JPH02102034A - Interior molding form for vehicle - Google Patents

Abstract

PURPOSE:To eliminate the collapse of a foamed material, generation of an uneven part on the surface of a skin material by forming small bubbles having specific size or below on the surface layer of the foamed material integrally molded with thermoplastic resin for an aggregate. CONSTITUTION:Polypropylene resin foamed material to be used is so adjusted as to contain 35% or more of gel fraction and 200mum or below of mean bubble diameter in a surface layer having at least 1mm depth from the surface of the foamed material integrally molded with an aggregate. Composite materials 3 in which a skin material 2 adheres to the foamed material 1 are disposed at predetermined positions of a pair of upper and lower molding dies 4 and 5, and suitable amount of melted thermoplastic resin 6 for the aggregate is supplied to the molding face at the side of the material 1. It is pressure molded under a predetermined temperature condition by the dies 4 and 5 to obtain a molded form 7 having no uneven part on the surface integrally molded with the aggregate 6 at the material 1 of the composite material 3.

Description

Detailed Description of the Invention [Industrial Field of Application] The present invention relates to interior molded products for vehicles such as automobiles, and in particular, the present invention relates to molded interior parts for vehicles such as automobiles, and in particular, it is possible to apply heat in a molten state to a composite body in which a skin material is bonded to a polypropylene resin foam. This invention relates to a molded product integrally molded using a plastic resin as an aggregate.

[Prior Art] Conventionally, this type of vehicle interior molded product is made by forming a composite material in which a skin material such as cloth or a soft vinyl chloride sheet is attached to the surface of a polypropylene resin foam. is placed in a mold, and under appropriate heating and pressurizing conditions, a molten thermoplastic resin serving as aggregate is supplied to the foam side of the composite, and the composite and aggregate are integrally molded. It is obtained by

[Problems to be Solved by the Invention] However, the following problems are pointed out in conventional vehicle interior molded products.

In other words, when molten resin for aggregate is supplied to the foam side of a composite material and molded, the temperature and pressure of the molten resin crushes the foam, making it thin and uneven in thickness. There were problems in that the thickness varied and became thinner) and unevenness was likely to occur on the surface of the skin material.

The present invention solves these problems, and
Vehicle interior molded products that do not crush the foam or create irregularities on the surface of the skin material when aggregate is integrally molded using molten thermoplastic resin on the foam material that has been bonded to the skin material. is intended to provide.

[Means for Solving the Problems] The present invention employs the following means to solve the above problems.

That is, the vehicle interior molded product according to the present invention comprises a polypropylene resin foam having a gel fraction of 35% or more and an average cell diameter of 200 μm or less in the surface layer portion from at least one surface to a depth of 1 mm, and a skin material. It is characterized in that a molten thermoplastic resin is integrally molded onto the surface of the surface layer of the bonded composite as an aggregate.

In the present invention, the polypropylene resin foam has a gel fraction of 35% or more and an average cell diameter of 200 μm or less in the surface layer at least 1 mm deep from the surface of the foam where the aggregate is integrally molded. .

The polypropylene resin constituting the foam includes propylene homopolymer, ethylene, α-1 such as butene-1, etc.
A polypropylene resin containing 1 to 30% by weight of olefin and copolymerized in random, random-block or block form is preferred.

Other resins may be mixed with these resins as long as they do not adversely affect the foam. For example, low-density, medium-density or high-density polyethylene, a polyethylene copolymer copolymerized with an α-olefin, or a copolymer containing ethylene with vinyl acetate or acrylic acid ester as a main component may be mixed.

A blowing agent is a compound that is liquid or solid at room temperature, decomposes or vaporizes when heated above the melting point of the polypropylene resin, and does not substantially interfere with sheet formation or crosslinking reactions. Therefore, it is preferable that the decomposition temperature is 180 to 240'C. Examples of such thermal decomposition foaming agents include azodicarbonamide, azodicarboxylic acid metal salts, dinitrosopentamethylenetetramine, and the like. These blowing agents are
It is used in a range of 0.1 to 40% by weight based on the polypropylene resin, and the mixing amount can be arbitrarily changed depending on the type and apparent density of each.

Further, as a crosslinking method, a known radiation crosslinking method or a chemical crosslinking method using an organic peroxide can be applied. Polyfunctional monomers such as divinylbenzene, diallyl phthalate, etc. can also be added to promote this crosslinking.

