JP6135297B2 - Fiber-reinforced polyimide composite material and method for producing the same - Google Patents

Description

  The present invention relates to a multilayer fiber reinforced polyimide composite having a high heat resistant core layer in which a sheet-like reinforcing fiber is impregnated with a high heat resistant polyimide resin and a heat-fusible surface layer made of a thermoplastic polyimide resin. The present invention relates to a material and a manufacturing method thereof.

  A fiber reinforced composite material composed of a reinforced fiber and a matrix resin has been widely applied to applications such as aerospace products, taking advantage of its excellent specific strength and specific elasticity. An epoxy resin is mainly used as the matrix resin, but the epoxy resin-based composite material cannot be used as a high-temperature member because its use limit temperature is about 120 ° C. For this reason, as a high temperature member, a metal such as a titanium alloy is actually used. On the other hand, polyimide resin is attracting attention as a material that substitutes for these metals because of its high heat resistance, and various studies have been conducted as a matrix resin for fiber-reinforced composite materials.

  Polyimide resins are generally insoluble and infusible, and have poor fluidity at high temperatures, so it has been considered difficult to combine them with fibers. However, in the latter half of the 1960s, the use of addition-type polyimide that hardens by heating, starting with a fiber reinforced polyimide composite material using the PMR method (in situ polymerization of monomer reactants), in which monomers developed by NASA are heated and polymerized directly Fiber reinforced composite materials that have been released one after another.

  For example, there are imide oligomers for liquid molding (commonly known as PETI-330) as in Patent Document 1 and Patent Document 2, and recently, a process by using an imide oligomer solution in a liquid molding method as in Patent Document 3 A simplified method has also been developed. The fiber-reinforced polyimide composite material obtained by these methods is characterized by being capable of impregnating polyimide into reinforcing fibers and fiber fabrics and having very high heat resistance.

  However, in any of these methods, since the polyimide used is an addition-type polyimide, a resin curing step by heat treatment is required after molding, and as a result, the productivity of the fiber reinforced composite material is poor. there were. In addition, cost-insensitive development has been performed, for example, special monomers must be used to improve heat resistance.

  Here, in order to solve these problems, the use of a thermoplastic polyimide can be considered. However, the known thermoplastic polyimide has a low glass transition temperature of 300 ° C. or lower, and the thermoplastic polyimide has both heat resistance and strength. Preparation of fiber reinforced composite materials has been considered difficult.

  As an improvement method, Patent Document 4 describes a fiber reinforced resin matrix prepreg having an outer layer containing a granular thermoplastic resin, and describes that toughness and impact resistance are improved. However, such a method of adhering resin particles has a problem that the work process becomes complicated and it is difficult to adjust the adhesion amount. Patent Document 5 describes a laminated structure in which a fiber reinforced polyimide resin layer and a polyimide film as a heat fusion layer are alternately laminated, and it is described that heat resistance and curing time can be shortened. Yes. However, since the number of sheets to be laminated increases, the work process becomes complicated, and bubbles and / or interfaces mixed therein may increase, which may reduce the delamination strength.

JP 2003-105083 A US Pat. No. 6,359,107 JP 2006-117788 A JP-A-2-31538 JP-A-63-264351

  An object of this invention is to provide the fiber reinforced polyimide composite material which is excellent in heat resistance and intensity | strength and can manufacture a laminated molded object easily at low cost.

化学式（１）において、
Ａ¹は４価のフェニル基及びビフェニル基からなる群から選択される基であり、Ｂ¹は２価のフェニル基及びジフェニルエーテル基からなる群から選択される基である。

化学式（２）において、
Ａ²は４価のフェニル基及びビフェニル基からなる群から選択される基であり、Ｂ²は５０モル％以上が下記化学式（３）で表される２価の基である。

化学式（３）において、
ＲはＯ、Ｃ（ＣＨ₃）₂、ＣＨ₂、ＳＯ₂、Ｓ、又は直接結合であり、各結合におけるＲは同一でも異なっていてもよく、ｍは１〜４の整数である。
２． 化学式（１）におけるＡ¹は、その９０モル％以上が３，３’，４，４’−ビフェニルテトラカルボン酸からカルボキシル基を除いた４価の基であり、化学式（２）におけるＡ²は、その５０モル％以上が３，３’，４，４’−ビフェニルテトラカルボン酸からカルボキシル基を除いた４価の基であることを特徴とする前記項１に記載の繊維強化ポリイミド複合材料。
３． 化学式（２）におけるＢ²は、その５０モル％以上が１，３−ビス（４−アミノフェノキシ）ベンゼン、１，４−ビス（４−アミノフェノキシ）ベンゼン、２，２−ビス〔４−（４−アミノフェノキシ）フェニル〕プロパン、４，４’−ビス（４−アミノフェノキシ）ビフェニル、及びビス〔４−（４−アミノフェノキシ）フェニル〕スルホンからなる群から選択されるジアミンからアミノ基を除いた２価の基であることを特徴とする前記項１又は２に記載の繊維強化ポリイミド複合材料。 The present invention relates to the following items.
1. Fiber reinforcement characterized by having a core layer in which a sheet-like reinforcing fiber is impregnated with a polyimide resin represented by the following chemical formula (1) and a surface layer made of a thermoplastic polyimide resin represented by the following chemical formula (2) Polyimide composite material.

In chemical formula (1),
A ¹ is a group selected from the group consisting of a tetravalent phenyl group and a biphenyl group, and B ¹ is a group selected from the group consisting of a divalent phenyl group and a diphenyl ether group.

In chemical formula (2),
A ² is a group selected from the group consisting of a tetravalent phenyl group and a biphenyl group, and B ² is a divalent group of which 50 mol% or more is represented by the following chemical formula (3).

