JPH05254047A - Molded interior product for vehicle - Google Patents

Abstract

PURPOSE:To provide a molded interior product almost uniform in elongation in its thickness direction and prevented from trouble such as the destruction of foam at the time of molding due to a stamping molding method by using polypropylene foam whose elongations at three stages of temps. are adjusted so as to enter the specific range of the average vlue of the elongation values. CONSTITUTION:A skin material is laminated to one surface of polyolefinic foam and a thermoplastic resin for aggregate is integrally molded on the other surface thereof by a stamping molding method. Herein, the polyolefinic foam is adjusted so that the elongations (a), (b), (c) thereof at 50, 120, 160 deg.C are enter the range of + or -30% of the average value of the elongation values. Further, polypropylene type foam composed of a propylene homopolymer or a propylene/ other olefin or vinyl acetate copolymer having apparent densit 0.10g/cm<2> or less and a gel ratio of 40% or more is used.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vehicle interior in which a skin material is laminated on one surface of a polyolefin foam and a thermoplastic resin for aggregate is integrally molded on the other surface by a stamping molding method. Regarding molded products.

[0002]

2. Description of the Related Art The stamping mold method is a method in which a molten thermoplastic resin for an aggregate is distributed and supplied in the form of a large number of balls or sheets on one press surface of a die, and then,
A composite material consisting of an upper skin material and a lower polypropylene resin foam is supplied in a heated state, and by pressurizing both in that state, the thermoplastic resin for aggregate is integrated into the composite material by heat fusion. It is a method of molding.

Conventionally, as a vehicle interior molded product molded by a stamping molding method, a foaming ratio of the front and back of the polyolefin foam is set to a predetermined value in order to prevent thermal destruction of the polyolefin foam during stamping molding. The one in which the expansion ratio is controlled so as to give a difference in the range (see Japanese Patent Application Laid-Open No. 1-222937), and the one in which the average cell diameter of the surface layer portion of the foam is controlled to a predetermined value or less (see Japanese Patent Application Laid-Open No. 2-102034). ) Have been proposed respectively.

[0004]

However, since such a foam of the prior art always has a front side and a back side having different foaming properties, it is difficult to handle the foam in the step of bonding the foam and the skin material and the like. It becomes troublesome and the workability is poor.

Further, in the former case, as a method for making a difference in the expansion ratio between the front and back of the foam, a method of providing a difference in the heating temperature and the crosslinking reactivity at the time of foaming on both sides is mentioned. When the foaming is carried out, the foaming speeds on both sides also differ, causing a phenomenon generally called curl, which makes it impossible to stably produce the foam, resulting in an increase in the cost of the foam.

An object of the present invention is to provide an interior molded article for a vehicle that overcomes the above problems.

[0007]

An interior molded article for a vehicle according to the present invention has been devised to achieve the above object.
In a molded product in which a skin material is attached to one surface of a polyolefin-based foam and a thermoplastic resin for aggregate is integrally molded to the other surface by a stamping molding method, the polyolefin foam has an elongation at 50 ° C. Rate a%, elongation at 120 ° C b%, 160 ° C
When the elongation rate in c is assumed to be c%, the respective elongation rates a, b and c are adjusted to be within ± 30% of the average value of these values, and the apparent density is 0.10 g / cm ³ or less. A polypropylene-based foam having a fraction of 40% or more is used.

In the present invention, the reason why the elongation percentages a, b and c at 50 ° C., 120 ° C. and 160 ° C. are adjusted to be within ± 30% of the average value of these values as the polyolefin foam is This is because, for example, the elongation percentage b at 120 ° C. may be greater than the elongation percentages a and c at 50 ° C. and 160 ° C., so it is necessary to make the elongation percentages at the above temperatures uniform. It is particularly preferable that the respective elongations a, b and c fall within ± 20% of the average value of these values. In order to adjust the respective elongations a, b and c so as to fall within the above ranges, the above-mentioned bifunctional monomer and trifunctional monomer may be used as the crosslinking assistants described below.
A mixture of 0: 1.0 to 2.0, preferably 1.0: about 1.5 is used.

The reason why the apparent density of the foam is limited to 0.10 g / cm ³ or less is that when the density exceeds 0.10 g / cm ³ , the molded product obtained by the stamping molding method feels stiff and stiff. This is because it loses the texture required for vehicle interior materials. A particularly preferable apparent density is 0.08 g / cm ³ or less.

The reason why the gel fraction of the foam is limited to 40% or more is that when the gel fraction is less than 45%, the heat resistance of the foam is insufficient, and the molding heat and molding pressure during stamping molding are insufficient. This is because the bubbles are destroyed by this, unevenness occurs on the surface of the molded product, and the uniformity of elongation is lost. A particularly preferred gel fraction is 50-60%.

As the polypropylene resin foam, those obtained by various methods as described below can be applied.

