JPH0550367B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Application Fields] The composite molded product of the present invention can be used as lining insulation materials for the main body and doors of refrigerators, door materials for show window cases and unit baths that require heat insulation, and automobiles that require cushioning properties. It is useful as automobile interior materials such as bumpers and door trims, surfboards, etc. [Prior art] Acrylonitrile-butadiene-styrene copolymer, which is a styrene resin, is used for the body and doors of refrigerators to prevent rust on the baking-painted stainless steel or steel plate manufacturing base material (outer frame) and to form shelves. (Commonly known as "ABS") sheet is provided with a lining material obtained by vacuum forming, pressure forming, or forming using a combination of vacuum and pressure (hereinafter, these forming methods are collectively referred to as thermoforming). Furthermore, instead of the ABS lining material, it has been proposed to use a polypropylene lining material with excellent surface gloss and low water absorption. In order to improve the heat insulation properties of these lining materials, it has been proposed to interpose polyurethane foam between the structural base and the lining material (Japanese Patent Laid-Open No. 60-97841).
issue). Additionally, the door materials for unit baths are currently made from polyvinyl chloride sheets, but when used at high temperatures, the aluminum sash frame corrodes due to the chlorine gas generated by decomposition, so improvements have been made to this issue. Therefore, instead of using polyvinyl chloride sheets, we are considering attaching two polypropylene sheets to an aluminum sash frame and filling the space between the aluminum sash frame and the sheets with polyurethane foam to provide rigidity as a door. There is. Furthermore, with the transition from metal to resin for interior materials such as automobile door trims, filling polyurethane foam by injection method is being considered for the purpose of cushioning or heat insulation. As described above, there is a demand for composites of resin materials and foamed polyurethane in resin products with various complex shapes. [Problems to be solved by the invention] However, resin materials are usually used as sheets or made into molded products by thermoforming or injection molding, and when polyolefin resin in such a shape is used, foaming Due to insufficient adhesion with polyurethane, voids are formed, which has the disadvantage that the purpose of rigidity and heat insulation cannot be fully achieved. In order to improve the adhesive strength between this resin material and foamed polyurethane, it is possible to apply liquid adhesive or adhesive liquid or treat the surface with chemicals (Japanese Patent Application Laid-Open No. 60-97841).
However, the addition of complicated steps due to an increase in the number of coating steps and surface treatment steps is not preferable. The present invention eliminates such a treatment step and improves the adhesive force with urethane foam by blending an ethylene/acrylic acid random copolymer or the like into an olefin resin that adheres to urethane foam. (Structure of the Invention) The present invention provides a composite molded article having a structure in which a resin molded article having the following composition and a urethane foam are integrally laminated. Resin composition (A) Olefin resin 65-95% by weight (B) Ethylene/acrylic acid random copolymer
35 to 5% by weight The olefin resin of component (A) is a homopolymer of propylene, which has propylene as the main component, and a random combination of this and olefins such as ethylene, butene-1, hexene, 4-methylpentene-1, etc. Polypropylene such as copolymer or block copolymer, maleic anhydride grafted polypropylene; polyethylene such as high density polyethylene, low density polyethylene, linear polyethylene, ethylene/vinyl acetate copolymer, etc. can be used alone or Can be used as a mixture. In particular, the use of a propylene/ethylene block copolymer with an ethylene content of 2 to 12% by weight or a mixture of 50 to 90% by weight of polypropylene and 50 to 10% by weight of polyethylene provides good deep drawability during vacuum forming. It is preferable because it has a high adhesiveness between the resin molded product and the urethane foam. Component (B), ethylene/acrylic acid radham copolymer, was measured at 190°C according to JISK-6760.
The resin has an MFR of 30-400 g/10 min, which contains 70-99 wt% ethylene and 30-1 wt% acrylic acid.
