JP2518606B2 - Base material for automobile molding ceiling material - Google Patents

Description

TECHNICAL FIELD The present invention relates to a base material for automobile molding ceiling material.

[Conventional technology]

Conventionally, an automobile ceiling material has a cushion material made of polyurethane foam or the like, which is attached to the indoor side surface of a molded body formed by molding a thermoplastic resin foam-based base material for an automobile molded ceiling material into a ceiling material shape, Further, it is constructed by laminating a cover material such as a synthetic resin sheet or a woven fabric.

These base materials for automobile molding ceiling materials are composed of only various thermoplastic resin foams, or those in which various thermoplastic resin films or sheets are laminated on both sides of these foams (for example, JP-A- 53-32514) and the like are used.

[Problems to be solved by the invention]

However, conventional base materials for automobile molding ceiling materials, which are made only of foam, do not always have sufficient mechanical strength such as compressive strength and maximum bending load, and also have poor thermal strength such as beespan, resulting in temperature change. There is a problem such as deformation due to long-term use in a car interior that is extremely severe, and a film or sheet laminated on both sides of foam can improve mechanical strength, thermal strength, etc. to some extent, but is still satisfactory. It wasn't a pile.

The present invention has been made in view of the above points, and an object of the present invention is to provide a base material for an automobile molding ceiling material, which is excellent in mechanical strength and thermal strength.

[Means for solving problems]

The inventors of the present invention have conducted extensive studies to develop a base material for automobile molding ceiling material having excellent mechanical strength and thermal strength, and as a result, the foam surface based on a thermoplastic resin having a Vicat softening point of 115 ° C. or higher. Further, they have found that a laminated foam provided with a biaxially stretched thermoplastic resin film is excellent as a base material for automobile molding ceiling materials, and completed the present invention.

That is, the base material for automobile molded ceiling material of the present invention comprises a biaxially stretched thermoplastic resin film provided on the surface of a biaxially stretched foam made of a thermoplastic resin having a Vicat softening point of 115 ° C. or higher. The thermoplastic resin of the foam is a styrene-acrylic copolymer, and the stretching degree of the foam is 5 each.
-40%, the thermoplastic resin of the film is a styrene-acrylic copolymer, and the stretching degree of the film is 15-60%.

 Hereinafter, the present invention will be described in detail with reference to the drawings.

FIG. 1 shows an example of an automobile molding ceiling material base material of the present invention in which a tubular foam is flattened and the foam is used.
Is a base material for automobile molded ceiling materials. The base material 1 is a foamed body 2 formed by integrally pressing a tubular foamed body obtained by extruding a thermoplastic resin into a flat shape by pressing it, and fusing the inner surface side together, and both sides of the foamed body 2. And the thermoplastic resin films 3 and 3 provided on the.

As shown in FIG. 2, the base material 1 is a cylindrical foamed product obtained by kneading a thermoplastic resin and a foaming agent in a molten state in an extruder 4 and extruding and foaming them by a circulator mounted at the tip of the extruder 4. 5 to guide rollers 6,6 ... and pinch rollers 7,7
Are formed into a flat shape by pressing, and the inner surface 8 of the foam is fused and integrally formed, and then the thermoplastic resin films 3 and 3 are heat-fused by the heating rollers 9 and 9, or the like.

Although the thermoplastic resin film is provided on both surfaces of the foam in FIG. 1, it is not limited to this and may be provided on only one surface of the foam.

Further, the thermoplastic resin film 3 is provided on the surface of the foam body 2 by heat fusion, but the invention is not limited to this, and it is also possible to laminate by laminating.

The thermoplastic resin forming the foam 2 is styrene-
An acrylic copolymer is used, and specifically, styrene-acrylic acid copolymer resin, styrene-methacrylic acid copolymer resin; methyl acrylate, ethyl acrylate,
Examples thereof include acrylic acid esters such as methyl methacrylate, copolymer resins of methacrylic acid esters and styrene; copolymer resins of acrylamide, acrylate, methacrylic acid salts and styrene. Among the above resins, styrene-acrylic acid copolymer resin and styrene-methacrylic acid copolymer resin are preferable because of their excellent heat resistance and moldability.

