JPH0691774A - Manufacture of composite foam-molded form - Google Patents

Abstract

PURPOSE:To obtain a molded form having a low cost, a light weight and high rigidity by charging special resin composition containing foaming agent in a mold, integrating it with a skin material under a predetermined pressure, foaming the composition, and cooling to solidify its foamed base material layer. CONSTITUTION:The method for manufacturing a composite foamed molded form comprises the steps of charging base material forming polypropylene resin composition 4 melted at 180-240 deg.C of a decomposing temperature or higher of foaming agent and containing the agent in a mold stamping lower mold 2 of 30-80 deg.C, closing upper and lower molds 1, 2 within 10sec after the end of charging, clamping the molds by pressure of 20-70kg/cm<2>, integrating the base material layer made of the composition 4 with a skin material 3, lifting the mold 2 within a range of 1.1-twice as large as the thickness of a flat part before a thickness of one of solidified layers 6 formed on both the surfaces, foaming the composition 4, and then cooling to solidify a foamed base material layer 10 made of the composition 4.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a method for producing a composite foam molded article, and more particularly to a method for producing a lightweight and highly rigid composite foam molded article which can be used for applications such as automobile interior materials. .

[0002]

BACKGROUND OF THE INVENTION Automotive interior materials manufactured by mold stamping molding include door rims,
Rear package trim, seat back garnish,
There is an instrument panel etc.

The base material of the above-mentioned automobile interior material is usually composed mainly of polypropylene, and is composed of a composition to which talc or the like as a filler is added by 0 to 30% by weight. These base materials have ribs and bosses, are highly rigid base materials, and are compositely integrated with the skin material. The mold stamping molding method adopted in the production of the automobile interior material as described above is a rational composite molding method in which the molding process is simplified as compared with the injection molding method.

However, in the conventional mold stamping molding method, the density of the substrate is 0.91 to 1.1 g / cm 3.
There is a problem that the molded product obtained is in the range of ³ and is heavy. Nowadays, weight reduction of automobiles has become an important theme for improving fuel efficiency of vehicles and improving environmental problems.

Further, the mold stamping molding method capable of integrally molding the skin material and the base material at the same time is an advantageous molding method in terms of cost. Compared to the injection molding method, the mold stamping molding method is low-pressure molding, and is also suitable for foam molding of the base material as a lightweight method from this viewpoint.

However, conventionally, it has been difficult to obtain good foaming in mold stamping molding.
Therefore, it is desired to develop a method capable of producing a lightweight and highly rigid composite foam molded article by the mold stamping molding method.

[0007]

SUMMARY OF THE INVENTION The present invention is intended to solve the problems associated with the prior art as described above, and is lightweight and
It is an object of the present invention to provide a method for producing a composite foam-molded article that can obtain a highly rigid composite foam-molded article.

[0008]

SUMMARY OF THE INVENTION A first method for producing a composite foam molded article according to the present invention comprises a step of setting a skin material in the vicinity of an upper die for mold stamping molding at a die temperature of 10 to 50 ° C., in advance.
A lower mold for mold stamping molding of a polypropylene resin composition for forming a base material containing a foaming agent, which is melted at a decomposition temperature of the foaming agent or higher and a temperature of 180 to 240 ° C., at a mold temperature of 30 to 80 ° C. The step of charging the surface and closing the upper and lower molds within 10 seconds after the completion of charging of the polypropylene resin composition and clamping the mold at a pressure of 20 to 70 kg / cm ² to shape the substrate shape and at the same time to mold the polypropylene resin composition. A step of integrating a base material layer made of a material and a skin material,
Before the thickness of one of the solidified layers formed on both surfaces of the polypropylene resin composition layer by the mold clamping reaches 1.0 mm, the thickness of the polypropylene resin composition layer at the flat surface portion having no boss portion or rib portion. The step of raising the upper mold within the range of 1.1 to 2 times to foam the polypropylene resin composition, and subsequently cooling and solidifying the foamed base material layer made of the polypropylene resin composition. It is characterized in that a composite foam molded article is obtained after that.

