KR20110036531A - Nonwoven fabric, felt and manufacturing method thereof - Google Patents

Abstract

An object of the present invention is to provide a nonwoven fabric containing a pitch-based carbon fiber having a high elongation and a high modulus of elasticity, which is conventionally improved, by improving tensile elongation, which is a drawback of carbon fibers derived from mesophase pitch. The present invention is a nonwoven fabric containing pitch-based carbon fibers, wherein the pitch-based carbon fibers have an average fiber diameter (D1) observed by an optical microscope of greater than 2 µm and 20 µm or less, and (ii) an optical microscope. 100% of the fiber diameter dispersion (S1) relative to the average fiber diameter (D1) is 3 to 20%, (iv) tensile modulus is 80 to 300 kPa, and (iv) tensile elongation is 1.4 to 2.5%, characterized in that It is a nonwoven fabric, the felt which consists of this nonwoven fabric, and their manufacturing method.

Description

NONWOVEN FABRIC, FELT AND MANUFACTURING METHOD THEREOF

The present invention relates to a nonwoven fabric containing pitch-based carbon fibers having high elongation and elastic modulus, felts therefrom, heat insulating materials, and methods for producing them. More specifically, the present invention relates to a nonwoven fabric containing pitch-based carbon fibers infused and calcined under specific conditions using mesophase pitch as a raw material, and a felt and a heat insulating material excellent in durability and oxidation resistance therefrom.

Carbon fibers made of polyacrylonitrile as raw materials have balanced strength and elastic modulus, and are widely used as structural members for industrial robot arms and aircraft. In order to further expand the use of carbon fiber as an automobile member or the like, it is necessary to reduce the cost. However, since the starting material of carbon fiber which uses polyacrylonitrile as a raw material is synthetic resin, there exists a limit in reducing cost.

As low-cost carbon fibers, there are pitch-based carbon fibers whose pitch is a residue of petroleum or coal. Pitch-type carbon fiber can be divided roughly into the carbon fiber which uses isotropic pitch as a raw material, and the carbon fiber which uses mesophase pitch as a raw material.

Pitch-based carbon fiber which uses isotropic pitch as a raw material becomes a high elongation carbon fiber whose elongation exceeds 2%, for example as described in patent document 1. On the other hand, however, the graphitization property is low, and it has the drawback that carbon fiber of high elastic modulus cannot be obtained. On the other hand, carbon fibers made from mesophase pitches can easily achieve high modulus of elasticity because of their excellent graphitization. However, although high elastic modulus can be achieved by development of graphite crystal by high temperature baking, elongation falls and, as a result, there exists a fault that intensity falls. Therefore, it was very difficult to produce pitch-based carbon fibers having high elongation and high elastic modulus.

As a means for solving these problems, the method of modifying a raw material pitch is proposed. For example, Patent Literature 2 polymerizes a condensed polycyclic hydrocarbon at 100 to 400 ° C in the presence of hydrogen fluoride and boron trifluoride to obtain a pitch of less than 5% optically anisotropic content, and then thermally polymerizes at 250 to 450 ° C. The raw material which the atomic ratio of hydrogen to carbon obtained is 0.5-0.7, the amount of oriented carbons in all aromatic carbon is 50% or less, 5-60 micrometers of anisotropic spheres is 5 to 60%, and pyridine insoluble content is 25 weight% or less. However, since this method uses strong acids such as hydrogen fluoride and boron trifluoride for the catalyst, it is necessary to use a special equipment, and there is a problem in that the waste acid extracted after the reaction is enormously expensive.

In addition, Patent Document 3 discloses a method for producing carbon fibers using a reactant obtained by reacting a crosslinking agent with a mesophase pitch as a raw material. However, this method also has a problem such as high cost since a special crosslinking agent is used.

As another method of improving the strength of pitch-based carbon fibers, Patent Document 4 discloses a method for producing pitch-based carbon fibers in which pitch fibers are contained with iodine in the absence of oxygen, and then heat treated in an inert atmosphere. However, this method has the drawback that iodine adsorbed to the pitch in the carbonization step is released, and as a result, the life of the furnace is significantly reduced.

Further, Patent Document 5 applies a tension at 700 ° C. or lower in an inert atmosphere to heat the mixture under tension under tension in a inert atmosphere, and then heats the incompatible fiber in an inert atmosphere. Carbonization and graphitization methods have been proposed. However, this method is possible when the carbon fiber precursor is long fiber, but there is a problem that the carbon fiber precursor produced by, for example, the melt blow method cannot be adopted because it becomes a nonwoven fabric.

Further, Patent Document 6 discloses a carbon fiber in which an incompatibility treatment is performed at an temperature range of 100 to 400 ° C. under an oxidizing atmosphere containing 0.1 to 40% by volume of NO ₂ and 4 to 40% by volume of H ₂ O. The manufacturing method of is introduced. However, in this method, as described in the examples, the results were lowered in terms of elastic modulus.

As described above, it was very difficult to produce pitch-based carbon fibers having high elongation and high elastic modulus.

Japanese Patent Laid-Open No. 2-169727 Japanese Patent Laid-Open No. 9-279154 Japanese Unexamined Patent Publication No. Hei 1-207420 Japanese Patent Application Laid-open No. Hei 8-27628 Japanese Laid-Open Patent Publication No. 62-69826 Japanese Patent Laid-Open No. 2-6618

As described above, the carbon fiber made of mesophase pitch has excellent elastic modulus, but the tensile elongation is lower than that of the carbon fiber made of isotropic pitch, which makes it difficult to develop an industrial robot arm or a structural member of an aircraft. There was a problem.

Accordingly, an object of the present invention is to provide a nonwoven fabric containing a pitch-based carbon fiber having a high elongation and a high modulus of elasticity, which is conventionally improved, by improving tensile elongation, which is a drawback of carbon fibers derived from mesophase pitch. Moreover, the objective of this invention is providing the felt which gave the needle punch process to the nonwoven fabric containing pitch-type carbon fiber which has high elongation and elastic modulus, and the heat insulating material from it.

MEANS TO SOLVE THE PROBLEM In the infusible process of the carbon fiber manufacturing process which uses mesophase pitch as a raw material, this inventor manufactured the infusible fiber whose oxygen addition amount is 8-15 weight%, and it baked at 800-1,800 degreeC, and tensile elongation improved. The present invention has been found by finding that a nonwoven fabric containing a pitch-based carbon fiber having high elongation and high elastic modulus, which has not been conventionally obtained, is obtained.

That is, this invention includes the following inventions.

1. A nonwoven fabric containing pitch carbon fibers, wherein the pitch carbon fibers are

(Iii) the average fiber diameter (D1) observed with an optical microscope is larger than 2 µm and not larger than 20 µm,

(Ii) 100% of fiber diameter dispersion (S1) with respect to average fiber diameter (D1) observed with the optical microscope is 3 to 20%,

(Iii) a tensile modulus of 80 to 300 GPa, and

(Iv) Tensile elongation is 1.4 to 2.5%, The nonwoven fabric characterized by the above-mentioned.

2. The nonwoven fabric of the said Item | item 1 whose tensile elasticity modulus of pitch-type carbon fiber is 100-300 GPa, and tensile elongation is 1.5 to 2.4%.

3. The nonwoven fabric of the said claim | item 1 whose average fiber diameter (D1) observed with the optical microscope of pitch-type carbon fiber is larger than 10 micrometers and 20 micrometers or less.

4. The nonwoven fabric according to the above item 1, wherein the tensile strength is 10 N / 5 cm piece or more.

5. (1) spinning a mesophase pitch to prepare a precursor web containing a carbon fiber precursor,

(2) dissolving the precursor web in an oxidizing gas atmosphere to produce an infusible web containing carbon fibers having an oxygen addition amount of 8 to 15% by weight, and

(3) firing the incompatible web at 800 to 1,800 ° C;

The manufacturing method of the nonwoven fabric containing each process.

6. The production method according to item 5, wherein the spinning is performed by a melt blow method.

7. The production method according to item 5, wherein the average fiber length of the carbon fiber precursor of the precursor web is 4 to 25 cm.

8. The manufacturing method of said item 5 whose oxygen addition amount of the carbon fiber of an infusible web is 9-12 weight%.

9. The manufacturing method of said item 5 whose fiber length retention (%) represented by following formula (I) before and after baking is 90% or more.

Fiber Length Retention Rate = 100 × L ¹ / L ⁰ (Ⅰ)

L ⁰ : fiber length before firing

L ¹ : fiber length after firing

10. Felt obtained by needle punching the nonwoven fabric of Claim 1.

11. The felt according to item 10, wherein the interlayer peel strength in the thickness direction is 0.25 N / 5 cm piece or more.

