JPH09216958A - Prepreg - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a prepreg improved in vibration-damping properties, impact resistance, and interlayer shear strength by impregnating a fibrous reinforcement with a mixture comprising an epoxy resin, a hardner, a cure accelerator, and a particulate ethylene copolymer resin. SOLUTION: A resin compsn. comprising 100 pts.wt. epoxy resin having a viscosity of 0.1-300 P, 1-10 pts.wt. hardner, and 1-10 pts.wt. cure accelerator is mixed with 1-80vol.% particulate ethylene copolymer resin having an elastic modulus of 10-900Mpa, a polar monomer content of 5-50wt.%, and an average particle size of 0.01-50μm. The resultant mixture is heated to a temp. in the range of 50-90 deg.C and not higher than the m.p. of the copolymer resin and then impregnated into a fibrous reinforcement, thus giving a prepreg having an interlayer shear strength of 5-20kgf/mm<2> , a bending strength of 100-300kgf/mm<2> , and a bending modulus of 10-30tf/mm<2> .

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a prepreg, in particular, a fiber reinforced plastic (FRP) having excellent vibration damping properties (vibration damping properties) and mechanical properties such as flexural strength, flexural modulus and interlaminar shear strength. It also relates to excellent prepreg.

[0002]

2. Description of the Related Art A composite material composed of a reinforcing fiber such as carbon fiber, glass fiber, aromatic polyamide fiber and an epoxy resin is excellent in specific strength and specific elastic modulus. Widely used in fields such as sports equipment used in premier sports such as fishing rods, tennis rackets, skis, and rims of competition bicycles, structural materials for aircraft, civil engineering materials, industrial rolls, speaker materials, etc. .

Composite materials used in these fields include:
All of these require properties such as light weight and high rigidity, and also require high vibration damping properties in order to secure the stability of motion and reduce the impact on the human body. It has been proved that the vibration damping property is improved by using the pitch type carbon fiber as the carbon fiber of the carbon fiber reinforced plastic, but it cannot be said that the vibration damping property is sufficient.

Further, conventionally, a composition having an energy converting function, which contains a piezoelectric material in the form of fine particles and a conductive material or a semiconductive material, is used, and vibration energy is finally transferred via electric energy. A method of exhibiting a vibration damping effect by converting the heat energy into heat energy and dissipating the heat energy is already known, and is disclosed in JP-B-61-46498, JP-A-61-8365, and JP-A-62-255135.
JP-A No. 63-20362 and the like.

However, these methods have a problem in that a large amount of piezoelectric material must be added in order to exert vibration damping properties, and the weight of the piezoelectric material used is high, so that weight reduction cannot be achieved.

Japanese Examined Patent Publication No. 1-25702 and Shokai Sho 6
Japanese Patent Laid-Open No. 4-46221 discloses a damping material in which a high elastic modulus resin and fiber layer and a resin and fiber layer having high vibration damping characteristics are laminated. However, although these materials have improved vibration damping properties, they have a problem that mechanical properties such as interlaminar strength are significantly reduced.

JP-A-63-162732, JP-A-63-170427 and JP-A-63-1704
Japanese Patent Publication No. 28 discloses a resin composition in which thermoplastic resin particles such as polyamide particles, polycarbonate particles, and polyethylene particles are added to a thermosetting resin such as an epoxy resin as an impact resistance improver. However, so-called engineering plastics such as polyamide fine particles and polycarbonate fine particles have a low effect of improving the damping property of the resin composition, and in the case of polyethylene fine particles, the compatibility with the thermosetting resin is poor, so that the resin composition such as interlayer strength There is a problem that other physical properties are easily deteriorated.

An object of the present invention is to provide a prepreg excellent in vibration damping property, impact resistance and interlayer toughness when used as an FRP.

[0009]

In order to achieve this object, the prepreg of the present invention comprises a reinforcing fiber, a mixture of an epoxy resin, a curing agent and a curing accelerator impregnated therein, and a distribution in the mixture. The ethylene copolymer resin particles thus prepared are provided. Here, usually, the ethylene copolymer resin particles are distributed closer to the surface than inside the prepreg.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below. Examples of the epoxy resin used in the present invention include bisphenol A type epoxy resin, bisphenol F type epoxy resin, phenol novolac type epoxy resin, cresol novolac type epoxy resin, glycidyl amine type epoxy resin and glycidyl ester type epoxy resin, and mixtures thereof. Is mentioned.

Examples of the bisphenol A type epoxy resin include Epicoat 825 and Epicoat 828 (both manufactured by Yuka Shell Epoxy Co., Ltd.).

