JP2002178754A - Automotive interior materials - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an interior trim for an automobile lightweight with high rigidity and high impact resistance even at a low temperature. SOLUTION: This interior trim for the automobile is formed by molding a resin composition comprising 100 pts.wt. of a polypropylene resin composition including glass fiber with specified material property, and 15-25 pts.wt. of an ethylene-butene copolymerized elastomer. The interior trim has solidified layers 5 on both surfaces, and a cavity 6 by the springback of glass fiber inside at a specified void ratio of 60-80%. Low-temperature falling ball impact is 5J or more, and the specific gravity of a principal part is 0.6 or less.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to an interior material for an automobile.

[0002]

2. Description of the Related Art Interior materials for automobiles need to satisfy a high level of generally contradictory properties of light weight, high strength and impact resistance. To achieve this, various proposals have been made so far. It has been done. For example, an automotive interior material obtained by injection foaming a short fiber long glass reinforced thermoplastic resin composition, or a long fiber long glass reinforced thermoplastic resin composition, injecting the fiber as much as possible without breaking the mold, Expansion molding method in which the cover is opened and expanded by springback (Japanese Patent Laid-Open No. 11-333878, Japanese Patent Laid-Open
No. 225843) has been proposed.

[0003]

However, in the case of using short and long glass fibers, the specific gravity can be reduced, but it is necessary to increase the wall thickness, that is, increase the weight, in order to secure sufficient rigidity. There is a problem. Moreover,
Since the appearance is deteriorated by the silver as the foaming agent, it is necessary to paint or laminate a skin or the like on the entire surface, and there is a problem that it takes time and cost. On the other hand, when long fibers and long glass fibers are used, a lightweight automotive interior material can be reliably obtained, but there is a problem that impact resistance, particularly low-temperature impact strength, is not at a sufficiently satisfactory level.

It is an object of the present invention to provide a lightweight automotive interior material having high rigidity and high impact resistance even at low temperatures.

[0005]

Means for Solving the Problems As a result of intensive studies on the above problems, the present inventors have found that a composition comprising a specific polypropylene, ethylene-butene copolymer elastomer and glass fiber is expanded to reduce the weight and increase the rigidity. The present invention was completed on the idea that an interior material for automobiles that achieves high impact resistance and excellent low-temperature ball impact could be obtained. Specifically, the automotive interior material according to the present invention is a polypropylene-based resin composition 1 comprising the following (A) and (B):
00 parts by weight and ethylene-butene copolymer elastomer 15
And a solidified layer on both surfaces, and has 60-80% of voids due to springback of glass fiber at the porosity specified in (C) below. And a low-temperature falling ball impact of 5 J or more and a specific gravity of a main part of 0.6 or less. (A) 60 to 80% by weight of a propylene-ethylene block copolymer satisfying the following (1) to (3) (1) Melt index (MI) = 50 to 70 g / 10
(230 ° C., 2.16 kg load) (2) Soluble at room temperature xylene: 15 to 20% by weight (3) Pentad fraction: 93 to 97 mol% (B) Glass fiber having a weight average fiber length of 2 to 10 mm: 20
４０40% by weight (C) Porosity = (volume of molded article after expansion−volume of composition before expansion [at the time of injection filling]) / (volume of molded article after expansion) × 1
00 (%)

Here, the content of the propylene-ethylene block copolymer in the polypropylene resin composition is 60%.
When the content is less than% by weight, the content of the glass fiber becomes too large, and the moldability deteriorates, and even if the molding can be performed, the appearance of the molded body deteriorates. On the other hand, if the content exceeds 80% by weight, the molded product does not expand satisfactorily, so that it becomes difficult to satisfy the impact resistance while maintaining the strength and rigidity required for interior materials for automobiles. Further, the propylene-ethylene block copolymer has a melt index (hereinafter referred to as MI) of 70 at 230 ° C. under a load of 2.16 kg.
If it exceeds g / 10 minutes, the obtained molded article does not satisfy sufficient impact resistance as an interior material for automobiles. On the other hand, MI
In the case of less than 50 g / 10 minutes, it is difficult to inject and fill the cavity, and the expansion moldability is also deteriorated, so that it is difficult to achieve a sufficient weight reduction.