12. The felt according to item 10, wherein the average fiber diameter of the carbon fibers is larger than 10 µm and equal to or less than 20 µm, and the apparent weight is 250 to 1,000 g / m 2.

13. Graphitized felt obtained by heat-processing the felt of said claim | item 10 at 2,000-3,500 degreeC.

14. (1) spinning a mesophase pitch to prepare a precursor web containing a carbon fiber precursor,

(2) infusing the precursor web in an oxidizing gas atmosphere to produce an infusible web containing carbon fibers having an oxygen addition amount of 8 to 15% by weight,

(3) firing the incompatible web at 800 to 1,800 ° C. to produce a nonwoven fabric, and

(4) needle punching the nonwoven fabric,

The manufacturing method of the felt containing each process.

15. The manufacturing method according to item 14, wherein the nonwoven fabric is needle punched with a punch number of 15 to 100 times / cm 2 with a needle having a barb depth of 0.15 mm or more.

16. A composite obtained by impregnating a resin in the felt according to item 10.

17. A composite obtained by impregnating a resin in the graphitized felt according to item 13 above.

18. The heat insulating material obtained by heat-processing the composite of said claim 16 at 500-2,200 degreeC.

19. (1) A composite is prepared by impregnating the felt of item 10 into a resin,

(2) heat-processing a composite at 500-2,200 degreeC,

The manufacturing method of the heat insulating material containing each process.

Since the nonwoven fabric of this invention contains carbon fiber of high elongation and high elastic modulus, it is excellent in mechanical strength, it is suitable for the needle punch process, and is suitable for felting. According to the manufacturing method of the nonwoven fabric of this invention, the tensile elongation of pitch-type carbon fiber can be improved by making the oxygen addition amount with respect to an incompatible fiber into a specific range. The felt of the present invention is excellent in mechanical strength and especially in interlaminar peel strength. According to the manufacturing method of the felt of this invention, the felt which is excellent in mechanical strength and especially excellent in interlaminar peeling strength can be obtained. The heat insulating material of this invention is excellent in mechanical strength and heat insulation.

1 is a schematic diagram of a barb portion of a needle.
2 is a schematic diagram of a needle.

[Non-woven]

The present invention is a nonwoven fabric containing pitch-based carbon fibers. Pitch-based carbon fiber constituting the nonwoven fabric,

(Iii) the average fiber diameter (D1) observed with an optical microscope is larger than 2 µm and not larger than 20 µm,

(Ii) 100% of fiber diameter dispersion (S1) with respect to average fiber diameter (D1) observed with the optical microscope is 3 to 20%,

(Iii) a tensile modulus of 80 to 300 GPa, and

(Iii) The tensile elongation is 1.4 to 2.5%.

(Carbon fiber: tensile modulus and tensile elongation)

Carbon fiber has a large change in mechanical properties depending on its firing temperature. For this reason, tensile modulus and tensile elongation are largely changed by the heat history in the manufacturing process of a carbon fiber. For example, the carbon fiber which uses isotropic pitch as a raw material can fully achieve elongation exceeding 1.4% in the wide temperature range from low temperature to high temperature. However, the elastic modulus is difficult to exceed 50 GPa. On the other hand, in carbon fiber which uses mesophase pitch as a raw material, an elasticity modulus can exceed 80 kPa by setting baking temperature to 800 degreeC or more. However, in the conventional manufacturing method, elongation is smaller than 1.4%. If the firing temperature is lower than 800 ° C, the elastic modulus of 80 kPa cannot be achieved. As described above, in the prior art, it was difficult to obtain a pitch-based carbon fiber having a tensile modulus of 80 to 300 GPa and a tensile elongation in the range of 1.4 to 2.5%.

A feature of the present invention is to provide an infusible fiber in which the oxygen addition amount is 8 to 15% by weight in the infusible treatment during the production process of the pitch-based carbon fiber using mesophase pitch as a raw material, and the infused fiber is 800 to 1,800. It is to manufacture pitch-type carbon fiber which has high tensile elongation and has high elastic modulus conventionally by baking at ° C.

The tensile elasticity modulus of the pitch type carbon fiber which comprises the nonwoven fabric of this invention is 80-300 GPa, Preferably it is 100-300 GPa, More preferably, it is 180-300 GPa. The tensile elongation of the pitch type carbon fiber which comprises the nonwoven fabric of this invention is 1.4 to 2.5%, Preferably it is 1.5 to 2.4%, More preferably, it is 1.6 to 2.3%. Therefore, the pitch-based carbon fiber constituting the nonwoven fabric of the present invention preferably has a tensile modulus of 100 to 300 GPa, a tensile elongation of 1.5 to 2.4%, a tensile modulus of 180 to 300 GPa, and a tensile elongation of 1.6 to 2.3. It is more preferable that it is%.

(Carbon Fiber: Average Fiber Diameter (D1) and Fiber Diameter Dispersion (S1))

The pitch-based carbon fiber constituting the nonwoven fabric of the present invention is 100 fraction of the fiber diameter dispersion (S1) with respect to the specific average fiber diameter (D1) and the average fiber diameter (D1) in order to set the tensile modulus and the elongation in the above range. Has

The average fiber diameter D1 observed with the optical microscope of the pitch-type carbon fiber which comprises the nonwoven fabric of this invention is larger than 2 micrometers, and is 20 micrometers or less. It is preferable that an average fiber diameter is larger than 10 micrometers and 20 micrometers or less, and it is excellent in oxidation resistance and strength. More preferably, it is larger than 10 micrometers and 15 micrometers or less.

100 fraction of fiber diameter dispersion (S1) with respect to the average fiber diameter (D1) observed with the optical microscope of the pitch-type carbon fiber which comprises the nonwoven fabric of this invention is 3 to 20%, Preferably it is 5 to 15%, More preferable Preferably it is 8 to 13%.

(Tensile strength of nonwoven fabric)

The tensile strength of the nonwoven fabric of the present invention is preferably 10 N / 5 cm piece or more, and more preferably 12 N / 5 cm piece or more. If the tensile strength of a nonwoven fabric is 10 N / 5 cm piece or more, the tensile strength of the felt obtained by shaping | molding processes, such as a needle punch, will improve. This felt can be used for applications such as heat insulation and sound insulation. The tensile strength of a nonwoven fabric is the value which pulled the sample of width 5cm x length 20cm by the tensilon measuring apparatus in the longitudinal direction.

[Production method of nonwoven fabric]

The nonwoven fabric of the present invention (1) spins mesophase pitch to produce a precursor web containing a carbon fiber precursor [step (1)],

(2) infusing the precursor web in an oxidizing gas atmosphere to produce an infusible web containing carbon fibers having an oxygen addition amount of 8 to 15% by weight (step (2)), and

(3) firing the incompatible web at 800 to 1,800 ° C. [step (3)],

It can manufacture by each process. By this method, the nonwoven fabric of the present invention containing pitch-based carbon fibers having high elongation and high elastic modulus can be obtained.

Each process of this invention is demonstrated in order below.

(Step (1): Spinning)

As a raw material of pitch type carbon fiber, mesophase pitch is preferable. The mesophase rate of mesophase pitch becomes like this. Preferably it is 90% or more, More preferably, it is 95% or more, More preferably, it is 99% or more. In addition, the mesophase rate of mesophase pitch can be confirmed by observing the pitch in a molten state with a polarization microscope. As a raw material of a mesophase pitch, condensed polycyclic hydrocarbon compounds, such as naphthalene and phenanthrene, condensed heterocyclic compounds, such as petroleum pitch and coal type pitch, etc. are mentioned, for example. Among them, condensed polycyclic hydrocarbon compounds such as naphthalene and phenanthrene are preferable.

Moreover, as for the softening point of a raw material pitch, 230 degreeC or more and 340 degrees C or less are preferable. Incompatibility treatment of the carbon fiber precursor needs to be carried out at a lower temperature than the softening point. For this reason, when the softening point is lower than 230 degreeC, it is unpreferable since it needs to carry out incompatibility treatment at the low temperature which is at least less than a softening point, and consequently requires long time for incompatibility. On the other hand, when the softening point exceeds 340 ° C, the pitch tends to cause thermal decomposition, and since such a problem occurs that bubbles are generated in the yarn by the generated gas, this is not preferable. The more preferable range of a softening point is 250 degreeC or more and 320 degrees C or less, More preferably, they are 260 degreeC or more and 310 degrees C or less. In addition, the softening point of a raw material pitch can be calculated | required by a METTLER method. You may use a raw material pitch combining 2 or more types as appropriate. It is preferable that the mesophase rate of the raw material pitch to combine is at least 90%, and a softening point is 230 degreeC or more and 340 degrees C or less.