As the bisphenol F type epoxy resin, Epicoat 807 (produced by Yuka Shell Epoxy Co., Ltd.), Epotote YDF170 (produced by Toto Kasei Co., Ltd.), Epicron 830
(Manufactured by Dainippon Ink and Chemicals, Inc.), EP-4900 (manufactured by Asahi Denka Co., Ltd.), PY-306 (manufactured by Asahi Ciba), and the like are commercially available.

Examples of the phenol novolac type epoxy resin are Epicoat 152, Epicoat 154 (all manufactured by Yuka Shell Epoxy Co., Ltd.), and Epotote YDPN638.
(Manufactured by Toto Kasei Co., Ltd.) and the like.

Examples of cresol novolac type epoxy resins include YDCN-701 and YDCN-702 (both manufactured by Toto Kasei Co., Ltd.), and glycidylamine type epoxy resins include Sumiepoxy ELM100 and Sumiepoxy ELM434 (both manufactured by Sumitomo Chemical Co., Ltd.). ) And the like.

Examples of the glycidyl ester type epoxy resin include Epicoat 190P and Epicoat 191P (both manufactured by Yuka Shell Epoxy Co., Ltd.).

The viscosity of the epoxy resin used is usually 0.1.
~ 300 poise, preferably 1-200 poise
It is.

Dicyandiamide is preferably used as the curing agent in the present invention, and in consideration of the curability and storage stability of the epoxy resin composition, the epoxy resin 10
1 to 10 parts by weight, preferably 2 to 0 parts by weight
Used in the range of 8 parts by weight.

As the curing accelerator used in the present invention, a urea derivative is generally used. Specific preferred urea derivatives include phenyldimethylurea and 3- (4
-Chlorophenyl) -1,1 dimethylurea, 3- (3,
4-dichlorophenyl) -1,1 dimethylurea (DC
MU) and the like.

The amount of the curing accelerator used is usually 1 to 10 parts by weight, preferably 2 to 8 parts by weight, based on 100 parts by weight of the epoxy resin in consideration of the curability and storage stability of the epoxy resin. It

The ethylene copolymer resin particles used in the present invention are particles having a suitable adhesiveness with the matrix resin (epoxy resin), and therefore, the interlayer strength and tensile strength of the FRP molded by the prepreg are lowered. Less is.

The elastic modulus of the ethylene copolymer resin particles used is 10 to 900 MPa, preferably such that when the resin composition when mixed with the matrix resin is formed into a molded body, the molded body has vibration damping properties. 50 to 500MP
a, more preferably 80 to 300 MPa.

The ethylene copolymer resin particles are preferably in the form of particles of a copolymer resin of ethylene and another polar monomer.

The polar group of the ethylene copolymer resin particles is preferably a chlorine substituent, a carboxyl group, an ester group or a hydroxyl group.

Specific examples of the ethylene copolymer resin particles include ethylene acrylic acid copolymer resin particles, ethylene acrylic acid ester copolymer resin particles, ethylene vinyl alcohol copolymer resin particles, and ethylene vinyl acetate copolymer resin particles. , Ethylene vinyl chloride copolymer resin particles, modified ethylene vinyl acetate copolymer resin particles, ethylene vinyl acetate vinyl chloride graft polymer resin particles, chlorinated polyethylene having the same structure as the copolymer, and the like, Most preferably, ethylene acrylic acid copolymer resin particles are used.

Among these ethylene copolymer resin particles, those having a proper affinity for the epoxy resin, that is, the content of the polar group monomer copolymerized with ethylene is usually 5 to 50% by weight, preferably 5 ~ 20 wt% resin particles are used. Here, the content of the polar monomer copolymerizable with ethylene means acrylic acid for ethylene acrylic acid copolymer resin, vinyl acetate for ethylene vinyl acetate resin, ethylene-vinyl chloride copolymer resin, etc. It means the content of vinyl chloride.

Specific examples of commercially available ethylene acrylic acid copolymer resin particles include Flow Bead EA-20.
9 (Sumitomo Seika, melting point 105 ° C, acrylic acid content 7
% By weight.

The average particle diameter of the ethylene copolymer resin particles is not particularly limited, but in consideration of moldability, it is usually 0.01 to 50 μm, more preferably 0.01.
˜40 μm, most preferably 0.01 to 10 μm.

When the ethylene copolymer resin particles are not available as a commercial product, the ethylene copolymer resin is pulverized, or the ethylene copolymer resin is dissolved by using a solvent and spray-dried or precipitated. It can be obtained by a method of forming particles by a method or the like.

The content of the ethylene copolymer resin particles is not particularly limited, but is based on the total of the epoxy resin, the curing agent, the curing accelerator and the ethylene copolymer resin particles which are the constituents of the prepreg. It is preferably 1 to 80% by volume, more preferably 20 to 60% by volume. Within these ranges, the optimum amount can be appropriately selected depending on the desired damping properties and the manifestation of mechanical properties.

