JP6146063B2 - Carbon long fiber reinforced polyamide composite for compression molding - Google Patents

Description

  The present invention relates to a composite material composed of long carbon fibers and a polyamide resin. Specifically, the present invention relates to a composite material comprising a long-chain aliphatic polyamide and a long-chain methylene terephthalamide copolymer and carbon long fibers. More specifically, the present invention relates to a composite material for a structural material having a low water absorption rate, a high elastic modulus and strength even under equilibrium water absorption, high heat resistance and high specific strength.

  Conventionally, a long glass fiber reinforced polyamide resin composite material using an electric wire coating method has been known (see, for example, Non-Patent Document 1). However, according to such conventional technology, a molded product is obtained by injection molding a compound material of glass fiber and polyamide resin. In the compounding process and injection molding process, breakage of the glass fiber was remarkable, the reinforcing effect on the strength and elastic modulus of the glass fiber was lowered, and the practical performance as a structural material was unsatisfactory.

In order to obtain high-strength and high-rigidity molded products, composite materials of carbon fiber and polyamide resin have also been researched and developed. However, the carbon fiber was broken in the injection molding and extrusion molding processes, and the effect was not fully met. In order to avoid breakage of the reinforcing fiber, compression molding with small shear deformation at the time of molding was also examined. However, when the reinforcing fiber becomes longer, the fibers are entangled and the fluidity is remarkably lowered, and a large molded product or a molded product having a thin rib or boss structure is thinned and a good molded product cannot be obtained. .
To prevent fiber entanglement, fiber roving is opened into a single fiber, then impregnated with polyamide resin, pre-molded with a uniaxial tape-shaped prepreg composed of reinforcing fibers and polyamide resin, and then heat compression molded The method of doing is also disclosed (for example, refer nonpatent literature 2). However, in the case of a general polyamide resin, high rigidity and strength can be obtained in the absolutely dry state, but it easily absorbs moisture in the air. The request was not met.

  As a polyamide resin, a composite material of a polyamide resin having a low water absorption and having an aromatic ring has also been disclosed in JP-A Nos. 05-005060 (Patent Document 1) and JP-A No. 2002-234999 (Patent Document 2). However, the polyamide resin having an aromatic ring has a high melting point, and when compression molding the composite material, the material must be preheated to a high temperature, which makes preheating difficult and causes discoloration and deterioration due to oxidation. It was inappropriate for industrial production. In addition, composite materials of long-chain aliphatic polyamides having a low water absorption rate have been studied, but the original elastic modulus, strength, and heat resistance are greatly reduced, which is inappropriate for the demand as a structural material. Thus, a composite material for a structural material that is easy for industrial production and retains high physical properties under the use environment has not been found.

  However, industrially, there has been a high development demand on the market for a polyamide composite material for a structural material that has a low water absorption rate, maintains a high elastic modulus even under equilibrium moisture absorption, and has heat deformation resistance.

JP 05-005060 A JP 2002-234999 A

Composites, July, 150 (1973) SPI (Society of Plastics Industry) 30th 11-C (1975)

  The present invention has been made against the background of such prior art problems. That is, an object of the present invention is to provide a composite material composition for structural material having a high specific strength, which has a low water absorption rate, and has dramatically improved strength and rigidity in temperature and humidity under the usage environment.

