JPS63264351A - Interleaf-containing fiber-reinforced polyimide resin laminate molded product - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention relates to an interleaf-containing fiber-reinforced polyimide resin laminate molded product, more specifically, it contains a polyimide film as an interleaf, and has excellent interlaminar shear strength, bending fracture strength, The present invention relates to a laminated molded product having a large amount of deflection at bending failure, excellent heat resistance, high strength, and high toughness, and is widely applied to aircraft, space industry equipment, etc.

(Prior art and its problems) Fiber-reinforced epoxy resin composite materials have high specific strength and specific modulus, and are therefore widely used in everything from sporting goods to structural materials for aircraft. However, its heat resistance is insufficient, and although the resin has been modified, the results are not satisfactory. On the other hand, polyimide resin is known as a resin with excellent heat resistance, and its use as a matrix for composite materials is being considered. However, condensed polyimide resins have a high melting temperature, require almost no solvent, and cannot be handled in the same way as epoxy resins. For this reason, methods using addition-type polyimide resins have been considered, but although the moldability has been improved, the heat resistance of the resulting laminate molded products has significantly decreased, making it impossible to fully utilize the original properties of polyimide resins. Not yet. For this reason, a method has been adopted in which a base material is impregnated with polyamic acid, which is a precursor of a condensed polyimide resin, and then these are laminated, heated and pressurized to imidize, and a laminate is manufactured. However, in this case, water generated during imidization causes voids to occur in the laminate, resulting in a decrease in physical properties. In order to solve these problems, Japanese Patent Application Laid-open No. 61-98741 and Japanese Patent Application Laid-Open No. 98742
Publication No. 98744, Publication No. 235437,
Publication No. 250031, Publication No. 277441, Publication No. 27
There is a method using a heat-sealable polyimide resin as a main component, as disclosed in Japanese Patent No. 7442 and the like. However, in composite materials obtained by these methods, the adhesive strength between the laminated layers is weak and the interlaminar shear strength is significantly lower, and the bending fracture strength, amount of deflection at bending fracture, and tensile strength are also reduced, making it difficult to put them into practical use. It is.

(Object of the Invention) An object of the present invention is to provide a fiber-reinforced polyimide resin laminate molded product having excellent mechanical strength such as interlaminar shear strength and bending fracture strength, high toughness, and excellent heat resistance.

(Structure of the Invention) The present invention provides that the glass transition point of the matrix is 250°C to 3.
A fiber-reinforced polyimide resin layer having a temperature of 50°C, a tensile elongation at break of 90% or more, and a glass turning point of 250°C to 3.
It has a laminated structure in which interleaves made of 50t polyimide films are alternately laminated, and the polyimide of the fiber-reinforced polyimide resin layer and the polyimide film of the interleaf are heat-sealed to each other. Contains interleaf! The present invention relates to a fiber-reinforced polyimide resin laminate molded product.

(Preferred Embodiment of the Invention) The interleaf-containing fiber-reinforced polyimide resin laminate molded product of the present invention is obtained by laminating a plurality of fiber-reinforced polyimide resin prepregs and polyimide films as interleaves and then heat-pressing them. In a preferred embodiment of the present invention, first, a tetracarboxylic acid component containing 80 mol% or more of phenyltetracarboxylic acid and a diamine component containing 80 mol% or more of an aromatic diamine having a plurality of benzene rings are mixed in an organic polar solvent. The polyamic acid solution is polymerized in the polyamic acid solution. Next, after impregnating this into a base material, it is desolventized and imidized, and the glass transition point (secondary transition point) of the obtained matrix is 250°C to 350°C, and it can be bonded to a fiber-reinforced polyimide resin prepreg that can be heat-fused. Breaking elongation is 90%
An interleaf-containing taM obtained by fusing and integrating a heat-sealable polyimide film having a glass transition point of 250°C to 350°C and having the above properties without an adhesive layer.
1. This is a reinforced polyimide resin laminate molded product.

