JPS6375162A - Fiber sheet molded body - Google Patents

Abstract

(57) [Abstract] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a fiber sheet molded article that is lightweight, has high strength, has excellent formability, heat insulation properties and sound absorption properties, and is particularly useful as a ceiling material for automobiles.

(Prior Art) Cardboard and various resin foams are used for the molded ceiling, which is one of the interior materials of the WJxL. Cardboard is lightweight and inexpensive, but since the only means of shaping it is compression, it has poor formability and cannot be shaped into delicate shapes.

Furthermore, it has the disadvantage of poor shape retention due to its hygroscopic properties. Therefore, resin foams are widely used. For example, JP-A-58-71154 and JP-B-Sho 58-2811 disclose molded ceilings using modified polystyrene foam. Such molded bodies are obtained by foaming resin and molded into the desired shape, so they have excellent shaping properties, and the molded bodies obtained are relatively strong and lightweight, and have excellent VC properties such as heat insulation and heat resistance. . However, since thermoplastic resin is used, the dimensional stability and strength at high temperatures are poor. Furthermore, since closed-cell foam is used to obtain a heat-insulating effect, sound is reflected on the surface, making it impossible to obtain a sufficient sound-absorbing effect. In order to improve the strength of such molded ceilings, reinforcing materials are laminated, and in order to obtain a sound absorption effect, sound absorbing materials are laminated or through holes are provided in the base material (Japanese Patent Application Laid-open No. Publication No. 11947, Japanese Unexamined Patent Publication No. 11947
3-i4074 and Japanese Patent Publication No. 57-60944), the manufacturing process is complicated and costs are high. Another drawback is that the weight of the molded ceiling itself increases, reducing the fuel efficiency of the vehicle.

(Problems to be Solved by the Invention) The present invention solves the above-mentioned conventional drawbacks, is lightweight, has high strength, has excellent formability, heat resistance, heat insulation, and sound absorption, and has high strength and dimensional stability at high temperatures. The purpose of this invention was to provide a fiber sheet molded product that has excellent properties and is particularly suitable for molded ceilings of automobiles.

(Means for Solving the Problems) The gist of the present invention is that a nonwoven fabric base material in which I/C thermoplastic resin expandable fibers are dispersed between fiber materials containing inorganic fibers is heat-compression molded, and the fibers are There exists a fiber sheet molded article in which the materials are bonded together with a melt of the thermoplastic resin foamable fibers.

The fibrous material used for the nonwoven fabric serving as the base material of the molded article of the present invention contains inorganic fibers and, if necessary, organic fibers in a proportion of 75% by weight or less.

Materials for such inorganic fibers include glass and rock cool, while materials for organic fibers include polyethylene,
Examples include polypropylene, polyester, and nylon.

When the content of organic fiber exceeds 751i% by weight, the strength of the obtained molded article decreases. All of these fibers are short fibers with a diameter of 2 to 40 μm and a length of 50 to 2001!9I. If the fiber diameter or edge length is below the above range, the strength of the resulting molded product will be insufficient, and if it exceeds the above two ranges, the shapeability during molding will be poor.

The thermoplastic resin foamable fibers to be mixed with the nonwoven RC fabric are:
A material prepared by kneading a decomposable foaming agent and having the property of foaming when heated to a temperature higher than the decomposition temperature of the decomposable foaming agent is preferably used. Thermoplastic resins include polyethylene, polypropylene, ethylene-vinyl acetate copolymer, polyvinyl chloride, polystyrene, and ABS.
Resin etc. are used. As decomposable blowing agents, inorganic decomposable blowing agents such as sodium bicarbonate, ammonicum carbonate, ammonicum nitrite, and azide compounds, and organic decomposable blowing agents such as azo compounds, nitrone compounds, and sulfonyl hydrazide compounds are used. .

