JPH0827654A - Production of thermally moldable composite fiber material - Google Patents

Abstract

PURPOSE:To obtain a thermally moldable composite fiber material capable of producing an inorganic fiber mat having little variation of mechanical strength and especially improved flexural strength. CONSTITUTION:This thermally moldable composite fiber material is produced by applying needle punching on an inorganic fiber mat and impregnating the punched inorganic fiber mat with a thermoplastic resin in a fused state. The needle punching is performed using the following needle: the diameter (D) of a blade 10 is 0.4-0.65mm; the total of kick-up height (H) and stroke depth (S) of a barb 11 is 0.02-0.18mm; and the space (L) between barbs 11 in the same line is 4-8mm.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a thermoformable fiber composite material, which makes it possible to obtain a molded article having improved bending strength.

[0002]

2. Description of the Related Art A method for producing a thermoformable fiber composite material by subjecting an inorganic fiber mat to needle punching and melt-impregnating the inorganic fiber mat with a thermoplastic resin is known (for example, Japanese Patent Application Laid-Open No. 64-64). -77664 and JP-A-2-80652).

This type of thermoformable fiber composite material is lightweight, has good mechanical strength, cushioning properties, sound absorbing properties, heat resistance and heat shaping properties, and is suitable for use as a core material for automobile ceiling materials, for example. Used and has a wide range of other uses.

[0004]

In the inorganic fiber mat used in the above-mentioned conventional method, since the inorganic fibers are highly oriented in the thickness direction by needle punching, the obtained thermoformable fiber composite material is particularly compressed. Strength is improved.

However, when the thermoformable fiber composite material having such improved compressive strength is thermoformed into a desired shape by using a press die, the inorganic fibers bound by the thermoplastic resin are bound together. There is a drawback that the parts are broken, and as a result, the bending strength of the resulting molded article is reduced.

Further, in order to increase the mechanical strength of the inorganic fiber mat, strong needle punching is applied, which causes a large variation in the basis weight of the inorganic fiber mat.
As a result, there is a drawback that the mechanical strength of the thermoformable fiber composite material and the molded product thereof will vary greatly.

The present invention is intended to solve the above problems, and an object of the present invention is to provide a molded product having a small variation in mechanical strength of an inorganic fiber mat, and in particular, a molded product having improved bending strength. It is to provide a method for producing a moldable fiber composite material.

[0008]

[Means for Solving the Problems] The above object is to subject the inorganic fiber mat to needle punching and to melt-impregnate the inorganic fiber mat with a thermoplastic resin to produce a thermoformable fiber composite material. 0.4 to 0.65 mm, the sum of the barb kick-up height and throat depth is 0.
This can be achieved by needle punching the inorganic fiber mat with a needle of 02-0.18 mm and barb spacing in the same row of 4-8 mm.

As the inorganic fiber mat used in the present invention, a glass fiber mat or a rock wool mat is used. These inorganic fiber mats are manufactured by a known method. For example, it can be obtained by supplying glass fiber or rock wool to a card machine to defibrate it, and stacking the fibers into a band to form a cotton-like material.

In this case, the glass fiber and rock wool are
A fiber having a fiber thickness of 3 to 30 μm and a fiber length of 3 to 200 mm is used, and the basis weight of the obtained inorganic fiber mat is 300.
An amount of up to 1000 g / m ² is suitable.

In the present invention, the inorganic fiber mat is needle punched. The needle used for this needle punch is of the same type as the needle conventionally used for this kind of needle punch, but as shown in FIG. 1, for example, the blade portion of the needle (the tip portion having a barb).
The size of the needle is different from that of the conventional needle, and the needle that satisfies a specific condition is used.

That is, FIG. 1A is a perspective view showing an example of a blade portion of a needle used in the present invention.
(B) is a sectional view taken along the line I-I of FIG. 1A, in which the diameter (D) of the blade 10 is 0.4 to 0.65 mm, the kick-up height (H) of the barb 11 and the throat depth. A needle having a sum of (S) and 0.02 to 0.18 mm and a barb interval (L) in the same row of 4 to 8 mm is used.

The sectional shape of the blade 10 is generally triangular as shown, but may be circular or quadrangular. The rows of barbs 11 provided on the blade 10 are generally three rows in the length direction. Also, barb 1
1 is generally three per row, and the barbs 11 in each row are
Generally, they are provided at positions displaced from each other in the length direction without being coincident with each other in the circumferential direction. However, it is not limited to these.

