JP2006348233A - Fine polyamideimide fiber- and/or fine polyimide fiber-reinforced resin composition - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fiber-reinforced resin composition which is obtained by dispersing and mixing a fine polyamideimide fiber and/or fine polyimide fiber with a thermoplastic resin or uncured thermosetting resin, and which has excellent affinity with various resins, has a uniform dispersion state of the fiber, has excellent in mechanical properties such as toughness, flexibility and strength even when the content of the fiber is small, has good moldability and which gives a molded article having good external appearance after the molding. <P>SOLUTION: Notably improved mechanical properties and moldability of the composition are achieved, even when the content of the fiber is small, by the mixing and kneading of a markedly fine polyamideimide fiber and/or polyimide fiber as a principal component fiber, in the above fiber-reinforced materials using various resins. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a fiber reinforced resin composition capable of giving a molded article excellent in mechanical properties such as toughness, flexibility and strength, and moldability. More specifically, it is possible to uniformly disperse various thermoplastic resins or uncured thermosetting resins as a matrix, so that fine polyamideimide fibers and / or fine fibers that can give a molded article with good moldability and appearance after molding. The present invention relates to a polyimide fiber-containing reinforced resin composition.

  Conventionally, as means for improving the mechanical properties of various resin materials, there is a fiber reinforced resin using a fibrous filler such as glass fiber, synthetic fiber, or carbon fiber as a reinforcing material. In particular, fiber reinforced plastic called FRP is made by a method in which a glass fiber fabric, a carbon fiber fabric, or the like is used as a prepreg and impregnated with a resin. Although these materials are lighter than metals of the same volume, they are excellent in strength and rigidity, and are widely used as structural materials for aircraft, space equipment applications, ships, vehicles and the like.

  However, these fiber woven reinforced resins have high mechanical anisotropy due to the fiber direction and are generally strong against forces in the horizontal direction against the fabric, but against tensile forces in the vertical direction. There is a problem that it is weak and easily peels off. As a countermeasure against this problem, methods such as connecting the layers of fiber fabrics with high-strength fibers such as aromatic amides have also been attempted, but there are problems such as stress concentration in the vicinity of the interlayer connecting yarn and breakage progressing. is there. Furthermore, the molding is generally carried out by stacking fiber fabrics, impregnating with resin, pressing according to the mold, and finally completely curing, or by sequentially stacking resin and fiber fabric on the mold. . These methods are not only difficult to mass-produce efficiently, but also have problems such as variations in strength between products.

  On the other hand, as another form of the fiber reinforced resin, there is a method in which glass fiber or carbon fiber is previously kneaded into a resin to be pelletized, and this is press molded or injection molded. In this method, a molding method suitable for mass production can be applied, and a fiber reinforced resin molded product by this method has already been proposed.

  These fiber reinforced resin molded products can be broadly classified into short fiber reinforced types and long fiber reinforced resin reinforced types. The mechanical strength of such a fiber reinforced resin molded product is greatly influenced by the affinity between the resin and the fiber reinforcing material when the resin and the fiber reinforcing material are mixed to prepare the fiber reinforced resin molded product. In other words, in the case of a familiar combination of resin and fiber reinforcement, the mechanical strength of the fiber reinforced resin molded product is improved by the effect that the fiber reinforcement is uniformly dispersed in the resin and strongly bonded throughout the interface with the resin. It can be improved. In particular, in the case of a long fiber reinforced resin molded product, the mechanical strength increases along the orientation direction of the long fibers in the molded product. Therefore, by aligning (aligning) the orientation directions of many blended long fibers. A marked improvement in strength is desired. However, on the other hand, since the fiber reinforcing material tends to stay in a state close to the bundling body (roving or the like), local shortage of mechanical strength (in a thin portion or the like) of the long fiber reinforced resin molded product often occurs. The problem remains.

  On the other hand, in the short fiber reinforced resin molded product, the fiber reinforcing material is easily dispersed throughout the resin due to the effect that the blended fibers are short. Therefore, the uniform mechanical strength of each part can be improved by the short fibers entering the thin part (fine part) of the molded product. In addition, since the fibers spread randomly in the resin, there is an advantage that anisotropy is hardly generated. However, in the method of blending short fibers of about 3 mm with a matrix resin and kneading with a kneader or the like, the fiber breakage during kneading reduces the average fiber length in the molded product to about 0.3 mm, and there is little entanglement. Has not been fully demonstrated, and it has not been able to have satisfactory performance for applications that require high impact strength. Therefore, in these methods, it is necessary to mix at least 10%, usually 20% or more of fibers in order to improve mechanical properties. Usually, the glass fiber or carbon fiber used has a diameter of several μm or more, and as a result, the fiber tends to appear as irregularities on the surface after molding, and there is a problem that the appearance is poor.

