes both soft and hard molded products. The alkaline substance used in the present invention is not particularly limited as long as it can react with carbon dioxide gas and convert into a liquid or solid substance, but examples include alkali metal hydroxides such as sodium hydroxide and potassium hydroxide, and calcium hydroxide. , alkaline earth metal hydroxides such as magnesium hydroxide, alkaline earth metal oxides such as calcium oxide and magnesium oxide, amines such as ethylenediamine, diethylenetriamine, triethylenetetramine, trimethylenediamine, tetramethylenediamine, and ethanolamine. etc. are used. The alkaline substance may be present in the urethane foam molded product, for example, by applying or adhering it directly to the surface of the molded product or in a groove provided on the surface, or by applying it directly to the inside of the molded product or through a hole provided therein. Examples include methods of injecting into When applying, attaching or injecting alkaline substances, whether the alkaline substance is solid or liquid,
It can be used as it is, or it can be dispersed or dissolved in water or an organic solvent. The amount of the alkaline substance present in the urethane foam molded product may be an amount that can substantially neutralize carbon dioxide gas present in the urethane foam molded product or more. The amount of carbon dioxide gas present in a urethane foam molded product varies depending on the foaming ratio of the molded product, etc., but a test piece of a certain size is cut out from the molded product and the amount of carbon dioxide gas is determined by gas chromatography etc. , the amount of alkaline substances to be used can be determined based on that value. Note that in urethane foam molded products, the amount of carbon dioxide gas varies somewhat depending on the skin layer and inner layer of each product used, so it is desirable to ultimately decide on a trial basis for each urethane foam molded product to be used. The product using the urethane foam molded product according to the present invention is a product in which the molded product is completely or partially wrapped in a material that is substantially impermeable to carbon dioxide, and specifically, it is used for automobile panels. and parts, and panels used as insulation for drying ovens. Examples of the carbon dioxide impermeable material include polyethylene, polypropylene, polyamide, ABS resin, and unsaturated polyester resin, and these resins may be used in combination with reinforcing fibers. The molding methods for final products using these resins include hand lay-up method,
Spray up method, resin injection method,
Injection molding methods are used. In addition to the above-mentioned resin materials, examples of carbon dioxide impermeable materials include metal plates such as steel and iron. Next, the method of the present invention will be explained with reference to Examples and Comparative Examples. Examples 1 to 4 and Comparative Example 1 FRP using hard urethane foam molded product as core material
The back door of an automobile shown in FIGS. 1 to 3 was manufactured by the resin injection method described above. 1 is a plan view of the back door, FIG. 2 is an enlarged sectional view taken along the line AA in FIG. 1, and FIG. 3 is an enlarged sectional view taken along the line BB in FIG. 1. In Figures 1 to 3, 1 is the core material of the urethane foam molded product, and 2 is the FRP layer. The core material used had an average thickness of 20 mm, a total volume of 10,000 cm ³ , and contained 18 g of carbon dioxide gas. The lower mold of the FRP mold for resin injection molding is made of unsaturated polyester resin (ethylene glycol,
100 parts (parts by weight, same hereinafter) of unsaturated polyester obtained from maleic anhydride and isophthalic acid,
30 parts of styrene, 1 part of methyl ethyl ketone peroxide, and 0.5 parts of cobalt naphthenate) was spray applied to form a 0.3 mm thick gel coat layer (this gel coat layer will be the outer surface of the resulting final product). Next, on top of this gel coat layer, a glass fiber preform and a core material to which an alkaline substance was added as shown in Table 1 (but not in Comparative Example 1) were set, and the lower mold and upper mold were closed, and the injection hole was closed. 6 kg of a more unsaturated polyester resin (consisting of 100 parts of an unsaturated polyester obtained from ethylene glycol, maleic anhydride and phthalic anhydride, 30 parts of styrene, and 1 part of methyl ethyl ketone peroxide)
It was injected at an injection pressure of cm ² and released from the mold after 30 minutes to obtain an FRP back door with a hard urethane foam molded product as the core material. The average thickness of the FRP layer was 2.5 mm. In addition, in the above, the amount of alkaline substance added to the core material is the total amount of carbon dioxide contained in the core material (18g)
The neutralization equivalent of

[Table] Examples 1 to 4 in which the obtained backdoors were heated at 80°C for 8 hours and an alkaline substance was added.
In Comparative Example 1, no blistering was observed at the interface between the core material and the FRP layer, but as shown in Figure 4 (corresponding to Figure 2) and Figure 5 (corresponding to Figure 3), Comparative Example 1 did not contain any alkaline substances. A lot of blisters occurred. The degree of blistering [the maximum distance H between the separated core material and the FRP layer shown in FIGS. 4 and 5] was about 10 mm. Examples 5 to 8 and Comparative Example 2 The same rigid urethane foam molded product (40 mm thick) used in Examples 1 to 4 was wrapped in a 0.5 mm thick steel plate to produce a panel for a drying oven. Examples 5-8
The type of alkaline substance, usage conditions, and application method were the same as in Examples 1 to 4 (however, in Comparative Example 2, no alkaline substance was applied). When each of the resulting panels was heated at 100°C for 10 hours, no blisters were observed in Examples 5 to 8, but blisters occurred in Comparative Example 2, and the extent of the blisters was approximately 5 mm. .

[Brief explanation of the drawing]

Figure 1 uses a urethane foam molded product as the core material.
A plan view of the FRP back door, Fig. 2 is an enlarged sectional view taken along the line AA in Fig. 1, Fig. 3 is an enlarged sectional view taken along the line B-B in Fig. 1, and Figs. 4 and 5 show the back door. FIG. 3 is a cross-sectional view showing the state of blisters after heating, and corresponds to FIG. 2 and FIG. 3, respectively. Main symbols in the drawing: 1: Core material of urethane foam molded product, 2: FRP layer.

Claims (1)

[Claims] 1. In a method for manufacturing a product using a urethane foam molded product, which consists of completely or partially wrapping the urethane foam molded product with a material that is substantially impermeable to carbon dioxide gas, the urethane foam molded product is neutralized with carbon dioxide gas. A method for producing a product using a urethane foam molded product, which is characterized by the presence of a potentially alkaline substance.