JPH09286066A - Production of laminated foam - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent that polypropylene resin foam is crushed and unevenness is generated on the surface of a skin material by using a laminate wherein the skin material, sheet like polypropylene resin foam and a crosslinked polypropylene resin layer with specific thickness are laminated in this order. SOLUTION: A crosslinked sheet of an ethylene/propylene random copolymer is extruded to be bonded to one surface of sheet like polypropylene resin foam 2 under heating and pressure by extusion lamination and a crosslinked polypropylene resin layer with a thickness of 10-900μm is laminated on the crosslinked sheet. Next, a skin material 1 is laminated to the other surface of the polypropylene resin foam 2 by thermal lamination using a two-pack type liquid urethane resin adhesive to obtain a laminate. The crosslinked polypropylene resin layer 3 is interposed between the polypropylene resin foam 2 and a molten polyolefinic resin 5 to prevent the direct contact of the molten polyolefinic resin 5 with the polypropylene resin foam 2 to prevent the crushing of the foam 2.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a method for producing a laminated foam.

[0002]

2. Description of the Related Art Conventionally, as a laminated foam of this type, for example, there is one described in Japanese Patent Application Laid-Open No. 2-102034. This laminated foam is obtained by laminating a cloth such as a soft vinyl chloride sheet on the surface of a polypropylene resin foam, setting it in a molding die, and melting it under appropriate heat and pressure conditions. The resin is laminated on the side of the foamed body and bonded together to be integrated.

[0003]

In the prior art, when the molten polyolefin resin is laminated on the foam side, the foam is softened and crushed by the temperature and pressure of the molten resin, and the thickness of the resin becomes thin and uneven, resulting in partial In addition, there is a problem that the thickness of the foam changes, which affects the skin material that has been attached to the surface of the foam, resulting in unevenness on the surface and impairing the appearance.

The object of the present invention is to pay attention to the above problems and to crush the polypropylene resin foam when the polypropylene resin foam to which the skin material is attached and the molten polyolefin resin are integrally molded. Another object of the present invention is to provide a method for producing a laminated foam that does not cause unevenness on the surface of the skin material.

[Means for Solving the Problems]

The present invention has been made in order to achieve the above-mentioned object. A skin material, a sheet-shaped polypropylene resin foam and a crosslinked polypropylene resin layer having a thickness of 10 to 900 μm are laminated in this order. The molten polyolefin resin is laminated and integrated on the crosslinked polypropylene resin surface of the laminated body.

The skin material used in the present invention is a cloth-like material using natural or artificial fibers, a polyvinyl chloride resin sheet,
It is a known sheet such as a thermoplastic elastomer sheet, a laser, or a mixed sheet of a polyvinyl chloride resin and an ABS resin in which acrylonitrile, butadiene, and styrene are copolymerized, among which a polyvinyl chloride resin sheet. -G is preferred.

As the polypropylene resin foam used in the present invention, any conventionally known polypropylene resin foam sheet can be used. The production method is also optional, but in general, a polypropylene-based resin, a heat-decomposable foaming agent, a chemical crosslinking agent, a crosslinking accelerator, an antiaging agent, a pigment, a foamable polypropylene-based resin composition containing other additives It is produced by kneading and molding at a temperature below the decomposition temperature and then foaming by heating. The crosslinking may be carried out by irradiation with ionizing radiation.

Examples of the polypropylene resin include homopolymers of propylene, block copolymers and random copolymers with olefinic monomers such as ethylene having 50% by weight or more of a propylene component, ethylene and butene. A terpolymer such as an olefinic monomer is used.

As the thermal decomposition type foaming agent, any agent having a thermal decomposition temperature higher than the melting temperature of the resin composition can be used. For example, azodicarbonamide, hydrazide carbonamide having a thermal decomposition temperature equal to or higher than that of azodicarbonamide, barium azodicarboxylic acid salt, dinitrosopentaethylenetetramine, nitrosoguanidine, P, P′-oxybisbenzenesulfonyl semicarbazide Etc.
These may be used alone or in combination of two or more. The content of the thermal decomposition type foaming agent is preferably 0.01 to 30% by weight, and more preferably 0.05 to 15% by weight of the propylene resin.