Note that the tensile elongation at break is a value measured according to ASTM-D 882-64T. In addition, the glass transition point (secondary transition point) in the present invention is the temperature at which a polymer freezes the molecular micro-Brownian motion and transitions to a glass state, and can be measured by dynamic viscoelasticity measurement, thermal analysis measurement, etc. can do. Furthermore, thermal fusion in the present invention means that when heated to a temperature higher than the glass transition point, significant decomposition does not occur, and fusion occurs under pressure. The biphenyltetracarboxylic acids mentioned here include 3.3', 4
．． 4'-biphenyltetracarboxylic acid, its dianhydride, or lower alkyl ester of the acid, or 2
, 3.3', 4'-biphenyltetracarboxylic acid, its acid dianhydride, or lower alkyl ester of that acid,
Further, a mixture of soft straw can be mentioned.

In the present invention, the biphenyltetracarboxylic acids include 3
．． 3', 4,4'-biphenyltetracarboxylic dianhydride alone, 2,3,3', 4'-biphenyltetracarboxylic dianhydride alone, or a mixture thereof is suitable. Especially 3.3', 4.

When biphenyltetracarboxylic acids containing 4'-biphenyltetracarboxylic dianhydride alone or 80 mol% or more are used, the heat resistance and strength of the resulting laminate molded product, and the interleaf described below It is optimal in terms of adhesive properties, etc.

In addition to the above-mentioned biphenyltetracarboxylic acids, the present invention also uses other aromatic tetracarboxylic acids as the tetracarboxylic acid component, such as pyromellitic acids, benzophenonetetracarboxylic acids, 2,2-bis(3,
4-dicarboxyphenyl)propane, bis(3,4-
Dicarboxyphenyl)methane, bis(3,4-dicarboxyphenyl)phosphine, etc. may be contained in an amount less than about 20 mol%, particularly less than 10 mol%, based on the total amount of the tetracarboxylic acid component.

Examples of the aromatic diamines having a plurality of benzene rings include 4.4'-diaminodiphenyl ether, 3.3'-diaminodiphenyl ether, 3.
．． 3'-dimethyl-4,4'-diaminodiphenyl ether, diphenyl ether diamines such as 3,3'-methoxy-4,4'-diaminodiphenyl ether, 4,4'-diaminodiphenylthioether,
3. Diphenylthioether diamines such as 3'-diaminodiphenylthioether, 4.4'-diaminobenzophenone, benzophenone diamines such as 3,3'-diaminobenzophenone, 4.4'-diaminodiphenylphosphine, 3.3 diphenylphosphine diamines such as ′-diaminodiphenylphosphine,
4.4'-diaminodiphenylmethane, 3.3'-
Examples include diphenylmethane diamines such as diaminodiphenylmethane.

In this invention, the aromatic diamines having a plurality of benzene rings are particularly diphenyl ether diamines alone such as 4,4'-diaminodiphenyl ether, 3,3'-diaminodiphenyl ether, or
Preferred examples include a mixture of 60 mol% or more, especially 80 mol% or more of a diphenyl ether diamine and less than 40 mol%, especially less than 20 mol% of another aromatic diamine having a plurality of benzene rings.

Further, in this invention, as the diamine component, in addition to the above-mentioned aromatic diamines having a plurality of benzene rings,
Other diamines, such as 0-1m-1p-phenylenediamine, may also be present, provided they are less than about 20 mol%, particularly less than 10 mol%, based on the total amount of diamine component.

Tetracarboxylic acids and aromatic diamines as described above are polymerized to form polyamic acids, and this polymerization is usually carried out in an organic solvent. That is, after dissolving both of the above components in an organic solvent, a polymerization reaction is performed. As for polymerization conditions, the temperature is preferably maintained at 0°C to 60°C, particularly 5°C to 50°C, and the time is determined depending on the temperature and the viscosity of the desired polyamic acid. At this time, the organic solvents used include N,N-dimethylformamide, N,
Amide polar solvents such as N-dimethylacetamide, N,N-diethylacetamide, N,N-dimethylmethoxyacetamide, N-methyl-2-pyrrolidone, 1.3
-Dimethyl-2-imidazolidinone, lactam conductors such as N-methylcaprolactam, 1,2-dimethoxyethane, bis(2-methoxyethyl) ether, l,2-
linear or cyclic ethers such as bis(2-methoxyethoxy)ethane, tetrahydrofuran, and 1,4-dioxane; nitrogen-containing heterocyclic compounds such as pyridine and picolines;
Examples include sulfoxides such as dimethyl sulfoxide and dimethyl sulfone, sulfone compounds, urea derivatives such as tetramethylurea, and phosphoric acid amide derivatives such as hexamethylphosphoramide. Moreover, these organic solvents can be used alone or in combination. There is no problem even if a mixture of ffi or more is used.

