JP2003183960A - Polyacrylonitrile based carbon fiber reinforced oxidized fiber sheet and method for producing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a lightweight polyacrylonitrile (PAN) oxidized fiber sheet without occupying much space, having high strength and good dimensional stability, scarcely extending, not causing delamination when used or processed and scarcely causing breakage or deformation during post-processing. <P>SOLUTION: This PAN based carbon-fiber reinforced oxidized fiber sheet 2 comprises a PAN based carbon opened fiber material 4 prepared by opening along the fiber axis, PAN oxidized fiber nonwoven fabrics or webs 6 and 8 laminated onto one or both surfaces of the opened fiber material 4 and interlaced fibers 10 of the carbon fibers or oxidized fibers obtained by interlacing of the opened fiber material 4 with the nonwoven fabrics or the webs 6 and 8 in the thickness direction. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high-strength polyacrylonitrile (PAN) -based oxidized fiber sheet. More specifically, the present invention takes advantage of the excellent heat resistance and chemical stability. The present invention relates to a PAN-based oxidized fiber sheet suitable as an intermediate raw material for a carbonized material, and a method for producing the same.

[0002]

2. Description of the Related Art PAN-based oxidized fibers are used for heat insulating materials, heat resistant materials, non-combustible sheets, etc. because they are excellent in heat resistance and chemical resistance stability. Furthermore, when using this as an intermediate raw material for carbon fiber production, the carbonization yield is high,
It is an industrially important material because it provides a high-strength carbonized material.

[0003] As one type of structure obtained by processing oxidized fibers into a sheet, there are conventional oxidized fiber nonwoven fabrics manufactured by the needle punch method and oxidized fiber nonwoven fabrics manufactured by the water jet method.

Oxidized fiber non-woven fabric having a low basis weight and a small thickness is space-saving and lightweight. However, this non-woven fabric having a low basis weight and a small thickness has low tensile strength and is easily stretched, so that when it is applied to the above-mentioned applications, it has poor dimensional stability and is likely to be cut or deformed during post-processing. It is possible to stack different types of sheets in order to improve the problem of the lack of strength and elongation of the oxidized fiber nonwoven fabric, but in this case, there is a problem in that the sheets are peeled from each other.

[0005]

DISCLOSURE OF THE INVENTION As a result of intensive studies on the above problems to be solved, the present inventor has found that a PAN-based oxidized fiber non-woven fabric or web and a PAN-based carbon fiber opened by extending the fiber axis along one direction. By superposing the fibers and entangled them in the thickness direction with a fiber entanglement device such as a needle punch method or a water jet method, these are integrated and the strength in the drive direction (length direction) of the fiber entanglement device is improved. It has been found that a PAN-based oxidized fiber sheet reinforced with carbon fibers having improved and suppressed elongation can be obtained.

[0006] Further, in this oxidized fiber sheet, it has been found that the opened body and the non-woven fabric are firmly integrated with each other, so that mutual layer peeling is prevented, and the present invention has been completed.

[0007] Therefore, an object of the present invention is to provide a PAN-based oxidized fiber sheet and a method for producing the same, which solve the above problems.

[0008]

The present invention which achieves the above-mentioned object is described below.

[1] A polyacrylonitrile-based carbon fiber spreader having a fiber axis opened in one direction, and a polyacrylonitrile-based oxidized fiber nonwoven fabric or web stacked on one side or both sides of the spreader, A polyacrylonitrile-based carbon fiber reinforced oxide fiber sheet comprising an open fiber and an entangled fiber of an oxidized fiber or a carbon fiber that entangles the nonwoven fabric or the fiber of the web in the thickness direction.

[2] The basis weight (W (g / m ² )) and the tensile strength (S (N / cm)) in the length direction of the polyacrylonitrile-based carbon fiber-reinforced oxidized fiber sheet are S / W = 1. 7 to 4.9 20 ≦ W ≦ 500 49 ≦ S ≦ 784 is satisfied, and the tensile elongation in the length direction is 2 to 15%.
The polyacrylonitrile-based carbon fiber reinforced oxidized fiber sheet according to [1].

[3] A polyacrylonitrile-based oxidized fiber nonwoven fabric or web is stacked on one side or both sides of a polyacrylonitrile-based carbon fiber opened body whose fiber axis is opened in one direction, and then the above-mentioned opened body is opened. A method for producing a polyacrylonitrile-based carbon fiber reinforced oxidized fiber sheet, characterized in that the fibers and the fibers of the non-woven fabric or the web are entangled in the thickness direction to be integrated.

[4] The method for producing a polyacrylonitrile-based carbon fiber reinforced oxide fiber sheet according to [3], wherein the polyacrylonitrile-based carbon fiber spread material has a basis weight of 5 to 35 g / m ² .

