JPH04178439A - Epoxy resin composition for light-weight composite material, intermediate and composite material - Google Patents

Abstract

PURPOSE:To obtain a high-strength and lightweight composition for lightweight composite materials suitable for inner core materials, etc., being readily laminated, co-crosslinkable with other prepreg by blending an epoxy resin with specific amounts of fine hollow spheres, a blowing agent and a curing agent. CONSTITUTION:(A) 50-95 pts.wt. epoxy resin is blended with (B) 5-35 pts.wt. fine hollow spheres (e.g. glass or alumina silicate), (C) 0.1-15 pts.wt. blowing agent (e.g. azobisisobutyronitrile), (D) 0.5-10 pts.wt. curing agent (e.g. dicyan) and (E) 0.5-10 pts.wt. curing promoter (e.g. 3-phenyl-1,1-dimethylurea). The composition is molded into a sheetlike or filmy state to give a single material intermediate for composite material, which is used to give lightweight composite materials or foamed and cured to give lightweight composite materials. Or a reinforced intermediate is obtained from the intermediate and the reinforcing material and processed to give lightweight composite materials or foamed and cured to give lightweight composite materials.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to an epoxy resin composition for lightweight composite materials containing micro hollow spheres, a foaming agent, and a curing agent, an intermediate material formed by molding the same into a sheet shape, and an intermediate material. It relates to composite materials obtained by molding materials.

[Prior Art] In recent years, many high-rise buildings have been constructed, and it is desired to use lightweight materials for the interior parts of the high-rise buildings.

Furthermore, since the use of aircraft is increasing year by year, it is desired to reduce the weight of aircraft in order to improve transportation efficiency.

Especially when energy prices are rising as they have been recently,
The effect is significant because weight reduction can significantly reduce fuel costs.

On the other hand, the number of participants in tennis, golf, skiing, etc. has increased significantly, the types of sports have become more diverse, and equipment has become more sophisticated and lightweight. Weight reduction is becoming especially important as the number of women and elderly people increases.

Phenolic resin,
There are methods such as foaming rigid polyurethane foam, various vinyl foams, etc. during the reaction, or using a foaming agent. Also,
Microscopic hollow spheres dispersed in resin have also been used for various purposes. However, those using foaming did not have sufficient strength, and those using microscopic hollow spheres were insufficient for reducing weight.

[Problems to be Solved by the Invention] In view of this situation, the present invention provides interior materials for high-rise buildings, interior materials for aircraft, sports equipment materials, etc.
The purpose of the present invention is to conduct studies to reduce weight while maintaining strength, and particularly to provide a resin composition for lightweight materials such as internal core materials, and sheet-like intermediate materials and composite materials using the same.

[Means for Solving the Problems] As a result of intensive studies in accordance with the above objectives, the present inventors found that by adding micro hollow spheres, a foaming agent, and a curing agent to an epoxy resin, it is possible to create shapes from flat plates to complex shapes. It can be easily laminated to other prepregs, and can be co-crosslinked (cm-cur) with other prepregs.
We have discovered that e) is possible and that a high-strength, lightweight composition can be obtained, and we have also developed a method for forming an intermediate material in the form of a sheet or film, and a composite material obtained by molding the intermediate material. Heading, we arrived at the present invention.

That is, the present invention provides a resin composition for lightweight composite materials comprising (A) an epoxy resin, (B) micro hollow spheres, (C) a foaming agent, (D) a curing agent, and (E) a curing accelerator. be.

The present invention also provides an intermediate material for a composite material in which the resin composition is formed into a sheet, and a composite material obtained by molding the intermediate material.

The present invention will be explained in more detail below.

The epoxy resin (A) used in the present invention includes liquid epoxy resin and/or solid epoxy resin,
Bisphenol A type epoxy resin, bisphenol F type epoxy resin, phenol novolac type epoxy resin,
Use various epoxy resins such as Talesol novolac type epoxy resin, glycidylamine type epoxy resin, glycidyl ester type epoxy resin, alicyclic epoxy resin, tris (glycidyl ether phenyl) methane, carboxylated butadiene-acrylonitrile rubber modified epoxy resin. It is also possible to use a mixture of two or more of these epoxy resins.