  However, in recent years, ultrafine carbon fibers having a diameter of several nanometers to several tens of nanometers called carbon nanotubes have been used for these applications. This is because the smaller the fiber diameter is, the larger the surface area becomes, and it is easy to exert the effect even with a small amount of addition, a high reinforcing effect can be expected with high-strength carbon nanotubes, and the appearance after molding is finished cleanly. . In the past, the addition of a small amount of carbon nanotubes has been shown to be effective in improving mechanical strength while maintaining a good appearance. However, carbon nanotubes generally have a cylindrical shape with a continuous six-membered carbon ring, and the surface thereof is extremely smooth. It is known that the surface energy is extremely low, so that it is not well-familiar with the resin. For this reason, peeling at the interface is likely to occur, and the expected effect is not achieved. In addition, because of the low surface energy, carbon nanotubes cannot be easily dispersed even if they are kneaded directly into a resin, and are combined together. For this reason, the carbon nanotube surface is specially modified, or a master pellet containing carbon nanotubes at a high concentration is prepared in advance and mixed while diluting in stages (for example, patents). Reference 1). Furthermore, it has been pointed out as a problem that the use of the molded product is limited because the appearance of the molded product is black.

Accordingly, a fiber reinforced resin composition in which nanofibers are kneaded with a low degree of coloring of the fiber itself, a fine fiber diameter, good compatibility with the resin, easy and uniform dispersion, and sufficient strength itself. Is desired.
JP 2003-286350 A

  While fiber reinforced compositions of various resins have been used, the present inventors have made intensive studies in view of the current situation where it is difficult to satisfy all the demands with the conventional technology and still cannot obtain sufficient effects. As a result, a new fiber-reinforced resin composition has been completed.

  That is, the problem of the present invention is that since the dispersion state is uniform, the mechanical properties such as toughness and strength are excellent despite the low content, the moldability is good, the coloring degree after molding is low, and the appearance An object of the present invention is to provide a fiber-reinforced resin composition that can improve the quality of the resin.

  The above problem is that kneading fine polyamideimide fiber and / or fine polyimide fiber of 0.01 μm or more and less than 2 μm made using a special technique with various thermoplastic resins or uncured thermosetting resins. It can be achieved.

  In the present invention, fine polyamideimide fibers and / or fine polyimide fibers having a diameter of 0.01 μm or more and less than 2 μm are converted into various thermoplastic resins or uncured thermosetting resins in the range of 0.1 mass% or more and less than 50 mass%. Knead. In the fiber reinforced resin composition of the present invention, extremely fine polyamideimide fibers and / or polyimide fibers are separated into individual units by mechanical shearing force during kneading and are uniformly dispersed in the matrix. Is a feature.

  In this fine polyamideimide fiber and / or fine polyimide fiber reinforced composite resin composition, a thermoplastic resin or an uncured thermosetting general resin can be used as the matrix resin. The fine fiber content exhibiting sufficient mechanical properties can be set in a range of 0.1% by mass or more and less than 50% by mass according to desired properties. In particular, in the present invention, sufficient mechanical properties can be exhibited even with a very small fiber content of 1% or less, and the improvement of flexibility and toughness is particularly good.

  The present invention is a resin in which fine polyamideimide fibers and / or fine polyimide fibers are dispersed and mixed in various thermoplastic resins or uncured thermosetting resins, and the dispersion state of the fibers because of good affinity with various resins. A molded product with excellent strength, impact resistance, toughness, flexibility, etc. despite the fact that it is uniform and efficient, does not cause defects such as appearance, and the fiber content is small. A fiber reinforced resin composition is provided. By using the fiber reinforced resin composition, a stable molding process is possible, and a fiber reinforced resin molded article having uniform and stable mechanical properties can be obtained.

  The fine polyamideimide fiber and fine polyimide fiber used in the present invention are made from a polyamideimide resin and a polyimide resin, respectively. The polyamide-imide resin and the polyimide resin do not need to be special, and the manufacturing method is not particularly limited. Although it is obtained by a generally performed method, it will be exemplified and explained below.

  Polyamideimide resin is prepared by a method in which an equimolar amount of aromatic tricarboxylic acid monoanhydride and aromatic diamine is subjected to polycondensation / imidation reaction at high temperature in the presence of a dehydration catalyst in an organic polar solvent, A method in which an equimolar amount of an aromatic tricarboxylic anhydride monochloride represented by chloride and an aromatic diamine is subjected to a polycondensation / imidization reaction at low temperature in an organic polar solvent, or an aromatic tricarboxylic acid monoanhydride and an aromatic It is produced by a method such as a polycondensation / imidization reaction with diisocyanate at high temperature in an aprotic organic solvent such as dimethylacetamide, dimethylformamide, dimethylsulfoxide, N-methyl-2-pyrrolidone and the like. These organic solvents can be used in combination with toluene, xylene, acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, dioxane, ethylene glycol dimethyl ether, tetrahydrofuran, ethyl acetate, γ-butyl lactone, and the like.

  In either case, polymerization is carried out while increasing the amide bond to increase the molecular weight. On the other hand, the amidic acid moiety is also subjected to intramolecular imidization reaction at the same time or later as the growth, and the target polyamideimide is obtained. It is obtained by dissolving in. Therefore, the polyamideimide resin referred to in the present invention basically has the structure of an amideimide, but may contain a certain degree of unimidated amic acid moiety.

