JPH0611936B2 - Method for producing composite material for thermoforming - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for producing a composite material having excellent thermoformability, particularly a composite material preferably used as a ceiling material for automobiles.

[Conventional technology]

Conventionally, cardboard, glass fiber reinforced thermosetting resin sheet, etc. have been used as the base material for molded ceiling material, which is one of the interior materials for automobiles.However, cardboard has poor heat shaping properties and no sound absorption. In addition, since it is hygroscopic, it has a drawback that it absorbs water and becomes heavy when used for a long period of time, and the thermosetting resin sheet has low productivity and poor heat shaping property and is heavy. Had.

Various proposals have been made to solve these drawbacks. For example, Japanese Utility Model Laid-Open No. 58-15035 discloses a laminate in which a glass fiber reinforced thermoplastic resin film is laminated on both sides of a styrene resin foam sheet. An automobile interior material in which a soft synthetic resin foam and vinyl chloride leather are sequentially laminated on one surface is described.

The above-mentioned interior material has excellent heat resistance and mechanical strength, but it is relatively heavy, has no sound absorption, and has the drawbacks of high cost.

Further, JP-A-60-83832 discloses an automobile ceiling material in which a foam layer and a skin are laminated on a resin layer on a base material in which a thermoplastic resin layer is laminated on both sides of a glass fiber layer.

The base material is thin, has high mechanical strength and excellent heat formability, but lacks sound absorbing properties, heat insulating properties, etc., and it is necessary to laminate a foam or the like as an automobile ceiling material, As a whole, the heat formability was insufficient.

[Problems to be Solved by the Present Invention]

In view of the above drawbacks, the present invention is lightweight and heat resistant, mechanical strength,
An object of the present invention is to provide a method for producing a thermoforming composite material which has excellent sound absorption properties, excellent heat shaping properties, high productivity, low cost, and particularly suitable for use as an automobile ceiling material. .

[Means for solving problems]

The mat-like material used in the present invention comprises inorganic fibers and at least one resin component selected from the group consisting of thermoplastic resin fibers and thermoplastic resin powders.

Examples of the inorganic fibers include glass fibers and rock wool, and the length thereof is preferably 5 to 200 mm from the viewpoint of forming a mat-like material, and 70% by weight or more of 50 mm or more is contained. More preferable. Further, the thickness is preferably 5 to 30 μm, more preferably 7 to 20 μm because the mechanical strength decreases as the thickness decreases, and the bulk density decreases as the thickness increases.

Examples of the thermoplastic resin fibers and thermoplastic resin powders include fibers and powders made of thermoplastic resins such as polyethylene, polypropylene, saturated polyester, polyamide, polystyrene, polyvinyl butyral and polyurethane. The length and the diameter of the thermoplastic resin fiber are preferably 5 to 200 because the formability when forming a mat-like material by mixing with the inorganic fiber is excellent.
mm is preferred, more preferably 20-100 mm,
The thickness is preferably 3 to 50 μm, more preferably 20 to
It is 40 μm. The diameter of the thermoplastic resin powder is preferably 50 to 100 mesh when added in powder form,
It may be smaller when it is dispersed in a poor solvent or added as an emulsion.

The amount of the inorganic fiber and the resin component added is such that when the ratio of the inorganic fiber is large, the ratio of the resin component is small and the adhesive points between the inorganic fibers are small, and conversely when the ratio of the inorganic fiber is small, the ratio of the resin component is small. Since it increases, the mechanical strength and rigidity decrease together, so that the range of 1: 5 to 10: 1 (weight ratio) is preferable.

If the density of the mat-like material increases, it becomes heavier, and if it decreases, the mechanical strength decreases, so 0.01-0.2 g / cm ³
Is preferable, and more preferably 0.03 to 0.07 g / cm ³ .

Any method may be adopted as the method for producing the mat-like material, and examples thereof include a method of supplying inorganic fibers and a resin component to a card machine to defibrate and mix them to produce a mat-like material.

