JP6201630B2 - Carbon fiber mat and method for producing the same - Google Patents

Description

  The present invention relates to a carbon fiber mat excellent in handleability and productivity and a method for producing the same.

  Carbon fiber mats are widely used as fiber base materials for molding carbon fiber reinforced resins. This carbon fiber mat is laminated or arranged at a predetermined position on the entire base material in order to produce a fiber base material for molding carbon fiber reinforced resin. If the fiber mat is wound up in a roll shape and can be unwound as much as necessary from the winding roll, it is excellent in handleability and can contribute to an improvement in productivity. .

  A mat composed of only carbon fibers is usually difficult to maintain in the form of a handleable sheet. Therefore, a binder (for example, binder fibers) is mixed with the aggregate of carbon fibers, and the sheet-like carbon fibers are mixed with the binder. A technique for maintaining the form of a mat is known.

  For example, Patent Document 1 discloses a method in which a mat formed of carbon fiber and crimped thermoplastic resin fiber is calender pressed and the crimped fiber (binder fiber) is melted to fix the form of the mat. However, in this method, since the binder fiber is melted, the produced mat is hard and difficult to wind. Therefore, it is difficult to obtain a carbon fiber mat wound up in a roll shape, which is excellent in handleability as described above and can contribute to improvement in productivity.

  Patent Document 2 discloses a method in which a mat made of carbon fibers and thermoplastic resin fibers (core-sheath fibers) is heated and pressed, and the sheath portion of the core-sheath fibers is fused to fix the form of the mat. Yes. However, even in this method, since at least the sheath portion of the binder fiber is melted, the mat to be produced is hard and difficult to wind, and the same problem as described above remains.

JP-A-2-41427 JP 2011-144473 A

  Therefore, the object of the present invention is carbon that is easy to roll up when rolled up in order to form a flexible sheet that is excellent in handleability and has not been realized by the form fixing by fusion of binder fibers in the prior art as described above. It is in providing a fiber mat and its manufacturing method.

In order to solve the above-mentioned problems, the carbon fiber mat according to the present invention has a carbon fiber having a fiber length in the range of 5 to 50 mm and a nylon 6 having crimps and having a fiber length in the range of 10 to 100 mm. Or a binder fiber containing either nylon 610, and the shape is fixed by heating and pressing at a glass transition point of the binder fiber of + 30 ° C. or higher and a melting point of −10 ° C. or lower, and the apparent density is 0.030. It consists of what is characterized by being in the range of- 0.050 g / cm < ³ > . This heating and pressurization can be performed using, for example, a calendar press machine capable of heating and pressurizing at a temperature lower than the melting point of the binder fiber.

  In such a carbon fiber mat according to the present invention, since it is heated and pressurized at a temperature lower than the melting point of the binder fiber, the binder fiber does not substantially melt and maintains the fiber shape. This is a carbon fiber mat with a fixed form. Since the binder fiber is not melted, that is, it does not harden after being melted, the carbon fiber mat can maintain sufficient flexibility, and a mat with excellent handleability that is easy to wind is realized. Can also improve productivity.

The carbon fiber mat of the present invention, the glass transition point of the binder fiber + 30 ° C. or higher, shape Ru is fixed by heat and pressure at the melting point -10 ° C. or lower. The temperature for heating and pressurization is more preferably a glass transition point of the binder fiber + 50 ° C. or more and a melting point of −15 ° C. or less, and further preferably a glass transition point of the binder fiber + 80 ° C. or more and a melting point. The temperature is −25 ° C. or lower.

In the carbon fiber mat according to the present invention, the apparent density of the carbon fiber mat is preferably in the range of 0.030 to 0.080 g / cm ³ , more preferably 0.030 to 0.070 g / cm2. The range of cm ³ , more preferably 0.035 to 0.050 g / cm ³ , but in the present invention, the binder fiber in the present invention has crimps, and either nylon 6 or nylon 610 is used. From the results of Examples (Examples 1 to 5), which will be described later, which satisfy the structural requirement of containing, the apparent density of the carbon fiber mat is defined in the range of 0.030 to 0.050 g / cm ³ . By making the apparent density within the appropriate range, it becomes a mat that is appropriately soft and has a roll-like carbon fiber mat that is easy to wind up and easy to handle. It becomes possible. However, if the apparent density is too low, the sheet becomes thicker accordingly, which causes a problem that winding cannot be performed or the winding shape is deteriorated.