The second aspect of the composite foam molded article according to the present invention
The production method of the method is as follows:
A polypropylene resin composition for forming a base material containing a foaming agent, which has been melted at a temperature of 240 ° C to a mold temperature of 30 to 80 ° C.
The step of charging the surface of the lower die for stamping and molding of the mold, and the mold temperature of 10 to 50 immediately after or at the same time as the charging of the polypropylene resin composition.
The step of setting a skin material near the upper die for stamping molding at ℃, and closing the upper and lower dies within 10 seconds after the completion of charging of the polypropylene resin composition, pressure 20 to 7
Both the step of performing mold clamping with 0 kg / cm ² to form the base material shape and at the same time integrating the base material layer made of the polypropylene resin composition and the skin material, and the polypropylene resin composition layer by the mold clamping. Before the thickness of one of the solidified layers formed on the surface reaches 1.0 mm, within a range of 1.1 to 2 times the thickness of the flat surface portion having no boss portion and rib portion of the polypropylene resin composition layer. A step of raising the upper mold to foam the polypropylene resin composition, and subsequently,
It is characterized in that a composite foam molded article is obtained through a step of cooling and solidifying a foam base material layer made of a polypropylene resin composition.

[0010]

DETAILED DESCRIPTION OF THE INVENTION The method for producing a composite foam-molded article according to the present invention will be specifically described below. The composite foam molded article manufactured by the method for manufacturing a composite foam molded article according to the present invention is composed of a foam base material layer made of a polypropylene resin composition and a skin material.

First, the polypropylene resin composition for forming a base material used for producing a composite foam molded article in the present invention will be described. Polypropylene resin composition for forming a base material The polypropylene resin composition for forming a base material used in the present invention comprises a polypropylene resin [1] and a foaming agent [2]. In addition to these components, this composition may contain a filler [3].

The polypropylene resin [1] used in the present invention is a resin containing a propylene homopolymer or a propylene block copolymer (A) as a main component, and specifically, a propylene homopolymer or a propylene block. Copolymer (A) 50 to 100 parts by weight, preferably 70
~ 100 parts by weight, ethylene homopolymer, 4 carbon atoms
0 to 50 parts by weight of a polymer (B) selected from the group consisting of α-olefin homopolymers of 10 to 10 and α-olefin copolymers of 2 to 10 carbon atoms, preferably 0.
30 parts by weight. However, the propylene block copolymer is not included in the above-mentioned copolymer between α-olefins having 2 to 10 carbon atoms. Also,
The total amount of the above components (A) and (B) is 100 parts by weight.

The propylene block copolymer is an ordinary block copolymer, and examples thereof include the following copolymers. (1) selected from the group consisting of crystalline propylene polymer block (a), ethylene polymer block (b), ethylene-propylene copolymer rubber, styrene-butadiene rubber and styrene-butadiene block copolymer A propylene / ethylene block copolymer comprising a rubber block (c) composed of one or more rubbers described above. (2) A propylene block copolymer comprising a crystalline propylene polymer block (a) and the rubber block (c) as described above.

The above-mentioned propylene / ethylene block copolymer is obtained by polymerizing olefins in one polymerization reaction system in the presence of a stereoregular catalyst, preferably a catalyst comprising a transition metal component with a support and an organoaluminum compound. It is a so-called non-polymer blend type copolymer obtained by the above, and its specific production method is described in detail in JP-A-52-98045 and JP-B-57-26613 by the present applicant. . Here, "polymerizing in one polymerization reaction system" means that a polymer mixture is produced by sequentially producing each component of a propylene / ethylene block copolymer in a single or a plurality of reactors. That is, the deactivating operation of the catalyst is not usually performed during the production of the respective constituent components of the propylene / ethylene block copolymer.

The above-mentioned propylene / ethylene block copolymer and propylene block copolymer are not limited to one kind of polymer obtained by polymerizing in one polymerization reaction system, and two kinds of polymers separately polymerized. It may be a propylene / ethylene block copolymer, a mixture of propylene block copolymers, or a so-called polymer blend type copolymer.

Specific examples of the α-olefin constituting the above-mentioned α-olefin homopolymer having 4 to 10 carbon atoms include butene-1, pentene-1,4-methylpentene.
-1, hexene-1, heptene-1, octene-1, nonene-1, decene-1 and the like.

Further, as the above-mentioned copolymer between α-olefins having 2 to 10 carbon atoms, specifically, ethylene.
Propylene copolymer rubber (EPR), ethylene butene
-1 copolymer rubber (EBR), propylene / ethylene copolymer rubber (PER), propylene / butene-1 copolymer rubber (PBR) and the like. However, the copolymer here does not include a propylene block copolymer.