Further, when the xylene-soluble content at room temperature of the propylene-ethylene block copolymer exceeds 20% by weight,
Rigidity and heat resistance decrease. On the other hand, if it is less than 15% by weight, the impact resistance is reduced. The pentad fraction of the xylene-insoluble portion at room temperature is 93 to 97 mol%, preferably 95 to 96 mol%. The pentad fraction is an isotactic fraction in a pentad unit (a unit in which five propylene monomers are consecutively isotactically bonded) in a resin molecular chain. A method for measuring this fraction is described, for example, in Macromolecules, Vol. 8, 1975.
Year) p. 687, 13 C-NMR, 400
It is a value measured using MHz.

The glass fiber is preferably E-glass or S-glass glass fiber having an average fiber diameter of 25 μm or less, more preferably 3 to 5 μm.
It is in the range of 20 μm. Glass fiber diameter is 3μm
If it is less than 1, the glass fiber does not adapt to the resin during pellet production, and it becomes difficult to impregnate the resin. On the other hand, if it exceeds 25 μm, cutting and chipping are likely to occur during melt kneading.
Using these thermoplastic resins and glass fibers, in producing pellets by a pultrusion method or the like, glass fibers are surface-treated with a coupling agent, and then by a sizing agent,
It is preferable to bundle 100 to 10,000 pieces.
It is more preferable to bundle them in a range of 0 to 5000.

The coupling agent can be appropriately selected from so-called silane coupling agents and titanium coupling agents which have been conventionally used. For example, γ-aminopropyltriethoxysilane, N-β-
(Aminoethyl) -γ-aminopropyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane,
Aminosilane and epoxysilane such as β- (3,4-epoxycyclohexyl) ethyltrimethoxysilane can be employed. In particular, it is preferable to employ the amino silane compound.

As the sizing agent, for example, urethane type, olefin type, acrylic type, butadiene type, epoxy type and the like can be used, and among these, urethane type and olefin type are preferable. Here, the urethane-based sizing agent is usually an oil-modified type, a moisture-curable type, or a moisture-curable type as long as it contains a polyisocyanate obtained by a polyaddition reaction between a diisocyanate compound and a polyhydric alcohol at a ratio of 50% by weight or more. One-pack type such as block type,
Either a two-pack type such as a catalyst-curable type and a polyol-curable type can be employed. On the other hand, a modified polyolefin resin modified with an unsaturated carboxylic acid or a derivative thereof can be used as the olefin sizing agent.

Here, the weight average fiber length of the glass fiber is
If it is less than 2 mm, the rigidity and impact resistance of the obtained interior material for automobiles are reduced. On the other hand, if it exceeds 10 mm, the appearance will deteriorate. In addition, if the length of the glass fiber contained in the interior material for automobiles is to be set to more than 10 mm, it is necessary to select a screw that does not easily break the glass fiber and the injection conditions, and then make the injection speed very slow. In addition, productivity is significantly reduced, which is disadvantageous in practical use. A more preferred weight average fiber length is 3 to 8 mm.

The method for achieving the weight average fiber length of the glass fibers is not particularly limited.
mm, preferably 3 to 50 mm, glass fibers having a length equal to the total length are arranged in parallel with each other, and a glass fiber reinforced block polypropylene-based resin pellet having a glass fiber content of 20 to 80% by weight is produced. Is preferred. Further, by mixing a block polypropylene resin containing no glass fiber and the glass fiber reinforced block polypropylene resin, the amount of glass fibers can be reduced to 20 to 4%.
It can be adjusted to 0% by weight. Here, when the glass fiber content is less than 20% by weight, expansion due to springback does not occur so much, and it becomes difficult to satisfy low-temperature impact resistance while maintaining strength and rigidity required for interior materials for automobiles. On the other hand, when the content exceeds 40% by weight, thin-wall molding becomes difficult, and even if molding can be performed, the appearance deteriorates. The weight average fiber length of the glass fiber in such an interior material for an automobile can be determined using a known measuring instrument after the interior material is ashed to make only the glass fiber.

