JP2594964B2 - Polyimide composite material - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a composite material having excellent heat resistance, chemical resistance, mechanical strength, and excellent moldability.

[Conventional technology]

2. Description of the Related Art Conventionally, composite materials using a polyimide matrix as a matrix have been attracting attention as structural materials for spacecraft and the like because of their excellent mechanical strength, particularly excellent strength retention at high temperatures, and excellent solvent resistance and dimensional stability.

However, even if the above physical properties are excellent, polyimide as a matrix generally has a high melt viscosity, so molding and processing conditions are stricter than those of a composite material having a matrix of an engine nearing plastic such as polycarbonate or polyethylene terephthalate. Was. In addition, special polyimides with low melt viscosity and excellent workability have low heat distortion temperature and are soluble in solvents such as halogenated hydrocarbons. There was a problem with chemical properties.

Accordingly, the present inventors have previously disclosed in Japanese Patent Application No. 61-090170 a technique for solving such a problem. (Wherein R represents an aliphatic group having 2 or more carbon atoms, a cycloaliphatic group, a monocyclic aromatic group, a condensed polycyclic aromatic group, or a non-cyclic group in which aromatic groups are directly or mutually linked by a bridge member. Represents a tetravalent group selected from the group consisting of condensed polycyclic aromatic groups.) A composite material comprising a polyimide having a repeating unit represented by the following formula and a fibrous reinforcing material was proposed.

This composite material has much higher heat resistance and other mechanical properties compared to a matrix material of ordinary engine nearing plastics represented by polyethylene terephthalate, polybutylene terephthalate, polyether sulfone, polysulfone, polyphenylene sulfide, etc. , But the processability is still inferior to composites matrixing these polymers.

[Problems to be solved by the present invention]

An object of the present invention is to provide a composite material having significantly improved moldability without impairing properties inherent to polyimide, mechanical strength, chemical resistance, dimensional stability, and strength retention at high temperatures. .

[Means for solving the problem]

The present inventors have conducted intensive studies to solve the above problems, and as a result, have found that a resin composition comprising a novel polyimide and a specific amount of aromatic polysulfone is effective for the purpose, and completed the present invention. Was.

That is, the present invention uses the formula (Where R is Represents a tetravalent group selected from the group consisting of ) 99.9 to 50% by weight of a polyimide composed of a repeating unit represented by: And a polyimide-based composite material comprising a fibrous reinforcing material and a resin composition comprising from 0.1 to 50% by weight of an aromatic polysulfone comprising at least one repeating unit selected from the group consisting of: 5-85 by content
% Of a fibrous reinforcing material.

The production of the polyimide used in the present invention is described in Japanese Patent Application No.
205283, 61-046369, 61-274206.

That is, the expression The polyamic acid obtained by reacting 4,4'-bis (3-aminophenoxy) biphenyl represented by the following formula with one or more tetracarboxylic dianhydrides in an organic solvent is imidized.

As the tetracarboxylic dianhydride used at this time, ethylene tetracarboxylic dianhydride, butanetetracarboxylic dianhydride, cyclopentanetetracarboxylic dianhydride, pyromellitic dianhydride, 3,3 ', 4,4'-benzophenonetetracarboxylic dianhydride, 2,2 ', 3,3'
-Benzophenonetetracarboxylic dianhydride, 3,3 ', 4,
4'-biphenyltetracarboxylic dianhydride, 2,2 ', 3,
3'-biphenyltetracarboxylic dianhydride, 2,2-bis (3,4-dicarboxyphenyl) propane dianhydride, 2,2
-Bis (2,3-dicarboxyphenyl) propane dianhydride, bis (3,4-dicarboxyphenyl) ether dianhydride, bis (3,4-dicarboxyphenyl) sulfone dianhydride, 1,1- Bis (2,3-dicarboxyphenyl) methane dianhydride, bis (2,3-dicarboxyphenyl) methane dianhydride, bis (3,4-dicarboxyphenyl) methane dianhydride, 4- [4- (3,4-dicarboxyphenoxy) phenoxy] phthalic dianhydride, 2,3,6,7-naphthalenetetracarboxylic dianhydride, 1,4,5,8-naphthalenetetracarboxylic dianhydride 1, 2,5,6-naphthalenetetracarboxylic dianhydride, 1,2,3,4-benzenetetracarboxylic dianhydride, 3,4,9,10-perylenetetracarboxylic dianhydride, 2,3, 6,7-anthracenecarboxylic dianhydride,
1,2,7,8-phenanthrene tetracarboxylic dianhydride and the like, and these tetracarboxylic dianhydrides are used alone or in combination of two or more.