It is a relatively low molecular weight resin obtained by random copolymerization of This product is sold by Mitsubishi Yuka Co., Ltd. under the name "Yukalon EAAA500W" (product name). If the concentration of the ethylene/acrylic acid random copolymer (B) component in the resin composition is less than 5% by weight, the adhesion between the urethane foam and the resin molded article will be low, making it impractical. On the other hand, if the amount exceeds 35% by weight, the mold releasability will be poor when a sheet made of the resin composition is vacuum formed, press formed, air pressure formed, or the resin composition is injection molded. In order to improve such mold releasability, a styrene resin may be added in an amount of 25% by weight or less, preferably 5 to 10% by weight, if necessary. As such styrene resin, polystyrene, styrene-butadiene-styrene block copolymer (SBS), styrene-acrylonitrile copolymer (SA), ABS, high impact polystyrene (HIPS), etc. can be used. Among these, ABS has higher adhesion to urethane foam. However, the olefin resin of component (A) in the resin alone does not have adhesive properties with the urethane foam. A resin composition having this composition is melt-kneaded using an extruder, extruded into a sheet or parison, and then vacuum-formed, compression-molded, or blow-molded to be used as a refrigerator lining material or a skin material for surfboards. used. Molded products such as bumpers are obtained by injection molding a resin composition into a mold. The surfaces of these molded products may be subjected to corona discharge treatment or plasma treatment, if necessary. (Composite molded product) The composite molded product is obtained by bonding the resin molded product and urethane foam together. A surf-in board is manufactured by injecting a foaming urethane liquid into the hollow part of the blow-molded product and causing the foam to form. When used as an interior material for a refrigerator, as shown in FIG. 1, a foamable urethane solution 4 is injected into a cavity 3 formed by a mold 1 made of a decorative steel plate and the vacuum-formed product 2, and then By foaming and curing, a composite molded body in which the mold 1, the urethane foam 4', and the lining material 2 are integrated is manufactured. Hereinafter, the present invention will be explained in more detail with reference to Examples. Note that parts and percentages in the examples are based on weight. Example of sheet production 1 90% by weight of crystalline propylene-ethylene block copolymer with 5% by weight of ethylene, 0.5g/10 min MFR, 98% by weight of boiling heptane extraction residue, and ethylene manufactured by Mitsubishi Yuka Co., Ltd.・Acrylic acid (20wt%) random copolymer “500W” (product name, MFR300g/10
10% by weight) was kneaded using an extruder, extruded into strands, and cut into pellets. The above resin pellets were processed using an extruder with a diameter of 90 mm.
It was fed to a flat die with a width of 700 mm at 230°C. The molten sheet extruded from the die has a width of 700 mm.
The mixture was sequentially cooled and solidified using three rolls, and then subjected to corona discharge treatment to obtain a sheet for vacuum forming. The temperature of the rolls varies from the roll closest to the die to 40℃, 95℃, and 50℃.
℃, and the rotational speed of the roll was 1.5 m/min. The total sheet thickness was 1.6 mm. Examples 2 to 7 Sheets were obtained in the same manner as in Example 1, except that the composition of the resin was changed as shown in Table 1. The abbreviations in the table are as follows. PP: Propylene/ethylene block copolymer. E・AA: Ethylene/acrylic acid random copolymer A500W: Ethylene/acrylic acid copolymer manufactured by Mitsubishi Yuka Co., Ltd. (acrylic acid content 20% by weight, MFR300)
g/10 minutes) A221M: Ethylene/acrylic acid copolymer manufactured by Mitsubishi Yuka Co., Ltd. (acrylic acid content 8.5% by weight, MFR7
g/10 minutes) PS: Polystyrene "Dialex HT516" (trade name) manufactured by Mitsubishi Monsanto Chemical Co., Ltd. SBS: SBS "Tuffrene A" (trade name) manufactured by Asahi Kasei Corporation Example 1 The sheet obtained in Example 1 above was Using a vacuum/pressure forming machine, the material was introduced into a heating furnace set at approximately 230°C, and plug-assisted molding was performed using both compressed air (5.0 Kg/cm ³ ) and reduced pressure (-600 mmHg) (drawing ratio H/D = 1). /1).