Furthermore, various plastics, rubbers, etc. can be added to improve the toughness of the epoxy resin.

For example, plastics include polycarbonate, polyether sulfone, phenoxy resin, polyvinyl formal, polyvinyl butyral, polyethylene terephthalate, and the like. Rubbers include butadiene-acrylonitrile rubber, styrene-butadiene rubber, acrylonitrile-butadiene-styrene resin, silicone resin, and the like.

Further, in order to further improve toughness, ultrafine polymer particles can be added. Ultrafine polymer particles include styrene resin, divinylbenzene resin, styrene-divinylbenzene resin, benzoguanamine resin, melamine resin,
Benzoguanamine-melamine cocondensation resin, urea resin, silicone resin, ethylene-acrylic acid copolymer resin, methyl methacrylate resin, n-butyl acrylate resin,
There are acrylic-urethane resins, nylon resins, etc.

(A) The amount of epoxy resin used is 50 to 95 parts by weight per 100 parts by weight of the composition. If the amount used is less than 50 parts by weight, the viscosity of the resin composition will increase, causing a problem in mixability, and if it exceeds 95 parts by weight, weight reduction will be insufficient, which is not preferable.

(B) Microscopic hollow spheres used in the present invention include inorganic materials such as glass, alumina silicate, ceramic, and carbon, and organic materials such as phenol resin, vinylidene chloride-acrylonitrile copolymer, epoxy resin, urea resin, and melamine resin. Examples include: Among these, glass microscopic hollow spheres are particularly preferred in terms of strength and weight reduction. The size of the micro hollow spheres is not particularly limited, but the particle size range is 10 to 200 μm, preferably 80 to 12 μm.
0 μm is used. More preferably, the particle size range is 80~
It is a blend of 120 μm and 20 to 50 μm, which can improve the strength. For epoxy resin composition films with a thickness of 1 mm or less, glass microscopic hollow spheres with a particle size range of 5 to 50 μm are preferred. Furthermore, when using glass micro hollow spheres, it is effective to use a silane coupling agent in order to increase the interfacial adhesive strength with the matrix resin and improve physical properties. As a silane coupling agent, β-(3,4-
epoxycyclohexyl)-ethyltrimethoxysilane, γ-glyndoxypropyltrimethoxysilane, γ-
Examples include chloropropyltrimethoxysilane.

(B) The amount of micro hollow spheres used is 5 to 35 parts by weight per 100 parts by weight of the composition. If the amount used is less than 5 parts by weight, weight reduction will be insufficient, and if it exceeds 35 parts by weight, the mixability of the resin composition will be insufficient, which is not preferable.

The blowing agent (C) used in the present invention includes azobisisobutyronitrile (AIBN), azodicarbonamide (ADCA), and azobisformamide (ABFA).
, azo type such as diazoaminobenzene (DAB), N, N
- dinitrosopentamethylenetetramine (DPT), N
, N'-dimethyl-N,N'-dinitrosoterephthalamide, etc., benzenesulfonyl hydrazide (BSH), toluenesulfonyl hydrazide (TSH)
), p, p'-oxybis(benzenesulfonylhydrazide) (0BSH) and the like.

Furthermore, during curing, those that generate gas when heated, ie, organic solvents such as aliphatic hydrocarbons, alcohols, ketones, and halogens, and inorganic salts such as ammonium carbonate and ammonium bicarbonate can be used.

Among them, azodicarbonamide and toluenesulfonyl hydrazide are preferred in terms of miscibility.

(C) The blowing agent is 0.1 to 1 per 100 parts by weight of the composition.
5 parts by weight are added. If the amount added is less than 0.1 part by weight, the foaming effect will be small, and if it exceeds 15 parts by weight, the amount of foaming will be too large, causing a problem in moldability, which is not preferable.

