JPH0457949A - Production of blended felt consisting essentially of pitch-based carbon fiber - Google Patents

Abstract

PURPOSE:To stably and efficiently obtain the subject product having a uniform density and thickness in good yield without breaking a fiber assembly by blending fiber composed of a carbon precursor other than a pitch-based carbonaceous material in the fiber assembly of the pitch-based carbonaceous material in a specific proportion. CONSTITUTION:Fiber (preferably phenolic flameproofed yarn or polyacrylonitrile- based flameproofed yarn) composed of a carbon precursor is initially blended in a fiber assembly composed of a pitch-based carbonaceous material at (9:1) to (6:4) weight ratio to reduce frictional resistance between pitch-based carbon fibers. The aforementioned resultant mixed web is laminated and then subjected to treatment for bonding by physical or mechanical action such as needle punching to afford the objective product. Furthermore, the carbon precursor fiber other than the pitch-based carbonaceous material has preferably 50-150mm fiber length and 5-10% breaking elongation.

Description

[Detailed description of the invention] <Industrial application field> The present invention uses a fiber cane aggregate made of pitch-based carbon material as a raw material to produce heat insulating materials and C/C materials (carbon fiber reinforced carbon composite materials).
- It relates to a method for stably producing felt whose main component is pitch-based carbon fiber, which is a raw material for activated carbon fiber and the like.

<Prior art> In general, a method for producing felt mainly composed of carbon fibers is to melt-spun fiber-forming pitch to form a nonwoven fabric made of pitch fibers, as shown in Japanese Patent Publication No. 51-33223. After that, it is infusible and carbonized to obtain a carbon fiber (hereinafter abbreviated as CF) non-woven fabric, and then the obtained CF non-woven fabric is laminated and the weight per unit area is adjusted, and then needles are formed. A method to obtain felt by punching and a general method in which CF is applied to a card machine and then made into felt by a nildol punch, that is,
Fiber-forming pitch is melt-spun, infusible and carbonized to produce a CF aggregate, which is loosened into single fibers using a card machine (hereinafter abbreviated as fiber opening) and laminated in any amount to produce a CF aggregate per unit area. There is a method of obtaining felt by needle punching after adjusting the basis weight.

In the former method, a CF nonwoven fabric is made to exhibit the mechanical properties of CF, and then felt is formed by needle punching, so the single fibers forming the nonwoven fabric are pulled in three-dimensional directions with few degrees of freedom. Therefore, the highly rigid fibers are inevitably broken, and the produced felt inevitably has extremely weak shape retention.

On the other hand, in the latter method, a felt manufacturing method that uses fired CF as a starting material, the important point is the process of opening tow or sheet-like fibers made of aggregates of short fibers into single filaments. During the opening and manufacturing process using a carding machine, some of the fibers are powdered and some of them become extremely short fibers that fall during processing, and the fibers obtained as a carded web are at most 50-60%, which is poor yield. There are cases where it is impossible to proceed to the next step because the shape retention is extremely weak. Therefore, stable production of felt cannot be expected.

FIG. 1 shows a known carding machine, in which raw material CF is charged onto the surface of a cylinder 6 via a conveyor 1 via a feed roller 2 and a take-in roller 3, and a metal link embedded in the surface of the cylinder 6. The wire 7 moves the cylinder 6 in the direction of rotation. At the same time, the stripper 5 is installed and rotates so as to be almost in contact with the cylinder surface.
The needles on the surface of a plurality of roller cards 4 equipped with a roller card 4 are sequentially inserted into the raw material fibers, and the raw fibers are combed by the difference between the peripheral speed of the cylinder and the peripheral speed of the roller card.

Due to the large amount of intertwining of these IICFs, when a roller card needle is inserted into the raw material CF, which has a large movement resistance and is extremely brittle against bending, most of the caught fibers do not move and break on the spot. Therefore, in the next process, the docker 8, the web is stripped off by the vibrating comb 9 and passed through the calendar roller 10, resulting in a low product yield, and the web breaks under its own weight. The more the shape is retained, the more unstable it becomes.