As a result of intensive studies, the present inventors have found that the above problems can be solved by the following means, and have reached the present invention.
That is, this invention consists of the following structures.
[1] On the basis of 100 parts by mass of carbon long fiber (A) having an average of 10 mm or more, 80 mol% or more has an amide unit represented by (Formula 1) and (Formula 2), and a melting point is 200 to 300 ° C. A carbon long fiber reinforced polyamide composite material for compression molding, comprising 35 to 150 parts by mass of a polyamide copolymer (B).
—NH— (CH ₂ ) _j —NH—CO— (CH ₂ ) _k —CO— (Formula 1)
—NH— (CH ₂ ) _m —NH—CO—C ₆ H ₄ —CO— (Formula 2)
Here, j ≧ 8, k ≧ 7, m ≧ 8, [—C ₆ H ₄ —] represents a paraphenylene structure [2] Molar ratio of amide units represented by (Formula 1) and (Formula 2) (Formula 1): (Formula 2) = 80: 20 to 20:80 The carbon long fiber reinforced polyamide composite material for compression molding according to [1].
[3] The polyamide copolymer is 12 ≧ j ≧ 10, 12 ≧ k ≧ 8 in (Formula 1), and 12 ≧ m ≧ 8 in (Formula 2) [1] or [2] 2. A carbon long fiber reinforced polyamide composite material for compression molding as described in 1.
[4] The bending strength retention rate of a molded product that has been conditioned for 200 hours at 80 ° C. and 95% RH with respect to the bending strength of the molded product when absolutely dry is 80% or more. 3] The carbon long fiber reinforced polyamide composite material for compression molding according to any one of [3].
[5] The carbon long fiber reinforced polyamide composite material for compression molding according to any one of [1] to [4], wherein the polyamide copolymer has a melting point of 240 to 280 ° C.
[6] The carbon long fiber reinforced polyamide composite material for compression molding according to any one of [1] to [5], wherein the polyamide composite material is in a tape shape or a sheet shape.

  According to the present invention, it is possible to provide a composite material that has a low water absorption rate, a remarkably high strength and elastic modulus in a use environment, and satisfies the requirements of a structural material by an industrial manufacturing process. A molded product obtained by molding the composite composition obtained according to the present invention is used for a frame part of an automobile, a structural member of a mechanical instrument, a sports instrument, and the like. The reason why the present invention provides a composite composition capable of obtaining high strength and elastic modulus under the use environment is not yet clear, but is considered to be due to the following characteristics of the polyamide copolymer used in the present invention. . Copolymerize long-chain methyleneterephthalamide units with low water absorption, high strength and elastic modulus but high melting point, and long-chain aliphatic polyamide units with low water absorption but low elastic modulus and strength at a specific ratio Thus, the melting point could be controlled to be industrially possible. Furthermore, the long-chain methylene aromatic polyamide unit compensates for the low elastic modulus, strength, and low heat resistance of the long-chain aliphatic polyamide unit, thereby reducing the water absorption rate and suppressing the decrease in physical properties due to water absorption. In addition, it is considered that a specific composition ratio having high mechanical properties and a well-balanced composition ratio, good wettability to the carbon fiber surface, and high adhesive strength could be invented.

The present invention is described in detail below.
In the present invention, carbon long fibers or continuous fibers having a weight average fiber length of 10 mm or more, preferably 15 mm or more, and more preferably 20 mm or more are used. If the weight average fiber length is less than 10 mm, the strength as a structural material is not achieved, which is not preferable. In terms of mechanical properties, continuous fibers are preferable, but in the case of a molding method that requires fluidity in a mold during molding, a prepreg that is cut shorter is used. In such a case, the upper limit of the weight average fiber length of the carbon long fibers corresponds to the length of the prepreg, and is preferably about 50 mm.
Although it does not restrict | limit especially in a manufacturing method as carbon fiber, After processing fibers, such as a polyacrylonitrile fiber and a cellulose fiber, in air at 200-300 degreeC, it is baked at 1000-3000 degreeC or more in inert gas. Carbon fibers produced by carbonization and having a tensile strength of 20 t / cm ² or more and a tensile modulus of 200 GPa or more are preferred. Although the diameter of the single fiber used in the present invention is not particularly limited, it is preferably 3 to 25 μm, particularly preferably 4 to 15 μm, from the production line process of the composite. When the thickness is less than 3 μm, impregnation and defoaming are difficult. The carbon fiber used in the present invention is preferably treated for improving adhesion by wet oxidation with air or nitric acid, dry oxidation, heat cleaning, whiskerizing, or the like. Moreover, it is preferable that the carbon fiber used for composite material manufacture of this invention is bundled by the bundling agent which softens at 100 degrees C or less from the handleability of a work process. Although there is no restriction | limiting in particular in the number of focusing filaments, 1000-30000 filaments, Preferably 3000-25000 filaments are preferable. The carbon fiber sizing agent used in the present invention is not particularly limited, but urethane-based, epoxy-based, and maleic anhydride-modified polyolefin-based sizing agents having high adhesion to the polyamide copolymer of carbon fiber and parent phase are preferable. .

