JP2016079337A - Carbon fiber-reinforced plastic and method for producing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a carbon fiber-reinforced plastic, while activating the size enlargement properties and moldability when a base material made of a discontinuous carbon fiber is used, having excellent mechanical properties in a desired direction in a reduced carbon fiber amount and further having satisfactory surface properties, and to provide a method for producing the same.SOLUTION: There is provided a carbon fiber reinforced plastic composed of a carbon fiber reinforced thermoplastic resin composition obtained by blending, to 100 pts.wt. of a polyamide resin (a), carbon fiber (b) of 10 to 120 pts.wt. and copper halide (c) and/or its derivative of 0.001 to 5 pts.wt., in which the weight average fiber length of the carbon fiber is 20 to 100 mm, and the average value of the orientation degree of the carbon fiber is 2.0 to 10.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a carbon fiber reinforced plastic and a method for producing the same.

Thermoplastic composite materials reinforced with short fibers of thermoplastic resins are widely used in injection molding applications such as electrical and electronic fields, automobiles, building materials, and general industrial equipment because of their excellent mechanical properties and moldability. However, it may not be applicable to parts that require particularly high strength, such as large molded articles exceeding 1 m ² and structural members, due to concerns regarding molding restrictions and strength reduction due to welds. For this reason, GMT (Glass-Mat reinforced Thermoplastics) impregnated with glass fiber (GF) mat and resin or SMC (Sheet Molding Compound) material impregnated with short fiber chopped resin are used for these applications. Stamping has been performed. Conventionally, thermosetting resins have been used for GMT and SMC resins, but in recent years, development with thermoplastic resins has been promoted from the viewpoint of improving productivity.

  In addition, carbon fiber reinforced plastic (CFRP [Carbon Fiber Reinforced Plastic]) consisting of carbon fiber and matrix resin is excellent in mechanical properties, light weight, corrosion resistance, etc. Has been deployed. As a method for producing CFRP, there is a method using a so-called prepreg impregnated with a resin in advance, but when it is required to widen the range of the shape of CFRP that can be molded and to shorten the time required for molding. For example, when mass production is required, such as automobile parts and electronic equipment parts, a carbon fiber base material (dry carbon fiber base material) substantially free of resin is formed into a predetermined shape. A method of forming a desired CFRP by shaping and impregnating it with a matrix resin is often used.

  In such a method of molding CFRP by impregnating a dry carbon fiber base material with a matrix resin, CFRP formed using a base material formed using continuous carbon fibers is excellent in mechanical properties, Since the continuous carbon fiber is difficult to move at the stage of shaping or molding, there is a problem in moldability (shape shaping) into a desired shape. On the other hand, CFRP molded using a base material formed using discontinuous carbon fibers is excellent in moldability (formability) because carbon fibers are easy to move, but only those having low mechanical properties can be obtained. It was.

  On the other hand, as a technique for improving the formability of the sheet-like base material, moldability to CFRP and mechanical properties, for example, a sheet-like base material made of discontinuous carbon fibers is impregnated with a matrix resin, Proposed is a carbon fiber reinforced plastic in which the proportion of carbon fibers having a length of 10 mm or more is 60% by weight or more of the total carbon fibers, and the average value of the orientation degree of the carbon fibers contained in the sheet-like substrate is in the range of 2 to 10. (For example, refer to Patent Document 1).

  On the other hand, as a technique for improving the heat resistance and the like of a fiber reinforced composite material using a polyamide resin, a fiber reinforced composite material including a reinforced fiber, a polyamide resin, and a copper compound has been proposed (see, for example, Patent Documents 2 to 4). .

International Publication No. 2012/165076 JP 2014-118426 A Special table 2013-540884 gazette JP 2014-177117 A

  Although the technology described in Patent Document 1 can achieve both formability (shaping property) and mechanical properties in a specific direction, the surface appearance of a large molded product is different from the difference in molding shrinkage due to the orientation of carbon fibers. There was a problem to be reduced. In addition, although the heat resistance can be improved by the techniques described in Patent Documents 2 to 4, these techniques are fiber reinforced composites that are unlikely to cause poor appearance originally such as randomly oriented carbon fiber base materials and fabrics. The target is a material, and the problem of poor surface appearance due to the orientation of carbon fibers is not considered at all.

  Therefore, the object of the present invention is to have excellent mechanical properties in a desired direction with a small amount of carbon fiber while taking advantage of good formability and moldability when using a base material composed of discontinuous carbon fibers, An object of the present invention is to provide a carbon fiber reinforced plastic having a good surface appearance and a method for producing the same.

  In order to solve the above-mentioned problems, the carbon fiber reinforced plastic of the present invention comprises (b) 10 to 120 parts by weight of carbon fiber, (c) copper halide and / or 100 parts by weight of polyamide resin. A carbon fiber reinforced plastic composed of a carbon fiber reinforced thermoplastic resin composition containing 0.001 to 5 parts by weight of the derivative, wherein the carbon fiber has a weight average fiber length of 20 to 100 mm, The average value of the degree of orientation is 2.0 to 10.

  According to the present invention, it is possible to provide a carbon fiber reinforced plastic excellent in mechanical properties, moldability (shapeability), surface appearance (designability) and the like. Therefore, the carbon fiber reinforced plastic of the present invention can be suitably used for various applications that require appearance and design in addition to mechanical properties, such as automobile parts, electrical / electronic parts, building members, and sporting goods parts.

