JPH0533249A - High-density felt of carbon fiber and production thereof - Google Patents

Abstract

PURPOSE:To obtain the title felt suitable as a thermal insulating material for high-temperature heat treatment by laminating one or both of the surfaces of a fibrous butt layer put to flame-proofing, infusibilizing or carbonizing treatment with (non)woven fabric(s) carbonizable, graphitizable by baking followed by unification through needle punching and then baking. CONSTITUTION:One or both of the surfaces of a butt layer of fibers put to flame-proofing, infusibilizing or carbonizing treatment is laminated with woven, knit or nonwoven fabric(s) of polymeric fibers carbonizable or graphitizable by baking followed by needle punching on the laminated surface side to effect unification, and the resulting monolithic form is baked, thus obtaining the objective felt.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a carbon fiber high density felt suitable as a heat insulating material, a cushioning material, a material for secondary battery electrodes and the like during high temperature heat treatment, and a method for producing the same.

[0002]

2. Description of the Related Art Felts made of carbon fiber are excellent in heat resistance and heat insulation at high temperatures.
It is used as a heat insulating material in high temperature furnaces such as vacuum deposition furnaces and semiconductor single crystal growth furnaces.

This kind of carbon fiber felt is required to have heat insulating properties, mechanical strength and durability in order to raise and lower the temperature in a short time, reduce power consumption, and downsize equipment. Since these three requirements are achieved by increasing the density of the felt, various contrivances have been made to develop a carbon fiber felt aiming at high density.

First, the first felt has a batt layer made of flame-proofed or carbonized fibers placed on the upper surface of a base cloth made of a woven or non-woven polymer fiber which is carbonized or graphitized by firing. The base cloth and the batt layer were integrated by needle punching from the side of the batt layer, and were obtained by firing this (JP-A-2-46891).

In the second felt, a base cloth made of carbon fiber woven cloth is brought into contact with one or both sides of the carbon fiber bat layer, and a part of the bat layer fibers is made by needle punching. The bat layer and the base fabric are integrated by entanglement of the fibers, and the integrated product is impregnated with a resin in order to prevent deformation and pulverization (JP-A-1-272854). Issue).

Further, the third felt is made by mixing carbon fibers with polymer fibers which are carbonized or graphitized by firing,
It is obtained by mechanically compressing and entwining the fibers and the polymer fibers, and then firing them (Japanese Patent Laid-Open No. 14665/1993).

[0007]

However, these conventional felts have various drawbacks and are not completely satisfactory. That is, the first felt had an average bulk density of at most 0.05 g / cm ³ after firing, and was inferior in heat insulation, mechanical strength, and durability.

The second felt has a batt layer and a base cloth made of carbon fiber, and it is not only expensive to weave with a yarn of carbon fiber, but the elongation of the carbon fiber is remarkably small, and needle punching is performed. In this case, the fiber is frequently broken, and the product is easily deformed or powdered.Therefore, a resin impregnation process is required to prevent this, and the number of work processes is increased. There was also a problem that the property deteriorates.

Further, the effect of tightening by needle punching is generally remarkably improved by entanglement with a woven cloth having a high fiber density, but the third felt uses a blended spun bat without using a woven cloth or the like. It is difficult to tighten because it is a thing, and it is inevitable to increase the number of times of needle punching to obtain a desired tightening. Therefore, it seems that the carbon fiber in the mixed spinning bat is cut, and the strength as a felt becomes small, and the production itself becomes difficult especially for a thin material (2 to 3 mm). The high number of needle punching means that the work time is long. It should be noted that the whole vat should be mixed uniformly and
^It is undeniable that the density of non-carbon fibers, which occupy about _1/2 amount, decreases due to weight loss due to carbonization.

The present invention has been made in view of the above circumstances, and an object thereof is a felt of 1.5 to 15 mm having an average bulk density of 0.1 g / cm ³ or more, particularly a thin material (2
It is to provide a carbon fiber high-density felt capable of obtaining a carbon fiber felt having a size of up to 5 mm) with good workability and a method for producing the same.

[0011]

In order to achieve the above-mentioned object, the carbon fiber high-density felt according to the first aspect of the present invention comprises a bat layer composed of flame-resistant, infusibilized or carbonized fibers, and a bat layer A woven fabric, a knitted fabric or a non-woven fabric made of a polymer fiber carbonized or graphitized by firing, which is placed on at least one side and integrated with the bat layer by needle punching from the side of the placement side, and fired It is characterized by being carbonized or graphitized by.