<Problems to be Solved by the Invention> Therefore, the purpose of the present invention is to provide a method for making felt through a process of opening fibers made of a pitch-based carbon material that has high rigidity and bends against bending and has poor mutual entanglement. An object of the present invention is to provide a method for stably and efficiently producing felt containing pitch-based CF as a main component with a high yield and uniform density and thickness without causing breakage of the fibrous aggregate.

<! ! Means for Solving the Problem> The present invention provides a pitch-based carbon material by mixing fibers made of a carbon precursor other than pitch-based material into a fiber aggregate made of a pitch-based carbon material at a weight ratio of 9:1 to 6:4. A blended felt mainly composed of pitch-based carbon fibers, which is characterized in that the frictional resistance between carbon fibers is reduced, and then, after the mixed webs are laminated, they are bonded by physical or mechanical action. In this manufacturing method, it is preferable to use phenolic flame-resistant yarn or polyacrylonitrile flame-resistant yarn as the fiber made of a carbon precursor other than pitch-based yarn, and if necessary, the blended felt may be further carbonized. It can also be applied.

<Function> In producing carbon fiber felt suitable as a raw material for heat insulating materials, C/C materials, filter media, etc., the present invention provides infusible and
Carbon precursor fibers other than pitch-based fibers are mixed in a fibrous aggregate made of pitch-based carbon materials in various forms obtained after preliminary carbonization at a weight ratio of 9:1 to 6:4, and subjected to fiber opening treatment. After that, a mixed web is obtained, and then this mixed web is laminated to obtain the required basis weight, and then bonded by physical or mechanical action such as needle punching to obtain a felt, or the felt is further carbonized. This is a method for producing a blended felt whose main component is pitch-based carbon fiber.

Examples of the pitch-based carbon material include pitch-based carbon fibers, which are carbonized at 700° C. or higher.

Examples of carbon precursor fibers other than pitch-based fibers include hardened phenolic flame-resistant fibers, acrylic flame-resistant fibers, etc.
Carbonizable fibers may be mentioned. The carbon precursor fibers to be mixed have a weight ratio of the fibrous aggregate made of pitch-based carbon material to the carbon precursor fibers in the range of 9/1 to 6/4, preferably in the range of 872 to 6/4. mix it up like this.

In addition, it is preferable that the diameter of the carbon precursor fibers is approximately the same as that of the fibrous aggregate made of pitch-based carbon material, and the fiber length is also the same or less because mixing becomes easier. Therefore, the number of carbon precursor fibers to be mixed is 30 to 200 (2) Preferably, it is necessary to set it to 50-150-. Further, it is preferable to use a breaking elongation of 5% or more, preferably 10% or more, so that it does not easily break when bent.

In addition, in the present invention, the fibrous aggregate made of pitch-based carbon material and the carbon precursor fiber are mixed while being opened by a generally well-known air blow, and are mixed using a card machine as shown in Fig. 2. Following the auto feeder 11, which is a raw material supply device, a carding machine performs a strip-forming process to obtain a carded web. Since the fibers of this carded web are aligned in the direction of travel, it is possible to cross-laminate them using a ramping device 12, adjust the basis weight and thickness, and then pass them through a needle punching device 13 to obtain felt. The felt obtained in this step A can be supplied in this state as a raw material felt for heat insulating materials or activated carbon fibers.Furthermore, by performing a carbonization treatment to match the characteristics of the carbon precursor fiber, it can be used as a raw material for pitch-based CF. It is also possible to obtain a felt composed of 100% CF as a component.

Incidentally, instead of the needle punch operation, a stitch bond method can also be used.

The key point of the present invention is to mix fibers made of a carbon precursor other than pitch-based into a fibrous aggregate made of pitch-based carbon material after carbonization or pre-carbonization to weaken the resistance to movement of single fibers. The purpose is to prevent fiber breakage during the stripping process (during card processing), but this is due to the pitch type C
The point is that the frictional resistance between F and other carbon precursor fibers is lower than that between pitch CF.