The polypropylene resin and the blowing agent, crosslinking accelerator, etc. may be mixed by, for example, a Henschel mixer, a Panbury mixer, a mixing roll, or a kneading extruder. Particularly when the resin is in powder form, powder mixing using a Henschel mixer is convenient. Powder mixing is usually carried out between room temperature and the softening temperature of the resin, and melt mixing is usually carried out between the melting temperature of the resin and 195°C. When producing a continuous sheet-like foam, it is desirable to form the foam into a sheet by extrusion at a temperature below the decomposition temperature of the blowing agent.

The gel fraction of the polypropylene resin foam used in the present invention is 35% or more, preferably 45 to 60%. If the gel fraction is less than 35%, the foam will be crushed by the temperature and pressure during integral molding of the aggregate, resulting in thin and uneven thickness.

Note that the gel fraction of the polypropylene resin foam is measured as follows.

First, cut the foam into approximately 1 mm squares, collect approximately 0.1 g, and accurately weigh this as a sample to determine its weight A (g
).

This sample is heated in tetralin at a temperature of 130''C for 3 hours, cooled, washed with acetone and then water to remove the eluted bone, and then dried.

The dried sample is accurately weighed and its weight is defined as B (g).

The gel fraction (%) is calculated using the following formula.

Gel fraction (%) = (B/A) Preferably it is 150 μm or less. If the thickness is 200 μm or more, bubbles are likely to break during molding, and unevenness is likely to occur on the skin side.

The average bubble diameter is measured as follows.

After enlarging the surface layer of the foam 20 to 30 times with an electron microscope and photographing the cross section of the bubbles in the longitudinal direction, where the bubble diameter is the largest, the number N of bubbles existing within a certain length range is counted. Constant length L/number of bubbles N=average bubble diameter.

In order to obtain a foam having such an average cell diameter, the following method is exemplified.

(1) When the resin/foaming agent used is the same, the higher the degree of bridge chipping reactivity (expressed as gel fraction), the smaller the cell diameter of the foam can be. For example, when chipping a bridge using ionizing radiation such as alpha and beta rays, gamma rays, X-rays, and ultraviolet rays, the irradiation energy distribution in the thickness direction of the foam sheet is changed to increase the irradiation energy in the surface layer. By increasing the gelation rate in that portion, the bubble diameter in that portion can be reduced.

(2) When a foamable sheet that has been given a bridge-breaking reaction is heated to foam, if the foamable sheet is rapidly heated at high temperatures, the core structure of the bubbles is formed in the surface layer of the foam for a short period of time. Since a large number of bubbles can be generated, the diameter of the bubbles in the surface layer portion can be reduced.

Note that these methods (1) and (2) can be used alone or in combination.

The skin material to be bonded to the polypropylene resin foam of the present invention may include fabrics made of natural or artificial fibers,
Known materials such as sheets made of polyvinyl chloride resin, thermoplastic elastomer sheets, leather, mixed sheets of polyvinyl chloride resin and ABS resin, etc. can be used.

Further, as the resin for aggregate of the present invention, a polyolefin thermoplastic resin is exemplified. These resins have low specific gravity and moderate strength, and are lighter than conventional fiber hardboards or ABS injection products.

If, for example, polyamide or polybutylene terephthalate resin, which has a considerably higher melting point than the polypropylene resin used in the foam, is used as the aggregate resin, the cells in the foam are likely to be destroyed by the high temperatures during molding.

Polyolefin resins used as aggregates include:
Polypropylene resin, polypropylene resin in which propylene and olefin are copolymerized in random, random block, or block form, polyethylene resin or copolymer resin of ethylene and α-olefin, copolymer resin with vinyl acetate or acrylic ester. Polymer resins and arbitrary mixtures of these resins can be used.Furthermore, inorganic compounds such as talc, silicic acid, and calcium carbonate can be mixed with these resins as fillers to the extent that they do not impair their properties as aggregate resins. Also, for aggregate resin,
Known heat stabilizers, antioxidants, nucleating agents, colorants, etc. may be added as necessary.

Further, resins other than olefin resins such as ABS resin, polystyrene resin, petroleum resin, etc. may be added as long as the moldability is not impaired.

Next, a method for molding a vehicle interior molded product according to the present invention will be described. Although the molding method is not particularly limited, the so-called Honto Sumping molding method, which can set the molding pressure lower than injection molding, is preferred in order to reduce uneven thickness of the foam and cell collapse.

FIG. 1 is an explanatory diagram showing an example of the Honto Sumping mold method.