The thermoplastic resin expandable fiber is produced by adding a decomposable foam to the thermoplastic resin using a kneading roll or a kneading extruder at a temperature above the softening temperature of the thermoplastic resin and below the decomposition temperature of the decomposable blowing agent to be kneaded. The blowing agent is kneaded and the mixture is melt-extruded through multiple nozzles at a temperature below the decomposition temperature of the decomposable blowing agent.
It is manufactured by forming it into a fiber using a method such as drawing at high speed.

The maximum expansion ratio during foaming of the thermoplastic resin expandable fiber is 6 times or more, preferably 10 times or more.

If it is less than 6 times, the function as a pin glue to bond the fiber materials in the nonwoven fabric base material to each other during hot pressure la bottom molding of the nonwoven fabric base material, which will be described later, will be insufficient, resulting in a decrease in the strength of the VC molded product. . Although the upper limit of the expansion ratio of the expandable fiber is not particularly limited, the upper limit of the expansion ratio that can be produced by such foam fiber is about 50 times. The material of the thermoplastic resin, the particle size, the type of blowing agent, the content of the blowing agent, etc. are appropriately selected so that the expansion ratio of the expandable fibers is 6 times or more.

Such expandable fibers can be used in an amount of 20 to 12
It is contained in a proportion of 0% by weight. If it is too small, the strength of the molded product obtained will be insufficient, and if it is too large, it will be difficult to adjust the nonwoven fabric base material.

Further, the foamable fibers preferably have a thickness of about 40 μm, and a length of about 2 to 200 mm. If it is larger than the above value, it may be difficult to mix it with fiber materials, but the thickness and length are not particularly limited as long as it is not difficult to mix it.

The nonwoven fabric base material which is the base material of the molded article of the present invention is
It is manufactured using R fibers, foamable fibers, and organic fibers depending on the required VC according to a conventional manufacturing method for nonwoven fabrics. for example,
First, glass fibers, which are commercially available in shapes such as yarn chops and roving chops, are opened. When using organic fibers, VC#-i is also discarded in the same way to form a fixture, and the glass fibers (inorganic edge 14k), foamed fibers, and if necessary organic fibers are thoroughly processed using a card machine or the like. Blend and pressure molding to obtain a nonwoven fabric substrate.

The porosity of such a nonwoven fabric substrate is 92 to 99.5%. If it is less than 92%, even if the expandable fibers are foamed in the heat compression molding process described below, the melt will not be able to sufficiently penetrate between the fiber materials, and as a result, the binder that firmly adheres the fiber materials to each other will fail. The effect cannot be obtained sufficiently. In other words, the strength of the molded product obtained is insufficient. If the porosity is too high, it will be difficult to maintain the shape of the nonwoven fabric, and the strength of the resulting molded product will also decrease. The thickness of the nonwoven fabric base material varies depending on the thickness and density of the intended molded article, but is usually 10 to 100 m, preferably Fil O to 60 ff. If it is less than 10fl, the strength of the entire molded ceiling will be insufficient, and if it exceeds 100ff, it will be difficult for heat to be transmitted to the center during heating, which will be described later, so a large amount of heat will be required.

The nonwoven fabric substrate obtained in this way is cut to an appropriate size, heated, and compression molded using a pair of molds having projections and depressions of a desired shape. The heating temperature at this time needs to be higher than the decomposition temperature of the decomposable blowing agent kneaded into the expandable fibers and the melting point of the thermoplastic resin used in the expandable fibers.

The temperature of the mold during compression molding may be below the melting point of the thermoplastic resin used in the expandable fibers and the organic fibers mixed as needed, but is usually room temperature to 80°C. That's about it. The compression force of compression molding is usually 0.2
~50) l/- and the compression time FiIO ~600 seconds.

In this way, the thickness of the original nonwoven fabric base material is 05~α
Compression molding is performed to a 7-fold range to obtain a fiber sheet molded product. The thickness of the molded body is 1 to 20 ff.

For example, in the case of ceiling materials for automobiles, in the peripheral part where strength is particularly required, the strength is less than α05 times that of the original thick wood. It is compressed to 0.2 to 0.7 times the thickness of the animal.