Further, the binder fiber, that have a crimp. When the binder fiber has crimps, the entanglement with the carbon fiber is improved, the carbon fibers are easily bonded to each other by the binder fiber, and the shape fixability of the carbon fiber mat is improved.

The type of the binder fiber is not particularly limited, but the fiber is preferably made of a thermoplastic resin. Examples of the thermoplastic resin constituting the binder fiber include nylon 6, nylon 66, nylon 610, nylon 410, nylon 56, nylon 9T, polyethylene, polypropylene, polyethylene terephthalate, polypropylene terephthalate, polybutylene terephthalate, polylactic acid, and polyphenylene sulfide. Preferably used. Of these, the present invention is limited to binder fibers containing either nylon 6 or nylon 610. Moreover, the binder fiber may be comprised only with the thermoplastic resin, and may be comprised in the state in which the some thermoplastic resin was mixed. For example, a binder fiber having a core-sheath structure in which two or more kinds of thermoplastic resins are blended or a low melting point thermoplastic resin is used as a sheath component may be used.

As the fiber length of the binder fiber, area by the near of 10 to 100 mm. A more preferable range is a range of 30 to 80 mm, and a further preferable range is a range of 38 to 76 mm. If the fiber length of the binder fiber is too short, the entanglement with the carbon fiber will be lowered and the function as a binder will be lowered, and if it is too long, it will be difficult to disperse the binder fiber uniformly or the mixing ratio of the binder fiber will be controlled. It becomes difficult.

  It is preferable that the binder fiber is blended at an appropriate mixing ratio from the viewpoint of ensuring the function as a binder and preventing the binder fiber from becoming too much with respect to the carbon fiber. The mixing ratio of the binder fibers is preferably in the range of 1 to 50% by weight, more preferably in the range of 5 to 40% by weight, and still more preferably in the range of 10 to 30% by weight.

  A sheet-like carbon fiber mat composed of carbon fibers and binder fibers before the shape is fixed by heating and pressing can be produced by, for example, a carding device or an air laid device, and further the above-mentioned binder fibers by a carding device or an air laid device. The mixing ratio can be adjusted.

  Here, carding is an operation of aligning discontinuous fibers or opening the fibers by applying a force in approximately the same direction with a comb-like discontinuous fiber assembly. Say. Generally, it is carried out using a carding apparatus having a roll having a large number of needle-like projections on the surface and / or a roll around which a metallic wire having a saw-like projection of a saw is wound. In carrying out such carding, it is preferable to shorten the time (residence time) in which the carbon fiber is present in the carding apparatus in order to prevent the carbon fiber from being broken. Specifically, it is preferable to transfer the carbon fibers present on the wire wound around the cylinder roll of the carding apparatus to the doffer roll in as short a time as possible. Therefore, in order to promote such transition, the rotation speed of the cylinder roll is preferably rotated at a high rotation speed such as 150 rpm or more. For the same reason, the surface speed of the doffer roll is preferably a high speed such as 10 m / min or more.