In such a specific needle, the blade 10 is thinner, the degree of catching of the barb 11 is smaller, and the pitch of the barb 11 is wider than that of the conventional needle. It has been found that a thermoformable fiber composite material having a small variation in the mechanical strength of the fiber mat and particularly an improved bending strength can be obtained.

In addition, except that the above specific needle is used,
Needle punching is performed under the same conditions as in the past. For example, the needle density of the needle punch is 1 to 10 as in the conventional case.
About 0 needles / cm ² is preferable, and the needle depth is the same as the conventional one.

A thermoplastic resin is melt-impregnated into the inorganic fiber mat thus obtained. As the thermoplastic resin, polyethylene, polypropylene, saturated polyester, polyamide, polystyrene, polyvinyl butyral or the like is used.

A known method is employed to melt-impregnate the inorganic fiber mat with the thermoplastic resin. For example, by laminating a thermoplastic resin sheet on the above-mentioned inorganic fiber mat, spraying a thermoplastic resin powder, or impregnating an emulsion of a thermoplastic resin, and heating and pressing this, the thermoplastic resin is melted in the inorganic fiber mat. A method of impregnating and then releasing the compression force to restore the thickness is adopted.

In addition, when manufacturing the inorganic fiber mat,
The thermoplastic resin fibers are mixed with the inorganic fibers to make a fiber mat, and the fiber mat is needle punched as described above,
By heating and pressing this, the thermoplastic resin fibers in the fiber mat are melted and impregnated, and then the compression force is released,
A method of restoring the thickness is adopted.

It is also possible to combine two or more of the above-mentioned known methods to melt-impregnate the inorganic fiber mat with the thermoplastic resin.

The weight ratio of the inorganic fiber mat and the thermoplastic resin melt-impregnated into the mat is preferably set in the range of 5: 1 to 1: 5. When the amount of the thermoplastic resin is small, the bonding strength between the inorganic fibers is reduced and the mechanical strength is lowered, and conversely, when the amount of the inorganic fibers is reduced, the heat resistance is lowered.

Thus, the thermoformable fiber composite material is manufactured. In order to obtain a molded article using this thermoformable fiber composite material, first, the thermoformable fiber composite material is softened by heating, put into a press die of a desired shape and pressed, and thermoformed into a desired shape. To make a molded product.

At this time, on the surface of the thermoformable fiber composite material,
Surface materials such as cloth, leather, and vinyl chloride leather can be laminated and integrally molded. Alternatively, a cushion material such as a foam sheet may be interposed between the thermoformable fiber composite material and the surface material to integrally form the material.

[0023]

[Function] The blade diameter is 0.4 to 0.65 mm, and the sum of the barb kick-up height and the throat depth is 0.02 to
A needle having a barb spacing of 0.18 mm and a barb spacing of 4 to 8 mm in the same row has a narrower blade, a smaller degree of barb hooking, and a wider barb spacing than conventional needles.

Therefore, with such a specific needle,
When the inorganic fiber mat is subjected to needle punching, the resulting inorganic fiber mat has entangled fibers, is bulky and has a smooth surface. In addition, the fibers inside the mat are less likely to be spread or hardened, which reduces the variation in the basis weight of the inorganic fiber mat.

[0025]

EXAMPLES Examples and comparative examples of the present invention will be shown below. Example 1 Glass fiber (thickness 9 μm, length 50 mm) and high density polyethylene fiber (thickness 6 denier, length 2 inch, melting point 1
(35 ° C) in a weight ratio of 2: 1 to a card machine, and defibrate and mix the fibers to discharge 8 g / m ² of cotton-like material into a band shape, fold it, and add 1 cm ^{2 to it.} Needle punching is performed at a density of 40 points per unit, and the basis weight is 500 g /
obtain a fiber mat of m ² (width 140cm).

The needle used for the needle punch is a needle having a blade portion shown in FIGS. 1A and 1B, the blade diameter is 0.6 mm, and the barb kick-up height (0.
01mm) and the throat depth (0.10mm) is 0.
11mm, barb spacing in the same row is 6.3mm.

10 cm × 10 in the width direction from the fiber mat
Take 10 sample pieces of cm and take 3 rows in the length direction,
Sample pieces of 30 points in total were taken, and the weight of each piece was measured, and the coefficient of variation (%) (standard deviation / average value × 10)
0) was measured. As a result, the coefficient of variation of the fiber mat weight was 4.3%.

Width 25 mm × 15 from the above fiber mat
A 0 mm sample piece was taken and its tensile strength was measured. As a result, the tensile strength of the fiber mat was 460 g / 25 mm width.

