JPH01306663A - Production of formed fiber material for thermo-forming - Google Patents

Abstract

PURPOSE:To obtain the subject formed material suitable for the ceiling material of automobile, by laminating plural layers of inorganic fiber mats interposing thermoplastic resin films therebetween, pressing under heating at a temperature higher than the melting point of the fiber, releasing the pressure to increase the thickness and cooling the product. CONSTITUTION:(A) Inorganic fibers having length of preferably 5-200mm (e.g., glass fiber) are opened to form a mat with, e.g., a carding engine. Two or more layers of the mats A are alternately laminated with (B) a thermoplastic resin film (e.g., polyethylene film) and the laminate is pressed under heating at a temperature higher than the melting point of the component C, the pressure is released to increase the thickness of the laminate and the product is cooled to obtain the objective formed material.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a method for producing a thermoformable fiber molded article suitable as a ceiling material for an automobile.

(Conventional technology) Automotive ceiling materials are lightweight, rigid, heat resistant, sound absorbing,
Materials with excellent properties such as heat formability are required.

As an example of this type of material, Japanese Patent Application Laid-Open No. 60-83832 discloses an automotive ceiling material in which synthetic resin layers such as polyethylene are formed on both sides of an inorganic fiber layer such as glass fiber. However, such molded bodies have problems, particularly in that they have low bending strength and do not have sufficient sound absorbing properties, making them unsatisfactory as ceiling materials for automobiles.

(Problems to be Solved by the Invention) The present invention solves the above-mentioned problems, and its purpose is to provide lightweight, rigid, heat-resistant, heat-formable, bending strength, and sound-absorbing properties. The object of the present invention is to provide a method for producing a thermoformable fiber molded article which is excellent and suitable as a ceiling material for automobiles.

(Means for Solving the Problems) In the present invention, first, a mat-like material mainly composed of inorganic fibers and a thermoplastic resin film are alternately laminated so that at least two layers of the mat-like material are present.

The above inorganic fibers include glass fiber, rock wool,
Ceramic fibers, carbon fibers, etc. are mentioned, and the length thereof is preferably 5 to 200 mm from the viewpoint of formability of the mat-like product, and it is more preferable that 70% by weight or more of fibers of 50+nn+ or more are contained. Further, the thickness is preferably 2 to 30 μm, more preferably 7 to 20 μm, because as the thickness becomes thinner, the mechanical strength decreases, and as it becomes thicker, it becomes heavier and the bulk density decreases.

Thermoplastic resin fibers may be mixed with the above inorganic fibers. When such thermoplastic resin fibers are mixed, the mat-like material becomes bulky and matting becomes easy. Such thermoplastic resin fibers include polyethylene fibers, polypropylene fibers, polyester fibers, polyamide fibers, polystyrene fibers, etc., and the length is preferably 5 to 200 mm, more preferably 20 to 100 m, and the thickness is is preferably 3 to 50 μm, more preferably 20
~40 μm.

Such thermoplastic resin fibers may be melted in the heat compression process of the present invention to become a binder for inorganic fibers;
There are cases where the inorganic fibers are mixed without being melted, but there is no problem in either state.

Moreover, a thermoplastic resin powder may be mixed with the above-mentioned inorganic fiber. Such a thermoplastic resin powder is a resin having a melting point lower than that of the resin constituting the thermoplastic resin film among the same resins as the thermoplastic resin film to be laminated on the mat-like material, and generally has a mesh size of 50 to 100. Powder is used. Such thermoplastic resin powder is melted in the heat compression step of the present invention and becomes a binder for inorganic fibers.

The density of the mat-like material should be 0.01 to 0.2 g, as the larger the mat, the heavier it becomes, and the smaller the density, the lower the mechanical strength.
/c is preferable, more preferably 0.03 to 0.07
g/crd. In addition, as the thickness of the mat-like material becomes thinner, the mechanical strength decreases, and when it becomes thicker, it is difficult for heat to be transmitted to the center during heating, and a large amount of heat is required.
The range is preferably 4 to 1 mm for automotive ceiling materials.
2 mm is preferred.

Any method may be used to produce the above-mentioned mat-like material. For example, inorganic fibers and resin components such as thermoplastic resin fibers and thermoplastic resin powder are supplied to a card machine, defibrated and mixed, and then Accordingly, there is a method of producing a mat-like material by applying needle punching. Needle punch is 1cf
It is preferable to perform this at 1 to 30 locations per I. When a thermoplastic resin powder is mixed, this powder may be added after the mat-like material is produced, or an emulsion or suspension of the powder may be dispersed.

