JPH06344362A - Manufacture of composite foam-molded product - Google Patents

Abstract

PURPOSE:To obtain a light-weight, highly rigid composite foam-molded product by regulating top and bottom forces to have a specified mold space with the aid of a mold space adjusting material in a very short period of time and expanding a resin composition. CONSTITUTION:A skin material A is set between a top and a bottom forces 1, 2. After keeping a specified space between the forces, a polypropylene resin composition containing a foaming agent, which has been melted at a predetermined temperature, is introduced into a space between the bottom force 2 and the skin material, 8. At the same time, the top force 1 is lowered down at a predetermined speed to clamp the forces until the forces have a predetermined space, and a base material layer, which has not yet been expanded, is integrated with the skin material 8 simultaneously with the shaping of a base material shape. In a period of 0.5 to 5 seconds, the top force 1 is elevated, and it is then lowered until a space L3 between the top and bottom forces 1, 2 is within a range satisfying a formula -t2+t3X1.1<=L3<=t2+t3X2.0-with the aid of a mold space adjusting material 20' to expand the polypropylene resin composition. Thus, a foamed base material layer 14 composed of the polypropylene resin composition is cooled and hardened under the pressurized condition while the mold space adjusting material 20' is being kept in a set state.

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 that 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 for automobile interior materials as described above is usually composed mainly of polypropylene and has a filler of 15 to 30 for the purpose of improving the rigidity, heat resistance and dimensional stability of the base material.
The composition is added in an amount of about wt%.

Talc is usually used as the filler. The specific gravity of talc is 2.6, which is larger than the specific gravity of polypropylene which is 0.91. Therefore, the specific gravity of the mixture of both often exceeds 1.0. Polypropylene is one of the lightest resins among resins, but has a problem that it is heavy as a base resin.

[0005] Today, weight reduction of automobiles has become an important theme for improving fuel efficiency of vehicles and environmental problems. Therefore, weight reduction of automobile interior materials has become an important theme. For the above-mentioned filler-containing polypropylene, the weight reduction has been studied by improving the rigidity by super-crystallization of polypropylene. Since such ultra-highly crystallized polypropylene has a large specific gravity, it is necessary to reduce the thickness of the base material in order to reduce the weight. As a result, there is a problem that the rigidity of the whole base material is lowered.

By the way, in Japanese Patent Laid-Open No. 4-144721, a polypropylene resin containing a non-foamed skin layer and a foamed core layer is formed by a press molding method using a polypropylene resin mixed with a chemical foaming agent. A method for molding a foam molded article and a method for molding a polypropylene resin foam molded article composed of a skin material, a skin layer which has not been foamed, and a core layer which is foamed are described. According to the examples, the expansion ratio of the core layer of the foamed molded product obtained by this molding method is as low as 1.20 to 1.25.

Further, Japanese Patent Laid-Open No. 148907/1992 describes a method for molding a polypropylene resin molded body in which a skin material having a foamed layer is laminated. This molding method is a press molding method in which a polypropylene resin mixed with a chemical foaming agent is used to form a polypropylene resin foamed product including a skin material with a foamed layer backing, an unfoamed skin layer and a foamed core layer. Obtain a molded body. According to the examples, the expansion ratio of the core layer of the foamed molded product obtained by this molding method is as low as 1.2 to 1.3 times.

Therefore, it has been desired to develop a method capable of producing a composite foam molded article which is lighter in weight and higher in rigidity than the foam molded article described in the above publication, by the mold stamping molding method. There is.

[0009]

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.

[0010]