  The carding device is not particularly limited and a general device can be used. For example, as shown in FIG. 1, the carding apparatus 1 includes a cylinder roll 2, a take-in roll 3 provided on the upstream side near the outer peripheral surface, and a downstream side opposite to the take-in roll 3. And a plurality of worker rolls provided close to the outer peripheral surface of the cylinder roll 2 between the take-in roll 3 and the doffer roll 4. 5, a stripper roll 6 provided close to the worker roll 5, a feed roll 7 and a belt conveyor 8 provided close to the take-in roll 3. For example, discontinuous carbon fiber bundles 9 and binder fibers 10 are supplied onto the belt conveyor 8, and these are fed onto the outer peripheral surface of the cylinder roll 2 via the outer peripheral surface of the feed roll 7 and then the outer peripheral surface of the take-in roll 3. be introduced. Up to this stage, the carbon fiber bundle is unwound and becomes an aggregate of cotton-like carbon fiber bundles. A part of the aggregate of the carbon-like carbon fiber bundle and the binder fiber introduced on the outer peripheral surface of the cylinder roll 2 are wound around the outer peripheral surface of the worker roll 5, but this is peeled off by the stripper roll 6 and again in the cylinder. Returned to the outer peripheral surface of the roll 2. A large number of needles and protrusions are present on the outer peripheral surface of each of the feed roll 7, the take-in roll 3, the cylinder roll 2, the worker roll 5, and the stripper roll 6, and carbon fiber is The bundle is opened by the action of the needle, and moves on the outer peripheral surface of the doffer roll 4 as a sheet-like web 11 which is one form of an aggregate of carbon fibers and binder fibers. The sheet-like web 11 is subjected to predetermined heating and pressurization according to the present invention, and the shape of the carbon fiber mat is fixed by binder fibers that are not melted.

The carbon fibers used in the present invention are not particularly limited, but high strength and high modulus carbon fibers can be used, and these may be used alone or in combination of two or more. Among these, PAN-based, pitch-based, rayon-based carbon fibers and the like can be mentioned. From the viewpoint of the balance between the strength and elastic modulus of a molded product obtained using the carbon fiber mat according to the present invention, PAN-based carbon fibers are more preferable. The density of the carbon fiber is preferably one of 1.65~1.95g / cm ^3, further more preferably from 1.70~1.85g / cm ^3. When the density is too high, the resulting carbon fiber reinforced resin molded product is inferior in light weight performance, and when the density is too low, the mechanical properties of the obtained carbon fiber reinforced resin molded product may be lowered.

  Airlaid is a method for producing a nonwoven fabric sheet of short fibers. A discontinuous fiber assembly is uniformly dispersed by placing it on a flow of air, and it is dropped on a wire mesh and collected by suction. This is an operation to obtain In the present invention, the airlaid device is not particularly limited and a general device can be used.

  Next, airlaid methods will be described. Examples of general airlaid methods include the Honshu Paper Manufacturing Method, the Croyer Method, the Dunweb Method, the J & J Method, the KC Method, and the Scott Method. (See the Society for Non-woven Fabric Research, 1993)).

  For example, as shown in FIG. 2, the airlaid device 12 has a cylindrical drum 13 having pores that rotate in reverse to each other and a pin cylinder 14 installed in each drum 13, and a carbon fiber together with a large amount of air. A single bundle or a carbon fiber bundle and a thermoplastic resin fiber are blown to the drum 13, opened by the pin cylinder 14 in the drum 13, discharged from the pores, and dropped onto the wire 15 that travels below. Here, the air used for air feeding is sucked into a suction box 16 installed under the wire 15, and the opened carbon fiber bundle alone or the opened carbon fiber bundle and the thermoplastic resin fiber remains on the wire 15. To form a carbon fiber sheet.

  In addition, the carbon fiber may be subjected to a surface treatment for the purpose of improving the adhesion between the carbon fiber and the matrix resin in the carbon fiber reinforced resin molded product to be obtained. Examples of surface treatment methods include electrolytic treatment, ozone treatment, and ultraviolet treatment. In addition, a sizing agent is applied to the carbon fiber for the purpose of preventing the fluff of the carbon fiber, improving the convergence of the carbon fiber, and improving the adhesion between the carbon fiber and the matrix resin in the molded product. It doesn't matter. Although it does not specifically limit as a sizing agent, The compound which has functional groups, such as an epoxy group, a urethane group, an amino group, and a carboxyl group, can be used, These may use 1 type or 2 types or more together.

As the fiber length of the carbon fibers in the carbon fiber mat of the present invention, area by the near of 5 to 50 mm. More preferably, it is the range of 10-40 mm, More preferably, it is the range of 15-35 mm. If the fiber length of the carbon fiber is too short, it will be difficult to maintain the form of the sheet-like carbon fiber mat, and if it is too long, it will be difficult to uniformly disperse the binder fiber.