High-density polyethylene films (thickness: 100 μm, melting point: 135 ° C.) were laminated on the upper and lower sides of the fiber mat, and heated and pressed at a pressure of 4 kg / cm ² for 3 minutes with a pressing machine at 200 ° C. to form a high-density polyethylene film. Both the fiber and the film of Example 1 were melt-impregnated to produce a thermoformable fiber composite material.

This thermoformable fiber composite material was heated in an oven at 200 ° C. for 3 minutes, put in a press mold at room temperature, and heated and shaped at a pressure of 0.2 kg / cm ² for 30 seconds.
A molded body (core material for automobile ceiling material) having a thickness of 5 mm was obtained.

This molded body is cut to have a thickness of 5 mm and a width of 50.
A sample piece of mm × 150 mm in length was prepared, and the bending strength of this sample piece was measured according to JIS K7221. As a result, the bending strength of the molded product was 2.2 kg / 50 mm width.

Example 2 Instead of a fiber mat having a basis weight of 500 g / m ² , a basis weight of 4 was obtained.
The fiber mat was 50 g / m ² . Otherwise, Example 1
I went the same way.

As a result, the coefficient of variation of the weight of the fiber mat was 4.8% and the tensile strength of the fiber mat was 430 g / 25 mm.
The width and bending strength of the molded body were 2.0 kg / 50 mm width.

Comparative Example 1 A needle used for needle punching has a blade diameter of 0.8 mm,
The total of the barb kick-up height (0.07 mm) and throat depth (0.16 mm) was 0.23 mm, and the barb spacing in the same row was changed to 3.3 mm. Otherwise, Example 1
I went the same way.

As a result, the coefficient of variation of the weight of the fiber mat was 9.2% and the tensile strength of the fiber mat was 700 g / 25 mm.
The width and bending strength of the molded body were 1.7 kg / 50 mm width.

Comparative Example 2 Instead of a fiber mat having a basis weight of 500 g / m ² , a basis weight of 4
The fiber mat was 50 g / m ² . Otherwise, Comparative Example 1
I went the same way.

As a result, the coefficient of variation of the weight of the fiber mat was 9.7% and the tensile strength of the fiber mat was 680 g / 25 mm.
The width and bending strength of the molded body were 1.5 kg / 50 mm width.

[0038]

As described above, according to the method for producing a thermoformable fiber composite material of the present invention, the inorganic fiber mat is subjected to needle punching, and the inorganic fiber mat is melt-impregnated with the thermoplastic resin to form the thermoformable fiber composite material. When manufacturing the material, use a needle with a blade diameter of 0.4 to 0.65 mm, a total barb kick-up height and throat depth of 0.02 to 0.18 mm, and a barb spacing of 4 to 8 mm in the same row. Needle punching is applied to the inorganic fiber mat, which allows the inorganic fiber mat to be loosely entangled with each other and bulky,
Moreover, the variation in the weight per unit area is reduced.

As a result, the thermoformable fiber composite material obtained has a degree of freedom in the thickness direction, and when the thermoformable fiber composite material is heated and thermoformed, the inorganic material bound by the thermoplastic resin is used. Breakage of the fiber binding portion is prevented, and the bending strength of the obtained molded product is improved. Moreover, variations in mechanical strength of the thermoformable fiber composite material and its molded product are improved.

Therefore, the thermoformable fiber composite material obtained by the present invention is light in weight, mechanical strength, cushioning property,
It has good sound absorbing properties, heat resistance and heat shaping properties, and especially has improved bending strength, so that it can be suitably used, for example, as a core material for an automobile ceiling material.

[Brief description of drawings]

1 (a) is a perspective view showing an example of a blade portion of a needle used in the present invention, and FIG. 1 (b) is FIG.
It is an II sectional view of (a).

[Explanation of symbols]

 10 blade 11 barb 12 clamp D blade diameter H barb kick-up height S barb throat depth L barb spacing in the same row

Claims (1)

[Claims] 1. When producing a thermoformable fiber composite material by needle-punching an inorganic fiber mat and melt-impregnating the inorganic fiber mat with a thermoplastic resin, a blade diameter is 0.4 to 0.65 mm, and a barb is used. The thermoformability is characterized in that the inorganic fiber mat is needle-punched using needles having a total kick-up height and throat depth of 0.02 to 0.18 mm and barb intervals of 4 to 8 mm in the same row. Manufacturing method of fiber composite material.