The aromatic polysulfone used as a fluidization accelerator in the present invention is Polysulfone having a repeating unit such as, particularly a typical aromatic polysulfone has a general formula "VIC TREX PE"
Polyethersulfone commercially available under the trademark "S" and / or a general formula "UDEL POLYS"
Polysulfone commercially available under the trademark ULFONE ".

These aromatic polysulfones can be freely produced in various degrees of polymerization, and those having a melt viscosity characteristic suitable for a target blend can be arbitrarily selected.

The resin composition used in the present invention is the polyimide 99.9 ~
It is adjusted so that 50% by weight and aromatic polysulfone are in the range of 0.1 to 50% by weight.

The polyimide / aromatic polysulfone resin composition according to the present invention exhibits a remarkably low melting point viscosity in a high sound range of 350 ° C. or higher. A good fluidizing effect of the aromatic polysulfone is recognized even in a small amount, and the lower limit of the composition ratio is 0.1% by weight, preferably 0.5% by weight or more.

The mechanical strength of aromatic polysulfone at high temperatures belongs to the excellent class among heat-resistant resins, but the mechanical strength, particularly the Izod impact strength, is inferior to that of polyimide. If the amount is too large, the original mechanical strength of the polyimide cannot be maintained, and therefore the mechanical strength of the composite material cannot be maintained, which is not preferable. Therefore, there is an upper limit to the composition ratio of the aromatic polysulfone, which is 50% by weight or less, preferably 30% by weight or less.

The fibrous reinforcing material used in the present invention means, for example, unidirectional long fibers such as glass fiber yarns, rovings, and carbon fiber tows, and multidirectional continuous fibers such as woven fabrics, mats, and felts.

These fibrous reinforcing materials are E-glass, S-glass, T-glass.
Glass fiber such as glass, C-glass, AR-glass, PAN
System, pitch-based, rayon-based carbon fiber, aromatic polyamide fiber such as Kevlar of DuPont, silicon carbide fiber such as Nicalon of Nippon Carbon Co., metal fiber such as stainless steel fiber, other alumina fiber, boron fiber, etc. These fibers may be used alone or in combination.
Further, if necessary, it can be used in combination with other reinforcing materials such as potassium titanate fiber, mica, and calcium silicate. In this case, the composite material of the present invention can be obtained by previously mixing the resin composition and the reinforcing material and impregnating the mixture with the fibrous reinforcing material.

In selecting these fibrous reinforcing materials, they should be selected based on mechanical properties such as strength, elastic modulus, elongation at break, electrical properties, specific gravity, etc. of the fibers in accordance with the properties required for the composite material. For example, carbon fibers, glass fibers, and the like should be selected when required values for specific strength and specific elastic modulus are high, and carbon fibers, metal fibers, and the like are preferable when electromagnetic wave shielding characteristics are required. Alternatively, when electrical insulation properties are required, glass fiber or the like is suitable.

The fiber diameter and the number of convergent fibers of the fibrous reinforcing material differ depending on the type of the fibrous reinforcing material used. For example, in the case of carbon fiber, the fiber diameter is generally 4 to 8 μm, and the number of convergent fibers is generally 1000 to 12000. The smaller the fiber diameter is, the better the mechanical properties of the obtained composite material are.

The surface treatment of the fibrous reinforcing material is preferable from the viewpoint of improving the adhesion to the matrix resin. For example, in the case of glass fiber, it is particularly preferable to treat the fibrous reinforcing material with a silane-based or titanate-based coupling agent.

The volume content of these fibrous reinforcing materials in the composite material is 5
~ 85%, preferably 30-70%. The effect of the reinforcing material, that is, the volume content of the fibrous reinforcing material is low, cannot be expected. Conversely, if the reinforcing material is high, the interlayer strength of the obtained composite material is significantly reduced, which is not preferable.

The fibrous reinforcing material is impregnated with the above-described resin composition to obtain a fiber-reinforced composite material. In this case, all ordinary methods can be used. For example, the above-mentioned resin composition is impregnated in a molten state by impregnating a fibrous reinforcing material in a molten state, or in a state in which a powdery resin composition is suspended in a gas such as air or suspended in a liquid such as water. Fluid bed method and the like can be mentioned.

In the case of the melt impregnation method, it is preferable to produce a composite material comprising a fibrous reinforcing material and a resin composition as follows.

That is, a unidirectional long fiber drawn from a plurality of bobbins, for example, a fiber sheet in which tows are aligned or a multidirectional continuous fiber is applied with a constant tension in a pulling direction by a tension adjusting roll.
On the other hand, the resin composition is heated and melted by an extruder, and is applied from a die to the surface of a heating roll heated to a predetermined temperature. The coating thickness should be determined by the set percentage of resin content in the resulting composite. Then, the above-mentioned fiber sheet or multidirectional continuous fiber is brought into contact with the surface of the heating roll with a constant tension to impregnate the heating roll. In this case, the temperature, the number, and the like of the heating rolls should be determined according to the resin composition, the take-up speed, and the like.