The peripheral part of such a molded body has a thickness of about 1 to 3 WM, and the central part has a thickness of about #'i4 to 1105r. If K is molded to a thickness of α7 times or more (low density), the strength of the molded product will be insufficient because the foaming, melting, and solidification of the expandable fibers will not sufficiently bond the fiber materials. On the other hand, there is no particular problem if it is less than α05 times, but it is wasteful because it requires a pressure as large as 1t3VC. The porosity of the central portion is about 50% or more, and this type of molded body has excellent sound absorption properties.

A decorative interior material such as a woven fabric, a nonwoven fabric, or a plastic ivy sheet is adhered to the surface VC of the molded object of the automobile ceiling material obtained by such a method. The nonwoven fabric base material and the interior decorative material may be laminated, heated, and compression-molded into one body.

As described above, the fiber sheet molded article of the present invention is obtained by hot-pressure molding a nonwoven fabric base material in which Kumano resin foamable fibers are dispersed between fiber materials containing inorganic fibers. The thermoplastic resin used in the expandable fibers in the nonwoven substrate softens during the heating process and later melts. Further, the decomposable foaming agent contained in the foamable fibers decomposes and gas is generated. For this purpose, it is necessary to cause foaming when the foamable fibers are sufficiently uniformly mixed in the nonwoven fabric base material by heating.
After it has sufficiently penetrated between the fibers, it melts and forms droplets. By compressing this nonwoven fabric base material with a mold, the molten resin derived from the foamable fibers is further promoted to penetrate between the fiber materials, and when the temperature drops, this resin hardens. Acts as a binder to firmly bond fibers together. Since the fibrous materials are fixed to each other by the resin in this manner, it has excellent strength and shape retention. Because inorganic fibers are used, its thermal stability is much higher than that of conventional thermoplastic foams.

The molded article of the present invention is lightweight because it is obtained from a relatively low-density nonwoven fabric base material. The density of the molded body differs depending on its part, but for example, the peripheral part of an automobile ceiling has a high density because it is sufficiently compressed and molded, while the low-density part has elasticity and high sound absorption coefficient.

As described above, since the single molded product has the above-mentioned various excellent properties, there is no need for reinforcing materials, sound absorbing materials, etc. that were conventionally required. Therefore, the manufacturing process for automobile ceilings is simplified, and the weight of the ceiling itself is also reduced.

Next, how the molded article of the present invention is manufactured will be explained with reference to an example of FIGS. 1 and 2.

In FIG. 1, fiber supply container 1. A predetermined amount of the inorganic fibers 2 and foamable fibers 3 stored in IIK are supplied onto the belt conveyor 21. The inorganic fibers 2 and foamable fibers m3 are supplied to a card machine 5 and mixed under sufficient pressure to form a continuous nonwoven fabric base material 6, which is wound up by a winder 7. The six rolled up nonwoven fabric base materials are cut into desired shapes and sizes.

In FIG. 2, the cut nonwoven fabric base material 6 and the interior decoration material 8 are laminated to form a laminate 10, and this laminate 10 is led onto a belt conveyor 22 to a heating furnace 51, where it is heated. The laminate 10 is compression-molded using a molding die 12 to form a #&fiber receipt molded body.

(Example) The present invention will be explained below using examples.

Example 1) Preparation of molded body As inorganic fiber, 90 parts by weight of glass fiber with diameter 13 μm 1 fiber length 5 to 20 cs, as organic Fa fiber, diameter 18 μm
10 parts by weight of polypropylene fibers with a fiber length of 5 to 20 m1, 100 parts by weight of polypropylene resin and 10 parts by weight of azodicarbonamide as foamable fibers, and a diameter of 1
5 μm 1 length 5-20 countries polypropylene foam fiber 5
Using the device shown in Figure 1, using 0 parts by weight, the width was 1300 mm.
A roll-shaped nonwoven fabric having a length of 30 m and a length of 30 m was produced. Width 1150111, length 1400+11'2F
K cutting was carried out, the above-mentioned interior decoration material of the same size was laminated thereon, and the periphery was pinched with a clamp.