The polypropylene resin used in the present invention has a melt flow rate (ASTMD 1238, L).
Is usually 10 to 100 g / 10 minutes, preferably 20 to 60
Within the range of g / 10 minutes.

In the present invention, the polypropylene resin [1] is 68 per 100% by weight of the total amount of the polypropylene resin [1], the foaming agent [2] and the filler [3].
It is used in a proportion of -99.8 wt%, preferably 69-94.5 wt%.

In the present invention, in order to form bosses and ribs with a pressure as low as possible, it is desirable that the melt flow rate of the polypropylene resin be within the above range. Specific examples of the foaming agent [2] used in the present invention include azodicarbonamide (ADCA), N, N'-.
Organic blowing agents such as dinitrosopentamethylenetetramine, 4,4'-oxybis (benzenesulfonylhydrazide), diphenylsulfone-3,3'-disulfonylhydrazide, p-toluenesulfonylsemicarbazide, trihydrazinotriazine, sodium hydrogencarbonate, Inorganic foaming agents such as ammonium hydrogen carbonate and ammonium carbonate can be used. Among them, azodicarbonamide (ADCA), N, N′-dinitrosopentamethylenetetramine and trihydrazinotriazine are preferable as the organic foaming agent, and sodium hydrogencarbonate is preferable as the inorganic foaming agent.

In the present invention, the blowing agent [2] is preferably 0.2 to 2% by weight, preferably 100% by weight of the total amount of the polypropylene resin [1], the blowing agent [2] and the filler [3]. Is used in a proportion of 0.5 to 1.0% by weight.

When the foaming agent is used in the above proportion, the foaming ratio of the foaming base material layer of the polypropylene resin composition other than the boss and the rib is 1.1 to 1.
It can be multiplied by 2.0.

Specific examples of the filler [3] used in the present invention include glass fiber, talc, calcium carbonate, barium sulfate and the like. In the present invention, glass fiber and talc are particularly suitable from the viewpoint of improving foamability.

In the present invention, the filler [3] is 0 to 30% by weight, preferably 5 to 5% by weight based on 100% by weight of the total amount of the polypropylene resin [1], the foaming agent [2] and the filler [3]. Used in a proportion of 30% by weight.

By mixing the fillers in the above proportions, it is possible to improve the rigidity, heat resistance and dimensional stability of the obtained composite foam molded article. Therefore, in the present invention, the fillers as described above are used. It is preferable to use.

Skin Material The skin material used in the present invention may be a non-woven fabric, cloth, fabric or the like, or a composite material obtained by adhering these to a resin foam such as polypropylene foam or polyurethane foam. When these composite materials are used as a skin material, they are laminated so that the foam surface of the composite material is in contact with the base material, that is, the foam layer made of the polypropylene resin composition.

Further, in the present invention, leather such as polyvinyl chloride resin (PVC), thermoplastic elastomer (TPE), polyurethane (PU) or the like, or resin foam such as leather and polypropylene foam or polyurethane foam. A composite material obtained by bonding and is also used as a skin material. When using these composite materials as a skin material,
As in the case of the above-mentioned composite material, the composite material is laminated so that the foam surface of the composite material is in contact with the base material, that is, the foam layer of the polypropylene resin composition.

Manufacturing Method Next, a method for manufacturing the composite foam molded article according to the present invention will be described with reference to the drawings. As shown in FIG. 1, the mold temperature is 10 to 50.
The skin material 3 is set in the vicinity of the upper die 1 for mold stamping molding at ℃.

In the present invention, since the upper die 1 will come into contact with the skin material 3 later, the die temperature of the upper die 1 is preferably 10 to 50 ° C. in order not to damage the skin material 3. Is preferably 10 to 30 ° C.

Next, at the decomposition temperature of the foaming agent or higher, and
A polypropylene resin composition for forming a substrate containing a foaming agent, which is melted at a temperature of 180 to 240 ° C., preferably 180 to 220 ° C., is applied to the surface of the lower mold 2 for mold stamping molding at a mold temperature of 30 to 80 ° C. Then, the polypropylene resin composition 4 is charged.