By mixing a predetermined amount of the carbon precursor fibers into a fibrous aggregate made of pitch-based carbon material, it is possible to suppress shortening of fibers not only in the fabrication process but also in the needle punching process, resulting in a felt that is homogeneous and has excellent strength. It can be manufactured.

Now, if the mixed web contains carbon precursor fibers in a 6:4 ratio, or 40% by weight, it not only increases the production cost but also reduces the carbonization of the felt made from this camphor raw material. In this case, shrinkage of the carbon precursor fibers causes unevenness in the thickness, basis weight, etc. of the felt, and the yield of the desired felt decreases.

On the other hand, when the amount of carbon precursor fibers mixed is in the range of 9:1, that is, 10
In the case of no droplets by weight, a stable carded web cannot be obtained in the strip-forming process, making it impossible to achieve the object of the present invention. Therefore, in the present invention, the amount of carbon precursor fibers mixed is limited to a range in which the weight ratio of the fiber aggregate made of pitch-based carbon material to the carbon precursor fibers is in the range of 9:1 to 6:4.

The present invention will be explained in more detail below using Examples and Comparative Examples.

<Example> Example 1 Pitch-based CF obtained by centrifugally spinning fiber-forming pitch, making it infusible and carbonizing it (average diameter 18μ, average tensile strength 60k)
g/m', average tensile modulus 3 ton/sw"
) was pre-opened to obtain a single yarn mass with an average fiber length of 60 threads.

Kynor fiber (trade name of phenolic fiber sold by Japan Kynor Co., Ltd., average diameter 14 μ, average tensile strength 20 kg/am”, elongation approximately 30%, average fiber length 51 kaku)
were mixed by air blowing in a ratio of 85:15 by weight, and a web was produced using a carding machine shown in FIG. 2, followed by lamination and needle punching to obtain felt.

Web yield was approximately 80%. In addition, the basis weight is approximately 5
The thickness and density were uniform at 00 g/rd.

Example 2 Pitch-based CF obtained by centrifugally spinning fiber-forming pitch, infusible and carbonized (average diameter 18μ, average tensile strength 60k)
g/m'', average tensile modulus of elasticity 3 ton/m'') was pre-opened to obtain a single yarn mass with an average fiber length of 60 ton/m.

To this, Kynol fiber (trade name of phenolic fiber sold by Nippon Kynol Co., Ltd., average diameter 14 μ, average tensile strength 20 kg/-2, elongation approximately 30%, average fiber length 51 m) was added in a ratio of 85:15 by weight. The materials were mixed by an air blow method, processed using a card machine shown in FIG. 2, laminated and needle punched, and then carbonized at a maximum temperature of 900° C. to obtain felt. Web yield was approximately 80%. In addition, this felt has a basis weight of approximately 500g/lrr and a thickness of
The density co-average was -.

Example 3 Next, the same pitch-based CF as in Example 1 and the aforementioned Kynol fiber were mixed in a ratio of 60:40 and treated in the same manner as in Example 2 to obtain felt, but this felt also had different thicknesses and
The density co-average was -. The web yield was 85%.

Example 4 Pitch-based CF obtained by centrifugally spinning fiber-forming pitch, infusible and carbonized (average diameter 18μ, average tensile strength 60k)
g/w", average tensile elastic modulus 3 ton 7wm") was opened in advance to obtain a single yarn mass with an average fiber length of 60+*.

This is combined with acrylic flame-resistant Pyromex (trade name of flame-resistant yarn made from acrylic fiber sold by Toho Rayon Co., Ltd.).
The average diameter is 14 μ, the average tensile strength is 17 kg/s*, and the elongation is 2.
0%, average fiber length 75) were mixed by air blowing at a ratio of 80:20 by weight, a web was produced using a carding machine as shown in Figure 2, and then laminated and needle punched to make felt. Obtained. Web yield was approximately 80%.