Step (1) is a step of spinning a mesophase pitch to produce a precursor web containing a carbon fiber precursor. There is no restriction | limiting in particular in a spinning method, What is called a melt spinning method is applicable. Specifically, the conventional spinning drawing method which draws the mesophase pitch discharged from the detention with a winder, the melt blow method which uses a hot air as an atomizing source, the centrifugal spinning method which draws mesophase pitch using centrifugal force, etc. are mentioned. Can be. Especially, it is preferable to use a melt blow method for reasons of control of a carbon fiber precursor form, productivity height, etc.

Hereinafter, the melt blow method will be described. In the present invention, the shape of the spinning nozzle forming the carbon fiber precursor may be any. Usually, a round shape is used, but there is no problem at all even if a nozzle of a shape such as an ellipse is used in a timely manner. As a ratio (LN / DN) of the length LN of a nozzle hole and the hole diameter DN, the range of 2-20 is preferable. When the LN / DN exceeds 20, a strong shear force is imparted to the mesophase pitch passing through the nozzle, and the radial structure is expressed on the fiber cross section. The expression of the radial structure is not preferable because cracking may occur in the fiber cross section during the firing process, and the mechanical properties may be lowered. On the other hand, when LN / DN is less than 2, a shear cannot be provided to a raw material pitch, and as a result, it becomes a carbon fiber precursor with low orientation. For this reason, even if it bakes, excellent mechanical characteristics cannot be exhibited and it is unpreferable.

In order to realize the excellent mechanical characteristics, it is necessary to give a suitable shear to the mesophase pitch. For this reason, the range (LN / DN) of the length LN of the nozzle hole and the hole diameter (DN) is preferably in the range of 2 to 20, and more preferably in the range of 3 to 12. No particular limitation is imposed on the nozzle temperature at the time of spinning, the shear rate when the mesophase pitch passes through the nozzle, the amount of air blown out of the nozzle, the temperature of the wind, and the like, and the conditions for maintaining a stable spinning state, that is, the mesophase pitch Melt viscosity in a nozzle hole should just be in the range of 1-100 Pa.s.

If the melt viscosity of the mesophase pitch passing through the nozzle is less than 1 Pa · s, the melt viscosity is too low to maintain the shape of the yarn, which is not preferable. On the other hand, when the melt viscosity of a mesophase pitch exceeds 100 Pa.s, it is unpreferable because a strong shear force is provided to a mesophase pitch, and a radial structure is formed in a fiber cross section. In order to keep the shear force applied to the mesophase pitch in an appropriate range and maintain the fibrous shape, it is necessary to control the melt viscosity of the mesophase pitch passing through the nozzle. For this reason, it is preferable to make the melt viscosity of a mesophase pitch into the range of 1-100 Pa.s, Furthermore, it is preferable to set it as the range of 3-30 Pa.s, and to set it as the range of 5-25 Pa.s. More preferred.

In this invention, the carbon fiber which comprises a nonwoven fabric is characterized by having an average fiber diameter (D1) larger than 2 micrometers and 20 micrometers or less. The control of the average fiber diameter of carbon fiber can be adjusted by changing the hole diameter of a nozzle, changing the discharge amount of the raw material pitch from a nozzle, or changing a draft ratio. The draft ratio can be changed by injecting a gas having a linear velocity of 100 to 20,000 m per minute heated at 100 to 400 ° C in the vicinity of the flash point. Although there is no restriction | limiting in particular in the gas which injects, Air is preferable from a cost performance and safety point.

The carbon fiber precursor is collected in a belt such as a wire mesh to become a precursor web. In that case, although it can adjust to arbitrary apparent weight according to a belt conveyance speed, you may laminate | stack by methods, such as a cross wrap, as needed. The apparent weight of the precursor web is preferably 150 to 1,000 g / m 2 in view of productivity and process stability.

It is preferable that the average fiber length of a carbon fiber precursor is the range of 4-25 cm. When the average fiber length of a carbon fiber precursor is less than 4 cm, since the intensity | strength of the precursor web collected by belts, such as a wire mesh, falls remarkably, it becomes difficult to laminate | stack by methods, such as a cross wrap, and it is unpreferable because it causes a fall of productivity. not. On the other hand, when it exceeds 25 cm, the precursor web becomes very bulky, and it becomes difficult to eliminate the heat of reaction generated by the reaction between the precursor web and the oxidizing gas in the incompatibility, which is the next step, and sometimes disappears. There is a problem and is undesirable. The more preferable range of the average fiber length of a carbon fiber precursor is 5-10 cm.

It is preferable to make the average fiber diameter of the carbon fiber precursor obtained by spinning to be larger than 2 micrometers, and to 20 micrometers or less. When the average fiber diameter is 2 µm or less, it is difficult to control the amount of oxygen added in the step of producing infusible fibers in which the amount of oxygen added is 8 to 15% by weight from the carbon fiber precursor. For this reason, since the quality of the carbon fiber obtained by baking cannot be stabilized and in some cases, the carbon fiber precursor is lost by the heat of incompatibility, it is not preferable. On the other hand, when an average fiber diameter exceeds 20 micrometers, in the process of manufacturing the infusible fiber whose oxygen addition amount is 8-15 weight% from a carbon fiber precursor, the infusible fiber whose oxygen addition amount exceeds 8 weight% is manufactured. It is not preferable because it requires enormous time to do so, which causes a significant decrease in productivity. The more preferable range of the average fiber diameter of a carbon fiber precursor is larger than 10 micrometers and 20 micrometers or less, More preferably, it is larger than 10 micrometers and 15 micrometers or less.

Moreover, it is preferable that 100 fraction of fiber diameter dispersion (S1) with respect to the average fiber diameter of a carbon fiber precursor is 3 to 20% of range. The CV value is an index of the deviation of the fiber diameter, and the smaller the value, the higher the process stability and the smaller the deviation. However, when it is going to make what the real CV value is smaller than 3%, it is necessary to control the nonuniformity of the amount of resin discharged | emitted from each capillary of a spinneret as much as possible. For this reason, a spinneret is made small and, as a result, a significant fall in productivity due to a decrease in the number of capillaries is caused. On the other hand, when CV value is larger than 20%, in the process of manufacturing the infusible fiber whose oxygen addition amount is 7-15 weight% from a carbon fiber precursor, control of an oxygen addition amount is difficult and consequently the pitch system obtained by baking It is not preferable because the quality of the carbon fiber cannot be stabilized. The range with more preferable CV value is 8 to 15%.

(Step (2): Incompatibility)

Step (2) is a step of making the precursor web infusible under an oxidizing gas atmosphere to produce an infusible web containing carbon fibers having an oxygen addition amount of 8 to 15% by weight.

The present invention is characterized in that the amount of oxygen added to the incompatible fiber obtained in the step (2) is 8 to 15% by weight. When the oxygen addition amount of the incompatible fiber is less than 8% by weight, the tensile elongation of the carbon fiber obtained by firing in the step (3) cannot exceed 1.4%. On the other hand, when the amount of oxygen added is more than 15% by weight, a significant decrease in the excellent elastic modulus, which is characteristic of the pitch-based carbon fibers using mesophase pitch, is not preferable. The range of preferable oxygen addition amount for obtaining the outstanding tensile elongation and elastic modulus is 8 to 13 weight%, Furthermore, 9 to 12 weight% is especially preferable.

The incompatibility of the carbon fiber precursor is carried out in an oxidizing gas atmosphere. The oxidizing gas in the present invention refers to a gas or a mixed gas of air and a gas from which electrons can be extracted from the carbon fiber precursor. As a gas which can extract an electron from a carbon fiber precursor, ozone, iodine, bromine, oxygen, etc. can be illustrated. However, in consideration of safety, convenience, and cost performance, it is particularly preferable to perform incompatibility of the carbon fiber precursor in air.

Although the incompatibility of a carbon fiber precursor can be processed by either batch processing or continuous processing, continuous processing is preferable in consideration of productivity. The temperature of incompatibility becomes like this. Preferably it is 150-350 degreeC, More preferably, it is 160-340 degreeC. In a batch process, 1-10 degreeC / min of a temperature increase rate is used preferably. The more preferable range of a temperature increase rate is 3-9 degreeC / min in consideration of productivity and process stability. In the case of continuous processing, a temperature increase rate can be achieved by passing a plurality of reaction chambers set at arbitrary temperatures sequentially. When passing a carbon fiber precursor through several reaction chamber one by one, you may use a conveyance conveyor etc. The amount of oxygen added to the incompatible fiber is highly dependent on the temperature in the furnace and the residence time in the furnace. In continuous processing, it is preferable to make the oxygen addition amount of a pitch system infusible chamber into 8-15 weight% by controlling the speed of a conveyance conveyor, the temperature of each reaction chamber, and controlling the residence time of each reaction chamber. As a speed | rate of a conveyance conveyor, although it changes also with the number and size of reaction chambers, 0.1-1.5 m / min is preferable.