The present invention is a carbon fiber having a fiber length in the range of 5 to 50 mm, and a carbon fiber having a crimp and having a fiber length in the range of 10 to 100 mm and containing either nylon 6 or nylon 610. Carbon in which the fiber mat is fixed in shape by heating and pressing at a glass transition point of the binder fiber of + 30 ° C. or higher and a melting point of −10 ° C. or lower, and an apparent density is in the range of 0.030 to 0.050 g / cm ^3. A method for producing a carbon fiber mat, characterized by producing a fiber mat, is also provided. The temperature for heating and pressurization is preferably a glass transition point of the binder fiber + 50 ° C. or higher and a melting point of −15 ° C. or lower, more preferably a glass transition point of the binder fiber + 80 ° C. or higher, melting point−25. The temperature is below ℃.

  The apparatus for heating / pressing the carbon fiber mat of the present invention is not particularly limited, and a general heating / pressurizing apparatus can be used as long as it has a function capable of fixing the shape by heating / pressing. For example, a batch-type press device may be used, or a continuous press device such as a calendar roll press machine or a laminate press machine may be used.

  Thus, according to the carbon fiber mat and the method for producing the same according to the present invention, the roll of the sheet-like carbon fiber mat is flexible without being broken when the carbon fiber mat is laminated. It is possible to provide a carbon fiber mat excellent in handleability and productivity that can be easily wound into a shape.

It is a schematic block diagram which shows an example of the carding apparatus for producing the carbon fiber mat before a heating and pressurization in this invention. It is a schematic block diagram which shows an example of the airlaid apparatus for producing the carbon fiber mat before a heating and pressurization in this invention.

  Below, the carbon fiber mat concerning the present invention and its manufacturing method are explained based on an example and a comparative example. First, physical properties and characteristics measurement and evaluation methods used in Examples and Comparative Examples will be described.

(1) Apparent density The obtained carbon fiber mat was cut into a 30 cm square, and the volume was calculated by measuring the length, width, and height with a ruler or caliper, and the weight of the carbon fiber mat was measured. The apparent density in the present invention was obtained by dividing by 5 and performing a simple average on 5 samples.

(2) Evaluation of windability ○ The carbon fiber mat after the hot press has good handleability and is excellent in winding shape when wound on a paper tube. Although the handleability is slightly bad, the winding shape when winding on the paper tube is △, the one that stretches or tears greatly when the carbon fiber mat is pulled, and the winding shape when winding on the paper tube Bad ones were marked with x. In addition, what was determined as (circle) and (triangle | delta) was set as the pass, and x was set as the disqualification.

Example 1
A carbon fiber bundle (T700SC-12k) manufactured by Toray Industries, Inc. was cut to a fiber length of 15 mm, and the cut carbon fiber bundle and nylon 6 short fiber (short fiber fineness 1.7 dtex, fiber length 51 mm, crimped number 12 mountain / 25 mm, crimp rate 15%, melting point 225 ° C., glass transition point 48 ° C.) were mixed at a mass ratio of 90:10 and put into a carding apparatus. The web coming out of the carding apparatus was cross-wrapped to produce a sheet made of carbon fiber and nylon 6 fiber having a width of 1.5 m and a basis weight of 100 g / cm ² . The obtained sheet was pressed with a calendar roll press machine (both upper and lower rolls made of mirror metal) at a load of 6 t, a clearance of 100 μm, a feed rate of 0.5 m / min, and a roll temperature of 180 ° C. A carbon fiber mat was obtained. The apparent density of the obtained carbon fiber mat was 0.044 g / cm ³ . In addition, the obtained carbon fiber mat is excellent in handleability because it is fixed in form by heating and pressurization, it does not tear even if the sheet is slightly tensioned, and can be smoothly wound around the paper tube, The winding shape was also beautiful. The results are shown in Table 1 together with the following examples and comparative examples.