In chemical formula (3),
R is O, C (CH ₃ ) ₂ , CH ₂ , SO ₂ , S, or a direct bond, R in each bond may be the same or different, and m is an integer of 1 to 4.
2. A ¹ in chemical formula (1) is a tetravalent group in which 90 mol% or more thereof is obtained by removing a carboxyl group from 3,3 ′, 4,4′-biphenyltetracarboxylic acid, and A ² in chemical formula (2) is The fiber-reinforced polyimide composite material according to Item 1, wherein 50 mol% or more thereof is a tetravalent group obtained by removing a carboxyl group from 3,3 ′, 4,4′-biphenyltetracarboxylic acid.
3. B ² in the chemical formula (2) is 50 mol% or more of 1,3-bis (4-aminophenoxy) benzene, 1,4-bis (4-aminophenoxy) benzene, 2,2-bis [4- ( Amino group is removed from a diamine selected from the group consisting of 4-aminophenoxy) phenyl] propane, 4,4′-bis (4-aminophenoxy) biphenyl, and bis [4- (4-aminophenoxy) phenyl] sulfone 3. The fiber-reinforced polyimide composite material according to item 1 or 2, which is a divalent group.

4). 4. A laminated molded body obtained by laminating the fiber-reinforced polyimide composite material according to any one of Items 1 to 3, and heating and molding under pressure.

化学式（４）において、
Ａ¹は４価のフェニル基及びビフェニル基からなる群から選択される基であり、Ｂ¹は２価のフェニル基及びジフェニルエーテル基からなる群から選択される基である。

化学式（５）において、
Ａ²は４価のフェニル基及びビフェニル基からなる群から選択される基であり、Ｂ²は５０モル％以上が下記化学式（３）で表される２価の基である。

化学式（３）において、
ＲはＯ、Ｃ（ＣＨ₃）₂、ＣＨ₂、ＳＯ₂、Ｓ、又は直接結合であり、各結合におけるＲは同一でも異なっていてもよく、ｍは１〜４の整数である。
６． 化学式（４）におけるＡ¹は、その９０モル％以上が３，３’，４，４’−ビフェニルテトラカルボン酸からカルボキシル基を除いた４価の基であり、化学式（５）におけるＡ²は、その５０モル％以上が３，３’，４，４’−ビフェニルテトラカルボン酸からカルボキシル基を除いた４価の基であることを特徴とする前記項５に記載の繊維強化ポリイミド複合材料の製造方法。
７． 化学式（５）におけるＢ²は、その５０モル％以上が１，３−ビス（４−アミノフェノキシ）ベンゼン、１，４−ビス（４−アミノフェノキシ）ベンゼン、２，２−ビス〔４−（４−アミノフェノキシ）フェニル〕プロパン、４，４’−ビス（４−アミノフェノキシ）ビフェニル、及びビス〔４−（４−アミノフェノキシ）フェニル〕スルホンからなる群から選択されるジアミンからアミノ基を除いた２価の基であることを特徴とする前記項５又は６に記載の繊維強化ポリイミド複合材料の製造方法。 5). A fiber characterized by impregnating a reinforcing fiber with a polyamic acid represented by the following chemical formula (4), creating a prepreg coated with the polyamic acid represented by the following chemical formula (5) on the surface, and curing the prepreg. A method for producing a reinforced polyimide composite material.

In chemical formula (4),
A ¹ is a group selected from the group consisting of a tetravalent phenyl group and a biphenyl group, and B ¹ is a group selected from the group consisting of a divalent phenyl group and a diphenyl ether group.

In chemical formula (5),
A ² is a group selected from the group consisting of a tetravalent phenyl group and a biphenyl group, and B ² is a divalent group of which 50 mol% or more is represented by the following chemical formula (3).

In chemical formula (3),
R is O, C (CH ₃ ) ₂ , CH ₂ , SO ₂ , S, or a direct bond, R in each bond may be the same or different, and m is an integer of 1 to 4.
6). A ¹ in chemical formula (4) is a tetravalent group in which 90 mol% or more thereof is obtained by removing a carboxyl group from 3,3 ′, 4,4′-biphenyltetracarboxylic acid, and A ² in chemical formula (5) is The fiber reinforced polyimide composite material according to Item 5, wherein 50 mol% or more thereof is a tetravalent group obtained by removing a carboxyl group from 3,3 ′, 4,4′-biphenyltetracarboxylic acid. Production method.
7). B ² in the chemical formula (5) is 50 mol% or more of 1,3-bis (4-aminophenoxy) benzene, 1,4-bis (4-aminophenoxy) benzene, 2,2-bis [4- ( Amino group is removed from a diamine selected from the group consisting of 4-aminophenoxy) phenyl] propane, 4,4′-bis (4-aminophenoxy) biphenyl, and bis [4- (4-aminophenoxy) phenyl] sulfone Item 7. The method for producing a fiber-reinforced polyimide composite material according to Item 5 or 6, which is a divalent group.

  According to the present invention, it is possible to provide a fiber-reinforced polyimide composite material that is excellent in heat resistance and strength and that can easily produce a laminated molded body at low cost. The fiber-reinforced polyimide composite material of the present invention is easy to manufacture and handle, and has excellent delamination strength when formed into a laminate, so that it can be used in the aerospace field, automobiles, transportation equipment, building structures, bridges. It can be suitably used as a heat-resistant structural material in a field such as a field.