Such polyamic acid is heated to a temperature of 100° C. to 350° C. to be imidized and becomes polyimide. Note that the removal of the solvent from the polyamic acid solution and the heating for imidization of the polyamic acid may be performed continuously, or the latter half of solvent removal and the first half of imidization may be performed simultaneously. . The polyimide thus obtained has an imidization rate of 9
0% or more, and the logarithmic viscosity of the polymer (50°C,
Concentration; 0.5 g/100 rnl solvent, solvent; measured with p-chlorophenol) is 0.2-7, especially 0.3-5
That's about it. The glass 18 point (secondary transition point) is preferably 250°C to 350°C, more preferably 260°C to 340°C. If the glass transition point of the aromatic polyimide is lower than 250°C, the heat resistance of the resulting laminate molded product will be significantly lowered, and if it is higher than 350°C, molding by heat fusion will be difficult, which is not preferred.

The reinforcing fibers used in the present invention include glass fiber, P
AN-based carbon fiber, pitch-based carbon fiber, aramid fiber, alumina fiber, silicon carbide fiber, and 5
t-Ti-C-0 fiber (Tyranno fiber, manufactured by Ube Industries),
Also, two or more of these fibers can be used in combination.

Moreover, in addition to being used in a form in which these materials are aligned in one direction, they can also be used as a woven fabric. These fibers may be subjected to known surface treatments and sizing treatments.

In addition to the above, various fillers, additives, pigments, etc. may be added to the prepreg in the present invention to the extent that the effects of the present invention are not impaired.

Next, the fiber reinforced polyimide resin prepreg of the present invention is
It is obtained by immersing the above polyamic acid solution into a base material, then removing the solvent and imidizing the base material. The concentration of the polyamic acid solution is 5 to 30% by weight, particularly preferably
It is 10 to 20% by weight. Also, viscosity [rotational viscosity measured at 30°C (measured with a Brookfield rotational viscometer)]
is 0.1 to 200 voices, more preferably 0.5 to 200
It is 150 poise, particularly preferably 1 to 100 poise. There is no particular restriction on the impregnation method, and it may be a continuous method or a batch method. The impregnation temperature is 0°C to 100°C, preferably 0°C to 50°C. Imidization and solvent removal in the present invention are not particularly limited, but for example, from 150°C to 30°C.
This is done by heating in an oven at 00°C.

The time is determined as appropriate depending on the heating pattern. In addition, there are the following methods other than the above. That is, the polyamic acid solution produced as described above is subjected to an imide cyclization reaction in the presence of an appropriate imidizing agent at a temperature of 150 t or less to prepare a phenolic solvent solution of aromatic polyimide, or biphenyl tetra A tetracarboxylic acid component mainly composed of carboxylic acids and an aromatic diamine component mainly composed of aromatic diamines having multiple benzene rings are mixed in a phenolic solvent (e.g. phenol, cresol, monohalogenated phenol). , monohalogenated cresol, etc.) at a high temperature of approximately 150 to 300°C to create a solution of soluble polyimide in a phenolic solvent, which is impregnated into a base material, and then the solvent is removed. There is a method for obtaining fiber-reinforced polyimide resin prepreg.

The interleaf in the present invention has an imide skeleton,
Tensile elongation at break is 70% or more and glass transition point is 25
It is a polyimide film that can be heat-sealed at 0°C to 350°C. Examples of the structural formula of the imide skeleton of a polyimide film having a glass transition point of 250°C to 350°C and which can be heat-sealed include II II u. Must. This is because if the tensile elongation at break is less than 90%, the objective of the present invention, which is to improve the toughness of the laminate molded product, cannot be achieved. As such a polyimide film, a polyimide film having an imide skeleton represented by (
Corbilex R1 (manufactured by Ube Industries, Ltd.) is available.