SUMMARY OF THE INVENTION A method for manufacturing a composite foam molded article according to the present invention comprises: [I] a step of setting a skin material between upper and lower molds for mold stamping molding which are slidable at a meshing portion in an open state; II] The upper and lower mold spacing L ₁ (mm) is represented by the following formula (t ₁ +5) ≦ L ₁ ≦ (t ₁ +30) [t ₁ represents the thickness (mm) of the skin material before applying pressure] The content of the 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 the same time as injecting it between the lower mold and the skin material using the mold gap adjusting material.
₂ (mm) is the following formula: L ₂ = t ₂ + t ₃ [t ₂ represents the thickness of the skin material after pressure is applied, and t ₃
Represents the thickness of the flat surface of the foamable resin base material excluding the boss and the rib].
a step of lowering at a speed of mm / sec and clamping to mold the base material shape and at the same time integrate the unfoamed base material layer made of the polypropylene resin composition and the skin material, [III] the base The upper die is lifted within 0.5 to 5 seconds after the shaping of the material shape is completed, and the die gap adjusting material is used to form the upper and lower die gaps L _3.
And a step of foaming the polypropylene resin composition by lowering the upper mold until (mm) is within a range satisfying the following formula: t ₂ + t ₃ × 1.1 ≦ L ₃ ≦ t ₂ + t ₃ × 2.0. And [IV] after the foaming of the polypropylene resin composition is completed, a step of cooling and solidifying a foaming base material layer made of the polypropylene resin composition in a pressurized state with the mold interval adjusting material set. I am trying.

[0011]

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 the 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 at least a polypropylene resin (A) and a foaming agent (C). In addition to these components, this composition may contain a propylene / α-olefin copolymer (B) and / or a filler (D).

The polypropylene resin (A) used in the present invention is a resin comprising a propylene homopolymer or a propylene block copolymer, and has a melt flow rate (ASTM D 1238, 230 ° C., load 2.16 k).
g) is usually 10 to 100 g / 10 minutes, preferably 20 to
Within the range of 60 g / 10 minutes.

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 (A) be within the above range.

Further, propylene / α used in the present invention
-The olefin copolymer (B) is a copolymer composed of propylene and ethylene or an α-olefin having 4 to 10 carbon atoms.

Specific examples of the α-olefin having 4 to 10 carbon atoms include butene-1, pentene-1, 4
-Methylpentene-1, hexene-1, heptene-1,
Examples include octene-1, nonene-1, decene-1 and the like.

Specific examples of the propylene / α-olefin copolymer (B) include ethylene / propylene copolymer rubber (EPR), ethylene / butene-1 copolymer rubber (EBR) and propylene / ethylene. Copolymer rubber (PER), Propylene / Butene-1 copolymer rubber (P
BR) and the like. However, the copolymer here does not include a propylene block copolymer.

The melt flow rate of such a propylene / α-olefin copolymer (B) (ASTM D 12
38, 230 ℃, load 2.16kg) is usually 0.1
It is in the range of 100 g / 10 minutes, preferably 1 to 50 g / 10 minutes.

In the present invention, in order to form bosses and ribs at a pressure as low as possible, it is desirable that the melt flow rate of the propylene / α-olefin copolymer (B) is within the above range.

As the foaming agent (C) used in the present invention, specifically, azodicarbonamide (ADCA),
N, N'-dinitrosopentamethylenetetramine, 4,
4'-oxybis (benzenesulfonyl hydrazide),
Examples thereof include organic foaming agents such as diphenylsulfone-3,3′-disulfonylhydrazide, p-toluenesulfonyl semicarbazide, and trihydrazinotriazine, and inorganic foaming agents such as sodium hydrogen carbonate, sodium carbonate, ammonium hydrogen carbonate, and ammonium carbonate. Among them, azodicarbonamide (ADCA) and sodium hydrogen carbonate are particularly preferable.

The above-mentioned foaming agent (C) may be directly added to the above-mentioned polypropylene resin (A) or filler (D) described later, but there are many problems in the dispersibility of the foaming agent. A master-batch in which polypropylene or polyethylene is mixed with the foaming agent (C) at a high concentration is preferably used.

Specific examples of the filler (D) used in the present invention include talc, calcium carbonate, barium sulfate, silica, glass fibers, carbon fibers and whiskers. In the present invention, from the viewpoint of improving foamability,
Glass fiber and talc are particularly suitable.

When the filler as described above is used in a ratio as described below, the resulting composite foam molded article has improved rigidity and heat resistance and improved dimensional stability (reduction in shrinkage rate, reduction in linear expansion coefficient). In the present invention, it is preferable to use the above-mentioned fillers because they have the effect of

The polypropylene resin composition for forming a base material used in the present invention comprises a polypropylene resin (A) and a propylene / α-olefin copolymer (B) 100-70.
Parts by weight, preferably 90 to 70 parts by weight, and a blowing agent (C)
0.5 to 5 parts by weight, preferably 1 to 3 parts by weight, and a filler (D) 0 to 30 parts by weight, preferably 10 to 30 parts by weight, and a polypropylene resin (A) and propylene / α-. The weight ratio [(A) / (B)] with the olefin copolymer (B) is 100/0 to 70/30, preferably 100/0 to 80/20.