  Here, as the aromatic tricarboxylic acid monoanhydride, trimellitic acid monoanhydride is desirable, but a part thereof can be replaced with another polybasic acid or its anhydride. For example, tetracarboxylic acids such as pyromellitic acid, biphenyltetracarboxylic acid, biphenylsulfonetetracarboxylic acid, benzophenonetetracarboxylic acid, biphenylethertetracarboxylic acid, ethylene glycol bistrimellitate, propylene glycol bistrimellitate and their anhydrides, Aliphatic dicarboxylic acids such as oxalic acid, adipic acid, malonic acid, sebacic acid, azelaic acid, dodecanedicarboxylic acid, dicarboxypolybutadiene, dicarboxypoly (acrylonitrile-butadiene), dicarboxypoly (styrene-butadiene), 1,4 Cyclohexanedicarboxylic acid, 1,3-cyclohexanedicarboxylic acid, 4,4-dicyclohexylmethanedicarboxylic acid, dimer acid and other alicyclic dicarboxylic acids, terephthalic acid, isophthalic acid Acid, diphenyl sulfone dicarboxylic acid, diphenylether dicarboxylic acid, and aromatic dicarboxylic acids such as naphthalene dicarboxylic acid.

  In addition, a part of the trimellitic acid compound can be replaced with glycol. Examples of glycols include alkylene glycols such as ethylene glycol, propylene glycol, tetramethylene glycol, neopentyl glycol, and hexanediol, polyalkylene glycols such as polyethylene glycol, polypropylene glycol, and polytetramethylene glycol, and one or two of the above dicarboxylic acids. The polyester of the terminal hydroxyl group etc. which are synthesize | combined from the above and 1 type, or 2 or more types of the said glycol are mentioned.

  Aromatic diamines include 3,3'-diaminobenzophenone, P-phenylenediamine, 4,4'-diaminodiphenyl, 4,4'-diaminodiphenylmethane, 4,4'-diaminodiphenyl ether, Bis [4- {3- (4-aminophenoxy) benzoyl} phenyl] ether, 4,4'-bis (3-aminophenoxy) biphenyl, bis [4- (3-aminophenoxy) phenyl] sulfone, 2,2'-bis [4- (3-Aminophenoxy) phenyl] propane and the like. Here, when the aromatic diamine component has an amide bond in the main chain (for example, the 4,4′-diaminobenzanilide), an aromatic tetracarboxylic dianhydride can be combined as the acid component.

  Examples of the aromatic diisocyanate include those in which two amino groups of the aromatic diamine exemplified above are substituted with isocyanate groups.

  On the other hand, a polyimide resin is generally obtained by reacting and polymerizing a tetracarboxylic acid derivative and a primary diamine to obtain a polyimide precursor, and ring-closing imidization to obtain a polyimide. Specific examples of the tetracarboxylic acid derivative used for obtaining the polyimide resin of the present invention or a precursor thereof include pyromellitic acid, 2,3,6,7-naphthalenetetracarboxylic acid, 1,2,5, 6-naphthalenetetracarboxylic acid, 1,4,5,8-naphthalenetetracarboxylic acid, 2,3,6,7-anthracenetetracarboxylic acid, 1,2,5,6-anthracenetetracarboxylic acid, 3,3 ′ , 4,4'-biphenyltetracarboxylic acid, 2,3,3 ', 4'-biphenyltetracarboxylic acid, bis (3,4-dicarboxyphenyl) ether, 3,3', 4,4'-benzophenone tetra Carboxylic acid, bis (3,4-dicarboxyphenyl) sulfone, bis (3,4-dicarboxyphenyl) methane, 2,2-bis (3,4-dicarboxyphenyl) ) Propane, 1,1,1,3,3,3-hexafluoro-2,2-bis (3,4-dicarboxyphenyl) propane, bis (3,4-dicarboxyphenyl) dimethylsilane, bis (3 , 4-dicarboxyphenyl) diphenylsilane, 2,3,4,5-pyridinetetracarboxylic acid, aromatic tetracarboxylic acids such as 2,6-bis (3,4-dicarboxyphenyl) pyridine and their dianhydrides As well as dicarboxylic acid diacid halides, 1,2,3,4-cyclobutanetetracarboxylic acid, 1,2,3,4-cyclopentanetetracarboxylic acid, 1,2,4,5-cyclohexanetetracarboxylic acid , 2,3,5-tricarboxycyclopentylacetic acid, 3,4-dicarboxy-1,2,3,4-tetrahydro-1-naphthalene succinic acid Tetracarboxylic acids and their dianhydrides and their dicarboxylic acid diacid halides, aliphatic tetracarboxylic acids such as 1,2,3,4-butanetetracarboxylic acid and their dianhydrides and their dicarboxylic acids And diacid halides.

  Specific examples of the diamine used to obtain the polyimide resin are p-phenylenediamine, m-phenylenediamine, 2,5-diaminotoluene, 2,6-diaminotoluene, 4,4'-diaminobiphenyl. 3,3'-dimethyl-4,4'-diaminobiphenyl, 3,3'-dimethoxy-4,4'-diaminobiphenyl, diaminodiphenylmethane, 4,4'-diaminodiniphenyl ether, 2,2-diaminodiphenyl Propane, bis (3,5-diethyl-4-aminophenyl) methane, diaminodiphenylsulfone, diaminobenzophenone, diaminonaphthalene, 1,4-bis (4-aminophenoxy) benzene, 1,4-bis (4-aminophenyl) ) Benzene, 9,10-bis (4-aminophenyl) anthracene, 1,3-bis (4-aminophenoxy) benzene, 4,4'-bis (4-aminophenoxy) diphenyl sulfone, 2,2-bis [4- (4-aminophenoxy) phenyl] propane, 2,2- Aromatic diamines such as bis (4-aminophenyl) hexafluoropropane and 2,2-bis [4- (4-aminophenoxy) phenyl] hexafluoropropane, bis (4-aminocyclohexyl) methane, bis (4-amino -3-Cyclocyclohexyl) alicyclic diamines such as methane and aliphatic diamines such as tetramethylene diamine and hexamethylene diamine, and further diaminosiloxanes.