It is a schematic diagram which shows an example of the apparatus used for the carding process in the manufacturing method of the carbon fiber reinforced plastic which concerns on one embodiment of this invention. It is a schematic perspective view of the sample for orientation degree measurement. FIG. 4 is a schematic perspective view of a block-shaped minute region obtained by dividing a measurement sample from three-dimensional image data obtained by X-ray CT, and a schematic diagram when coordinate axes are set thereto. It is a schematic diagram which shows the state which pulled the scanning line of the angle (phi) from one axis | shaft in parallel with respect to the set coordinate axis. It is a schematic diagram which shows a mode that the average crossing length of the part where the carbon fiber in a micro area | region and a scanning line cross | intersect is calculated | required. FIG. 6 is a graph plotting average cross length as a function of scan line angle. FIG. It is a schematic diagram which shows a mode that several average crossing length is plotted as a function of the angle of a scanning line. It is a schematic diagram showing how to obtain the major axis a, minor axis b, and major axis angle φ0 in a graph in which the average crossing length is plotted as a function of the scanning line angle φ. It is the graph which plotted the average transverse length by the function of the angle (phi) of a scanning line in the case where the carbon fiber is orientated at random, and when it is completely oriented in one direction. It is a schematic diagram which shows a mode that a micro area | region is moved with respect to the whole X-ray CT image. It is a graph which shows an example which measured and computed the average value of the main orientation angle and orientation degree.

  Below, this invention is demonstrated in detail with embodiment.

  The carbon fiber reinforced plastic according to the present invention is composed of a carbon fiber reinforced thermoplastic resin composition formed by blending (a) polyamide resin, (b) carbon fiber and (c) copper halide and / or a derivative thereof, The weight average fiber length of the carbon fiber is 20 to 100 mm, and the average value of the orientation degree of the carbon fiber is 2.0 to 10. In the carbon fiber reinforced plastic in which the weight average fiber length of the carbon fiber is 20 to 100 mm and the average value of the orientation degree of the carbon fiber is 2.0 to 10, the copper halide and / or its derivative It has been found that the surface appearance is specifically improved by blending of.

  (A) Polyamide resin used for this invention will not be specifically limited if it has an amide bond in a repeating structure. (A) The polyamide resin can be obtained by a method such as ring-opening polymerization of lactams, polycondensation of diamine and dicarboxylic acid, polycondensation of aminocarboxylic acid, or the like. Examples of lactams include ε-caprolactam, enantolactam, and ω-laurolactam. Examples of the diamine include tetramethylene diamine, hexamethylene diamine, undecamethylene diamine, dodecamethylene diamine, tridecamethylene diamine, 1,9-nonane diamine, 2-methyl-1,8-octane diamine, 2,2,4. -Aliphatic diamines such as trimethylhexamethylenediamine, 2,4,4-trimethylhexamethylenediamine, 5-methylnonamethylenediamine, alicyclic rings such as 1,3-bisaminomethylcyclohexane, 1,4-bisaminomethylcyclohexane And aromatic diamines such as formula diamine, m-phenylenediamine, p-phenylenediamine, m-xylylenediamine, and p-xylylenediamine. Examples of dicarboxylic acids include aliphatic dicarboxylic acids such as adipic acid, suberic acid, azelaic acid, sebacic acid, dimer acid, dodecanedioic acid, 1,1,3-tridecanedioic acid, 1,3-cyclohexanedicarboxylic acid, and the like. And aromatic dicarboxylic acids such as alicyclic dicarboxylic acid, terephthalic acid, isophthalic acid and naphthalenedicarboxylic acid. Examples of the aminocarboxylic acid include ε-aminocaproic acid, 7-aminoheptanoic acid, 8-aminooctanoic acid, 9-aminononanoic acid, 11-aminoundecanoic acid, 12-aminododecanoic acid, 13-aminotridecanoic acid, and the like. Can be mentioned.

  (A) Specific examples of the polyamide resin include, for example, nylon 6, nylon 46, nylon 66, nylon 11, nylon 12, nylon 610, nylon 612, nylon 6/66 copolymer, nylon 6/612 copolymer, nylon MXD (M-xylylenediamine) 6, nylon 9T, nylon 10T, nylon 6T / 66 copolymer, nylon 6T / 6I copolymer, nylon 6T / M5T copolymer, nylon 6T / 12 copolymer, nylon 66 / 6T / 6I copolymer, nylon 6T / 6 copolymers and the like. Two or more of these may be blended. Among these, (b) nylon 6, nylon 66, and nylon 610 that are excellent in adhesion to carbon fibers are preferable, and the strength, rigidity, and surface appearance of the carbon fiber reinforced plastic can be further improved.

  (A) The degree of polymerization of the polyamide resin is not particularly limited, but the relative viscosity measured at 25 ° C. in a 98% concentrated sulfuric acid solution having a resin concentration of 0.01 g / ml is in the range of 1.5 to 7.0. Is preferred. The relative viscosity is more preferably 1.8 or more, further preferably 2.0 or more, and further preferably 2.1 or more. On the other hand, the relative viscosity is more preferably 6.0 or less, further preferably 5.0 or less, and further preferably 3.0 or less.