Skin Material The skin material used in the present invention is specifically (1)
A material that can be bonded to a polyolefin material by an anchor effect or a fastener effect, that is, a surface porous material, for example, a fibrous material such as nonwoven fabric, cloth, or fabric, (2) a leather that can be fused with a polyolefin material, for example, an olefin thermoplastic Elastomer (TPO) leather, (3)
Polyurethane (PU), polyvinyl chloride resin (PV
C), a two-layer laminate in which a olefin thermoplastic elastomer (TPO) leather and a backing material made of the above surface porous material are laminated, (4) the above leather, and resin foam Body, for example, a two-layer laminate in which polypropylene foam, polyurethane foam, polyvinyl chloride resin foam, etc. are laminated, (5) the above surface porous material, the resin foam, and the resin film or A three-layer laminate in which a backing material composed of sheets is sequentially laminated, (6) Leather capable of being fused with the above-mentioned polyolefin-based material, and resin foam capable of being fused with the above-mentioned polyolefin-based material And a three-layer laminate in which the above-mentioned surface porous material or polyolefin-based material and a backing material made of a resin film or sheet that can be fused with each other are sequentially laminated. It is.

In the present invention, a three-layer laminate comprising a non-woven fabric, a cloth, a fabric or a laser, a polypropylene foam, and a polyolefin resin film or sheet having a thickness of 0.05 to 0.5 mm is preferable. Used. In this polyolefin resin film, the polypropylene foam forming the intermediate layer of the three-layer laminate is
This polypropylene-based foam is protected so as not to be adversely affected by heat and pressure when integrally molding the unfoamed base material layer and the skin material.

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. A mold stamping molding apparatus is used for manufacturing the composite foam molded article according to the present invention.
In the present invention, for example, a mold stamping molding device that combines an injection molding machine and a vertical press is preferably used. The press needs to be able to raise and lower the upper mold at a predetermined position and at a predetermined time.

FIG. 1 is an example of a mold used in the present invention and is a schematic vertical sectional view thereof. The mold used in the present invention comprises an upper mold 1 and a lower mold 2. The upper mold 1 and the lower mold 2 are fixed to an upper platen 3 and a lower platen 4, respectively. It is slidable at the meshing portion 5 between the lower die 2 and the lower die 2. Further, the lower mold 2 is provided with a gate 7 communicating with a cavity 6 formed by the upper and lower molds 1 and 2. Although only one gate 7 is shown in FIG. 1, a plurality of gates 7 are usually provided. Figure 1
Although not shown, cooling pipes are provided inside the upper mold 1 and the lower mold 2. Further, when forming a boss portion or a rib portion on the base material layer of the composite foam molded article, a lower mold having a boss portion or a rib portion forming recess on the surface is used.

First, as shown in FIG. 2, the skin material 8 is set between the upper and lower molds 1 and 2 for mold stamping molding which are slidable at the meshing portion 5 in the open state. Skin material 8
Is usually set between the upper mold 1 and the lower mold 2,
It is also possible to set the skin material on the upper mold 1 or the lower mold 2 surface. The above skin material can be integrated with the unfoamed base material layer at the same time as shaping the base material by stamping molding. However, when a skin material having a foam layer is used, when molding a composite foam molded article. In order to prevent the foam layer from getting settled, it is preferable to employ the following method. (1) A skin material having a foam layer is vacuum-molded in advance using a vacuum forming mold having the same shape as the mold stamping molding upper mold, and the vacuum-molded skin material is used as a mold stamping molding upper mold. How to set. (2) The skin material having a foam layer is vacuum-formed by a vacuum forming device provided in the upper die for mold stamping molding, and the next step is performed while keeping the vacuum-formed skin material in contact with the upper die. How to get in.

In the present invention, since the upper die 1 is applied with pressure on the skin material 8 later, the die temperature of the upper die 1 is 10 to 50 ° C. in order not to damage the skin material 8. , Preferably 10 to 30 ° C.

