JP3006378B2 - Vehicle interior molded product and method of manufacturing the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vehicular interior molded product, and more particularly to a vehicular interior molded product using a polyolefin resin foam.

[0002]

2. Description of the Related Art Japanese Patent Application Laid-Open No. 1-222937 discloses a vehicle interior which can improve quality and productivity without using an adhesive at the time of integral molding and eliminating the need for pre-molding a composite material to an aggregate. Moldings are shown. The interior molded product for a vehicle has a gel fraction of 35% or more, and a difference in average foaming ratio of a thickness portion of 0.5 mm from both surfaces of the both surfaces is 2 to 2.
Polyolefin-based resin foam of 20 times, a skin material bonded to the surface of the foam having a higher average magnification, and a molded body integrally formed by hot stamping molding on the surface of the foam having a lower average magnification. Aggregate made of a thermoplastic resin. And when performing the foaming treatment on the unfoamed sheet, by lowering the heating temperature on the other surface than the heating temperature on one surface,
There is a difference in the expansion ratio between both sides of the foam.

[0003]

In the above-mentioned conventional vehicle interior parts, an adhesive is not used at the time of integral molding, and a prior molding of a composite material to an aggregate is not required, thereby improving quality and productivity. Although it is possible, there is a problem that the feel (soft feeling) at the time of use is insufficient. SUMMARY OF THE INVENTION It is an object of the present invention to eliminate the use of an adhesive at the time of integral molding, to eliminate the need for the composite material to be molded in advance, and to improve the feel during use.

[0004] A vehicle interior molded product according to the present invention is a crosslinked polyolefin resin foam having a difference in average expansion ratio of 1.1 to 10.0 times in a thickness portion from the surface on both sides to 0.2 mm, A skin material bonded to the surface of the foam having a large average magnification and an aggregate made of a thermoplastic resin integrally molded by a hot stamping mold method on the surface of the foam having a small average magnification are provided. I have. And foaming
The body is provided with a difference in average expansion ratio by compression after heating. Also, for a vehicle according to the present invention.
The manufacturing method of the interior molded product includes the following steps. ◎ A step of heating the crosslinked polyolefin resin foam. ◎ Compress the heated foam, from both surfaces of the foam
The difference of the average expansion ratio of the thickness portion up to 0.2 mm is 1.1
A step of up to 10.0 times. ◎ A skin material is stuck on the side of the foam with the higher average magnification.
Process to make it. ◎ Hot stamping on the side of the foam with the smaller average magnification
Aggregate made of thermoplastic resin is integrated by gmold method
Forming process.

******** Polyolefin-based resin foam The material of the polyolefin-based resin foam is from 0.5 to
It is preferred to use a polypropylene resin in which 35% of ethylene is copolymerized in random, block or random-block form. The density is 0.897 to 0.95
A polyethylene resin having an MI of 0.5 to 50 at 5 g / cm ³ ;
Polyethylene resin copolymerized with ethylene and α-olefin; polyethylene resin copolymerized with ethylene and monomers such as vinyl acetate, acrylic acid, acrylate ester; or polyethylene resin copolymerized with the above-mentioned polypropylene resin or polyethylene resin Can also be used as a foam material.

[0006] Other resins may be further mixed with the above resin within a range that does not adversely affect the foam. For example, low-, medium-, or high-density polyethylene, a polyethylene-based copolymer obtained by copolymerizing an α-olefin, or a copolymer with ethylene-based vinyl acetate or acrylate may be mixed. The gel fraction of the polyolefin-based resin foam used in the present invention is 20% or more, and preferably 46% or more from the viewpoint of suppressing the melt fracture of cells. If the gel fraction is less than 20%, bubble destruction occurs due to heat and pressure during molding, and irregularities occur on the skin material side.

[0007] The gel fraction refers to a value measured as follows. First, a foam is cut into a square of about 1 mm, a sample of about 0.1 g is collected, and this is precisely weighed to obtain a weight A (g). This sample is heated in tetralin at 130 ° C. for 3 hours, washed with acetone after cooling, further washed with water to remove eluted components, and finally dried. The dried sample is precisely weighed and its weight is defined as B (g). The gel fraction (%) is calculated by the following equation.

Gel fraction (%) = B / A × 100 The difference in average expansion ratio between the surface and the thickness of 0.2 mm from the surface of each of the polyolefin resin foams is 1.1 to 10.0 times. (Preferably 5 to 15 times). If this is less than 1.1 times, irregularities occur on the skin material side. On the other hand, if it exceeds 10 times, the product will be warped or deformed due to the difference in the degree of shrinkage due to cooling after molding. An average expansion ratio of 5 to 35 times is suitably used.