  A tetracarboxylic acid derivative and a diamine are reacted and polymerized to form a polyimide precursor. As the tetracarboxylic acid derivative used in this case, it is common to use a tetracarboxylic dianhydride. The molar ratio of tetracarboxylic dianhydride and diamine is preferably 0.8 to 1.2. Similar to the normal polycondensation reaction, the closer the molar ratio is to 1, the greater the degree of polymerization of the polymer produced. The method of reacting and polymerizing tetracarboxylic dianhydride and diamine is not particularly limited, and generally N-methyl-2-pyrrolidone, N, N-dimethylacetamide, N, N-dimethylformamide, etc. A diamine is dissolved in an organic polar solvent, and tetracarboxylic dianhydride is added to the solution and reacted to synthesize a polyimide precursor. The reaction temperature in that case can select -20 degreeC to 150 degreeC, Preferably arbitrary temperature of -5 degreeC to 100 degreeC can be selected.

  The control of the number average molecular weight of the polyamideimide resin and the polyimide resin produced as described above can be generally performed by changing the reaction time, but generally the range of 10,000 to 100,000, preferably 20,000 to 80,000 is appropriate.

  Next, it is necessary to obtain fine polyamideimide fibers having a diameter of 0.01 μm or more and less than 2 μm from the polyamideimide resin and the polyimide resin. This method does not have any special restrictions, and any method that enables miniaturization may be used. Here, as an example, a wet spinning method is shown as a specific example for easily obtaining fine polyamideimide fiber and fine polyimide fiber.

  First, for fine polyamideimide fibers, a mixture obtained by dissolving a polyamideimide resin and at least one fiber-forming polymer compound in a common organic solvent is used as a spinning stock solution, and this is used for the fiber-forming polymer compound. After wet spinning through the pores in a bath having a solidifying ability, easy-divided polyamideimide fibers are obtained by a method of drying and heat treatment, and only the fiber-shaped polymer compound is selectively selected from the easily-divided fibers. By dissolving, a fine polyamideimide fiber can be obtained.

  On the other hand, for fine polyimide fibers, it is desirable that the polyimide resin that has already been imidized can be dissolved in a solvent such as N-methyl-2-pyrrolidone, and the polyimide resin itself can be used as one of the spinning dope.

  However, polyimide resins generally become insoluble in organic solvents after imidation, although depending on the molecular weight. In this case, a method of imparting solubility to an organic solvent by a method such as siloxane modification can be used. Specifically, this is a technique of forming a copolymer in which diaminosilane or the like is introduced into the polyimide molecular main chain.

  Moreover, what melt | dissolved the polyimide precursor in the organic solvent in the organic solvent common with a fiber-forming high molecular compound may be used as a spinning dope.

  Examples of the fiber-type polymer compound include polyacrylonitrile, polyvinyl butyral, cellulose triacetate, cellulose diacetate, polyvinyl chloride, polyvinylidene chloride, polyvinyl acetate, polyamide, polyvinylidene fluoride and copolymers thereof, or a mixture thereof. Raised.

  For example, when cellulose triacetate or cellulose diacetate is used, it is preferably dissolved in methylene chloride or N-methyl-2-pyrrolidone. When polyacrylonitrile is used, it can be dissolved in dimethylformamide, dimethylacetamide, dimethylsulfoxide, N-methyl-2-pyrrolidone and the like. For other fiber-type performance polymer compounds, a solvent may be appropriately selected, and two or more kinds of mixed solvents may be used.

  Subsequently, a method for preparing a spinning dope from a polyamideimide resin and a polyimide resin and a polymer compound used in the present invention will be described. In this case, a mixture obtained by dissolving the polyamideimide resin or polyimide resin and the fiber-forming polymer compound in an organic solvent capable of dissolving both is used as a spinning dope. The ratio of the polyamideimide resin or polyimide resin and the fiber-forming polymer compound in the easily splittable polyamideimide fiber or polyimide fiber produced by spinning this mixed solution depends on the purpose of use: polymer compound: polyamideimide resin or Polyimide resin can be selected from 75:25 to 25:75. In order to obtain fine polyamideimide fiber and polyimide fiber from easily splittable polyamideimide fiber and easily splittable polyimide fiber, dissolution treatment such as soaking in a solvent that selectively dissolves only the fiber component polymer compound of sea component Is desirable. For example, acetone is preferable when the fibrous polymer compound used is cellulose diacetate, and methylene chloride is preferable when cellulose triacetate is used. In the case of polyacrylonitrile, fine polyamideimide fibers and fine polyimide fibers can be easily obtained by a method such as immersion in dioxane or a sodium thiocyanate aqueous solution.