The method for producing a carbon fiber high-density felt according to the second aspect of the present invention is a polymer system in which at least one surface of a batt layer made of flame-proofed, infusibilized or carbonized fiber is carbonized or graphitized by firing. A woven fabric, a knitted fabric, or a non-woven fabric of fibers is placed, these are integrated by needle punching from the placement surface side, and this is fired.

High density means an average bulk density of 0.1 g / cm.
Says ³ or more. Further, the carbonized or graphitized polymer fiber means cellulosic fiber such as rayon, cotton, hemp, etc., polyacrylonitrile fiber, or phenol resin fiber.

[0014]

In the first aspect of the invention, since it has the above-mentioned constitution, a woven fabric, a knitted fabric or a non-woven fabric after firing (hereinafter referred to as "woven fabric or the like") and a woven fabric entangled with the batt layer fibers. The fibers are highly carbonized or graphitized to become substantially the same quality as the batt layer fibers, and there is no problem when used in a high temperature furnace or the like.

According to the first aspect of the invention, the carbonized or graphitized fiber such as woven fabric is sufficiently entangled with the fiber in the batt layer, so that the thickness does not recover after firing.
It can be maintained at a high density of 1 g / cm ³ or more. Note that the woven fabric and the like in the present invention are also carbonized or graphitized by firing to reduce the weight, but since a considerable amount of fibers such as the woven fabric remains disposed on the surface of the felt even after needle punching, the whole felt, particularly The feature is that the influence on the internal density decrease and the morphological instability is kept small.

A second aspect of the present invention is a method for producing a carbon fiber high-density felt by integrating a woven cloth or the like and a batt layer by needle punching from the side of the woven cloth or the like as described above.

According to this method, at the time of needle punching, when fibers such as a woven fabric are hung on the needle prick and pushed downward to penetrate the batt layer, the constituent fibers of the nearby batt layer are also dragged downward. Be pushed away. When pushing down the constituent fibers of the bat layer, since the needle spines are already covered with fibers such as a woven fabric, the spines do not catch the constituent fibers of the bat layer so much, and the constituent fibers of the bat layer It is possible to suppress damage and disconnection of the material.

As described above, according to the second aspect of the present invention, the needle punching from the side of the woven cloth or the like causes the density of the woven cloth and the fibers of the normal woven cloth before carbonization or graphitization to increase with the entanglement. The rise and the suppression of fiber breakage of the batt layer are combined with each other, so that the batt layer made of carbon fiber having an extremely small elongation can have a high density.

Further, according to the second aspect of the invention, even in the firing step, fibers such as a woven fabric penetrate the batt layer and are entangled with the batt fibers, and the batt constituent fibers in the vicinity thereof are also dragged to entangle the batt fibers with each other. The carbon fiber high-density felt can be obtained without increasing the thickness and recovering the thickness or deforming because the fibers are entangled with each other.

[0020]

EXAMPLES The present invention will be specifically described below based on illustrated examples and experimental examples. FIG. 1 shows a production example for obtaining a flat carbon fiber high-density felt.

In FIG. 1, a woven cloth 2 of polymeric fibers that are carbonized or graphitized by firing is placed on the upper surface of a batt layer 1 made of flame-proofed, infusibilized or carbonized fibers, and ordinary needles are placed. The machine 10 is needle punched. The needle punching at this time is performed from the side of the woven cloth 2 or the like, whereby the bat layer 1 and the woven cloth 2 are integrated, and the fibers of the woven cloth 2 are entangled with the fibers of the bat layer 1 and the bat layer 1 is entangled. Layer 1 is dense.

Next, this material is fired and the fibers 2a of the woven cloth 2 which are entangled with the fibers of the woven cloth 2 and the bat layer 1 are carbonized or graphitized to have substantially the same quality as the fibers of the bat layer 1. As a result, the carbon fiber high-density felt 3 shown in FIG. 2 can be obtained.

In FIG. 1, 11 is a needle, 12 is a stripper, and 13 is a bed.