(Step (3): Firing)

Step (3) is a step of baking the incompatible web at 800 to 1,800 ° C. to obtain a nonwoven fabric.

The incompatible web is fired in a vacuum or in a non-oxidizing atmosphere using an inert gas such as nitrogen, argon or krypton to form a nonwoven fabric. In consideration of cost, the baking treatment is preferably performed under atmospheric pressure and under a nitrogen atmosphere. In addition, although either of batch processing and continuous processing can be processed, continuous processing is preferable in consideration of productivity.

In the method of this invention, the fiber length retention (%) represented by following formula (I) in a baking process can be 90% or more in the baking process by making the oxygen addition amount of the incompatible fiber of a process (2) into 8-15 weight%. have.

Fiber Length Retention Rate = 100 × L ¹ / L ⁰ (Ⅰ)

L ⁰ : fiber length before firing

L ¹ : fiber length after firing

The more preferable range of fiber length retention is 95% or more. When the fiber length retention exceeds 90%, the reason why the tensile elongation of the pitch-based carbon fibers becomes higher than before is not well known. It is known that carbonization of mesophase pitch is via a liquid phase. In the method of the present invention, since it is necessary to add a higher concentration of oxygen to the carbon fiber precursor than in the prior art to make incompatible fibers, oxygen crosslinking of the carbon fiber precursor proceeds to infer whether the change from liquid carbonization to solid carbonization is the cause. have.

[Short fiber]

In order to make pitch-type carbon fiber into a desired fiber length, you may process cutting | disconnection, crushing, crushing, etc. to the obtained nonwoven fabric. In addition, depending on the case, you may perform a classification process. The treatment method is selected according to the desired fiber length, and cutters such as guillotine type, uniaxial, biaxial and multiaxial rotary are preferably used. For crushing and pulverizing, hammer, pin, ball, bead and rod type using impact action, high speed rotation using collision between particles, roll type using compression and tear action, cone type and screw type etc. It is preferably used.

In order to obtain a desired fiber length, you may comprise cutting | disconnection, crushing, and grinding | pulverization with multiple types of condensers. The treatment atmosphere may be either wet or dry. A classification apparatus such as a vibrating sieve, centrifugal separation, inertial force, filtration or the like is preferably used for the classification treatment. The desired fiber length can be obtained not only by selecting the model but also by controlling the rotation speed of the rotor and the rotary blade, the supply amount, the clearance between the blades, the residence time in the system, and the like. In addition, when using a classification process, desired fiber length can also be obtained by adjusting the hole diameter of a sieve net, etc. These treatments result in pitch-based short carbon fibers.

Pitch-based short carbon fibers obtained by nonwoven fabric or crushing containing pitch-based carbon fibers obtained in the above description are further heated to 2,000 to 3,500 ° C to graphitize and non-woven fabric or pitch system containing final pitch-based graphitized fibers. It is good also as graphitized short fiber. Graphitization is carried out in an Acheson furnace, an electric furnace, or the like, and is performed in a vacuum or under a non-oxidizing atmosphere using an inert gas such as nitrogen, argon, krypton, or the like.

[felt]

Since the nonwoven fabric of the present invention is composed of pitch-based carbon fibers having high elongation and elastic modulus, it is suitable for the needle punch treatment, and the felt can be preferably obtained from the nonwoven fabric of the present invention. The present invention includes a felt obtained by needle punching the nonwoven fabric.

The interlaminar peel strength in the thickness direction of the felt of the present invention is preferably 0.25 N / 5 cm piece or more, and more preferably 0.35 N / 5 cm piece. If the interlaminar peeling strength is smaller than 0.25 N / 5 cm piece, the interlacing between the laminations subjected to the cross lap is not sufficient, causing interlaminar peeling at the time of processing, resulting in poor handling, and also causing the occurrence of uneven physical properties. Here, an interlayer peeling strength shows the entanglement intensity | strength of the thickness direction of a felt. The sheath is inserted into the blade parallel to the layer direction at the intermediate position in the thickness direction of the felt, and both ends thereof are obtained from the maximum strength when the tensile tester is pulled at a speed of 100 mm / min.

It is preferable that the average fiber diameter of the carbon fiber which comprises the felt of this invention observed with the optical microscope is larger than 2 micrometers, and is 20 micrometers or less. When an average fiber diameter is 2 micrometers or less, since the space | gap part is subdivided, the resin impregnation property at the time of shaping | molding process may not be favorable. On the contrary, when the average fiber diameter exceeds 20 µm, the thermal conductivity increases in the high temperature region in which the dominance of the radiant heat becomes stronger because the voids become large, so that the heat insulating property may decrease. The more preferable range of average fiber diameter is especially larger than 10 micrometers and 20 micrometers or less, More preferably, it is larger than 10 micrometers and 15 micrometers or less from the purpose of oxidation resistance and a raise of strength.

It is preferable that the apparent weight of the felt of this invention is 250-1,000 g / m <2>. Although apparent weight can be adjusted according to a use, 250-1,000 g / m <2> is optimal for stable continuous production. If the apparent weight is less than 250 g / m 2, since the pitch-based carbon fiber web is thin, web breakage and wrinkles may occur due to the felting process. On the contrary, when the apparent weight is larger than 1,000 g / m 2, the thickness is large, so that the heat dissipation of the pitch-based infusible fibrous web is not performed smoothly at the time of incompatibilization treatment, and fusion between fibers may occur. The more preferable range of apparent weight is 400-700 g / m <2>.

Therefore, it is preferable that the average fiber diameter of the carbon fiber which comprises the felt of this invention is larger than 10 micrometers, and is 20 micrometers or less, and apparent weight is 250-1,000 g / m <2>. This invention contains the graphitized felt obtained by heat-processing the said felt further at 2,000-3,500 degreeC.

It is preferable that the graphitized felt of this invention is 20 micrometers or less in average fiber diameter of graphitized fiber larger than 2 micrometers, and apparent weight is 250-1,000 g / m <2>. Since the graphitized felt is produced from the above-described felt, the apparent weight is a weight decrease from the original weight of the original felt by the graphitization treatment. The apparent weight of the graphitized felt can be appropriately adjusted according to the selection of the apparent weight of the original felt.

If the apparent weight of the original felt is less than 250 g / m 2, the web may be broken or wrinkled due to the felting process because the pitch-based carbon fiber web is thin. On the contrary, when the apparent weight is larger than 1,000 g / m 2, the thickness becomes large, so that the heat dissipation of the pitch-based incompatible fiber web is not performed smoothly at the time of incompatibility treatment, and fusion between fibers may occur. The more preferable range of apparent weight is 400-700 g / m <2>.

Moreover, it is preferable that the weight reduction at the time of raising the graphitized felt of this invention at 3 degree-C / min in air is less than 10 wt% of an initial weight. If the weight loss is 10 wt% or more of the initial weight, the oxidation resistance is remarkably lowered, which is not preferable because the characteristics when used as a heat insulating material cannot be sufficiently satisfied. As weight reduction in air when heated up at 3 degree-C / min, 8 weight% or less, Furthermore, 5 weight% or less is preferable. In addition, the weight reduction at the time of heating up at 3 degree-C / min in air can be measured, for example with a thermodifferential weight analyzer.

The graphitized felt of the present invention has a lower graphitization property than the graphitized felt produced from the felt of the prior art. For this reason, thermal conductivity also becomes low and shows the outstanding heat insulation characteristic, for example, when using as a heat insulating material. The reason for the low graphitization of the graphitized felt of the present invention is not well understood, but in the method of the present invention, it is necessary to add a higher concentration of oxygen to the carbon fiber precursor than in the prior art to make incompatible fibers, and thus the oxygen of the carbon fiber precursor It is speculated that crosslinking progresses and the change from liquid carbonization to solid carbonization is not the cause.

[Method of Manufacturing Felt]

The present invention (1) spinning a mesophase pitch to produce a precursor web containing a carbon fiber precursor [step (1)],

(2) The precursor web was infusified under an oxidizing gas atmosphere to prepare an infusible web containing infusible fibers having an oxygen addition amount of 8 to 15% by weight (step (2)),

(3) firing the incompatible web at 800 to 1,800 ° C. to produce a nonwoven fabric [step (3)], and

(4) needle punching the nonwoven fabric [Step (4)],

The manufacturing method of the felt containing each process is included.

