JPH11246248A - Carbon fiber bundle, carbon fiber reinforced calcium silicate molding and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a bundle of carbon fibers excellent in dispersibility in a calcium silicate matrix and to produce a carbon fiber reinforced calcium silicate molding excellent in heat resistance and mechanical strength because of uniformly dispersed reinforcing fibers by using the bundle. SOLUTION: Carbon fibers obtd. by heat-treating polyacrylonitrile fibers as starting material and having >=90% carbon content, a peak ratio O1s/C1s (oxygen content to carbon content) of 0.01 to <0.1 measured by the electron spectroscopy for chemical analysis(ESCA) method and 1-30 mm fiber length are bundled with a glycerol bundling agent to obtain the objective bundle of carbon fibers excellent in dispersibility in a calcium silicate matrix. When the bundle is used, the objective carbon fiber reinforced calcium silicate molding excellent in heat resistance and mechanical strength is obtd.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a carbon fiber bundle for reinforcing a calcium silicate molded article which is excellent in handleability and dispersibility in a calcium silicate matrix, heat resistance and mechanical properties using the carbon fiber bundle. The present invention relates to a carbon fiber reinforced calcium silicate molded article having excellent properties and a method for producing the same.

[0002]

2. Description of the Related Art Molded products containing calcium silicate as a matrix have properties such as excellent fire resistance, nonflammability, heat resistance, water resistance, and dimensional stability at high temperatures. Insulating materials for buildings and heat-resistant sealing materials for automobiles,
It is widely used for materials such as molds for metal casting.

[0003] As a method for producing a calcium silicate molded product, a calcium silicate aqueous slurry prepared by using a calcareous raw material and a siliceous raw material as a matrix material and adjusting the molar ratio of CaO to SiO ₂ to be substantially equal is used. By adding a molecular coagulant, the fine particles in the slurry are coagulated and precipitated (gelled), and then the coagulated precipitate is collected, depressurized and formed into a predetermined shape, and then heated at a temperature of 160 ° C. or more. A method of obtaining a calcium silicate molded product by heating (high-temperature heat treatment) is generally used.

[0004] In the calcium silicate molded product thus obtained, the shape change during the high-temperature heat treatment is large, and the obtained calcium silicate molded product has low mechanical properties. A method has been proposed in which carbon fibers or inorganic reinforcing fibers are contained in a matrix for the purpose of preventing the change in shape during high-temperature heat treatment (for example, JP-A-61-232256,
JP-A-62-187153, JP-A-64-382
See Japanese Patent Publication No. 27, JP-B 8-18397. ).

Glass fibers and the like have been initially used as reinforcing fibers for reinforcing calcium silicate molded products. However, in view of dimensional stability and heat resistance of molded products, carbon fibers have recently been widely used. It has become. For example, a general carbon fiber is used for reinforcing a calcium silicate molded product, and a short fiber cut to about 10 mm is generally used at a content of 0.5 to 10% by weight based on a matrix. It is a target.

When carbon fiber is used as a reinforcing fiber for a calcium silicate molded product, the carbon fiber has excellent mechanical properties such as high heat resistance, high strength and high elastic modulus. A matrix body containing calcium silicate as a main component exhibits an excellent reinforcing effect and heat resistance because of its excellent adhesion to calcium. Therefore, calcium silicate matrix molded articles reinforced with carbon fibers are used, in particular, as refractory building materials or molds for casting of metals such as aluminum, zinc, tin and lead.

[0007] When reinforcing a calcium silicate matrix molded article using carbon fibers as reinforcing fibers, what is desired is to improve the heat resistance effect and the reinforcing effect by using a single fiber 1 of a short fibrous carbon fiber bundle. One of them is effectively dispersed in the calcium silicate matrix without entanglement. That is, by uniformly dispersing carbon fibers in a calcium silicate matrix, it is possible to prevent a deterioration phenomenon such as crack generation due to a thermal shock caused by local heating and to form a uniform reinforcing structure. .