Examples of the thermoplastic resin film laminated on the mat-like material include polyethylene, polypropylene, polystyrene, polyvinyl butyral, polyurethane, polyvinyl chloride,
Examples include films made of thermoplastic resins such as polyvinyl acetate and polyester. The thickness of such a film is 3
A suitable thickness is 0 to 200 μm.

The mat-like material and the thermoplastic resin film are laminated one layer at a time alternately so that there are at least two layers of the mat-like material, but in this case, five or more layers are stacked so that the thermoplastic resin film is the outermost layer on both sides. Lamination is preferred. Further, it is preferable that such a laminate is needle punched at 1 to 30 locations per ICTII. This needle punching causes the mat-like materials to intertwine with each other, thereby improving the compressive strength of the resulting fiber molded product.

Next, in the present invention, the laminate of the mat-like material and the thermoplastic resin film is compressed while being heated to a temperature equal to or higher than the melting point of the thermoplastic resin film.

Any heating method may be employed, such as a hot air heating method, a radiant heating method using an infrared heater, a far-infrared heater, or the like. Furthermore, any compression method may be employed, such as a pressing method, a method of compressing with a roll, and the like. Compression pressure is 0.1-2
The range of 0 kg/ci is preferable, and the compression time is 5 to 30
Seconds are enough. This heating and compression reduces the thickness of the mat-like material. During compression, it is preferable to heat the press or roll to a predetermined temperature.

The above-mentioned heating and compression may be performed in this order in separate steps, but if a press is used, heating can be performed with this press and compression can be subsequently performed with the same press. This heating and compression melts the thermoplastic resin film and reduces the thickness of the mat-like material, and this melt is impregnated into the gaps between the inorganic fibers and becomes a binder for the inorganic fibers.

Thereafter, in the present invention, the pressure is released, the thickness of the mat-like material is increased, and the mat-like material is cooled.

When the pressure is released in this way, the compressed mat-like material naturally tries to recover its original thickness and increases in thickness. When this amount of recovery is insufficient or takes a long time, the thickness is increased by blowing heated air into the inside or separating both surfaces by vacuum adsorption.

In particular, in the present invention, during compression, a pair of sheets or plates, such as glass fiber-reinforced polytetrafluoroethylene, that adheres to both surfaces of the laminate when the thermoplastic resin film is molten but does not adhere when it is not molten. Platy sheets are stacked, and when the pressure is released, the sheet or plate is held at both ends or pulled in the opposite direction by vacuum suction, thereby making the mat-like material adhere to the sheet or plate. Preferably, a method is adopted in which the sheet or plate-like material is expanded in the thickness direction in the state, the thickness is recovered and increased, and the sheet or plate-like material is peeled off from the mat-like material after cooling. In this case, productivity can be improved by cooling the sheet or plate while pulling it in the opposite direction.

The thickened mat-like material may be cooled by leaving it to cool or by blowing cold air onto it. In this way, a thermoformable fiber molded article is obtained.

In order to shape the thermoformable fiber molded article obtained by the method of the present invention into the final shape, it is reheated to a temperature higher than the melting point of all the thermoplastic resin components contained in the molded article,
Compression molding is performed using a cooling press mold, etc. During this compression molding process, polyethylene foam, polypropylene foam, polyvinyl chloride foam,
Cosmetic skin materials such as woven fabrics, non-woven fabrics, and vinyl chloride leather may be laminated and integrally shaped with or without intervening closed-cell or open-cell foams such as polyurethane foams.

(Function) In the present invention, when heating and compression are performed with the film laminated between at least two layers of the mat-like material, the thickness of the mat-like material decreases, and the molten resin of the film is transferred between the two layers. It is well dispersed in both mat-like materials, and is widely impregnated throughout the inorganic fibers constituting both mat-like materials.

After that, when the pressure is decompressed, the thickness of the mat-like material is increased, and the mat-like material is cooled, the inorganic fibers that make up the mat-like material are dispersed in a bulky manner, and the inorganic fibers are partially firmly bonded by the molten resin, creating a large number of voids throughout the material. A fiber molded article for thermoforming is obtained.

(Example) Examples and comparative examples of the present invention are shown below.

