Polyether nitrile and polyether nitrile-containing carbon fiber composite material

Abstract

Provided is a polyether nitrile which has N repeating units represented by formula (I) and M repeating units represented by formula (II), wherein: N and M are integers satisfying the relational expression 0<(N / (N+M))≤1.00; and the weight loss rate is 5% or less as determined by being held in the air at a temperature that is higher than the melting point thereof by 30°C for 30 minutes in thermogravimetric analysis (TG). Also provided is a polyether nitrile-containing carbon fiber composite material which contains the polyether nitrile and carbon fibers.

Description

Polyethernitrile and polyethernitrile-containing carbon fiber composites

[0001] The present invention relates to polyethernitriles and polyethernitrile-containing carbon fiber composites.

[0002] Polyethernitrile is a type of super engineering plastic with advanced properties, including excellent thermal stability, chemical resistance, and flame retardancy, as well as excellent mechanical properties such as wear resistance and friction resistance. To enhance the mechanical properties of polyethernitrile, it can be used as a composite material with carbon fiber. Patent Document 1 discloses a polyethernitrile-containing carbon fiber composite.

[0003] Japanese Unexamined Patent Publication No. 4-57973

[0004] In recent years, carbon fiber composites have been required to have higher thermal stability due to the increasingly sophisticated properties required of materials.

[0005] However, the polyethernitrile-containing carbon fiber composite material described in Patent Document 1 had insufficient thermal stability. Therefore, in view of the problems of the prior art, an object of the present invention is to provide a polyethernitrile having excellent thermal stability. Another object of the present invention is to provide a polyethernitrile-containing carbon fiber composite material suitable for mobility components, structural components, and other industrial components.

[0006] The inventors of the present invention conducted extensive research to solve the above problems and discovered that a molded article having excellent thermal stability, mechanical properties, and chemical resistance can be obtained by using a polyethernitrile-containing carbon fiber composite material using a polyethernitrile that satisfies specific conditions, thereby completing the present invention. That is, the present invention has the following features: (1) A polyethernitrile having N repeating units represented by formula (I) and M repeating units represented by formula (II), where N and M are integers satisfying the relationship 0<[N / (N+M)]≦1.00, and which exhibits a weight loss of 5% or less when maintained at a temperature above the melting point +30°C for 30 minutes in air in thermogravimetric analysis (TG):

[0007]

[0008] In the formula, Ar １ and Ar ２ each have one different type of skeleton selected from units represented by the following formula (a) to formula (f); R is any organic group selected from a linear organic group having 1 to 6 carbon atoms, a branched organic group having 3 to 6 carbon atoms, and a cyclic organic group having 3 to 6 carbon atoms; R may contain one or more atoms selected from an oxygen atom, a nitrogen atom, and a sulfur atom; a represents the number of substituents R; a in formulas (a), (b), (c), (e), and (f) is an integer of 0 to 4, and a in formulas (I), (II), and (d) is an integer of 0 to 3; when there are multiple R, R may be the same or different from each other;

[0009]

[0010] In the above formula (f), Y is a group selected from the following units; X is any one of a hydrogen atom, a methyl group, and a trifluoromethyl group.

[0011]

[0012] (2) A polyethernitrile-containing carbon fiber composite material comprising the polyethernitrile according to (1) and carbon fiber, wherein the polyethernitrile-containing carbon fiber composite material has a weight loss rate of 5% or less when held in air at a temperature 30°C above the melting point of the polyethernitrile for 30 minutes in thermogravimetric analysis (TG), and the polyethernitrile content is 20 to 85% by weight. １ is a skeleton represented by the formula (a) or the formula (e), and Ar ２ is one type of skeleton selected from the units represented by the formulas (a) to (f), and Ar １(4) The polyethernitrile-containing carbon fiber composite according to (2), wherein N and M are integers satisfying the relationship 0.80≦[N / (N+M)]<1.00. (5) The polyethernitrile-containing carbon fiber composite according to any one of (2) to (4), wherein the melting point of the polyethernitrile is 280 to 370°C. (6) A mobility component comprising the polyethernitrile-containing carbon fiber composite according to any one of (2) to (5). (7) A structural component comprising the polyethernitrile-containing carbon fiber composite according to any one of (2) to (5). (8) Mobility using the mobility component according to (6). (9) A structural material using the structural component according to (7).

[0013] According to the present invention, it is possible to provide a polyethernitrile and a polyethernitrile-containing carbon fiber composite material having excellent thermal stability.

[0014] The present invention will be described in detail below with reference to embodiments.

[0015] The polyethernitrile-containing carbon fiber composite of the present invention comprises a polyethernitrile and a carbon fiber, the polyethernitrile having N repeating units represented by formula (I) and M repeating units represented by formula (II), where N and M are integers satisfying the relationship 0<[N / (N+M)]≦1.00, and in thermogravimetric analysis (TG), when maintained in air at a temperature above the melting point +30° C. for 30 minutes, the weight loss rate based on the weight of the polyethernitrile contained in the polyethernitrile-containing carbon fiber composite is 5% or less, and the polyethernitrile content is 20 to 85% by weight. １ , Ar ２ each have one different skeleton selected from units represented by any one of formulas (a) to (f).

[0016]

[0017]

[0018] In the above formula (f), Y is a group selected from the following units: X is any one of a hydrogen atom, a methyl group, and a trifluoromethyl group.