  The diameters of the fine polyamideimide fiber and fine polyimide fiber used in the present invention need to be 0.01 μm or more and less than 2 μm in order to exhibit a desired function.

  However, the fiber length may be selected according to the desired product, and can be selected in the range from 0.05 mm to less than 100 mm. However, in the present invention which is mainly aimed at improving the mechanical strength, if the fiber length is too short, there is no effect, while if it is too long, the fibers are entangled during the kneading to form a fiber ball, and handling within the above range is important. It is. From the results verified by the inventors, 0.3 mm or more and less than 10 mm is more preferable. Apart from this, it is also possible to adopt a method in which fine polyamideimide fibers and / or fine polyimide fibers are aligned in the longitudinal direction of the resin pellets to obtain long fiber pellets containing fibers having the same length as the pellets.

  The content of the fine polyamideimide fiber and / or fine polyimide fiber in the present invention in various thermoplastic resins or uncured thermosetting resins is 0.1% by mass or more and less than 50% by mass. Preferably they are 0.5 mass% or more and less than 20 mass%. If the content of the fine polyamideimide fiber and / or fine polyimide fiber is less than 0.1%, non-uniformity occurs in the fiber dispersion in the resin, and sufficient mechanical properties cannot be improved. On the other hand, if it is 50% or more, the volume of bulky fine fibers greatly exceeds the volume of the present resin, and uniform kneading becomes difficult. Accordingly, it is preferable to use a range of 0.5% by mass or more and less than 20% by mass from the viewpoints of kneading properties and resulting mechanical properties, surface finish, and cost.

  Various thermoplastic resins or uncured thermosetting resins used for the matrix in the present invention are not particularly limited, but for example, olefinic resins such as polyethylene, polypropylene, polystyrene, and acrylics represented by polymethylmethacrylate Resins, polyester resins, polyamide resins, polyacrylonitrile resins, polyvinyl chloride resins, polyvinylidene chloride resins, polycarbonate resins, polyacetal resins, polybutadiene resins, polyvinyl alcohol resins, cellulose resins, EVA resins , Cellulose ester resins, modified polyphenylene ether resins, polytetrafluoroethylene resins, fluorine resins, polyphenylene sulfide resins, polysulfone resins, polyarylate resins, polyetherimide resins, Examples include polyether sulfone resin, polyether ketone resin, polyanil ether nitrile resin, polybenzimidazole resin, ABS resin, AS resin, protein-based polymer, and the like. A polymer may be used.

  In the present invention, it is also possible to use a so-called thermosetting resin as the matrix resin. For example, epoxy resin, phenol resin, alkyd resin, unsaturated polyester resin, polyurethane resin, silicone resin, bismaleimide resin, benzocyclobutene resin An example is this.

  The method for kneading the fine polyamideimide fiber and / or fine polyimide fiber in the resin is not particularly limited, and a known method can be used. For example, a resin pellet for matrix and polyamideimide fiber and / or fine polyimide fiber can be dry blended and a general heat kneading apparatus can be used. Examples of the kneading apparatus include a normal biaxial kneader, an extruder type kneader, a mixing roll, a Banbury mixer, and a high-speed biaxial continuous mixer. A method of forming a strand by these methods and then cutting and pelletizing again is used. The hot melt kneading temperature is not particularly limited as long as it is appropriately selected depending on the properties of the raw materials.

  On the other hand, when a thermosetting resin is selected as the matrix resin, if it can be assumed that curing proceeds during thermal kneading, it is dissolved in a solvent that dissolves the thermosetting resin, and then fine polyamideimide fibers and / or fine After adding and mixing the polyimide fibers in the solvent, the method of obtaining the kneaded resin by evaporating and removing the solvent, or the method of mixing the fine polyamideimide fibers and / or the fine polyimide fibers in advance during the production process of the thermosetting resin is used. be able to.

  Furthermore, even when using any of various thermoplastic resins for matrix or uncured thermosetting resin or kneading method, known additives such as plasticizers, antioxidants, ultraviolet absorbers, penetrants, if necessary, It is possible to add specific amounts of thickeners, antifungal agents, dyes, pigments, fillers and the like. Further, when a halogen-based agent such as bromine, silicone-based, or phosphorus-based agent is added as a flame retardant, a flame retardant resin can be obtained in the same manner as a normal resin.

  In addition to this, the purpose of imparting other functions and methods for further improving mechanical properties include calcium carbonate, silica, titanium oxide, barium sulfate, aluminum oxide, aluminum hydroxide, aluminum borate, potassium titanate, talc, kaolin, montmorillonite, Bentonite, mica, sepiolite, zonolite, various metal powders, carbon black, acetylene black, and the like can be added as fillers.

  Furthermore, it is also possible to add fiber materials other than fine polyamideimide fiber and / or fine polyimide fiber for the purpose of modifying mechanical strength, conductivity and the like. Examples include glass fibers, carbon fibers, inorganic fibers such as carbon nanofibers and carbon nanotubes, silicone fibers, carbon fibers, boron fibers, metal fibers such as iron and titanium, aramid fibers, polyester fibers, polyamide fibers, vinylon, etc. A wide variety of known materials such as organic synthetic fibers, natural fibers such as silk, cotton and hemp can be used.