In this respect, many attempts have been made to reinforce the calcium silicate molded product by optimizing the content of the carbon fiber in the calcium silicate matrix molded product, the dispersion method, the type of carbon fiber and the sizing agent, and the like. (For example, JP-A-55-126565, JP-A-61-3614)
No. 7).

By the way, carbon fiber is a material generally well known as a reinforcing fiber of a resin molded product. Generally, carbon fibers are fibers obtained by firing organic fibers such as acrylonitrile-based fibers and pitch fibers as raw materials, and are mostly made of carbon. This carbon fiber does not change its properties such as thermal decomposition even in a high temperature range of 1000 ° C. or more in a non-oxidizing atmosphere, and has a strand tensile strength of 200 kgf / mm ² or more and a tensile elastic modulus of 2 or more.
Since it exhibits excellent mechanical properties of 0 tonf / mm ² or more, it is widely used as a reinforcing fiber.

The carbon fiber having the above properties is often used as a reinforcing material for a high-molecular organic matrix molded product in the form of long fibers or short fibers obtained by cutting long fibers.
When used in the form of a long fiber, it is used in the form of a sheet, woven fabric, non-woven fabric or the like arranged in one direction. When used in the form of short fibers, they are used in the form of fiber bundles bundled in a bundle with a resin or the like in order to enhance the handleability.

Carbon fiber used as a reinforcing material for a resin molded article has been subjected to a treatment for improving the wettability with the matrix resin in order to improve the affinity with the matrix resin. This treatment is called a surface treatment, and usually oxidizes the surface of the carbonized carbon fiber in order to impart a functional group such as a carboxylic acid group or a hydroxyl group to the carbon fiber surface.

The degree of the number of functional groups imparted to the surface of the fiber by this surface treatment is determined by ESC which is a surface analyzer.
Using a device called A (X-ray photoelectron spectroscopy), the ratio of the oxygen content to the carbon content existing near the surface (O1s /
C1s value) is estimated and evaluated.

Under such ordinary process conditions, the O1s / C1s value of the surface-treated carbon fiber is 0.1 or more.
It is within 0.3, and this value increases as the number of functional groups such as carboxylic acid groups and hydroxyl groups increases.

Usually, the number of dried filaments is 1000
If the carbon fiber bundle is more than one, the strands will not be cohesive,
Due to the property that it is easily spread by wind and the like, and is difficult to handle, water or oil such as higher alcohol, or highly viscous substance such as epoxy resin is used as a sizing agent, and 1 to 10 weight of carbon fiber. %, The strands are put together to improve the handleability.

[0015] Further, depending on the use of the carbon fiber, it is also known to treat the carbon fiber with a water-soluble polymer substance such as PVA or PEG as a hydrophilic sizing agent. The purpose of the treatment with these water-soluble substances is, for example, to improve the water dispersibility in papermaking using short fibers of carbon fibers.

However, the carbon fiber bundles bundled with these conventional water-soluble polymer sizing agents, when mixed in a calcium silicate matrix, have poor dispersibility of the carbon fibers and do not spread evenly. The obtained carbon fibers had a non-uniform distribution as a bundle in the calcium silicate molded product, and thus had poor mechanical properties and heat resistance.

The mixing ratio of carbon fibers to the calcium silicate matrix also varies depending on the purpose of use and conditions. Since it is difficult to uniformly disperse the fibers and the carbon fibers are present in a lump in the molded product, the reinforcing effect accompanying the fiber content cannot be sufficiently exhibited even if the content is increased.

[0018]

SUMMARY OF THE INVENTION An object of the present invention is to provide a carbon fiber bundle having excellent dispersibility in a calcium silicate matrix.

Another object of the present invention is to provide a carbon fiber reinforced calcium silicate in which a reinforcing fiber is uniformly dispersed by using such a carbon fiber bundle having excellent dispersibility, and thus has excellent heat resistance and mechanical strength. An object of the present invention is to provide a molded product and a method for producing the same.