[0019]

[0020] (1) Polyethernitrile The polyethernitrile of the present invention is a polyethernitrile having N repeating units represented by formula (I) and M repeating units represented by formula (II) in one molecule, where N and M are integers satisfying the relationship 0<[N / (N+M)]≦1.00.

[0021]

[0022] In the formula, Ar 1 and Ar ２ Each of the units has one different skeleton selected from units represented by the following formulas (a) to (f). R is an organic group selected from a linear organic group having 1 to 6 carbon atoms, a branched organic group having 3 to 6 carbon atoms, and a cyclic organic group having 3 to 6 carbon atoms. R may contain one or more atoms selected from an oxygen atom, a nitrogen atom, and a sulfur atom. a represents the number of substituents R. In formulas (a), (b), (c), (e), and (f), a is an integer of 0 to 4, and in formulas (I), (II), and (d), a is an integer of 0 to 3. A skeleton in which a is 0 is preferred from the viewpoint of industrial ease of use. When multiple Rs are present, the Rs may be the same or different.

[0023]

[0024] In the above formula (f), Y is a group selected from the following units: X is any one of a hydrogen atom, a methyl group, and a trifluoromethyl group.

[0025]

[0026] Ar in polyether nitrile １ The content (molar ratio) of the repeating unit represented by Ar is represented by [N / (N+M)]. ２The content (molar ratio) of the repeating unit represented by the formula is represented by [M / (N+M)], where N and M satisfy the relationship N≧M.

[0027] Since polyethernitriles with a lower melting point can be easily obtained, it is preferable that [N / (N+M)]<1.00. Since the melting point becomes lower as [N / (N+M)] becomes farther from 1.00, [N / (N+M)] is more preferably 0.99 or less, and even more preferably 0.97 or less. By lowering the melting point of the polyethernitrile, it is possible to easily obtain polyethernitriles with excellent processability.

[0028] Since highly crystalline polyethernitriles can be easily obtained, it is preferable that [N / (N+M)] is 0.60≦[N / (N+M)]. [N / (N+M)] is more preferably 0.80 or more, and even more preferably 0.90 or more. By making the polyethernitrile highly crystalline, it is possible to obtain polyethernitriles with excellent solvent resistance.

[0029] N and M are preferably integers satisfying the relationship 0.60≦[N / (N+M)]<1.00, more preferably integers satisfying the relationship 0.80≦[N / (N+M)]<1.00, even more preferably integers satisfying the relationship 0.80≦[N / (N+M)]≦0.99, and particularly preferably integers satisfying the relationship 0.90≦[N / (N+M)]≦0.97.

[0030] The range of the sum of N and M is not particularly limited, but is exemplified as a range of 5 to 10,000, preferably 5 to 5,000, more preferably 5 to 1,000, and most preferably 5 to 500.

[0031] The polyethernitrile of the present invention may contain a third repeating unit in addition to the repeating units represented by the above formula (I) and the repeating units represented by the above formula (II). In this case, the total molar ratio of the repeating units represented by the formula (I) and the repeating units represented by the formula (II) to all the repeating units in the polyethernitrile is preferably from 60 mol % to 100 mol %, more preferably from 80 mol % to 100 mol %, and most preferably from 90 mol % to 100 mol %.

[0032] In the polyether nitrile of the present invention, Ar １ is a skeleton represented by the formula (a) or the formula (e), and Ar ２ is one type of skeleton selected from the units represented by the formulas (a) to (f), and Ar １ In the polyether nitrile of the present invention, it is preferable that Ar １ is the skeleton represented by the formula (a), and Ar ２ It is more preferable that Ar is one kind of skeleton selected from the units represented by the formulas (b) to (f). １ is the skeleton represented by the formula (a) or the formula (e), and more preferably the skeleton represented by the formula (a), the thermal stability of the obtained polyether nitrile is more likely to be improved.

[0033] In the polyether nitrile of the present invention, it is more preferable that the repeating unit represented by formula (I) is a structural unit represented by formula (III) below, and the structural unit represented by formula (II) is a structural unit represented by formula (IV) below.

[0034]

[0035] In the formula, Ar 3 has one type of skeleton selected from units represented by any one of formulas (g) to (k). When the repeating unit represented by formula (I) is a structural unit represented by formula (III) below, the resulting polyether nitrile has excellent thermal stability, which is preferable.

[0036]

[0037] In the above formula (k), Y is a group selected from the following units: X is any one of a hydrogen atom, a methyl group, and a trifluoromethyl group.

[0038]

[0039] The polyethernitrile of the present invention preferably has a melting point of 280 to 370° C. By adjusting the melting point of the polyethernitrile to 280° C. or higher, a polyethernitrile-containing carbon fiber composite material having excellent thermal stability can be obtained. By adjusting the melting point of the polyethernitrile to 370° C. or lower, the processability of the polyethernitrile can be improved.

[0040] (2) Method for Producing Polyethernitrile The method for producing polyethernitrile is not particularly limited as long as it can synthesize a polyethernitrile that satisfies the requirement (1) above, and any production method can be used. For example, polyethernitrile can be produced by heating a mixture of an aromatic compound having two hydroxyl groups, an aromatic compound having a benzonitrile skeleton having two halogeno groups, and a base in an organic polar solvent. When producing polyethernitrile, one type or two or more types of aromatic compounds having two hydroxyl groups may be used.