On the other hand, in the case of the fluidized bed method, it is particularly effective to heat and melt the resin composition in the fibrous reinforcing material after drying as necessary after impregnation in order to obtain an integrated fiber-reinforced composite material. The particle size at the time of impregnation is desirably small, and is preferably not more than the diameter of the fiber filament to be used.

The composite materials obtained as described above are laminated, and a molded product having a desired shape can be manufactured by heat compression.

The heating temperature at the time of lamination molding may be 300 ° C. or higher, but is preferably 350 to 450 ° C. The pressing force varies depending on the shape, but usually 10 kg / cm ² or more is sufficient.

〔Example〕

Hereinafter, the present invention will be described in more detail with reference to Synthesis Examples, Examples and Comparative Examples.

Synthesis Example-1 A reaction vessel equipped with a stirrer, a reflux condenser, and a nitrogen inlet tube was charged with 4.68 kg (10 mol) of 4,4'-bis (3-aminophenoxy) biphenyl and 52.15 kg of N, N-dimethylacetamide. , And 2.11 kg (9.7 mol) of pyromellitic dianhydride were added in portions at room temperature under a nitrogen atmosphere while paying attention to the rise in solution temperature, and the mixture was stirred at room temperature for about 20 hours. The logarithmic viscosity of the polyamic acid thus obtained is 0.52dl
/ g. Here, the logarithmic viscosity is a value measured at 35 ° C. in an N, N-dimethylacetamide solvent, a concentration of 0.5 g / 100 ml solvent.

4.04 at room temperature under nitrogen atmosphere
kg (40 mol) of triethylamine and 6.12 kg (60 mol) of acetic anhydride were added dropwise. Stir at room temperature for 20 hours,
A yellow slurry was obtained. This slurry was separated by filtration to obtain a pale yellow polyimide powder. This polyimide powder was sludged with methanol, separated and dried under reduced pressure at 180 ° C. for 8 hours.
2 kg (97.9% yield) of polyimide powder was obtained.

Examples-1 to 4 Polyimide powder obtained in Synthesis Example-1 and aromatic polysulfone powder, which are commercially available VICTREX PES
After dry blending 3600P (trademark of ICI) with various compositions as shown in Table 1, a 40 mm diameter extruder equipped with a screw having a compression ratio of 3.0 / 1.0 (processing temperature of 360 to 390)
C.) to perform extrusion while melt-kneading to obtain a uniformly blended pellet.

Next, a composite material was obtained using the pellets and the unidirectional long fibers. That is, a carbon fiber tow (Vesfight HTA-7-3000) 100 drawn from 100 bobbins was prepared to form a fiber sheet having a width of 150 mm. The resin pellet was heated and melted at 390 ° C. in an extruder. The fiber sheet was applied from a die to a 240 mm diameter first heating roll heated to 390 ° C. with a thickness of 70 μm, and the fiber sheet was brought into contact with the surface of the first heating roll with a tension of 150 kg. The fiber sheet moves at a speed of 50 cm / min, contacts the second heating roll maintained at the same temperature as the first heating roll, and further contacts the third heating roll at the same temperature as the first heating roll to maintain the same. The resin was impregnated, gradually cooled in a slow cooling furnace maintained at 200 ° C., and wound up by a take-up machine. The obtained composite material had a width of 150 mm and a thickness of 0.13 mm.

Laminate 20 composite materials in the same direction, 390 ℃, 20kg /
After hot pressing under a condition of cm ² for 20 minutes to obtain a flat plate of 200 × 200 mm, the internal void ratio, the fiber content volume percentage, the bending strength, and the bending elastic modulus were measured. Here, the internal void ratio is determined from the specific gravity of the flat plate and the fiber content weight percentage.

The results are shown in Table 1. As can be seen from Table 1, the internal void ratio is almost 0, and has high mechanical strength.

[Comparative Examples 1 and 2] Measurement of internal void ratio, fiber content percentage, flexural strength and flexural modulus of a flat plate obtained by the same operation as in Examples 1 to 4 using the resin compositions shown in Table 1. The results are shown in Table 1 as Comparative Examples 1 and 2. Comparative Example 1 has a high internal void ratio, and Comparative Example 2 does not have sufficient mechanical strength.