  The fiber-reinforced polyimide composite material of the present invention is a material in which a heat-sealing layer is provided on the surface layer of a highly heat-resistant core layer composed of sheet-like reinforcing fibers and a highly heat-resistant resin. That is, a multilayer having a core layer impregnated with a highly heat-resistant polyimide resin that does not exhibit fluidity even at a high temperature of 300 ° C. or higher on a sheet-like reinforcing fiber, and a heat-fusible surface layer made of a thermoplastic polyimide resin A fiber reinforced composite material with a structure.

  The polyimide resin used by this invention can be manufactured by imidating the polyamic acid obtained by making tetracarboxylic dianhydride and diamine react in an organic solvent. By selecting a combination of tetracarboxylic dianhydride and diamine, both a high heat-resistant polyimide resin and a thermoplastic polyimide resin can be produced.

  The tetracarboxylic dianhydride that can be used in the present invention is not particularly limited, but aromatic tetracarboxylic dianhydride and alicyclic tetracarboxylic dianhydride are preferred from the characteristics of the resulting polyimide. For example, 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride, 2,3,3 ′, 4′-biphenyltetracarboxylic dianhydride, 2,2 ′, 3,3′-biphenyltetra Carboxylic dianhydride, pyromellitic dianhydride, 3,3 ′, 4,4′-benzophenone tetracarboxylic dianhydride, oxydiphthalic dianhydride, diphenylsulfone tetracarboxylic dianhydride, p-terphenyl Tetracarboxylic dianhydride, m-terphenyltetracarboxylic dianhydride, cyclobutane-1,2,3,4-tetracarboxylic dianhydride, and 1,2,4,5-cyclohexanetetracarboxylic dianhydride A thing etc. can be mentioned suitably. In the present invention, from the viewpoint of heat resistance and mechanical properties, pyromellitic dianhydride, 2,3,3 ′, 4′-biphenyltetracarboxylic dianhydride, and 3,3 ′, 4,4 ′. -Biphenyltetracarboxylic dianhydride is preferred. In particular, 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride is preferably used as a main component. Moreover, the above-mentioned tetracarboxylic dianhydride does not need to be 1 type, and may be a mixture of multiple types.

  Examples of diamines that can be used in the present invention include 4,4′-diaminodiphenyl ether, 4,4′-diaminodiphenylmethane, 3,3′-diaminodiphenylmethane, 3,3′-dichlorobenzidine, and 4,4′-diaminodiphenyl. Sulfide, 3,3′-diaminodiphenylsulfone, 1,5-diaminonaphthalene, m-phenylenediamine, p-phenylenediamine, 3,3′-dimethyl-4,4′-biphenyldiamine, benzidine, 3,3′- Dimethylbenzidine, 3,3′-dimethoxybenzidine, 4,4′-diaminodiphenylsulfone, 4,4′-diaminodiphenylpropane, 2,4-diaminotoluene, bis (4-amino-3-carboxyphenyl) methane, 1 , 3-Bis (4-aminophenoxy) benzene, 1,4 Bis (4-aminophenoxy) benzene, 2,2-bis [4- (4-aminophenoxy) phenyl] propane, bis [4- (4-aminophenoxy) phenyl] sulfone, 2,4-bis (β-amino) -Tert-butyl) toluene, bis (p-β-amino-tert-butylphenyl) ether, bis (p-β-methyl-6-aminophenyl) benzene, bis-p- (1,1-dimethyl-5-) Amino-pentyl) benzene, 1-isopropyl-2,4-m-phenylenediamine, m-xylylenediamine, p-xylylenediamine, 2,2-bis [4- (4-aminophenoxy) phenyl] propane, and the like Diamines containing alicyclic structures such as aromatic diamines, di (p-aminocyclohexyl) methane, and 1,4-diaminocyclohexane, Diamine, heptamethylenediamine, octamethylenediamine, nonamethylenediamine, decamethylenediamine, diaminopropyltetramethylene, 3-methylheptamethylenediamine, 4,4-dimethylheptamethylenediamine, 2,11-diaminododecane, 1,2 -Bis-3-aminopropoxyethane, 2,2-dimethylpropylenediamine, 3-methoxyhexamethylenediamine, 2,5-dimethylhexamethylenediamine, 2,5-dimethylheptamethylenediamine, 3-methylheptamethylenediamine, Preferable examples include aliphatic diamines such as 5-methylnonamethylenediamine, 2,17-diaminoeicosadecane, 1,10-diamino-1,10-dimethyldecane, and 1,12-diaminooctadecane. The aforementioned diamine need not be a single type, and may be a mixture of a plurality of types.

  Among these diamines, 4,4'-diaminodiphenyl ether and p-phenylenediamine are preferably used in order to obtain a highly heat-resistant polyimide resin. In order to obtain a thermoplastic polyimide resin, 1,3-bis (4-aminophenoxy) benzene and 2,2-bis [4- (4-aminophenoxy) phenyl] propane should be used. preferable.

化学式（１）において、
Ａ¹は４価のフェニル基及びビフェニル基からなる群から選択される基であり、Ｂ¹は２価のフェニル基及びジフェニルエーテル基からなる群から選択される基である。 In the composite material of the present invention, the polyimide resin used for the core layer has high heat resistance, and preferably does not exhibit fluidity even in a temperature range of 300 ° C. or higher, for example. Specifically, a polyimide resin represented by the following chemical formula (1) is preferable.

In chemical formula (1),
A ¹ is a group selected from the group consisting of a tetravalent phenyl group and a biphenyl group, and B ¹ is a group selected from the group consisting of a divalent phenyl group and a diphenyl ether group.

In particular, in the chemical formula (1), A ¹ is 90 mol% or more, preferably 95 mol% or more is a tetravalent unit represented by the following chemical formula (6), and B ¹ is the following chemical formula (7) Or the polyimide resin which is a bivalent unit represented by either or both of (8) is excellent in heat resistance and mechanical characteristics, and is preferable.