[0041] The aromatic compound having two hydroxyl groups, the aromatic compound having a benzonitrile skeleton having two halogeno groups, the base, the organic polar solvent, and the reaction conditions used in an example of a method for producing a polyether nitrile are described below.

[0042] Examples of the aromatic compound having two hydroxyl groups in the method for producing polyether nitrile include compounds represented by the following general formulas (1) to (s).

[0043]

[0044] In the formula, R is any organic group selected from a linear organic group having 1 to 6 carbon atoms, a branched organic group having 3 to 6 carbon atoms, and a cyclic organic group having 3 to 6 carbon atoms. R may contain one or more atoms selected from an oxygen atom, a nitrogen atom, and a sulfur atom. In formulas (l) to (s), a represents the number of substituents R. In formulas (l), (o), (p), (r), and (s), a represents an integer of 0 to 4, and in formula (q) a represents an integer of 0 to 3. When multiple Rs are present, the Rs may be the same or different. In the above formula (s), Y is a group selected from the following units. X represents a hydrogen atom, a methyl group, or a trifluoromethyl group.

[0045]

[0046] Specific examples of aromatic compounds having two hydroxyl groups include hydroquinone, methylhydroquinone, methoxyhydroquinone, 2,6-dimethylhydroquinone, 2,3-dimethylhydroquinone, trimethylhydroquinone, tetramethylhydroquinone, 2,5-di-tert-butylhydroquinone, 2,5-di-tert-amylhydroquinone, 2-acetylhydroquinone, resorcinol, 5-methoxyresorcinol, 2-methylresorcinol, 5-methylresorcinol, 2,4-dihydroxybenzaldehyde, and 4-ethylresorcinol. resorcinol, 3,5-dihydroxyacetophenone, 4-butylresorcinol, 2-acetylresorcinol, 4-hexylresorcinol, 4-acetylresorcinol, 3,5-dihydroxybenzoic acid, 4-benzoylresorcinol, 4,6-diacetylresorcinol, 2,6-dihydroxybenzoic acid, 2,4-dihydroxybenzoic acid, 4-propionylresorcinol, 3,5-dihydroxybenzamide, 3,5-dihydroxy-4-methylbenzoic acid, 2-nitroresorcinol, 2,6-dihydroxy-4-methylbenzoic acid, 2,4-dihydroxybenzamide, 1,4-dihydroxynaphthalene, catechol, 4,4'-dihydroxybiphenyl, 2,5-dihydroxybenzoic acid, phenylhydroquinone, 2,5-dihydroxyterephthalic acid, 1,4-dihydroxy-2-naphthoic acid, 3,6-dihydroxybenzonorbornane, 2,3-dihydroxynaphthalene, 1,2-dihydroxynaphthalene, 4-methylcatechol, 3-methoxycatechol, 3-methylcatechol, 3,4-dihydroxybenzaldehyde, 4-tert-butylcatechol, 2, 3-Dihydroxybenzaldehyde, 3,4-dihydroxyacetophenone, 3,4-dihydroxybenzophenone, 3,5-di-tert-butylcatechol, 3,4-dihydroxybenzoic acid, 4-nitrocatechol, 2,3-dihydroxybenzoic acid, catechol-4-acetic acid, 4,4'-dihydroxy-3,3',5,5'-tetramethylbiphenyl, 3,3'-dihydroxybenzidine, 1,5-dihydroxynaphthalene, 1,6-dihydroxynaphthalene, 2,6-dihydroxynaphthalene, 2,7-dihydroxynaphthalene, 2,Examples of suitable aromatic compounds include 2'-bis(4-hydroxyphenyl)propane, bis(4-hydroxyphenyl)sulfone, 1,1'-bis(4-hydroxyphenyl)methane, 4,4'-dihydroxybenzophenone, 4,4'-dihydroxydiphenyl ether, and 2,2-bis(4-hydroxyphenyl)hexafluoropropane. Among these, hydroquinone, resorcinol, and 4,4'-dihydroxybiphenyl are preferred, with hydroquinone being more preferred because it is more likely to improve the thermal stability of the resulting polyethernitrile-containing carbon fiber composite. When two aromatic compounds having two hydroxyl groups are used, it is preferred that one of the two is hydroquinone, and that the amount of hydroquinone blended is greater than the amount of the other aromatic compound blended.

[0047] In the method for producing polyether nitrile, a compound represented by the following formula (t) can be preferably used as the compound having a benzonitrile skeleton having two halogeno groups.

[0048]

[0049] X is a chlorine atom or a fluorine atom. Examples of compounds having a benzonitrile skeleton with two halogeno groups include 2,6-dichlorobenzonitrile, 2,6-difluorobenzonitrile, and 2-chloro-6-fluorobenzonitrile. Of these, 2,6-dichlorobenzonitrile is preferred.

[0050] In the method for producing polyethernitrile, the amount of the compound having a benzonitrile skeleton with two halogeno groups per 1.00 mole of the aromatic compound having two hydroxyl groups is not particularly limited as long as it is in the range of 0.90 to 1.10 moles, but from the viewpoint of the physical properties of the resulting polymer, a range of 1.01 to 1.05 moles is preferred. When the amount of the compound having a benzonitrile skeleton with two halogeno groups is 1.01 moles or more per 1.00 mole of the aromatic compound having two hydroxyl groups, polyethernitrile with excellent heat resistance can be obtained. When the amount of the compound having a benzonitrile skeleton with two halogeno groups is 1.05 moles or less per 1.00 mole of the aromatic compound having two hydroxyl groups, the resulting polyethernitrile can have a high molecular weight.