As the crosslinking accelerator, divinylbenzene,
Diallylbenzene, divinylnaphthalene, polyethylene dimethacrylate, trimethylol propane methacrylate, triallyl isocyanurate and the like are used. These may be used alone or in combination of two or more. The content of the crosslinking accelerator is preferably 0.01 to 30% by weight, and more preferably 0.01 to 15% by weight of the propylene resin.

As the peroxide used together with the crosslinking accelerator for chemical crosslinking, methyl ethyl ketone peroxide,
T-butylperoxide, dicumylperoxide and the like are used. The content of the peroxide is preferably 0.01 to 10% by weight of the propylene resin, and 0.05 to 5% by weight.
Is preferred.

The density of the polypropylene resin foam is 0.
02 to 0.2 g / cc is preferable, and 0.05 to 0.11 g / cc is taken into consideration in consideration of cost reduction and heat and pressure resistance during molding.
Is preferred.

The polypropylene resin forming the crosslinked polypropylene resin layer used in the present invention includes a propylene homopolymer and a block copolymer with an olefin monomer such as ethylene having a propylene component of 50% by weight or more. Examples include polymers, random copolymers, and terpolymers of olefinic monomers such as ethylene and butene.
Inorganic compounds such as talc, oxalic acid, and calcium carbonate may be filled as long as the characteristics of the resin are not impaired.

The polypropylene resin layer must be crosslinked, but in the case of chemical crosslinking, the above-mentioned crosslinking accelerator of the expandable polypropylene resin composition and peroxide are used. Further, after forming the layer, it may be crosslinked by irradiation with ionizing radiation. The degree of crosslinking of the crosslinked polypropylene resin layer is preferably 40 to 65%.

The thickness of the crosslinked polypropylene resin layer is 1
If the thickness is less than 0 μm, the heat of the molten polyolefin-based resin is easily transferred to the surface of the polypropylene-based resin foam during molding, the strength of the surface area decreases and softens, and it is crushed when integrated. To do. Further, if it exceeds 900 μm, the moldability is deteriorated. From this, it is limited to 10 to 900 μm.

The method for laminating the crosslinked polypropylene resin layer on the polypropylene resin foam is, for example, preliminarily laminating the polypropylene resin layer on the foaming polypropylene resin sheet, or coextruding it, and then ionizing radiation. Examples thereof include a method of crosslinking and foaming, a method of thermally laminating a crosslinked polypropylene resin layer on a polypropylene resin foam, and the like.

Examples of the polyolefin resin used in the present invention include a propylene resin, a random copolymer mainly containing propylene and an α-olefin, a random block copolymer, and a block copolymer. You may mix polyethylene resin with this. Furthermore, talc,
Inorganic compounds such as oxalic acid and calcium carbonate may be filled as long as the characteristics of the resin are not impaired.

In the present invention, there are various methods for obtaining a laminated foam of the present invention by laminating a polyolefin resin on the laminate, but a stamping molding method is preferable. In the stamping molding method, molten polyolefin resin is poured into the lower mold of the mold, and a laminate obtained by laminating a skin material, a polypropylene resin foam, and a crosslinked polypropylene resin layer is used as an upper mold and a lower mold. It is a method of sandwiching with and pressurizing to integrally mold.

(Function) Since the skin material, the polypropylene-based resin foam and the cross-linked polypropylene-based resin layer having a thickness of 10 to 900 μm are laminated in this order, between the polypropylene-based resin foam and the polyolefin-based resin as the base material. The crosslinked polypropylene resin layer is interposed between the polypropylene resin foam and the polypropylene resin foam does not come into contact with the melted polyolefin resin and is not crushed. Further, since the crosslinked polypropylene resin layer and the polyolefin resin are both olefin resins, they are fused and integrally molded.