[0020]

SUMMARY OF THE INVENTION The present invention provides a carbon fiber in which the surface treatment of the carbon fiber is moderate and the number of functional groups on the surface of the carbon fiber is kept low. On the other hand, by using a carbon fiber bundle having a fiber length of 1 mm or more and 30 mm or less with the glycerin sizing agent attached to the strands, the carbon fibers are less entangled in the mixed state in the calcium silicate slurry. Specifically, the present invention provides a molded product in which carbon fibers are uniformly dispersed in a calcium silicate matrix.

That is, the carbon fiber bundle of the present invention for achieving the above-mentioned object is obtained by heat-treating polyacrylonitrile fiber as a raw material.
The peak ratio of O1s / C1s measured by the CA method is 0.01 or more and less than 0.1, and the fiber length is 1 mm or more and 30 mm.
Wherein the carbon fiber bundle is bundled with a glycerin sizing agent.

The present invention also relates to a carbon fiber reinforced calcium silicate molded article using the carbon fiber bundle as a reinforcing fiber, wherein (1) the matrix material is calcium silicate, and (2) the reinforcing fiber is Acrylonitrile fiber obtained by heat treatment as a raw material, carbon content of 90% or more,
The peak ratio of O1s / C1s measured by the ESCA method is 0.01 or more and less than 0.1, and the fiber length is 1 mm or more and 30 m.
It is a carbon fiber reinforced calcium silicate molded product characterized in that the carbon fiber has a diameter of not more than m.

The present invention also relates to a method for producing a carbon fiber-reinforced calcium silicate molded product, comprising a calcareous raw material and a siliceous raw material as a main raw material having a solid content concentration of 1% by weight or more.
After mixing the carbon fiber bundle in an aqueous slurry of 0% by weight or less, the aqueous slurry is coagulated and precipitated with a polymer coagulant, and the precipitate is subjected to dehydration, shaping, and heat treatment. And a method for producing a carbon fiber reinforced calcium silicate molded article having excellent mechanical properties.

The carbon fiber bundle of the present invention is easily dispersed uniformly in the slurry by adding it to an aqueous slurry of an inorganic matrix containing calcium silicate as a main component and stirring the resulting mixture to obtain a finally obtained molded product. Has the effect of increasing the reinforcing effect and heat resistance effect. That is, according to the present invention, since the treated carbon fibers are uniformly dispersed in the calcium silicate matrix, the heat conductivity of the obtained molded product is uniform, and the thermal shock accompanying local heating is obtained. Deterioration phenomena such as cracks caused by (thermal shock) are relatively small, and a carbon fiber reinforced calcium silicate molded article having excellent heat resistance and mechanical strength is obtained.

[0025]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIGS. 1 and 3 are photographs showing a dispersion state of carbon fibers in an example of a calcium silicate molded article reinforced by using a carbon fiber bundle of the present invention. For comparison, FIG. 2 shows a photograph showing the dispersion state of carbon fibers in a molded product not according to the present invention, that is, a molded product having an O1s / Cls ratio outside the range of the present invention. FIG. 4 is a photograph showing the state of dispersion of carbon fibers in a molded article obtained by using the molded article.

In FIG. 1 to FIG. 4, what looks linear is the carbon fiber, and what looks black and solid is the portion where the carbon fiber aggregates. As can be seen from FIGS. 1 to 4, the carbon fiber reinforced calcium silicate molded product of the present invention has extremely good dispersibility of carbon fiber, whereas the comparative carbon fiber reinforced calcium silicate molded product has a carbon fiber dispersibility. Poor fiber dispersibility.