[0051] In the method for producing polyether nitrile, the base may be an organic base or an inorganic base.The type of base is not limited, but from the viewpoint of ease of handling and reactivity, carbonates such as sodium carbonate and potassium carbonate, and bicarbonates such as sodium hydrogen carbonate and potassium hydrogen carbonate are preferred, and sodium carbonate or potassium carbonate is more preferred.

[0052] The organic polar solvent used in the method for producing polyethernitrile is not particularly limited as long as it does not inhibit the reaction, but N-methyl-2-pyrrolidone (NMP), dimethyl sulfoxide (DMSO), or sulfolane is preferred, and NMP is particularly preferred.

[0053] In the method for producing polyethernitrile, water is produced as a by-product as the reaction proceeds. In order to remove the by-product water, an organic compound that forms an azeotropic mixture with water can be added as needed. Such an organic compound is not particularly limited as long as it forms an azeotropic mixture with water, but a nonpolar organic solvent having a boiling point lower than that of the reaction solvent is preferred, and specifically, toluene can be mentioned.

[0054] The method for producing polyethernitrile is usually carried out under heating in a nitrogen atmosphere or under reduced pressure. The reaction temperature is preferably in the range of 150 to 200°C, and the temperature is raised stepwise. By raising the temperature stepwise, volatilization of the compound having a benzonitrile skeleton with two halogeno groups during polymerization is suppressed, and polyethernitrile with excellent thermal stability in air can be obtained.

[0055] The reaction time in the process for preparing polyethernitriles may vary depending to some extent on the reaction temperature, the nature of the reagents used and the presence of a solvent, but is preferably between 6 and 10 hours.

[0056] The produced polyethernitrile can be obtained by separating and recovering it from the reaction mixture obtained by the above-mentioned method. There are no particular limitations on the method for recovering the polyethernitrile from the reaction mixture, and examples thereof include a method of recovering the polyethernitrile by contacting the reaction mixture with a solvent that can dissolve the by-product salt, if necessary, under heating, or a method of removing the by-product salt and oligomers from the reaction mixture under reduced pressure.

[0057] In the method for producing a copolymerized polyethernitrile of the present invention, a terminal blocking agent may be used. The terminal blocking agent is an aromatic compound having one hydroxyl group. Specific examples include 4-phenylphenol, 2-phenylphenol, 3-phenylphenol, 4-phenoxyphenol, 1-naphthol, and 2-naphthol. A compound selected from 4-phenylphenol, 4-phenoxyphenol, 1-naphthol, and 2-naphthol is preferred, and a compound selected from 4-phenylphenol, 4-phenoxyphenol, 1-naphthol, and 2-naphthol is more preferred. By incorporating an aromatic compound having one hydroxyl group as a terminal blocking agent, polyethernitriles and polyethernitrile-containing carbon fiber composites having excellent heat resistance can be obtained.

[0058] The amount (mol) of the aromatic compound having one hydroxyl group to be blended is not particularly limited as long as it is in the range of 0.01 to 5.00 mol % relative to the total amount (mol) of the aromatic compound having two hydroxyl groups and the aromatic compound having a benzonitrile skeleton and two halogeno groups, but from the viewpoint of the physical properties of the resulting polymer, the range of 0.10 to 2.00 mol % is more preferable.

[0059] (3) Polyethernitrile-Containing Carbon Fiber Composite The polyethernitrile-containing carbon fiber composite of the present invention contains the polyethernitrile of the present invention and carbon fibers.

[0060] That is, the polyethernitrile-containing carbon fiber composite of the present invention comprises polyethernitrile and carbon fiber, the polyethernitrile having N repeating units represented by formula (I) and M repeating units represented by formula (II), N and M being integers satisfying the relationship 0<[N / (N+M)]≦1.00, and in thermogravimetric analysis (TG), when held in air at a temperature above the melting point +30°C for 30 minutes, the weight loss rate based on the weight of the polyethernitrile contained in the polyethernitrile-containing carbon fiber composite is 5% or less, and the polyethernitrile content is 20 to 85% by weight.

[0061]

[0062] In the formula, Ar １ and Ar ２ Each of the units has one different skeleton selected from units represented by the following formulas (a) to (f). R is an organic group selected from a linear organic group having 1 to 6 carbon atoms, a branched organic group having 3 to 6 carbon atoms, and a cyclic organic group having 3 to 6 carbon atoms. R may contain one or more atoms selected from oxygen atoms, nitrogen atoms, and sulfur atoms. a represents the number of substituents R. a in formulas (a), (b), (c), (e), and (f) is an integer of 0 to 4, and a in formulas (I), (II), and (d) is an integer of 0 to 3. When multiple Rs are present, the Rs may be the same or different.

[0063]

[0064] In the above formula (f), Y is a group selected from the following units: X is any one of a hydrogen atom, a methyl group, and a trifluoromethyl group.