This laminate was heated as shown in Fig. 2 for 3 minutes in a hot air heating furnace at 180°C, and then immediately compression-molded for 1 minute using a mold at a temperature of 30°C at a compression force of I kg/-. did. This mold was designed to have a minimum thickness of 1MIR and a maximum thickness of 8.0IOIK, and the obtained molded product almost corresponded to the shape of this mold.

(B) Performance evaluation of molded body After holding the molded body obtained in the prison term in a hot air open at 95°C for 4 hours, the original thickness of the molded body was Z9n,
The original thickness is 81! r1! The thickness of the portion was measured and the rate of change (%) was calculated. Separately, from the molded body obtained in Section 1, the thickness was 8rtttr, the width was 301!7w, and the length was 150mm.
A test piece of No. 0 was cut out and the bending strength was evaluated.

First, the test piece was placed on a pair of supports spaced apart from each other by 10 on. Next, force is applied to the center of the test piece at a speed of Know/min. Then, the weight of the sample piece when it was bent was measured.

Furthermore, from the molded body obtained in the prison term, a thickness of gfl and a width of 5
A sample piece with a length of 50 mm was cut out, and the sound absorption coefficient at 1000 Hz was measured using the reverberation chamber method.

The results are shown in Table 1. In the bending strength section of Table 1, ○ indicates 10Kg/an or more, Δ indicates Fi9.
9 to 6 Shun/-, and × mark #'i5.9Kg/cll
Indicates i or less.

The results of Examples 2 to 7 and Comparative Examples 1 to 6 are also included in the first
Shown in the table.

Example 2 Expandable fibers are L&fiber material (inorganic fibers + organic fibers) 111
The process is the same as in Example 1 except that it was used at a ratio of 11'5% to fi.

Example 3 The same as Example 1 except that the expandable fibers were used at a ratio of 25% based on the weight of the fiber material.

Example 4 This was the same as Example 1 except that the thickness of the nonwoven fabric base material was 601 fl+.

*Zettai 5 Same as Example 1 except that the porosity of the nonwoven fabric base material was 93% and the thickness was 12%.

Example 6 The same as Example 1 except that the porosity of the nonwoven fabric base material was 99.49h1 and the thickness was 60M.

-* Absolutely 7 The weight ratio of glass tR fiber and polypropylene fiber is 1:1
This example is the same as Example 1 except for the above.

Comparative Example 1 Completely the same as the Fip example except that no foamable fiber was mixed.

Comparative Example 2 Comparative Example 2 Same as Fi Example 1 except that organic fiber was used in the 100-fold area without using inorganic fiber.

(Effects of the Invention) Since the fiber sheet molded article of the present invention has the above-described structure, it is lightweight, has high strength, and has excellent formability, heat resistance, heat insulation, and sound absorption properties, and is suitable for use in automobile ceiling materials. Iroto is suitable,
Reinforcing materials, cushioning materials, and
Sound-absorbing materials are no longer needed and can be supplied at low cost, and the ceiling itself is also lighter, reducing fuel consumption.

The wood fiber sheet molded product is used not only for JIE ceiling materials, but also for ceiling materials for houses and ships, and building materials for fire-heating construction materials.

[Brief explanation of the drawing]

Figures 1 and 2 are explanatory diagrams of the process of manufacturing a molded body for zero firing. Explanation of symbols 1.11...Fiber supply container, 2...Inorganic fiber, 3.
... Foaming fiber 1.5... Card arm shin, 6... Nonwoven fabric base material, 7... Winding machine, 8... Interior decorative material, 10
...Laminated body, 21...Belt conveyor, 51...
heating furnace.

Claims (2)

[Claims] 1. A nonwoven fabric base material in which thermoplastic resin foamable fibers are dispersed between fiber materials containing inorganic fibers is heat compression molded, and the fiber materials are bonded with a melt of the thermoplastic resin foamable fibers. Sheet molded body. 2. The fibrous sheet molded article according to claim 1, wherein the fibrous material contains organic fibers in a weight fraction of 75% by weight or less.