Further, as the thermoplastic resin forming the film 3, a styrene-acrylic copolymer is used, and specifically, the styrene-acrylic copolymer mentioned as the resin forming the foam or the styrene is used. -Acrylic copolymer resins obtained by modifying rubbers are listed. The above-mentioned rubber-modified resin is obtained by, for example, graft-polymerizing a monomer constituting the resin to polybutadiene, polyisoprene or the like. Among these resins, a rubber-modified styrene-acrylic acid copolymer resin and a rubber-modified styrene-methacrylic acid copolymer resin are preferable because they have excellent thermal strength and impact strength.

Further, the thermoplastic resin forming the foam 2 and the film 3 may be mixed with the resin within the intended range of the present invention.

The Vicat softening point of the thermoplastic resin used for the foam 2 must be 115 ° C. or higher, and particularly preferably 120 ° C. or higher. When the Vicat softening point is less than 115 ° C, the heat resistance is poor and the intended purpose of the present invention cannot be achieved. Alternatively, the Vicat softening point of the thermoplastic resin used for the film 3 is also preferably 115 ° C. or higher.

Further, the foam 2 preferably has a residual foaming agent amount of 0.01 to 3% by weight, and by setting the residual foaming agent amount within the above range, the foam 2 is excessively affected by the plasticizing action when heated. It is preferable for molding.

The foaming agent used in the production of the foam 2 is arbitrarily selected from the foaming agents used for ordinary foaming, and examples thereof include aliphatic hydrocarbons such as propane, butane, n-pentane and isopentane, and dichlorodiene. Examples thereof include halogenated hydrocarbons such as fluoromethane, tetrafluoroethane, trichlorofluoromethane, methyl chloride and ethyl chloride, and ethers such as methyl ether and ethyl ether.
Of these, a mixture of dichlorodifluoromethane and methyl chloride and / or ethyl chloride is preferable for molding. Further, the expansion ratio of the foamed body 2 can be improved, the amount of the residual foaming agent contained in the foamed body 2 can be set within the above range, and the tubular foamed body 5 can be reliably fused. Therefore, dichlorodifluoromethane is used as the foaming agent. It is preferable to use 1 to 6 parts by weight of a mixed foaming agent, which is a mixture of 5 to 95:80 and 20:20 and methyl chloride and / or ethyl chloride in a weight ratio with respect to 100 parts by weight of resin.

The film 3 is biaxially stretched and the degree of stretching is 15 to 60%. By setting the stretching degree of the film 3 as described above, the thickness of the film 3 can be reduced and the physical properties of the substrate 1 can be improved. The degree of stretching of the film 3 is expressed by the heat shrinkage (dimensional change) when heated in an oil bath at 135 ° C. for 20 seconds, the length before heating is a, and the length after shrinking after heating is b. In this case, it is calculated by the following equation (1).

Heat shrinkage (%) = (ab) / a × 100 (1) Further, the foam 2 is also biaxially stretched in the range of 5 to 40%. The degree of stretching is particularly preferably in the range of 15-40%. Cylindrical foam 5 for controlling the degree of stretching within the above range
Blow-up ratio during extrusion foaming of
When L ₁ and the width of the foam 2 are L ₂ , the tubular shape is such that (L ₂ × 2) / L ₁ value) is larger than 3 (that is, (L ₂ × 2) / L ₁ > 3). It is preferable to foam the foam 5.

The beam span of the base material 1, especially the beam span, is dramatically improved by the synergistic effect that the foam 2 and the film 3 are stretched biaxially and the inner surface 8 is fused as described above. It

The degree of stretching of the foam 2 is represented by the heat shrinkage rate (dimensional change) when heated in an oven at 150 ° C. for 100 seconds. As in the case of the foam, the length before heating is a and shrinkage after heating is performed. It is obtained from the above equation (1), where the subsequent length is b.

The film 3 preferably has a thickness of 20 to 250 μm. If the thickness of the film is less than 20μ, the thermal strength such as beam span and the mechanical strength such as maximum bending load are inferior.
If it exceeds, there is a problem in weight reduction, and the cost becomes high.
Further, the substrate 1 preferably has a total thickness of 2 to 10 mm in order to obtain sufficient mechanical strength.