[0065]

[0066] The carbon fiber may be either a continuous carbon fiber or a discontinuous carbon fiber. In order to obtain a polyethernitrile-containing carbon fiber composite material having excellent mechanical properties, the carbon fiber is preferably a continuous carbon fiber, and more preferably a carbon fiber bundle. The carbon fiber bundle refers to a bundle of multiple continuous carbon fibers.

[0067] The polyethernitrile-containing carbon fiber composite of the present invention may contain, as necessary, polymers other than polyethernitrile and various additives such as plasticizers, crystal nucleating agents, metal soaps, mold release agents, coloring inhibitors, lubricants, ultraviolet inhibitors, antioxidants, flame retardants, colorants, and foaming agents.

[0068] The polyethernitrile-containing carbon fiber composite material of the present invention can be produced by impregnating carbon fibers with polyethernitrile.

[0069] Examples of methods for impregnating continuous carbon fibers with polyethernitrile include a film impregnation method in which a film-like polyethernitrile is melted and pressurized to impregnate a carbon fiber bundle with the polyethernitrile, a commingle impregnation method in which continuous fibrous polyethernitrile is blended with a carbon fiber bundle and then the polyethernitrile is melted to impregnate the carbon fiber bundle with the polyethernitrile, a powder impregnation method in which powdered polyethernitrile is dispersed in gaps between fibers in a continuous carbon fiber bundle and then the polyethernitrile is melted to impregnate the carbon fiber bundle with the polyethernitrile, and a pultrusion impregnation method in which continuous carbon fiber bundles are immersed in molten polyethernitrile to impregnate the carbon fiber bundle with the polyethernitrile. Any of these methods may be used. The pultrusion impregnation method is particularly preferred.

[0070] As a method for impregnating a carbon fiber substrate made of discontinuous carbon fibers with polyethernitrile, for example, a method of supplying polyethernitrile by an extruder and impregnating the carbon fiber substrate, a method of dispersing powdered polyethernitrile in the fiber layer of a carbon fiber substrate made of discontinuous carbon fibers and then melting and impregnating the polyethernitrile, a method of forming polyethernitrile into a film and laminating it with a carbon fiber substrate made of discontinuous carbon fibers and then melting and impregnating the polyethernitrile, a method of dissolving polyethernitrile in a solvent and impregnating a carbon fiber substrate made of discontinuous carbon fibers in the state of a solution, and then volatilizing the solvent, a method of fiberizing polyethernitrile to form a mixed yarn with discontinuous fibers, etc. Any method may be used. Examples of carbon fiber substrates include unidirectional fabrics in which the fibers are aligned in approximately the same direction and integrated with auxiliary weft threads or binders, bidirectional fabrics in which carbon fibers are interwoven in two directions, multiaxial fabrics in which carbon fibers are interwoven in multiple directions, multiaxial stitch substrates in which sheets of carbon fibers aligned in one direction are stacked in multiple directions and integrated with stitch threads, braided cords, and nonwoven fabrics or mats using discontinuous fibers.

[0071] The polyethernitrile content in the polyethernitrile-containing carbon fiber composite of the present invention is 20 to 85% by weight. By making the polyethernitrile content 20% by weight or more, the strength of molded articles obtained using the polyethernitrile-containing carbon fiber composite can be improved. On the other hand, by making the polyethernitrile content 85% by weight or less, the strength of molded articles obtained using the polyethernitrile-containing carbon fiber composite can be improved. The content is more preferably 30% by weight or more, and even more preferably 40% by weight or more. The content is more preferably 70% by weight or less, and even more preferably 60% by weight or less. An example of a method for adjusting the content within the above range is a method in which the amounts of carbon fiber and polyethernitrile added are adjusted when producing a polyethernitrile-containing carbon fiber composite by the above-mentioned method.

[0072] The polyethernitrile content in the polyethernitrile-containing carbon fiber composite of the present invention can be calculated by measuring the weight of the polyethernitrile-containing carbon fiber composite, immersing it in N-methyl-2-pyrrolidone (NMP) at 200° C. to elute the polyethernitrile, and measuring the weight of the carbon fiber remaining as a residue. When the polyethernitrile-containing carbon fiber composite contains other polymers or various additives, the content of only the polyethernitrile excluding the other polymers and various additives is calculated and used as the polyethernitrile content in the polyethernitrile-containing carbon fiber composite.

[0073] One or more polyethernitrile-containing carbon fiber composite sheets are laminated in any desired configuration, and then molded while applying heat and / or pressure as necessary to obtain a molded product.

[0074] In thermogravimetric analysis (TG), the polyethernitrile-containing carbon fiber composite of the present invention exhibits a weight loss rate of 5% or less, based on the weight of the polyethernitrile contained in the polyethernitrile-containing carbon fiber composite, when maintained in air at a temperature above the melting point of 30°C for 30 minutes. A weight loss rate of 5% or less allows for the production of a polyethernitrile-containing carbon fiber composite with excellent thermal stability. "Excellent thermal stability" as used herein means that the weight loss rate of the polyethernitrile is small when maintained in air at a temperature above the melting point of 30°C for 30 minutes, i.e., excellent thermal stability in air. More specifically, when producing a polyethernitrile-containing carbon fiber composite from polyethernitrile and carbon fiber, the carbon fiber is typically impregnated at a temperature above the melting point of the polyethernitrile of 30°C. Furthermore, when the carbon fiber composite is used in the components described below, it may be melted and welded in air. Therefore, it is important to maintain a weight loss rate of 5% or less at a temperature above the melting point of the polyethernitrile of 30°C. The weight loss rate is preferably 1% or less, and more preferably 0%.