  The (b) carbon fiber used in the present invention is not particularly limited, but PAN-based or pitch-based carbon fibers are preferably used from the viewpoint of cost and handleability. The fiber diameter of the carbon fiber is preferably 5 to 15 μm.

  (B) The compounding quantity of carbon fiber is 10-120 weight part with respect to 100 weight part of (a) polyamide resin. When the blending amount of the carbon fiber is less than 10 parts by weight, the mechanical properties of the carbon fiber reinforced plastic deteriorate. As for the compounding quantity of carbon fiber, 50 weight part or more is preferable. On the other hand, when the blending amount of the carbon fiber exceeds 120 parts by weight, the surface appearance of the carbon fiber reinforced plastic is remarkably deteriorated. The amount of carbon fiber is preferably 100 parts by weight or less.

  The carbon fiber reinforced thermoplastic resin composition used in the present invention is characterized by blending (c) copper halide and / or a derivative thereof. As described above, carbon fiber reinforced plastics having an average degree of orientation of carbon fibers in the range of 2.0 to 10 can achieve both formability (formability) and mechanical properties in a specific direction. Due to the difference in molding shrinkage due to fiber orientation, there has been a problem that the surface appearance of a large-sized molded product is lowered. On the other hand, in the present invention, in the carbon fiber reinforced plastic in which the weight average fiber length of the carbon fibers is 20 to 100 mm and the average value of the orientation degree of the carbon fibers is 2.0 to 10, (c) halogen The surface appearance can be specifically improved by blending copper chloride and / or its derivatives.

  Examples of the copper halide include copper iodide, copper bromide, and copper chloride. Examples of the copper halide derivatives include complex salts of these copper halides with mercaptobenzimidazole. Two or more of these may be blended. Among these, copper iodide, a complex salt of mercaptobenzimidazole and copper iodide is preferable.

  (C) The compounding quantity of a copper halide and / or its derivative (s) is 0.001-5 weight part with respect to 100 weight part of (a) polyamide resin. (C) When the blending amount of the copper halide and / or derivative thereof is less than 0.001 part by weight, the surface appearance is deteriorated. (C) The amount of copper halide and / or its derivative is preferably 0.002 parts by weight or more. On the other hand, even if the amount of (c) copper halide and / or its derivative exceeds 5 parts by weight, no improvement in the surface appearance improvement effect is observed. (C) The amount of copper halide and / or its derivative is preferably 1 part by weight or less. (C) The blending amount of copper halide and / or its derivative refers to the blending amount when blending only one of copper halide and its derivative, and blends both copper halide and its derivative. If so, refer to the total amount of these.

  The weight fiber length of the carbon fiber contained in the carbon fiber reinforced plastic of the present invention is 20 to 100 mm. When the weight average fiber length of the carbon fibers is less than 20 mm, the mechanical properties of the carbon fiber reinforced plastic deteriorate. On the other hand, when the weight average fiber length of the carbon fibers exceeds 100 μm, the moldability is lowered.

Here, the weight average fiber length (Lw) of the carbon fiber can be determined by the following method. A 150 mm × 150 mm plate is cut out from the carbon fiber reinforced plastic and heated for 1 hour in an electric furnace heated to 500 ° C. to burn off organic substances such as polyamide resin. After cooling to room temperature, a small amount of the remaining carbon fiber is sampled and dispersed in water. The carbon fiber-dispersed water is dried in a small petri dish, and an image magnified 50 to 100 times is observed using a microscope. The length of 100 carbon fibers randomly selected from the observed image is measured, and the measured value (mm) (2 decimal places are significant figures) is used for calculation based on the following formula.
Weight average fiber length (Lw) = Σ (Wi × Li) / ΣWi
= Σ (πri ² × Li × ρ × ni × Li) / Σ (πri ² × Li × ρ × ni)
When the fiber diameter ri and the density ρ are constant, the above expression is simplified and becomes the following expression.
= Σ (Li ² × ni) / Σ (Li × ni)
Li: Fiber length of carbon fiber ni: Number of carbon fibers of fiber length Li Wi: Weight of carbon fiber ri: Fiber diameter of carbon fiber ρ: Density of carbon fiber.

  In the carbon fiber reinforced plastic of the present invention, the average value of the degree of orientation of the carbon fibers is 2.0-10. When the average value of the degree of orientation of the carbon fibers is less than 2.0, the anisotropy of mechanical properties is lowered. On the other hand, if the average value of the degree of orientation of the carbon fibers exceeds 10, the moldability and the surface appearance deteriorate. The average value of the degree of orientation of the carbon fibers is preferably 5 or less.