Further, the decomposition temperature, amount of gas generated, foaming speed, etc. of the foaming agent can be adjusted by adding a foaming aid.

As foaming aids, foaming promoters such as zinc white, zinc nitrate, tribasic lead phosphate, metal soap, borax, oxalic acid, urea, etc., and foaming suppressors such as hydroquinone can also be used in combination.

Examples of the curing agent (D) used in the present invention include dicyandiamide. Other hardening agents include
o-1 lylbiguanide, 2,6-xylenylbiguanide, phenylbiguanide, p-chlorophenylbiguanide, etc. are also used.

(D) The curing agent is 0.5 to 1 per 100 parts by weight of the composition.
0 parts by weight are added. If the amount added is less than 0.5 parts by weight, a sufficient cured product cannot be obtained, and if it exceeds 10 parts by weight, the calorific value is too large and there is a problem in moldability, which is not preferable.

The curing accelerator (E) used in the present invention includes 3-phenyl-1,1-dimethylurea, 3-p-chlorophenyl-1,1-dimethylurea, 3-(3,4-dichlorophenyl)-1 , 1-dimethylurea and the like. Further, BF, monoethylamine, BCQ, monoethylamine, etc. can also be used.

(E) The curing accelerator is 0.5 parts per 100 parts by weight of the composition.
~10 parts by weight are added. If the amount added is less than 0.5 parts by weight, a sufficient cured product cannot be obtained, and if it exceeds 10 parts by weight, the calorific value is too large and there is a problem in moldability, which is not preferable.

In the present invention, other additives such as reactive diluents, various fillers, plasticizers, foam stabilizers, thickeners, colorants, etc. can also be mixed.

The lightweight composite resin composition according to the present invention is produced as follows.

That is, the important steps in the production of lightweight composite resin compositions are 1) the order of addition of the formulations and 2) the mixing method. When mixing the epoxy resin, micro hollow spheres, foaming agent, curing agent, and curing accelerator, first add 80% of the epoxy resin.
The mixture is heated and melted at 0 to 200°C, and the hollow micro spheres are added after the viscosity has decreased. Mix evenly and bring the mixture to 60~
After cooling to 80°C, the blowing agent, curing agent and curing accelerator, previously mixed with the liquid epoxy resin, are quickly added, and the formulation is then rapidly cooled.

Regarding the mixing method, in the case of solids such as micro hollow spheres that easily break if too much shearing force is applied, it is important to adjust the viscosity and shear rate during mixing.

The viscosity during mixing is about 500 to 25,000 cps (preferably 800 to 13,000 cps is used. If the viscosity is too low, it will become sticky or fluid when formed into a sheet. If the viscosity is too high,
This is not preferred because it is difficult to mix uniformly and the micro hollow spheres are destroyed.

Examples of mixers with low shearing force include planet tower mixers, twin-screw kneaders, and static mixers. The planetary mixer and kneader are preferably equipped with a transmission. In particular, if the shearing force is large when the viscosity is high, heat generation occurs and the reaction progresses, causing the viscosity of the resin to increase and foaming to occur. When the shearing force is small, mixing is insufficient and the micro hollow spheres, foaming agent, curing agent and curing accelerator become non-uniform and sufficient physical properties cannot be obtained.

The flame-retardant lightweight composite material resin composition obtained in this way is injected into, for example, a carbon fiber hollow pipe or a complex structure using a heated extruder, injection machine, etc., and then heated and cured. This allows it to be used as a lightweight composite material.

There are various methods for manufacturing sheets or films (single intermediate materials for composite materials) that are intermediate materials for resin compositions for lightweight composite materials, but typical ones include calendar coaters, reverse roll coaters, and knife-over-roll coaters. It is done using etc. The coating thickness is 0.1~
A value of about 5 is preferable. Release paper is generally used as the material to be coated, but films such as plastic films can also be used.