The thermoplastic resin powder may be added after the production of the mat-like material, or may be dispersed in a poor solvent or made into an emulsion and sprayed on the mat-like material, or the mat-like material may be dipped.

Needle punching may be carried out in order to improve the mechanical strength of the mat-like material. Needle punching is preferably carried out at 1 to 3 places per cm ² .

The plate-like body used in the present invention has a property that the above resin component is fused in a molten state but does not adhere in a non-fused state. For example, a glass fiber reinforced polytetrafluoroethylene sheet, the surface of which is polytetrafluoro Examples thereof include a press plate processed with ethylene and a polyester sheet whose surface is treated to be released.

In the present invention, the plate-like bodies are laminated on both surfaces of the mat-like material, and the resin component is melted by heating it to a temperature equal to or higher than the melting temperature of the resin component and compressed under pressure.

As the heating method, any method may be adopted, and examples thereof include a hot air heating method, a radiant heating method using an infrared heater, a far infrared heater and the like.

The heating and the laminating of the plate-shaped bodies may be performed in either order, and may be laminated after heating or may be heated after laminating.

Further, any method may be adopted as the compression under pressure, and examples thereof include a pressing method and a rolling method. The pressing pressure is preferably 0.1 to 20 kg / cm ² , and the compression time may be several seconds. When compressing with a roll, it is preferable to set the space between the rolls to 4/5 to 1/20. When both the press and the roll are compressed, it is preferable that they are heated to a temperature equal to or higher than the melting temperature of the resin component. In the present invention, the mat-like material in which the plate-like materials are compressed and compressed is decompressed, the plate-like material is expanded with the resin component melted, and the mat-like material is cooled after the thickness is increased. To be done.

The molten resin component is impregnated in the inorganic fiber when compressed under pressure. Next, when the pressure is released, the mat-like material tries to recover to the original thickness, but the inorganic fiber is once crushed and thus does not recover sufficiently. Therefore, if the plate-shaped body is expanded with the resin component melted, the mat-shaped material is fused to the plate-shaped body, so that the thickness is recovered and the volume becomes bulky. At this time, since the resin component is melted, the inorganic fibers and the bonded portion are not broken. Further, the expanding method may be carried out, for example, by holding both ends of the plate-shaped body, or may be pulled in the opposite direction by vacuum suction.

The mat-like material that has been expanded and made bulky is then cooled, but the cooling may be allowed to cool or blow cold air. When the plate-shaped body is peeled off after the resin component is solidified by cooling, a thermoforming composite material is obtained.

A thermoplastic resin film may be laminated on the mat-like material before heating.

Examples of the thermoplastic resin film include thermoplastic resin films such as polyethylene, polypropylene, polystyrene, and saturated polyester.

The thickness of the thermoplastic resin film becomes heavier as it becomes thicker, and the mechanical strength becomes lower as it becomes thinner, so that it is preferably 50 to 500 μm, more preferably 70 to 300 μm.

In order to shape the thermoforming molten material obtained by the production method of the present invention, reheating to a temperature above the melting temperature of the resin component, compression molding with a press or the like may be performed, and it can be used as a ceiling material for automobiles. At the time of compression molding, a cosmetic skin material such as vinyl chloride leather or a non-woven fabric may be laminated and shaped.

〔Example〕

 Next, examples of the present invention will be described.

Example 1 Glass fibers having a length of 40 to 200 mm and a diameter of 9 to 13 μm and polyethylene fibers having a length of 51 mm and a diameter of 30 μm (melting temperature 135 ° C.) were supplied to a card machine at a ratio of 2: 1 (weight ratio) to mix fibers. A mat-like product having a thickness of 10 mm and a weight of 800 g / m ² was obtained by needle punching at 2 points per cm ² . Glass fiber reinforced polytetrafluoroethylene sheet (thickness 150μ
m) is laminated and heated at 200 ° C. for 3 minutes, and the clearance is 1.3 mm.
Vacuum suction of glass fiber reinforced polytetrafluoroethylene sheet from both sides at a rate of 0.5 mm / sec, keeping at 00 ° C.
The thickness of the mat-like material was recovered to 9 mm, followed by air cooling for 3 minutes, and then the sheet was peeled off to obtain a thermoforming composite material.