Here, the average value of the orientation degree of the carbon fiber can be obtained by the following method. A measurement sample 11 having a size of 2.58 mm × 2.58 mm × 0.35 mm as shown in FIG. 2 is cut out from the sheet-like base material of carbon fiber reinforced plastic. The measurement sample 11 is placed on the base 12 and divided into 20 × 20 × 10 block-like regions (the pitch is the same as the block size) as described below. X-ray CT: TDM1000 manufactured by Yamato Scientific Co., Ltd. Using -IS, the degree of orientation is measured and calculated by the following method. Note that the orientation direction of the sample 11 in FIG. 2 coincides with the carding direction and the extrusion direction. As software for calculating the degree of orientation, TRI-3D VOL R8.0 manufactured by Ratok System Engineering Co., Ltd. is used.
(1) As shown in FIG. 3, the three-dimensional image data 13 obtained by photographing the sample with X-ray CT is divided into minute block-like regions (minute regions) 14 (the number of divisions is as described above). However, the size of the minute region may be appropriately adjusted in consideration of the size of the carbon fiber.
(2) As shown in FIG. 3, one minute area 14 is extracted from the three-dimensional image data 13 and a coordinate axis is set. Here, in order to make it easy to understand, the description will be made in two dimensions of the X and Y axes.
(3) Next, as shown in FIG. 4, with respect to the set coordinate axis, the scanning line 15 with a certain angle φ is drawn in parallel from one axis. The pitch of the scanning lines may be adjusted as appropriate in consideration of the size of the carbon fiber.
(4) Next, as shown in FIG. 5, the average length (= average crossing length L1) of the portion where the carbon fiber 16 in the minute region 14 and the scanning line 15 intersect is obtained. Since there are actually a plurality of fibers, the average length of the portion that intersects the scanning line 15 is obtained.
(5) Next, as shown in FIG. 6, the average transverse length L1 is plotted on another graph as a function of the angle φ of the scanning line 15 (in FIG. 6, plotted for an angle φ1 of the scanning line 15). Have been).
(6) Next, as shown in FIG. 7, the angle φ of the scanning line 15 is changed, and the operations (4) and (5) are repeated, and the distance from the origin is taken as the average transverse length, and the scanning line 15 Plot as a function of angle φ. In FIG. 7, the figure plotted about average crossing length L1 and average crossing length L2 is shown.
(7) Next, as shown in FIG. 8, in the graph in which the average transverse length is plotted as a function of the scanning line angle φ, the major axis a, minor axis b, and major axis angle φ0 are obtained. The major axis angle φ0 is defined as the main orientation direction, and the ratio of a major axis and minor axis a / b is defined as the degree of orientation in the present invention. In the present invention, the average value of the degree of orientation is adjusted within a predetermined range. When the carbon fibers are completely randomly oriented, the graph shown in FIG. 8 becomes a perfect circle as shown in FIG. 9A (random orientation: a / b = 1). On the other hand, when the carbon fibers are perfectly oriented in one direction, the graph shown in FIG. 8 is a straight line as shown in FIG. 9B (complete orientation: a / b = ∞).
(8) Next, as shown in FIG. 10, the microregion 14 is moved, and the operations (2) to (7) are repeated on the entire X-ray CT image 13. When moving, it may be preferable to overlap the area before the movement.

  An example (within the range defined in the present invention) in which the main orientation angle and the average value of the orientation degree in the present invention are measured and calculated by the above method is illustrated in FIG.

  Examples of means for adjusting the average value of the weight average fiber length and the degree of orientation of the carbon fibers to the above ranges include a method of producing the carbon fibers by the production method described later using the above carbon fibers.

  The carbon fiber reinforced plastic of the present invention preferably has an arithmetic average height (Wa value) of a waviness curve of 3.0 μm or less. When the Wa value is 3.0 μm or less, waviness-like irregularities visually observed on the surface of the carbon fiber reinforced plastic can be reduced, and the surface appearance and design can be further improved. More preferably, it is 2.8 micrometers or less, More preferably, it is 2.5 micrometers or less, Most preferably, it is 2.2 micrometers or less. The lower limit of the Wa value is 0 μm and is not particularly limited. Here, the arithmetic average height (Wa value) of the undulation curve is defined by JIS B0601, using a surface roughness measuring device (manufactured by ACCRTECH), an evaluation length of 20 mm, a test speed of 0. It is the arithmetic average height (Wa) of the undulation curve obtained by measuring the carbon fiber reinforced plastic surface at 6 mm / sec.

  As a means for reducing the Wa value to 3.0 μm or less, for example, by blending the above-mentioned (c) copper halide and / or a derivative thereof, poor dispersion of carbon fibers that cause waviness irregularities of the carbon fiber reinforced plastic And a method for suppressing molding shrinkage (anisotropy).

  The carbon fiber reinforced plastic of the present invention preferably has a surface roughness (Ra value) of 0.3 μm or less. If Ra value is 0.3 micrometer or less, the float of carbon fiber observed visually on the carbon fiber reinforced plastic surface can be reduced, and surface appearance and design nature can be improved more. More preferably, it is 0.27 micrometer or less, More preferably, it is 0.25 micrometer or less, Most preferably, it is 0.22 micrometer or less. Moreover, the lower limit of Ra value is 0 micrometer, and is not specifically limited. Here, the surface roughness is an arithmetic average roughness (Ra) of the carbon fiber reinforced plastic surface under the measurement conditions of an evaluation length of 8 mm and a test speed of 0.6 mm / sec using a surface roughness measuring device (manufactured by ACCRTECH). It can be determined by evaluating the value.

  The carbon fiber reinforced plastic of the present invention is a stabilizer, mold release agent, ultraviolet absorber, colorant, flame retardant, flame retardant aid, anti-dripping agent, lubricant, fluorescent whitening as long as the effects of the present invention are not impaired. Agents, luminous pigments, fluorescent dyes, flow modifiers, impact modifiers, crystal nucleating agents, inorganic or organic antibacterial agents, photocatalytic antifouling agents, infrared absorbers, photochromic agents and other additives, other than carbon fibers These fillers and thermosetting resins may be blended.