The polypropylene resin composition to be charged is uniformly prepared by previously mixing the polypropylene resin [1], the foaming agent [2], and the filler [3] in the above proportions using a mixing and stirring device such as a Henschel mixer. Prepare by mixing. Here, "preparing a polypropylene resin composition to be precharged" means (1) preparing the polypropylene resin composition by melting it before the step of setting the above-mentioned skin material, (2) skin Preparing the polypropylene resin composition by melting while setting the material, and (3) preparing the polypropylene resin composition by melting after the step of setting the skin material is completed. Means

When the polypropylene resin composition is melted at the temperature as described above by using the extruder equipped in the mold stamping molding machine, the foaming agent is decomposed and the resin composition starts to foam. Therefore, in the present invention, when the polypropylene resin composition is melted at the above temperature, it is necessary to immediately charge the surface of the lower mold 2 with the resin composition. Therefore, particularly when the polypropylene resin composition is prepared before the step of setting the skin material, the skin material must be quickly set.

Further, although the foamed cells (air bubbles) are generated by the melting of the polypropylene resin composition, it is desirable to minimize the collapse of the foamed cells due to the flow of the resin composition. Therefore, it is preferable to make the flow distance to the lower mold 2 of the polypropylene resin composition in a molten state as short as possible.

As described above, since the surface of the lower mold 2 is charged with the molten polypropylene resin composition, if the mold temperature of the lower mold 2 is too low, the charged polypropylene resin composition is rapidly cooled. This causes poor flowability of the polypropylene resin composition, poor foaming, and poor appearance of the molded product. Therefore, in the present invention, the mold temperature of the lower mold 2 is 30 to 80 ° C, preferably 40 to 60 ° C.

In the present invention, it is preferable that the polypropylene resin composition in a molten state is formed into a sheet and charged on the surface of the lower mold 2. The area of the molten polypropylene resin composition charged on the surface of the lower mold 2 is preferably 50% or more of the projected area of the lower mold.

In the present invention, from the viewpoint of providing the base material with strength, as shown in FIG. 1, a recess 5 for forming a rib portion, and further a boss portion for forming a rib portion are formed on the surface of the lower mold 2. It is desirable that the recessed part be provided. .

Then, as shown in FIG. 2, the upper and lower molds 1 and 2 are closed within 10 seconds after the completion of charging of the polypropylene resin composition, and the mold is clamped at a pressure of 20 to 70 kg / cm ² to give the base material shape. Simultaneously with the shaping, the base material layer made of the polypropylene resin composition 4 and the skin material 3 are integrated.

The step of setting the skin material 3 near the upper die 1 for stamping molding may be performed immediately before the step of clamping. That is, the skin material 3 can be set in the vicinity of the upper mold 1 for mold stamping molding at a mold temperature of 10 to 50 ° C. immediately after or at the same time as the charging of the polypropylene resin composition.

Then, as shown in FIGS. 3, 4 and 5, one of the solidified layers 6 formed on both surfaces of the polypropylene resin composition 4 (base material layer) by this mold clamping has a thickness of 1.0 mm. Polypropylene resin composition 4 before reaching
Of the polypropylene resin composition 7 in a molten state by raising the upper mold 1 within a range of 1.1 to 2 times the thickness of the flat surface portion having no boss portion (not shown) and rib portion 8 Let

When the rising timing of the upper die 1 is delayed,
Solidified layer 6 on both surfaces of polypropylene resin composition 4
Formation proceeds, and the polypropylene resin composition 4 does not foam. In the present invention, the solidified layer 6 constitutes a part of the polypropylene resin composition 4. Since the thickness of the polypropylene resin composition 4 in the plane portion not having the boss portion and the rib portion 8 is usually 2 to 3 mm, when the thickness of the solidified layer 6 becomes 1 mm or more, substantially the foamed portion is extremely reduced. And it will not foam. Therefore, it is preferable to set the rising start time of the upper mold 1 so that the thickness of the solidified layer 6 of the polypropylene resin composition 4 is less than 1.0 mm. Depending on the thickness of the polypropylene resin composition 4 at the flat surface, this thickness is 2 m.
In the case of m, 1 to 1 from the time when the polypropylene resin composition 4 is completely filled on the surface of the lower mold 2 by the mold clamping.
It is preferable to raise the upper mold 1 by 3 to 4 mm after 2 seconds. The polypropylene resin composition 4 continues to generate foam cells.

Next, the foamed base material layer 10 formed of the solidified layer 6 made of the polypropylene resin composition 4 and the foamed layer 9 is cooled and solidified. The cooling and solidification can be performed using upper and lower molds, but in the present invention, as shown in FIG. 4, it is preferable that the solidification is performed in the state where the mold is clamped, and the foaming base material layer 10 shrinks. Then, when the mold clamping pressure decreases, it is desirable that the pressure follows the mold clamping pressure before being cooled and solidified.

