JPH06891A - Production of polypropylene resin in-mold foamed molded object having skin - Google Patents

Abstract

PURPOSE:To strongly integrate a skin material and in-mold foam simultaneously with the production of the in-mold foam from prefoamed particles even when the skin material has no air permeability and the thickness of a foam layer is large and to prevent the generation of welding inferiority. CONSTITUTION:A steam impermeable skin material 8 is provided to the inner surface of a mold A1 and the mold A1 and a mold B2 are clamped to constitute a mold which is, in turn, filled with polypropylene resin prefoamed particles and steam is supplied only from the steam orifices 4 of the mold B2 without heating the mold A1 and the prefoamed particles are preheated at temp. lower than temp. mutually welding the prefoamed particles to be wetted with steam and finally heated at temp. equal to or higher than the temp. mutually welding the prefoamed particles.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a polypropylene resin in-mold foam molded article having a skin. More specifically, it relates to a method for producing a polypropylene resin in-mold foam molded article having a skin that can be suitably used, for example, as an interior material for automobiles.

[0002]

2. Description of the Related Art Conventionally, in a polypropylene resin in-mold foam molded article provided with a skin material, the in-mold foam body is prepared in advance, and an adhesive is applied to it, for example.
Then, it is manufactured by a method of attaching a skin material. However, according to such a method, three steps are required: a step of producing an in-mold foam, a step of applying an adhesive, and a step of attaching a skin material to the in-mold foam.
There are drawbacks that the manufacturing process is complicated and the production efficiency is not good.

As a method capable of eliminating the drawbacks of the above method,
After providing a porous sheet having air permeability on at least the steam hole surface of a pair of molds having a plurality of steam holes, the thermoplastic resin foam particles are filled, and then steam is introduced from the steam holes to form a porous sheet. Further, a method for producing an in-mold foamed molded body, in which foamed particles are heat-fused and integrated, is known (Japanese Patent Application Laid-Open No. Hei 10 (1999) -242242).
3-190723 publication).

The method for producing the in-mold foam molded article is effective when the skin material is a porous sheet, but when the skin material is a resin sheet having no air permeability, etc. , The steam introduced from the steam holes is blocked by the resin sheet and does not reach the expanded particles, so that the expanded particles are not sufficiently heated, causing poor fusion, and the mechanical properties of the obtained molded body are There is a problem that it is inferior to the one in which the skin material is fused to the in-mold foam with an adhesive.

[0005]

Therefore, in view of the above-mentioned prior art, the inventors of the present invention have manufactured the in-mold foam from the pre-expanded particles at the same time, even if the skin material has no air permeability. As a result of earnest studies to obtain a polypropylene resin in-mold foam molded product having a skin that the skin material and the in-mold foam can be integrated, and that the in-mold foam does not have defective fusion. When the polypropylene resin pre-expanded particles are used without heating one mold at all, and the pre-expanded particles are heated and expanded under special conditions, the thickness of the foam layer is large. However, the inventors finally found that an in-mold foam molded article having a skin that did not cause defective fusion was produced, and completed the present invention.

[0006]

That is, according to the present invention, a skin material which is impermeable to steam is provided on the inner surface of the mold A, and the mold A
After the mold and the mold B are clamped together to form a mold, polypropylene-based resin pre-expanded particles are filled in the mold and steam is generated only from the steam holes of the mold B without heating the mold A. Supplied, preheat the pre-expanded particles at a temperature lower than the temperature at which the pre-expanded particles are fused to each other, steam the pre-expanded particles with steam, and then the temperature at which the pre-expanded particles are fused to each other The present invention relates to a method for producing a polypropylene-based resin in-mold expansion-molded article having a skin, which comprises mainly heating the pre-expanded particles at the temperature of.

[0007]

OPERATIONS AND EXAMPLES In the method for producing a polypropylene resin in-mold foam molded article of the present invention, in order to eliminate defective fusion between pre-expanded particles, the pre-expanded particles are steamed from both sides in the mold. It is intended to provide an in-mold foamed molded product by completely heating one side of a completely new molding mold that breaks the conventional wisdom that must be heated.