Furthermore, release paper and films such as polyethylene can be used as the covering material. Furthermore, the sheet or film as a single intermediate for composite materials can be reinforced with glass scrim cloth, glass mat, nonwoven fabric, etc. and used as a reinforcing intermediate.

The single intermediate material or reinforcing intermediate material for composite materials manufactured in this way can be heated as is and used as a foamed lightweight material, but it can also be used as a foamed lightweight material. It can be used as a lightweight composite material by integrally molding it with a prepreg using fibers, alumina fibers, etc. The prepreg used in this case is particularly preferred because it easily co-crosslinks with the epoxy resin.

The cured product is obtained by heating at a temperature of 100 to 200°C for 10 minutes to 10 hours, preferably 110 to 130°C for 30 minutes to 2 hours. Alternatively, a molded plate obtained by previously curing a prepreg of carbon fiber, glass fiber, etc. and the above-mentioned single intermediate material for composite material or reinforcing intermediate material can be attached and cured by heating.

To create a laminated structure using a composite material obtained by molding an intermediate material, a sandwich structure with a lightweight composite material resin sheet or film as the core material is used, but depending on the number of core material layers, a single layer or a multilayer structure is used. It can be divided into Furthermore, it can also be used as a sandwich/Ivry-Rad structure or an interlayer hybrid structure. Examples of the single-layer sandwich structure include carbon fiber prepreg/resin sheet for lightweight composite materials/carbon fiber prepreg, glass fiber prepreg/resin sheet for lightweight composite materials/glass fiber prepreg, and the like. For example, the multilayer sandwich structure includes carbon fiber prepreg/resin sheet for lightweight composite materials/carbon fiber prepreg/resin sheet for lightweight composite materials/carbon fiber prepreg, glass fiber prepreg/resin sheet for lightweight composite materials/glass fiber prepreg/lightweight Resin sheet for composite materials/
Examples include glass fiber prepreg. Sandwich hybrids include, for example, carbon fiber prepreg/resin sheet for lightweight composite materials/glass fiber prepreg, aramid fiber prepreg/resin sheet for lightweight composite materials/carbon fiber prepreg, carbon fiber prepreg/aramid prepreg/lightweight composite material There are resin sheets/carbon fiber prepreg, glass fiber prepreg, etc.

Interlayer hybrids include carbon fiber prepreg/resin sheet for lightweight composite materials/glass fiber prepreg/resin sheet for lightweight composite materials/carbon fiber prepreg.

The molded product may be flat, curved, tubular, or rod-shaped.

In the case of tubular and rod-shaped molded products, the skin layer is made of prepreg of carbon fiber, aramid fiber, glass fiber, etc.
A lightweight molded product can be obtained by filling the core material with a resin sheet for lightweight composite material in a hollow shape or without gaps. As another molding method, a lightweight composite material resin sheet may be attached to a pre-cured molded plate made of prepreg such as carbon fiber, aramid fiber, or glass fiber, and then heat-cured. Furthermore, a reinforced plastic plate made of carbon fiber, aramid fiber, glass fiber, etc. and a cured resin sheet for lightweight composite materials can be heat-cured using a film adhesive.

In this way, the sheet material, which is an intermediate material for epoxy resin compositions for lightweight composite materials, can be easily laminated from flat plates to complex shapes, and can be used in the same way as structural adhesives by co-crosslinking with other prepregs. Moreover, it is easy to handle, and a lighter and stronger composite material can be obtained.

Examples of these uses include, in the aircraft industry, core materials for structures, filling complex-shaped objects, repairing holes, depressions, etc., and forming ducts. In sports, there are core materials for rackets, shafts, rods, poles, oars, paddles, boards, etc. In the field of civil engineering and construction, there are rods to replace rebar, furniture for upper floors, panels for walls, etc. In the medical field, there are core materials for helmets and wheelchair shafts, in vehicles such as automobiles, there are core materials for structural materials, and in the electrical field, there are housings for devices and equipment.

