JPH07258542A - Resin composition for composite material, intermediate for composite material, and composite material - Google Patents

Abstract

PURPOSE:To prevent the separation of microballoons from a cyanate ester resin at the curing step, etc., of a resin compsn. comprising the resin and the microballoons without detriment to the excellent heat resistance. moisture- absorbing properties, and electrical characteristics of the compsn. and thus obtain the resin compsn. which gives a homogeneous lightweight composite material when cured. CONSTITUTION:This compsn. contains a cyanate ester resin, microballoons, and a fiber. This intermediate is obtd. by molding the compsn. into a sheet or film. This composite material contains a cured item obtd. by curing the compsn. or the intermediate.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fiber-containing resin composition for a lightweight composite material. More specifically, the present invention relates to a lightweight composite material which is excellent in heat resistance, water resistance and electrical characteristics and which is homogeneous. The present invention relates to a resin composition for a lightweight composite material that can be obtained. The present invention also relates to an intermediate material for a composite material obtained by molding the resin composition for a composite material, and a composite material containing a cured product obtained by curing the resin composition for an composite material or the intermediate material.

[0002]

2. Description of the Related Art Composite materials having carbon fiber, glass fiber or the like as a reinforcing material are widely used for sports / leisure products such as golf shafts, fishing rods and tennis rackets, aircraft and general industrial materials.

In particular, a composite material comprising a fiber-reinforced surface layer and a lightweight core material has a high specific strength and a high specific rigidity.
There is a feature that a lightweight and highly rigid molded body can be obtained,
Attention has been paid.

Conventionally used bismaleimide /
The resin composition for a lightweight composite material including the micro hollow sphere system and the epoxy resin / micro hollow sphere system is good in heat resistance, but not satisfactory in hygroscopicity. Also, for example, the 36th International Sampe Symposium 19
April 1991, p. 336 (36th International SAMPE Symposiu
m, April P.336 (1991)), a resin composition for a lightweight composite material composed of a cyanate ester resin / micro hollow sphere system is excellent in heat resistance, hygroscopicity and electric characteristics, When manufacturing a thick composite material, there is a drawback that the light weight minute hollow spheres are separated from the resin because the resin viscosity is low at the time of heat curing.

Although a method of mixing an epoxy resin with the above resin composition has been proposed for the purpose of improving such drawbacks, it is not a preferable method in terms of electrical characteristics.

There is also a method of adding an inorganic compound type thixotropic agent such as montmorillonites and fine silica powder to the above resin composition in order to increase the viscosity, but the weight is increased and the electrical characteristics are deteriorated. There is a problem of doing.

[0007]

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems of the prior art, and has excellent heat resistance of a resin composition composed of a cyanate ester resin / micro hollow sphere system, A resin composition for a composite material capable of preventing separation of fine hollow spheres and a resin at the time of heat-curing or the like without deteriorating hygroscopicity and electric properties, thereby obtaining a homogeneous lightweight composite material after curing. It is intended to provide.

[0008]

Means for Solving the Problems As a result of intensive research aimed at achieving the above object, the present inventor has further added fibers to a composition containing a cyanate ester resin and micro hollow spheres as main components. It was found that the separation of the minute hollow spheres and the resin during heat curing and the like can be prevented, and a homogeneous lightweight composite material can be obtained, which led to the present invention.

That is, the present invention relates to a resin composition for a composite material, which comprises (A) a cyanate ester resin, (B) a micro hollow sphere and (C) a fiber. Further, the present invention relates to an intermediate material for a composite material, which is obtained by molding the above resin composition for a composite material into a sheet shape or a film shape, and the present invention also relates to the above-mentioned composite material. The present invention relates to a composite material comprising a cured product obtained by curing a resin composition or an intermediate material for a composite material as a constituent element.

The present invention will be described in detail below.

Examples of the cyanate ester resin (A) used in the present invention include cyanate ester resins derived from various phenol resins such as bisphenol A, bisphenol F, phenol novolac, cresol novolac, and phenol-dicyclopentadiene resin. Can be mentioned. More specifically, examples of the bisphenol type cyanate ester resin include, for example, B-10, B-30, M-10, M-30 and T-3 manufactured by Rhone Poulenc.
0, F-10, L-10 (all are trade names) and the like. Examples of the phenol novolac type cyanate ester resin include PT resin manufactured by Allied Signal. Further, examples of the phenol-dicyclopentadiene type cyanate ester resin include XU71787 (trade name) manufactured by Dow Chemical Company.

Further, in order to improve the toughness of the cyanate ester resin, various kinds of plastics or rubbers are usually added to 100 parts by weight of the cyanate ester resin.
-30 parts by weight, preferably 5-15 parts by weight can be added.