Further, when the content of the ethylene-butene copolymer elastomer in 100 parts by weight of the polypropylene resin composition is less than 15% by weight, the impact resistance is lowered and the low temperature ball impact (-30 ° C.) is 5 J. Less than. On the other hand, 25
If the content exceeds 10% by weight, rigidity and heat resistance decrease, and
When the fluidity of the whole composition deteriorates and the initial thickness before expansion is small, expansion becomes difficult. Note that the ethylene-butene copolymer elastomer has substantially no crystallinity, and has an MI of 23.
It is preferably at least 20 g / 10 min at 0 ° C. and a load of 2.16 kg. When the MI is less than 20 g / 10 minutes, sufficient low-temperature ball-drop impact resistance cannot be obtained, and when the initial thickness before expansion is small, expansion becomes difficult. More preferably, MI is 30 g / 10 minutes or more.

The porosity of the interior material for automobiles is 60%.
If it is less than this, not only a sufficient low-temperature falling ball impact cannot be obtained, but also the weight reduction becomes insufficient. On the other hand, if it exceeds 80%, the internal voids are in a state like "su", and the physical properties of the interior material deteriorate. Here, the porosity is, as described above, (volume of molded body after expansion−volume of composition before expansion [at the time of injection filling]) / (volume of molded body after expansion) × 100 (%). The volume of the composition at the time of injection filling is also the volume of the mold cavity when the resin is filled before expansion.

[0015] The specific gravity of the main part of the interior material for automobiles is set at 0.1.
If it exceeds 6, sufficient weight reduction cannot be achieved. The reason why the specific gravity of the main part is specified is that the shape of the door panel or pillar, which is a typical part of the interior material for automobiles, is to secure and secure the space for inserting the plate-shaped part and the functional parts and foam members. This is because it is common to have a rising portion such as a convex portion for arm and armrest, and these portions cannot be identified with a plate-shaped portion due to design. The specific gravity of the main part is (weight of main part) / projected area of the mold.

Further, the solidified layers on both sides of the interior material for automobiles are skin layers formed by contact of a resin composition in a molten state with a mold, and if the thickness of the skin layer is not sufficient,
It is not preferable because a kind of squeak noise is generated when the interior material for automobile is pressed. The thickness of the skin layer is not particularly limited,
10 μm to 1 mm is usual. If the low-temperature ball impact is less than 5 J, the impact resistance is not practically satisfactory.
It is difficult to apply it to a door panel or the like in which a main part is likely to be impacted, which severely restricts its use as an interior material for automobiles.

The interior material for automobiles needs to have sufficient strength and impact resistance, and for this purpose, it is necessary to contain a certain amount of glass fiber, so that the specific gravity is high. Therefore, in order to further reduce the weight, it is necessary to reduce the initial thickness before expansion, and this initial thickness depends on the size of the automobile interior material and the specific gravity of the molding material, but should be 2 mm or less. Is preferred. The automotive interior material of the present invention, if necessary,
It also includes those in which skins are laminated on one side or both sides.

As a method of manufacturing the interior material for automobiles of the present invention, for example, a resin composition comprising the above-mentioned block polypropylene resin, glass fiber and ethylene-butene copolymer elastomer is injected into a mold and filled. Thereafter, while both surfaces of the interior material in contact with the mold surface are solidified and the resin composition is in a molten state, a method of opening the mold and generating springback by glass fiber can be employed. At this time, if necessary, a skin can be attached to the entire surface of the mold cavity surface or a part thereof to form a skin integral molded body.

Since the interior material for automobiles usually has a small initial thickness before expansion, a small amount of a foaming agent may be added as an expansion aid. In this case, the amount of the foaming agent to be added is 0.01 to 1% by weight based on 100% by weight of the total amount of the interior material for an automobile (excluding the case where the skin is present),
Preferably it is 0.05 to 0.5% by weight, more preferably 0.1 to 0.4% by weight. If a blowing agent is added more than necessary, silver is generated, which is not preferable. The foaming agent that can be used is not particularly limited. For example, chemical foaming agents such as azodicarbonamide, benzenesulfohydrazide, N, N-dinitropentamethylenetetramine, terephthalazide, and physical foaming such as pentane, butane, a fluorine compound, and water. Agents.