At this time, the bat layer 1 has a thickness of 5 to 6
0 mm is suitable. If it is thinner than 5 mm, it is difficult to obtain a uniform one by needle punching, and if it is thicker than 60 mm, the effect of tightening the woven cloth 2 during needle punching becomes small. The woven cloth 2 is made of cotton, rayon, hemp, polyacrylonitrile fiber, or phenol resin fiber, etc., and all the fibers which are substantially the same quality as the constituent fibers of the batt layer 1 by carbonization or graphitization. Woven cloth,
Knitted fabric, non-woven fabric, or web-like material can be used. The woven fabric has a warp and weft density of 12 to 70 yarns / cm, and a spun bond can be used as the non-woven fabric. Further, the web-like material is as-carded, and further pressed. It is also possible to use a higher density.

When the basis weight of the woven fabric or the like is 20 g / m ² or less in the case of the woven fabric, the yarn density becomes too small, or the yarn becomes too thin, and the needle does not catch the fibers of the woven fabric during needle punching. If it is 250 g / m ² or more, it may enter the batt layer 1 and damage the batt fibers. On the other hand, when the needle punching is performed, the fibers of the woven cloth caught on the needle prick are obstructed by the excess fibers around the needle and the needle is smooth. It becomes difficult for the bat layer 1 to enter the inside.

The basis weight of the woven fabric 2 is 25 in the case of the woven fabric.
At 0 g / m ² or less, there is a sufficient tightening effect on the bat layer 1,
If it is more than this, it is rather uneconomical.
50 g / m ² is suitable.

In the case of a nonwoven fabric or a web-like material, the lower limit of the basis weight of the woven fabric or the like 2 is somewhat relaxed as compared with the above-mentioned woven fabric, but it is almost the same.

Furthermore, the number of times of needle punching at this time is minimum and sufficient, and is the best. The relationship between the number of punches when the woven cloth 2 is placed on the bat layer 1 and needle punching is performed from the woven cloth 2 side, and the strength and thickness of (bat layer 1 + woven cloth 2) are tested under the following conditions. A result of 1 was obtained.

Conditions: (1) Needle punching condition Needle: No. 32, number of pricks 3/3 rows (9 in total) Number of stitches: 40 / cm ² Needle depth: 20 mm Note * 1: Coal pitch that has been infusibilized and then carbonized. The thickness is 13 μm and the fiber length is 30 to 90 mm. * 2: 25 warps / cm, 23 wefts / cm

Results:

[Table 1]

As is apparent from Table 1, when the needle punching is increased once, the strength is about _^1/10, will become even more once increases the strength of about _^1/70, the cutting of fibers by needle punching It can be understood that the progress is remarkable.

The thickness (corresponding to the bulk density) of the (bat layer + cotton woven fabric) completely reached the target value (3.1 mm) only by the first needle punching, and the subsequent needle punching. No reduction in thickness has occurred. That is,
The desired bulk density can be obtained with one needle punching, and the bulk density cannot be increased even if the number of times is further increased.

It is speculated that the reason why the thickness does not decrease even if the number of times of punching is increased in this way is that the cutting of the fibers progresses and the shape cannot be maintained due to the entanglement of the fibers.

Therefore, since one needle punching is sufficient and the best, the working time is short and the working efficiency is improved.

As described above, the present invention is not limited to the flat felt in which the woven cloth or the like is integrated on the upper surface of the bat layer, and the following modified examples are also possible.

Even if the present invention is a flat sheet-like felt, a woven cloth or the like is brought into contact with both side surfaces of the bat layer, (bat layer + woven cloth, etc.) are successively laminated, or bat layers are woven together. It also includes a thick plate-like felt which is integrated by needle punching under further weak conditions by superposing the above.

The present invention also includes a cylindrical felt. In the case of the cylindrical shape, the batt layer and the woven cloth or the like are overlapped with each other, and needle punching is performed from the side of the woven cloth or the like while transferring the bat layer to the cylindrical needle bed. In this case, it is also possible to form a cylinder having a spiral multi-layer structure while adjusting the depth of the needle.

Experimental examples are shown below. Experimental Example 1 (A cotton woven cloth is used on one side of the batt layer) Condition: Effect of punching frequency described above Same as the condition for determining needle punching in the experiment Result: thickness of 3.05 mm and density of 0. felt arranged cotton fabric on one side of 158 g / cm ³ of the batt layer is obtained, after firing, to obtain a thickness 2.88 mm, a density of 0.108 g / cm ³ of carbon fiber-made high-density felts. This product was stable in shape and easy to handle without losing its shape.

Experimental Example 2 (using a knitted fabric of cotton yarn on both sides of the batt layer) Conditions: (1) Needle punching conditions Same as Experimental Example 1 Note * 1: Coal pitch that has been infusibilized and then carbonized. The thickness is 13 μm and the fiber length is 30 to 90 mm.

