JPH03160035A - Prepreg sheet - Google Patents

Abstract

PURPOSE:To prepare a prepreg sheet having a tack and drape by impregnating a fibrous reinforcement with a paste comprising a soln. of a polyamic acid and polyimide resin powders dispersed therein. CONSTITUTION:A tetracarboxylic acid dianhydride is reacted with a diamine in an org. solvent to give a soln. of a polyamic acid having repeating units of formula I [wherein R1 is a divalent group selected from the group consisting of a 2C or higher (cyclic) aliph. group, monocyclic arom. group, condensed polycyclic arom. group, noncondensed polycyclic arom. group wherein arom. groups are linked together by a crosslinking member, and heterocyclic group; R2 is a tetravalent group selected from the group consisting of a (cyclic) aliph. group, monocyclic arom. group, condensed polycyclic arom. group, and noncondensed polycyclic arom. group wherein arom. groups are linked together by a crosslinking member; and X is H, alkyl, or aryl]. The polyamic acid in the soln. is imidized, and a precipitated powder is separated by filtration to give a polyimide resin powder having repeating units of formula II (wherein R3 is R1; and R4 is R2). The polyimide resin powder is dispersed in the soln. of the polyamic acid to give a paste, with which a fibrous reinforcement is impregnated.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a brypreg sheet useful as a heat-resistant adhesive, a heat-resistant composite material, and the like.

[Conventional technology]

In the field of electronics, aerospace equipment, etc.
There is a desire for higher performance and lighter weight of various materials, and there is a demand for materials with even better high-temperature properties.

Conventionally, epoxy resins, modified epoxy resins, and the like have been used as materials for structural adhesives or brippregs for laminated molded bodies, but these resins have poor heat resistance.

On the other hand, polyimide resin is known as a resin with excellent heat resistance. Moreover, polyimide resin has mechanical properties, heat resistance,
It is known to have excellent properties such as insulation properties.

However, since polyimide resin has excellent heat resistance and solvent resistance, it is extremely difficult to arbitrarily control the amount of resin adhered to the fibrous reinforcing material and to adhere it uniformly.

For example, when heating and melting a polyimide resin to impregnate it into a fibrous reinforcing material, the melt viscosity is extremely high within a range that does not impair the physical properties of the resin, so it is difficult to adhere uniformly with good productivity.

It is difficult to dissolve the polyimide resin in a solvent and impregnate it into a fibrous reinforcing material because there is no suitable solvent that dissolves the polyimide resin.

As a method to overcome these difficulties, a method is proposed in which polyimide resin powder is applied to a fiber-like reinforcing material, and then heated to a temperature above the softening point of the polyimide resin to melt it and impregnate it (Japanese Unexamined Patent Application Publication No. 1983-1992).
No. 98744), after applying an organic solvent solution of polyamic acid, which is a precursor of polyimide resin, to the fibrous reinforcement material,
A method of converting polyamic acid into polyimide resin by heating, removing the organic solvent, and dehydrating cyclization reaction (Japanese Unexamined Patent Publication No. 61
-235437) has been proposed. However, in the former method, the polyimide resin powder attached to the fiber-like reinforcing material easily falls off in a dry state, making it difficult to control the amount of resin that affects the properties of the final laminate, especially the mechanical properties. Even if the amount of resin is better controlled, the pre-reg after being heated and melted and impregnated will be rigid and tack-free. 1. In the latter method, the amount of resin adhered to the coarse reinforcing material largely depends on the viscosity of the polyamic acid solution, but the viscosity of the polyamic acid solution changes in a complex manner depending on the polyamic acid concentration, polyamic acid molecular weight, and solvent. However, it is difficult to deposit the desired amount of polyamic acid with the required molecular weight.

[Problem to be solved by the invention]

The present invention has been made based on the above-mentioned viewpoints, and an object of the present invention is to provide a new tacky bripreg impregnated with polyimide resin, which has been difficult to achieve in the past.

[Means to solve the problem]

That is, the gist of the present invention is to impregnate a fibrous reinforcing material with a paste consisting of an organic solvent solution of polyamic acid having a repeating unit of formula (1) and a polyimide resin powder having a repeating unit of formula (2). It's on the buri preg sheet.