According to the method for producing an in-mold foamed molded product of the present invention, the reason why an in-mold foamed molded product without defective fusion between particles can be manufactured, but it is not known. In addition to the heating by the pre-heating under specific conditions, the process of steaming is performed, so the pre-expanded particles on the side where the steam of the mold is introduced and the pre-foaming on the skin side It can be inferred that this is because the temperature difference between the particles becomes small and the fusion property due to the main heating is improved.

An embodiment of a method for producing a polypropylene resin in-mold foamed article having a skin according to the present invention will be described below with reference to the drawings.

FIG. 1 is a schematic explanatory view showing one embodiment of a molding die used in the manufacturing method of the present invention.

In FIG. 1, the mold A1 is clamped to the mold B2. In FIG. 1, the mold A1 has no steam holes, but in the present invention, the steam holes may be provided because there is no particular problem. The mold A1 is, for example, a cylinder 3
And the like, and is configured to be able to clamp and open the mold A1 and the mold B2 by moving the mold A1. A plurality of steam holes 4 are provided on the inner surface of the mold B2, and the steam introduced from the steam inlet 5 passes through the steam holes 4 through the inside 6 of the mold B2 into the molding chamber 7. be introduced. A feeder 9 is provided in the mold B2, and the polypropylene 9 pre-expanded particles as a raw material are introduced into the molding chamber 7 by the feeder 9.

In the method for producing an in-mold foam molded article of the present invention, the pre-expanded particles are not heated by steam from the mold A1.

First, a skin material 8 is provided on the inner surface of the mold A1. In the present invention, as the skin material, a material having substantially no air permeability is used, but a material having air permeability may be used.

Examples of the skin material 8 include a resin sheet and a laminated sheet of a resin sheet and a polyolefin resin extruded foam sheet. Specific examples of such polyolefin resin include polypropylene,
Examples include polyethylene, ethylene-propylene copolymer, chlorinated polypropylene, chlorinated polyethylene, ethylene-propylene-butene terpolymer, and mixtures thereof, but the present invention is not limited to these examples.

Specific examples of the resin sheet include a vinyl chloride resin sheet, a resin sheet made of a polyolefin resin such as a polypropylene resin and a polyethylene resin, and the like, but the present invention is limited to such a resin sheet. It is not something that will be done. Since such a resin sheet is used as a skin of the obtained in-mold foam molded article, it may be colored in a desired color, and is textured to impart a high-class feeling. In addition, a woven fabric, a non-woven fabric, a web or the like may be appropriately formed in order to impart a soft texture to the surface.

The skin material 8 may be preliminarily formed into a desired shape by, for example, vacuum forming in order to be adapted to the shape of the inner surface of the mold A1, but it is flexible. In the case of a product, a sheet-shaped product may be inserted into a molding die, and after being molded into a desired shape by, for example, vacuum molding, the pre-expanded particles may be filled into the molding die for molding. .

In order to improve the adhesiveness between the skin material 8 and the pre-expanded particles, an adhesive may be provided in advance on the surface of the skin material 8 that contacts the pre-expanded particles. Examples of such an adhesive include a resin dissolved in an organic solvent, a resin emulsion, and a resin powder. Examples of the resin include ethylene-vinyl acetate resin, polypropylene, polyethylene, ethylene-propylene copolymer, chlorinated polypropylene, chlorinated polyethylene, ethylene-propylene-butene terpolymer, and polyolefin resins such as a mixture thereof. However, the present invention is not limited to such examples. The amount of the adhesive used is not particularly limited and may be appropriately adjusted according to the type of adhesive, the desired adhesive strength, and the like.

In the present invention, when the obtained in-mold foam molded article requires a fitting for connecting to another member, for example, the insert material 10 is previously formed on the molding surface of the mold B2. May be provided so that the insert material 10 and the in-mold foam body are integrated with each other during the in-mold foam molding of the pre-expanded particles.

The shape of the insert material 10 may be adjusted according to the shape of the fixture or the like. Examples of the material of the insert material 10 include metal, polyethylene,
Examples include thermoplastic resins such as polypropylene and ABS resin, and thermosetting resins such as phenol resin and formaldehyde resin, but the present invention is not limited to these examples. The surface of the insert material 10 may be preliminarily adhered with, for example, the adhesive or the like in order to improve the adhesiveness with the pre-expanded particles.

After the mold A1 and the mold B2 are clamped, the polypropylene resin pre-expanded particles are filled into the molding chamber 7 of the molding mold through the feeder 9.