Under the above conditions, the knitted fabric was overlaid on the batt layer and needle punched once from the knitted fabric side with a needle depth of 17 mm. Then, this was turned upside down, and the same knitted fabric was overlaid on the batt layer side to obtain the needle depth. Needle punching was performed once at 12 mm.

Result: thickness 3.12 mm, density 0.162 g
/ Felt arranged knitted fabric on both sides of cm ³ of the batt layer is obtained, after firing, a thickness of 3.04 mm, density 0.112 g / cm ³
A high density felt made of carbon fiber was obtained. This product was morphologically stable and easy to handle.

Experimental Example 3 (1) Needle punching condition Needle: No. 36, number of stabs / 3 rows (9 in total) Number of stitches: 36 / cm ² (2) Fiber bat layer: carbon of Experimental Example 2 Fiber (three webs of 120 g / m ² are laminated to make 360 g / m ² ) Woven fabric, etc .: Rayon non-woven fabric (112 g / m ² ).

Under the above conditions, a batt layer was formed on the rayon nonwoven fabric, a rayon nonwoven fabric was further stacked on the batt layer, and needle punching was performed once at a needle depth of 15 mm from the side of the rayon nonwoven fabric that was finally placed. , Needle depth 11mm from the side of the first rayon non-woven fabric that has been turned upside down
Needle punched once.

Results: thickness 3.29 mm, density 0.147 g
A felt having rayon non-woven fabric on both sides of a batt layer of 1 / cm ³ was obtained, and after firing, had a thickness of 3.11 mm and a density of 0.11.
A carbon fiber high density felt of 7 g / cm ³ was obtained. This product was morphologically stable and easy to handle.

Experimental Example 4 (Cylindrical Felt) (1) Needle Punching Condition Needle: 36th, Number of Stabs / 3 Rows (9 in total) Number of Needles: 20 / cm ² Note * 1: 36 warps / cm, 28 wefts / cm

Under the above-mentioned conditions, the bat layer on the lattice carried by the rotating lattice and the one with the cotton woven fabric superposed thereon are spirally transferred onto a cylindrical needle bed, and the needle depth is 18 mm. Punching was done.
At this time, the needle punching was continuously performed until exactly two revolutions were made on the cylindrical needle bed. The obtained cylindrical felt is a batt layer, cotton woven cloth,
It was composed of a bat layer and a cotton woven fabric.

Result: thickness 3.85 mm, density 0.152 g
/ Cm ³ of a cylindrical felt was obtained, which had a thickness of 3.4 after firing.
A carbon fiber high density felt having a diameter of 8 mm and a density of 0.114 g / cm ³ was obtained. This product was particularly cylindrical and had a stable shape and was easy to handle.

[0048]

EFFECTS OF THE INVENTION Since the carbon fiber high-density felt according to the present invention has an average bulk density of 0.1 g / cm ³ or more, it has sufficient heat insulating properties, mechanical strength, and durability (not to lose its shape). is doing.

In the method for producing a carbon fiber high-density felt according to the present invention, a high-density felt having an average bulk density of 0.1 g / cm ³ or more is used for a short working time by using carbon fibers having an extremely small elongation. (Minimal number of needle punching) enables efficient manufacturing.

[Brief description of drawings]

FIG. 1 is a schematic view illustrating a method for producing a carbon fiber high-density felt according to the present invention.

FIG. 2 is a cross-sectional view of a carbon fiber high-density felt of the present invention.

[Explanation of symbols]

1 bat layer 2 woven cloth 3 Carbon fiber high-density felt 10 needle machine 11 needles 12 strippers 13 beds

Claims (2)

[Claims] 1. A batt layer made of flameproofed, infusibilized or carbonized fibers, and a batt layer placed on at least one side of the batt layer and integrated with the batt layer by needle punching from the side of the placing surface. A high density felt made of carbon fiber, which is composed of a woven fabric, a knitted fabric or a non-woven fabric made of a polymer fiber which is carbonized or graphitized by firing, and which is carbonized or graphitized by firing. 2. A woven fabric, a knitted fabric or a non-woven fabric of polymer fibers which are carbonized or graphitized by firing is placed on at least one surface of a batt layer made of flame-proofed, infusibilized or carbonized fibers, and A method for producing a high density felt made of carbon fiber, characterized in that the above is integrated by needle punching from the mounting surface side, and this is fired.