As a method for producing a polyolefin resin foam used in the present invention, any method may be used as long as it is a method for producing a known crosslinked polyolefin resin foam. For example, even one manufactured by a method using a pyrolysis type foaming agent, one manufactured by kneading a liquid and a polyolefin-based resin in an extruder, and manufacturing it by a method called extrusion foaming in which the liquid is gasified. Good. As a particularly preferred method, a polyolefin-based resin, a foaming agent, a method of crosslinking a mixture comprising a crosslinking accelerator with ionizing radiation, and then heating the mixture to a temperature equal to or higher than the decomposition temperature of the foaming agent to cause foaming, a polyolefin-based resin, a foaming agent, A method of heating a mixture composed of an organic peroxide and a crosslinking accelerator (a crosslinking regulator if necessary) to a temperature equal to or higher than the decomposition temperature of the organic peroxide and the foaming agent to perform crosslinking and foaming. These methods are suitable for producing an endless continuous sheet foam.

A blowing agent is a compound that is liquid or solid at room temperature and that decomposes or vaporizes when heated to a temperature higher than the melting point of the polyolefin resin, and does not substantially hinder sheeting or crosslinking reaction. Can be used, but those having a decomposition temperature in the range of 180 to 240 ° C are preferable. Specific examples thereof include azodicarbonamide, azodicarboxylic acid metal salt, and dinitrosopentamethylenetetramine. These foaming agents are used in the range of 0.1 to 40% by weight based on the polyolefin resin, and the mixing amount can be arbitrarily changed depending on the type and foaming ratio.

When an organic peroxide is used in the crosslinking reaction,
It is preferable that the decomposition temperature is not lower than about 120 ° C. (particularly not lower than 150 ° C.) when the decomposition temperature is higher than the flow start temperature of the polyolefin resin used in the present invention and the decomposition half-life is 1 minute. Specific examples thereof include methyl ethyl ketone peroxide (182 ° C.), t-butyl peroxyisopropyl carbonate (153 ° C.), and dicumyl peroxide (171 ° C.). These organic peroxides are used in an amount of 0.01 to 10% by weight (preferably 0.05 to 5% by weight) based on the polyolefin resin.

Representative examples of the crosslinking accelerator include divinylbenzene, diallylbenzene, divinylnaphthalene and the like. The preferable addition amount is 0.1 to 30% by weight (more preferably 0.3 to 30% by weight) based on the polyolefin resin.
20% by weight). The mixing of the blowing agent, the crosslinking accelerator, and the organic peroxide with the polyolefin resin can be performed by a conventionally known mixing method. For example, there are mixing with a Henschel mixer, mixing with a Banbury mixer, mixing with a mixing roll, mixing with a kneading extruder, foaming agent, crosslinking accelerator, immersion of a polypropylene resin in a solution in which an organic peroxide is melted, and the like. Used with or in combination. In particular, when the resin is in a powder form, powder mixing by a Henschel mixer is convenient. Powder mixing is usually carried out between room temperature and the softening temperature of the resin. Melt mixing is usually performed in a range from the melting temperature of the resin to 185 ° C.

When producing a continuous sheet-like foam,
It is desirable to form the sheet into a sheet by extrusion at a temperature not higher than the decomposition temperature of the foam. Crosslinking and foaming of the uniformly mixed or kneaded molded foaming composition can be performed by heating under normal pressure or under pressure in a temperature range of 130 to 300 ° C, preferably 150 to 260 ° C when using an organic peroxide. it can. When the crosslinking and the decomposition of the foaming agent occur almost simultaneously at the time of heating, a method is used in which the foam is heated at the time required for crosslinking and foaming in a mold that can be pressurized and sealed, and simultaneously with the pressure reduction. This method is extremely effective when the powder mixture is foamed as it is. In the case where the blowing agent does not decompose under the heat cross-linking conditions, a method is used in which the cross-linking is performed and then heating is performed under normal pressure or under pressure at a temperature not lower than the decomposition temperature of the foaming agent. In particular, in order to obtain a foam having fine bubbles, a method of foaming under pressure is preferable. The heating time required for crosslinking and foaming varies depending on the heating temperature, the thickness of the object to be foamed, and the like, but is usually 1 to 30 minutes.

When the foamable composition is crosslinked by irradiation with ionizing radiation, the ionizing radiation includes electron beams from an electron beam accelerator, α, β, and γ rays from Co ^{60 and} other radioisotopes. Preferably, X-rays or ultraviolet rays may be used. These irradiation doses depend on the type of crosslinking accelerator,
Although it depends on the desired crosslinking ratio, it is generally 0.1%.
-30 Mrad, preferably 0.5-20 Mrad.