化学式（２）において、
Ａ²は４価のフェニル基及びビフェニル基からなる群から選択される基であり、Ｂ²は５０モル％以上が下記化学式（３）で表される２価の基である。

化学式（３）において、
ＲはＯ、Ｃ（ＣＨ₃）₂、ＣＨ₂、ＳＯ₂、Ｓ、又は直接結合であり、各結合におけるＲは同一でも異なっていてもよく、ｍは１〜４の整数である。 In the composite material of the present invention, the surface layer is heat-fusible, and the polyimide resin used for this is thermoplastic. For example, a thermoplastic polyimide resin having a glass transition point (Tg) in the range of 100 ° C. to 400 ° C., preferably 200 ° C. to 300 ° C. is preferable. When the glass transition point is lower than this temperature range, the heat resistance of the fiber reinforced polyimide composite material obtained and the laminated molded body using the fiber reinforced polyimide composite material may not be sufficient. Further, if the glass transition point is higher than this temperature range, processing may be difficult. Specifically, a polyimide resin represented by the following chemical formula (2) is preferable.

In chemical formula (2),
A ² is a group selected from the group consisting of a tetravalent phenyl group and a biphenyl group, and B ² is a divalent group of which 50 mol% or more is represented by the following chemical formula (3).

In chemical formula (3),
R is O, C (CH ₃ ) ₂ , CH ₂ , SO ₂ , S, or a direct bond, R in each bond may be the same or different, and m is an integer of 1 to 4.

In particular, in the chemical formula (2), A ² is 50 mol% or more, preferably 70 mol% or more is a tetravalent unit represented by the following chemical formula (6), and B ² is 50 mol% or more, Preferably, a polyimide resin in which 70 mol% or more is a divalent unit represented by either the following chemical formula (9) or (10), or both, has an excellent balance between heat resistance and heat-fusibility. It is preferable.

  The composite material of the present invention is obtained by, for example, impregnating a reinforcing fiber sheet with a polyamic acid (polyimide precursor) that gives a high heat-resistant polyimide resin, and then applying a polyamic acid that gives a thermoplastic polyimide resin to the surface. It can be produced by heating to remove the solvent and imidization to cure. It can also be produced by impregnating a reinforcing fiber sheet with a polyamic acid that gives a high heat-resistant polyimide resin and curing, and then applying and curing a polyamic acid that gives a thermoplastic polyimide resin on the surface. The surface layer made of the thermoplastic polyimide resin may be formed only on one side of the core layer or on both sides.

  The polyamic acid is obtained by using tetracarboxylic dianhydride and diamine in approximately equimolar amounts and reacting at a relatively low temperature of 100 ° C. or lower, preferably 80 ° C. or lower to suppress the imidization reaction. can get. Although not limited, the normal reaction temperature is 25 ° C to 100 ° C, preferably 30 ° C to 80 ° C, more preferably 40 ° C to 70 ° C, and the reaction time is about 0.1 to 24 hours, preferably It is about 2 to 12 hours. By setting the reaction temperature and the reaction time within the above ranges, a high molecular weight polyamic acid solution can be easily obtained with high production efficiency. The reaction may be carried out in an air atmosphere, but is usually suitably carried out in an inert gas, preferably a nitrogen gas atmosphere. The substantially equimolar amount of tetracarboxylic dianhydride and diamine is specifically about 0.90 to 1.10, preferably 0.95 to 1 in terms of their molar ratio [tetracarboxylic dianhydride / diamine]. .05 or so.

  Although it does not specifically limit as a solvent used when preparing a polyamic acid, For example, N, N-dimethylformamide, N, N-dimethylacetamide, N, N-diethylacetamide, N-methyl-2-pyrrolidone, N Amide solvents such as ethyl-2-pyrrolidone and N-vinyl-2-pyrrolidone, γ-butyrolactone, γ-valerolactone, δ-valerolactone, γ-caprolactone, ε-caprolactone, α-methyl-γ-butyrolactone, etc. Cyclic ester solvents, carbonate solvents such as ethylene carbonate and propylene carbonate, glycol solvents such as triethylene glycol, m-cresol, p-cresol, 3-chlorophenol, phenol solvents such as 4-chlorophenol, acetophenone, 1, 3-Dimethyl-2-imidazo Jin Won, sulfolane, and dimethyl sulfoxide. Furthermore, other common organic solvents such as alcohol solvents such as methanol and ethanol, phenol, o-cresol, butyl acetate, ethyl acetate, isobutyl acetate, propylene glycol methyl acetate, ethyl cellosolve, butyl cellosolve, 2-methyl Cellosolve acetate, ethyl cellosolve acetate, butyl cellosolve acetate, tetrahydrofuran, dimethoxyethane, diethoxyethane, dibutyl ether, diethylene glycol dimethyl ether, methyl isobutyl ketone, diisobutyl ketone, cyclopentanone, cyclohexanone, methyl ethyl ketone, acetone, butanol, xylene, toluene, chlorobenzene N-methylcaprolactam, hexamethylphosphorotriamide, bis (2-methoxy Til) ether, 1,2-bis (2-methoxyethoxy) ethane, bis [2- (2-methoxyethoxy) ethyl] ether, 1,4-dioxane, dimethyl sulfoxide, dimethyl sulfone, diphenyl ether, diphenyl sulfone, tetramethyl Urea, trimethyl phosphate, triethyl phosphate, tributyl phosphate, anisole, terpenes, mineral spirits, petroleum naphtha solvents, biodegradable methyl lactate, ethyl lactate, butyl lactate and the like can also be used. The solvent used may be one type or two or more types.