[0075] The weight of the polyethernitrile contained in the polyethernitrile-containing carbon fiber composite is determined, and using this as a standard, the weight loss rate is measured by the method described later in <Thermogravimetric analysis (TG) of polyethernitrile-containing carbon fiber composite>.

[0076] When the blending amounts of polyethernitrile and carbon fiber are known, the weight of polyethernitrile contained in a polyethernitrile-containing carbon fiber composite can be determined by subtracting the weight of carbon fiber from the weight of the polyethernitrile-containing carbon fiber composite. When the blending amounts of polyethernitrile and carbon fiber are unknown, the weight of the polyethernitrile-containing carbon fiber composite can be measured, and then the polyethernitrile is removed from the polyethernitrile-containing carbon fiber composite, and the weight can be measured, and the weight can be determined from the difference between the weights before and after polyethernitrile removal. One method for removing polyethernitrile from a polyethernitrile-containing carbon fiber composite is to immerse the composite in N-methyl-2-pyrrolidone (NMP) at 200°C and elute the polyethernitrile.

[0077] As a method for controlling the weight loss rate to 5% or less based on the weight of the polyethernitrile contained in the polyethernitrile-containing carbon fiber composite, for example, a method of adjusting the monomer composition constituting the polyethernitrile can be mentioned. More specifically, for example, a method of decreasing the weight loss rate by increasing the content of the skeleton represented by formula (III) or the skeleton represented by formula (a) in the constituting monomer composition can be mentioned.

[0078] The polyethernitrile-containing carbon fiber composite of the present invention has excellent mechanical properties. The inventors have found that polyethernitriles with excellent thermal stability (small weight loss rate in air) tend to have high interfacial shear strength between the polyethernitrile and carbon fiber. The polyethernitrile-containing carbon fiber composite of the present invention has excellent interfacial shear strength between the polyethernitrile and carbon fiber, and therefore the molded product has excellent tensile strength.

[0079] The polyethernitrile-containing carbon fiber composite of the present invention has excellent chemical resistance. Here, chemical resistance refers to solvent resistance. The solvent resistance is evaluated by the method described below in <Solvent Resistance Test for Polyethernitrile-Containing Carbon Fiber Composite>. The solvent resistance of the polyethernitrile-containing carbon fiber composite of the present invention is preferably B or higher, more preferably A or higher, in the solvent resistance test. As a method for obtaining a polyethernitrile-containing carbon fiber composite with excellent solvent resistance, for example, as described above, a method using a polyethernitrile having a molecular weight of 0.60≦[N / (N+M)] can be mentioned.

[0080] The polyethernitrile-containing carbon fiber composite of the present invention has excellent thermal stability, mechanical properties, and chemical resistance, and can be used for mobility components, structural materials, and other industrial components.

[0081] Examples of mobility components of the present invention include components for automobiles, aircraft, ships, motorcycles, drones, urban air mobility, and kick scooters. Examples of structural material components of the present invention include components for buildings, bridges, railways, roads, ports, etc. The polyethernitrile-containing carbon fiber composite of the present invention is particularly suitable for mobility components or structural material components that require excellent thermal stability, mechanical properties, and chemical resistance.

[0082] Mobility devices using mobility components containing the polyethernitrile-containing carbon fiber composite of the present invention exhibit excellent properties. Examples of the mobility devices of the present invention include automobiles, airplanes, ships, motorcycles, drones, urban air mobility devices, and kick scooters.

[0083] Structural materials using structural members containing the polyethernitrile-containing carbon fiber composite of the present invention exhibit excellent properties. Examples of structural materials of the present invention include buildings, bridges, railways, roads, and ports.

[0084] The present invention will be described in more detail below with reference to examples, which are illustrative and not limiting.

[0085] <Melting points of polyethernitrile and polyethernitrile-containing carbon fiber composites> The melting points of polyethernitrile were determined by measuring the polyethernitrile, and the melting points of polyethernitrile-containing carbon fiber composites were determined by measuring the polyethernitrile-containing carbon fiber composites. Note that, because carbon fibers do not melt in differential scanning calorimetry (DSC) measurements, the melting points of the polyethernitrile-containing carbon fiber composites are essentially the melting points of the polyethernitriles contained therein.

[0086] The melting point was determined by differential scanning calorimetry (DSC) using a Q20 thermometer manufactured by TA Instruments Co., Ltd. The sample was heated from 50°C to 400°C at a rate of 20°C / min, held at 400°C for 1 minute, then cooled from 400°C to 50°C at a rate of 20°C / min, heated again from 50°C to 400°C at a rate of 20°C / min, held at 400°C for 1 minute, and then cooled from 400°C to 100°C at a rate of 20°C / min. The endothermic peak temperature observed during the second heating was taken as the melting point.

[0087] <Thermogravimetric analysis (TG) of polyethernitrile> The weight loss rate when polyethernitrile was held at melting point + 30°C for 30 minutes was measured using a TGA7 manufactured by PerkinElmer. The polyethernitrile was held at 50°C for 1 minute in an air flow, then heated to melting point + 30°C at a heating rate of 20°C / min, and held at melting point + 30°C for 30 minutes. The weight loss rate from holding at 50°C for 1 minute to holding at melting point + 30°C for 30 minutes was calculated.