A) A polypropylene resin is mixed with a foaming agent, and the resin is extruded into a sheet shape by an extruder to produce a non-crosslinked polypropylene foam sheet, or a foaming agent is injected into the extruder. Meanwhile, the same resin is extruded into a sheet shape to produce a non-crosslinked polypropylene foam sheet.

B) A polypropylene resin is mixed with a foaming agent, a crosslinking aid, etc., and the resin is formed into a sheet by an extruder or a calender roll to produce a foamable sheet, and the sheet is heated to crosslink. And foaming at the same time to produce a cross-linked polypropylene-based foamed sheet, or by mixing a polypropylene-based resin with a foaming agent or a cross-linking auxiliary agent, making it into a sheet shape with an extruder or a calender roll, and then electronically applying this sheet. After cross-linking by irradiating radiation such as rays, the cross-linked polypropylene-based foamed sheet is manufactured by heating and foaming (so-called pre-cross-linking).

Of these methods, the pre-crosslinking method is particularly preferable.

The polypropylene resin is not particularly limited as long as it is based on polypropylene. Homopolymers of propylene, copolymers of propylene and other olefins, vinyl acetate, acrylic acid, acrylic acid ester, etc., It may be a block resin, a random block, or a random copolymer of a polypropylene resin with another olefin resin. If polypropylene alone lacks flexibility, blend 5 to 50 parts by weight, preferably 30 to 40 parts by weight of low density polyethylene, linear low density polyethylene, high density polyethylene, ethylene vinyl acetate copolymer according to required quality. You may.

The cross-linking method of the resin molded product includes electron beam and α
There are a method of using ionizing radiation such as rays, β rays, γ rays, X rays and ultraviolet rays, and a method of heating a resin composition containing an organic peroxide. In the former case, the irradiation dose is usually 1 to
It is 50.0 Mrad.

As the crosslinking assistant, difunctional monomers such as divinylbenzene, divinylnaphthalene, 1,9-nonanediol dimethacrylate and diallyl phthalate, and trifunctional monomers such as trimethylolpropane trimethacrylate and triallyl trimellitate are used. Be done. Bifunctional monomer and trifunctional monomer 1.0: 1.0-
A mixture of 2.0, preferably 1.0: about 1.5 is used. The preferable addition amount of the crosslinking aid is resin 10
It is 1.0 to 4.0 parts by weight with respect to 0 parts by weight.

As the foaming agent, azodicarbonamide,
An organic decomposition type foaming agent such as dinitrosopentamethylenetetramine, allophanic acid amide, p, p′-oxybisbenzenesulfonyl hydrazide, or an inorganic decomposition type foaming agent such as sodium bicarbonate can be appropriately used. Among these, azodicarbonamide or the one based on it is preferable. In order to accelerate the decomposition of the foaming agent, a known decomposition aid such as zinc oxide or zinc stearate may be appropriately added. The preferred addition amount of the foaming agent is 5 to 20 parts by weight with respect to 100 parts by weight of the resin.

As a heating means for foaming, hot air, a heater, or a combination thereof is used.

Antioxidants, heat stabilizers, metal damage inhibitors, inorganic fillers, UV absorbers, pigments, petroleum resins and the like can be added to the polypropylene resin composition as required.

In the method for producing a polypropylene resin foam by pre-crosslinking, a blowing agent, a crosslinking aid, etc. are added to the polypropylene resin, and if necessary, an inorganic filler, a coupling agent and various additives are added. The obtained compound is melt-kneaded to form a foamable polypropylene resin composition, the composition is molded into a desired shape such as a sheet, and the molded product obtained is crosslinked by irradiation with ionizing radiation, and then heated. By decomposing the foaming agent, foaming is performed to form a foam. The above molding is performed as follows. Using a general-purpose kneading device such as a single-screw extruder, a twin-screw extruder, a Banbury mixer, a kneader mixer, or a roll, the compound is melt-kneaded at a temperature lower than the decomposition temperature of the thermal decomposition type foaming agent, and the resulting kneading is performed. Items are usually formed into sheets.

As the skin material, a soft polyvinyl chloride sheet, a polyvinyl chloride sheet containing an ABS resin, a thermoplastic elastomer sheet, synthetic leather, or a cloth-like material using natural fibers or synthetic fibers is used.

On the other hand, it is preferable to use polypropylene resin as the thermoplastic resin for the aggregate, but other polyolefin resins, ABS resin, polystyrene resin and the like are also applicable.

[0024]

When a skin material is attached to one surface of a polyolefin-based foam and a thermoplastic resin for aggregate is integrally molded on the other surface by a stamping molding method, about 200 is applied to one surface of the foam at room temperature. Since the thermoplastic resin for aggregate, which is molten at a temperature as high as ℃, touches, a temperature gradient can be formed in the thickness direction of the foam. Therefore, if the elongation at break of the foam is non-uniform depending on the temperature, the foam breaks from a portion at a temperature at which the foam has poor elongation, which causes a problem in molding by the stamping molding method.