Examples of the above plastics include polycarbonate, polyether sulfone, phenoxy resin,
There are polyetherimide, polyvinyl formal, polyvinyl butyral, polyethylene terephthalate and the like.
Examples of the rubbers include butadiene-acrylonitrile rubber, styrene-butadiene rubber, acrylonitrile-butadiene-styrene resin, and silicone resin.

Further, in order to further improve the toughness of the cyanate ester resin, ultrafine particles of a polymer can be added to the resin. Examples of the ultrafine particles of the polymer include styrene resin, divinylbenzene resin, styrene-divinylbenzene resin, benzoguanamine resin,
Super composed of melamine resin, benzoguanamine-melamine co-condensation resin, urea resin, silicone resin, ethylene-acrylic acid copolymer resin, methyl methacrylate resin, n-butyl acrylate resin, acrylic-urethane resin, polyamide resin, aromatic polyester resin, etc. There are fine particles.

Examples of the fine hollow spheres (B) used in the present invention include inorganic materials such as glass, alumina silicate, ceramics and carbon, as well as phenol resin, vinylidene chloride-acrylonitrile copolymer, epoxy resin, urea resin, Examples include organic materials such as melamine resins. Of these, glass micro hollow spheres are particularly preferable in terms of strength and weight reduction. The size of the hollow microspheres is not particularly limited, but is usually 1
It has a particle size distribution of 0 to 200 μm, preferably 80 to 120 μm. Furthermore, 80-120 μm and 20-
It is particularly preferable to blend and use those having a particle size distribution of 50 μm because the strength of the obtained molded body can be further improved.

When glass micro hollow spheres are used,
It is effective to use a silane coupling agent or the like in order to increase the interfacial adhesion strength with the matrix resin and further improve the physical properties of the obtained molded product. Examples of such silane coupling agents include β- (3,4-epoxycyclohexyl) -ethyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-chloropropyltrimethoxysilane and the like. In addition, it is also possible to use a titanium coupling agent and a zirconium coupling agent.

The fine hollow spheres (B) according to the present invention are usually 5 to 6 with respect to 100 parts by weight of the cyanate ester resin.
5 parts by weight, preferably 7 to 25 parts by weight are added. When the addition amount of the above-mentioned micro hollow spheres is less than 5 parts by weight, the effect of weight reduction is small, and when it exceeds 65 parts by weight, mixing with a resin becomes difficult, and moldability tends to cause a problem. Is also not preferable.

The (C) fibers used in the present invention include:
For example, polyethylene fibers (eg polyethylene pulp), polypropylene fibers, vinylon fibers, nylon fibers, polyester fibers, polyacrylic fibers, aramid fibers and other organic fibers, asbestos fibers, glass fibers, silicon carbide fibers, carbon fibers and other inorganic fibers Is mentioned. Among them, polyethylene fibers, particularly polyethylene pulp, are preferable because they are lightweight, have good thixotropic properties, and have excellent electrical properties such as a low dielectric constant. When carbon fiber is used, the insulating property of the obtained molded article decreases,
The composition of the present invention is not suitable when it is used in applications where insulation properties such as wiring substrates are required, and it is preferably used when it is used as a heat resistant material.

The shape of the (C) fiber according to the present invention is not particularly limited, but for example, a strand in which several hundreds to tens of thousands of filaments are usually bundled is usually 0.5 to 100 mm.
Chopped strands (short fibers) cut to length
However, it is preferable because it is easily dispersed uniformly. Further, from the viewpoints of dispersibility, lightness and electrical characteristics, as the (C) fiber according to the present invention, ultrafine fibers and hollow fibers are preferable.

The (C) fiber according to the present invention is usually added in an amount of 1 to 20 parts by weight, preferably 2 to 10 parts by weight, based on 100 parts by weight of the cyanate ester resin. When the amount of the above fiber added is less than 1 part by weight, the effect of the addition is small,
There is a tendency that the fine hollow spheres and the resin are separated from each other when the resin composition is mixed, or the resin composition is damaged by a slight impact at a low temperature. When the amount of the above-mentioned fibers added exceeds 20 parts by weight, the fibers are entangled with each other during the mixing of the resin composition, and the fibers tend to be offset, so that a homogeneous composition tends not to be obtained.

In the resin composition of the present invention, a curing agent for the above cyanate ester resin is usually added and used, and examples of such a curing agent include Co ⁺² , Co ⁺³ ,
Zn ⁺² , Cu ⁺² , Mn ⁺² , Mn ⁺³ , Al ⁺³ , Fe ⁺³ , P
Examples thereof include acetylacetone complexes of metal elements such as b ⁺² and Ni ⁺² .