[In the formula, R1 and R. Para-1 or different aliphatic groups having 2 or more carbon atoms, cycloaliphatic groups, monocyclic aromatic groups, condensed polycyclic aromatic groups, aromatic groups interconnected by a bridge member represents a divalent group selected from the group consisting of a non-fused polycyclic aromatic group and a heterocyclic group, R and R are the same or different aliphatic groups having 2 or more carbon atoms, From the group consisting of a cycloaliphatic group, a monocyclic aromatic group, a fused polycyclic aromatic group, a non-fused polycyclic aromatic group in which aromatics are interconnected by a bridge member, and a heterocyclic group Represents a selected tetravalent group, XFi represents a group selected from the group consisting of a hydrogen atom, an alkyl group, and an aryl group. ] The present invention will be specifically explained below.

The polyamic acid of the present invention can be synthesized by a known method. Generally, it is obtained by reacting detracarboxylic dianhydride and diamine in an organic solvent. Specifically, the diamine is synthesized by slowly adding a diamine to an organic solvent in which a tetracarboxylic dianhydride is dissolved or dispersed under a stream of dry nitrogen.

Synthesis is carried out by gradually adding tetracarboxylic dianhydride to a 1-tapa diamine solution.

Examples of tetracarboxylic dianhydrides are as follows.

Biromellitic dianhydride, 5.3,' 4. 4'-penzophenonetetracarboxylic dianhydride, 2,2:s,
3'-benzophenonetetracarboxylic acid dianhydride 71, x,
hl4. at-biphenyltetracarboxylic dianhydride, 2. 2: s, 3'-biphenyltetracarboxylic dianhydride, bis(Otsu 3-dicarboxylphenyl)
Methanihydride, bis(dicarpoxyphenyl)
Methanihydride, 2,2-his(h4-dicarboxylphenyl)propanihydride, 2.2-bis(2.5-
dicarboxylphenyl) propanhydride, bis(4-dicarboxyl phenyl) ether dianhydride, his(2,5-dicarboxyl phenyl) ether dianhydride, bis(S,4-dicarboxylphenyl) sulfone dianhydride bis(2,5-dicarboxylphenyl)sulfonhydride, bis(4-dicarboxylphenyl)
1 phenylphosphonate dianhydride, bis(!ll4-dicarboxylphenyl) 1 phenylphosphine oxide dianhydride, N,N-(5.4-dicarboxylphenyl) 1N-methylamine dianhydride, bis(54-dicarpoquinruphenyl)-diethylsilanim water e+,
Bis(5.4-')carpoxylphenyl)-tetramethyldisiloxane dianhydride, 3, 3,' 4. 4'
-tetracarpoxypenzoyloxybenzene dianhydride, 2.447-naphthalenetetracarboxylic dianhydride,
1, 4, 5. 8-Naphthalenetetracarboxylic dianhydride, 1, 2, 5. 6-naphthalenetetracarboxylic dianhydride, 1, aq, 1o-phenanthrene detracarboxylic dianhydride, 3,4,9.10-berylenetetracarboxylic dianhydride, 2,3, 4.5-thiophenedetracarboxylic dianhydride, 2, melon 5, 6-pyrazinetetracarboxylic dianhydride, 2,45.6-pyridinetetracarboxylic dianhydride, 1, otome 4- Cyclobentanetetracarboxylic dianhydride and the like. Tetracarboxylic dianhydrides can be used alone or in combination of two or more.

Examples of diamine compounds include the following.

0-phenylenediamine, m-phenylenediamine, p
-phenylenediamine, 2,4-diaminotoluene, 1
．． 4-diamino-2-methoxybenzene, 2.5-diaminoxylene, 1.3-diamino-4-chlorobenzene, 1,4-diamino-2.5-dichlorobenzene, 1.
4-diamino-2-promobenzene, 1,3-diamino-4-isobrobylbenzene, 2,2-bis(4-aminophenyl)propane, 3'-diaminodiphenylmethane, 4,4'-diaminodiphenylmethane , 54'-
Diaminodiphenyl methane, 3'-diaminodiphenyl ether, 4.4'-diaminodiphenyl ether,
s,4'-s) aminodiphenyl ether, 3'-diaminodiphenyl thioether, 4,4'-diaminodiphenyl thioether, 4'-diaminodiphenyl thioether, 3'-diaminodiphenyl sulfone, 4
．． 4'-diaminodiphenylsulfone, 54'-diaminodiphenylsulfone x, sl-cyaminobenzophenone, 4.4'-diaminobenzophenone, he4
'-diaminopenzophenone, 1,8-diaminonaphthalene, 1,5-diaminonaphthalene, 1,5-diaminanthraquinone, and the like. Diamine compounds can be used alone or in combination of two or more.