Finally, a molded product composed of the skin material 3 and the foam base material layer 10 having the rib portion 8 as shown in FIG. 6 is taken out. In the composite foam-molded article manufactured through the above-described steps, the foaming ratio of the rib portion 8 of the foaming base material layer 10 and the flat portion having no boss portion is 1.1 to 2.0 times. Compared with the composite foamed molded product manufactured by the mold stamping molding method of (1), it is lightweight and has high rigidity.

[0043]

According to the present invention, a low cost, lightweight and highly rigid composite foam molded article can be obtained.

The composite foamed molded article can be used for applications requiring a particularly light weight, such as automobile interior materials. Hereinafter, the present invention will be described with reference to examples, but the present invention is not limited to these examples.

The test methods for the falling ball impact test and the bending test are as follows. (1) Falling ball impact test A 500 g steel ball is dropped on the surface of the seat back garnish fixed to the sheet on the skin material side. 80 at 23 ° C
cm, a steel ball is dropped from a height of 40 cm at −30 ° C. and the seat back garnish breaks. (2) Bending test The bending test was performed according to ASTM D 790, and the elastic gradient (value obtained by dividing the bending load within the elastic limit by the deformation amount) was obtained. However, the distance between spans was 48 mm and the bending speed was 5 mm / min.

[0046]

[Example 1] First, a 1.0-mm-thick two-layer body made of polyvinyl chloride resin leather and a non-woven fabric as a skin material was prepared.
The mold temperature was set near the upper mold of 30 ° C.

Next, the melt flow rate (ASTM
D 1238, L) 45 g / 10 min propylene block copolymer [ethylene / propylene copolymer rubber (EP
R) content: 10% by weight, ethylene content: 20 mol%] 6
5 parts by weight, glass fiber reinforced polypropylene [glass fiber content: 30% by weight] 30 parts by weight, foaming agent [azodicarbonamide (ADCA) and low density polyethylene (L
DPE) weight ratio (ADCA / LDPE) 10/9
Manufactured as a masterbatch with both set to 0] 5
1 part by weight was mixed with a tumbler mixer, and this mixture was put into an extruder equipped in a mold stamping molding machine [made by Ikegai Tekko KK]. The temperature of the extruder cylinder and die was set to 210 ° C. when the above mixture was charged into the extruder.

Next, the molten resin which had begun to foam was charged in the form of a sheet onto a mold under a mold temperature of 40 ° C. The charging position at this time occupied almost 90% of the area of the lower mold.
The amount of resin charged was 500 g. A seat back garnish mold was used as the mold.

Upon completion of charging the molten resin, the upper and lower molds were closed and a pressure of 40 kg / cm ² was applied. Then, at a time of 1.5 seconds after the completion of the mold clamping at a pressure of 40 kg / cm ² , the upper mold was raised by 1.5 mm and then 60
After holding for 2 seconds and opening the mold, a molded product as shown in FIG. 6 was obtained.

The solidified layer 6 (non-foaming layer forming a part of the foaming base material layer 10) formed on the surface of the foaming base material layer 10 of the obtained molded product had a thickness of 0.4 mm, and Timber layer 1
The thickness of the plane portion having no rib portion 8 of 0 is 3.9 m.
m (including the thickness of the solidified layer 6). The size of the foam cells in the foam base material layer 10 is 50 to 500 μm.
Was in the range.

In the molded product, the polyvinyl chloride resin leather as the skin material and the base material made of the above mixture were firmly bonded to each other via the nonwoven fabric lined with the polyvinyl chloride resin leather.

The rib portion 8 of the formed base material is not foamed, but the flat surface portion of the base material is foamed as shown in FIG. 6, and its specific gravity is 0.75, and the specific gravity of the unfoamed sheet is 0.97. 22% lighter than the previous model.

The molded product was attached to a sheet, and a falling ball impact test was conducted on the skin side of the seat back garnish. Then
It was found that there was no problem in impact strength. However, the falling points of the steel balls are 9 points including the rib surface portion and the flat surface portion.

A bending strength test was carried out by taking a test piece from the flat surface portion of the molded product having no rib portion 8 and the elastic gradient was 32 kg / cm.