  The polyamic acid has a logarithmic viscosity measured at a temperature of 30 ° C. and a concentration of 0.5 g / 100 mL of 0.2 or more, preferably 0.4 or more, more preferably 0.6 or more, still more preferably 0.8 or more, particularly preferably Is preferably a high molecular weight of 1.0 or more. When the logarithmic viscosity is lower than the above range, it may be difficult to obtain a polyimide having high characteristics because the molecular weight is low.

  Since a polyimide resin generally has poor solubility in a solvent, it is preferable to impregnate or apply the reinforcing fiber in a state of polyamic acid which is a polyimide precursor. The impregnation method of the polyamic acid is not particularly limited, and may be a continuous type or a batch type. For example, a method of impregnating or coating a reinforcing fiber or fiber fabric with a polyamic acid solution can be mentioned. The impregnation temperature is 0 ° C to 100 ° C, preferably 0 ° C to 80 ° C.

  In the polyamic acid solution, the solid content concentration resulting from the polyamic acid is not limited, but is preferably 5% by mass to 45% by mass, and more preferably 5% by mass to 40% by mass with respect to the total amount of the polyamic acid and the solvent. %, More preferably more than 5% by mass to 30% by mass. When the solid content concentration is lower than 5% by mass, handling during use may be deteriorated, and when it is higher than 45% by mass, the fluidity of the solution may be lost. The solution viscosity at 30 ° C. is not limited, but is preferably 1000 Pa · s or less, more preferably 0.5 to 500 Pa · s, still more preferably 1 to 300 Pa · s, and particularly preferably 2 to 200 Pa · s. Is preferable in handling.

  The application of the polyamic acid that gives the thermoplastic polyimide resin that forms the surface layer is the stage before the removal of the solvent and imidization of the uncured core layer impregnated with the polyamic acid that gives the sheet-like reinforcing fiber the high heat-resistant polyimide resin It is preferable to carry out with. For example, it is preferable to apply the polyamic acid when the heat treatment temperature of the uncured core layer is less than 200 ° C.

  The content of the matrix resin in the composite material of the present invention is 20 to 90% by mass, preferably 30 to 50% by mass. If the content of the matrix resin is less than 20% by mass, it is difficult to obtain a composite material having few pores, and if it exceeds 90% by mass, it is difficult to obtain a uniform composite material.

  The thickness of the core layer in the composite material of the present invention is preferably 5 to 300 μm, and more preferably 20 to 200 μm. Moreover, it is preferable that the thickness of a surface layer is 0.5-30 micrometers, and it is more preferable that it is 1-20 micrometers. When surface layers are formed on both surfaces of the core layer, the thickness of each surface layer may be the same or different.

  Examples of reinforcing fibers that can be used in the present invention include glass fibers, PAN-based carbon fibers, pitch-based carbon fibers, organic fibers, ceramic fibers, alumina fibers, and silicon carbide fibers. Two or more of these fibers can be used in combination. In addition to being used as a sheet-like form aligned in one direction, they can also be used as a woven fabric. These fibers may be subjected to known surface treatment and sizing treatment.

The composite material of the present invention can be produced, for example, as follows.
(1) A sheet-like reinforcing fiber such as a carbon fiber fabric or a carbon fiber spread yarn is impregnated with a polyamic acid solution that gives a high heat-resistant polyimide resin.
(2) Dry at a temperature at which imidization does not proceed excessively. For example, it is dried at 100 to 150 ° C. for 10 to 120 minutes.
(3) A prepreg is prepared by applying a polyamic acid solution that gives a thermoplastic polyimide resin to one side or both sides of the obtained uncured core layer.
(4) The prepreg is heated to remove the solvent and imidize and cure. For example, after heating at 100 to 150 ° C. for 10 to 30 minutes, the temperature is continuously or stepwise raised to 350 to 450 ° C., thereby removing the solvent and completing imidization. The heat treatment can be performed using a known apparatus such as a hot air furnace or an infrared heating furnace.

  A laminated molded body is obtained by laminating the fiber-reinforced polyimide resin composite material of the present invention and heating and molding it under pressure. The molding method is not particularly limited, and examples thereof include sheet winding molding, autoclave molding, and hot press molding. The final heating temperature is preferably 30 ° C. or higher and 420 ° C. or lower than the glass transition temperature of the thermoplastic polyimide resin.

  EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples, but the present invention is not limited to these examples.

A method for measuring the characteristics used in the following examples is shown below.
<Concentration of solid content>
The sample solution (whose mass is w ₁ ) was heat-treated in a hot air dryer at 120 ° C. for 10 minutes, 250 ° C. for 10 minutes, and then 350 ° C. for 30 minutes. ₂ ). Solid content concentration [mass%] was computed by the following formula.
Solid content concentration [% by mass] = (w ₂ / w ₁ ) × 100
<Logarithmic viscosity>
The sample solution was 0.5 g / dl based on the solid content concentration (solvent is N-methyl-2-pyrrolidone, N, N-dimethylacetamide for Examples a1-2, a2-2, and a5-1) Diluted to This diluted solution was added to Cannon Fenceke No. The flow-down time (T ₁ ) was measured using 100. The logarithmic viscosity was calculated from the following equation using the flow time (T ₀ ) of blank water.
Logarithmic viscosity = {ln (T ₁ / T ₀ )} / 0.5
<Solution viscosity (rotational viscosity)>
It measured at 30 degreeC using the Tokimec E-type viscosity meter.
<Delamination strength of laminated molded body>
Measurement was performed at a width of 10 mm and a crosshead speed of 50 mm / min by a 90-degree peel test described in JIS K6854-1.
<Measurement of dimensional change rate when the temperature is raised under a constant load>
A sample sampled to a length of 15 mm / width of 3 mm was subjected to thermomechanical analysis in a tensile mode, a load of 4 gf, and a heating rate of 20 ° C./min using a Seiko Instruments SS6100, and calculated from a TMA curve from 50 ° C. to 400 ° C. .