Such a film is disclosed, for example, in Japanese Patent Application Laid-Open No. 50-1135.
No. 97, No. 55-27326, No. 55-28
It is manufactured by the method disclosed in Japanese Patent No. 822, Japanese Patent No. 55-65227, and the like.

If the glass transition point of the interleaf deviates from the range of 250 DEG C. to 350 DEG C., the adhesion to the polyimide resin of the matrix will be insufficient and the physical properties of the resulting laminate will deteriorate, which is not preferred.

The thickness of the polyimide film is preferably 5 to 40 μm
1, particularly preferably 10 to 30 μm. If it is thinner than 5 μm, it is difficult to manufacture and is economically disadvantageous. Also 40μ
If it is thicker than m, it is difficult to achieve the object of the present invention.

In addition, for the purpose of improving the material properties of the interleaf, about 40% by weight or less of resins, rubbers, whisker powder, shredded fibers, or reinforcing agents may be added to the interleaf as a modifier. be able to.

Further, in order to improve the adhesion between the polyimide resin and the interleaf, it is also possible to treat the surface of the interleaf (for example, corona discharge treatment, matte processing, silane coupling agent treatment, etc.).

Furthermore, for example, if a polyimide film with a large number of holes is used as the interleaf, the toughness is further improved.

Two or more polyimide films of the present invention can also be used in a stacked manner. Next, a plurality of sheets of the fiber-reinforced polyimide resin prepreg obtained as described above and a polyimide film used as an interleaf are alternately laminated to 10°C to 200°C, preferably 20°C to 15°C above the glass transition point.
0t: Welded at high bonding temperature. At this temperature, the matrix polyimide resin and the interleaf must be thermally fused together. Also, the pressure is 10 to 80
0 Kg/cm2 More preferably, 30 to 500 g
/cm2, and the pressurizing time is 0.1 seconds to 2 hours, especially 30
The time period is from seconds to 1.5 hours, more preferably from 1 to 60 minutes. In this way, the prepreg and interleaf can be directly
They are joined together to produce a laminate molded article (FIG. 1) of the present invention. In the present invention, heating and pressurization may be performed by a hot press method, or a plurality of prepregs and interleafs may be preheated if necessary and continuously supplied, and heated by stacking them with a pressing hot roll.・Crimping and bonding may be performed continuously at the same time. In the following examples, polyimide films of the same composition were used for the matrix and the interleaf, but they do not necessarily have to be the same.

(Effects of the invention) The interleaf-containing fiber-reinforced polyimide resin laminate molded product of the present invention has excellent heat resistance, interlaminar shear strength, bending fracture strength,
It has excellent mechanical properties such as the amount of deflection during bending and fracture, and has high toughness.

(Examples of the present invention) Measurements of various physical properties shown in Examples and Comparative Examples are shown below.

(1) Measuring machine: Toyo Baldwin, Tensilon T (2) Bending test = 3-point bending method, span/thickness ratio - 40, crosshead speed 2 mm/min. Temperature 23℃, humidity 50%RH.

(3) Interlaminar shear strength Span /
The thickness ratio was 4 and the crosshead speed was 2 mm/min. Temperature: 23°C, humidity: 50% RH.