Examples of the polypropylene resin used for the pre-expanded polypropylene resin particles include propylene homopolymer, ethylene-propylene random copolymer, ethylene-propylene block copolymer, ethylene-propylene-butene random terpolymer, and propylene-vinyl chloride copolymer. , Propylene-
Resins having a propylene content of 50% by weight or more, such as butene copolymers and propylene-maleic anhydride copolymers, may be used alone or in admixture of two or more.

The polypropylene resin is preferably in a non-crosslinked state, but may be crosslinked with peroxide or radiation.

Further, as the polypropylene resin,
You may use what mixed the other thermoplastic resin which can be mixed with this polypropylene resin. Specific examples of such other thermoplastic resins include, for example, low density polyethylene,
Examples include linear low-density polyethylene, polystyrene, polybutene, and ionomers. The amount of the thermoplastic resin compounded is usually 20 parts or less per 100 parts of the polypropylene resin (parts by weight, the same applies below), especially 5
It is preferably from 10 to 10 parts.

The polypropylene-based resin is usually melted in advance by using, for example, an extruder, a kneader, a Banbury mixer, a roll, etc. so that it can be easily pre-foamed, and it is formed into a columnar shape, an elliptic cylinder shape, a spherical shape, a cubic shape, a rectangular parallelepiped shape, or the like. The desired particle shape, with an average particle size of 0.1-10 m
It is desirable to carry out molding so that the thickness is m, preferably 0.7 to 5 mm.

As a method for producing the polypropylene resin pre-expanded particles, for example, the polypropylene resin particles are made to contain a volatile foaming agent in a pressure vessel, dispersed in water with stirring, and a predetermined foaming temperature is applied under pressure. Examples of the method include a method in which the water dispersion is discharged to a low pressure region after being heated to the low temperature, but the present invention is not limited to such a method.

If the expansion ratio of the polypropylene resin pre-expanded particles is too large, the obtained in-mold foam molded article tends to have a large shrinkage or becomes too soft, and too small. In this case, since the buffering property tends to decrease, it is usually 3 to 60.
Times, preferably 5 to 50 times, more preferably 8 to 45 times,
Particularly preferably, it is 10 to 35 times.

When the polypropylene resin pre-expanded particles are filled into the molding chamber 7 through the feeder 9, the pre-expanded particles are preliminarily pressurized with a pressurized gas, and the pressurized gas is sufficiently contained in the pre-expanded particles. Is penetrated into
It may be filled in the molding chamber 7 in a state where internal pressure is applied,
The pre-expanded particles may be filled in the molding chamber 7 in a compressed state using a pressurized gas, or the pre-expanded particles may be left in the molding chamber 7 without being subjected to internal pressure or compression. However, the present invention is not limited to such a filling method.

After the polypropylene resin pre-expanded particles have been filled in the molding chamber 7, steam is supplied from the vapor holes 4 of the mold B2, and the temperature is lower than the temperature at which the pre-expanded particles fuse with each other. Preheat the pre-expanded particles.

The present invention is also characterized in that the pre-expanded particles are pre-heated at a temperature lower than the temperature at which the pre-expanded particles are fused together. The pre-expanded particles are pre-heated in this manner. In this case, the pre-expanded particles are in a sufficiently heated state without being fused before the main heating is performed, and the uniform heating can be performed evenly by the main heating. In the present invention, during preheating, when the pre-expanded particles are heated to a temperature equal to or higher than the fusion temperature, the pre-expanded particles are preferentially fused from the water vapor hole side, and as a result, Since water vapor does not easily permeate to the pre-expanded particles on the surface material side and defective fusion occurs, preheating is performed at a temperature lower than the fusion temperature of the pre-expanded particles. Since the fusion temperature of the pre-expanded particles cannot be unconditionally determined because it varies depending on the type of resin used in the pre-expanded particles, after examining the fusion temperature of the pre-expanded particles in advance, Mold B
It is preferable to set the temperature of the water vapor introduced from the second vapor hole 4.

The fusion temperature is defined as when the pre-expanded particles are filled in a mold having a depth of about 50 mm and steam at a predetermined temperature (predetermined pressure) is introduced into the mold for 10 to 20 seconds. To
It is the lowest temperature at which the pre-foamed particles are fused to each other and the shape of the in-mold foam molded article can be maintained.