In order to adjust the molecular weight of polyamic acid or polyimide, a so-called end capping agent may be used. Phthalic anhydride, aniline, etc. are used as such end capping agents.

The organic solvent used is N,N-dimethylformamide,
These include M,N-dimethylacetamide, N-methyl-2-pyrrolidone, dimethyl sulfoxide, diethylene glycol dimethyl ether, and m-cresol. These can be used alone or in combination of two or more. The resulting polyamic acid preferably has a reduced viscosity of about 2 to 2 dL/f from the viewpoint of film formation as a paste, handling of the solution, mechanical strength and heat resistance of the polyimide resin after imidization, etc. Yes.

Next, a portion of the obtained polyamic acid solution, or a polyamic acid solution separately combined in the same manner as above, is dehydrated and imidized. However, the polyimide resin powder to be dispersed in the paste is preferably one that is insoluble or swells in the polyamic acid solvent.

Dehydration and imidization of a polyamic acid solution is carried out, for example, as follows. That is, the imidizing agent is gradually added to the polyamic acid solution under a nitrogen stream and reacted. Conversely, a polyamic acid solution may be added to the imidizing agent.

Examples of the imidizing agent include acetic anhydride, probionic anhydride, isobutyric anhydride, butyric anhydride, and the like. These may be used alone or in combination of two or more.

The amount of imidizing agent added is 1 to 2 equivalents based on the carboxyl group in the polyamic acid, and the addition amount is -10 to 150
It is preferable to use 6C.

It is also possible to add an imidization catalyst at the same time. Tertiary amines are used as such catalysts. Examples include trimethylamine, triethylamine, triptylamine, pyridine, α-picoline, β-picoline, γ-
Examples include picoline. The amount of imidization catalyst added is 0.2 to 1 equivalent relative to the carboxyl group in the polyamic acid.

Specifically, the process of obtaining polyimide resin powder from a polyamic acid solution is performed as follows.

While stirring the polyamic acid solution under a nitrogen stream, the imidizing agent is gradually added, and if the stirring is continued even after the addition is complete, polyimide resin powder is precipitated. This is filtered, washed with water and an organic solvent, and then heated and dried to obtain polyimide resin powder. This BoIJ imide resin powder is often 5 to 40 μm thick.
Almost spherical fine particles of 100% are combined to form a maximum particle size of about 60 μm. These associated particles can be easily ground with a grinder to form a polyimide resin powder in the form of substantially spherical particles having a particle diameter of 5 to 40 μm.

The average particle diameter of the polyimide resin powder used in the present invention is 3
Desirably, the particle size is 0 μn1 or less and the maximum particle diameter is 40, um or less. Considering impregnation into the FII fibrous reinforcing material, it is preferable that the average particle size is 10 μm or less and the maximum particle size is 20 μm or less.

The paste-like material used in the present invention refers to a material obtained by mixing and dispersing polyimide resin powder in a polyamic acid solution. The amount of polyimide resin powder used is 5 to 50% for the paste-like material.
It is within the range of 50% by weight. If the amount used is less than 5 weight i4, the effect of powder addition will be significantly impaired, and if the amount used exceeds 50 weight i4, the fluidity of the paste will be significantly impaired.

The polyamic acid concentration in the polyamic acid solution was 5 to 5.
0-fold i1cIi, preferably 10 to 40-fold i1cIi.

A preferred method for mixing and dispersing the polyimide resin powder in the polyamic acid solution is a mixing device used in the field of paints and coatings, such as a three-roll, double-arm kneader, etc.

The method for uniformly applying the paste to the m, m-shaped reinforcing material may be any method as long as it can apply a paste with a uniform thickness, and a doctor blade, bar coater, etc. can be used.

In accordance with the present invention, a fibrous reinforcing material is placed on a release paper by applying a paste uniformly with a doctor blade, and the material is pressed to impregnate the material to obtain a buripreg sheet. The fibrous reinforcing material is glass fiber, carbon fiber, wholly aromatic polyamide fiber, or the like.

〔Effect of the invention〕

Since the paste material of the present invention impregnates the inside of the fibrous reinforcing material, there is no need to further impregnate it by heating and melting it, or to prevent the resin powder from falling off. It has sex and tack.

〔Example The present invention will be explained below with reference to Examples and Comparative Examples.

"Reduced viscosity" ηinh is calculated using N,N-dimethylformamide as a solvent, and the sample concentration O is Q. It was calculated from the viscosity η measured at 35°C using the following formula as 5r/at. However, η. is the viscosity of N,N-dimethylformamide (35°C)
It is.