Process (1)-(3) is the same as the manufacturing method of the nonwoven fabric mentioned above. However, it is preferable to optimize the conveyance speed ratio in process (2) and process (3) with respect to heat shrink. Conventionally, it has been found that productivity is increased by collecting and cross-lapping pitch-based carbon fibers spun by the melt blow method, but it is difficult to entangle the cross-lapping stacks. Since it is strongly entangled at the time of a later collection, even if it laminate | stacks felting processes, such as a needle punch process, it originates in that carbon fiber is hard to move to a thickness direction. In addition, since carbon fiber is hard and soft, fiber breakage only occurs by simply increasing the number of punches, but the strength decreases and the yield decreases. Therefore, in order to entangle without increasing the number of punches, it is desirable to optimize the shape of the needle.

In addition, since heat shrinkage occurs when calcining the incompatible web to form a nonwoven fabric, the carbon fiber is pulled in the web because the incompatible web is stretched at the time of firing when produced in a continuous process. Furthermore, the web is often torn. If the carbon fiber is in the pulled state in the web, it is difficult to perform a felting process such as a needle punch, which causes fiber breakage, and the interlaminar peel strength is lowered. Therefore, measures for mitigating heat shrinkage during the firing process are necessary, and therefore, it is preferable to optimize the conveyance speed ratio in the step (2) (incompatibility) and the step (3) (firing) with respect to the heat shrinkage. That is, it is preferable to make ratio (V1 / V2) of the conveyance speed V1 of the web of a process (2), and the conveyance speed V2 of the web of a process (3) to 1.01-1.10.

Step (4) is a step of needle punching the nonwoven fabric. The punch number of the needle punches is preferably 1 to 200 times / cm 2, more preferably 15 to 100 times / cm 2. The barb depth of the needle is preferably 0.15 mm or more, more preferably 0.2 to 0.4 mm. Therefore, in the step (4), it is preferable that the nonwoven fabric is needle punched with a punch number of 15 to 100 times / cm 2 with a needle having a barb depth of 0.15 mm or more.

If the barb depth is smaller than 0.15 mm, there are few entanglements in the range of punch number 15 to 100 times / cm 2, and sufficient interlaminar peeling strength cannot be obtained. If the punch number is smaller than 15 times / cm 2, even if the barb depth is 0.15 mm or more, there is little entanglement and sufficient interlaminar peel strength cannot be obtained. On the contrary, when larger than 100 times / cm <2>, a lot of fiber breakages will occur, and strength will fall and production rate will fall. The more preferable range of barb depth is 0.20 mm or more, and the more preferable range of punch number is 15-50 times / cm <2>.

In addition, barb depth is the depth of the sheath called barb of a needle, as shown in FIG. Bobbu also has a kick called a kick-up.

The kick-up height, the number of barbs, the adjacent barb spacing, and the needle depth of the needle are appropriately selected in accordance with the apparent weight, thickness, and the like of the felted nonwoven fabric. Kick-up height can be suitably selected from the range of 0-0.15 mm. If the kick-up height is larger than 0.15 mm, fiber breakage may occur a lot, resulting in a decrease in strength and a decrease in production rate. In addition, the number of barbs can be suitably selected from the range of 3-18 pieces. When the number of barbs is less than three, there are few entanglements and sufficient interlaminar peeling strength may not be obtained. On the contrary, when there are more than 18 pieces, a lot of fiber breakages may occur, and strength may fall and production rate may fall. Adjacent barb spacing can be suitably selected from the range of 0.3-3 mm. In addition, the adjoining barb spacing in this invention means what included adjoining between two rows of blades. When the adjacent barb spacing is smaller than 0.3 mm, a lot of fiber breakage may occur and a strength fall and a fall of a production rate may occur. On the contrary, when larger than 3 mm, there may be few entanglements and sufficient interlaminar peeling strength may not be obtained. Needle depth can be suitably selected from the range of 0-20 mm. The depth of the needle indicates how deeply the needle is pierced with respect to the felt, and is represented by the distance of the barb (commonly referred to as the first barb) at the shortest distance from the bed plate and the needle tip when needle punched. If the needle depth is smaller than 0 mm, there may be less entanglements and sufficient interlaminar peeling strength may not be obtained. On the contrary, when it is larger than 20 mm, a lot of fiber breakages may occur, and strength may fall and a yield may fall.

1 and 2 schematically show the kick-up height, the needle depth, and the adjacent barb spacing.

The carbon fibers constituting the nonwoven fabric of the present invention have a high elongation and a high modulus of elasticity, and thus are suitable for the needle punch treatment. By needle punching, the bulk density of the felt is preferably 0.01 to 0.5 g / cm 3, and more preferably 0.03 to 0.3 g / cm 3. Although the thickness of a felt should just be selected according to a use, it is not specifically limited, For example, it is 1-100 mm, Preferably it is about 5-50 mm. The felt of this invention can be used suitably for a heat insulating material, a soundproofing material, etc.

[Composite]

The present invention includes a composite obtained by impregnating a resin in the felt. The resin is preferably a thermosetting resin. The composite can be obtained by impregnating a thermosetting resin in a felt, and usually thermoforming after thermoforming.

Phenolic resin, epoxy, acrylic, urethane, silicone, imide, thermosetting modified PPE, thermosetting PPE, polybutadiene rubber and its copolymer, acrylic rubber and its copolymer, silicone type as thermosetting resin Rubber, its copolymer, natural rubber, etc. are mentioned, You may use individually by 1 type from these, and may use it in combination of 2 or more types as appropriate. The weight of the resin is preferably 50 to 1,000 parts by weight, more preferably 100 to 700 parts by weight based on 100 parts by weight of the felt. You may use the said graphitized felt as said felt.

[insulator]

The present invention includes a heat insulating material obtained by heat-treating the composite at 500 to 2,200 ° C. That is, the heat insulating material of the present invention (1) to impregnate the felt with a resin to produce a composite,

(2) The composite can be produced by heat treatment, that is, carbonization, at 500 to 2,200 ° C. As for the temperature of the heat processing at this time, ie, the carbonization process, 800 degreeC or more and 2,000 degrees C or less are preferable.

The average fiber diameter of the carbon fiber constituted as described above should be in the range of larger than 2 µm and 20 µm or less, especially when the average fiber diameter is larger than 10 µm and 20 µm or less, more preferably larger than 10 µm and 15 µm or less. It is excellent in oxidation resistance and strength, hardly oxidatively deteriorates even at high temperatures, is excellent in durability, and is preferably used as a heat insulating material for high temperature treatment furnaces.

The heat insulating material contains 50-1,000 weight part of carbides with respect to 100 weight part of pitch type carbon fiber felts. Carbide here means the component obtained by carbonizing a thermosetting resin when heat-processing the composite body mentioned above. When the carbide is less than 50 parts by weight, it means that the voids of the felt are small, that is, the bulk density of the felt becomes high, resulting in deterioration of thermal insulation. On the contrary, in the case where the carbide exceeds 1,000 parts by weight, most of the heat insulating material is carbide derived from a thermosetting resin, and there are less felts which can expect oxidation resistance, which is not preferable. Preferably it is 100-700 weight part carbides with respect to 100 weight part felt. The weight ratio of carbide and felt can be calculated from the weight of carbide by subtracting the weight of the pitch-based carbon fiber felt measured in advance from the weight of the obtained composite.

In general, since the heat insulating material is used under the harsh conditions of high temperature, high durability is required. The felt made of the pitch-based carbon fiber of the present invention is hardly oxidatively deteriorated even at a high temperature, and hardly oxidatively deteriorated even in the state of being made into a composite material. For this reason, since the heat insulating material of this invention is excellent in durability, it can be used also for the furnace heat-processed.

Example

Hereinafter, although an Example demonstrates this invention further more concretely, this invention is not limited at all by this.

In Examples 1-13 and Comparative Examples 1-5, each physical property was measured with the following method.

(1) average fiber diameter (D1) and fiber diameter dispersion (S1) of carbon fiber

The average fiber diameter (D1) measured 60 fiber diameters of carbon fiber using the scale under an optical microscope, and calculated | required from the average value. Moreover, CV value was obtained with the obtained average fiber diameter (D1) and fiber diameter dispersion (S1). ) Was determined by the following formula.

CV = S1 / D1 × 100

이고, X 는 관측값, n 은 관측수이다.here,

Where X is the observation and n is the number of observations.

(2) average fiber length of carbon fiber precursor

The average fiber length of a carbon fiber precursor was calculated | required by collecting the bundle of a carbon fiber precursor in three fiber collection brushes formed in the position of 30 cm under detention, and measuring and averaging the length of those bundles.

(3) fiber length retention rate

From the value of a fiber length (L ¹⁾ and fiber length (L ⁰⁾ before firing of the carbon fibers fired at 800 ℃, the fiber length retention was obtained from the following formula (Ⅰ).