If the temperature of the steam during the preheating is too low, the effect of the preheating tends not to be sufficiently exhibited. Therefore, the temperature of the steam is not higher than the fusion temperature of the pre-expanded particles. The temperature is 35 ° C lower than the fusing temperature, preferably 3 ° C lower than the fusing temperature to 30 ° C lower than the fusing temperature, more preferably 5 ° C lower than the fusing temperature to fusing It is desirable that the temperature is 25 ° C lower than the deposition temperature or higher.

The pressure of the steam during the preheating may be appropriately adjusted so that the temperature of the steam is within the above range.

Another feature of the present invention is that steam is supplied from the steam holes 4 of the mold B2 for preheating and then the pre-expanded particles are steamed with steam. When the pre-expanded particles are steamed with steam, the pre-heated particles may be steamed, or the steam supply may be stopped and the drain valve may be opened. When the pre-expanded particles are steamed in this way, the latent heat of the steam introduced between the pre-expanded particles in the molding chamber 7 can be effectively utilized, and an in-mold foam having a particularly large thickness is produced. In this case, there is an advantage that the pre-expanded particles can be heated uniformly. When steaming the pre-expanded particles in this manner, the time required for such steaming depends on the thickness of the pre-expanded particle layer in the molding chamber 7, the size of the pre-expanded particles,
The rate of heat transfer by water vapor varies depending on the shape and the expansion ratio, so it cannot be determined unconditionally, but normally, when the thickness of the pre-expanded particle layer is, for example, about 50 mm, about 3 seconds or more, preferably about 5 seconds or more. , And more preferably 10 seconds or more.

After the steaming, there is a drain (water content) between the pre-expanded particles, and if main heating is performed in that state, defective fusion of the pre-expanded particles may occur. It is preferable to remove the generated drain. As a method of removing such a drain, for example, the steam chamber 4 provided in the mold B2 is used to form the molding chamber 7
The inside of the mold A is evacuated, and dry air at a temperature high enough to prevent the pre-expanded particles from being fused is aerated through the vapor holes 4 and the mold A
1 and the mold B2, a method of providing a space and removing the drain from the space may be mentioned, but the present invention is not limited to such a method.

Next, the pre-expanded particles are main-heated at a temperature equal to or higher than the temperature at which the pre-expanded particles are fused with each other.

The main heating can be performed by passing steam through the steam holes 4 of the mold B2.

The pressure of the steam may be adjusted so that the temperature of the steam falls within the temperature range described later.

The temperature of the steam may be equal to or higher than the temperature at which the pre-expanded particles are fused with each other. However, if the temperature of the steam is too high, shrinkage of the obtained in-mold foamed molded product may occur. Since it tends to become too large, it is desirable that the temperature is 30 ° C. or higher than the temperature at which the pre-expanded particles are fused, and preferably 25 ° C. or higher than the temperature at which the pre-expanded particles are fused.

After the pre-expanded particles are heated, it is preferable to keep the pre-expanded particles in that state in order to sufficiently transfer the heat from the steam to the pre-expanded particles. The time required for such holding varies depending on the thickness of the pre-expanded particle layer, etc., and therefore cannot be unconditionally determined, but for example, for a pre-expanded particle layer having a thickness of about 50 mm, it takes about 2 seconds. Above, preferably about 5 seconds or more is desirable, but if the time is too long, shrinkage will occur in the obtained in-mold foam molded article, so within the range where shrinkage does not occur during molding. It is preferable to set it appropriately.

Then, the molding die is opened to obtain an in-mold foam molding.

In the present invention, the obtained in-mold foam molded article may be cooled in advance before the mold is opened.

Further, the obtained in-mold foam molded article is separated from the molding die and then, for example, at 3 to 24 under normal pressure of 50 to 80 ° C.
It is preferable to cure and dry for about an hour.

According to the method for producing a polypropylene-based resin in-mold foamed product having a skin according to the present invention, at the same time as producing an in-mold foam from pre-expanded particles even when the skin material does not have air permeability. The skin material and the in-mold foam can be integrated with each other, and an in-mold foam molded article can be produced in which the in-mold foam does not cause defective fusion of pre-expanded particles.