[0020]

Embodiments of the present invention will be described in detail below with reference to the drawings. FIG. 1 (a) is an explanatory view of a state where molten polyolefin resin is injected into the laminate and the mold, (b)
2 is an explanatory view of a state in which pressure is applied in the mold for integral molding, FIG.
FIG. 3 is a perspective view of a laminated foam obtained by the manufacturing method of the present invention.

FIG. 2 shows a cross-linked polypropylene resin layer 3 surface of a laminate 4 in which a skin material 1, a polypropylene resin foam 2, and a cross-linked polypropylene resin layer 3 having a thickness of 10 to 900 μm are laminated in this order. It shows a laminated foam body in which the melted polyolefin resin 5 is laminated and integrated.

[0022]

【Example】

(Example 1) This laminated foam is prepared as follows.
First, 70 parts by weight of an ethylene-propylene random copolymer containing 4% ethylene was mixed with 30 parts of a low-density polyethylene resin.
By weight, 5 parts by weight of divinylbenzene, 4, 6, 8, 10 and 12 parts by weight of azodicarbonamide, respectively, were obtained, and 5 kinds of compositions having different contents of azodicarbonamide were prepared by extrusion molding. Sheet was obtained.

After cross-linking the obtained 5 kinds of sheets by irradiation of 4 mega-rats with ionizing radiation, continuous heat foaming was carried out at 250 ° C., and 5 kinds of sheets each having a thickness of 3 mm and different expansion ratios were formed. -Shaped polypropylene resin foam 2
I got

Next, one sheet of the obtained sheet-like polypropylene resin foam 2 is crosslinked with an ethylene-propylene random copolymer containing 4% ethylene (two kinds of melt indexes 20 and 30). Sheet (60% crosslinking)
Was heat-sealed by extrusion lamination to laminate a crosslinked polypropylene resin layer 3 having a thickness of 10 μm.

Next, the skin material 1 (vinyl chloride resin sheet having a thickness of 0.5 mm) is heat-laminated on the other surface of the polypropylene resin foam 2 using a two-component urethane resin adhesive.
To obtain a laminate.

Next, the polyolefin-based resin 5 (4% of the melt index 30) is provided substantially in the center of the concave portion of the lower mold 62 of the mold 6.
An ethylene-containing ethylene-propylene random copolymer) was injected, the laminate 4 was sandwiched between the upper mold 61 and the lower mold 62, and pressed by the convex portion of the upper mold 61 to obtain a laminated foam.

Example 2 A laminated foam was obtained in the same manner as in Example 1 except that the thickness of the crosslinked polypropylene resin layer 3 was changed to 30 μm. Since the manufacturing method is the same as that of the first embodiment, the description thereof will be omitted.

Example 3 A laminated foam was obtained in the same manner as in Example 1 except that the thickness of the crosslinked polypropylene resin layer 3 was changed to 50 μm. Since the manufacturing method is the same as that of the first embodiment, the description thereof will be omitted.

Example 4 A laminated foam was obtained in the same manner as in Example 1 except that the thickness of the crosslinked polypropylene resin layer 3 was changed to 100 μm. Since the manufacturing method is the same as that of the first embodiment, the description thereof will be omitted.

Example 5 A laminated foam was obtained in the same manner as in Example 1 except that the thickness of the crosslinked polypropylene resin layer 3 was changed to 200 μm. Since the manufacturing method is the same as that of the first embodiment, the description thereof will be omitted.

Example 6 A laminated foam was obtained in the same manner as in Example 1 except that the thickness of the crosslinked polypropylene resin layer 3 was changed to 300 μm. Since the manufacturing method is the same as that of the first embodiment, the description thereof will be omitted.

Comparative Example 1 A laminated foam was obtained in the same manner as in Example 1 except that the thickness of the crosslinked polypropylene resin layer 3 was changed to 950 μm. Since the manufacturing method is the same as that of the first embodiment, the description thereof will be omitted.