In the present invention, when the film 3 is provided on only one side of the foam 2, a skin layer may be formed on one side without the film 3. By forming the skin layer, the compressive strength and the maximum bending load of the base material 1 can be further improved. The skin layer can be formed by a method such as cooling the outer surface of the tubular foam 5 foamed by the extruder 4.

Also, the basis weight of the base material 1 (g / m ²⁾ is preferably 250~600g / m ^2. If it is less than 250 g / m ^2, there are cases where the mechanical strength cannot be sufficiently satisfied, and if it exceeds 600 g / m ² , there is a problem in weight reduction and the cost becomes high.

The base material 1 for automobile molded ceiling material configured as described above is molded into a predetermined automobile ceiling material shape as shown in FIG. 3, and then a cushion material 10 made of polyurethane foam or the like is attached to the surface on the indoor side. Further, an automobile ceiling material 12 is formed by bonding a surface material 11 made of a synthetic resin sheet such as vinyl chloride or a woven cloth on the front surface of the cushion material 10 on the indoor side.

The Vicat softening point in the present invention is ASTM D-15.
The value measured by 25.

Further, the base material 1 is described as a case where the foamed body 2 is formed by pressing the tubular foamed body into a flat shape and fusing the inner surface side to be integrally formed, but the present invention is not limited to this. It is also possible to use a foam formed by ordinary extrusion foaming using a T-die, etc. However, since the flat inner surface is fused, the maximum bending load, beam span, etc. The former, whose physical properties are improved, is more preferable.

〔Example〕

 Hereinafter, the present invention will be described in more detail with reference to examples.

Examples 1 to 3 and Comparative Examples 1 to 2 With respect to 100 parts by weight of styrene-methacrylic acid copolymer resin (Vicat softening point 126 ° C.) in the extruder, dichlorodifluoromethane and methyl chloride or chloride shown in Table 1 were used. After melt-kneading a mixed foaming agent consisting of ethyl, a cylindrical foam is extruded and foamed with a blow-up ratio shown in Table 1 from a circular die, and then the cylindrical foam is pressed to form a flat shape, A plate-shaped foam was obtained by fusing the inside surface of the foam with a pressing force.

Then, for Examples 1 to 3, a rubber-modified styrene-methacrylic acid copolymer resin (Vicat softening point 120
C.) as a base resin and biaxially stretched films having the thickness shown in Table 1 are laminated on both sides of the foam, and in Comparative Example 1, the above resin is used as the base resin. An unstretched film having a thickness shown in Table 1 was laminated on both sides of the foam to obtain a laminated foam. These laminated foams and Comparative Example 2
Table 1 shows the properties of the foamed product in which the film is not laminated.

Next, the laminated foams obtained in Examples 1 to 3 and Comparative Example 1 and the foams in which no film was laminated in Comparative Example 2 were molded using a headliner molding die. Table 1 shows the results of measuring the physical properties of the laminated foam and the foam after molding.

Comparative Example 4 A styrene-maleic anhydride copolymer resin (Vicat softening point 120 ° C.) was used as the resin forming the foam, and a rubber-modified styrene-maleic anhydride copolymer resin (Vicut was used as the resin forming the film. A laminated foam was obtained in the same manner as in the example except that the softening point of 116 ° C was used. The properties of this laminated foam are shown in Table 1. Next, this laminated foam was molded using the same headliner molding die as in Example 1. Various physical properties of the laminated foam after molding are also shown in Table 1.

Comparative Example 3 A laminated foam was obtained in the same manner as in Example except that the resin forming the foam and the resin forming the film were polystyrene (Vicat softening point 105 ° C.). The properties of this laminated foam are shown in Table 1. Next, this laminated foam was molded using the same headliner molding die as used in the examples. Various physical properties of the laminated foam after molding are also shown in Table 1.

* 1 50 mm x 150 mm from laminated foam and foam after molding
Cut out the test piece, and place the test piece on the center of the test piece (center position between the support parts) by supporting it on two support parts provided at 100 mm intervals on the line 25 mm inside both side edges of 50 mm. ) A load-deflection curve was obtained by applying a load to the front width at a speed of 20 mm / min, and the maximum load on this curve was defined as the maximum bending load.