  Examples of the stabilizer include an antioxidant and a light stabilizer. By blending these stabilizers, mechanical properties, moldability, heat resistance and durability can be further improved.

  Examples of mold release agents include fatty acids, fatty acid metal salts, oxy fatty acids, fatty acid esters, aliphatic partially saponified esters, paraffins, low molecular weight polyolefins, fatty acid amides, alkylene bis fatty acid amides, aliphatic ketones, modified silicones, and the like. Can do. By blending these release agents, mechanical properties, moldability, heat resistance and durability can be further improved.

  Examples of the flame retardant include bromine flame retardant, chlorine flame retardant, phosphorus flame retardant, nitrogen compound flame retardant, silicone flame retardant, and other inorganic flame retardants. From the viewpoint of further improving flame retardancy and mechanical properties, it is preferable to combine two or more of the above flame retardants.

  (B) It is not specifically limited as fillers other than carbon fiber, Any fillers, such as plate shape, a powder form, and a granular form, can be used. Specifically, metal silicates such as talc, zeolite, sericite, mica, kaolin, clay, pyrophyllite, bentonite, metal oxides such as magnesium oxide, alumina, zirconium oxide, iron oxide, calcium carbonate, magnesium carbonate , Carbonates such as dolomite, metal sulfates such as calcium sulfate and barium sulfate, glass beads, ceramic beads, metal hydroxides such as boron nitride, calcium phosphate, calcium hydroxide, magnesium hydroxide and aluminum hydroxide, glass flakes , Glass powder, glass balloon, carbon black, silica, graphite, montmorillonite, beidellite, nontronite, saponite, hectorite, saconite, etc. And various clay minerals such as zeolite, zirconium phosphate and titanium phosphate, and lamellar silicates such as swellable mica such as Li type fluorine teniolite, Na type fluorine teniolite, Na type tetrasilicon fluorine mica, Li type tetrasilicon fluorine mica, etc. . Two or more of these may be blended.

Next, the manufacturing method of the carbon fiber reinforced plastic of this invention is demonstrated. (B) Examples of a method for setting the weight average fiber length of carbon fibers to 20 to 100 mm include a method using a sheet-like base material in which discontinuous carbon fibers are dispersed, and cutting continuous carbon fibers into an extruder. Examples of the method for producing the carbon fiber reinforced plastic of the present invention include the following methods.
(1) (b) After forming a sheet-like substrate having a carbon fiber weight average fiber length of 20 to 100 mm and an average degree of carbon fiber orientation of 2.0 to 10, the sheet-like substrate. A method of impregnating a resin composition comprising (a) a polyamide resin and (c) a copper halide and / or a derivative thereof.
(2) (a) Polyamide resin and (c) Copper halide and / or derivative thereof and continuous carbon fiber are put into an extruder and dispersed while cutting the continuous carbon fiber, and a carbon fiber reinforced thermoplastic resin composition After obtaining the product and extruding the carbon fiber reinforced thermoplastic resin composition into a lump or sheet in a molten state, the carbon fiber weight average fiber length is 20 to 100 mm by shaping into a predetermined shape, The method which makes the average value of the orientation degree of carbon fiber 2.0-10.

  In the method (1), it is preferable to form the sheet-like substrate by carding. Carding as used in the present invention refers to discontinuous carbon fiber aggregates by applying a force in approximately the same direction with a comb-like aggregate or the like. It means the operation of aligning and opening carbon fibers. Generally, it is performed using a carding device having a roll having a large number of needle-like protrusions on the surface and / or a roll around which a metallic wire having a saw-like protrusion of a saw is wound. A specific example of the entire carding apparatus will be described later. In carrying out such carding, it is preferable to shorten the time during which the carbon fiber is present in the carding device (residence time) in order to prevent the carbon fiber from being broken. Specifically, it is preferable to transfer the carbon fiber present on the wire wound around the cylinder roll of the carding apparatus to the downstream doffer roll in the shortest possible time. Therefore, in order to promote such a transition, the rotation speed of the cylinder roll is preferably rotated at a high rotation speed such as 300 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. Similarly, in order to reduce damage to the carbon fiber, and to suppress the carbon fiber from being depressed and sinking on the surface of a cylinder roll, a worker roll, a stripper roll (refer to a specific configuration example described later), The clearance between the rolls is preferably widened to some extent as compared with the case of carding ordinary organic fibers. For example, the clearance between each of the cylinder roll, worker roll, and stripper roll is preferably 0.5 mm or more, more preferably 0.7 mm or more, and further preferably 0.9 mm or more.

  FIG. 1 shows an example of an apparatus used for a carding process in a method for producing a carbon fiber reinforced plastic according to an embodiment of the present invention. A carding apparatus 1 shown in FIG. 1 includes a cylinder roll 2, a take-in roll 3 provided on the upstream side in the vicinity of the outer peripheral surface, and a cylinder roll 2 on the downstream side opposite to the take-in roll 3. A doffer roll 4 provided close to the outer peripheral surface, a plurality of worker rolls 5 provided close to the outer peripheral surface of the cylinder roll 2 between the take-in roll 3 and the doffer roll 4, and a worker roll Is mainly composed of a stripper roll 6 provided close to the take-in roll 3, a feed roll 7 and a belt conveyor 8 provided close to the take-in roll 3.