[5] The method for producing a polyacrylonitrile-based carbon fiber-reinforced oxidized fiber sheet according to [3], wherein the basis weight of the polyacrylonitrile-based oxidized fiber nonwoven fabric or web is 10 to 200 g / m ² .

[6] Basis weight of polyacrylonitrile-based carbon fiber-reinforced oxidized fiber sheet (W (g / m ² )) and basis weight of polyacrylonitrile-based carbon fiber opened body (W1 (g / m ² ))
m ² )) satisfies the following relationship: W1 / W = 0.05 to 0.20. The method for producing a polyacrylonitrile-based carbon fiber reinforced oxidized fiber sheet according to [3].

[0015]

DETAILED DESCRIPTION OF THE INVENTION The present invention will be described below with reference to the drawings.

FIG. 1 shows the polyacrylonitrile (P
It is a schematic sectional drawing which shows an example of an AN) type oxidation fiber sheet.

In the PAN-based oxidized fiber sheet 2 of the present invention, the PAN-based oxidized fiber nonwoven fabrics 6 and 8 are stacked on both surfaces of the PAN-based carbon fiber spreader 4 in which the fiber axis is opened in one direction. Become.

As for the fibers of the spread material 4 and the fibers of the nonwoven fabric or the webs 6 and 8, as shown in FIG. 1, entangled fibers 1 of carbon fibers or oxidized fibers entangled in the thickness direction of the sheet.
0 has been inserted, and the entangled fiber 10 is the opened fiber 4
And the non-woven fabric or webs 6 and 8 are completely penetrated or stabbed in the middle, that is, entangled by these operations, so that the spread body 4 and the non-woven fabrics or webs 6 and 8 are integrated.

The PAN-based oxide fibers constituting the above nonwoven fabric or webs 6 and 8 are, for example, 10 to 60 at an initial oxidation temperature of 220 to 250 ° C. in a PAN precursor in air.
After the partial oxidation treatment, it can be obtained by performing the oxidation treatment at a maximum temperature of 250 to 280 ° C. with a temperature gradient of 0.2 to 0.9 ° C./min, and any conventional PAN-based oxidized fiber can be used. Proper specific gravity of PAN-based oxidized fiber is 1.36 to 1.44, and proper fineness is 0.5 to 4.0 dt.
ex.

The PAN-based carbon fiber is, for example,
It can be obtained by heating the PAN-based oxidized fiber in an inert gas atmosphere and continuously carbonizing it.
Nitrogen, argon, helium or the like can be used as the inert gas. Carbonization temperature is 1300 to 2500 ° C
Is preferred.

The method for producing the PAN-based carbon fiber reinforced oxidized fiber sheet of the present invention will be described below with reference to FIG.

In FIG. 2, reference numeral 12 is a PAN before the opening treatment.
Carbon fiber tow, 14 is a PAN-based carbon fiber tow during fiber-spreading treatment, and 16 is a PAN-based carbon fiber spreader after fiber-spreading treatment, that is, before integration. The opening process itself is a technique known to those skilled in the art.

The PAN-based carbon fiber spreader 16 in which the fiber axis used in the PAN-based carbon fiber-reinforced oxidized fiber sheet of the present invention is opened along one direction preferably has a basis weight of 5 to 35 g / m ^2. .

When the basis weight of the spread fiber 16 is less than 5 g / m ² , the strength of the obtained PAN-based carbon fiber-reinforced oxidized fiber sheet is low and it tends to stretch. Therefore, the PAN obtained
The carbon fiber reinforced oxide fiber sheet is not preferable because it has poor dimensional stability and a processed product manufactured using the same tends to be cut or deformed during post-processing.

When the basis weight of the spread fiber 16 exceeds 35 g / m ² , the obtained PAN-based carbon fiber-reinforced oxidized fiber sheet is too large and heavy, which is not preferable because it is difficult to handle such as taking up space.

Then, as shown in FIG.
Then, the PAN-based oxidized fiber non-woven fabric or the webs 6 and 8 are stacked on both sides of the spread material 16). The PAN-based oxidized fiber nonwoven fabric or the webs 6 and 8 preferably have a basis weight of 10 to 200 g / m ² .

As the non-woven fabric or webs 6 and 8,
For example, a web obtained by carding a cotton obtained by cutting a PAN-based oxidized fiber to a fixed length may be used, or the web may be obtained by needle punching or continuously punching with a water jet in a water jet method. The non-woven fabric may be used.

Thereafter, the piled PAN-based carbon fiber spreader 4 and the PAN-based oxidized fiber nonwoven fabric or webs 6 and 8 are used.
Are punched by a conventional method to obtain the PAN-based carbon fiber-reinforced oxidized fiber sheet of the present invention.