In the present invention, the melting point is 200 to 300 ° C., in which 80 mol% or more has an amide unit represented by (Formula 1) and (Formula 2) with respect to 100 parts by mass of carbon long fiber (A) having an average of 10 mm or more. The polyamide copolymer (B) is 35 to 150 parts by mass, preferably 40 to 150 parts by mass, more preferably 50 to 150 parts by mass.
—NH— (CH ₂ ) _j —NH—CO— (CH ₂ ) _k —CO— (Formula 1)
—NH— (CH ₂ ) _m —NH—CO—C ₆ H ₄ —CO— (Formula 2)
Here, j ≧ 8, k ≧ 7, m ≧ 8, and [—C ₆ H ₄ —] represents a paraphenylene structure. When the polyamide copolymer (B) is less than 35 parts by mass, the polyamide resin to the carbon fiber Impregnation is difficult, and if it exceeds 150 parts by mass, the effect of carbon fiber reinforcement becomes insufficient, and the requirement as a structural member, which is the object of the present invention, is not preferable.

In the present invention, a long-chain aliphatic polyamide having a melting point of 200 to 300 ° C., preferably 220 to 280 ° C., more preferably 230 to 280 ° C., particularly preferably 240 to 280 ° C. (formula 1 ) And a long chain methylene terephthalamide (formula 2) polyamide copolymer. When the melting point is less than 200 ° C., the heat distortion temperature is low, which is not preferable. If the temperature exceeds 300 ° C., a high temperature is required as a preheating temperature of the molding material during molding. Oxidation discoloration and deterioration occur and are not preferable.
The melting point of the polyamide copolymer depends on the copolymerization ratio of the long-chain aliphatic polyamide (formula 1) and the long-chain methylene terephthalamide (formula 2) and the number of carbon atoms of the raw material monomer. The carbon number of the diamine which is a raw material monomer of the long chain aliphatic polyamide (Formula 1) used in the present invention is 8 or more (in Formula 1, j is 8 or more), preferably 10 or more. If it is less than 8, the water absorption rate does not reach the expected value, which is not preferable. Specific examples include octamethylene diamine, nonamethylene diamine, decamethylene diamine, and dodecamethylene diamine. The carbon number of the dicarboxylic acid that is another raw material of the long-chain aliphatic polyamide (Formula 1) is 9 or more (k is 7 or more in Formula 1), preferably 10 or more. If the number of carbon atoms is less than 9, the water absorption rate does not reach the expected value, which is not preferable. Specific examples include polyamide components composed of azelaic acid (nonanedioic acid), sebacic acid (decanedioic acid), 1,11-undecanoic acid, 1,12-dodecanoic acid, 1,14-tetradecanedioic acid, and the like. It is done.
The carbon number of the diamine used in the long-chain methylene terephthalamide (Formula 2) (m in Formula 2) is 8 or more, preferably 8 to 12, more preferably 9 to 12, particularly preferably 10 to 12. If it is less than 8, the lowering effect of the moisture absorption rate is low, and the lowering effect of the melting point is small, which is not preferable. Specific examples include octamethylene diamine, nonamethylene diamine, decamethylene diamine, and dodecamethylene diamine. Nonamethylenediamine, decamethylenediamine, and dodecamethylenediamine are preferable from the viewpoint of the water absorption rate and the melting point lowering effect, and decamethylenediamine is particularly preferable because of the good balance between the moisture absorption rate and melting point lowering effect and the elastic modulus and strength retention effect.
The molar ratio [(Formula 1) :( Formula 2)] of the long-chain aliphatic polyamide component (Formula 1) and the long-chain methylene terephthalamide component (Formula 2) is preferably 80:20 to 20:80, and 70:30 -30: 70 is more preferable, and 60: 40-40: 60 is further more preferable. If the long-chain aliphatic polyamide component exceeds 80 mol%, the elastic modulus and strength decrease, which is not preferable. If it is less than 20 mol%, the melting point is high, and the condition range of the carbon fiber impregnation step and molding step is narrow, which is not preferable.