As a means for providing a difference in the average expansion ratio between both surfaces of the polyolefin resin foam, a pressure roll is used. For example, the polyolefin-based resin foam is heated to a surface temperature of 80 to 120 ° C. using an infrared lamp or the like, and is further supplied between cooling and compression rolls. As the cooling compression roll, a roll having a surface of 50 to 200 mesh sandblasted and a speed ratio set to 1.0: 1.3 is preferable. The clearance of the compression roll is preferably 25 to 75% of the thickness of the polyolefin resin foam, and the pressure applied by the compression roll is 1.0 to 10.0 kg / c.
m ² (preferably 3.5 kg / cm ² ).

The average flattening rate of the air bubbles in the part having a thickness of up to 0.2 mm from the surface on each side of the polyolefin resin foam thus obtained is preferably 1/5 or less, more preferably 1/10 or less. . Here, the average flatness is an average of values obtained by dividing the maximum value of the cell diameter in the thickness direction of the foam sheet by the maximum value of the cell diameter in the direction of the foam sheet for each cell. In addition, the maximum value of the cell diameter in the foam sheet direction for each cell in the thickness portion from the surface to 0.2 mm is equal to or more than 1/3 of the value averaged from 0.2 mm to the inside from the surface. And more preferably 1
/ 2 or more. Skin material / aggregate Examples of the skin material to be bonded to the polyolefin resin foam of the present invention include fabric-like sheets using natural or artificial fibers, sheets made of polyvinyl chloride resin, thermoplastic elastomer sheets, and leather sheets. Known ones can be used. The skin material is adhered to the surface of the polyolefin resin foam having a higher average expansion ratio by, for example, a two-component polyester adhesive.

As the thermoplastic resin for aggregate used in the present invention, a polypropylene resin is preferable, but the same material as the above-mentioned polyolefin resin foam material, an ABS resin, a polystyrene resin and the like can also be used. As a combination of the polyolefin resin foam and the thermoplastic resin for aggregate, a combination of a polypropylene resin foam and a polypropylene resin is preferable. Further, a combination of different materials such as a combination of a polyethylene resin foam and a polyethylene resin, or a combination of a polypropylene resin foam and a polyethylene resin may be used. However, in the case of a combination of different materials,
For example, it is preferable to perform heat fusion with an adhesive film such as an admer film (manufactured by Mitsui Oil) or Cranbetter (manufactured by Kurashiki Boseki).

The hot stamping molding method is a method in which a molten thermoplastic resin for an aggregate is dispersed and supplied in the form of a dumpling or a sheet on one press surface of a mold, and a polyolefin-based resin is placed thereon. This is a method in which a composite material in which a skin material is bonded to a resin foam is supplied in a heated state and pressurized, so that the thermoplastic resin for aggregate and the composite material are molded while being integrated by heat fusion.

Here, the surface of the polyolefin-based resin foam having a low average expansion ratio is brought into contact with the molten thermoplastic resin for aggregate, and is molded while being integrated by heat fusion. For example, polypropylene resin as a thermoplastic resin for aggregate is melted at a temperature of 210 ° C., and 300 g is extruded onto a lower mold by a T-die method. Then, a composite sheet comprising a polyolefin-based resin foam and a skin material is disposed on the resin. At this time, the foamed body is arranged such that the surface subjected to compression processing is in contact with the polypropylene resin.
In this state, 20 to 150 kg / cm ² (preferably 4
By applying a pressure of 0.8 kg / cm ² ) for 15 to 300 seconds (preferably 45 seconds), the composite sheet and the polypropylene resin are integrally molded, and the aggregate is thermally fused to the composite sheet.

[0020]

This vehicle interior molded product has a difference in the average expansion ratio between both surfaces of the polyolefin resin foam, and has a lower average expansion ratio (that is, a portion having a smaller cell).
Is brought into contact with the molten thermoplastic resin for aggregate, and is integrally molded by a hot stamping molding method. Therefore, even when heat is transferred from the thermoplastic resin for aggregate to the polyolefin-based resin foam, the bubbles at the contact surface portion where the heat is transferred are small, and even when expanded by heat, the bubbles are destroyed. It is hard to spread to other bubbles even if the bubbles are broken. As a result, it is possible to prevent the occurrence of unevenness on the surface of the skin material. In addition, since compression processing is used, the compression hardness is small, and excellent feel (soft feeling) can be obtained.

Further, since it is not necessary to mold the composite material or the aggregate in advance, the number of steps can be reduced and the productivity can be improved. Furthermore, compared to the conventional vacuum compression molding method,
Since no adhesive is used at the time of molding, the cost can be reduced and the risk of environmental deterioration and fire can be reduced.