The above curing agent is cyanate ester resin 1
50 parts by weight to 500 parts by weight as a normal metal
m, preferably 200 to 300 ppm. If the amount of the above-mentioned curing agent added is less than the above range, sufficient curing will not occur, and if it exceeds the above range, the calorific value will be too large and the moldability will tend to be problematic.

Further, in the resin composition of the present invention, a curing accelerator for the above cyanate ester resin may be added and used. Examples of the curing accelerator include phenols and amines. it can. Furthermore, in the resin composition of the present invention, a reaction diluent, a colorant and the like may be mixed as other additives.

The method for producing the resin composition for a composite material of the present invention is not particularly limited, but a particularly preferable method for producing a uniform composition will be described below.

When mixing (A) cyanate ester resin, (B) micro hollow spheres and (C) fiber, and optionally a curing catalyst, the cyanate ester resin is first heated and melted at 70 to 120 ° C. to obtain a viscosity. Is sufficiently lowered before adding the hollow microspheres and fibers. Then, after mixing them uniformly, the curing catalyst is quickly added.
Then, the obtained compound (resin composition) is extracted from the mixer and rapidly cooled.

In the above-mentioned manufacturing process, the micro hollow spheres are easily broken when excessive shearing force is applied. Therefore, in order to avoid this, the viscosity of the cyanate ester resin should be adjusted during mixing, and the shearing force of mixing should be limited. Is desirable. For example, the viscosity of the cyanate ester resin at the time of mixing is preferably adjusted to about 500 to 25,000 cP, particularly preferably 800 to 13,000 cP. If the viscosity of the cyanate ester resin during mixing is lower than 500 cP, it tends to be sticky or flow when molded into a sheet or the like, which is not preferable. Further, if the viscosity of the cyanate ester resin during mixing is higher than 25,000 cP, it is difficult to uniformly mix and the fine hollow spheres tend to be damaged during mixing, which is not preferable.

In the above manufacturing process, it is preferable to use a mixer having a small shearing force. Examples of such a mixer include a planetary mixer, a twin-screw kneader, a static mixer and the like. Particularly, the planetary mixer and the kneader preferably have a transmission.
In addition, when the shearing force at the time of mixing is insufficient, the mixing is not sufficient, the minute hollow spheres, the fibers and the curing catalyst are not uniformly dispersed, and a molded product having sufficient physical properties cannot be obtained.

The resin composition for a composite material of the present invention obtained as described above can be used as a filling material for various composite materials, and the resin composition is cured by combining it with a fiber reinforcement or the like. By doing so, the composite material of the present invention is obtained. As a specific method thereof, for example, a glass fiber reinforced resin (FRP) or carbon fiber reinforced resin (CFRP) pipe or hollow complex shape product is obtained by heating the above resin composition as it is with an extruder or an injecting machine. And the like, followed by heating and curing. The conditions for heating and curing the resin composition are usually 90 to 220 ° C., preferably 120 to 1
At 80 ° C, usually 10 minutes to 10 hours, preferably 30 minutes to
It takes about 3 hours.

The resin composition for a composite material of the present invention can be used as an intermediate material for a composite material by molding it into a sheet or a film, for example, and the intermediate material of the present invention can be used as a reinforcing fiber. The composite material of the present invention can also be obtained by curing in combination with the above.

There are various methods for molding the above resin composition into a sheet or film, and typical examples include a method using a calendar coater, a reverse roll coater, a knife over roll coater and the like. . The coating thickness of the above resin composition (thickness of the intermediate material of the present invention) is usually 0.5 to 5 mm, preferably about 0.2 to 2 mm. Release paper is generally used as a material to be coated used in the above-mentioned molding, but a film such as plastic can also be used.

As a method of combining the intermediate material for composite material of the present invention with the reinforcing fiber, there is a method of laminating and molding the intermediate material with the reinforcing fiber to obtain a molded body. Also,
The conditions for curing the intermediate material are usually 90 to 220.
C. is 10 minutes to 10 hours, preferably 120 to 180.degree. C. and 30 minutes to 3 hours.

The reinforcing fiber used in the composite material of the present invention is not particularly limited, and all fibers used as the reinforcing fiber of the composite material can be used. For example, glass fiber, quartz fiber, carbon fiber, aramid fiber, polyethylene fiber, silicon carbide fiber and the like can be mentioned. Further, it is also possible to use fibers having a hybrid structure of two or more kinds selected from these.

The form of the reinforcing fiber is not particularly limited as long as it can be wound or laminated, and examples thereof include a strand, a unidirectional prepreg, a woven prepreg, and a braid.