Next, as shown in FIG. 3, the upper and lower mold intervals L ₁ (mm) are calculated by the following formula (t ₁ +5) ≦ L ₁ ≦ (t ₁ +30) [t ₁ is the skin material before applying pressure] Of the resin raw material 9 melted at the decomposition temperature of the foaming agent or higher and at a temperature of 180 to 240 ° C., that is, for forming a base material containing the foaming agent. At the same time as injecting the polypropylene resin composition from the gate 7 provided in the lower mold 2 into the cavity 6, that is, between the lower mold 2 and the skin material 8, as shown in FIG. Material 20
Is used to calculate the distance L ₂ (mm) between the upper and lower dies by the following formula: L ₂ = t ₂ + t ₃ [t ₂ represents the thickness of the skin material after pressure is applied, and t ₃
Represents the thickness of the foamable resin substrate flat surface portion excluding the boss portion and the rib portion].
The unfoamed base material layer 10 made of a polypropylene resin composition and the skin material 8 are integrated at the same time as shaping the base material shape and lowering the mold at a speed of 0 mm / second, preferably 1 to 10 mm / second. To do.

The above-mentioned polypropylene resin composition for forming a base material is the above-mentioned polypropylene resin (A), foaming agent (C), further filler (D), and propylene / α-olefin copolymer before the injection. (B) is prepared by uniformly mixing the above-mentioned proportions with a mixing and stirring device such as a Henschel mixer.

The polypropylene resin composition is melted at the above temperature by using an injection molding machine provided in the mold stamping molding machine. When the polypropylene resin composition is melted, the foaming agent decomposes and begins to foam, so if the polypropylene resin composition is melted at the above temperature, immediately inject this polypropylene resin composition between the lower mold and the skin material. To do.

After the upper and lower mold gap L ₁ is set in the above range, the polypropylene resin composition is injected between the lower mold and the skin material while performing mold clamping, and the injected polypropylene resin composition Can be kept in a pressurized state, so that the polypropylene resin composition can be prevented from foaming until the polypropylene resin composition is shaped into a predetermined substrate shape.

The mold gap adjusting material is specifically a spacer such as a spacer block. However, since it can be mechanically positioned, it is more accurate than the hydraulic system.

By maintaining the upper and lower mold gaps L ₂ constant by using the mold gap adjusting material as described above, a composite consisting of a skin material and an unfoamed base material layer at the end of shaping of the base material shape. Prevents excessive pressure from being applied to.

As described above, since the lower mold 2 and the molten polypropylene resin composition are in direct contact with each other, if the mold temperature of the lower mold 2 is too low, the injected polypropylene resin composition is cooled rapidly. This will lead to 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 10 to 80 ° C., preferably 30 to 6
It is 0 ° C.

At the end of the mold clamping, in the unfoamed base material layer 10 constituting the obtained composite, as shown in FIG. 5, solidified layers 11 are formed on both surfaces of the unfoamed base material layer 10, and The central portion of the foam base material layer 10 is a molten layer 12 of the polypropylene resin composition. The solidified layer 11 is formed by
The upper and lower molds are lower in temperature than the molten polypropylene resin composition.

Then, as shown in FIG. 6, the upper die 1 is raised within 0.5 to 5 seconds after the shaping of the base material is completed, and the upper and lower portions are moved up and down by using the die gap adjusting material 20 '. Mold spacing L ₃
(Mm) is the following formula: t ₂ + t ₃ × 1.1 ≦ L ₃ ≦ t ₂ + t ₃ × 2.0 [t ₂ represents the thickness of the skin material after pressure is applied, and t ₃
Represents the thickness of the expandable resin base material flat surface portion excluding the boss portion and the rib portion], and the upper mold 1 is lowered until the polypropylene resin composition is foamed.

The degree of foaming of the polypropylene resin composition can be controlled by the interval L ₃ between the upper and lower molds. Since the upper and lower mold gap L ₃ is set by using the mold gap adjusting material, the mold gap can be set with high accuracy.

Foaming occurs in the molten layer 12 of the polypropylene resin composition shown in FIG. 5, as shown in FIG.
It does not occur in the solidified layer 11. That is, by such foaming, the foam base material layer 1 including the solidified layer 11 and the foam layer 13
4 is formed.