The carbon fiber used as a raw material of the carbon fiber bundle of the present invention is not particularly limited, but polyacrylonitrile fiber is prepared by subjecting a polyacrylonitrile fiber to an inert gas atmosphere of 1,000 to 3,000.
So-called acrylic carbon fibers made by firing at ℃ are suitable. In addition, a well-known method can be applied to the method for producing the acrylic carbon fiber.

The ordinary acrylic carbon fiber obtained by the above-mentioned known method has a filament single fiber diameter of 3 to 3.
10 μm, fiber specific gravity 1.6 to 2.0, tensile strength of strand formed by bundling filaments 250 to 8
00 kfg / mm ² , tensile modulus of strand 20
８０80 tonf / mm ² , and the peak ratio of O1s / C1s measured by the ESCA method is 0.1 or more and 0.3 or less.

With respect to this ordinary carbon fiber, the peak ratio of O1s / C1s measured by the ESCA method is set to 0.0
In order to make it 1 or more and less than 0.1, the carbon fiber should be 100
This can be achieved by baking at 0 to 3000 ° C., and then cooling to a temperature of 400 ° C. or lower under an inert gas atmosphere, and then performing a light surface treatment. Alternatively, O1s measured by the ESCA method by a method other than the surface treatment step
The peak ratio of / C1s can be 0.01 or more and less than 0.1.

For example, even in the case of carbon fibers from which the above-mentioned surface treatment step has been omitted, when exposed to an air atmosphere at a temperature exceeding 400 ° C., a chemical reaction occurs with oxygen in the air and O 2
Since the peak ratio of 1 s / Cls may exceed the range of 0.01 or more and less than 0.1, exposure of the carbon fiber to an air atmosphere exceeding 400 ° C. must be avoided.

The surface treatment of the carbon fiber for setting the peak ratio of O1s / Cls to 0.01 or more and less than 0.1 includes strong acids such as sulfuric acid and nitric acid or salts of strong acids, acetic acid, and hypochlorous acid. A method in which the carbon fiber bundle is immersed in a solution of a weak acid or a salt of a weak acid such as described above, or an alkali or an alkali salt such as sodium hydroxide or potassium hydroxide or the like is applied.

Further, at the time of this surface treatment, electricity may be supplied to the carbon fiber bundle to perform electrolytic oxidation. Alternatively, a method in which a carbon fiber bundle is brought into contact with a gas such as ozone or halogen to perform an oxidation treatment can also be applied. Electrolytic reduction treatment can also be performed on carbon fibers that have undergone oxidation treatment.

In each case, carbon fiber ESC
The peak ratio of O1s / Cls measured by Method A is 0.
It is necessary to set the concentration of the processing solution, the temperature, the amount of electricity, the concentration of the gas, the processing time, and the like so as to fall within the range of 01 or more and less than 0.1.

In the present invention, the glycerin sizing agent refers to a mixed solution of glycerin alone and glycerin as a main component and water containing at least 50% by weight of glycerin in the sizing agent. In particular, it is preferable to use an aqueous solution having a glycerin content of 50 to 80% by weight in order to improve the dispersibility of the carbon fiber bundle in the calcium silicate slurry.

For the application of the glycerin sizing agent to the carbon fiber, a general application of a sizing agent usually applied to the carbon fiber can be employed. That is, the continuous carbon fiber is immersed in the glycerin sizing agent and then dried. Alternatively, the method is not particularly limited, such as a spray method, a roller transfer method, and a lip method. After the glycerin sizing agent is applied, the fiber is cut into a desired fiber length to obtain a carbon fiber bundle of 1 mm to 30 mm.

In order to reinforce the calcium silicate matrix using the carbon fiber bundle of the present invention, for example, the following conventional method can be employed as it is. That is, the carbon fiber bundle of the present invention is not only dispersible in the calcium silicate slurry, but also satisfies the affinity with the calcium silicate matrix. A calcium silicate molded article having excellent properties and heat resistance can be obtained.

