JP3167905B2 - Heat resistant heat adhesive film - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat-bonding film having good heat resistance, and more particularly to a heat-bonding film useful for manufacturing ceiling materials for automobile interiors and the like.

[0002] The present invention provides a heat adhesive film having good heat resistance,
Particularly, the present invention relates to a heat-adhesive film useful for manufacturing ceiling materials for automobile interiors and the like. However, the term “thermal adhesive film” as used herein means a film-like adhesive used for adhering sheets, molded products thereof, and the like (the same applies hereinafter in this specification).

[0003] For example, ceiling materials for automobile interiors are made of nonwoven fabric /
It is a three-layer structure of foamed polyurethane + glass fiber / non-woven fabric, but a heat-bonding film is used to bond each layer. After layer-forming materials are laminated with the heat-bonding film interposed, the layers are heated under a mold. It is manufactured by a method in which molding and bonding are performed at once by pressing.

[0004] The main performances required of the thermal adhesive film for such applications are as follows. Can be used for bonding various materials such as non-woven fabric, polyurethane foam, and glass fiber. When hot-pressing with a mold, there is no hole in the film even if there is a part that is greatly extended locally. As a result, air around the pinhole becomes black as a result of dirt in the air adhering as a result of air in and out of the vehicle passing therethrough.)

In recent years, there has been a tendency to set the mold temperature high in order to improve the productivity by shortening the cycle of thermal bonding / molding, and the mold temperature may reach 150 ° C. There is little deterioration in physical properties even when used in a room, and no holes are opened. In recent years, the use conditions of automobiles have become increasingly severe, and the test temperature of a heat resistance test has tended to be higher even in a product test. Laminates made of conventional thermal adhesive films cannot withstand this high-temperature test, and the ceiling material may lose its shape.

[0006] However, it is difficult for the above-mentioned conventional thermal adhesive film using a high-density polyethylene as a base layer to meet these demands for sophistication.

A general-purpose film having better heat resistance than a high-density polyethylene film is a polypropylene film. This polypropylene has a melting point of about 30 to 40 ° C higher than polyethylene, maintains excellent physical properties even at high temperatures exceeding 100 ° C, and is inexpensive. Can be improved. However, the polypropylene film has a poor affinity for a general thermoadhesive resin such as an ethylene copolymer, and the lamination by the coextrusion method results in insufficient interlayer strength. In addition, even though the interlayer strength at room temperature can be achieved by using a special heat-adhesive resin, the interlayer peel strength is significantly reduced under severe temperature conditions. Therefore, a heat-resistant heat-adhesive film exhibiting the level of adhesive strength (about 1 kgf / 15 mm or more) required for bonding industrial materials cannot be obtained only by changing the base material layer to a polypropylene film.

[0008]

SUMMARY OF THE INVENTION Accordingly, the present invention is to provide a high-performance heat-adhesive film which has better adhesive strength and heat resistance than conventional heat-adhesive films and can withstand use under the above-mentioned severe conditions. It is assumed that.

[0009]

Means for Solving the Problems A thermal adhesive film of the present invention which has successfully attained the above object has a polypropylene film as a base layer, and a thermal adhesive layer made of an ethylene copolymer on the surface. It is characterized in that an intermediate layer made of a metallocene polymer having a density of preferably 0.915 g / cm ³ or less is provided between the layer and the substrate layer.

The term "metallocene polymer" as used herein means a linear low-density polyethylene produced by a gas phase method using a so-called metallocene catalyst. The metallocene catalyst and the method for producing linear low-density polyethylene using the same are described in US Pat.
A (Pakpia), vol. 501, pp. 10-52 (April 1994), Plastic Age 40, pp. 145-164 (January 1994), etc. It is commercially available from several companies.