Further, the foamed base material layer 14 shown in FIG. 6 has neither a boss portion nor a rib portion, but in the present invention, even if a foamed base material layer having a boss portion or a rib portion is formed. The polypropylene resin composition of the boss and the rib does not foam.

Next, after the foaming of the polypropylene resin composition is completed, the foaming base material layer 14 made of the polypropylene resin composition is cooled and solidified under pressure while the mold gap adjusting material 20 'is set.

The temperature of the lower mold when the foamed base material layer 14 is cooled and solidified is 10 to 80 ° C., preferably 30 to 80 ° C.
It is 60 ° C., and the temperature of the upper mold is 10 to 80 ° C., preferably 10 to 50 ° C. The upper and lower mold temperatures are adjusted by introducing water or oil having a predetermined temperature into a cooling pipe provided inside the upper and lower molds.

Finally, the upper die 1 is raised, the molded body shown in FIG. 6 is taken out and trimmed, and as shown in FIG.
A composite foam molded article is obtained, which is composed of the foam base material layer 14 formed of the solidified layer 11 and the foam layer 13 and the skin material 8.

In the above-mentioned manufacturing method, as the skin material, for example, a three-layer laminated body formed of olefinic thermoplastic leather, polypropylene foam, and a backing material such as nonwoven fabric is used, and has a rib portion forming recess. If the lower mold is used, a composite foam molded article as shown in FIG. 8 can be obtained. This composite foam molded article comprises a skin material 8 and a foam base material layer 14 having a rib portion 15, and the skin material 8 is
The olefin-based thermoplastic leather layer 16, the polypropylene foam layer 17, and the backing material layer 18 are formed, and the foam base material layer 14 includes the solidified layer 11 and the foam layer 1.
3 and 3.

The composite foam-molded article manufactured through the above steps has a foaming ratio of 1.1 to 2.0 times in the flat portion having no rib portion or boss portion of the foaming base material layer. Thus, according to the present invention, a composite foam molded article having a foaming base material layer having a high expansion ratio of 2.0 times can be obtained.

[0048]

EFFECTS OF THE INVENTION According to the present invention, it is possible to obtain a composite foam molded product which is low in cost and lightweight and has high rigidity as compared with the composite foam molded product manufactured by the conventional mold stamping molding method.

The composite foamed molded article can be used for applications requiring particularly light weight, for example, 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 of the falling ball impact test and the bending test are as follows. (1) Bending test The bending test is 3 specified in ASTM D 790.
Maximum bending load (unit: N)
And an elastic gradient (a value obtained by dividing the bending load within the elastic limit by the amount of deformation, unit: N / m), which is an index of bending rigidity, were obtained. However, the size of the test piece is 50 mm in width and 150 mm in length, the distance between spans is 100 mm, and the bending speed is 50 mm / min. (2) Falling ball impact test In the falling ball impact test, a falling ball impact strength (unit: N · m) was obtained by dropping 500 g of a steel ball on the surface of a foamed substrate. However, the test temperature is 0 ° C.

[0051]

[Example 1] [Preparation of skin material] A 0.6 mm-thick olefin thermoplastic elastomer laser and a 3.0 mm-thick polypropylene foam having an expansion ratio of 25 times [manufactured by Toray Industries, Inc., trade name To- Lepefu PPAM25030] and a thickness of 0.2 mm
The above olefinic thermoplastic elastomer sheet (backing sheet) was laminated by heat fusion to obtain a three-layer laminate.

Then, the obtained three-layer laminate was vacuum-formed by a skin vacuum forming machine [Fuse Vacuum Co., Ltd., vacuum / pneumatic forming machine] using a door trim skin forming die to form a door trim. A skin material was obtained.

[Preparation of polypropylene resin composition for forming base material] Propylene block copolymer [Rubber component content:
10% by weight, ethylene content: 20 mol%, MFR (A
STM D 1238, 230 ° C, 2.16 kg): 4
5 g / 10 min, density (ASTM D 1505): 0.
91 g / cm ³ ] 70 parts by weight, and a propylene / butene copolymer [propylene content: 70 mol%, MFR (AST
MD 1238, 190 ° C, 2.16 kg): 3.2
g / 10 minutes, density (ASTM D 1505): 0.8
9 g / 10 minutes] 10 parts by weight and 20 parts by weight of talc having an average particle size of 3 μm as a filler were mixed in a Henschel mixer, and the resulting mixture was mixed with a twin-screw extruder for 21
It was melted at 0 ° C. to give pellets.