  On the belt conveyor 8, an aggregate of discontinuous carbon fibers 9 having a length of preferably 20 to 100 mm is supplied. The discontinuous carbon fibers 9 are disposed on the outer peripheral surface of the feed roll 7 and then on the outer peripheral surface of the take-in roll 3. Through the outer peripheral surface of the cylinder roll 2. In addition, it is preferable that the aggregate of the discontinuous carbon fibers 9 has a ratio of carbon fibers having a length of 20 mm or more of 60% by weight or more of the total carbon fibers. Up to this stage, the discontinuous carbon fibers 9 are in a cotton-like form. A part of the cotton-like carbon fiber introduced on the outer peripheral surface of the cylinder roll 2 is wound around the outer peripheral surface of each worker roll 5, but this carbon fiber is peeled off by each stripper roll 6 and again the cylinder roll 2. It is returned to the outer peripheral surface of. On the outer peripheral surface of each of the feed roll 7, take-in roll 3, cylinder roll 2, worker roll 5, and stripper roll 6, there are many needles and protrusions standing, The fibers are opened into a single fiber shape by the action of the needle, and at the same time, the orientation direction of most of the carbon fibers is aligned with a specific direction, that is, the rotation direction of the cylinder roll 2. The carbon fiber that has been opened through such a process and whose fiber orientation has been advanced moves onto the outer peripheral surface of the doffer roll 4 as a sheet-like web 10 that is one form of the carbon fiber aggregate. Further, by pulling the web 10 while narrowing the width to a predetermined width, a sheet-like base material made of discontinuous carbon fibers referred to in the present invention is formed. This carding is performed so that the average value of the orientation degree of the carbon fibers contained in the sheet-like base material is intentionally within a range of 2.0 to 10.

  In the carding as described above, the aggregate of discontinuous carbon fibers 9 may be composed of only carbon fibers, but the discontinuous organic fibers, for example, thermoplastic resin fibers are mixed to perform carding. It can also be done. In particular, it is preferable to add a thermoplastic resin fiber when carding, since the breakage of the carbon fiber in the carding can be suppressed. Since carbon fiber is rigid and brittle, it is difficult to be entangled and easily broken. For this reason, a carbon fiber aggregate composed only of carbon fibers has a problem that the carbon fibers are easily cut or the carbon fibers are easily dropped during carding. Therefore, by including thermoplastic resin fibers that are flexible, difficult to break, and easily entangled, it is possible to form a carbon fiber aggregate in which the carbon fibers are hardly cut and the carbon fibers are not easily dropped. Further, as described above, it is also preferable to perform carding by mixing such organic fibers, for example, thermoplastic resin fibers, and after carding, at least a part of the organic fibers is melted and then pressed. . That is, an organic fiber is mixed in a moderately small amount, and is oriented with intentionally having anisotropy so that the average value of the degree of orientation of the carbon fibers is within the above-mentioned predetermined range. By melting at least a part of the organic fiber, the organic fiber has a role of a binder for maintaining the form of the sheet-like base material having a predetermined degree of orientation, and is held by being pressed in that state. It is also preferable to fix it moderately via organic fibers.

It is preferable to apply a needle punch of 300 pieces / cm ² or less to the sheet-like substrate formed by carding. By impregnating a discontinuous carbon fiber sheet-like base material with a needle punch, the impregnation property of the resin can be improved. In the present invention, since the discontinuous carbon fiber orientation is intentionally given a predetermined range of anisotropy, the needle punch is adjusted to a predetermined range by setting it to 300 needles / cm ² or less. While maintaining the anisotropy, the resin impregnation property can be appropriately improved.

  The method for impregnating the carbon fiber sheet-shaped substrate with the matrix resin is not particularly limited. For example, the matrix resin is used as a sheet such as a film or a nonwoven fabric, and the sheet and the carbon fiber sheet-shaped substrate are laminated. A method of melting the matrix resin and impregnating it by applying pressure as necessary is mentioned. Examples of the apparatus for producing a sheet-like substrate by such a method include a double belt press machine and an intermittent press machine. In addition, a carbon fiber sheet-like base material is impregnated with a matrix resin to form a prepreg or semi-preg, and then heated and solidified while being pressurized in an autoclave, highly productive Resin Transfer Molding (RTM), Resin film Infusion (RFI) ), Reaction Injection Molding (RIM), injection molding methods such as vacuum pressure molding, and the like. Among these, RTM and vacuum pressure molding are preferably used from the viewpoint of molding cost. Examples of the RTM include a method in which a matrix resin is pressurized and injected into a cavity formed by a male mold and a female mold, and it is preferable that the cavity is decompressed and the resin is injected. In addition, as a vacuum pressure forming method, for example, a cavity formed by either a male mold or a female mold and a bag material such as a film (for example, nylon film or silicon rubber) is decompressed, and the pressure difference from the atmospheric pressure is achieved. A method of injecting a matrix resin is preferable, and it is preferable to dispose the resin diffusion medium (media) in the preform in the cavity to promote resin impregnation and to separate the media from the composite material after molding.

  In the method (2), as a method for shaping into a predetermined shape, a lump or sheet is charged into a shaping mold in a molten state and shaped into a predetermined shape by clamping. Is mentioned.

  The carbon fiber reinforced plastic of the present invention can be used for various applications such as automobile parts, electrical / electronic parts, building members, sporting goods parts, various containers, daily necessities, household goods and sanitary goods.