The manufacturing method of the present invention is also used in the molding die.
Using a non-breathable skin material that cannot be heated on both sides by steam holes in the die on the surface, even if the in-mold foam having a large wall thickness and the skin material are integrally molded,
Since it is possible to provide a good in-mold foam molded article without causing the fusion failure of the pre-expanded particles on the surface of the in-mold foam that contacts the skin material, especially the in-mold foam has a relatively large wall thickness, for example, It is also possible to preferably manufacture an in-mold foam molded article having a skin composed of an in-mold foam having an extremely large wall thickness of about 200 mm and a skin material having no air permeability.

Next, the method for producing a polypropylene resin in-mold foamed article having a skin of the present invention will be described in more detail based on examples, but the present invention is not limited to these examples.

Example 1 As a skin material, a vinyl chloride resin sheet (thickness: 1.5 mm) having a woven cloth attached to one surface was made of ethylene-vinyl acetate resin so that the basis weight was 50 g / m ^2. What was sprinkled and adhered to was attached to the inner surface of a flat plate-shaped mold A having no steam holes on the surface to which the woven cloth was attached.

Further, a mold B having a steam hole (vertical 300 mm
, Horizontal 300 mm, depth 50 mm), an iron hook (surface coating: ethylene-vinyl acetate resin) for fixing a set screw was fixed as an insert material to a part of the inner surface.

As pre-expanded polypropylene resin particles, Eperan PP (manufactured by Kanegafuchi Chemical Industry Co., Ltd., trade name, foaming ratio 45 times) was previously placed in a pressure resistant container, and an internal pressure of 2 kg / cm ² · G was given by air pressure. Use a mold and mold it B
The mold A and the mold B were clamped through a feeder provided in the mold to fill the molding chamber of the mold.

Next, steam (vapor pressure) is passed through the steam holes of the mold B.
0.5 kg / cm ² · G, temperature 109-113 ℃) is introduced into the molding chamber and preheated to steam the pre-expanded particles for 10 seconds, and then the internal pressure in the mold is kept below 500 mmHg. The drain and water vapor were sucked and removed using a vacuum pump.

After that, steam (steam pressure 2.4 to 2.8 kg / cm ² · G, temperature 137 to 142 ° C.) was introduced into the molding chamber from the steam holes of the mold B, kept for 25 seconds, cooled with water, and then cooled. The mold A and the mold B were opened to obtain a polypropylene resin in-mold foam molded product having a skin.

As the physical properties of the obtained in-mold foamed molded product, the fusion rate and the adhesiveness to the skin were examined according to the following methods. The results are shown in Table 1.

(A) Fusing rate After making a thin cut on the surface of the obtained in-mold foamed molded product with a knife, it was bent and broken, and the broken surface was observed, and the ratio of the broken area of the foamed particles was expressed as a percentage. And evaluated based on the following evaluation criteria.

(Evaluation Criteria) A: Fusing rate is 60% or more B: Fusing rate is 40 to 59% C: Fusing rate is 20 to 39% D: Fusing rate is 19% or less (b) Skin The adhesiveness of the obtained in-mold foam molded article peels off the skin and the foam,
The state of the interface was observed and evaluated based on the following evaluation criteria.

(Evaluation Criteria) A: Only material breakage is observed in the foam layer.

B: Both material breakage of the foam layer and interfacial peeling between the foam layer and the skin are observed.

C: Interfacial peeling between the skin and the foam layer is observed.

D: The skin and the foam layer are not adhered.

Example 2 Instead of the skin material used in Example 1, a laminated sheet of a vinyl chloride resin sheet (thickness: 0.5 mm) and a polypropylene resin extruded foam sheet (thickness: 2.5 mm) was used. The vinyl chloride resin sheet surface of the laminated sheet is attached to the inner surface side of a flat plate-shaped mold A having no steam holes, and the mold B does not have an insert material and does not have an insert material mounting hole. An in-mold foam molded article was obtained in the same manner as in Example 1 except that the above was used.

The physical properties of the obtained in-mold foam molded article are shown in Example 1.
I examined it in the same way. The results are shown in Table 1.

Example 3 As a skin material, a polyolefin resin sheet (thickness 0.75) was used.
mm) and polypropylene resin extruded foam sheet (thickness 3.
5 mm) and a resin sheet surface of the laminated sheet was attached to the inner surface side of a flat plate-shaped mold A having no steam holes.