[0055]

Example 2 In Example 1, 1 part of talc was used instead of 30 parts by weight of the glass fiber reinforced polypropylene of Example 1.
The same procedure as in Example 1 was carried out except that 5 parts by weight was used and the amount of the propylene / ethylene block copolymer in Example 1 was 80 parts by weight.

The solidified layer 6 formed on the surface of the foaming base material layer 10 of the obtained molded product had a thickness of 0.4 mm, and the thickness of the foaming base material layer 10 at the flat surface portion having no rib portion 8 was 3 mm. It was 0.5 mm (including the thickness of the solidified layer 6). Also,
The size of the foam cells in the foam base material layer 10 is 50 to 7
It was in the range of 00 μm.

In the molded product, the polyvinyl chloride resin leather as the skin material and the base material made of the above mixture were firmly bonded to each other via the nonwoven fabric lined with the polyvinyl chloride resin leather.

The rib portion 8 of the formed base material is not foamed, but the flat surface portion of the base material is foamed as shown in FIG. 6, and its specific gravity is 0.82, and the specific gravity of the unfoamed sheet is 1.0. 1 compared to
The weight was reduced by 8%.

As a result of a falling ball impact test of the molded product, it was found that the above standards were met and there was no problem in impact strength. The elastic gradient of the flat surface portion of the molded product having no rib portion 8 was 30 kg / cm.

[0060]

[Third Embodiment] In the first embodiment, the upper die rising distance is set to 2.
The same procedure as in Example 1 was performed except that the thickness was 0 mm.

The solidified layer 6 formed on the surface of the foamed base material layer 10 of the obtained molded article had a thickness of 0.4 mm, and the thickness of the flat surface portion of the foamed base material layer 10 having no rib portion 8 was 4 mm. It was 0.5 mm (including the thickness of the solidified layer). The size of the foam cells in the foam base material layer 10 is 50 to 1,
It was in the range of 000 μm.

In the molded product, the polyvinyl chloride resin leather as the skin material and the base material made of the above mixture were firmly bonded to each other via the nonwoven fabric lined with the polyvinyl chloride resin leather.

The rib portion 8 of the formed base material is not foamed, but the flat surface portion of the base material is foamed as shown in FIG. 6, and its specific gravity is 0.60, and the specific gravity of the unfoamed sheet is 0.97. The weight was reduced by 38% compared to.

As a result of a falling ball impact test of the molded product, it was found that the above standards were met and there was no problem in impact strength. The elastic gradient of the flat surface portion of the molded product having no rib portion 8 was 46 kg / cm.

[0065]

[Fourth Embodiment] In the first embodiment, the upper die moving distance is 1.0.
The same procedure as in Example 1 was performed except that the thickness was changed to mm.

The rib portion 8 of the formed base material is not foamed, but the flat surface portion of the base material is foamed as shown in FIG. 6, and its specific gravity is 0.84, and the specific gravity of the unfoamed sheet is 0.97. Compared to, the weight was reduced by 13%.

[0067]

Example 5 In Example 1, instead of 5 parts by weight of the foaming agent of Example 1, a foaming agent [sodium hydrogen carbonate (baking soda) was used.
And polyethylene (PE) weight ratio (baking soda / PE) 3
The amount of the propylene / ethylene block copolymer of Example 1 was 68.5 parts by weight.
Further, the same procedure as in Example 1 was performed except that the temperature of the cylinder and die of the extruder was set to 190 ° C.

The specific gravity of the foamed base material of the obtained molded product was 0.
It was a white foam at 78. Also, the rib portion 8 of the molded product
The flat part having no thickness had a thickness of 3.7 mm and an elastic gradient of 30 kg / cm.

[0069]

[Comparative Example 1] The same as Example 1 except that the foaming agent of Example 1 was not used, the amount of resin charged was 650 g, and the stamping molding was performed without raising the upper die. The same was done.

The specific gravity of the base material of the obtained molded product was 0.97. Further, the flat surface portion of the molded product having no rib portion had a thickness of 3.1 mm and an elastic gradient of 29 kg / cm.

[0071]

[Comparative Example 2] The same procedure as in Example 1 was carried out except that in Example 1, the rising start timing of the upper mold was set at a pressure of 40 kg / cm ² and 10 seconds after completion of the mold clamping.

The specific gravity of the base material of the obtained molded product was 0.95, and the base material was a substantially solid unfoamed product.