Further, if necessary, inorganic fillers such as talc, mica, calcium carbonate, etc.
Add other fibers such as aramid fiber, polyarylate fiber, carbon fiber, etc., various stabilizers such as antioxidant, light stabilizer, ultraviolet absorber, antistatic agent, coloring agent, nucleating agent, peroxide, etc. be able to.

[0021]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to the drawings. FIGS. 1 and 2 show a door panel 1 as an interior material for an automobile according to an embodiment of the present invention.
It is shown. 1A is a plan view of the door panel 1 for an automobile, and FIG. 1B is a cross-sectional view taken along line XX of FIG. 1A. The door panel 1 has a shape in which one corner of a substantially flat rectangular shape is cut out in a plan view, and has a plate-shaped portion 2 and a peripheral portion 4 formed by being raised from the periphery of the plate-shaped portion 2. An armrest 3 is formed substantially at the center of the door panel 1 and stands up from the plate portion 2 on the side opposite to the peripheral portion 4. Here, the armrest 3
It is composed of a side wall 3A raised from the plate-like portion 2 and an upper surface portion 3B covering an upper portion of the side wall 3A.

As shown in FIG. 2, the plate-like portion 2 and the upper surface portion 3 have a solidified layer 5 on both surfaces, and have a gap 6 formed therein by springback of glass fiber. In other words, each of these parts is a part whose thickness increases and its apparent density decreases due to expansion due to the recovery phenomenon of the entanglement of the glass fibers contained in the molding step. Here, the porosity of the void 6 is 60 to 80%, which is a porosity defined by the above-described equation.
On the other hand, the peripheral portion 4 and the side wall 3A are portions that are not substantially expanded, or even if expanded, their apparent density is hardly reduced. Note that the door panel 1 has a low-temperature falling ball impact of 5
J or more, the specific gravity of the main part (plate-like part 2, upper surface part 3B) is 0.
6 or less.

The thickness of the door panel 1 described above depends on the required characteristics depending on the vehicle type, the glass fiber content, the glass fiber length in the molded product, or the required characteristics such as the specific gravity of the main part, the elastic characteristics, and the heat insulating properties. It is determined by comprehensive judgment.

Next, a mold 7 for injection compression molding used for manufacturing the door panel 1 and a method for manufacturing the door panel 1 using this mold 7 will be described with reference to FIGS. FIGS. 3 and 4 are cross-sectional views of a main part of a mold 7 for molding the door panel 1. The mold 7 includes a fixed mold 8, and a movable mold 9 and a movable mold 10 that are provided in the fixed mold 8 so as to be able to advance and retreat. The space surrounded by 9 and the movable mold 10 is a cavity 11 for molding.

The fixed mold 8 is provided with a hot runner 12 into which a molten resin is injected, a gas injection pipe 13 into which gas is injected as necessary, and a gas exhaust pipe 14 through which the injected gas is discharged. . The hot runner 12 is provided with a molten resin shutoff valve 12A. The gas injection pipe 13 and the gas discharge pipe 14 are provided with a gas injection valve 13A and a gas discharge valve 14A, respectively. As the injection molding machine using the mold 7, a molding machine capable of injection compression molding or an injection molding machine equipped with a movable mold moving device in a general injection molding machine can be adopted.

A method of manufacturing the door panel 1 using the mold 7 configured as described above will be described. First, the polypropylene resin composition 1 comprising the above (A) and (B)
00 parts by weight and ethylene-butene copolymer elastomer 15
Is melt-kneaded with a screw. Subsequently, the movable mold 9 is moved with respect to the fixed mold 8.
And the movable mold 10 is moved to the position indicated by the dashed line in FIG. 3, that is, the clearance of the cavity 11 becomes t.
Set to the position of 1.

In this state, a predetermined amount of the resin composition melt-kneaded is weighed, and a clearance t2 is introduced into the cavity 11 from the hot runner 12 with the molten resin shut-off valve 12A opened.
Inject the amount corresponding to. The amount corresponding to t2 is an amount that fills the entire cavity 11 at the time of compression in the next step. When such a molten resin composition is injected, the injection amount of the resin is usually ２ or less of the volume of the cavity 11, and since the injection resin pressure is low, the orientation of the resin and the glass fiber is small. Or practically does not happen.