The weight of the obtained felt was approximately 500 g/nf, and the thickness and density were uniform.

Example 5 Pitch-based CF obtained by centrifugally spinning fiber-forming pitch, infusible and carbonized (average diameter 18μ, average tensile strength 60k)
g/am'', average tensile modulus of elasticity 3 ton/sm'), and was pre-opened to obtain a single yarn mass with an average fiber length of 60 mm.

This is combined with acrylic flame-resistant Pyromex (trade name of flame-resistant yarn made from acrylic fiber sold by Toho Rayon Co., Ltd.).
Average diameter 14μ, average tensile strength 17 kg/wr”
.

20% elongation and 75% average fiber length) were mixed by air blowing at a ratio of 80:20 by weight, and a web was produced using a carding machine (not shown in Figure 2), followed by lamination and needle punching. The felt was then carbonized at a maximum temperature of 900°C. Web yield was approximately 80%. The weight of this felt was approximately 500 g/rd, and the thickness and density were uniform.

Comparative Example 1 The pitch-based CF used in Example 2 was mixed with the aforementioned Kynol fiber at a weight ratio of 95:5, and the mixture was run through the carding machine shown in FIG. 2 to obtain a carded web. However, some of the shortened CF fell onto the lower floor of the take-in roller 3 and the dosing roller 8, and the yield of the web was only about 60% at most. Furthermore, since the fibers constituting the web itself were short, the web itself had only enough strength to break under its own weight.

Comparative Example 2 Next, the pitch-based CF used in Example 2 was mixed with the aforementioned Kynol fiber at a weight ratio of 55:45.
A carded web was obtained using the carding machine shown in the figure, followed by lamination, needle punching, and carbonization at a maximum temperature of 900°C to obtain felt. The web yield was 85%. However, this felt was deformed due to the shrinkage of the Kynol fibers, and did not have a uniform thickness, resulting in large variations in area weight and significantly impairing moldability.

The Examples and Comparative Examples are shown in Table 1.

<Effects of the Invention> As explained above, in the method for producing carbon fiber felt of the present invention, fibrous aggregates made of pitch-based carbon materials in various forms obtained after spinning, infusibility, and pre-gI carbonization,
Specify other carbon precursor fibers! By mixing it, it is possible to stably produce a uniform felt whose main component is pinch type carbon fiber, which is a raw material for various carbon fiber products such as heat insulating materials, C/C materials, and activated carbon fibers.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram of a card machine that can be used in the present invention, and FIG. 2 is a schematic diagram of a felt manufacturing apparatus that can be used in the present invention. l... Conveyor 2... Feed roller 3... Take-in roller 14... Roller card, 5... Stripper 6... Cylinder 7.
...Metallic wire, 8...Dotsfa-9...
Comber 10... Calendar roller 11... Auto feeder, 12... Wrapping device, 13...
Needle bunch device, 14... Raw carbon fiber (mixed fiber), 15... Card web, 16... Carbon fiber felt. Patent applicant: Kawasaki Steel Corporation

Claims (3)

[Claims] 1. The weight ratio of fibers made of a carbon precursor other than pitch to a fiber aggregate made of a pitch-based carbon material is 9:1 to 6:4.
Pitch-based carbon fibers are mixed into the pitch-based carbon fibers to reduce the frictional resistance between the pitch-based carbon fibers, and then the mixed webs are laminated and bonded by physical or mechanical action. A method for producing blended felt as a component. 2. The production of a blended felt mainly composed of pitch-based carbon fibers according to claim 1, characterized in that a phenol-based flame-resistant yarn or a polyacrylonitrile-based flame-resistant yarn is used as the fiber made of a carbon precursor other than pitch-based fibers. Method. 3. 3. The method for producing a blended felt containing pitch-based carbon fiber as a main component according to claim 1 or 2, further comprising subjecting the blended felt to a carbonization treatment.