Fiber Length Retention Rate = 100 × L ¹ / L ⁰ (Ⅰ)

L ⁰ : fiber length before firing

L ¹ : fiber length after firing

Further, the fiber length of the carbon fiber (L ¹⁾ is pulled out of 10 from a plastic non-woven fabric at 800 ℃, it was evaluated by averaging by measuring its length. In addition, the fiber length (L ⁰ ) before baking was pulled out from the infusible web, and it evaluated by measuring and averaging the length.

(4) Oxygen addition amount of incompatible fiber

The oxygen addition amount of the incompatible fiber was measured by a CHNS-O analyzer (FLASH EA 1112 Series manufactured by Thermo ELECTRON CORPORATION).

(5) tensile elongation of carbon fiber, tensile modulus of elasticity, tensile strength of nonwoven fabric

Tensile elongation and tensile modulus of carbon fiber was measured by pulling the yarns of 120 carbon fibers and measuring the fiber diameters, and then measuring the mechanical strength of 120 carbon fibers using a tensilon measuring device (ORI ENTEC RTC-1150A). It determined by obtaining the total number average value of elastic modulus.

(6) tensile strength of nonwoven fabric

A sample of 5 cm in width x 20 cm in length was taken out from a total of six points in each of the two left, middle, and right sides in the width direction from the nonwoven fabric, and pulled in the length direction at a speed of 100 mm / min with a tensile tester, and the strength thereof. It determined by calculating the average value of.

(7) interlayer peel strength of felt

A sample having a width of 5 cm x 10 cm in length was taken out from the felt in total of six points each of the two left, middle, and right sides in the width direction, and the sheath was cut with the blade parallel to the layer direction at the intermediate position of the thickness direction, Both ends were calculated | required from the average value of the maximum strength at the time of tension | tensile_strength at the speed | rate of 100 mm / min by the tension tester.

(8) the apparent weight of the felt

The apparent weight was computed by taking out the sample of A4 size from the total of 6 points of 2 points of each of the left, middle, and right in the width direction from the felt, and measuring the weight.

(9) tensile strength of insulation

It measured by the large-scale characteristic test apparatus (SS-207-5P by Toyo Baldwin).

(10) Cross section of composite material with phenolic resin

The pores were confirmed by observing at a magnification of 1,000 times with a scanning electron microscope.

(11) thermal conductivity of insulation

It was calculated | required by the probe method using Kyoto Electronics Co., Ltd. QTM-500.

(12) weight ratio of carbide to carbon fiber felt

The weight of the carbide was calculated by subtracting the weight of the carbon fiber felt measured in advance from the weight of the obtained composite.

(13) Oxidation Resistance of Graphitized Felt

Using a differential thermogravimetric analyzer (Tig8120, manufactured by Rigaku Electric Co., Ltd.), the temperature was raised from room temperature to 3 ° C / min in air to evaluate the amount of weight reduction at 700 ° C.

Example 1

(radiation)

Mesophase pitch of 100% of mesophase rate consisting of aromatic hydrocarbons and a softening temperature of 278 ° C was used every minute from a slit next to the capillary at 335 ° C, using a cap including a 0.2 mm diameter diameter and a 2 mm length capillary. Air at 339 ° C. was injected at 8,000 m to pull the molten mesophase pitch to prepare a precursor web containing carbon with an average diameter of 13.0 μm. The carbon fiber precursor immediately below the mold was collected with a wire brush, and the average fiber length was confirmed, and found to be 8.4 cm.

(Incompatibility)

Next, the precursor web was heated for 30 minutes from 200 ° C to 340 ° C in an air atmosphere to prepare an infusible web made of infusible fibers. The oxygen addition amount of the incompatible fiber was 10.9% by weight. In addition, the average fiber length of the incompatible fiber was 8.5 cm.

(Firing)

Subsequently, the nonwoven fabric which consists of carbon fiber was manufactured by baking at 800 degreeC in nitrogen atmosphere continuously. At this time, ratio (V1 / V2) of the conveyance speed V1 of the web at the time of incompatibilization process, and the conveyance speed V2 of the web at the time of baking process was 1.03. The average fiber diameter of the obtained carbon fiber was 12.1 micrometers, and the CV value of the fiber diameter was 10.2%. In addition, the average fiber length of carbon fiber was 8.1 cm, and fiber length retention was 95%. Moreover, when the tensile strength of the nonwoven fabric which consists of carbon fibers was measured, it was 15.5 N / 5 cm piece.

In addition, the incompatible web was calcined at 1,500 ° C. over an hour from room temperature in an argon gas atmosphere to obtain a nonwoven fabric made of carbon fibers. As a result of evaluating the mechanical properties of this carbon fiber, the tensile elongation was 1.61%, the tensile strength was 3.0 kPa, and the tensile elasticity modulus was 240 kPa.

Example 2 (Felt)

The nonwoven fabric made of the carbon fiber obtained in Example 1 was needled at a punch count of 20 times / cm 2 and a needle depth of 10 mm by using a needle having a kick-up height of 0.05 mm, a number of barbs of 9, an adjacent barb spacing of 3 mm, and a barb depth of 0.25 mm. Punched to obtain a felt. The interlayer peel strength of the obtained felt was 0.45 N / 5 cm piece, the average fiber diameter was 12.1 micrometers, and the apparent weight was 445 g / m <2>.

Example 3 (Composite-Insulation)

The felt prepared in Example 2 was immersed in a phenol resin (manufactured by Gun-A Chemical Co., Ltd., PL-2211, viscosity 0.1 Pa.s), compressed by a roll press to squeeze excess phenol resin, and then molded at 250 ° C. To a composite material, and calcined at 800 ° C. Furthermore, it heat-processed at 2,000 degreeC and obtained the carbon fiber containing heat insulating material. 400 parts by weight of carbide was contained based on 100 parts by weight of carbon fiber felt. As a result of observing the cross section of the fired body, no void was observed. The tensile strength of the heat insulating material was 0.74 MPa, and the thermal conductivity was 0.048 W / mK. The tensile strength after processing for 24 hours at 2,000 degreeC and 20 ppm of oxygen concentration was 0.68 Mpa.

Example 4 (graphitized felt)

The felt prepared in Example 2 was calcined at 2,000 ° C. over 3 hours from room temperature under an argon gas atmosphere to obtain a graphitized felt. The apparent weight was 438 g / m 2 and the average fiber diameter of the single yarn constituting the graphitized felt was 11.3 μm. In addition, the weight reduction in 700 degreeC when the graphitized felt was heated at 3 degree-C / min from room temperature to 700 degreeC in air was 4.8 wt% of the initial weight.

Example 5 (graphitizing felt-heat insulating material)

The graphitized felt prepared in Example 4 was immersed in a phenolic resin (manufactured by Gunei Chemical Co., Ltd., PL-2211, viscosity 0.1 Pa.s), compressed by a roll press to squeeze the excess phenolic resin, and then 250 ° C. It shape | molded at and made into a composite, and it baked at 800 degreeC. Furthermore, it heat-processed at 2,000 degreeC, and obtained the graphitizing fiber containing heat insulating material. Carbide was contained 405 weight part with respect to 100 weight part of graphitized fiber felt. As a result of observing the cross section of the fired body, no void was observed. The tensile strength of the heat insulating material was 1.23 MPa, and the thermal conductivity was 0.078 W / m * K. The tensile strength after processing for 24 hours at 2,000 degreeC and 20 ppm of oxygen concentration was 1.18 Mpa.

Example 6

(radiation)

Mesophase pitch of 100% of mesophase rate and aromatic temperature of 278 degreeC made from aromatic hydrocarbon was used every minute from the slit by the capillary using the detention which consists of a capillary of 0.2 mm diameter and 2 mm in length at 331 degreeC. 336 ° C. air was blown at 8,000 m to pull the molten mesophase pitch to produce a precursor web with an average diameter of 11.0 μm. It was 15.3 cm when the carbon fiber precursor immediately below a metal mold | die was collected with the wire brush, and the average fiber length was confirmed.

(Incompatibility)

Next, the precursor web was heated up for 30 minutes from 200 degreeC to 340 degreeC in air atmosphere, and the infusible web which consists of infusible fibers was obtained. The oxygen addition amount of the incompatible fiber was 11.8 wt%. In addition, the average fiber length of the incompatible fiber was 15.2 cm.

(Firing)

Subsequently, the nonwoven fabric which consists of carbon fiber was manufactured by baking at 800 degreeC in nitrogen atmosphere continuously. Under the present circumstances, ratio (V1 / V2) of the conveyance speed V1 of the web at the time of incompatibilization process, and the conveyance speed V2 of the web at the time of baking process was 1.02. The average fiber diameter of carbon fiber was 10.3 micrometers, and the CV value of fiber diameter was 8.2%. Moreover, the average fiber length of carbon fiber was 14.2 cm, and fiber length retention rate was 93%. Moreover, when the tensile strength of the nonwoven fabric which consists of carbon fiber was measured, it was 14.6 N / 5 cm piece.