As described above, since a polypropylene film has a poor affinity for a general thermo-adhesive resin such as an ethylene copolymer, a laminate of these materials has an insufficient interlayer strength. By providing such an intermediate layer, the laminated structure can be strengthened without impairing other performances required for the heat-adhesive film, and the risk of adhesive destruction due to delamination can be eliminated.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a method for producing a heat-adhesive film according to the present invention will be described. As the polypropylene film used as the base layer, a film made of a polypropylene homopolymer is most suitable if heat resistance is emphasized, but is not limited thereto, and a film made of various copolymerized polypropylenes can also be used. .

As the thermal adhesive layer on the surface, a material having an appropriate softening point and adhesive performance as a material constituting the thermal adhesive layer is appropriately selected from ethylene copolymers and used. It is not necessary to consider the affinity with the substrate layer made of polypropylene. Preferred specific examples of usable ethylene copolymers include the following.

Ethylene / acrylic acid copolymer (acrylic acid copolymerization ratio of about 5 to 9% by weight. If it is less than 5% by weight, the thermal adhesive strength is insufficient. Mitsubishi Polyethylene EAA, etc.)

An ethylene / methyl methacrylate copolymer (the copolymerization ratio of methyl methacrylate is about 10 to 2)
5% by weight. If the amount is less than 10% by weight, the thermal adhesion is insufficient. For example, Aclift of Sumitomo Chemical Co., Ltd. )

A blend of an ethylene / ethyl acrylate / maleic anhydride terpolymer (for example, Bondyne of Sumika Atochem) and the above-mentioned ethylene / methyl methacrylate copolymer (the blend ratio of the former is about 5 to 5)
90% by weight)

The metallocene polymer used as the intermediate layer has a density of 0.915 or less (so-called V-LDP).
E) is desirable, and those having a higher density than this do not have a sufficient use effect because they have poor affinity for the base material layer. Examples of preferred commercial products include Kernel of Mitsubishi Chemical Corporation, Evolu of Mitsui Petrochemical Corporation, and Exelen of Sumitomo Chemical Co., Ltd.

The lamination of the base layer composed of a polypropylene film, the intermediate layer and the surface heat bonding layer is preferably carried out simultaneously with the film formation by a co-extrusion method, but the lamination method is not limited to this. When laminating the surface resin layer using a polypropylene film formed in advance, the polypropylene film is preferably a non-stretched film.

The thickness of each layer in the heat-adhesive film of the present invention is not particularly limited, but it is necessary that the heat-adhesive resin layer on the surface be about 10 to 15 μm from the viewpoint of adhesive strength. The thickness of the layer is required to be about 10 to 15 μm in order to improve the physical properties (particularly, pinhole resistance) of the whole laminate. The thickness of the intermediate layer made of a metallocene polymer is suitably about 3 to 15 μm. Further, it is desirable that the total thickness be about 30 to 90 μm from the viewpoint of workability of thermal bonding.

The thermal adhesive film according to the present invention can be used for manufacturing ceiling materials, sheet materials, wall materials and the like for automobile interiors in the same manner as conventional thermal adhesive films. The mold temperature when performing thermal bonding can be increased up to about 150 ° C.

[0021]

EXAMPLES Examples 1 and 2; Comparative Example 1 A polypropylene homopolymer as a base material layer, an ethylene / acrylic acid copolymer (acrylic acid 7% by weight) as a surface layer, and a metallocene polymer (Mitsui Petrochemical Co., Ltd.) as an intermediate layer. (Embodiment, density: 0.910 g / cm ³ or 0.905 g / cm ³ ), and a heat-adhesive film of the present invention composed of a laminated film having a thickness of 10 μm and a total thickness of 50 μm was produced by a co-extrusion method (Example). 1,2).

For comparison, a laminated film was produced in the same manner except that no intermediate layer comprising a metallocene polymer was provided (Comparative Example 1).