Example 1 A cylindrical polymerization tank with an internal volume of 5i, 3.3' and 4.4'
-Biphenyltetracarboxylic dianhydride 294g (1 mol), 4,4'-diaminodiphenyl ether 202
．． 2 g (1 mol) and 1977 g of N-methyl-2-pyrrolidone were charged. This mixture was heated to a reaction temperature of 50°C.
The polymerization reaction was carried out under normal pressure with stirring for 44 hours, and the logarithmic viscosity was 0.68 (30°C, 0.5 g/10 omp).
An aromatic polyamic acid solution was obtained. The solution was then left under reduced pressure (0.01 atm) for 2 hours while maintaining the temperature at 50°C to evaporate and remove free water, resulting in a water content of 1.1% by weight (Karl, Rue). A polyamic acid solution with a value measured by Fischer titration method was obtained. The concentration of this polyamic acid solution is 20% by weight, and the solution viscosity is 48 voids (30% by weight).
The rotational viscosity was measured with a Brookfield rotational viscometer at °C. This solution was applied to a glass woven cloth (wE-tts-
to4, made by Nitto Boseki ■, thickness + 0.10mm, weight:
105g/m2, plain weave) and then heated in a heated oven at 150℃ for 5 minutes, 200℃ for 7 minutes, 250℃ for 9 minutes and finally 350℃ for 7 minutes while removing the solvent. Polyamic acid was imidized. The volume content of 1a of the obtained polyimide prepreg was 60.5%. This prepreg was cut into a size of 90 mm x 260 mm. In addition, polyimide film (Corbilex R
1 tensile elongation at break = 130%, thickness = 25 μm, manufactured by Ube Industries, Ltd.) were cut to the same size. Next, 20 prepreg sheets and 19 polyimide films were alternately laminated. At this time, the prepregs were laminated in the same direction. Then, it was press-molded for 1 hour at 350° C. and under a pressure of 300 Kg/cm 2 . After cooling to 200° C. under pressure, the pressure was released and the mold was demolded.

The resulting composite material has a length of 85 aun and a width of 12 and 7 m.
m bending test piece (1a fiber direction), length 28 mm, width 1
A 2.7 mm glabella shear test piece was cut out in the <ta fiber force direction. using these test pieces. The bending breaking strength, the amount of deflection at bending breaking, and the interlaminar shear strength were measured. The results are shown in Table 1. Example 2 In Example 1, the glass fiber cloth was replaced with carbon fiber cloth, Besphite fiber W-3101 manufactured by Toho Rayon Co., Ltd., thickness 0.
．． A laminate molded product was molded in exactly the same manner as in Example 1, except that 8 sheets of prepreg and 7 sheets of polyimide film were alternately laminated instead of 25 mm, weight 200 gem", flat 1 Alt), and the physical properties were evaluated. The results are shown in Table 1.

Comparative Example 1 A laminate molded product was molded in exactly the same manner as in Example 1 except that no interleaf was used, and the physical properties were evaluated.

The results are shown in Table 1.

Comparative Example 2 A laminate was molded in exactly the same manner as in Example 2, except that no interleaf was used, and its physical properties were evaluated.

The results are shown in Table 1.

Comparative Example 3 Polyimide film (LARK-
TP I film, tensile elongation at break: 8.5%, thickness 12
Example 2 except that molding was performed at 350° C. and under a pressure of 200 Kg/cm
After obtaining a laminate molded product in exactly the same manner as above, the physical properties were evaluated. The results are shown in Table 1.

[Brief explanation of drawings]

FIG. 1 is a sectional view of the laminate molded product of the present invention. 1 indicates a fiber-reinforced polyimide resin layer, and 2 indicates a polyimide film (interleaf).

Claims (4)

[Claims] (1) The glass transition point of the matrix is 250°C to 350°C
The fiber reinforced polyimide resin layer has a tensile elongation at break of 90% or more and a glass transition point of 250°C to 350°C.
It has a laminated structure in which interleaves made of polyimide films having a temperature of 100 °C are laminated alternately, and the polyimide of the fiber-reinforced polyimide resin layer and the polyimide film of the interleaves are heat-sealed to each other. Interleaf-containing fiber-reinforced polyimide resin laminate molded product. (2) The laminated structure is manufactured by alternately laminating heat-sealable fiber-reinforced polyimide resin prepregs and heat-sealable polyimide films and heat-pressing them. The laminate molded article according to item 1. (3) The polyimide of the fiber-reinforced polyimide resin layer contains a tetracarboxylic acid component containing 80 mol% or more of a biphenyltetracarboxylic acid component and a diamine component containing 80 mol% or more of an aromatic diamine having a plurality of benzene rings. The laminate molded article according to claim 1, which is a polyimide resin derived from. (4) Interleaf's polyimide film has the following formula: ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ or ▲ Mathematical formulas, chemical formulas, tables, etc. The laminate molded product according to claim 1, which is made of a polyimide comprising repeating units of ▼.