After the injection of the resin composition into the cavity 11, for example, two seconds before the completion of the injection to immediately after the completion of the injection, the movable resin mold 10 is advanced to compress the molten resin composition,
The cavity 11 is completely filled. As a result, the surface of the door panel 1 starts to be cooled by the mold 7,
Even minute irregularities on the surface of the mold 7 are completely transferred. After the surface of the movable mold 10 is cooled to some extent by the mold clamping of the movable mold 10 and the skin layer (solidified layer 5) is formed, while the inside is in a molten state, the movable mold 10 is moved to the clearance t3 which is the thickness of the door panel 1. Then, the molten resin in the interior is expanded by retracting to the position shown in FIG. 2 and spring back is caused inside by the glass fiber, and then cooled, whereby the door panel 1 is formed. Thereafter, the door panel 1 is taken out by opening the movable mold 9.

According to the above-described embodiment, the following effects can be obtained. (1) a propylene-ethylene block copolymer in a polypropylene resin composition that is a raw material resin of the door panel 1;
Since the content of the glass fiber is within the range of the present invention, the moldability is high, and the appearance of the molded body is also good. Also,
Since the molded product expands sufficiently, impact resistance can be satisfied while maintaining the strength and rigidity required for interior materials for automobiles. (2) Propylene-ethylene block copolymer 230
MI under a load of 2.16 kg at 50 to 70 g /
Since the time is 10 minutes, the door panel 1 has sufficient impact resistance and the injection filling into the cavity 11 can be easily performed, so that the weight can be reduced.

(3) Since the propylene-ethylene block copolymer has a xylene-soluble content at room temperature of 15 to 20% by weight, the rigidity, heat resistance and impact resistance of the obtained door panel 1 can be improved. . (4) Since the weight average fiber length of the glass fiber is 2 to 10 mm, the rigidity and impact resistance of the obtained door panel 1 can be improved, and the appearance is also good.

(5) Since the content of the ethylene-butene copolymer elastomer in 100 parts by weight of the polypropylene resin composition is 15 to 25% by weight, the impact resistance of the door panel 1 obtained can be improved. , Low temperature drop impact (-
30 ° C.) can be set to 5 J or more,
The heat resistance can be improved. (6) Since the porosity of the door panel 1 is 60 to 80%,
It is possible to obtain a sufficient low-temperature ball-drop impact and also achieve a reduction in weight. (7) Since the low-temperature falling ball impact is 5 J or more, which is a practically satisfactory low-temperature impact resistance, it can be applied to a portion to which an impact is easily applied, and can be used as an interior material for automobiles.

It should be noted that the present invention is not limited to the above embodiment, and modifications and improvements as long as the object of the present invention can be achieved are included in the present invention. For example, in the above-described embodiment, the door panel 1 is adopted as an interior material for an automobile. However, the invention is not limited to this, and another interior material for an automobile such as a pillar may be used. Although the skin is not laminated on the surface of the door panel 1, the skin may be laminated on part or all of the surface.

In the above-described embodiment, as a method of manufacturing the door panel 1, injection compression molding without injecting gas is used, but the method is not limited to this. That is, after the retreat of the movable mold 10 is started, a normal temperature or cooled nitrogen gas or the like is injected from the gas injection pipe 13 at a gas pressure in the range of 0.01 to 20 MPa, preferably in the range of 0.1 to 5 MPa. May be adopted. By injecting the gas as described above, the expansion by the glass fiber is assisted, and the molded product is pressed against the surface of the mold after the expansion, so that the mold transferability and the appearance can be improved. Furthermore, while controlling the pressure of the injected gas to a certain level as necessary, the gas is evacuated, and the gas is circulated through the molded article, whereby cooling of the molded article can be promoted, which greatly contributes to the improvement of the molding cycle. Things. In addition, the specific structure, shape, and the like at the time of carrying out the present invention may be other structures and the like as long as the object of the present invention can be achieved.