Then, 100 parts by weight of the pellets were blended with 70% by weight of a propylene block copolymer having the same properties as the above propylene block copolymer and 30% by weight of azodicarbonamide (ADCA), and pelletized. 4 parts by weight of the obtained unfoamed master batch was added to obtain a polypropylene resin composition for forming a substrate.

[Preparation of Composite Foam Molded Article] First, in a mold stamping molding apparatus in which an injection molding machine [clamping force 850 tons, injection capacity 4500 cm ³ ] and a vertical press [pressing capacity 800 tons] are combined, a meshing portion is formed. Upper and lower door trim molding dies that can be slid on (mold area 0.
65 m ² ), the above-mentioned skin material (planar portion thickness 3.8 mm) obtained by vacuum forming in advance was fixed to the upper mold in the open upper and lower molds. The lower mold is provided with a rib portion forming recess.

Then, the space between the upper and lower dies (L ₁ ) is set to 15 mm.
After that, the polypropylene resin composition for forming a base material is melted and plasticized at 200 ° C. by an injection molding machine, and injection is started between the skin material and the lower mold through a gate provided in the lower mold. did. Simultaneously with the start of resin injection, the upper mold is 5 mm /
It started to descend at a speed of 2 seconds, and 1 second after the completion of the resin injection, the mold clamping was completed to finish the shaping of the base material-forming polypropylene resin composition. The resin injection time was 3 seconds.
The space between the flat parts of the upper and lower molds (L
₂ ) is 3.0 mm [skin material 1.0 mm (skin layer 0.6
mm + form layer 0.2 mm + backing layer 0.2 m
m) + base material layer 2.0 mm], and the die interval (L
₂ ) regulated by setting a spacer having a thickness of 3.0 mm on the zero-touch portion outside the molding surface of the mold, that is, on the lower platen surface indicated by reference numeral 19 in FIG.
At the end of this mold clamping, the skin material and the base material layer made of the polypropylene resin composition for forming the base material were integrated by heat fusion. Further, since this base material layer was shaped under pressure, it was in a non-foamed state.

Then, 1 second after the end of the shaping of the above base material shape, the upper die is lifted and the upper and lower die intervals (L ₃ ) are accurately 4.2 mm (1.0 + 2.0 × 1.1). ≦ L ₃ ≦ 1.0 +
Polypropylene for forming a base material in which a spacer having a thickness of 4.2 mm is set to the zero touch portion and the upper mold is lowered to form a base material layer so that the thickness becomes 2.0 × 2.0 [mm]). The resin composition was foamed to form a foamed base material layer.

After completion of the foaming, the foamed base material layer was cooled and solidified under pressure while the spacer was set. Cooling is performed by circulating oil of 50 ° C. through a cooling pipe provided in the lower mold and flowing water through a cooling pipe provided in the upper mold to bring the upper mold temperature to 20 ° C. It was carried out at 40 ° C. for 40 seconds.

Then, the composite foam molded article obtained as described above was taken out by opening the upper and lower molds. The state of the foam cells in the foam base material layer of this composite foam molded article was examined, and the maximum bending load, elastic gradient and falling ball impact strength were determined by the above-mentioned methods.

The results are shown in Table 1. Furthermore, when the cross-sectional state was examined by cutting the flat surface portion of this composite foam molded article that did not include the rib portion, the thickness of the foam base material layer was 3.1 mm.
The solidified layers formed on both surfaces of the foamed base material layer were good and both had a thickness of 0.4 mm. The foam layer constituting the foam base material layer had a thickness of 2.3 mm, and the diameter of the foam cell formed of the foam layer was about 300 μm and uniform. The specific gravity of the foam substrate layer was 0.65.

When the thickness of the polypropylene foam layer was examined by cutting the skin material of the composite foam molded article, the thickness before molding was 3.0 mm, while the thickness after molding was 2.3 mm. However, the skin material had a cushioning feeling and kept a thickness that could withstand practical use.