As shown in FIG. 1(a), a composite material 3 made by bonding a skin material 2 to a polypropylene resin foam l is placed at a predetermined position in a mold 4.5 on the upper and lower sides of the foam 1. An appropriate amount of molten thermoplastic resin 6 for aggregate is supplied to the molding surface (in this example, the molding surface of the lower mold 5). And Fig. 1 (b
) As shown in FIG. 1(C), by press-forming under predetermined temperature conditions using a mold 45, a vehicle interior in which the aggregate 6 is integrally molded into the foam 1 of the composite material 3 as shown in FIG. 1(C) is produced. A molded article 7 is obtained.

The second part is an explanatory diagram showing another example of the Honto Sumping mold method.

In this example, as shown in FIG. 1(a), a pre-molded composite material 3 is placed in a predetermined position in a mold 5 with the foam 1 facing upward, and bone is placed on the foam 1. A molten thermoplastic resin 6 for material is supplied. Then, by performing pressure molding as shown in FIG. 2 et al., a vehicle interior molded product 7 as shown in FIG. 2(C) is obtained.

[Example code] The present invention will be explained in detail below.

Jitsugai Masudo-I A mixed resin system of 80% polypropylene resin copolymerized with 4% by weight of ethylene and 20% linear polyethylene resin with a melt index (Ml) of 7.0 and a density of 0.930 g/cc. 100 parts by weight, 6 parts by weight of azodicarbonamide as a blowing agent (Example 1), 15 parts by weight (Example 2), 3 parts by weight of divinylbenzene as a bridge chipping aid, and a phenolic/phosphorus stabilizer. A foamable composition mixed with 0.3 parts by weight of each was formed into a sheet with a thickness of 1.55 mm using the T-die method using an extruder, and the ratio of irradiation energy on one sheet surface to the irradiation energy on the other surface was 1.3. ,
After irradiating with ionizing radiation to obtain an average gel fraction of 50%, the material was rapidly foamed on a salt bath at 230° C. to obtain a foam. The average cell diameter in the surface layer of the obtained foam was 6.
0 to 1801 Im, a soft vinyl chloride resin sheet was attached as a skin agent to the surface of the foam with a rough average cell diameter using a polyester adhesive to prepare a composite material.

A molten polypropylene resin for aggregate with a resin temperature of 175°C was placed on the opposite side of this composite material (the side with a smaller average cell diameter), and molded into a body at a pressure of 60 kg/cm''.

As shown in the following table, the obtained molded product had no unevenness on the surface of the skin material and had little denting of the foam.

Similarly to Examples 1 and 2, sheets containing 6 parts by weight (Comparative Example 1) and 15 parts by weight (Comparative Example 2) of azodicarbonamide as a foaming agent were made to have a gel fraction of 30% and were subjected to a slow foaming method. A foam was made and a molded article was made under the same construction conditions as in the example.

As shown in the following table, unevenness occurred on the surface of the skin material of this molded product, and the foam was destroyed during molding.

The evaluation results of Examples 1 and 2 and Comparative Examples 1 and 2 described above are shown in the following table.

In the table above, each evaluation symbol for surface unevenness is as follows: ◎: There is no unevenness on the surface of the skin material O: The unevenness on the surface of the skin material is mild and does not pose a problem for practical use Unsuitable XX: Indicates that the surface of the skin material has significant irregularities and has no practical value as a molded product.

Further, the heckle rate of the foam was determined by the following formula.

Settling rate = ((Thickness of foam before integral molding - Thickness after molding) / Thickness of foam before integral molding lX100 [Effects of the Invention] As is clear from the above description, according to the present invention, bone Because small cells with an average cell diameter of 200 μm or less are formed on the surface layer of the foam that is integrally molded with the thermoplastic resin for the material, the foam will not be crushed by the pressure when integrally molding the aggregate. A high-quality vehicle interior molded product can be obtained without causing unevenness on the surface.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram of an example of the method for molding a vehicle interior molded product according to the present invention, and FIG. 2 is an explanatory diagram of another example of the method for molding a vehicle interior molded product according to the present invention. 1... Polypropylene resin foam 2... Skin material 3... Composite material 4... Upper mold 5... Lower mold 6... Thermoplastic resin for aggregate 7... Vehicle interior Article applicant Toshi Co., Ltd. Company agent Tsutomu Sugitani, patent attorney Figure 1 (a) Figure 2 (a) Figure 1 (b) Figure 2 (b) Figure 1 (C) Figure 2 (C)

Claims (1)

[Claims] (1) Gel fraction is 35% or more, and the average bubble diameter in the surface layer from at least one surface to a depth of 1 mm is 200 μm
A vehicle interior molded product made by integrally molding a molten thermoplastic resin as an aggregate on the surface layer portion of a composite body made by bonding a skin material to the following polypropylene resin foam.