[0034]

The present invention will now be described more specifically with reference to examples and comparative examples. [Example 1] Glass fibers (13 µm) are arranged in parallel,
50 parts by weight of glass fiber reinforced propylene-ethylene block copolymer pellets having a content of 60% by weight and a length of 16 mm (containing 3% by weight of maleic anhydride-modified polypropylene and the remaining block PP being J-5066HP) , Melt index (MI) [230 ° C, 2.1
Propylene-ethylene block copolymer (J-5066HP, manufactured by Idemitsu Petrochemical Co., Ltd., room temperature xylene solubles: 16% by weight, pentad fraction: 96.8 mol%) with a load of 6 g / 10 min. Parts by weight, ethylene-butene copolymer elastomer (EBR) (Tuffmer IT10
3, 20 parts by weight, manufactured by Mitsui Chemicals, Inc., MI = 60 g / 10 min), and 0.3 parts by weight of a blowing agent (Polyslen EE115, manufactured by Eiwa Chemical Co., Ltd.) were dry-blended to 0.3 parts by weight based on the total composition. These were used as raw materials for molding. (Block PP:
(70 parts by weight / glass fiber: 30 parts by weight / EBR: 20 parts by weight)

The injection molding machine has a mold clamping force of 850 t (Mitsubishi 8
50MGW), and a screw having a compression ratio of 1.8 was used in order to minimize breakage of the glass fiber. As the mold 7, the door panel 1 [approximate dimensions: 700 mm wide x 500 vertical)
mm], and an injection molding apparatus having a mold structure equipped with an IPM unit (manufactured by Idemitsu Petrochemical Co., Ltd.) for moving the movable mold 10 back and forth so that the volume of the cavity 11 can be changed. .

After the molding raw material is melt-kneaded and plasticized and measured, the thickness of the cavity 11 of the plate portion 2 of the door panel 1 is reduced to 2 m.
m (t1 in FIG. 3) and set to 1.3 mm (t1 in FIG. 3).
A molten resin (resin temperature: 240 ° C.) corresponding to 2) was injected. One second after the start of the injection, the movable mold 10 is advanced, and the compression force 200 is reduced until the movable mold 10 corresponds to the thickness t2 of the cavity 11.
t and melt the molten resin into the cavity 11 (mold temperature: 6).
(0 ° C.) (filling time 2 seconds). One second after the end of the compression, the movable mold 10 was moved to a thickness of 3.3 mm for the cavity 11.
(T3 in FIG. 4) and the tube was retracted and expanded.

Two seconds after the start of the retreat of the movable mold 11, nitrogen gas of 2 MPa was injected into the resin from the gas injection pipe 13.
Thereafter, after cooling and solidification and gas exhaustion, the mold 7 was opened to obtain the door panel 1. The evaluation results of the obtained door panel 1 are shown below. In addition, the average glass fiber length, after ashing the test piece,
The image was directly photographed at a magnification of 10 times with a universal projector, and the image was used to determine the glass fiber length with a digitizer. Also, -30
The dropping ball impact strength at ℃ was obtained by calculating the maximum height at which a 535 g steel ball was dropped at -30 ° C and not broken, and the energy was calculated. (1) Average fiber length of glass fiber: 5.8 mm (2) Expansion ratio: 2.5 times (3) Porosity: 60%, (4) Specific gravity: 0.58 (5) Impact strength at -30 ° C falling ball: 6J

[Comparative Example 1]
A door panel was obtained by molding in the same manner as in Example 1 except that t3 was set to 2.6 mm. The evaluation results are shown below. (1) Average fiber length of glass fiber: 5.6 mm (2) Expansion ratio: 2 times (3) Porosity: 50%, (4) Specific gravity: 0.58 (5) Falling ball impact strength at -30 ° C: 4J

[Comparative Example 2] Molding was performed in the same manner as in Example 1 except that the ethylene-butene copolymer elastomer was not used.
I got a door panel. The evaluation results are described below. (1) Average fiber length of glass fiber: 5.1 mm (2) Expansion ratio: 2 times (3) Porosity: 50%, (4) Specific gravity: 0.58 (5) Impact strength at -30 ° C falling ball: 4J

Comparative Example 3 Glass fiber reinforced propylene
75 parts by weight of an ethylene block copolymer pellet and a propylene-ethylene block copolymer (J-5066HP,
Let's mold the door panel under the same conditions as in Example 1 except that 25 parts by weight of Idemitsu Petrochemical Co., Ltd.) and 20 parts by weight of ethylene-butene copolymer elastomer (EBR: Tuffmer IT103, manufactured by Mitsui Chemicals, Inc.) are used. However, the initial thickness was too small to be filled. That is, the specific gravity is 0.6
It means that the following door panels cannot be manufactured.