The polyamide copolymer (B) used in the present invention is less than 20 mol% so that the melting point is in the range of 200 to 300 ° C. in addition to the components represented by (Formula 1) and (Formula 2). Other monomers can be copolymerized within the range of. As a copolymerization component, ε-caprolactam or ω-laurylactam, and as a diamine component, 1,4-tetramethylenediamine, 1,6-hexamethylenediamine, m-xylylenediamine, p-xylylenediamine, p -Phenylenediamine, m-phenylenediamine and the like, and the acid components include isophthalic acid, orthophthalic acid, 2,6-naphthalenedicarboxylic acid, 4,4'-diphenyldicarboxylic acid, succinic acid, adipic acid, 1,4-cyclohexane Examples thereof include polyamide components composed of dicarboxylic acid and the like.
The molecular weight of the polyamide copolymer is not particularly limited, but the relative viscosity in a 5 g / l solution of 98% by mass sulfuric acid measured at 25 ° C. is preferably 1.8 to 3.0, more preferably 2. The range is from 0 to 2.8, and more preferably from 2.1 to 2.7. If it is less than 1.8, the strength decreases, which is not preferable. When it exceeds 3.0, the impregnation property to the carbon fiber is deteriorated, and the defoaming is poor. As a result, the strength of the composite material is decreased, which is not preferable.

The composite material of the present invention is a bent product of a molded product that has been conditioned for 200 hours at 80 ° C. and 95% RH with respect to the bending strength of the molded product that has been vacuum-dried at 100 ° C. for 160 hours (when absolutely dry). The strength is maintained at 80% or more, and high mechanical properties are maintained. If it is less than 80%, the physical property change by the use environment is large, and it is not preferable as a structural material. The strength retention of the composite material of the present invention is 80% or more because the water absorption rate is low at 80 ° C. and 95% RH, and the glass transition point of the plasticized product due to water absorption is lower than the test environment temperature. It is considered that it is held high.
More specifically, the low water absorption is considered to be due to the specific combined effect of the high hydrophobic long-chain aliphatic hydrocarbon monomer fraction and the high glass transition point being the high terephthalamide fraction. Is done.
As described above, by selecting the polyamide copolymer (B) of the present invention, the strength retention can be 80% or more, and further 85% or more.

  The effect of the present invention is particularly exerted when the composite material is in a tape form or a sheet form. It is considered that tape-shaped and sheet-shaped molded articles generally have a large surface area and are easy to absorb moisture, and that the molded article has a small section modulus and small bending rigidity, and is easily affected by deterioration in physical properties due to moisture absorption.

  Moreover, it is preferable that the polyamide copolymer used for this invention contains a crystal nucleating agent. If the crystal nucleating agent is not blended, the crystal size is increased in the molding process solidified from the molten state, the strength of the crystal interface is weak, the toughness is lowered, and brittleness is easily discarded, which is not preferable. The crystal nucleating agent used in the present invention is one or more combinations selected from talc, clay, and organic compounds of Group 1a metal of the periodic table. These crystal nucleating agents act as crystal nucleating agents when cooled and solidified from the melted state of the polyamide copolymer, promote crystal growth from a state of low supercooling, and increase the number of spherulites. Then, the size is refined. If the crystal nucleating agent is not blended, the molded product core is not crystallized except for the slow cooling during the solidification process, and the crystal does not reach the wavelength of light and becomes an almost transparent molded product. Silicates such as talc and clay are effective as crystal nucleating agents. These may be a refined natural stone or a synthesized silicate. As the crystal nucleating agent, it is presumed that the crystal grows in an epitaxy form from these surface crystals and the effect of lowering the free energy between the surface and the resin interface. The finer the surface area, the better. As an average particle diameter, 0.1-20 micrometers is preferable. In addition, organic compounds belonging to Group 1a of the periodic table also act as effective crystal nucleating agents. In particular, Na salts of higher fatty acids, K salts of higher fatty acids, and Li salts of higher fatty acids are effective. Examples of higher fatty acids include stearic acid, montanic acid, lauric acid and the like. Moreover, the ionomer copolymer obtained by saponifying the copolymer of acrylic acid, methacrylic acid, and polyolefin is illustrated.