  In order to describe the present invention more specifically, examples and comparative examples will be described below, but the present invention is not limited to these examples.

The following materials were used.
(A) Polyamide resin Nylon 6 resin “Amilan” (registered trademark) CM1001 (manufactured by Toray Industries, Inc.)
(B) Carbon fiber PAN-based carbon fiber “Torayca” (registered trademark) T700S (density 1.8, diameter 7 μm, number of filaments 12,000, manufactured by Toray Industries, Inc.)
(C) Copper halide or derivative thereof, copper iodide: CuI (reagent)
Copper complex: 2-mercaptobenzimidazole and copper iodide salt (reagent)
(D) Other additives / auxiliaries: Potassium iodide: KI (reagent)
Heat resistance stabilizer: “ADK STAB” AO80, PEP36 (manufactured by Adeka Corporation).

(Production Example 1) Production of carbon fiber sheet-like base material B1 After carbon fibers were cut to 50 mm, they were put into a cotton opening machine to obtain opened carbon fibers. The opened carbon fiber was again put into a cotton opening machine to obtain a cotton-like carbon fiber having almost no carbon fiber bundle. This cotton-like carbon fiber was put into a carding apparatus having a structure shown in FIG. 1 having a cylinder roll having a diameter of 600 mm to form a sheet-like web made of carbon fiber. The rotation speed of the cylinder roll at this time was 350 rpm, and the speed of the doffer roll was 15 m / min. In this carding process, the carbon fiber was not dropped off or wound around the roll of the carding apparatus. After laminating this web with a cross wrapper, a needle punch of 50 / cm ² was applied to obtain a carbon fiber nonwoven fabric (carbon fiber sheet-like substrate B1).

(Production Example 2) Production of carbon fiber sheet-like base material B2 Nylon 6 discontinuous fibers (single fiber fineness 1.7 dtex, cut length 51 mm, crimp number 12/25 mm, crimp rate when carding) 15%) was mixed at a mass ratio of 90:10 (carbon fiber: nylon 6 fiber) to prepare a carbon fiber / nylon 6 mixed nonwoven fabric (carbon fiber sheet-like substrate B2) by the same method as B1. The swing width of the cross wrapper at this time was 1.2 m, and the winding speed of the nonwoven fabric was 1 m / min. Further, before winding the nonwoven fabric, hot air at 280 ° C. was blown from both sides of the nonwoven fabric, and then the nylon 6 discontinuous fibers were melted and solidified by being sandwiched between cooling rolls in which cooling water was flowed.

(Production Example 3) Production of carbon fiber sheet-like base material B3 A carbon fiber nonwoven fabric (carbon fiber sheet-like base material B3) was obtained in the same manner as in Production Example 1 except that the number of needle punches was 500 / cm ² . .

(Production Example 4) Production of carbon fiber sheet-like base material B4 In order to reinforce the orientation of carbon fibers in the web, the rotation speed of the cylinder roll during carding is set to 550 rpm, and the interval between the cylinder roll and the worker roll is set to A carbon fiber nonwoven fabric (carbon fiber sheet-like base material B4) was produced by setting the amount to 1/2 in the case of Example 1, and further setting the input amount of carbon fiber to 1/2 and the winding speed of the nonwoven fabric to 0.5 m / min. .

(Production Example 5)
(A) Polyamide resin, (c) Copper halide or derivative thereof and (d) Other additives are pre-blended into the compounding recipes (A1 to A5) shown in Table 1, and then the temperature is increased to 250 ° C. Was melt-kneaded and extruded into a film form from a film die to obtain resin films A1 to A5 having a thickness of 100 μm.

  Characteristic evaluation in each example and comparative example was performed by the following method.

(1) Weight average fiber length of carbon fiber A 150 mm × 150 mm plate was cut out from carbon fiber reinforced plastic and heated in an electric furnace heated to 500 ° C. for 1 hour to burn off organic substances such as polyamide resin. After cooling to room temperature, a small amount of the remaining carbon fiber was sampled and dispersed in water. The carbon fiber-dispersed water was dried in a small petri dish, and an image magnified 50 to 100 times using a microscope was observed. The lengths of 100 carbon fibers randomly selected from the observed image were measured, and the measured values (mm) (2 decimal places were significant figures) were used for calculation based on the following formula.
Weight average fiber length (Lw) = Σ (Li ² × ni) / Σ (Li × ni)
Li: Fiber length of carbon fiber ni: Number of carbon fibers of fiber length Li.

(2) Average value of orientation degree of carbon fiber Measurement sample 11 having a size of 2.58 mm × 2.58 mm × 0.35 mm shown in FIG. 2 was cut out from a carbon fiber reinforced plastic sheet-like substrate. The measurement sample 11 is placed on the base 12 and divided into 20 × 20 × 10 block-like regions (the pitch is the same as the block size) as described below. X-ray CT: TDM1000 manufactured by Yamato Scientific Co., Ltd. Using -IS, the degree of orientation was measured and calculated by the following method. Note that the orientation direction of the sample 11 in FIG. 2 coincides with the carding direction and the extrusion direction. Further, TRI-3D VOL R8.0 manufactured by Ratoku System Engineering Co., Ltd. was used as software for calculating the degree of orientation.