[0037]

[Example 1] A carbon fiber strand obtained by subjecting an acrylonitrile fiber to a flame-proofing treatment and a carbonization treatment at a maximum temperature of 1300 ° C by an ordinary method was subjected to ammonium sulfate in a subsequent carbon fiber surface treatment step. The carbon fiber was immersed in the solution and subjected to electrolytic surface treatment to obtain a carbon fiber having a O1s / Cls peak ratio of 0.08 on the surface of the carbon fiber measured by the ESCA method. The number of filaments per strand is 12,000, the diameter of a single fiber is 7 μm, the specific gravity of the fiber is 1.75, and the strand tensile strength is 350 kgf / m.
m ² .

The carbon fiber bundle was introduced and immersed in a bath in which a solution having a weight ratio of glycerin / water of 10/90 was circulated, and the solution was adhered to the bath, followed by drying at 150 ° C. for 5 minutes. The obtained carbon fiber bundle was cut to obtain a chopped strand of short carbon fiber having a fiber length of 6 mm. The weight percent of the glycerin sizing agent attached to the chopped strand was 5.0
% And the water content were 2.5%.

After adding a small amount of a silicic acid-based additive to a slurry-like solution having a weight ratio of calcium silicate / water of 1/8,
The carbon fiber chopped strand obtained in the above step was added at 2% based on the solid content of calcium silicate, and the mixture was stirred for 1 hour. Then, an acrylamide polymer flocculant was added at 3% based on the solid content of calcium silicate. Mixed.

When this slurry-like solution was poured into a female mold and allowed to stand, the solution was gelled by the coagulant, and the calcium silicate was coagulated, solidified and precipitated. Insert a male mold from the top of the mold, dehydrate under pressure at a pressure of about 3 kg / cm ² to remove water, then dry at 150 ° C., take out from the mold,
A preform of calcium silicate was obtained. The obtained preform was heat-treated at a temperature of 300 to 500 ° C for 1 to 5 hours to obtain a calcium silicate formed product.

The surface of the obtained molded product was polished with a No. 1000 sandpaper. FIG. 1 shows a photograph showing the dispersion shape of the fibers floating on the surface of the molded product. When the dispersion state of the carbon fiber bundles contained in the molded product was visually observed, the surface of the molded product showed good dispersibility of the carbon fibers as shown in FIG. It was a little thing.

The bending strength of the molded product is 130 kgf / cm ²
And was good. Also, after making a cut of about 1 cm in the molded product with a cutter, it was heat-treated at 800 ° C. for 3 hours in the air. It could be confirmed.

Comparative Example 1 In the surface treatment step of carbon fiber, the same procedure as in Example 1 was performed except that the carbon fiber was immersed in a 10% ammonium sulfate solution, and the carbon fiber was subjected to electrolytic surface treatment at an electric quantity of 15 C / g. The same conditions were followed to obtain carbon fibers. The peak ratio of O1s / Cls on the surface of the obtained carbon fiber measured by ESCA was 0.20.

The number of filaments per strand is 12,
000 fibers, single fiber diameter 7 μm, specific gravity of fiber 1.7
5. The strand tensile strength was 370 kgf / mm ² , which was not different from that of Example 1.

Glycerin was adhered in the same manner as in Example 1 to obtain a short fiber chopped strand having a fiber length of 6 mm. A molded product of calcium silicate was produced in the same manner as in Example 1. FIG. 2 shows a photograph showing the dispersion shape of the fiber floating on the surface of the molded product. The dispersion state of the carbon fiber bundle contained in the molded product was visually observed.

As shown in FIG. 2, the surface of the molded product had poor carbon fiber dispersibility, a portion where the carbon fiber was coagulated and solidified black, and the flexural strength of the molded product was 110 kgf / cm.
^{In 2} , the mechanical strength was slightly lower than that in Example 1.

When a cut of about 1 cm was made in the molded product with a cutter and then heat-treated in air at 800 ° C. for 3 hours, large crack growth was observed from the cut of the cutter due to the heat treatment. The results are shown in Table 1 below.