The abbreviations of the compounds used in the following examples are described.
a-BPDA: 2,3 ′, 3,4′-biphenyltetracarboxylic dianhydride s-BPDA: 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride PPD: p-phenylenediamine ODA: 4,4′-Diaminodiphenyl ether TPE-R: 1,3-bis (4-aminophenoxy) benzene BAPP: 2,2-bis [4- (4-aminophenoxy) phenyl] propane NMP: N-methyl-2- Pyrrolidone DMAc: N, N-dimethylacetamide

[Example 1]
[Example 1]
(а1-1) Polymerization 1
To a 500 mL glass reaction vessel equipped with a stirrer and a nitrogen gas inlet / outlet tube, 396 g of NMP was added as a solvent, 40.05 g (0.20 mol) of ODA was added thereto, and 50 ° C. for 1 hour. Stir and dissolve. To this solution, 58.84 g (0.20 mol) of s-BPDA was added and stirred at 50 ° C. for 3 hours to obtain a solid content concentration of 18.3% by mass, a solution viscosity of 10.0 Pa · s, and a logarithmic viscosity of 0.68. A polyamic acid solution was obtained.
(а1-2) Polymerization 2
To a 500 mL glass reaction vessel equipped with a stirrer and a nitrogen gas inlet / outlet tube, 401 g of DMAc was added as a solvent, 43.85 g (0.15 mol) of TPE-R, and a-BPDA 8.83 g (0.03 mol) and 35.31 g (0.12 mol) of s-BPDA were added and stirred at 40 ° C. for 3 hours to obtain a solid content concentration of 16.9% by mass and a solution viscosity of 80.0 Pa ·. s, a polyamic acid solution having a logarithmic viscosity of 0.3 was obtained.

(b1) Impregnation, drying and imidization
The polyamic acid solution obtained in (a1-1) was impregnated into a carbon fiber spread yarn (SIGRAFIL CC-30 manufactured by SGL Carbon Co., Ltd.) and dried by heating at 120 ° C. for 30 minutes. Thereafter, the polyamic acid solution obtained in (a1-2) was applied to one side and dried by heating at 120 ° C. for 12 minutes, and the reverse side was similarly coated with the polyamic acid solution obtained in (а1-2) to 120 Heat-dry at 12 ° C. for 12 minutes. Heat the resulting uncured composite material at 150 ° C for 2 minutes, 180 ° C for 2 minutes, 210 ° C for 2 minutes, 240 ° C for 2 minutes, 270 ° C for 2 minutes, 300 ° C for 2 minutes, 340 ° C for 2 minutes After drying, imidization and removal of volatile matter were performed to obtain a fiber reinforced polyimide composite material. The resin content of this composite material was 39% by mass.

(c1) Adhesion test
Two laminated fiber reinforced polyimide composite materials obtained in (b1) were superposed and thermocompression bonded at a heating temperature of 320 ° C., a pressure of 1 MPa, and a pressure bonding time of 5 minutes, thereby producing a laminated molded body. As a result of measuring the peel strength of this laminated molded body by the above method, the peel strength was 1.0 N / mm.

(D1) Measurement of dimensional change rate when temperature is raised under a constant load Four fiber reinforced polyimide composite materials obtained in (b1) are superposed so that the fiber directions are the same, and the heating temperature is 320 ° C. A laminated molded body was produced by thermocompression bonding at a pressure of 1 MPa and a pressure bonding time of 5 minutes. The obtained laminated molded body was cut out so that the length direction was perpendicular to the fiber direction and used as a measurement sample. As a result of measuring the dimensional change rate when this sample was heated under a constant load by the above method, the dimensional change rate was 3.7%. The evaluation results are shown in Table 1.

[Example 2]
(а2-1) Polymerization 1
To a 500 mL glass reaction vessel equipped with a stirrer and a nitrogen gas inlet / outlet tube, 402 g of NMP was added as a solvent, and 27.04 g (0.25 mol) of PPD was added thereto, and then at 50 ° C. for 1 hour. Stir and dissolve. To this solution, 73.56 g (0.25 mol) of s-BPDA was added and stirred at 50 ° C. for 3 hours to obtain a solid content concentration of 18.5% by mass, a solution viscosity of 9.5 Pa · s, and a logarithmic viscosity of 0.75. A polyamic acid solution was obtained.
(а2-2) Polymerization 2
To a 500 mL glass reaction vessel equipped with a stirrer and a nitrogen gas inlet / outlet tube, 401 g of DMAc was added as a solvent, 43.85 g (0.15 mol) of TPE-R, and a-BPDA 8.83 g (0.03 mol) and 35.31 g (0.12 mol) of s-BPDA were added and stirred at 40 ° C. for 3 hours to obtain a solid content concentration of 16.9% by mass and a solution viscosity of 80.0 Pa ·. s, a polyamic acid solution having a logarithmic viscosity of 0.3 was obtained.