[Effects of the Invention] According to the present invention, a lightweight and strong composite material containing a foam can be obtained from an easy-to-handle lightweight composite material resin sheet or film.

[Examples and Comparative Examples] The present invention will be specifically explained below using Examples and Comparative Examples, but the present invention is not limited thereto.

Left-born Gokami Bisphenol A type epoxy resin (product name: Epicote 828) 2.8kg and phenol novolac type epoxy resin (product name: Epicote 154) 5.2kg
was fed into a planetary mixer and mixed uniformly at 120'C, followed by adding 1.2 kg of glass micro hollow spheres (trade name: Scotchlite Glass Bubbles C15/250, manufactured by Sumitomo 3M). Mix with After mixing, the contents were cooled to 70°C with stirring, and 0.24 kg of dicyandiamide was added as a hardening agent and 3-3 as a hardening accelerator.
p-chlorophenyl-1,1-dimethylurea 0,32
kg, azodicarbonamide 0.24 kg as blowing agent
Add quickly, stir for 5 minutes, remove and cool.

This blend was remelted at 70°C, and a sheet material with a thickness of 1.1 trm was obtained using a calendar roll coater. The produced sheet-like material was cut out and cured by heating in an oven at 130°C for 1 hour, resulting in a lightweight composite material with a thickness of 5 m. The density of the obtained foam is 0.3 g/am
"Met.

Ooku double bisphenol F type epoxy resin (product name: Epicoat 807) 3.0kg and orthocresol novolac type evo-gyu resin (product name: Epicoat 180S65)
5.0 kg was sent to a planetary mixer and heated to 130℃.
After uniformly mixing with
g and mix uniformly. Thereafter, the contents were cooled to 70°C with stirring, using 0.24 kg of dicyandiamide as a hardening agent, 0.32 kg of 3-(3,4-dichlorophenyl)-1-dimethylurea as a hardening accelerator, and 0.32 kg of toluene as a blowing agent. Quickly add 0.4 kg of sulfonyl hydrazide, stir for 5 minutes, draw out and cool. The mixture is remelted at 70°C and coated using a calender roll coater into a sheet with a thickness of 1.3++e. A foamed product was obtained.The produced sheet-like product was cut out and cured by heating in an oven at 130°C for 1 hour, and the density of the obtained foam was 0.3 g/cm''.

Except that no foaming agent or glass micro hollow spheres are used.
A sheet with a thickness of 1.7 m was obtained in the same manner as in Example 1.

The density of the cured product obtained by curing at 130°C for 1 hour was 1.
2 g/cm".

A sheet material having a thickness of 1.7 mm was obtained in the same manner as in Example 1, except that the double foaming agent was not used. The density of the cured product obtained by curing at 130°C for 1 hour was 0.6 g/cm''.

A sheet with a thickness of 1.7 days was obtained in the same manner as in Example 1, except that the Arashi Glossy Five-Element Glass Micro Hollow Spheres were not used.

The density of the cured product obtained by curing at 130°C for 1 hour is 0.
6 g/cm".

Two sheets of 300 x 300 trxtr square carbon fiber cloth prepreg were laminated on a stainless steel mold of 301 x 301 m 1 + square and 3.5 mm thick, and on top of that was the uncured sheet of 300 x 300 mm square obtained in Example 1. One sheet of 300 x 300 square carbon fiber cloth prepreg was laminated. A mold release film is applied to the upper and lower surfaces of these, and a stainless steel backing plate is placed on the outside of the release film, and the mold is placed in a hot press. After heating from room temperature to 130°C at a heating rate of 2°C/min, it was held at 130°C for 1 hour to foam and harden. The density of the obtained molded plate is 0.45
g/Cm" and was extremely lightweight regardless of its thickness. Next, from this molded plate, a length of 12C'ITl and a width of 1
．． Cut out a 5cm rectangular test plate and calculate the length/thickness ratio =
When a 3-point bending test was conducted under 30 conditions, the strength was 1.
4 kg/mm".