[0088] <Thermogravimetric analysis (TG) of polyethernitrile-containing carbon fiber composite> The weight loss rate when a polyethernitrile-containing carbon fiber composite was held at melting point + 30°C for 30 minutes was measured using a TGA7 manufactured by PerkinElmer. The polyethernitrile-containing carbon fiber composite was held at 50°C for 1 minute in an air flow, then heated to melting point + 30°C at a heating rate of 20°C / min, and held at melting point + 30°C for 30 minutes. The weight loss rate from holding at 50°C for 1 minute to holding at melting point + 30°C for 30 minutes was calculated based on the weight of polyethernitrile contained in the polyethernitrile-containing carbon fiber composite.

[0089] <Solvent Resistance Test of Polyethernitrile-Containing Carbon Fiber Composite> A polyethernitrile-containing carbon fiber composite was cut into a 1 cm square and immersed in NMP at 80° C. After the liquid temperature was kept at 80° C. for 20 minutes, the state of the polyethernitrile-containing carbon fiber composite after the treatment was visually inspected and evaluated according to the following criteria.

[0090] A: No change in shape was observed. B: Swollen. C: The polyether nitrile was dissolved and the carbon fibers were opened.

[0091] <Raw Materials Used in the Examples> Hydroquinone (FUJIFILM Wako Pure Chemical Industries, Ltd.) Resorcinol (FUJIFILM Wako Pure Chemical Industries, Ltd.) 4,4'-Dihydroxybiphenyl (Tokyo Chemical Industry Co., Ltd.) 2,6-Dichlorobenzonitrile (Tokyo Chemical Industry Co., Ltd.) Sodium Carbonate (Kanto Chemical Co., Ltd.) NMP (FUJIFILM Wako Pure Chemical Industries, Ltd.) Carbon Fiber Bundle (Toray Industries, Inc., T700S-12K). 4-Phenoxyphenol (Kanto Chemical Co., Ltd.) <Evaluation of Interfacial Shear Strength Between Polyethernitrile and Carbon Fiber> The interfacial shear strength between polyethernitrile and carbon fiber was measured using a nanoindenter TI950 manufactured by Hysitron. As described in Example 9, polyethernitrile and carbon fiber cut to a length of 1 cm were melt-kneaded and then injection-molded to obtain ISO527-2-1A dumbbell test specimens. A thin piece of 18 μm thickness was cut out from the dumbbell test piece and used as a sample. The interfacial shear strength between the polyether nitrile and carbon fiber was measured by pushing out one fiber in the sample with a flat-tipped indenter. The average of five measurements was used as the measured value.

[0092] <Mechanical Properties> Using the ISO 527-2-1A dumbbell test pieces obtained in the same manner as above as samples, the tensile strength was measured in accordance with ISO 527-1 using an AG-50kNx universal testing machine manufactured by Shimadzu Corporation. The average of five measurements was taken as the measured value.

[0093] Example 1: A 3-L separable flask equipped with a stirrer, a nitrogen inlet tube, and a Dean-Stark tube was charged with 88.1 g (800 mmol) of hydroquinone, 140.4 g (816 mmol) of 2,6-dichlorobenzonitrile, and 101.8 g (960 mmol) of sodium carbonate. Under a nitrogen atmosphere, 800 mL of NMP and 30 mL of toluene were added, and the mixture was reacted at 160°C for 2 hours, 180°C for 2 hours, and then at 200°C for 8 hours. After completion of the reaction, the reaction solution was discharged into a receiving vessel containing 3 L of a mixed solvent of NMP:water = 8:2 (volume ratio), thereby precipitating polyethernitrile and obtaining particles. The obtained particles were washed three times with 3 L of a mixed solvent of NMP:water = 8:2 (volume ratio) (room temperature) and then three times with 3 L of warm water (80°C), and then vacuum dried overnight at 80°C to obtain polyethernitrile particles. The copolymerization ratio of the obtained polyethernitrile particles was [N / (N+M)]=1.00, and the melting point of the obtained polyethernitrile particles was 388°C.

[0094] The polyethernitrile particles obtained as described above were supplied in a fixed quantity from a feeder to an impregnation die set at a melting point of +30°C (418°C). Sixteen bobbins wound with carbon fiber bundles (T700S-12K) were prepared, and the carbon fiber bundles were continuously fed from each bobbin through a yarn guide. The fed 16 carbon fiber bundles were set to a width of 50 mm and passed through the impregnation die. In this way, the carbon fiber bundles continuously passing through the impregnation die were impregnated with polyethernitrile. The polyethernitrile-impregnated carbon fiber was continuously drawn from the nozzle of the impregnation die using a take-up roll at a speed of 1 m per minute. The drawn carbon fiber bundle was cooled on a cooling roll and then wound on a winder to obtain a polyethernitrile-containing carbon fiber composite having a polyethernitrile content of 50 wt%.

[0095] The resulting polyethernitrile and polyethernitrile-containing carbon fiber composite were analyzed by the methods described above. The weight loss rate in air, melting point, and solvent resistance were as shown in Table 1.