The PAN of the present invention obtained as described above
The carbon fiber reinforced oxide fiber sheet has a basis weight (W (g /
m ² )) and the tensile strength (S (N / cm)) in the longitudinal direction satisfy the relationship of S / W = 1.7 to 4.9 25 ≦ W ≦ 500 49 ≦ S ≦ 784, and Tensile elongation in the length direction is 2 to 15%
Is preferred.

Further, the basis weight of the PAN-based oxidation fiber sheet of the present invention ^{(W (g / m 2)} ), PAN -based carbon fiber reinforced oxide fibers open繊体the basis weight ^{(W1 (g / m 2)} ) and is, It is preferable to satisfy the relationship of W1 / W = 0.05 to 0.20.

Adjustment to this range is performed by adjusting the PA before integration.
It can be performed by adjusting the basis weight of the N-based oxidized fiber nonwoven fabric or web or the basis weight of the PAN-based carbon fiber opened body, and / or by adjusting the needle punching condition and the water jet processing condition at the time of integration.

In the above manufacturing method, the PAN-based carbon fiber reinforced oxidized fiber sheet is formed by stacking PAN-based oxidized fiber nonwoven fabrics or webs on both sides of the PAN-based carbon fiber spreader, but not limited to this. The nonwoven fabric or the web may be stacked and produced only on one surface of the spread material.

[0033]

EXAMPLES The present invention will be described in detail with reference to the following examples and comparative examples.

Oxidized fiber sheets were produced under the conditions of the following examples and comparative examples. Various physical properties of the raw material oxidized fiber, carbon fiber opened body, oxidized fiber nonwoven fabric or web, and oxidized fiber sheet were measured by the following methods.

Specific gravity: Liquid replacement method (JIS R-7601,
Substitution liquid: ethyl alcohol).

Thickness: 200 g with a circular plate having a diameter of 30 mm
Was measured under a load (2.8 kPa).

Oxidized fiber sheet performance: Tensile strength and tensile elongation were measured according to JIS L-1096.

Basis weight: Calculated from the mass per unit area and the thickness measured under the above conditions.

Example 1 A cut fiber (51 mm) of PAN-based oxidized fiber (fineness: 2 dtex, specific gravity: 1.39) was carded to obtain a web having a basis weight of 30 g / m ² and a width of 1.0 m. Also, P
An carbon fiber tow (fineness 1 dtex, number of filaments 90,000, filament tensile strength 4.0 GPa) is opened along one direction of the fiber axis, and carbon fiber having a basis weight of 6 g / m ² and a width of 1.0 m An open fiber was obtained. After superposing this open body and the above-mentioned web, the punching treatment is continuously performed by the needle punching method (punching number: 150 times / in.
² (150 times / (2.54 cm) ² ), completely penetrate the fiber in the thickness direction or pierce it halfway, that is, the fibers are entangled by these operations, and the opened fiber and the web are integrated. The obtained PAN-based carbon fiber-reinforced oxidized fiber sheet was obtained.

The obtained oxidized fiber sheet has a basis weight of 36 g.
/ M ² , thickness 0.4 mm, longitudinal tensile strength 1
18N / cm, the tensile elongation in the length direction is 3.5%, the ratio of the tensile strength in the length direction to the basis weight (S / W) is 3.3, and the basis weight and carbon of the carbon fiber spreader are The ratio (W1 / W) to the basis weight of the fiber-reinforced oxidized fiber sheet is 0.17,
The sheet had good physical properties.

Comparative Example 1 A cut fiber (51 mm) of PAN-based oxidized fiber (fineness: 2 dtex, specific gravity: 1.39) was carded to obtain a web having a basis weight of 40 g / m ² and a width of 1.0 m. This non-woven fabric is continuously punched by the needle punching method (punching number 150 times / in ² (150 times / (2.54
cm) ² )), and the fiber was completely penetrated in the thickness direction or was inserted halfway, that is, a PAN-based oxidized fiber sheet in which the fibers were entangled by these operations was obtained.

The oxidized fiber sheet thus obtained has a basis weight of 40 g.
/ M ² , thickness 0.5 mm, longitudinal tensile strength 7.8 N / cm, longitudinal tensile elongation 37%, longitudinal tensile strength to basis weight ratio (S / W ) Was 0.20, which was not a sheet having good physical properties.

Example 2 A cut fiber (51 mm) of PAN-based oxidized fiber (fineness: 2 dtex, specific gravity: 1.39) was carded to obtain a web having a basis weight of 30 g / m ² and a width of 1.0 m. Also, P
An AN-based oxidized fiber tow (fineness: 2 dtex, number of filaments: 90,000) was subjected to opening treatment along a fiber axis in one direction to obtain an oxidized fiber opened body having a basis weight of 20 g / m ² and a width of 1.0 m. After superposing the above webs on the upper and lower layers of this spreader, the punching treatment was continuously performed by the needle punching method (punching number 150 times / in ² (150 times / (2.54
cm) ² )) and completely penetrate the fiber in the thickness direction or pierce it halfway, that is, the fibers are entangled by these operations,
A PAN-based carbon fiber-reinforced oxidized fiber sheet in which the spread body and the web were integrated was obtained.