1. 301X 301-square, 3-thickness stainless steel mold
Two sheets of 00X 300-square carbon fiber cloth prepreg are laminated, and the 300X obtained in Example 1 is placed on top of the 300X carbon fiber cloth prepreg.
Two uncured sheets of 300 mm square are pasted, and further two sheets of 300 x 300 square carbon fiber cloth prepreg are laminated. A mold release film is applied to the upper and lower surfaces of these, and a stainless steel backing plate is placed on the outside thereof, and the mold is placed in a hot press. After heating from room temperature to 130°C at a heating rate of 2°C/+*in, it was held at 130°C for 1 hour to foam and harden.

The density of the obtained molded plate was 0.44 g/cm'', and it was extremely lightweight regardless of its thickness.The bending strength was 1.
The weight was 5kg10”.

The uncured sheet material obtained in Tomozumimitate Example 2 was
Cut into X401 squares, roll into a bar shape of external 1011I11, thickness O, L2m+a, 200X7
A 2 square unidirectional carbon fiber prepreg is wound, and then a release film of 220 x 40 mm square with a thickness of 0.05mm is wrapped over it, and both ends are sealed with heat-resistant tape. This was placed in an iron vibrator with an inner diameter of 12.5 m and a length of 200 cm, and both ends were closed with caps. Place this in an oven and raise the temperature from room temperature to 130°C at a rate of 2°C/rrin.
Thereafter, it was heated at 130° C. for 1 hour to foam and harden. The resulting molded rod had a density of 0.45 g/cm'' and was extremely lightweight regardless of its thickness.

Comparative Example 4 Two sheets of 300 x 300 mm square carbon fiber cloth prepreg were laminated on a 301 x 301 square, 3.5 mm thick stainless steel mold, and on top of that, the 300 x 300 mm square uncured prepreg obtained in Comparative Example 2 was laminated. One sheet-like material is pasted, and two 300 x 300 mm square carbon fiber cloth prepregs are further laminated. A mold release film is applied to the upper and lower surfaces of these, and a stainless steel backing plate is placed on the outside of the release film, and the mold is placed in a hot press. After heating from room temperature to 125°C at a temperature increase rate of 2°C/+in, it was held at 125°C for 1 hour to cure. The density of the obtained molded plate is 0.90 g/c
yn'', reaching twice the density of Example 3 in which a blowing agent was added.The bending strength was 17 kg/am''.

Patent applicant: Japan Petrochemical Co., Ltd.

Claims (1)

[Claims] (1) (A) epoxy resin, (B) micro hollow spheres, (C
1.) An epoxy resin composition for lightweight composite materials, comprising a blowing agent, (D) a curing agent, and (E) a curing accelerator. (2) Per 100 parts by weight of the composition, (A) 50 to 95 parts by weight of epoxy resin, (B) 5 to 35 parts by weight of micro hollow spheres, (C) 0.1 to 15 parts by weight of blowing agent, (D) Curing Agent 0.
The epoxy resin composition for lightweight composite materials according to claim 1, characterized in that the amount of the curing accelerator (E) is 5 to 10 parts by weight and 0.5 to 10 parts by weight. (3) A single intermediate material for a composite material, characterized in that the epoxy resin composition for a lightweight composite material according to claim 1 or 2 is molded into a sheet or film shape. (4) A lightweight composite material using the single intermediate material for composite materials according to claim 3. (5) The lightweight composite material according to claim 4, which is obtained by foaming and curing the single intermediate material for composite material. (6) A reinforcing intermediate material comprising the single intermediate material for composite materials according to claim 3 and a reinforcing material. (7) A lightweight composite material using the reinforcing intermediate material according to claim 6. (8) Claim 7 obtained by foaming and curing the reinforcing intermediate material.
Lightweight composite material as described.