[0022]

EXAMPLES Examples 1 to 4 80% of a polypropylene resin in which 5% by weight of ethylene was randomly copolymerized, and a melt index (MI) of 7.
0, and four types of 3.0 mm thick polypropylene-based resin foam composed of 20% of a linear polyethylene resin having a density of 0.918 g / cm ³ . Table 1 shows the density before compression processing and the 25% compression hardness of each polypropylene resin foam.
Shown in

One surface of the polypropylene resin foam is heated to 80 to 100 ° C. with an infrared lamp, and the surface is sandblasted to 100 mesh and the speed ratio is 1.0: 1.3. It was fed between chill compression rolls. The applied pressure is 3.5 kg / cm ² , and the surface temperature of the foam passed through the cooling / compression roll is 30 to 45 ° C.
Met. The thickness of the foam after compression was 2.5 mm.

A soft polyvinyl chloride sheet having a thickness of 0.4 mm as a skin material was adhered to a surface of the obtained foam that had not been subjected to compression processing using a two-component polyester-based adhesive to obtain a composite sheet. . On the other hand, a polypropylene resin as a thermoplastic resin for aggregate is melted at a temperature of 210 ° C.,
300 g was extruded onto the lower mold by the T-die method. The composite sheet was placed on the polypropylene resin.
At this time, the foam was arranged such that the compressed surface of the foam contacted the polypropylene resin. In this state, 4
A composite sheet and a polypropylene resin were integrally molded by applying a pressure of 0.8 kg / cm ² for 45 seconds. As a result, the aggregate was thermally fused to the composite sheet to obtain a molded product 1 as shown in FIG. In FIG. 1, a molded product 1
Is composed of a laminated composite material 2 and an aggregate 3. The composite material 2 is composed of a laminated foam 4 and a skin material 5.
It is composed of

Table 1 shows the evaluation of stamping moldability (surface state) and feel (softness) of the obtained molded product. Comparative Examples 1 to 4 The same polypropylene-based resin foam as in Examples 1 to 4 was used.
Kind prepared. Table 1 shows the density and compression hardness of each polypropylene resin foam.

The polypropylene resin foam was bonded to a skin material without compression. Then, the obtained composite sheet was thermally fused to the same aggregate as in Examples 1 to 4,
A molded product as shown in FIG. 1 was obtained. Table 1 shows the evaluation of the stamping moldability (surface state) and feel (softness) of the obtained molded product.

[0027]

[Table 1]

As is clear from Table 1, the compressed foam according to the present invention is 25% less than the foam of the comparative example.
Compression hardness decreases. In the embodiment of the present invention, the compression hardness is small, so that when used as an interior molded product for a vehicle, a tactile sensation (soft feeling) that satisfies the requirements of the market can be obtained. In addition, there is no unevenness due to the destruction of the skin material during stamping molding, and an excellent appearance can be obtained. Examples 5 to 8 and Comparative Examples 5 to 8 Foams having the material configuration of Examples 1 to 4 and having a thickness of 4 mm, average expansion ratios of 20 and 25 times, and an average gel fraction of 49 to 51% were prepared.

The surface having a large apparent density in the thickness region from the surface layer of the foam to 0.2 mm is heated by an infrared lamp until the surface temperature becomes 110 ° C. (heat label method).
Further, the surface was sand-blasted to 120 mesh and supplied between cooling and compression rolls having a roll speed ratio of 1.0: 1.3. The thickness of the foam after compression working at a pressure of 3.5 kg / cm ² was 3.1 to 3.5 mm.

The effect of the obtained compressed foam was evaluated according to the methods of Examples 1 to 4. In addition, the foam obtained without compression processing was evaluated as it was according to the method of Examples 1-4 for comparison.

[0031]

[Table 2]

According to the vehicle interior molded product of the present invention,
No adhesive is used at the time of integral molding, and the composite material does not need to be molded in advance. In addition, since the foam is provided with a difference in the average expansion ratio by being subjected to compression processing after heating, the feel during use is improved.
Further, according to the production method of the present invention, the composite material or the bone
Since there is no need to pre-mold the material, it can be manufactured with few processes
it can. In addition, there is no need to use adhesive when molding
Cost can be reduced and environmental degradation can be prevented.
You.

[Brief description of the drawings]

FIG. 1 is a sectional view of one embodiment of a vehicle interior molded product according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Molded product 2 Composite material 3 Aggregate 4 Polypropylene resin foam 5 Skin material

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-1-222937 (JP, A) JP-A-62-278028 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) B32B 1/00-35/00 B29C 43/00-43/58

Claims (1)

(57) [Claims] 1. A method for manufacturing an interior molded article for a vehicle.
Te, and heating the crosslinked polyolefin resin foam, and compressing the heated foam 25 to 75% of the thickness, before
From the surface of both sides of the foam to the thickness of 0.2 mm
Making the difference in average foaming ratio 1.1 to 10.0 times, and attaching a skin material to the surface of the foam having a large average foaming ratio.
A step of bringing Ri, Hottosuta the small side of the surface average expansion ratio of the foam
Aggregate made of thermoplastic resin by pumping mold method
A method of manufacturing an interior molded product for a vehicle, comprising a step of integrally molding .