Example 2
A sheet having a width of 1.5 m and a basis weight of 100 g / cm ² made of carbon fiber and nylon 6 fiber was produced in the same manner as in Example 1 except that the mixing ratio of the carbon fiber bundle and nylon short fiber was 80:20 by mass ratio. did. The obtained sheet was pressed and wound on a paper tube in the same manner as in Example 1 except that the feed speed was 1.0 m / min and the roll temperature was 200 ° C. to obtain a carbon fiber mat. The apparent density of the obtained carbon fiber mat was 0.042 g / cm ³ . In addition, the obtained carbon fiber mat is excellent in handleability because it is fixed in form by heating and pressurization, it does not tear even if the sheet is slightly tensioned, and can be smoothly wound around the paper tube, The winding shape was also beautiful.

Example 3
Except for the fiber length of the carbon fiber bundle being 50 mm and the fiber length of the nylon 6 short fiber being 38 mm, the width of the carbon fiber and the nylon 6 fiber is 1.5 m and the basis weight is 100 g / cm ² except that the fiber length is 38 mm. A sheet was produced. The obtained sheet was pressed and wound on a paper tube in the same manner as in Example 1 except that the roll temperature was 100 ° C. and the feed rate was 2 m / min, to obtain a carbon fiber mat. The apparent density of the obtained carbon fiber mat was 0.039 g / cm ³ . In addition, the obtained carbon fiber mat is excellent in handleability because it is fixed in form by heating and pressurization, it does not tear even if the sheet is slightly tensioned, and can be smoothly wound around the paper tube, The winding shape was also beautiful.

Example 4
Except for the fiber length of the carbon fiber bundle being 25 mm and the fiber length of the nylon 6 short fiber being 76 mm, the width of the carbon fiber and the nylon 6 fiber is 1.5 m and the basis weight is 100 g / cm ² except that the fiber length is 76 mm. A sheet was produced. The obtained sheet was pressed in the same manner as in Example 1 except that the roll temperature was set to 150 ° C., and wound around a paper tube to obtain a carbon fiber mat. The apparent density of the obtained carbon fiber mat was 0.035 g / cm ³ . The obtained carbon fiber mat was fixed in form by heating and pressurization, but when the sheet was tensioned, the carbon fiber mat tended to stretch slightly, but it could be smoothly wound onto a paper tube. The winding shape was also beautiful.

Example 5
A carbon fiber bundle (T700SC-12k) manufactured by Toray Industries, Inc. was cut to a fiber length of 10 mm, and the cut carbon fiber bundle and nylon 610 short fiber (short fiber fineness 1.7 dtex, fiber length 51 mm, crimped number 12 mountain / 25 mm, crimp rate 15%, melting point 225 ° C., glass transition point 50 ° C.) were mixed at a mass ratio of 70:30 and put into a carding apparatus. The web coming out of the carding apparatus was cross-wrapped to produce a sheet made of carbon fiber and nylon 610 fiber having a width of 1.5 m and a basis weight of 100 g / cm ² . The obtained sheet was pressed in the same manner as in Example 1 except that the roll temperature was 120 ° C., and wound around a paper tube to obtain a carbon fiber mat. The apparent density of the obtained carbon fiber mat was 0.032 g / cm ³ . The obtained carbon fiber mat was fixed in form by heating and pressurization, but when the sheet was tensioned, the carbon fiber mat tended to stretch slightly, but it could be smoothly wound onto a paper tube. The winding shape was also beautiful.

Reference Example 6
A carbon fiber bundle (T700SC-12k) manufactured by Toray Industries, Inc. was cut to a fiber length of 10 mm, and the cut carbon fiber bundle and polyphenylene sulfide (PPS) short fiber (short fiber fineness 2.0 dtex, fiber length 51 mm, crimped number) 12 crests / 25 mm, crimp rate 15%, melting point 280 ° C., glass transition point 90 ° C.) were mixed at a mass ratio of 90:10 and put into a carding apparatus. The web that came out was cross-wrapped to produce a sheet of carbon fiber and PPS fiber having a width of 1.5 m and a basis weight of 100 g / cm ² . The obtained sheet was pressed in the same manner as in Example 1 except that the roll temperature was 240 ° C., and wound around a paper tube to obtain a carbon fiber mat. The apparent density of the obtained carbon fiber mat was 0.054 g / cm ³ . In addition, the obtained carbon fiber mat is excellent in handleability because it is fixed in form by heating and pressurization, it does not tear even if the sheet is slightly tensioned, and can be smoothly wound around the paper tube, The winding shape was also beautiful.