(b2) Impregnation, drying and imidization
The polyamic acid solution obtained in (a2-1) was impregnated into a carbon fiber spread yarn (SIGRAFIL CC-30 manufactured by SGL Carbon Co., Ltd.) and dried by heating at 120 ° C. for 60 minutes. Thereafter, the polyamic acid solution obtained in (a-2) was applied to one side and dried by heating at 120 ° C. for 12 minutes, and the reverse side was similarly coated with the polyamic acid solution obtained in (а2-2). Heat-dry at 12 ° C. for 12 minutes. The resulting uncured composite material was 150 ° C. for 2 minutes, 180 ° C. for 2 minutes, 210 ° C. for 2 minutes, 240 ° C. for 2 minutes, 270 ° C. for 2 minutes, 300 ° C. for 2 minutes, 340 ° C. for 2 minutes, The mixture was heated and dried at 370 ° C. and at 400 ° C. for 2 minutes to perform imidization and removal of volatile components to obtain a fiber-reinforced polyimide composite material. The resin content of this composite material was 39% by mass.

(c2) Adhesion test
Two pieces of the fiber reinforced polyimide composite material obtained in (b2) were superposed and subjected to thermocompression bonding at a heating temperature of 320 ° C., a compression pressure of 1 MPa, and a compression time of 5 minutes, thereby producing a laminated molded body. As a result of measuring the peel strength of this laminated molded body by the above method, the peel strength was 1.0 N / mm.

(D2) Measurement of dimensional change rate when temperature is raised under a constant load Four fiber reinforced polyimide composite materials obtained in (b2) are superposed so that the fiber directions are the same direction, heating temperature is 320 ° C., and pressure is pressed. A laminated compact was produced by thermocompression bonding at 1 MPa and a pressure bonding time of 5 minutes. The obtained laminated molded body was cut out so that the length direction was perpendicular to the fiber direction and used as a measurement sample. As a result of measuring the dimensional change rate when this sample was heated under a constant load by the above method, the dimensional change rate was 2.9%. The evaluation results are shown in Table 1.

[Comparative Example 1]
(а3-1) Polymerization To a 500 mL glass reaction vessel equipped with a stirrer and a nitrogen gas introduction / discharge tube, 396 g of NMP was added as a solvent, and 40.05 g (0.20 mol) of ODA was added thereto. The mixture was stirred at 50 ° C. for 1 hour to dissolve. To this solution, 58.84 g (0.20 mol) of s-BPDA was added and stirred at 50 ° C. for 3 hours to obtain a solid content concentration of 18.3% by mass, a solution viscosity of 10.0 Pa · s, and a logarithmic viscosity of 0.68. A polyamic acid solution was obtained.

(b3) Impregnation, drying and imidization
The polyamic acid solution obtained in (a3-1) is impregnated into a carbon fiber spread yarn (SIGRAFIL CC-30 manufactured by SGL Carbon Co., Ltd.), 30 minutes at 120 ° C, 2 minutes at 150 ° C, and 2 at 180 ° C. 2 minutes at 210 ° C, 2 minutes at 240 ° C, 2 minutes at 270 ° C, 2 minutes at 300 ° C, 2 minutes at 340 ° C, imidization and removal of volatile matter, fiber reinforced polyimide composite material Got. The resin content of this composite material was 36% by mass.

(c3) Adhesion test
Two pieces of the fiber reinforced polyimide composite material obtained in (b3) were superposed and subjected to thermocompression bonding at a heating temperature of 320 ° C., a pressure bonding pressure of 1 MPa, and a pressure bonding time of 5 minutes, thereby producing a laminated molded body. As a result of measuring the peel strength of this laminated molded body by the above method, the peel strength was 0.1 N / mm.

(D3) Measurement of dimensional change rate when temperature was raised under a constant load Sample preparation was attempted, but the peel strength of the laminated molded body was low, and a good sample could not be obtained. The evaluation results are shown in Table 1.

[Comparative Example 2]
(а4-1) Polymerization To a glass reaction vessel having an internal volume of 500 mL equipped with a stirrer and a nitrogen gas inlet / outlet tube, 402 g of NMP was added as a solvent, and 27.04 g (0.25 mol) of PPD was added thereto. The mixture was stirred at 50 ° C. for 1 hour to dissolve. To this solution, 73.56 g (0.25 mol) of s-BPDA was added and stirred at 50 ° C. for 3 hours to obtain a solid content concentration of 18.5% by mass, a solution viscosity of 9.5 Pa · s, and a logarithmic viscosity of 0.75. Obtained a polyamic acid solution

(b4) Impregnation, drying and imidization
The polyamic acid solution obtained in (a4-1) was impregnated into a carbon fiber spread yarn (SIGRAFIL CC-30 manufactured by SGL Carbon Co., Ltd.), 120 minutes at 60 ° C, 2 minutes at 150 ° C, 2 at 180 ° C. 2 minutes at 210 ° C, 2 minutes at 240 ° C, 2 minutes at 270 ° C, 2 minutes at 300 ° C, 2 minutes at 340 ° C, 2 minutes at 370 ° C, 2 minutes at 400 ° C, imidization and volatilization The fiber reinforced polyimide composite material was obtained. The resin content of this composite material was 36% by mass.

(c4) Adhesion test
Although two fiber reinforced polyimide composite materials obtained in (b4) were stacked and thermocompression bonded at a heating temperature of 320 ° C., a compression pressure of 1 MPa, and a compression time of 5 minutes, an attempt was made to produce a laminated molded body. There wasn't. The evaluation results are shown in Table 1.

[Comparative Example 3]
(а5-1) Into a 500 mL glass reaction vessel equipped with a polymerization stirrer and a nitrogen gas inlet / outlet tube was added 401 g of DMAc as a solvent, and 43.85 g (0.15 mol) of TPE-R was added thereto. ), 8.83 g (0.03 mol) of a-BPDA and 35.31 g (0.12 mol) of s-BPDA were added and stirred at 40 ° C. for 3 hours to obtain a solid concentration of 16.9% by mass, A polyamic acid solution having a solution viscosity of 80.0 Pa · s and a logarithmic viscosity of 0.3 was obtained.