In the present invention, 50 ° C., 120 ° C. and 1
Since the polypropylene-based foam adjusted so that the respective elongations a, b, and c at 60 ° C. are within ± 30% of the average value of these values, a substantially uniform elongation in the thickness direction is obtained, There is no risk that the foam will break and cause other problems during molding by the stamping molding method.

[0026]

EXAMPLES Next, examples of the present invention will be described.

Example 1 Polypropylene (melt flow rate = 2.0, density =
0.900) 60 parts by weight and linear low-density polyethylene (melt index = 20, density = 0.920) 40
7 parts by weight of azodicarbonamide as a foaming agent and 1.0 part by weight of trimethylolpropane trimethacrylate and 1.5 parts by weight of 1,9-nonanediol dimethacrylate as a cross-linking agent were added to a resin blend with 1 part by weight. Then, the obtained blend was melt-kneaded by a twin-screw extruder (120φ), and the kneaded product was extruded at a temperature not higher than the decomposition temperature of azodicarbonamide to form a sheet having a thickness of 1.5 mm.

Then, the sheet was irradiated with an electron beam of 6.0 Mrad to be crosslinked, and then heated in a hot air vertical type foaming furnace.
It was foamed by heating at 0 ° C.

Thus, the expansion ratio is 15 times and the thickness is 3.0 m.
m, apparent density 0.067 g / cm ³ , gel fraction 49.8
% Foamed sheet was obtained.

Next, one side of this foamed sheet was subjected to corona treatment, and a urethane adhesive was used on the treated side to make ABS.
A skin material made of a resin-containing polyvinyl chloride sheet (0.6 mm) was bonded to form a composite material made of a foamed sheet and the skin material.

Finally, polypropylene resin as a thermoplastic resin for aggregate is melted at a temperature of about 200.degree.
It is extruded onto one pressing surface of the stamping mold by the die method, the above composite material is placed on the same resin so that the foamed sheet surface is in contact, and the temperature is 60 ° C. and the pressure is 9 by pressing.
A pressure was applied at 0 kg / cm ² , and the above resin was heat-bonded integrally to the composite material to obtain a vehicle interior molded product.

Example 2 Polypropylene (melt flow rate = 0.5, density =
0.900) 60 parts by weight and linear low density polyethylene (melt index = 8, density = 0.920) 40 parts by weight were used as the resin blend, and otherwise the same operation as in Example 1 was performed. As a result, a molded vehicle interior product was obtained. The gel fraction of the foam in this example was 42.2%.

Comparative Example 1 A vehicle interior molded article was obtained by setting the electron beam irradiation dose to 4.0 Mrad and otherwise performing the same operation as in Example 1.

Comparative Example 2 The amount of the blowing agent azodicarbonamide added was 4 parts by weight,
Otherwise, the same operations as in Example 2 were carried out to obtain a vehicle interior molded product. The apparent density of the foam in this example is 0.
It was 103 g / cm ³ .

Physical Properties Test In obtaining the interior molded articles for vehicles of Examples and Comparative Examples, the presence or absence of breakage of the foam during stamping molding, the texture of the obtained molded articles, and the presence or absence of irregularities on the surface of the molded articles were examined. .. The results are shown in Table 1.

[0036]

[Table 1] As is clear from the above table, the molded articles of the examples showed good results in any of the items whether or not the foam broke, the texture of the resulting molded article, and the presence or absence of irregularities on the surface of the molded article. ..

[0037]

Industrial Applicability According to the present invention, there is provided a polypropylene foam which is adjusted so that the respective elongations a, b and c at 50 ° C., 120 ° C. and 160 ° C. are within ± 30% of the average value of these values. Since it is used, almost uniform elongation can be obtained in the thickness direction, and there is no fear that the foam will be broken during molding by the stamping molding method and other problems will occur.

Therefore, it is possible to manufacture a high-quality interior molded article for a vehicle having a good appearance without surface irregularities with a high yield.

Further, since there is no difference between the front and the back of the foam, the foam is easy to handle in the step of bonding the foam and the skin material, and the workability is very good.

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Claims (1)

[Claims] 1. A molded product in which a skin material is attached to one surface of a polyolefin foam and a thermoplastic resin for an aggregate is integrally molded to the other surface by a stamping molding method. When the elongation at 50 ° C is a%, the elongation at 120 ° C is b%, and the elongation at 160 ° C is c%, the respective elongations a, b and c are ± 30 of the average value of these values.
% So that the apparent density is 0.10g
An interior molded article for a vehicle, which is characterized by using a polypropylene-based foam having a gel fraction of 40% or more / cm ³ or less.