  Although the compounding quantity of a crystal nucleating agent is not specifically limited, 0-10 mass parts with respect to 100 mass parts of polyamide copolymers, Preferably 0.01-5 mass parts is mix | blended. Examples of crystal nucleating agents include minerals such as talc and clay, sodium salts of higher fatty acids, potassium salts, dithium salts, calcium salts, zinc salts, alkali salts of ethylene-acrylic acid and alkali salts of ethylene-methacrylic acid. Is done.

  In the present invention, stamping molding may further include 0.05 to 5 parts by mass, particularly 0.1 to 2 parts by mass of the higher fatty acid periodic table group 2a metal salt with respect to 100 parts by mass of the carbon fiber. This is a preferred embodiment for improving the properties. If it is less than 0.05 parts by mass, the releasability after stamping molding is low, and a deep-drawn molded product is not preferable because it is deformed at the time of mold release and the cooling time until it can be taken out is long. Moreover, when it exceeds 5 mass parts, the external appearance of the molded article surface may be impaired, and it is not preferable. Examples of higher fatty acids include stearic acid, lauric acid, and montanic acid. Examples of periodic table group 2a include magnesium, calcium, and valium. Specific examples of the compound include magnesium stearate, calcium stearate, and calcium montanate.

  The molding method of the composite material of the present invention is a molding method suitable for stamping molding. Therefore, the mold temperature (mold surface temperature) is completely different from the usual injection molding method of 150 ° C. or less, preferably 100 ° C. or less, and surprisingly the mold temperature is 160 to 280 ° C., preferably 180 to 260. It is a preferred embodiment to mold with a metal mold at ° C. If the mold surface temperature is less than 160 ° C., the fluidity is low, and the flow ends and the ribs may be insufficiently filled. Moreover, when it exceeds 280 degreeC, the resin surface will oxidize and discoloration and deterioration will occur and it is not preferable. By using a high-temperature mold of 160 to 280 ° C. in the initial stage of filling, the characteristics of the present invention can be exhibited. By filling in a higher temperature mold, the material temperature at the time of filling or the material temperature after filling becomes higher than the crystallization temperature of the material. Since the crystallization peak temperature at which the crystallization speed becomes the fastest during the cooling process until the molded product is taken out, the surface of the molded product is sufficiently crystallized, so that a molded product with high heat distortion resistance can be obtained. Considered.