(b5) Impregnation, drying and imidization
The polyamic acid solution obtained in (a5-1) is impregnated into a carbon fiber spread yarn (SIGRAFIL CC-30 manufactured by SGL Carbon), 12 minutes at 120 ° C, 2 minutes at 150 ° C, and 2 at 180 ° C. 2 minutes at 210 ° C, 2 minutes at 240 ° C, 2 minutes at 270 ° C, 2 minutes at 300 ° C, 2 minutes at 340 ° C, imidization and removal of volatile matter, fiber reinforced polyimide composite material Got. The resin content of this composite material was 36% by mass.

(c5) Adhesion test
Two pieces of the fiber reinforced polyimide composite material obtained in (b5) were superposed and subjected to thermocompression bonding at a heating temperature of 320 ° C., a compression pressure of 1 MPa, and a compression time of 5 minutes, thereby producing a laminated molded body. As a result of measuring the peel strength of this laminated molded body by the above method, the peel strength was 0.9 N / mm.

(D5) Measurement of dimensional change rate when temperature is raised under a constant load Four fiber reinforced polyimide composite materials obtained in (b5) are superposed so that the fiber directions are the same direction, heating temperature is 320 ° C., and pressure is pressed. A laminated compact was produced by thermocompression bonding at 1 MPa and a pressure bonding time of 5 minutes. The obtained laminated molded body was cut out so that the length direction was perpendicular to the fiber direction and used as a measurement sample. The dimensional change rate when the temperature of the sample was raised under a constant load was measured by the above method, but the dimensional change exceeded the measuring range during the temperature elevation and could not be measured. The evaluation results are shown in Table 1.

Claims (7)

Fiber reinforcement characterized by having a core layer in which a sheet-like reinforcing fiber is impregnated with a polyimide resin represented by the following chemical formula (1) and a surface layer made of a thermoplastic polyimide resin represented by the following chemical formula (2) Polyimide composite material.

In chemical formula (1),
A ¹ is a group selected from the group consisting of a tetravalent phenyl group and a biphenyl group, and B ¹ is a group selected from the group consisting of a divalent phenyl group and a diphenyl ether group.

In chemical formula (2),
A ² is a group selected from the group consisting of a tetravalent phenyl group and a biphenyl group, and B ² is a divalent group of which 50 mol% or more is represented by the following chemical formula (3).

In chemical formula (3),
R is O, C (CH ₃ ) ₂ , CH ₂ , SO ₂ , S, or a direct bond, R in each bond may be the same or different, and m is an integer of 1 to 4. A ¹ in chemical formula (1) is a tetravalent group in which 90 mol% or more thereof is obtained by removing a carboxyl group from 3,3 ′, 4,4′-biphenyltetracarboxylic acid, and A ² in chemical formula (2) is The fiber reinforced polyimide composite material according to claim 1, wherein 50 mol% or more thereof is a tetravalent group obtained by removing a carboxyl group from 3,3 ', 4,4'-biphenyltetracarboxylic acid. B ² in the chemical formula (2) is 50 mol% or more of 1,3-bis (4-aminophenoxy) benzene, 1,4-bis (4-aminophenoxy) benzene, 2,2-bis [4- ( Amino group is removed from a diamine selected from the group consisting of 4-aminophenoxy) phenyl] propane, 4,4′-bis (4-aminophenoxy) biphenyl, and bis [4- (4-aminophenoxy) phenyl] sulfone The fiber-reinforced polyimide composite material according to claim 1, wherein the fiber-reinforced polyimide composite material is a divalent group. A laminated molded body obtained by laminating the fiber-reinforced polyimide composite material according to any one of claims 1 to 3 and heating and molding it under pressure. A fiber characterized by impregnating a reinforcing fiber with a polyamic acid represented by the following chemical formula (4), creating a prepreg coated with the polyamic acid represented by the following chemical formula (5) on the surface, and curing the prepreg. A method for producing a reinforced polyimide composite material.

In chemical formula (4),
A ¹ is a group selected from the group consisting of a tetravalent phenyl group and a biphenyl group, and B ¹ is a group selected from the group consisting of a divalent phenyl group and a diphenyl ether group.

In chemical formula (5),
A ² is a group selected from the group consisting of a tetravalent phenyl group and a biphenyl group, and B ² is a divalent group of which 50 mol% or more is represented by the following chemical formula (3).

In chemical formula (3),
R is O, C (CH ₃ ) ₂ , CH ₂ , SO ₂ , S, or a direct bond, R in each bond may be the same or different, and m is an integer of 1 to 4. A ¹ in chemical formula (4) is a tetravalent group in which 90 mol% or more thereof is obtained by removing a carboxyl group from 3,3 ′, 4,4′-biphenyltetracarboxylic acid, and A ² in chemical formula (5) is The fiber reinforced polyimide composite material according to claim 5, wherein 50 mol% or more thereof is a tetravalent group obtained by removing a carboxyl group from 3,3 ′, 4,4′-biphenyltetracarboxylic acid. Production method. B ² in the chemical formula (5) is 50 mol% or more of 1,3-bis (4-aminophenoxy) benzene, 1,4-bis (4-aminophenoxy) benzene, 2,2-bis [4- ( Amino group is removed from a diamine selected from the group consisting of 4-aminophenoxy) phenyl] propane, 4,4′-bis (4-aminophenoxy) biphenyl, and bis [4- (4-aminophenoxy) phenyl] sulfone The method for producing a fiber-reinforced polyimide composite material according to claim 5, wherein the fiber-reinforced polyimide composite material is a divalent group.