The obtained composite material was heated in an oven at 200 ° C. for 2 minutes and then compressed in a mold at 30 ° C. for 1 minute with a compression force of 1 kg / cm ² to obtain a molded body. The mold had a minimum wall thickness of 3.0 mm, a maximum wall thickness of 8.0 mm, and a concave portion with a radius of curvature of 5 mm. The obtained molded product had a length of 1400 mm and a width of 1150 mm.

The obtained molded body was supplied to a hot air dryer set at 95 ° C., the four sides were held, and the heat resistant displacement amount (hanging distance) after 24 hours was measured. Also, thickness 6mm, width 50mm, length 1
A rectangular sample piece of 50 mm is prepared and placed on a pair of supports arranged at intervals of 100 mm.
The bending strength was obtained by measuring the load when the sample piece was bent by pressing at a speed of mm / min. Furthermore, by the vertical incidence method, 15
The sound absorption coefficient at 00 Hz was measured.

Further, the thermoformability (curvature radius of the portion of the molded body corresponding to the concave portion of the mold having a radius of curvature of 5 mm) was measured and shown in Table 1.

Example 2 In the same manner as in Example 1, glass fibers and polyethylene fibers were mixed and formed into a mat-like material, and needle-punched at 1 point per 1 cm ² to obtain a mat-like material having a thickness of 10 mm and a weight of 500 g / m ² . And a thickness of 150 on both sides of the obtained mat-like material.
A polyethylene sheet (melting temperature: 135 ° C.) having a thickness of μm was laminated to obtain a laminated sheet. Using the obtained laminated sheet, a 9.0 mm-thick composite material for thermoforming was obtained in the same manner as in Example 1 to obtain a molded body.

The physical properties of the obtained molded product were measured in the same manner as in Example 1 and the results are shown in Table 1.

Example 3 Using the mat-like material obtained in Example 2, a thermoformable composite material having a thickness of 9 mm was obtained in the same manner as in Example 1, and a polyethylene having a thickness of 150 μm was formed on both sides of the obtained composite material. After laminating the films, a molded product was obtained in the same manner as in Example 1 and the physical properties were measured. The results are shown in Table 1.

Comparative Example Roll compression was performed in the same manner as in Example 1 and then the mixture was allowed to stand for air cooling to obtain a composite material for thermoforming having a thickness of 4.3 mm. A molded body was obtained using the obtained composite material in the same manner as in Example 1 and the physical properties were measured. The results are shown in Table 1. The bending strength was measured with a sample having a thickness of 4.3 mm.

[Effects of the Invention] The method for producing the thermoforming composite material of the present invention is as described above, and it is bulky, lightweight, and has excellent heat shapeability, and also has excellent heat resistance, mechanical strength, sound absorption, and the like. A low-cost composite material for thermoforming can be easily manufactured.

The obtained composite material for thermoforming has good thermoformability because the thermoplastic resin fiber or powder is melted and the glass fiber is effectively adhered to the composite material, and it is suitable for use in automobile molding ceilings and the like.

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Claims (1)

[Claims] 1. A mat-like material comprising inorganic fibers and at least one resin component selected from a thermoplastic resin fiber and a thermoplastic resin powder. In the state, laminated plate-like bodies which are not adhered to each other, are heated to a temperature not lower than the melting temperature of the resin component to cause the resin component to be melted under pressure and compression, and then decompressed. A method for producing a thermoformed composite material, which comprises expanding a sheet, increasing the thickness of a mat-like article, and then cooling.