Example 2 A carbon fiber was obtained by performing the same treatment as in Example 1 except that in the surface treatment step of the carbon fiber, a sample was collected without performing the electrolytic surface treatment. The peak ratio of O1s / Cls on the carbon fiber surface of the carbon fiber measured by the ESCA method was 0.05.
The number of filaments per strand was 12,000, the diameter of a single fiber was 7 μm, the specific gravity of the fiber was 1.75, and the strand tensile strength was 340 kgf / mm ² .

Glycerin was adhered in the same manner as in Example 1 to obtain a short fiber chopped strand having a fiber length of 6 mm. FIG. 3 shows a photograph showing the dispersion shape of the fiber floating on the surface of the molded product. A calcium silicate molded product was produced in the same manner as in Example 1, and the dispersion state of the carbon fiber bundle contained in the molded product was visually observed. Fig. 3
As shown in (1), the dispersibility of the carbon fiber was good, and the carbon fiber was uniformly dispersed in a filament in the molded product.

The bending strength of the molded product is 125 kgf / cm ²
The mechanical strength was almost the same as that of Example 1. Also, after making a cut of about 1 cm in the molded product with a cutter, and heat-treated at 800 ℃ in air for 3 hours,
Due to the heat treatment, the amount of crack generation from the cut portion of the cutter was small. The results are shown in Table 1 below.

[Comparative Example 2] A sample of carbon fiber produced under the same conditions as in Example 1 was collected and introduced into a bath in which a 2% by weight aqueous solution of polyvinyl alcohol was circulated as a sizing agent. And dried at 120 ° C. The obtained carbon fiber bundle was cut to obtain a short fiber chopped strand having a fiber length of 6 mm. The amount of polyvinyl alcohol attached to the chopped strand was 1.0%.

A molded product of calcium silicate was produced in the same manner as in Example 1. FIG. 4 shows a photograph showing the dispersion shape of the fiber floating on the surface of the molded product. The dispersion state of the carbon fiber bundle contained in the molded product was visually observed. As shown in FIG. 4, poor dispersibility of carbon fibers was observed on the surface of the molded product, and the molded product was non-uniform. The bending strength of the molded product was 105 kgf / cm ² , and a large crack generation phenomenon was recognized in the thermal shock test. The results are shown in Table 1 below.
Shown in

Examples 3 to 6 Carbon fiber strands having different carbon fiber production conditions and electrolytic surface treatment conditions shown in Table 1 below, and O1s / C1s measured by the ESCA method within the scope of the present invention. Using a carbon fiber strand having each value of the peak ratio, a calcium silicate molded product was produced under the same conditions as in Example 1, and the dispersion state of the carbon fiber bundle, the bending strength of the molded product, and the state of crack generation due to heat treatment were measured. investigated. The results are shown in Table 1 below.

[Comparative Examples 3 to 5] A calcium silicate molded product was produced under the same conditions as in Example 1 above, using carbon fiber production conditions, electrolytic surface treatment conditions, and carbon fiber chopped strands having different sizing agents for sizing the carbon fibers. The prepared carbon fiber bundle was dispersed, the bending strength of the molded product, and the state of crack generation due to heat treatment were investigated. The results are shown in Table 1 below.

[0055]

[Table 1]

As shown in Table 1, the carbon fiber reinforced calcium silicate molded products of Examples 1 to 6 were excellent in the dispersibility and bending strength in the molded products, and the occurrence of cracks was small. On the other hand, in the carbon fiber reinforced calcium silicate molded products of Comparative Examples 1 to 4, the peak ratio of O1s / C1s measured by the ESCA method is out of the range of the present invention, or the sizing agent of the present invention is used. Or the fiber length is out of the range of the present invention, or the reinforcing fiber is not used, so that the dispersibility and flexural strength of the carbon fiber in the obtained molded product are slightly inferior, and cracks are generated. The frequency was high.