The obtained laminated films were measured for the delamination strength (measuring method: tensile speed: 200 mm / min, 90 ° peeling), and these laminated films were thermally bonded between polyester nonwoven fabrics (conditions: 150 ° C., 3 kgf). / cm ² , 30 seconds), and the adhesive strength was measured (adhesive strength measuring method: tensile speed 300 mm / min, 180 ° peeling). Further, in order to examine the heat resistance, the adhesive strength was measured even after the bonded nonwoven fabric was heated at 100 ° C. for 3 hours. Table 1 shows the results.

[0024]

Table 1 Metallocene polymer Interlaminar peel strength Adhesive strength Adhesive strength (after heating) Density (g / cm ³ ) (g / 15 mm) (kg / 25 mm) (kg / 25 mm) Example 1 0.910>500> 2. 5> 2.5 Example 2 0.905>500>2.5>2.5> 2.5 Comparative Example 1-0 00

Example 3 and Comparative Example 2 A blend of 20 parts by weight of an ethylene / ethyl acrylate / maleic anhydride terpolymer (bondine) and 80 parts by weight of an ethylene / methyl methacrylate copolymer (Aclift) was used as a surface layer. A heat-bonding film was produced in the same manner as in Example 2 except that the heat-bonding film was used. For comparison, a laminated film was produced in the same manner except that the intermediate layer made of a metallocene polymer was not provided (Comparative Example 2). Table 2 shows the results.

[0026]

[Table 2] Delamination strength Adhesive strength Adhesive strength (after heating) (g / 15mm) (kg / 25mm) (kg / 25mm) Example 3>500>2.5> 2.5 Comparative Example 2>500> 2 .5 0.8

Example 4 Using the heat-adhesive films of Examples 2 and 3 and Comparative Example 2, a ceiling material for automobile interior (nonwoven fabric /
(Three-layer structure of foamed polyurethane + glass fiber / nonwoven fabric) was laminated and molded. About the obtained ceiling material, the peel strength of the nonwoven fabric layer was measured. The measurement of the peel strength was 1
The test was also performed on the sample after heating to 00 ° C. for 3 hours.
Table 3 shows the measurement results.

[0028]

[Table 3] Thermal adhesive film peel strength (kg / 25mm) Same as on the left (after heating at 100 ° C) Example 2>2.5> 2.5 Example 3>2.5> 2.5 Comparative example 2> 2.5 0.8

It is to be noted that each ceiling material has a temperature of 100.degree.
No change in shape due to heating for hours was observed.

[0030]

As described above, the heat-adhesive film of the present invention has an intermediate layer made of a low-density metallocene polymer interposed between a base material layer made of polypropylene and a surface heat-adhesive layer made of an ethylene copolymer. In this method, the bonding between the base material layer and the heat bonding layer is strong, and the integrity thereof is maintained well even when heated. In addition, it has excellent thermal adhesive strength and good handling properties when used for thermal bonding.

Therefore, the heat-adhesive film of the present invention can sufficiently exhibit the advantageous properties of the heat-resistant base material layer made of polypropylene, and can withstand adhesive molding under severer conditions than conventional heat-adhesive films. The product can also withstand use at higher temperatures than conventional products.

Claims (3)

(57) [Claims] 1. A polypropylene film as a base layer,
Adhering sheets and molded products thereof, having a heat bonding layer made of an ethylene copolymer on the surface and having an intermediate layer made of a metallocene polymer between the heat bonding layer and the base material layer Heat bonding film for. 2. A polypropylene film as a base material layer,
It has a thermal adhesive layer made of an ethylene copolymer on the surface, and has an intermediate layer made of a metallocene polymer having a density of 0.915 g / cm ³ or less between the thermal adhesive layer and the base material layer. , Heat bonding film for bonding sheets and molded products. 3. An ethylene / acrylic acid copolymer, an ethylene / methyl methacrylate copolymer, and an ethylene / acrylic acid copolymer.
3. The thermal adhesive layer according to claim 1, wherein an ethylene copolymer selected from the group consisting of a blend of an ethyl acrylate / maleic anhydride terpolymer and an ethylene / methyl methacrylate copolymer is used for the thermal adhesive layer. Heat resistant heat adhesive film.