In the composite material of the present invention, in addition to the above essential components and optional components, a lubricant, an antioxidant, a flame retardant, a light-proofing agent, a weathering agent and the like are added for the purpose of improving physical properties, improving moldability, and improving durability. It can mix | blend in the range of 10 mass% or less in a composite material.
The method for producing the composite material of the present invention is not particularly limited. For example, a polyamide copolymer and a stabilizer are premixed at a predetermined ratio and supplied to a hopper of a screw type extruder whose temperature is controlled to be equal to or higher than the melting point of the polyamide copolymer. The molten resin is measured at the number of revolutions of the gear pump and supplied upstream of the impregnation extruder whose temperature is adjusted to be equal to or higher than the melting point of the resin. On the other hand, roving-like carbon fibers are expanded and supplied downstream of the impregnation extruder. Carbon fiber roving is impregnated and defoamed with resin pressure in an extruder for impregnation equipped with a slit die having a narrowed opening at the downstream end. The composite material composed of the tape-like carbon fiber and the polyamide copolymer discharged from the downstream opening is cooled and wound up. Furthermore, the tape-like composite material is cut into 10 mm or more, or the tape-like composite material is woven into a woven shape without being cut and provided for molding. In addition, a polyamide copolymer and a stabilizer are premixed at a predetermined ratio and supplied to an upstream hopper of a screw type extruder whose temperature is controlled to be equal to or higher than the melting point of the resin. A roving-like carbon fiber is supplied to the downstream exit die, and a fiber-coating speed and a resin discharge amount are adjusted to obtain a strand-like carbon fiber resin coating material having a predetermined fiber content. The strand is cooled and wound into skeins. A method of cutting the strand into 10 mm or more, or weaving it into a woven shape and providing it for molding can be raised.
After the composite material of the present invention is heated and melted by infrared rays or high frequency, it is supplied to a mold whose temperature is adjusted to 160 to 280 ° C. which is higher than the crystallization temperature of the constituting polyamide copolymer, and is shaped by compressive force. The structural part is formed by the method of demolding after cooling.

  Molded parts obtained from the composite material of the present invention include automobile frames, bumper face bar support materials, chassis shells, seat frames, suspension supports, sunroof frames, bumper beams, two-wheeled vehicle frames, farm equipment frames, OA. Used for parts that require high strength and rigidity, such as equipment frames and machine parts.

EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited to the examples.
(Measuring method)
(1) Weight average fiber length of carbon long fiber A fine piece of a composite material or a composite molded product was melted between two slide glass plates to form a film having a thickness of about 0.05 mm. Using a microscope (manufactured by KEYENCE), measure the length of the fibers where the center of gravity (the center of the length) of each fiber exists within a limited field of view at a magnification of 100 times with transmitted light, and measure 100 to 200 fibers. Thus, histograms at intervals of 0.1 mm were created. It calculated | required by the following Formula from the median (Xi) and frequency (fi) of the class.
X = ΣfiXi ² / ΣfiXi
(2) Relative viscosity According to JIS K6920-2: 2009, an Ostwald viscometer (manufactured by Asahi Seisakusho, Model 4810) is used for a 5 g / l solution of 98% sulfuric acid of a polyamide copolymer in a constant temperature water bath at 25 ° C. It was calculated from the solution falling seconds and the solvent dropping seconds.
(3) Melting point (Tm)
About 10 mg test piece was collected on an aluminum pan from the polyamide copolymer. As a differential scanning calorimeter (DSC), a Q100 DSC manufactured by TA instruments was used, and the temperature was raised at 20 ° C./min in a nitrogen flow according to ISO 11357-3, and the peak temperature of the heat flow was taken as the melting point. .

The moldability and physical properties were evaluated as follows.
(4) Moisture absorption rate Using a thermo-hygrostat (LH21-21M type, manufactured by Nagano Science Co., Ltd.) 13 bend test pieces of 100 × 12.5 × 2 mm obtained by cutting from the obtained flat plate molded product. , And left at 80 ° C. under 95% RH for 200 hours, the surface adhering water was wiped off with a tissue paper, and the respective masses were measured to obtain m1. Arbitrary seven of these test pieces were placed in a vacuum dryer (Yamato Scientific Co., Ltd., square vacuum constant temperature dryer DP43 type) whose temperature was adjusted to 100 ° C., dried for 160 hours, and then weighed. m2.
The moisture absorption rate at 80 ° C. and 95% RH was determined by the following formula.
Moisture absorption rate (%) = (m1−m2) × 100 / m2