Furthermore, the obtained incompatible web was baked at 1,500 degreeC over 1 hour from room temperature in argon gas atmosphere, and the nonwoven fabric which consists of carbon fibers was obtained. As a result of evaluating the mechanical properties of this carbon fiber, the tensile elongation was 1.55%, the tensile strength was 3.1 GPa, and the tensile modulus was 235 GPa.

Example 7 (Felt)

The nonwoven fabric made of the carbon fiber obtained in Example 6 was needled at 25 punches / cm 2 and needle depth 10 mm using a needle having a kick-up height of 0.04 mm, 9 barbs, 3 mm adjacent bar spacing, and 0.20 mm barb depth. Punched to obtain a felt. The interlayer peel strength of the obtained felt was 0.48 N / 5 cm piece, the average fiber diameter was 10.5 micrometers, and the apparent weight was 390 g / m <2>.

Example 8 (composite-insulation)

The felt prepared in Example 7 was immersed in a phenolic resin (manufactured by Gun-A Chemical Co., Ltd., PL-2211, viscosity 0.1 Pa.s), compressed with a roll press to squeeze the excess phenolic resin, and then molded at 250 ° C. To a composite material, and calcined at 800 ° C. Furthermore, it heat-processed at 2,000 degreeC and obtained the carbon fiber containing heat insulating material. 400 parts by weight of carbide was contained per 100 parts by weight of felt. As a result of observing the cross section of the fired body, no void was observed. The tensile strength of the heat insulating material was 0.79 MPa, and the thermal conductivity was 0.049 W / mK. The tensile strength after processing for 24 hours at 2,000 degreeC and 20 ppm of oxygen concentration was 0.76 Mpa.

Example 9 (graphitized felt)

The felt prepared in Example 7 was calcined at 2,500 ° C. over 3 hours from room temperature under an argon gas atmosphere to obtain a graphitized felt. The apparent weight was 385 g / m 2, and the average fiber diameter of the single yarn constituting the graphitized felt was 9.8 μm. In addition, the weight reduction in 700 degreeC when the graphitized felt was heated up at 3 degree-C / min from room temperature to 700 degreeC in air was 3.8 wt% of the initial weight.

Example 10

(radiation)

Mesophase pitch of 100% of mesophase rate and aromatic temperature of 278 degreeC which consists of aromatic hydrocarbons is used every minute from the slit of a capillary by using the detention which consists of a capillary of 0.2 mm diameter and 2 mm in length at 336 degreeC. Air at 339 ° C. was injected at 5,000 m to pull the molten mesophase pitch to prepare a precursor web composed of a carbon fiber precursor having an average diameter of 15.1 μm. It was 10.4 cm when the carbon fiber precursor immediately below a metal mold | die was collected with the wire brush, and the average fiber length was confirmed.

(Incompatibility)

Next, the precursor web was heated up for 30 minutes from 200 degreeC to 340 degreeC in air atmosphere, and the infusible web which consists of infusible fibers was obtained. The oxygen addition amount of the incompatible fiber was 8.4% by weight. In addition, the average fiber length of the incompatible fiber was 10.4 cm.

(Firing)

Subsequently, the nonwoven fabric which consists of carbon fiber was manufactured by baking at 800 degreeC in nitrogen atmosphere continuously. At this time, ratio (V1 / V2) of the conveyance speed V1 of the web at the time of incompatibilization process, and the conveyance speed V2 of the web at the time of baking process was 1.04. The average fiber diameter of carbon fiber was 14.3 micrometers, and the CV value of fiber diameter was 10.5%. Moreover, the average fiber length of carbon fiber was 9.5 cm, and the fiber length retention rate was 91%. Moreover, when the tensile strength of the nonwoven fabric which consists of carbon fibers was measured, it was 15.6 N / 5 cm piece. Furthermore, the nonwoven fabric which consists of incompatible fiber was baked at 1,500 degreeC over 1 hour from room temperature in argon gas atmosphere, and the nonwoven fabric which consists of carbon fiber was obtained. As a result of evaluating the mechanical properties of this carbon fiber, the tensile elongation was 1.48%, the tensile strength was 2.6 GPa, and the tensile modulus was 253 GPa.

Example 11 (Felt)

The nonwoven fabric made of the carbon fiber obtained in Example 10 was needle with a punch count of 30 times / cm 2 and a needle depth of 10 mm using a needle having a kick-up height of 0.05 mm, a number of barbs of 9, an adjacent barb spacing of 3 mm, and a barb depth of 0.30 mm. Punched to obtain a felt. The interlayer peel strength of the obtained felt was 0.39 N / 5 cm piece, the average fiber diameter was 14.3 micrometers, and the apparent weight was 460 g / m <2>.

Example 12 (Composite-Insulation)

The felt prepared in Example 11 was immersed in a phenol resin (manufactured by Gun-A Chemical Co., Ltd., PL-4222, viscosity 0.5 Pa · s), compressed by a roll press to squeeze excess phenol resin, and then molded at 250 ° C. To a composite material, and calcined at 800 ° C. Furthermore, it heat-processed at 2,000 degreeC and obtained the carbon fiber containing heat insulating material. 400 parts by weight of carbide was contained based on 100 parts by weight of carbon fiber felt. As a result of observing the cross section of the fired body, no void was observed. The tensile strength of the heat insulating material was 0.83 MPa, and the thermal conductivity was 0.049 W / m * K. The tensile strength after processing for 24 hours at 2,000 degreeC and 20 ppm of oxygen concentrations was 0.78 Mpa.

Example 13 (Graphite Felt)

The felt prepared in Example 11 was calcined at 3,000 ° C. over 3 hours from room temperature under an argon gas atmosphere to obtain a graphitized felt. The apparent weight was 452 g / m 2, and the average fiber diameter of the single yarn constituting the graphitized felt was 13.8 μm. In addition, the weight reduction in 700 degreeC when the graphitized felt was heated up at 3 degree-C / min from room temperature to 700 degreeC in air was 3.1 wt% of the initial weight.

Comparative Example 1

(radiation)

Mesophase pitch of 100% of mesophase rate consisting of aromatic hydrocarbons and a softening temperature of 278 ° C was used every minute from a slit next to the capillary at 335 ° C, using a cap including a 0.2 mm diameter diameter and a 2 mm length capillary. Air at 339 ° C. was injected at 8,000 m to draw a molten mesophase pitch to prepare a precursor web composed of a carbon fiber precursor having an average diameter of 13.0 μm. The carbon fiber precursor immediately below the mold was collected with a wire brush, and the average fiber length was confirmed, and found to be 8.4 cm.

(Incompatibility)

Next, the precursor web was heated up for 30 minutes from 200 degreeC to 290 degreeC in air atmosphere, and the infusible web which consists of infusible carbon fiber was obtained. The amount of oxygen added to the incompatible carbon fiber was 6.5% by weight. In addition, the average fiber length of the incompatible fiber was 8.5 cm.

(Firing)

Subsequently, the ratio (V1 / V2) of the conveyance speed V1 of the web at the time of incompatibility treatment and the conveyance speed V2 of the web at the time of baking treatment was set to 1.00, and it was continuously baked at 800 degreeC in nitrogen atmosphere, and carbon fiber Although it was intended to obtain a nonwoven fabric consisting of, the cutting of the nonwoven fabric made of carbon fiber was confirmed by shrinkage of the web. The average fiber diameter of carbon fiber was 12.1 micrometers, and the CV value of fiber diameter was 10.2%. Moreover, the average fiber length of pitch carbon fiber was 7.3 cm, and the fiber length retention was 86%. Moreover, it was 6.7 N / 5 cm piece as a result of measuring the tensile strength of the nonwoven fabric which consists of pitch type carbon fiber.

Furthermore, the obtained incompatible web was baked at 1,500 degreeC over 1 hour from room temperature in argon gas atmosphere, and the nonwoven fabric which consists of pitch type carbon fiber was obtained. As a result of evaluating the mechanical characteristics of this pitch type carbon fiber, the tensile elongation was 1.2%, the tensile strength was 1.7 kPa, and the tensile elasticity modulus was 216 kPa.