As is clear from Table 1, the foamed base material layer of Example 1 was significantly improved in bending rigidity as compared with the non-foamed base material layer of Comparative Example 1 described later.

[0063]

Comparative Example 1 In Example 1, the polypropylene resin composition for forming a base material was injected between the skin material and the lower mold, and at the same time, the upper mold was lowered to set the mold interval (L ₂ ) to 3. 0m
After closing the upper and lower molds to m and maintaining the mold interval (L ₂ ) of 3.0 mm for 45 seconds even after the shaping of the substrate shape,
The same procedure as in Example 1 was performed except that the upper and lower molds were opened and the composite molded product was taken out.

When the cross-sectional state of the base material layer of the composite molded article obtained as described above was examined, the base material layer had a thickness of 2.0.
mm, the specific gravity was 1.0, and no foaming occurred.
Further, the maximum bending load, the elastic gradient and the falling ball impact strength of the base material layer of this composite molded article were determined by the above methods.

The results are shown in Table 1. As described above, this non-foamed base material layer was inferior in flexural rigidity to the foamed base material layer of Example 1.

[0066]

[Comparative Example 2] In Example 1, the polypropylene resin composition for forming a base material was formed 10 seconds after the upper and lower molds were closed and the shaping of the base material was completed, with an upper and lower mold gap (L ₃ ) of 4.2 mm. A composite foam molded article was obtained in the same manner as in Example 1 except that the product was foamed.

The foamed base material layer of the obtained composite foamed molded product had a small thickness of 2.3 mm, and the solidified layers formed on both surfaces of this foamed base material layer had a thickness of 1.1 mm. The center of the layer was slightly foamed, and the specific gravity of the foamed base material layer was 0.87.

[0068]

[Comparative Example 3] In Example 1, when the polypropylene resin composition for forming a substrate was poured from the gate provided in the lower mold, the upper mold was fixed without being lowered, and then the injection was completed. Example 1 except that the mold was closed and shaped
It carried out similarly to.

The maximum bending load, elastic gradient and falling ball impact strength of the foamed base material layer of this composite foamed molded product were determined by the above-mentioned methods. The results are shown in Table 1.

Further, when the cross-sectional state of the foamed base material layer of the obtained composite foam molded article was examined, the foamed cells of the foamed base layer constituting the foamed base material layer were flattened according to the flow state of the resin. In addition, the solidified layer formed on both sides of the foam layer,
It contained bubbles and was not a good solidified layer.

As is apparent from Table 1, the falling ball impact strength of the foamed base material layer of the obtained composite foamed molded product was 1.2 N /
m and the impact strength of the composite foam molded article of Example 1 7.5 N / m
It was much worse.

In the polypropylene foam layer forming the skin layer, the collapse of the foam cells around the gate was found in Example 1.
Compared with the above, the foam layer of the skin was significantly damaged.

[0073]

[Comparative Example 4] In Example 1, 1 second after the shaping of the substrate shape was completed, the upper and lower mold intervals (L ₃ ) were changed to 5.4 m.
A composite foam molded article was obtained in the same manner as in Example 1 except that m (t ₂ + t ₃ × 2.2) was used.

When the state of the foam base material layer of the obtained composite foam molded article was examined, the thickness of the foam base material layer was 3.8 mm, but the foam cells in the foam layer constituting the foam base material layer were Coarse air bubbles were formed, and some open air bubbles were also seen. In addition, the overall shape of the composite foamed product was wavy and deformed, and the product was not practical.

[0075]

[Example 2] In the preparation of the skin material of Example 1, a 0.6 mm-thick olefin thermoplastic elastomer laser and a 3 mm-thick polypropylene foam having a foaming ratio of 15 times [trade name, manufactured by Toray Industries, Inc. -Lepev PPSM150
30] was used in the same manner as in Example 1 to prepare a two-layer laminate skin material.

Hereinafter, a composite molded article was obtained in the same manner as in Example 1 except that this skin material was used instead of the skin material of Example 1.

[0077]

[Table 1]

[Brief description of drawings]

FIG. 1 is an example of a mold used in the present invention, which is a schematic vertical sectional view thereof.

FIG. 2 is a diagram showing a state in which a skin material is set in an upper mold for mold stamping molding.