[0057]

Advantages of the Invention When the carbon fiber bundle of the present invention is dispersed in a calcium silicate slurry, the carbon fiber bundle is easily dispersed by stirring, and a slurry in which individual filaments are uniformly spread in the slurry is obtained.

2. After the calcium silicate slurry is gelled with a polymer coagulant, the molded product obtained by pressure dehydration molding and heating is uniformly dispersed in the calcium silicate matrix by using the carbon fiber bundle of the present invention. A dispersed molded product is obtained.

3. The calcium silicate molded product of the present invention obtained by the heat treatment has excellent mechanical properties such as bending strength and also has excellent thermal shock properties.

4. The calcium silicate molded product of the present invention,
Even when the carbon fiber bundle of the present invention is contained in an amount of 1% by weight or more based on the solid content of calcium silicate, the carbon fibers can be uniformly dispersed in the calcium silicate matrix.

[Brief description of the drawings]

FIG. 1 is a photograph showing a dispersed shape of carbon fibers in an example of a calcium silicate molded article reinforced using a carbon fiber bundle of the present invention.

FIG. 2 shows a molding not according to the invention, ie O1s / Cl
It is a photograph which shows the dispersed shape of the carbon fiber in the molded object whose s ratio was outside the range of the present invention.

FIG. 3 is a photograph showing a dispersed shape of carbon fibers in an example of a calcium silicate molded article reinforced using the carbon fiber bundle of the present invention.

FIG. 4 is a photograph showing a dispersed shape of carbon fibers in a molded product using a sizing agent other than that of the present invention.

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Takahiro Hayashi 3-3-9 Nihonbashi, Chuo-ku, Tokyo Inside Toho Rayon Co., Ltd.

Claims (8)

[Claims] An ESCA having a carbon content of 90% or more obtained by heat-treating polyacrylonitrile fiber as a raw material.
The peak ratio of O1s / C1s is 0.0
A carbon fiber bundle, which is a carbon fiber bundle having a length of 1 to less than 0.1 and a fiber length of 1 mm to 30 mm, and wherein the carbon fiber bundle is bundled with a glycerin sizing agent. 2. The carbon fiber bundle according to claim 1, wherein the glycerin sizing agent is an aqueous glycerin solution. 3. The carbon fiber bundle according to claim 2, wherein the concentration of the glycerin aqueous solution is 50% by weight or more. 4. The weight percent of the glycerin sizing agent attached to the carbon fiber bundle is 1% by weight based on the weight of the carbon fiber.
The carbon fiber bundle according to claim 1, which is the above. 5. The carbon fiber bundle has a diameter of 3 μm or more,
The carbon fiber bundle according to claim 1, wherein a single fiber of 000 or more carbon fibers is bundled. 6. The carbon fiber bundle is formed by bundling single fibers of carbon fibers having a diameter of 3 μm or more, a tensile strength of 250 kgf / mm ² or more, and a tensile elasticity of 20 tonf / mm ² or more. Carbon fiber bundle. 7. A matrix material containing (1) calcium silicate as a main component, and (2) a carbon fiber content of at least 90% obtained by heat-treating a reinforcing fiber using polyacrylonitrile fiber as a raw material. ES
The peak ratio of O1s / C1s measured by the CA method is 0.01 or more and less than 0.1, and the fiber length is 1 mm or more and 30 mm.
A carbon fiber reinforced calcium silicate molded product, characterized in that the carbon fiber is within: 8. The carbon fiber bundle according to claim 1, which is mixed with an aqueous slurry containing a calcareous material and a siliceous material as main materials and having a solid content concentration of 1% by weight or more and 20% by weight or less. A method for producing a carbon fiber reinforced calcium silicate molded product, comprising coagulating and precipitating an aqueous slurry with an agent, and subjecting the precipitate to dehydration, shaping and heat treatment.