Comparative Example 2 (Felt)

The nonwoven fabric made of the carbon fiber obtained in Comparative Example 1 was needled at a punch count of 20 times / cm 2 and a needle depth of 10 mm using a needle having a kick-up height of 0.05 mm, a number of barbs of 9, an adjacent barb spacing of 3 mm, and a barb depth of 0.25 mm. Punched to obtain a felt. The interlayer peel strength of the obtained felt was 0.15 N / 5 cm piece, the average fiber diameter was 12.1 micrometers, and the apparent weight was 218 g / m <2>. In order to manufacture a heat insulating material, it attempted to immerse the obtained felt in phenol resin (manufactured by Group A Chemical Co., Ltd., PL-4222, viscosity 0.5 Pa.s), but fracture occurred in the felt because of lack of strength.

Comparative Example 3

(radiation)

Mesophase pitch of 100% of mesophase rate which consists of aromatic hydrocarbons, and softening temperature of 278 degreeC is used every minute from the slit by the capillary using the detention which consists of a capillary of 0.2 mm diameter and 2 mm in length at 328 degreeC. 335 ° C. air was blown at 3,000 m to pull the molten mesophase pitch to prepare a precursor web composed of a carbon fiber precursor having an average diameter of 21.5 μm. It was 30.4 cm when the carbon fiber precursor just under the cap was collected with a wire brush, and the average fiber length was confirmed.

(Incompatibility)

Next, the precursor web was heated up for 30 minutes from 200 degreeC to 340 degreeC in air atmosphere, and the infusible web which consists of infusible carbon fiber was obtained. The amount of oxygen added to the incompatible carbon fiber was 6.6 wt%. In addition, the average fiber length of the pitch type incompatible fiber was 30.5 cm.

(Firing)

Subsequently, the ratio (V1 / V2) of the conveyance speed V1 of the web at the time of incompatibility treatment and the conveyance speed V2 of the web at the time of baking treatment was set to 1.00, and it was continuously baked at 800 degreeC in nitrogen atmosphere, and carbon fiber Although it was intended to obtain a nonwoven fabric consisting of, the cutting of the nonwoven fabric made of carbon fiber was confirmed by shrinkage of the web. The average fiber diameter of carbon fiber was 20.5 micrometers, and the CV value of fiber diameter was 9.2%. In addition, the average fiber length of carbon fiber was 25.9 cm, and fiber length retention was 85%. Moreover, as a result of measuring the tensile strength of the nonwoven fabric which consists of carbon fibers, it was 8.4 N / 5 cm piece.

Furthermore, the obtained incompatible web was baked at 1,500 degreeC over 1 hour from room temperature in argon gas atmosphere, and the nonwoven fabric which consists of carbon fibers was obtained. As a result of evaluating the mechanical properties of this carbon fiber, the tensile elongation was 1.3%, the tensile strength was 1.6 GPa, and the tensile modulus was 235 GPa.

Comparative Example 4

(radiation)

The isotropic pitch of 0% of mesophase rate and aromatic temperature of 258 degreeC which consists of aromatic hydrocarbons was used at 295 degreeC, and it was carried out every minute from the slit by the capillary using the detention which consists of a capillary of 0.2 mm diameter and a length of 2 mm at 295 degreeC. 305 ° C. air was blown at m, and the melt pitch was pulled to prepare a precursor web made of a carbon fiber precursor having an average diameter of 13.5 μm. It was 17.4 cm when the carbon fiber precursor immediately below a metal mold | die was collected with the wire brush, and the average fiber length was confirmed.

(Incompatibility)

Next, the precursor web was heated up for 40 minutes from 200 degreeC to 320 degreeC under air atmosphere, and the infusible web which consists of infusible carbon fiber was obtained. The oxygen addition amount of the incompatible carbon fiber was 8.6% by weight. In addition, the average fiber length of the incompatible fiber was 17.5 cm.

(Firing)

Subsequently, the nonwoven fabric which consists of carbon fiber was manufactured by baking at 800 degreeC in nitrogen atmosphere continuously. Under the present circumstances, ratio (V1 / V2) of the conveyance speed V1 of the web at the time of incompatibilization process, and the conveyance speed V2 of the web at the time of baking process was 1.00. The average fiber diameter of carbon fiber was 12.5 micrometers, and the CV value of fiber diameter was 11.2%. Moreover, the average fiber length of carbon fiber was 16.9 cm, and fiber length retention was 96.6%. Moreover, it was 9.5 N / 5 cm piece as a result of measuring the tensile strength of the nonwoven fabric which consists of carbon fiber.

Furthermore, the obtained incompatible web was baked at 1,500 degreeC over 1 hour from room temperature in argon gas atmosphere, and the nonwoven fabric which consists of carbon fibers was obtained. As a result of evaluating the mechanical properties of this carbon fiber, the tensile elongation was 2.2%, the tensile strength was 0.7 kPa, and the tensile elastic modulus was 29 kPa.

Comparative Example 5

The incompatible web made of infusible carbon fibers prepared in Example 1 was calcined at 2,300 ° C. over 2 hours from room temperature in an argon gas atmosphere to obtain a nonwoven fabric made of carbon fibers. As a result of evaluating the mechanical properties of this carbon fiber, the tensile elongation was 0.63%, the tensile strength was 2.4 kPa, and the tensile elasticity modulus was 510 kPa.

The nonwoven fabric, felt and heat insulating material of this invention can be used as a structural member of an industrial robot arm or an aircraft.

1 barb depth
2 kick-up heights
3 felt
4 needles
5 bed plate
6th Barb from the shortest edge (1st Barb)
7 Needle Depth
8 adjacent barbs

Claims (19)

A nonwoven fabric containing pitch-based carbon fibers, wherein the pitch-based carbon fibers
(Iii) the average fiber diameter (D1) observed with an optical microscope is larger than 2 µm and not larger than 20 µm,
(Ii) 100% of fiber diameter dispersion (S1) with respect to average fiber diameter (D1) observed with the optical microscope is 3 to 20%,
(Iii) a tensile modulus of 80 to 300 GPa, and
(Iv) Tensile elongation is 1.4 to 2.5%, The nonwoven fabric characterized by the above-mentioned. The method of claim 1,
A nonwoven fabric having a tensile modulus of 100 to 300 GPa and a tensile elongation of 1.5 to 2.4% of the pitch-based carbon fiber. The method of claim 1,
The nonwoven fabric whose average fiber diameter (D1) observed with the optical microscope of pitch-type carbon fiber is larger than 10 micrometers and 20 micrometers or less. The method of claim 1,
A nonwoven fabric having a tensile strength of 10 N / 5 cm piece or more. (1) spinning a mesophase pitch to prepare a precursor web containing a carbon fiber precursor,
(2) dissolving the precursor web in an oxidizing gas atmosphere to produce an infusible web containing carbon fibers having an oxygen addition amount of 8 to 15% by weight, and
(3) firing the incompatible web at 800 to 1,800 ° C;
The manufacturing method of the nonwoven fabric containing each process. The method of claim 5, wherein
The manufacturing method which performs spinning by a melt blow method. The method of claim 5, wherein
The manufacturing method whose average fiber length of the carbon fiber precursor of a precursor web is 4-25 cm. The method of claim 5, wherein
The manufacturing method whose oxygen addition amount of the carbon fiber of an infusible web is 9-12 weight%. The method of claim 5, wherein
The manufacturing method whose fiber length retention (%) represented by following formula (I) before and after baking is 90% or more.
Fiber Length Retention Rate = 100 × L ¹ / L ⁰ (Ⅰ)
L ⁰ : fiber length before firing
L ¹ : fiber length after firing Felt obtained by needle punching the nonwoven fabric of Claim 1. The method of claim 10,
The interlayer peel strength of the thickness direction is 0.25 N / 5 cm piece or more. The method of claim 10,
The average fiber diameter of carbon fiber is larger than 10 micrometers, and it is 20 micrometers or less, and the felt has an apparent weight of 250-1,000 g / m <2>. Graphitized felt obtained by heat-processing the felt of Claim 10 at 2,000-3,500 degreeC. (1) spinning a mesophase pitch to prepare a precursor web containing a carbon fiber precursor,
(2) infusing the precursor web in an oxidizing gas atmosphere to produce an infusible web containing carbon fibers having an oxygen addition amount of 8 to 15% by weight,
(3) firing the incompatible web at 800 to 1,800 ° C. to produce a nonwoven fabric, and
(4) needle punching the nonwoven fabric,
The manufacturing method of the felt containing each process. The method of claim 14,
The manufacturing method which needle-punches a nonwoven fabric with the punch number of 15-100 times / cm <2> with the needle whose barb depth is 0.15 mm or more. The composite obtained by impregnating resin in the felt of Claim 10. The composite obtained by impregnating resin in the graphitized felt of Claim 13. The heat insulating material obtained by heat-processing the composite of Claim 16 at 500-2,200 degreeC. (1) A composite is prepared by impregnating the felt of claim 10 in a resin,
(2) heat-processing a composite at 500-2,200 degreeC,
The manufacturing method of the heat insulating material containing each process.

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