  However, considering that the appearance intended by the present invention is kept good, these additives should be added in as small a quantity as possible.

  Although the shaping | molding method of the fine polyamideimide fiber and / or fine polyimide fiber reinforced resin composition of this invention is not specifically limited, For example, extrusion molding, injection molding, blow molding etc. can be used.

  In the present invention, a fiber having excellent mechanical properties such as toughness, flexibility and strength, good moldability and good appearance after molding by adding a small amount of fine polyamideimide fiber and / or fine polyimide fiber in the molded product. The reinforced resin composition has the following effects. That is, the fine polyamideimide fiber and fine polyimide fiber that function as reinforcing fibers can be easily dispersed up to a single fiber, so that they are uniformly dispersed in the matrix resin. Since the single fibers are extremely fine, the number of the single fibers is extremely large for the blended mass. In addition, since it is fine, it has high flexibility, and even if it is kneaded with an extruder or the like, the fiber does not break, and the reinforcing effect by entanglement is sufficiently exhibited.

  Various types of molded products can be obtained by injection molding or extrusion molding of the fiber reinforced resin composition of the present invention. Particularly, it has excellent mechanical properties such as toughness, flexibility and strength, and makes good use of good moldability and molded product appearance. For example, it can be used in electronic device parts, mobile terminal casings, automotive interior and exterior parts, home appliance parts, civil engineering and building materials, transportation members, furniture, aerospace equipment, mechanical members, and the like.

The present invention will be described in detail below with reference to examples. However, the present invention is not limited to these examples, and can be implemented with modifications within a range that can meet the gist of the present invention. It is.
[Adjustment of fine polyamideimide fiber]
A 5 L reaction vessel was charged with 325 g of trimellitic anhydride, 424 g of diphenylmethane-4,4′-diisocyanate and 1400 g of N-methyl-2-pyrrolidone, and the temperature was raised to 200 ° C. over about 1.5 hours with stirring. . Thereafter, stirring was continued for about 5 hours while maintaining 200 ° C. to obtain a viscous polyamideimide resin solution. When the number average molecular weight of this resin was determined in terms of polystyrene using GPC (gel permeation chromatography), it was about 55,000. N-methyl-2-pyrrolidone was added to the polyamideimide resin solution to adjust the solid content concentration to 15%.
Next, 150 g of cellulose diacetate having an acetylation degree of 55% and a polymerization degree of 120 was placed in 850 g of N-methyl-2-pyrrolidone and stirred at room temperature for about 1 hour, then heated to 60 ° C. and stirred for 30 minutes. The solution was confirmed to be completely dissolved, and cooled to obtain a cellulose diacetate solution (solid content 15%). This cellulose diacetate solution and the above-mentioned polyamideimide resin solution are added so that the mass ratio of solid content is cellulose diacetate: polyamideimide resin = 6: 4 and stirred with a small homogenizer to obtain a uniform slightly yellow transparent mixed liquid It was.
Next, this was extruded into an aqueous solution having an N-methyl-2-pyrrolidone concentration of 10 wt% and 25 ° C. while maintaining a constant discharge rate from a spinneret having a hole diameter of 0.1 mm and a hole number of 80. The number of rotations of the winding roller was adjusted so that the draw ratio was 2 to 3 in the coagulation bath. The immersion time in the coagulation bath was about 60 seconds.
The wound spool was air-dried at room temperature for 5 minutes while maintaining a tension state, and then dried at 250 ° C. for 20 minutes in a nitrogen atmosphere to obtain an easily split polyamideimide fiber bundle. This easily splittable polyamideimide fiber bundle was dipped in normal temperature acetone and allowed to stand for about 10 minutes. The supernatant acetone was removed, acetone was newly added, and the mixture was further allowed to stand for 10 minutes. After repeating this operation 5 times in total, when the fine fiber was confirmed with a scanning electron microscope, it was confirmed to be a fine polyamideimide fiber having a fiber diameter of 0.05 μm to 1 μm.
[Adjustment of fine polyimide fiber]
24.5 g of 4,4'-diaminodiphenylmethane and 437 ml of dry N-methyl-2-pyrrolidone are placed in a 2 L four-necked flask equipped with a thermometer, stirrer, raw material charging inlet, and nitrogen gas inlet. The solution was stirred and dissolved under a dry nitrogen stream. While maintaining the temperature of the reaction system in the range of 5 to 70 ° C., 26.9 g of pyromellitic dianhydride was added and reacted for 24 hours. The reaction mixture was then poured into a large excess of methanol to precipitate the reaction product. Thereafter, it was further washed with methanol and dried at 40 ° C. under reduced pressure for 24 hours. The molecular weight by GPC of the obtained polyimide resin precursor (polyamic acid) was 75,000. N-methyl-2-pyrrolidone was added to this polyimide resin precursor to adjust the solid content concentration to 15%. 75 g of cellulose diacetate having an acetylation degree of 55% and a polymerization degree of 120 was converted to 425 g of N-methyl-2-pyrrolidone. The mixture was stirred for about 1 hour at room temperature, then heated to 60 ° C., stirred and mixed for 30 minutes to confirm that it was completely dissolved, and cooled to obtain a cellulose diacetate solution (solid content 15%). The cellulose diacetate solution and the polyimide resin precursor solution described above are added so that the mass ratio of the solid content is cellulose diacetate: polyimide resin precursor = 6: 4, and stirred with a small homogenizer to obtain a uniform slightly yellow transparent mixed solution Got.
Next, this was extruded into an aqueous solution having an N-methyl-2-pyrrolidone concentration of 4 wt% and 25 ° C. while maintaining a constant discharge rate from a spinneret having a hole diameter of 0.1 mm and a hole number of 80. The number of rotations of the winding roller was adjusted so that the draw ratio was 2 to 3 in the coagulation bath. The immersion time in the coagulation bath was about 60 seconds.
The wound spool was air-dried at room temperature for 5 minutes while maintaining a tension state, and then dried at 180 ° C. for 5 minutes in a nitrogen atmosphere.
Subsequently, heat treatment was performed at 220 ° C. for 40 minutes in a nitrogen atmosphere to imidize to obtain an easily splittable polyimide fiber bundle. A part of this easily splittable polyimide fiber bundle was immersed in normal temperature acetone in a glass container and allowed to stand for about 10 minutes. The supernatant acetone was removed, acetone was newly added, and the mixture was allowed to stand for 10 minutes. After repeating this operation 5 times in total, when the fine fiber was confirmed with a scanning electron microscope, it was confirmed to be a fine polyimide fiber having a fiber diameter of 100 nm to 1000 nm.