(5) Bending characteristics Five molded articles (humidity absorption sample) left for 2 hours in a test room adjusted to 23 ° C and 50% RH after moisture absorption treatment at 80 ° C and 95% RH in (4), and moisture absorption Three-point bending tester (Orientec Co., Ltd.) compliant with ISO178 for five test pieces (dried samples) left for 2 hours in a desiccator in a test chamber whose temperature was adjusted to 23 ° C. Tensilon 4L type) was used to measure the bending strength and the bending elastic modulus at a span length of 80 mm and a crosshead speed of 1 mm / min.
(6) Deflection temperature under load For three molded products that have been subjected to moisture absorption treatment and vacuum drying treatment in (4), use a heat distortion tester manufactured by Toyo Seiki Co., Ltd. in the flatwise direction in accordance with ISO75-1, -2. The deflection temperature under load of 1.8 MPa was determined.
(7) Prepreg impregnation property The prepreg impregnation property was judged from the state of the fiber on the surface of the molded product.
○: Area ratio of the raised part of the fiber is less than 5%, X: Area ratio of the raised part of the fiber is 5% or more

Examples 1-5
The polyamide copolymer shown in Table 1 was put into a hopper of a screw type extruder whose temperature was adjusted to the melting point + about 30 ° C. After plasticization in the extruder, the molten resin was supplied from the die head to the impregnation table. On the other hand, the carbon fiber roving shown in Table 1 is expanded and opened, led to an impregnation die connected to the die head of the extruder, and the take-up roller is driven at a speed at which the carbon fiber becomes 100 parts by mass to impregnate. Pulled out from the die. A tape-shaped prepreg impregnated and coated from a die having a width of 10 mm and a height of 0.2 mm was shaped by a take-up roller and solidified, and then wound on a basket.
The tape-shaped prepregs were arranged so as to form 10 layers between bars having an interval of 300 mm and a width of 150 mm, and wound up. This was placed between 200 × 200 mm face plates of a heat press whose temperature was adjusted to about 30 ° C. higher than the melting point, and pressurized for about 5 MPa for 5 minutes. After that, it was taken out together with the face plate, moved between cooling plates provided with a water cooling circuit, and cooled to 50 ° C. or lower in a state where the pressure was kept at 5 MPa. Thereafter, the face plate was opened to obtain a carbon fiber reinforced polyamide copolymer molded plate having a thickness of about 2 mm in which carbon fibers were uniaxially oriented. A test piece of 100 mm × 12.5 mm was cut from the molded plate in the fiber axis direction. About the obtained test piece, the water absorption rate, the bending characteristic, and the deflection temperature under load were evaluated.
The example product has a retention rate of 80% or more when absorbing moisture.

Example 6
In the same manner as in Example 1, the tape was impregnated with resin, pulled out from the impregnation die, shaped by a take-off roller and solidified, and the strip-shaped prepreg obtained by cutting into 35 mm was formed into a strip-shaped prepreg tape of 200 mm × 200 mm. The plate was randomly distributed in a flat plate mold. The mold was heated to 280 ° C., compressed, held for 3 minutes, and then cooled to 150 ° C. to obtain a prepreg sheet in which carbon fibers were randomly oriented. This prepreg sheet is preheated to 280 ° C. with a far-infrared heater, attached to a compression molding machine (manufactured by Shinfuji Metal Industry Co., Ltd., 50 t), and supplied to a mold having a 210 mm × 210 mm cavity whose temperature is adjusted to 180 ° C. Then, compression molding was performed at 30 MPa for 3 minutes to obtain a flat molded product having a thickness of about 2 mm.
A test piece of 100 mm × 12.5 mm was cut from the center of the flat molded product obtained by compression molding. About the obtained test piece, the moisture absorption rate, the bending characteristic, and the deflection temperature under load were evaluated in the same manner as in Example 1.
In Example 6 in which the fibers were randomly oriented, there was almost no anisotropy and a high bending strength of 410 MPa was shown even after moisture absorption.

Comparative Examples 1-3
A prepreg tape was prepared in the same manner as in Example 1 except that the polyamide copolymer was changed as shown in Table 2, and then a molded plate was formed and a test piece was cut in the fiber axis direction. The physical properties of the obtained test pieces were evaluated in the same manner as in the examples. The obtained test data is shown in Table 2 together.