Comparative Example 4 Glass Fiber Reinforced Propylene
30 parts by weight of an ethylene block copolymer pellet and a propylene-ethylene block copolymer (J-5066HP,
Let's mold a door panel under the same conditions as in Example 1, except that 70 parts by weight of Idemitsu Petrochemical Co., Ltd.) and 20 parts by weight of ethylene-butene copolymer elastomer (EBR: Tuffmer IT103, manufactured by Mitsui Chemicals, Inc.) are used. But did not expand more than twice. In addition, when the cross section was observed with a microscope, it did not expand uniformly, was in a state of "su", and varied at -30 ° C falling ball impact strength of 3 to 4J.

[0042]

According to the present invention, a resin composition comprising 100 parts by weight of a predetermined polypropylene-based resin composition and 15 to 25 parts by weight of an ethylene-butene copolymer elastomer is molded, and solidified layers are formed on both surfaces. And a gap of 60 to 80 due to spring back of glass fiber inside.
%, The falling impact at low temperature is 5 J or more, and the specific gravity of the main part is 0.1%.
Since the interior material for an automobile is 6 or less, it is possible to provide a lightweight interior material for an automobile having high rigidity and high impact resistance even at a low temperature.

[Brief description of the drawings]

FIG. 1 is a diagram showing a door panel as an interior material for a vehicle according to an embodiment of the present invention.

FIG. 2 is a partially enlarged sectional view of a main part in the embodiment of FIG.

FIG. 3 is a cross-sectional view showing a molding die in a state where a molten resin is filled in the embodiment of FIG. 1;

FIG. 4 is a cross-sectional view showing a molding die in a state where a molten resin is expanded in the embodiment of FIG. 1;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Door panel as interior material for automobiles 2 Plate-shaped part 5 Solidified layer 6 Void 7 Mold

Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (reference) (C08L 53/00 C08L 23:22) 23:22) B29K 23:00 B29K 23:00 105: 12 105: 12 B29L 31 : 58 B29L 31:58 B60J 5/00 501A (72) Inventor Yoshiaki Saito 1 Anezaki Coast, Ichihara City, Chiba Prefecture 1 (72) Inventor Kimiyuki Yano 1 Anezaki Coast 1 Ichihara City, Ichihara City, Chiba Prefecture (72) Inventor Sakaguchi Yuo 1-4-1, Chuo, Wako-shi, Saitama F-term in Honda R & D Co., Ltd. (Reference) 3D023 BA01 BB08 BC01 BD03 BE04 BE09 BE31 4F206 AA11 AA11F AA11K AB11 AB25 AH26 JA07 JF01 JF02 4J002 BB052 BP021 FD 030 006 006 GF00 GL01 GT00

Claims (2)

[Claims] 1. A resin composition comprising 100 parts by weight of a polypropylene resin composition comprising the following (A) and (B) and 15 to 25 parts by weight of an ethylene-butene copolymer elastomer, and molded on both surfaces. In addition to having a solidified layer, the inside thereof has a void due to glass fiber spring back at a porosity specified in the following (C) of 60 to 80%, a low-temperature falling ball impact of 5 J or more, and a specific gravity of a main part of 0.6 or less An interior material for automobiles, characterized in that: (A) 60 to 80% by weight of a propylene-ethylene block copolymer satisfying the following (1) to (3) (1) Melt index (MI) = 50 to 70 g / 10
(230 ° C-2.16 kg load) (2) Room temperature xylene solubles: 15 to 20 wt% (3) Pentad fraction: 93 to 97 mol% (B) Glass fibers having a weight average fiber length of 2 to 10 mm: 20
４０40% by weight (C) Porosity = (volume of molded body after expansion−volume of composition before expansion [at the time of injection filling]) / (volume of molded body after expansion) × 1
00 (%) 2. The interior material for an automobile according to claim 1, wherein the ethylene-butene copolymer elastomer has substantially no crystallinity, and has a melt index (MI) at 230 ° C. and a load of 2.16 kg. An interior material for automobiles, which is at least 20 g / 10 minutes.