Example 1
Polypropylene [MFR (230 ° C., 21.2 N) 2.0 g / 10 min, melting point 160 ° C.] 99% by mass, 1% by mass of the fine polyamideimide fiber cut to 3 mm length was dry blended with a Henschel mixer, and then biaxial A fixed amount was supplied from the upper supply port of the extruder, and the two components were extruded from a die at the tip into a strand while melt-kneading. The short fiber reinforced strand was cooled in a cooling water tank and then cut into an average length of about 10 mm with a strand cutter to produce a fine polyamideimide fiber reinforced polypropylene resin (pellet).
From the obtained pellets, a test piece for measuring physical properties (according to each JIS plastic test standard) was prepared using an injection molding machine (“JSW J200SA” manufactured by Nippon Steel Works), and an evaluation test of mechanical properties was performed. The test results are shown in Table 1.

(Example 2)
The same polypropylene as in Example 1 is charged into the extruder with a vent suction mechanism from the supply port and melt kneaded while being sucked. This melt is continuously fed into a spread impregnation die (pull forming apparatus) attached to the downstream end of the barrel of the extruder. On the other hand, while the roving (total denier 2000D) of the fine polyamideimide fiber is supplied into the spread impregnation die, the roving is run while sliding on the peripheral surface of the plurality of spread pins in the die. And the fiber was sufficiently impregnated with the molten resin. This spread-impregnated composite was extruded in the form of a strand, and when it was cooled with water in a cooling bath and cooled to room temperature, it was cut with a strand cutter (average length 10 mm) to produce a reinforced columnar body (reinforced pellet). The content of fine polyamideimide fiber in the obtained pellet was 10% by mass. A test piece for measuring physical properties (according to each JIS plastic test standard) was produced from this pellet using an injection molding machine (“JSW J200SA” manufactured by Nippon Steel Works), and an evaluation test of mechanical properties was performed. The test results are shown in Table 1.

(Example 3)
Polypropylene [MFR (230 ° C., 21.2N) 2.0 g / 10 min, melting point 160 ° C.] 99% by mass, 1% by mass of the above fine polyimide fiber cut to 3 mm length was dry blended with a Henschel mixer, and then biaxial extrusion A fixed amount was supplied from the upper supply port of the machine, and the two components were extruded into strands from a die at the tip while being melt-kneaded at 250 ° C. After the short fiber reinforced strand was cooled in a cooling water tank, it was cut into an average length of about 10 mm with a strand cutter to produce a fine polyimide fiber reinforced polypropylene resin (pellet).
From the obtained pellets, a test piece for measuring physical properties (according to each JIS plastic test standard) was prepared using an injection molding machine (“JSW J200SA” manufactured by Nippon Steel Works), and an evaluation test of mechanical properties was performed. The test results are shown in Table 1.

Example 4
84% by mass of novolak-type phenolic resin having a weight average molecular weight of 5000, 12% by mass of hexamethylenetetramine, 4% by mass of the fine polyamideimide fiber cut to 3 mm length, and a very small amount of release material, and heated at 150 ° C. by a dry roll. The molding material was adjusted by kneading. This was put into a mold and press-molded at 200 ° C. to prepare a test piece (according to JIS-K-6911), and an evaluation test of mechanical properties was performed. The test results are shown in Table 1.

(Example 5)
Commercially available bisphenol A-type polycarbonate resin “Caliber 200-13” [manufactured by Sumitomo Dow Co., Ltd.] (viscosity average molecular weight 21,500) 95% by mass and 5% by mass of the fine polyimide fiber cut to 5 mm length are dried with a Henschel mixer. After blending, a single screw extruder “MS40-32V” (manufactured by IK Corporation) was used and extruded from a die at the tip into a strand while melt kneading at a cylinder temperature of 270 ° C. After this short fiber reinforced strand was cooled in a cooling water tank, it was cut into an average length of about 8 mm with a strand cutter to produce a fine polyamideimide fiber reinforced polycarbonate resin (pellet).
From the obtained pellets, a test piece for measuring physical properties (according to each JIS plastic test standard) was prepared using an injection molding machine (“JSW J200SA” manufactured by Nippon Steel Works), and an evaluation test of mechanical properties was performed. The test results are shown in Table 1.