Comparative Example 4
Except that the length of the strip-shaped prepreg was set to 6.5 mm, the test piece obtained by forming a randomly oriented molded plate and cutting it from the flat plate was evaluated in the same manner as in Example 6. It is shown in Table 2.
Compared with Example 6, the reinforcing effect of the fiber is not sufficient, and the bending strength is 335 MPa, which is insufficient as a structural material even in a dry state.

Raw material and symbol PA1: decamethylene terephthalamide / amide 1010 = 60/40 (molar ratio) copolymer (Toyobo prototype, Tm 255 ° C., relative viscosity 2.5)
PA2: decamethylene terephthalamide / amide 1010 = 20/80 (molar ratio) copolymer (Toyobo prototype, Tm 227 ° C., relative viscosity 2.5)
PA3: decamethylene terephthalamide / amide 1010 = 80/20 (molar ratio) copolymer (Toyobo prototype, Tm 295 ° C., relative viscosity 2.4)
PA4: Nonamethylene terephthalamide / amide 1010 = 60/40 (molar ratio) copolymer (Toyobo prototype, Tm 248 ° C., relative viscosity 2.5)
PA5: Polyamide 6 T802 (manufactured by Toyobo, relative viscosity 2.5)
PA6: polyamide 1010 (Toyobo prototype, Tm 200 ° C., relative viscosity 2.5)
PA7: Polydecamethylene terephthalamide (Toyobo prototype, Tm 305 ° C, relative viscosity 2.5)
Carbon fiber: Toho Tenax IMS40 manufactured by Teijin Ltd. (single fiber diameter 6.4 μm, 6000 filaments)
MW5000: Talc (manufactured by Hayashi Kasei Co., Ltd., micron white) average particle size 4 μm
CAV102: Montanic acid calcium salt (manufactured by Clariant)

  The polyamide Toyobo prototype was polymerized by appropriately selecting raw material monomers based on the method described in JP 2010-150445 A. Amide 1010 is an amide unit composed of decamethylenediamine and sebacic acid.

  Examples 1 to 5 in which fibers are uniaxially oriented maintain high strength and heat resistance as a structural material, have a low moisture absorption rate, and have a high strength retention rate during moisture absorption.

  According to the present invention, it is possible to obtain a stamping molded product having a low moisture absorption rate, a high elastic modulus and bending strength after equilibrium moisture absorption, and excellent heat resistance, and it is possible to make a structural member and a housing resin, and to reduce the weight. It is expected to greatly contribute to the industry from the aspect of energy saving.

Claims (3)

To the average 10mm or more carbon long fibers (A) 100 parts by mass of, possess more than 80 mol% (Formula 1) and amide units represented by formula (2), (Equation 1), (Equation 2) The molar ratio of the amide units represented by the formula is (Formula 1) :( Formula 2) = 80: 20 to 20:80. In (Formula 1), 12 ≧ j ≧ 10, 12 ≧ k ≧ 8, (Formula 1) Ru 12 ≧ m ≧ 8 der in 2), melting point containing polyamide copolymer 200 to 300 [° C. (B) 35 to 150 parts by weight, relative to the bending strength of the molded article at the time of absolute dry, 80 ° C. 95% retention of flexural strength of the molded article was conditioned at 200 hours tone RH is, long carbon fiber reinforced polyamide composite material for compression molding, characterized in der Rukoto 80% or more.
—NH— (CH ₂ ) _j —NH—CO— (CH ₂ ) _k —CO— (Formula 1)
—NH— (CH ₂ ) _m —NH—CO—C ₆ H ₄ —CO— (Formula 2)
Here , [ —C ₆ H ₄ —] represents a paraphenylene structure. 2. The carbon long fiber reinforced polyamide composite material for compression molding according to claim 1, wherein the polyamide copolymer has a melting point of 240 to 280 ° C. 3. 3. The carbon long fiber reinforced polyamide composite material for compression molding according to claim 1 or 2 , wherein the polyamide composite material is in the form of a tape or a sheet.