Further, a mold B having a steam hole (vertical 300 mm
, 300 mm in width, 50 mm in depth), a hook made of polyolefin resin (surface coating: chlorinated polypropylene) for fixing a set screw was fixed as an insert material to a part of the inner surface.

As pre-expanded polypropylene resin particles, Eperan PP (manufactured by Kanegafuchi Chemical Industry Co., Ltd., trade name, foaming ratio 30 times) was transferred to mold A and mold B through a feeder provided in mold B. Was filled into the molding chamber of the molding die configured by clamping.

Next, steam (vapor pressure) is passed through the steam holes of the mold B.
0.6 kg / cm ² · G, temperature 112-115 ℃) is introduced into the molding chamber of the mold to preheat it, depressurize and steam the prefoamed particles for 10 seconds, then the internal pressure in the molding chamber is 500 m.
The drain and water vapor were sucked and removed by using a vacuum pump so that the pressure became less than mHg.

After that, steam (vapor pressure: 3.2 kg / cm ² · G, temperature: 144 to 146 ° C.) was introduced into the molding chamber from the steam holes of the mold B, kept for 20 seconds, cooled, and then the mold. A
The mold B was opened to obtain a polypropylene resin in-mold foam molded product having a skin.

The physical properties of the obtained in-mold foam molded article are shown in Example 1.
I examined it in the same way. The results are shown in Table 1.

Example 4 As a skin material, a polyolefin resin sheet (thickness 0.75) was used.
mm) and polypropylene resin extruded foam sheet (thickness 3.
5 mm) and a resin sheet surface of the laminated sheet was attached to the inner surface side of a flat plate-shaped mold A having no steam holes.

Also, as the mold B having steam holes, it is 30
The ones with 0 mm, width 300 mm, and depth 150 mm were used.

As pre-expanded polypropylene resin particles, Eperan PP (manufactured by Kanegafuchi Chemical Industry Co., Ltd., trade name, expansion ratio 15 times) was passed through a feeder provided in mold B to mold A and mold B. Was filled into the molding chamber of the molding die configured by clamping.

Next, steam (vapor pressure) is passed through the steam holes of the mold B.
1.0kg / cm ² · G, temperature 117-123 ℃) is introduced into the molding chamber to preheat, depressurize and steam the pre-expanded particles for 15 seconds, then the internal pressure in the molding chamber becomes 260mmHg or less. Thus, the drain and water vapor were sucked and removed using the vacuum pump.

After that, steam (vapor pressure: 3.5 to 3.8 kg / cm ² · G, temperature: 147 to 150 ° C.) was introduced into the molding chamber through the steam holes of the mold B, kept for 30 seconds, cooled, and then cooled. The mold A and the mold B were opened to obtain a polypropylene resin in-mold foam molded product having a skin.

The physical properties of the obtained in-mold foamed molded product are shown in Example 1.
I examined it in the same way. The results are shown in Table 1.

Example 5 As a skin material, a polyolefin resin sheet (thickness 0.75) was used.
mm) and polypropylene resin extruded foam sheet (thickness 3.
5 mm) and a resin sheet surface of the laminated sheet was attached to the inner surface side of a flat plate-shaped mold A having no steam holes.

As a mold B having steam holes,
We used one with 300 mm, width 300 mm, and depth 200 mm.

Eperan PP (manufactured by Kanegafuchi Chemical Industry Co., Ltd., trade name, foaming ratio 15 times) as pre-expanded polypropylene resin particles was transferred to mold A and mold B via a feeder provided in mold B. Was filled into the molding chamber configured by clamping.

Next, steam (vapor pressure) is passed through the steam holes of the mold B.
0.6 kg / cm ² · G, temperature 112-115 ℃) is introduced into the molding chamber to preheat, depressurize and steam the prefoamed particles for 20 seconds, and then the internal pressure in the molding die is 260 mmHg or less. The drain and water vapor were sucked and removed using a vacuum pump so that

After that, steam (vapor pressure: 3.5 to 3.8 kg / cm ² · G, temperature: 147 to 150 ° C.) was introduced into the molding chamber from the steam holes of the mold B, and the mixture was kept for 25 seconds and then cooled. The mold A and the mold B were opened to obtain a polypropylene resin in-mold foam molded product having a skin.