(3) Flexural strength and flexural modulus From carbon fiber reinforced plastics, Examples 1 to 6 and Comparative Examples 1 to 4 are in the orientation direction (carding direction), Examples 7 to 9 and Comparative Example 5 are orientation directions ( Samples were cut out in the extrusion discharge direction), and bending strength and bending elastic modulus were evaluated at 23 ° C. according to ISO178.

(4) Surface appearance Using a surface roughness measuring device (manufactured by ACCRTECH), the surface of the carbon fiber reinforced plastic was observed at an evaluation length of 20 mm and a test speed of 0.6 mm / sec, and the waviness curve defined by JIS B0601 The arithmetic average height (Wa value) was measured. Also, using a surface roughness measuring device (manufactured by ACCRTECH), the carbon fiber reinforced plastic surface was observed under the measurement conditions of an evaluation length of 8 mm and a test speed of 0.6 mm / sec, and the arithmetic average roughness (Ra) value was determined. It was measured.

[Examples 1-6, Comparative Examples 1-4]
The resin film shown in Table 2 obtained in Production Example 5 and a carbon fiber sheet-like substrate were laminated, sandwiched between hot plates heated up and down to 260 ° C., pressed at 3 MPa for 10 minutes, and then cooled to room temperature. Thus, a carbon fiber reinforced plastic having a size of 250 mm × 250 mm × wall thickness 2 mmt was produced. Table 2 shows the results of various characteristic evaluations under the above conditions.

  From Examples 1 to 6 and Comparative Example 1, (a) polyamide resin, (b) carbon fiber and (c) copper halide and / or a derivative thereof are used in combination to reduce surface roughness without deteriorating mechanical properties. It can be seen that the surface waviness can be improved, and a carbon fiber reinforced plastic having both mechanical properties comparable to metals and appearance / design can be obtained. If the degree of carbon fiber orientation is low as in Comparative Example 2, the mechanical properties deteriorate. On the other hand, when the degree of carbon fiber orientation is high as in Comparative Example 3, the appearance and design properties deteriorate. With the heat-resistant stabilizer other than the copper-based compound as in Comparative Example 4, the appearance and design properties are not improved.

[Examples 7 to 9, Comparative Example 5]
From the main feeder of a twin-screw extruder (TEX30α manufactured by Nippon Steel Works) set to a cylinder temperature of 260 ° C. and a screw rotation speed of 150 rpm, pre-blended to the compounding formulations (A1 to A5) described in Table 1 as a resin formulation described in Table 3. A continuous carbon fiber was fed into the molten resin from the side feeder holes. It is discharged from an extruder die in a sheet shape with a width of 200 mm and a thickness of 3 mm, sandwiched between hot plates heated up and down to 260 ° C., pressed at 3 MPa for 10 minutes, cooled to room temperature, 250 mm × 250 mm × wall thickness 2 mmt A carbon fiber reinforced plastic was prepared. Table 3 shows the results of various characteristic evaluations under the above conditions.

  The carbon fiber reinforced plastic according to the present invention can be used in various applications such as automobile parts, electrical / electronic parts, building members, sporting goods parts, various containers, daily necessities, household goods and sanitary goods.

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 Sheet-like web 11 Measurement sample 12 Base 13 Three-dimensional image data 14 Micro area 15 Scan line 16 Carbon fiber

Claims (7)

(A) Carbon fiber reinforcement obtained by blending 10 to 120 parts by weight of carbon fiber and (c) 0.001 to 5 parts by weight of copper halide and / or its derivative with respect to 100 parts by weight of polyamide resin A carbon fiber reinforced plastic composed of a thermoplastic resin composition, wherein the weight average fiber length of the carbon fibers is 20 to 100 mm, and the average value of the orientation degree of the carbon fibers is 2.0 to 10 plastic. The carbon fiber reinforced plastic according to claim 1, wherein the (c) copper halide and / or a derivative thereof includes copper iodide and / or a complex of mercaptobenzimidazole and copper iodide. (B) After forming a sheet-like substrate having a carbon fiber weight average fiber length of 20 to 100 mm and an average degree of carbon fiber orientation of 2.0 to 10, the sheet-like substrate is subjected to (a The method for producing a carbon fiber reinforced plastic according to claim 1 or 2, wherein a resin composition comprising (a) a polyamide resin and (c) a copper halide and / or a derivative thereof is impregnated. The manufacturing method of the carbon fiber reinforced plastics of Claim 3 which forms the said sheet-like base material by carding. The manufacturing method of the carbon fiber reinforced plastics of Claim 3 or 4 which gives a needle punch of 300 pieces / cm < ² > or less to the sheet-like base material formed by the said carding. When forming a sheet-like substrate by the carding, by performing a carding by mixing discontinuous carbon fibers and discontinuous organic fibers, after carding, after melting at least a part of the organic fibers, The manufacturing method of the carbon fiber reinforced plastic in any one of Claims 3-5 which gives a press. The (a) polyamide resin and (c) copper halide and / or derivative thereof and continuous carbon fiber are put into an extruder and dispersed while cutting the continuous carbon fiber to obtain a carbon fiber reinforced thermoplastic resin composition. The carbon fiber reinforced thermoplastic resin composition is extruded into a lump or sheet in a molten state, and then shaped into a predetermined shape, whereby the weight average fiber length of the carbon fibers is 20 to 100 mm, and the carbon fibers The manufacturing method of the carbon fiber reinforced plastics of Claim 1 or 2 which makes the average value of degree of orientation of 2.0-10.

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