Comparative Example 2 A laminated foam was obtained in the same manner as in Example 1 except that the thickness of the crosslinked polypropylene resin layer 3 was changed to 5 μm. Since the manufacturing method is the same as that of the first embodiment, the description thereof will be omitted.

Next, in order to explain the features of the present invention, the skin material 1 after molding of Examples 1 to 6 of the present invention and Comparative Examples 1 and 2 is described.
Tables 1 and 2 show the physical properties regarding the unevenness of the surface. Table 1 shows melt index 30 of polyolefin resin 5.
Table 2 shows a comparison of the polyolefin resin 5 with a melt index of 20.

Next, in order to explain the features of the present invention, Tables 1 and 2 compare the case where the polypropylene resin layer 3 is a crosslinked polypropylene resin and the case where it is an uncrosslinked polypropylene resin. .

[0036]

[Table 1]

[0037]

[Table 2]

As shown in Tables 1 and 2, Examples 1 to 6
Then, the thickness of the cross-linked polypropylene resin layer 3 is 10 μm.
As described above, it was possible to obtain a good sheet without unevenness on the surface of the skin material 1 after molding. (The density measurement of the polypropylene resin foam and the criteria for determining the quality of the unevenness of the skin material after molding will be described later.) In Comparative Example 1, since the thickness of the crosslinked polypropylene resin layer 3 is 950 μm, the skin material after molding The surface of No. 1 was uneven, and in Comparative Example 2, the thickness of the crosslinked polypropylene resin layer 3 was as thin as 5 μm, so that the surface of the skin material 1 was markedly uneven, and in each case a good laminated foam was obtained. No
It lacked practicality.

The density of the sheet-shaped polypropylene resin foam 2 was measured as follows. A sheet-shaped polypropylene resin foam 2 before extrusion lamination of an ethylene-propylene random copolymer and heat lamination of the skin material 1 is used, and this is 10 × 10
The sheet was cut into cm, the weight and volume of this cut sheet were measured, and the weight was divided by the volume to obtain the density.

Further, the quality of the unevenness of the surface of the skin material 1 after molding was judged as follows. One surface of the skin material of the obtained laminated foam was observed with a magnifying glass and visually, and judged as follows. ⊚: No unevenness observed with a magnifying glass. ◯: There is no unevenness when visually observed. X: Some irregularities are observed visually. XX: Visible unevenness is partially observed by visual observation.

Although the embodiments of the present invention have been described in detail above with reference to the drawings, the specific configuration is not limited to these embodiments,
The present invention includes even design changes and the like within the scope of the present invention.

[0042]

The method for producing a laminated foam of the present invention is as described above, and a skin material, a sheet-like polypropylene resin foam and a crosslinked polypropylene resin layer having a thickness of 10 μm or more are laminated in this order. Since we are using a laminated body,
A crosslinked polypropylene resin layer is interposed between the polypropylene resin foam and the melted polyolefin resin,
The melted polyolefin resin does not directly contact the polypropylene resin foam, and the polypropylene resin foam is not crushed. Further, since the crosslinked polypropylene resin layer and the polyolefin resin are both olefin resins, they are fused and integrally molded.
Molding is easy and convenient.

[0043]

[Brief description of drawings]

FIG. 1A is an explanatory view of a state in which a molten polyolefin resin is injected into a laminated body and a mold, and FIG. is there.

FIG. 2 is a perspective view of a laminated foam obtained by the manufacturing method of the present invention.

[Explanation of symbols]

 1 Skin Material 2 Polypropylene Resin Foam 3 Crosslinked Polypropylene Resin Layer 4 Laminate 5 Polyolefin Resin 6 Form 61 Upper Mold 62 Lower Mold

Claims (1)

[Claims] 1. A molten polyolefin on the surface of a crosslinked polypropylene resin layer of a laminate in which a skin material, a sheet-shaped polypropylene resin foam and a crosslinked polypropylene resin layer having a thickness of 10 to 900 μm are laminated in this order. 1. A method for producing a laminated foam, which comprises laminating and integrating a series of resins.