[Brief description of drawings]

FIG. 1 is a view showing a state before closing upper and lower molds in a method for manufacturing a composite foam-molded article according to the present invention.

FIG. 2 is a diagram showing a state in which upper and lower molds are closed in the method for manufacturing a composite foam-molded article according to the present invention.

FIG. 3 is an enlarged view of a main part of FIG.

FIG. 4 is a view showing a foaming step of a polypropylene resin composition in the method for producing a composite foam-molded article of the present invention.

5 is an enlarged view of a main part of FIG.

FIG. 6 is a diagram showing an example of a molded product obtained by the method for producing a composite foam-molded product according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Upper mold 2 ... Lower mold 3 ... Skin material 4 ... Polypropylene resin composition 5 ... Recessed part for forming rib part of lower mold 6 ... Polypropylene resin composition Solidified layer (non-foamed layer) 7 ... Melt layer of polypropylene resin composition 8 ... Rib portion 9 ... Foamed layer 10 ... Foamed base material layer made of polypropylene resin composition

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification number Reference number within the agency FI Technical display location B29K 105: 04 B29L 9:00 4F (72) Inventor Toru Inoue Kitaohgi, Izumi-cho, Anjo City, Aichi Prefecture 4-14, Takehiro Co., Ltd.

Claims (4)

[Claims] 1. A step of setting a skin material in the vicinity of an upper die for stamping molding with a die temperature of 10 to 50 ° C., and melting at a temperature of 180 ° C. to 240 ° C. above the decomposition temperature of the foaming agent. In addition, a step of charging a base material-forming polypropylene resin composition containing a foaming agent onto the surface of a lower mold for mold stamping molding at a mold temperature of 30 to 80 ° C., and within 10 seconds after the completion of charging of the polypropylene resin composition. And closing the upper and lower molds with a pressure of 20 to 70 kg / cm ² to mold the base material shape and simultaneously integrate the base material layer made of the polypropylene resin composition and the skin material. Before the thickness of one of the solidified layers formed on both surfaces of the polypropylene resin composition layer by mold clamping reaches 1.0 mm, the polypropylene resin composition layer does not have bosses and ribs. A step of raising the upper mold within a range of 1.1 to 2 times the thickness of the surface portion to foam the polypropylene resin composition, and subsequently, cooling and solidifying the foamed base material layer made of the polypropylene resin composition. A method for producing a composite foam molded article, which comprises the steps of: 2. The decomposition temperature of the foaming agent or higher, and 180 to
A step of charging a polypropylene resin composition for forming a base material containing a foaming agent, which is melted at a temperature of 240 ° C., onto the surface of a lower mold for mold stamping molding at a mold temperature of 30 to 80 ° C., and the polypropylene resin composition. Immediately after or at the same time as the charging, the step of setting the skin material near the upper die for mold stamping molding at a mold temperature of 10 to 50 ° C., and the upper and lower metal molds within 10 seconds after the charging of the polypropylene resin composition is finished. A step of closing the mold and clamping it under a pressure of 20 to 70 kg / cm ² to shape the base material and at the same time integrate the base material layer made of the polypropylene resin composition and the skin material; Before the thickness of one of the solidified layers formed on both surfaces of the polypropylene resin composition layer reaches 1.0 mm, the boss portion and the polypropylene resin composition layer A step of raising the upper mold within a range of 1.1 to 2 times the thickness of the flat surface portion having no rib portion to foam the polypropylene resin composition, and subsequently, a foaming group made of the polypropylene resin composition. And a step of cooling and solidifying the material layer. 3. The polypropylene resin composition comprises [1]
50 to 100 parts by weight of propylene homopolymer or propylene block copolymer (A), ethylene homopolymer, α-olefin homopolymer having 4 to 10 carbon atoms,
And 0 to 50 parts by weight of the polymer (B) selected from the group consisting of copolymers between α-olefins having 2 to 10 carbon atoms [the total amount of the above components (A) and (B) is 100 parts by weight. And the melt flow rate (AST
MD 1238, L) 68 to 99.8% by weight of polypropylene resin having a range of 10 to 100 g / 10 min.
And 0.2% to 2% by weight of the foaming agent, and 0 to 30% by weight of the [3] filler. 3. The method for producing a composite foam molded article according to claim 1 or 2, wherein . 4. The foaming ratio of the foaming base material layer in the flat surface portion having no boss portion and rib portion is 1.1 to 2.0 times. Manufacturing method of composite foam molded article.