η, nh (1/0) 1n (η/η.) The "average particle diameter" of the resin powder is 200
It is the volume average particle diameter measured with a μm aperture tube.

Example 1 U) Preparation of polyamic acid solution 4,4'-diaminodiphenyl ether (2
00t, 1 mOL) and m-cresol tooor were injected. Keep this at 25℃ and rotate at 400 rpm.
While stirring, proceed to step 5' 4. 4'-Benzophenonetetracarboxylic dianhydride (522f, 1 mot) was added over about 10 minutes, being careful not to increase the temperature. The t&&' 4 4'-benzophenonetetracarboxylic dianhydride remaining in the container was poured into the reaction container with 260 tons of m-cresol. Even after adding the entire amount, the temperature at 25°C is about 20
Stirring was continued for an hour. The reduced viscosity of the obtained polyamic acid was (16 at/t). The polyamic acid solution was stored at 0°C.

(b) Preparation of polyimide resin powder 890 tons of the polyamic acid solution obtained in (a)
and acetic anhydride (204f, 2mol) under a nitrogen stream while stirring at 400 rpm.
t), β-vicolin (253 t, Q.25rnoL
) was added. At this time, the reaction vessel was kept at 25°C.

Even after the addition, when stirring was continued for about 8 hours, yellow polyimide resin powder precipitated.

This polyimide resin powder was filtered, then boiled and washed with methanol, and then heated and dried. The yield of polyimide resin powder was 255f.

The obtained polyimide resin powder was pulverized using a freeze pulverizer, and then passed through a sieve with a 52 μm opening until the maximum particle size was 32 μm.
240 tons of the following polyimide resin powder was obtained.

(c) Preparation of a paste 1 BOf the polyimide resin powder obtained in (b) was added to 540 t of the polyamic acid solution obtained in (a), and
The mixture was kneaded uniformly using a der. This was transferred to a doctor blade, and a paste film (width 15
m, length 2.5 m) was obtained.

Next, make this paste film with a circumference of 1m and a length of 0.7m.
It was pasted on a 5 m drum with the paste side facing up. On top of this, add 3 pieces of carbon fiber (Vyrofil T-1 12K manufactured by Mitsubishi Rayon Co., Ltd.)/cm (Weight: 1 o o
t/m"). Furthermore, it was wound to a thickness of 20 μm.
m polypropylene films were laminated. This was cut open, removed from the drum, and pressed at a pressure of 1 kg/crn to impregnate the paste into the carbon fibers so as not to disturb the fiber direction.

(d) This prepreg is laminated on a certain shaped metal plate of the laminate, and a mold release agent (
Air-Tech Release-1 1◆100
) coated with polyimide 7 film (Kapton, manufactured by DuPont) having fine pores. Further, four sheets of glass cloth were placed on top of this and covered with a polyimide film to seal the space between them and the metal plate.

Next, this was transferred to an autoclave, and the temperature was reduced to 340°C while reducing the pressure between the top film and the bottom metal plate.
℃ and the pressure was kept at 20 kg/cm'' for about 1 hour. After lowering the temperature and pressure, it was taken out.

The carbon RQ fiber content of this molded body was 58 by volume, and the tensile strength was 1.4. 0 k2/1 bending strength is 15.5
Yu/wm”.

Claims (1)

[Claims] A prepreg obtained by impregnating a fibrous reinforcing material with a paste consisting of an organic solvent solution of polyamic acid having a repeating unit of formula (1) and a polyimide resin powder having a repeating unit of formula (2). sheet. ▲There are mathematical formulas, chemical formulas, tables, etc.▼...(1) [In the formula, R_1 and R_3 are the same or different aliphatic groups with 2 or more carbon atoms, cycloaliphatic groups, monocyclic aromatic groups, fused polycyclic groups, etc. Represents a divalent group selected from the group consisting of a cyclic aromatic group, a non-fused polycyclic aromatic group in which aromatics are interconnected by a bridge member, and a heterocyclic group, and R_2 and R_4 are the same or Different aliphatic groups having 2 or more carbon atoms, cycloaliphatic groups, monocyclic aromatic groups, fused polycyclic aromatic groups, and non-fused polycyclic aromatic groups in which aromatics are interconnected by a bridge member. represents a tetravalent group selected from the group consisting of groups and heterocyclic groups, and X represents a group selected from the group consisting of hydrogen atoms, alkyl groups and aryl groups. ]