(Comparative Example 1)
Only polypropylene [MFR (230 ° C., 21.2 N) 2.0 g / 10 min, melting point 160 ° C.] was quantitatively supplied from the upper supply port of the twin-screw extruder in the same manner as in Example 1, and from the tip die while melting and kneading. Extruded into a strand. The resin strand was cooled in a cooling water tank and then cut into an average length of about 10 mm with a strand cutter to produce a polypropylene resin (pellet).
From the obtained pellets, a test piece for measuring physical properties (according to each JIS plastic test standard) was prepared using an injection molding machine (“JSW J200SA” manufactured by Nippon Steel Works), and an evaluation test of mechanical properties was performed. The test results are shown in Table 1.

(Comparative Example 2)
The same polypropylene as in Example 1 is charged into the extruder with a vent suction mechanism from the supply port and melt kneaded while being sucked. This melt is continuously fed into a spread impregnation die (pulling-molding device) attached to the downstream end of the barrel of the extruder. On the other hand, the glass fiber roving (single yarn diameter: 5 μm, total denier 6000D) is fed into the spread impregnation die, and the roving is caused to slide while sliding on the peripheral surface of a plurality of spread pins in the die. And the fiber was sufficiently impregnated with the molten resin. This spread-impregnated composite was extruded in the form of a strand, and when it was cooled with water in a cooling bath and cooled to room temperature, it was cut with a strand cutter (average length 10 mm) to produce a reinforced columnar body (reinforced pellet). The glass fiber content in the obtained pellets was 40% by mass. A test piece for measuring physical properties (according to each JIS plastic test standard) was prepared from this pellet using an injection molding machine (“JSWJ 200SA” manufactured by Nippon Steel Works), and an evaluation test of mechanical properties was performed. The test results are shown in Table 1.

(Comparative Example 3)
A novolac type phenolic resin having a weight average molecular weight of 5,000, 88% by mass, 12% by mass of hexamethylenetetramine, and a very small amount of a release agent were blended, and a molding material was prepared by heating and kneading at 150 ° C. with a dry roll. This was put into a mold and press-molded at 200 ° C. to prepare a test piece (according to JIS-K-6911), and an evaluation test of mechanical properties was performed. The test results are shown in Table 1.

(Comparative Example 4)
Only a commercially available bisphenol A type polycarbonate resin “Caliber 200-13” [manufactured by Sumitomo Dow Co., Ltd.] (viscosity average molecular weight 21,500) is used as a single screw extruder “MS40-32V” [manufactured by IK Co., Ltd. Was extruded from the die at the tip into a strand while melt-kneading at a cylinder temperature of 270 ° C. The strand was cooled in a cooling water tank and then cut to an average length of about 8 mm with a strand cutter to produce a polycarbonate resin (pellet).
From the obtained pellets, a test piece for measuring physical properties (according to each JIS plastic test standard) was prepared using an injection molding machine (“JSW J200SA” manufactured by Nippon Steel Works), and an evaluation test of mechanical properties was performed. The test results are shown in Table 1.

From the above results, comparison between the resin molded product kneaded with the fine polyamideimide fiber or fine polyimide fiber of the present invention and the resin-only molded product, Example 1, Comparative Example 1 or Example 3, and Comparative Example 1 or Example 5 In Comparative Example 4, the improvement in flexibility can be confirmed by adding fine polyamideimide fiber or fine polyimide fiber. This is a proof that flexibility, toughness and impact resistance can be greatly improved with the addition of a few fine fibers.

  Example 2 and Comparative Example 2 are comparisons when reinforced with fine polyamideimide fibers and glass fibers of normal thickness as examples of long fiber reinforced resins. Even in Comparative Example 2, although the flexural modulus, flexural strength, strength tensile strength, and Izod impact strength are improved by the addition of glass fiber, the amount of flexure and tensile elongation are reduced, and the flexibility and toughness are reduced. Represents that. Moreover, when glass fibers were mixed at a high mixing rate of 40% by mass, irregularities due to the fiber shape appeared on the appearance. On the other hand, in Example 2, the blending strength of fine polyamideimide fiber was 10%, the bending strength, the strength tensile strength, and the Izod impact strength were higher than those of Comparative Example 2, respectively, and also had flexibility and toughness. It shows that the characteristics are balanced.

  In addition, the comparison between Example 4 and Comparative Example 3 shows that the present invention is effective even in a thermosetting resin that is usually difficult to improve flexibility, toughness, and impact resistance.

Claims (2)

  A fiber reinforced resin composition comprising a fine polyamideimide fiber and / or a fine polyimide fiber having a diameter of 0.01 μm or more and less than 2 μm dispersed and mixed as a constituent fiber in a thermoplastic resin or an uncured thermosetting resin .   The fiber-reinforced resin composition according to claim 1, comprising fine polyamideimide fiber and fine polyimide fiber in a range of 0.1 mass% or more and less than 50 mass%.