[0096] [Examples 2 to 8, Comparative Examples 1 and 2] The same procedure as in Example 1 was carried out, except that the type and amount of the aromatic compound having two hydroxyl groups were changed as shown in Tables 1 and 2. The obtained polyethernitrile-containing carbon fiber composites were analyzed by the methods described above. The weight loss rate in air, melting point, and solvent resistance are shown in Tables 1 and 2.

[0097] [Example 9, Comparative Example 3] Polyethernitrile particles were obtained by the same procedure as in Example 1, except that the type and amount of the aromatic compound having two hydroxyl groups were changed as shown in Table 2. The obtained polyethernitrile particles and carbon fiber (T700S-12K) cut to 1 cm lengths were mixed in a weight ratio of 85:15, kneaded using a small kneader (Thermo Scientific, HAKKE MIniLab2) at a temperature of the melting point + 30 ° C (418 ° C), and then pelletized. The obtained pellets were used to prepare dumbbell test specimens in accordance with ISO 527-2-1A at a temperature of the melting point + 30 ° C (418 ° C) using a small molding machine (Thermo Scientific, HAKKE MIniJet pro). Using dumbbell test pieces of the resulting polyethernitrile-containing carbon fiber composite material with a polyethernitrile content of 85% by weight, the tensile strength and the interfacial shear strength between the polyethernitrile and the carbon fiber were measured. The results are shown in Table 2.

[0098] Example 10 The same procedure as in Example 1 was carried out, except that the type and amount of the aromatic compound having two hydroxyl groups was changed as shown in Table 2, and 4-phenoxyphenol was added as an end-capping agent in the amount shown in Table 2 at the same time as adding the aromatic compound having two hydroxyl groups. The obtained polyethernitrile-containing carbon fiber composite was analyzed by the above-mentioned methods. The weight loss rate in air, melting point, and solvent resistance are shown in Table 2.

[0099]

[0100]

[0101] A comparison of Examples 1 to 8 with Comparative Examples 1 and 2 reveals that when the main monomer is hydroquinone, the thermal stability (weight loss rate in air) of polyethernitrile and polyethernitrile composite materials is excellent.

[0102] Furthermore, a comparison between Example 1 and Example 2, and a comparison between Example 7 and Example 8 shows that when [N / (N+M)]<1.00 is satisfied, the melting point of the polyether nitrile can be made lower than when [N / (N+M)]=1.00, and the melting point will be 370°C or lower.

[0103] A comparison between Example 4 and Example 5 shows that when 0.80≦[N / (N+M)] is satisfied, the solvent resistance of the polyether nitrile composite material is particularly excellent.

[0104] Comparison of Examples 6 and 9 with Comparative Example 3 reveals that the polyethernitrile composites of Examples 6 and 9, which have excellent thermal stability (small weight loss rate in air), have high interfacial shear strength between the polyethernitrile and carbon fiber, and high tensile strength.

[0105] A comparison of Example 10 and Comparative Example 3 shows that the thermal stability of the polyether nitrile composite material is improved (the weight loss rate in air is reduced) by carrying out end-capping.

Claims

1. A polyether nitrile having N repeating units represented by formula (I) and M repeating units represented by formula (II), where N and M are integers satisfying the relationship 0<[N / (N+M)]≦1.00, and which, in thermogravimetric analysis (TG), has a weight loss rate of 5% or less when held in air at melting point +30°C for 30 minutes: In the formula, Ar １ and Ar ２ each have one different type of skeleton selected from units represented by the following formula (a) to formula (f); R is any organic group selected from a linear organic group having 1 to 6 carbon atoms, a branched organic group having 3 to 6 carbon atoms, and a cyclic organic group having 3 to 6 carbon atoms; R may contain one or more atoms selected from an oxygen atom, a nitrogen atom, and a sulfur atom; a represents the number of substituents R; a in formulas (a), (b), (c), (e), and (f) is an integer of 0 to 4, and a in formulas (I), (II), and (d) is an integer of 0 to 3; when a plurality of R are present, R may be the same or different from each other; In the above formula (f), Y is a group selected from the following units; X is any one of a hydrogen atom, a methyl group, and a trifluoromethyl group.

2. A polyethernitrile-containing carbon fiber composite material comprising the polyethernitrile according to claim 1 and carbon fiber, wherein the polyethernitrile-containing carbon fiber composite material has a weight loss rate of 5% or less when held in air at a temperature 30°C above the melting point of the polyethernitrile for 30 minutes in thermogravimetric analysis (TG), and the polyethernitrile content is 20 to 85% by weight.

3. Ar １ is a skeleton represented by the formula (a) or the formula (e), and Ar ２ is one type of skeleton selected from the units represented by the formulas (a) to (f), and Ar １ The polyethernitrile-containing carbon fiber composite according to claim 2, wherein the backbone is different from that of the polyethernitrile-containing carbon fiber composite.

4. The polyethernitrile-containing carbon fiber composite material according to claim 2 or 3, wherein N and M are integers satisfying the relationship 0.80≦[N / (N+M)]<1.

00.

5. The polyethernitrile-containing carbon fiber composite material according to claim 2 or 3, wherein the melting point of the polyethernitrile is 280 to 370°C.

6. A mobility component comprising the polyethernitrile-containing carbon fiber composite material according to claim 2 or 3.

7. A structural material member comprising the polyethernitrile-containing carbon fiber composite material according to claim 2 or 3.

8. Mobility using the mobility component according to claim 6.

9. A structural material using the structural material member according to claim 7.