Reference Example 7
A carbon fiber bundle (T700SC-12k) manufactured by Toray Industries, Inc. was cut to a fiber length of 15 mm, and the cut carbon fiber bundle and a polyamide (nylon 6) short fiber (single fiber fineness of 1.7 dtex long fiber at a fiber length of 5 mm 2) are mixed at a mass ratio of 90:10 and put into an air laid apparatus as shown in FIG. 2, and a sheet-like carbon fiber having a basis weight of 100 g / m ² made of carbon fiber and nylon 6 fiber. Aggregates were formed. The obtained sheet was pressed in the same manner as in Example 1 except that the roll temperature was 210 ° C., and wound around a paper tube to obtain a carbon fiber mat. The apparent density of the obtained carbon fiber mat was 0.061 g / cm ³ . In addition, the obtained carbon fiber mat is excellent in handleability because it is fixed in form by heating and pressurization, it does not tear even if the sheet is slightly tensioned, and can be smoothly wound around the paper tube, The winding shape was also beautiful.

Comparative Example 1
A carbon fiber mat was obtained in the same manner as in Example 1 except that the sheet obtained in Example 1 was pressed at a roll temperature of 250 ° C. The apparent density of the obtained carbon fiber mat was 0.089 g / cm ³ . The obtained carbon fiber mat is heated and pressurized at a temperature equal to or higher than the melting point (225 ° C.) of the binder fiber, and is excellent in handleability. However, since the binder fiber is melted, the sheet is rigid. Thus, the paper tube could not be wound smoothly and the winding shape was not good.

Comparative Example 2
A carbon fiber mat was obtained in the same manner as in Example 1 except that the sheet obtained in Example 1 was pressed at a roll temperature of 40 ° C. The apparent density of the obtained carbon fiber mat was 0.029 g / cm ³ . In addition, the obtained carbon fiber mat is heated and pressurized at a temperature below the glass transition point (48 ° C.) of the binder fiber, so the shape fixing effect is insufficient, and the sheet is easily torn and wound into a paper tube. Could not be performed smoothly, and the winding shape was not good.

  The carbon fiber mat and the manufacturing method thereof according to the present invention can be applied to molding of any carbon fiber reinforced resin using the carbon fiber mat.

DESCRIPTION OF SYMBOLS 1 Carding apparatus 2 Cylinder roll 3 Take-in roll 4 Doffer roll 5 Worker roll 6 Stripper roll 7 Feed roll 8 Belt conveyor 9 Discontinuous carbon fiber 10 Binder fiber 11 Sheet-like web 12 Airlaid apparatus 13 Drum 14 Pin cylinder 15 Wire 16 suction box

Claims (3)

Carbon fiber fiber length is in the range of 5 to 50 mm, the fiber length has a crimp consists binder fibers containing either nylon 6 or nylon 610 in the range of 10 to 100 mm, the glass binder fiber Carbon whose shape is fixed by heating and pressurizing at a transition point of + 30 ° C. or higher and a melting point of −10 ° C. or lower, and whose apparent density is in the range of 0.030 to 0.050 g / cm ^3. Fiber mat. The carbon fiber mat according to claim 1 , wherein the mixing ratio of the binder fibers is in the range of 1 to 50% by weight. A carbon fiber mat comprising a carbon fiber having a fiber length in the range of 5 to 50 mm and a binder fiber having crimps and having a fiber length in the range of 10 to 100 mm and containing either nylon 6 or nylon 610 ; A carbon fiber mat having an apparent density in the range of 0.030 to 0.050 g / cm ³ is produced by fixing the shape by heating and pressing at a glass transition point of the binder fiber of + 30 ° C. or higher and a melting point of −10 ° C. or lower. A method for producing a carbon fiber mat, comprising:

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