Incidentally, the vertical and horizontal values in the measured values indicate the measured value of the test piece cut so that the piece of 150 mm is along the extrusion direction of the foam as the vertical value, and the piece of 150 mm is orthogonal to the extrusion direction of the foam. The measured value of the test piece cut along the direction is shown as a horizontal value.

* 2 According to ASTM-D-1621, the test speed was 10 mm, the size of the test piece was 50 mm x 50 mm, and the load required to compress 25% of the thickness of the test piece was measured to obtain 25% compressive strength.

* 3 The beam span is 150 mm x 450 mm from the foam after molding.
Cut out the test piece of 150 mm, and place it on the upper surface of the test piece by supporting it on the two support parts provided at intervals of 300 mm on the line 75 mm inward from both side edges of this test piece.
After stacking the 20 mm thick polyethylene sheets,
The amount of sag of the test piece after heating for 6 hours in a circulation dryer adjusted to 5 ° C ± 2 ° C was shown.

Incidentally, the vertical and horizontal values in the measured values indicate the measured values of the test side obtained by cutting the side of 450 mm along the extrusion direction of the foam as the vertical value, and the side of 450 mm is orthogonal to the extrusion direction of the foam. The measured value of the test portion cut along the direction is shown as a horizontal value. The geometric mean value is also shown in the vertical and horizontal values.

〔The invention's effect〕

As described above, the base material for automobile molding top material of the present invention comprises a biaxially stretched thermoplastic resin film provided on the surface of a foam made of a thermoplastic resin having a Vicat softening point of 115 ° C. or higher. Therefore, it has excellent mechanical strength as well as excellent thermal strength, and has various effects such as no possibility of being deformed due to long-term use in an automobile compartment where temperature changes drastically. In particular, the present invention has a stretching degree of 5 to 5, respectively.
By using a 40% styrene-acrylic copolymer foam and a styrene-acrylic copolymer film with a stretching ratio of 15 to 60% each, it is important as a base material for automobile molding materials. The effect that the characteristic beam span is greatly improved can be obtained.

[Brief description of drawings]

The drawings show an embodiment of the present invention. FIG. 1 shows an embodiment of the base material for automobile molded ceiling material of the present invention. FIG. 2 is a longitudinal sectional view taken along the line I-I, and FIG. Fig. 3 is a schematic sectional view showing the manufacturing process of Fig. 3, and Fig. 3 is a vertical sectional view showing an example of an automobile ceiling material. 1 ... Base material for automobile molding ceiling material 2 ... Foam material 3 ... Thermoplastic resin film

Continuation of front page (72) Inventor Akira Adachi 515-14 Kamiza, Sakura City (56) References JP-A-53-32514 (JP, A) JP-A-57-72830 (JP, A)

Claims (6)

(57) [Claims] 1. A biaxially stretched thermoplastic resin film is provided on the surface of a biaxially stretched foam made of a thermoplastic resin having a Vicat softening point of 115 ° C. or higher, and the thermoplastic resin of the foam is Styrene-acrylic copolymer, the degree of stretching of the foam is 5 to 40%, and the thermoplastic resin of the film is styrene-acrylic copolymer, and the degree of stretching of the film is 15 to 50%, respectively. 60% base material for automobile molding ceiling material. 2. A foamed body which is formed by integrally compressing a cylindrical foamed body obtained by extruding a thermoplastic resin by extruding and foaming it into a flat shape and fusing the inner surface side and stretching it in a biaxial direction. The base material for automobile molding ceiling material according to claim 1. 3. The Vicat softening point of the base resin of the film is 11
The base material for automobile molding ceiling material according to any one of claims 1 to 2, which has a temperature of 5 ° C or higher. 4. The base material for an automobile molding ceiling material according to any one of claims 1 to 3, wherein the film has a thickness of 20 to 250 μm. 5. The base material for automobile molding ceiling material according to any one of claims 1 to 4, wherein the thermoplastic resin forming the film is a rubber-modified styrene-acrylic copolymer resin. . 6. The automobile molding ceiling according to any one of claims 1 to 5, wherein the foaming agent used for extrusion foaming is a mixture of dichlorodifluoromethane and methyl chloride and / or ethyl chloride. Material base material.