Index ± Glass fiber (fiber thickness 9-13 μm, fiber length 50-6
0mm) 75% by weight and high density polyethylene fiber (fiber thickness 6 denier, fiber length 51M, melting point 135°C) 25
% by weight and defibrated using a card machine to form a cotton-like material, which was needle punched at 10 locations per 1 c+fl to produce two mat-like products of 250 g/n (weight).

Using two sheets of the above mat-like material and three sheets of high-density polyethylene film (thickness 100 μm, melting point 135°C), five layers of the mat-like material and the film were laminated alternately, and 1 c.
++ Needle punch 10 places per 1, thickness 10
A laminate of 800 g/rtf in mm was formed.

Glass fiber-reinforced polytetrafluoroethylene plate sheets were layered on both sides of this laminate, heated at 200°C for 3 minutes, and rolled at a speed of 10 cm/min. 1I1
Compressed to 1 thickness. Thereafter, while maintaining the temperature at 200°C, the above plate-like sheet was pulled in the opposite direction by vacuum suction, and the thickness was increased to 9 cylinders with the mat-like material adhered to the plate-like sheet, and after cooling, the above-mentioned The plate-like sheet was peeled from the mat-like material to obtain a thermoformable fiber molded article.

The above molded body was heated in a hot air oven at 200°C for 2 minutes, then taken out, and placed in a mold at 30°C to produce 1 kg/
Compression molding was performed for 1 minute at a pressure of ci to give the final shape. The obtained shaped body has a length of 1400 mm and a width of 1150 nm.
It was un.゛The above mold has a minimum wall thickness of 3.0 mm,
The maximum thickness part is designed to be 8.0 mm, and it has a concave part with a radius of curvature of 5 mm.The radius of curvature (R) of the part corresponding to this concave part is measured to evaluate thermal formability. did.

The above shaped molded article was held on all four sides in a hot air oven at 85° C., and the amount of thermal displacement (distance of hanging) was measured after 24 hours. Further, a sample piece having a thickness of 5 mm, a width of 50 mm, and a length of 150 mm was cut from the above-described molded body, and the bending strength was evaluated according to JIS-K 7211. Furthermore, from the molded body, a thickness of 8 mm and a diameter of 90 m was obtained.
A sample piece of m was cut out, and the sound absorption coefficient at 1' and 5 KHz was measured by the normal incidence method according to JIS A 1405. The results are shown in Table 1.

In addition, 50% by weight of the same glass fiber as in the example and 50% by weight of the same high-density polyethylene fiber as in the example were mixed, defibrated using a card machine to form a fluff, and needle punched at 10 points per cnl. , 600 g/bo mat-like material 1
I created one.

One sheet of the same high-density polyethylene film as in the example was laminated on both sides of one sheet of the above mat-like material, and 1 cffl
Needle punching was performed at 10 locations per sample to form a laminate having a thickness of 10 mm and a weight of 800 g/rrf.

The subsequent steps were carried out in the same manner as in the example. The results are shown in Table 1.

A high-density polyethylene film (thickness 100 μm,
(melting point: 135°C), and this laminate was heated to 20°C.
After heating at 0°C for 2 minutes, it was placed in the same mold at 30°C as in the example and compressed for 1 minute at a pressure of 1 kg/c+fl to obtain a fiber molded article.

In this fiber molded article, the melt of the film remained on the surface of the mantle-like article without being impregnated to a large extent. This fiber molded article was evaluated in the same manner as in the examples.

The results are shown in Table 1.

Table 1 (Effects of the Invention) Since the method of the present invention is configured as described above, the inorganic fibers are partially strongly bonded to each other by the molten resin that is widely distributed as a whole, and a large number of inorganic fibers are bonded throughout the whole. An inexpensive thermoformable fiber molded article having voids can be easily obtained.

This fiber molded article for thermoforming is bulky, and because the inorganic fibers, voids, and molten resin are widely distributed as a whole and are not concentrated in one place, it is lightweight, and has excellent rigidity, heat resistance, sound absorption, and heat shaping properties. It has excellent bending strength and sound absorption properties, and can be suitably used in ceiling materials for automobiles, as well as in many other fields such as ceiling materials for houses and ships, and building materials.

Claims (1)

[Claims] 1. A mat material mainly composed of inorganic fibers and a thermoplastic resin film are laminated alternately so that there are at least two layers of the mat material, and then compressed while heated to a temperature equal to or higher than the melting point of the thermoplastic resin film. A method for producing a fiber molded article for thermoforming, characterized in that the mat-like material is then decompressed, the thickness of the mat-like material is increased, and the material is cooled.