The release properties of the sheet were good, and the plug was easily separated from the sheet. After drilling an injection port in a part of this shaped sheet, this sheet is inserted into a stainless steel frame that is the frame of the refrigerator body, and then the space (cavity) formed by the frame and the shaped sheet is inserted. When a two-component foaming urethane solution "HM-1510" (trade name) manufactured by Polyurethane Kagaku Kasei Co., Ltd. was injected into the space from the injection port, foaming started after 10 seconds, and after 1 minute, the space was filled with urethane. Completely filled with foam.The density of this urethane foam is 0.05g/cm ³
It was hot. The same operation was repeated 20 times to obtain 20 composite molded body samples. After 24 hours, the sheet to which the urethane foam had been adhered was cut out, and the adhesion between the urethane foam and the sheet was measured using the following method. After separating the urethane foam from the sample piece by hand, use a knife to cut 100 1 mm squares into the sheet containing the remaining urethane foam, then stick adhesive tape on the squares, and forcefully pull the adhesive tape from the sheet. When the sheet was removed, the squares of urethane foam remaining on the sheet side were examined. The results are shown in Table 1. The evaluation criteria for adhesion are as follows. ○: Cohesive failure of urethane foam Adhesive area of squares: 81/100 to 100/100 △: Cohesive failure of urethane foam and interfacial peeling between the resin molded product and urethane occur simultaneously. Digit: 50/100 to 80/100 ×: The adhesion between the urethane foam and the resin molded product is weak, and the sheet is easily peeled off from the interface with the urethane foam. Square size: 0/100 to 49/100 Examples 2 to 4, Comparative Examples 1 to 3 Composite molded bodies were obtained in the same manner except that the resin sheets of Example 1 were replaced with those of Examples 2 to 7. Table 1 shows the adhesion between the urethane foam and the sheet of these composite molded bodies.

【table】

[Table] * Injection molded product Example 5 A mixture of 80% by weight of the propylene/ethylene block copolymer used in Example 1 and 20% by weight of the ethylene/acrylic acid random copolymer "500W" was used as a resin product, and a parison was made. The product was extruded into a shape, and then hollow-molded to obtain a hollow-molded body for a surf-in board. A two-component urethane solution was injected into the hollow part of this molded body and foamed to obtain a surf inboard. The adhesion between the urethane foam and the resin hollow body was stronger than that of Example 2. Example 6 Crystalline propylene-ethylene block copolymer 80 with ethylene content of 10% by weight and MFR of 1.2 g/10 min
A mixture of 20% by weight of the ethylene/acrylic acid random copolymer "A500W" used in Example 1 was used as a resin composition, a Mitsubishi Natco injection molding machine (800 tons) was used, and the resin temperature was 230°C. injection pressure
Injection molding was carried out at 1000 Kg/cm ² at a mold temperature of 40° C. to obtain a molded article for a passenger car bumper. This molded product was assembled into a foam frame, and a foamable two-component urethane resin was injected and foamed to obtain a bumper for a passenger car. Table 1 shows the adhesion of this molded article to the urethane foam.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing one embodiment of the present invention. In the figure, 1 is a stainless steel frame, 2 is a resin molded product (lining material), 3 is a cavity, 4' is a urethane foam, and 5 is an injection port.

Claims (1)

[Claims] 1. A composite molded product having a structure in which urethane foam and a resin molded product having the composition shown below are laminated together. Resin composition (A) Olefin resin 65-95% by weight (B) Ethylene/acrylic acid random copolymer with MFR of 30-400g/10 minutes 35-5% by weight 2 Olefin resin has an ethylene content of 2-12% by weight % propylene/ethylene block copolymer. 3 Olefin resin is polypropylene 50-90
The composite molded article according to claim 1, which is a mixture of 50% to 10% by weight of polyethylene and polyethylene.