[Examples 5 to 8] Table 2 using pellets having the same resin composition as in Example-2.
A composite material was obtained using the fibrous reinforcing material shown in FIG. The impregnation conditions were the same as in Examples 1 to 4, except that the thickness of the resin coating on the surface of the first heating roll was changed as shown in Table-2. Then, the obtained composite materials were laminated in the same direction by the number of sheets shown in Table 2, then formed into a flat plate in the same manner as in Examples 1 to 4, and evaluated for physical properties. Table 2 shows the results.

[Examples 9 to 10] A composite material was obtained by the following method using a multidirectional continuous fiber (plain woven fabric) shown in Table 2 as a fibrous reinforcing material for pellets having the same resin composition as in Example-2. . The multidirectional continuous fiber placed on the pay-out shaft is pulled in the take-off direction by a tension adjusting roll for 30 minutes.
After applying a tension of kg, the mixture was passed through three heating rolls having a diameter of 240 mm while being in contact with each other. On the other hand, resin pellets are extruded
Heated and melted to 390 ° C, the first heated to 390 ° C from the die
The fiber was applied to the roll at the thickness shown in Table 2, and the fiber was brought into contact with the surface of the first heating roll to start impregnation. Fibre is 50
After moving at a speed of cm / min, the second heating roll and the third heating roll heated to the same temperature as the first heating roll were successively contacted, gradually cooled in a slow cooling furnace maintained at 200 ° C., and then taken off by a take-off machine. Wound up. The obtained composite material was hot-pressed in the same manner as in Examples 1 to 4 except that the number of sheets shown in Table 2 was laminated to obtain a flat plate.
Physical properties were evaluated. Table 2 shows the results.

Synthesis Example-2 2.11 kg of pyromellitic dianhydride in Synthesis Example-1
Except that the amount was changed to 2.125 kg (9.75 mol), the same procedure as in Synthesis Example 1 was performed to obtain a polyamic acid having an logarithmic viscosity of 0.72 dl / g. From this polyamic acid solution, 5.4 k
g of pale yellow polyimide powder was obtained.

[Examples 11 to 13, Comparative Examples 3 and 4] Polyimide powder obtained in Synthesis Example-2 and aromatic polysulfone, commercially available UDEL POLYSULFONE P-
Extruding 1700 (trademark of Union Carbide, USA) with the composition shown in Table 3 using a 40 mm extruder (processing temperature 360-390 ° C) equipped with a screw having a compression ratio of 3.0 / 1.0 while melting and kneading, A blended pellet was obtained. Next, a composite material was obtained in the same manner as in Example 1 except that the impregnation temperature was changed to 380 ° C., and hot pressed at a molding temperature of 380 ° C. and a pressure of 20 kg / cm ² for 20 minutes to obtain a 200 × 200 mm flat plate. The bending strength and the bending elastic modulus of the obtained flat plate were measured.

The results are shown in Table 3 as Examples 11 to 13 and Comparative Examples 3 and 4.

Synthesis Example-3 2.11 kg of pyromethic dianhydride in Synthesis Example-1 was added to 3,
3.16 kg (9.85 mol) of 3 ', 4,4',-benzophenonetetracarboxylic dianhydride was added to N, N-dimethylacetamide 5
A polyamic acid having a logarithmic viscosity of 0.53 dl / g was obtained in the same manner as in Synthesis Example 1 except that 2.15 kg was changed to 62.1 kg. Further, 6.32 kg of a pale yellow polyimide powder was obtained by the same dehydration cyclization reaction as in Synthesis Example-1.

[Examples 14 to 17 and Comparative Examples 5 to 6] Using the polyimide powder obtained in Synthesis Example-3 and the aromatic polysulfone VICTREX PES 3600P, in the same manner as in Examples 1 to 4, the treatment temperature was changed to 320. The temperature was changed to 360360 ° C. to obtain a uniform blended pellet.

Then, after obtaining a composite material in the same manner as in Examples 1 to 4 except that the impregnation temperature was changed to 370 ° C, the molding temperature was 370 ° C and the pressure was 20 kg / cm.
The plate was hot-pressed under the conditions of ² for 20 minutes to obtain a 200 × 200 mm flat plate.
The bending strength and the bending elastic modulus of the obtained flat plate were measured. The results are shown in Table-4.

〔The invention's effect〕

According to the method of the present invention, a novel composite material having good moldability and processability is provided in addition to the excellent properties inherent to polyimide.

Claims (1)

(57) [Claims] (1) Expression (Where R is Represents a tetravalent group selected from the group consisting of ) 99.9 to 50% by weight of a polyimide composed of a repeating unit represented by: And a polyimide-based composite material comprising a fibrous reinforcing material and a resin composition comprising from 0.1 to 50% by weight of an aromatic polysulfone comprising at least one repeating unit selected from the group consisting of: 5-85 by content
% Of a fibrous reinforcing material.