The oxidized fiber sheet obtained had a basis weight of 80 g.
/ M ² , thickness 0.5 mm, longitudinal tensile strength 4
4 N / cm, tensile elongation in the lengthwise direction is 32%, ratio of tensile strength in the lengthwise direction to basis weight (S / W) is 0.55, basis weight of carbon fiber opened body and carbon fiber reinforced oxidized fiber sheet The ratio (W1 / W) to the fabric weight was 0.25, which was not as good as the sheet of Example 1, but was a sheet having good physical properties.

[0045]

INDUSTRIAL APPLICABILITY The PAN-based carbon fiber reinforced oxidized fiber sheet of the present invention has high tensile strength because it is reinforced by the PAN-based carbon fiber spreader having the fiber axis opened in one direction. Furthermore, when using or processing, it does not take up space,
A sheet that is lightweight, has high strength, is difficult to stretch, does not peel off layers, has good dimensional stability, and is unlikely to be cut or deformed during post-processing.

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional view showing an example of a PAN-based carbon fiber-reinforced oxidized fiber sheet of the present invention.

FIG. 2 is a schematic cross-sectional view showing a PAN-based carbon fiber tow and a spreader used for the PAN-based carbon fiber-reinforced oxidized fiber sheet of the present invention, showing before the opening, during the opening, and after the opening. It is a figure.

[Fig. 3] P at the time of stacking an opened body and a nonwoven fabric or a web
It is a schematic sectional drawing which shows an example of an AN carbon fiber reinforced oxidation fiber sheet.

[Explanation of symbols]

2 PAN-based oxidized fiber sheet 4 PAN-based carbon fiber spreader 6, 8 PAN-based oxidized fiber nonwoven fabric or web 10 Entangled fiber of carbon fiber or oxidized fiber entangled in the thickness direction 12 PAN-based carbon fiber tow before opening treatment 14 PAN-based carbon fiber tow during opening processing 16 PAN-based carbon fiber opened body after opening processing

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Yusuke Takami             Toho Tena 234 Uechikari, Nagaizumi-cho, Sunto-gun, Shizuoka Prefecture             X Co., Ltd. F-term (reference) 4L047 AA03 AA17 AA28 BA03 CA02                       CA03 CA05 CA19 CB01

Claims (6)

[Claims] 1. A polyacrylonitrile-based carbon fiber spreader having a fiber axis opened in one direction, a polyacrylonitrile-based oxidized fiber nonwoven fabric or a web stacked on one side or both sides of the opened body, and the opening. A polyacrylonitrile-based carbon fiber reinforced oxide fiber sheet comprising carbon fibers or entangled fibers of oxide fibers that entangle the fibers of the fibrous body with the fibers of the non-woven fabric or the web in the thickness direction. 2. The weight per unit area (W (g / m ² )) and the tensile strength (S (N / cm)) of the polyacrylonitrile-based carbon fiber-reinforced oxidized fiber sheet are S / W = 1. 7-4.9 20 ≦ W ≦ 500 49 ≦ S ≦ 784 is satisfied, and the tensile elongation in the length direction is 2 to 15%.
The polyacrylonitrile-based carbon fiber reinforced oxidized fiber sheet according to claim 1. 3. A polyacrylonitrile-based carbon fiber spreader having a fiber axis opened in one direction is laminated on one or both sides thereof with a polyacrylonitrile-based oxidized fiber nonwoven fabric or web, and then the fibers of the spreader. A method for producing a polyacrylonitrile-based carbon fiber reinforced oxide fiber sheet, characterized in that the non-woven fabric or web fibers are entangled in the thickness direction to be integrated. 4. The method for producing a polyacrylonitrile-based carbon fiber reinforced oxidized fiber sheet according to claim 3, wherein the basis weight of the polyacrylonitrile-based carbon fiber opened body is 5 to 35 g / m ² . 5. The method for producing a polyacrylonitrile carbon fiber reinforced oxide fiber sheet according to claim 3, wherein the basis weight of the polyacrylonitrile oxide fiber nonwoven fabric or web is 10 to 200 g / m ² . 6. A basis weight of a polyacrylonitrile-based carbon fiber reinforced oxide fiber sheet (W (g / m ² )) and a basis weight of a polyacrylonitrile-based carbon fiber opened body (W1 (g / m ² )).
m ² )) satisfies the following relationship: W1 / W = 0.05 to 0.20. 4. The method for producing a polyacrylonitrile-based carbon fiber reinforced oxidized fiber sheet according to claim 3.