FIG. 3 is a view showing a state in which a resin raw material (polypropylene resin composition for forming a base material) is injected between a skin material and a lower mold at a predetermined upper and lower mold gap L ₁ .

FIG. 4 is a view showing a state where the molds are clamped at a predetermined upper and lower mold gap L ₂ .

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

FIG. 6 is a view showing a state in which a resin raw material is foamed at a predetermined upper and lower mold gap L ₃ .

FIG. 7 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.

FIG. 8 is a diagram showing an example of a molded product having a rib portion obtained by the method for producing a composite foam molded product according to the present invention.

[Explanation of symbols]

1 ・ ・ ・ ・ Upper mold 2 ・ ・ ・ ・ Lower mold 3 ・ ・ ・ ・ Upper platen 4 ・ ・ ・ ・ Lower platen 5 ・ ・ ・ ・ Interlocking part 6 ・ ・ ・ ・ Cavity 7 ・ ・ ・ ・ Gate 8 ... Skin material 9 ... Resin raw material (polypropylene resin composition for base material formation) 10 ... Unfoamed base material layer 11 ... Solidification layer 12 ... Melting layer 13 ...・ ・ ・ Foam layer 14 ・ ・ ・ Foam base layer 15 ・ ・ ・ Rib part 16 ・ ・ ・ Olefin thermoplastic thermoplastic leather layer 17 ・ ・ ・ Polypropylene foam layer 18 ・ ・ ・ Backing material layer 19 ・ ・ ・ ・ Zero touch part 20 ・ ・ ・ ・ Mold spacing adjusting material (spacer block) 20 '・ ・ ・ Mold spacing adjusting material (spacer block) L ₁ , L ₂ , L ₃・ ・ ・ Vertical die spacing

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Claims (3)

[Claims] 1. A step of [I] setting a skin material between upper and lower molds for mold stamping molding which is slidable at an engaging portion in an opened state, and [II] a gap L ₁ (mm) between upper and lower molds.
After the temperature is within the range represented by the following equation (t ₁ +5) ≦ L ₁ ≦ (t ₁ +30) [t ₁ represents the thickness (mm) of the skin material before applying pressure] And the polypropylene resin composition for forming a base material containing a foaming agent, which is melted at a temperature of 180 to 240 ° C., is injected from a gate provided in the lower mold between the lower mold and the skin material. At the same time, using the mold gap adjustment material, the upper and lower mold gap L
₂ (mm) is the following formula: L ₂ = t ₂ + t ₃ [t ₂ represents the thickness of the skin material after pressure is applied, and t ₃
Represents the thickness of the flat surface of the foamable resin base material excluding the boss and the rib].
a step of lowering at a speed of mm / sec and clamping to mold the base material shape and at the same time integrate the unfoamed base material layer made of the polypropylene resin composition and the skin material, [III] the base The upper die is lifted within 0.5 to 5 seconds after the shaping of the material shape is completed, and the die gap adjusting material is used to form the upper and lower die gaps L _3.
And a step of foaming the polypropylene resin composition by lowering the upper mold until (mm) is within a range satisfying the following formula: t ₂ + t ₃ × 1.1 ≦ L ₃ ≦ t ₂ + t ₃ × 2.0. And [IV] after the foaming of the polypropylene resin composition is completed, a step of cooling and solidifying a foaming base material layer made of the polypropylene resin composition in a pressurized state with the mold interval adjusting material set. And a method for producing a composite foam molded article. 2. The skin material is a three-layer laminate comprising a non-woven fabric, a cloth, a fabric or a laser, a polypropylene foam, and a polyolefin resin film or sheet. 1. The method for producing a composite foam molded article according to 1. 3. The polypropylene resin composition for forming a base material comprises a polypropylene resin (A) and 100 to 70 parts by weight of a propylene / α-olefin copolymer (B), and a blowing agent (C) of 0.5 to 5 Parts by weight and 0 to 30 parts by weight of the filler (D), and the weight ratio [(A) / (B)] of the polypropylene resin (A) and the propylene / α-olefin copolymer (B) is 10
It is 0 / 0-70 / 30, The manufacturing method of the composite foam-molded article of Claim 1 or 2 characterized by the above-mentioned.