[0034]

The present invention will be described in more detail with reference to the following examples, but the present invention is not limited thereto. Example 1 Dicyclopentadiene-phenolic cyanate ester resin (manufactured by Dow Chemical Co., trade name: XU71787)
1 kg and 0.02 kg of polyethylene pulp having a fiber diameter of 1 to 20 μmφ and a fiber length of about 1 mm were fed into a planetary mixer and uniformly mixed at 110 ° C., and then glass micro hollow spheres (Sumitomo 3M, trade name: 0.15 Kg of scotch light glass bubbles A16 / 500) was added and uniformly mixed. Further, fine powdery cobalt acetylacetone was added to the obtained mixture as a curing catalyst.
After quickly adding 0017 Kg and stirring for 5 minutes, the resin composition obtained from the above mixer was extracted and cooled.

This resin composition was remelted at 70 ° C. and a calender roll coater was used to obtain a sheet-shaped intermediate material for a composite material having a thickness of 1.5 mm. -1 for the obtained intermediate material
It was stored in a freezer at 8 ° C. Example 2 When the sheet-shaped intermediate material for a composite material produced in Example 1 and frozen and stored was taken out from the freezer at −18 ° C. and thawed, no damage was found in the intermediate material.

Next, 301 × 301 mm square, thickness 10 m
First, four 300 × 300 mm square glass fiber cloth prepregs were laminated on a stainless steel mold of m, and the sheet-shaped intermediate material obtained in Example 1 was placed on the laminated 300 × 300 m.
Stick 6 pieces cut in m-square and 300 on it
Four glass fiber cloth prepregs of 300 mm square were laminated. A mold release film was applied to the upper and lower surfaces of the obtained laminate, and a stainless steel contact plate was placed on the outer side of the release film. The temperature was raised from room temperature to 150 ° C. at a heating rate of, and maintained at 150 ° C. for 1 hour. After that, heat to 180 ° C and continue at 180 ° C for 3
After being held for a period of time to cure the laminate, it was slowly cooled to room temperature. The obtained molded plate (composite material) was extremely lightweight and finished well despite its thickness. Also,
When the molded plate was cut with a cutting machine and the cross section was observed with a microscope, the cut surface was homogeneous without separation of the cyanate ester resin and the micro hollow spheres.

As the above glass fiber cloth prepreg, 1 of cyanate ester resin (XU71787) containing 250 ppm of cobalt acetylacetone was used.
A glass fiber cloth was impregnated with a 0% methyl ethyl ketone solution, and the solvent was removed by heating with warm air. Comparative Example 1 A resin composition for a composite material obtained in the same manner as in Example 1 except that polyethylene pulp was not used was molded into a sheet-shaped intermediate material for a composite material in the same manner as in Example 1 and then at −18 ° C.
Stored in the freezer. Then, when it was taken out from the freezer and thawed to produce the following molded product, a part of the intermediate material was damaged.

Next, a plate-shaped molded body (composite material) was obtained in the same manner as in Example 2 using the above-mentioned intermediate material, and the innermost layer sheet was formed on a part of the surface of the obtained molded body. A slight deformation was observed, which is considered to be due to the breakage of the resin composition for composite materials. Further, when the molded body was cut with a cutting machine and the cross section was observed with a microscope, the glass micro hollow spheres and the cyanate ester resin were separated in the layer, and the adhesion between the upper glass fiber cloth and the interlayer was insufficient. It was

[0039]

The resin composition for a composite material of the present invention contains fibers, and the cyanate ester resin and the lightweight hollow microspheres do not separate from each other during heating and curing. Therefore, by using the resin composition for a composite material of the present invention, a homogeneous composite material and a homogeneous intermediate material for a composite material can be obtained. Further, the intermediate material of the present invention obtained by molding the resin composition for a composite material of the present invention into a sheet shape or the like has a certain degree of strength at low temperature storage, and therefore is not easily damaged or damaged during transportation or work. It does not collapse.

For the above reason, by using the resin composition for a composite material of the present invention, it becomes possible to obtain a composite material having excellent heat resistance, water resistance and electric characteristics and having a good finish. Improves reliability.

Claims (3)

[Claims] 1. A cyanate ester resin (A), (B)
A resin composition for a composite material, which comprises fine hollow spheres and (C) fibers. 2. An intermediate material for a composite material, which is formed by molding the resin composition for a composite material according to claim 1 into a sheet shape or a film shape. 3. A composite material comprising a resin composition for a composite material according to claim 1 or a cured product obtained by curing the intermediate material for a composite material according to claim 2.