The physical properties of the obtained in-mold foam molded article are shown in Example 1.
I examined it in the same way. The results are shown in Table 1.

Comparative Example 1 A polypropylene resin in-mold foam molded article was obtained in the same manner as in Example 1, except that after preheating, the drain and water vapor were removed by suction without steaming.

The physical properties of the obtained in-mold foamed molded product are shown in Example 1.
I examined it in the same way. The results are shown in Table 1.

Comparative Example 2 In Example 3, a mold B having no insert material and no insert material mounting hole was used.
Further, a polypropylene resin in-mold foam molded article was obtained in the same manner as in Example 3 except that steaming was not performed after preheating.

The physical properties of the obtained in-mold foamed molded product are shown in Example 1.
I examined it in the same way. The results are shown in Table 1.

Comparative Example 3 In Comparative Example 2, except that preheating was not performed,
A polypropylene resin in-mold foam molded article was obtained in the same manner as in Comparative Example 2.

The physical properties of the obtained in-mold foamed molded product are shown in Example 1.
I examined it in the same way. The results are shown in Table 1.

[0084]

[Table 1]

As is clear from the results shown in Table 1, according to the method for producing a polypropylene-based in-mold foamed molded article having a skin of Examples 1 to 5 of the present invention, the skin does not have air permeability. Even if the in-mold foam is manufactured from the pre-expanded particles, the skin material and the in-mold foam can be integrated with good adhesiveness. It can be seen that the particles have an excellent fusion property.

[0086]

EFFECTS OF THE INVENTION According to the method for producing a polypropylene resin in-mold foamed product having a skin according to the present invention, an in-mold foam is produced from pre-expanded particles even if the skin material does not have air permeability. At the same time, the skin material and the in-mold foam can be firmly integrated, and the in-mold foam molded product thus obtained has a large foam layer thickness of, for example, about 200 mm. However, the excellent effect that no defective fusion is generated can be obtained.

[Brief description of drawings]

FIG. 1 is a schematic explanatory view showing one embodiment of a molding die used in the production method of the present invention.

[Explanation of symbols]

 1 Mold A 2 Mold B 4 Steam hole 8 Skin material

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[Procedure amendment]

[Submission date] April 28, 1993

[Procedure Amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0046

[Correction method] Change

[Correction content]

Example 1 As a skin material, a vinyl chloride resin sheet (thickness: 1.5 mm) having a woven cloth attached to one surface thereof was coated with ethylene-vinyl acetate resin on the vinyl chloride resin sheet surface with a basis weight of 50 g / m ² . The thus-sprayed and adhered product was attached so that the surface on which the woven fabric was attached was in contact with the flat plate-shaped mold A having no steam holes.

Claims (7)

[Claims] 1. A molding material is provided by providing a vapor-permeable skin material on the inner surface of a mold A, and the mold A and the mold B are clamped together to form a polypropylene resin pre-expanded particle. It is filled in a mold and steam is supplied only from the steam holes of the mold B without heating the mold A, and the pre-expanded particles are preheated at a temperature lower than the temperature at which the pre-expanded particles are fused with each other. Then
A polypropylene-based resin in-mold foam molded article having a skin characterized in that the pre-expanded particles are steamed with steam, and then the pre-expanded particles are main-heated at a temperature equal to or higher than the temperature at which the pre-expanded particles fuse together. Manufacturing method. 2. The method for producing a polypropylene-based resin in-mold foam molded article according to claim 1, wherein the pre-expanded particles are steamed, the drain is removed, and then main heating is performed. 3. The method for producing a polypropylene-based resin in-mold foam molded article according to claim 1, wherein a preformed skin material is used. 4. The method for producing a polypropylene resin in-mold foam molded article according to claim 1, wherein the polypropylene resin pre-expanded particles are filled in the mold after molding the skin material in the molding die. 5. The method for producing a polypropylene resin in-mold foam molded article according to claim 1, 2, 3 or 4, wherein the skin material is a resin sheet or a laminated sheet of a resin sheet and a polyolefin resin extruded foam sheet. 6. The method for producing a polypropylene resin in-mold foam molded article according to claim 5, wherein the resin sheet is a polyolefin resin sheet. 7. The mold B is provided with an insert material, and then the mold B and the mold A are clamped together.
5. The method for producing a polypropylene resin in-mold foam molded article according to 5 or 6.