The mixing method of each component is not particularly limited. For example, since the epoxy resin and the ethylene copolymer resin particles have a high affinity and the particles are easily dispersed in the epoxy resin, they are mixed at 20 ° C. or higher. A method may be used in which the particles are heated to a temperature below the melting point of the particles and mixed, and then a curing agent and a curing accelerator are added to the mixture and mixed. Moreover, after mixing the epoxy resin, the curing agent and the curing accelerator, the mixture is heated to a temperature of 20 ° C. or higher and a curing temperature or lower, preferably 20 ° C. or higher and 90 ° C. or lower, and ethylene copolymer resin particles are added thereto. There is also a method of adding and mixing.

The epoxy resin and the ethylene copolymer resin particles usually have a high affinity, but if the affinity is low and it is difficult to disperse them, they are heated to a temperature not lower than the melting point of the ethylene copolymer resin particles and not higher than 200 ° C. It is also possible to mix them.

Further, it is in a liquid state at 20 ° C., preferably with a curing agent, a curing accelerator and ethylene copolymer resin particles, preferably at 20 ° C.
After mixing a part or all of the epoxy resin having a viscosity of 20 poise or less with a roll, preferably with three rolls, this may be mixed with the remaining epoxy resin while heating to a predetermined temperature. Usually, the curing agent, the curing accelerator and the ethylene copolymer resin particles are used in a state of being dispersed as particles in the epoxy resin.

The reinforcing fiber used in the prepreg of the present invention is not particularly limited, and examples thereof include carbon fiber, glass fiber, aromatic polyamide fiber, boron fiber, silicon carbide fiber, alumina fiber, potassium titanate fiber and the like. These mixed yarns can be used, and the form of the prepreg according to the present invention can be a non-woven fabric prepreg, a unidirectional prepreg or a woven prepreg. The volume content of reinforcing fibers in prepreg is usually 4
It is 0 to 90%, preferably 50 to 80%.

The method for producing the prepreg of the present invention by impregnating the reinforcing fiber with a resin composition in which an epoxy resin, a curing agent, a curing accelerator and ethylene copolymer resin particles are mixed is not particularly limited, but the above resin is used. The composition is usually 50 to
A so-called hot melt method in which the reinforcing fibers are impregnated by heating at 90 ° C. and a temperature lower than the melting point of the ethylene copolymer resin particles is preferably adopted.

Ethylene copolymer resin particle size is 0.1 μm
In the case of the above, the ethylene copolymer resin particles are distributed at a higher concentration on the prepreg surface than in the prepreg. This is because when the reinforcing fiber is impregnated with the resin composition, the ethylene copolymer resin particles having a particle size of 0.1 μm or more cannot pass through the gaps between the reinforcing fibers to reach the inside of the reinforcing fibers, This is because most of them remain on the surface of the reinforcing fiber.

When the prepreg is produced, the reinforcing fiber is first impregnated with components (epoxy resin, curing agent and curing accelerator) other than the ethylene copolymer resin particles,
It is also possible to add ethylene copolymer resin particles having a particle diameter of 0.1 μm or more to the surface of the prepreg to obtain a prepreg in which the particles as described above are distributed at a high concentration on the surface of the prepreg. At this time, the method for adding the ethylene copolymer resin particles to the prepreg is preferably a method in which the resin particles are dispersed in a solvent such as alcohol to form a slurry, and the slurry is applied to the prepreg with a roller or the like. You can

In the prepreg thus obtained,
A portion other than ethylene constituting the ethylene copolymer resin particles of the resin composition, for example, in the case of ethylene acrylic acid copolymer resin particles, since the acrylic acid portion has an affinity with the epoxy resin which is the matrix resin, the prepreg is cured. The mechanical properties of the molded product obtained by molding are usually such that the interlaminar shear strength is 5 to 20 kgf / mm ² , and the bending strength is 100 to 30.
0 kgf / mm ² , flexural modulus 10-30 tf / mm
² and so on.

Furthermore, since the ethylene copolymer resin particles have a lower elastic modulus than so-called engineering plastic particles such as polyimide resin particles, the logarithmic decrement is usually 0.05 to 0.5 and excellent in damping property. A molded body can be obtained.

The above-mentioned interlaminar shear strength is ASTM D2.
344-84, bending strength, and bending elastic modulus are measured according to JIS K7074-88 by three-point bending, and the vibration damping property is measured in the vibration damping characteristic test method of JIS G0602 damping steel plate. It is based on the one-end fixation and impact vibration method, and the initial displacement is given by vibration by hand.
The same applies to the following embodiments.

[0040]

EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited thereto.

Example 1 Bisphenol A type epoxy resin (Epicoat 828:
60 parts by weight of Yuka Shell Epoxy Co., Ltd.) was mixed with 40 parts by weight of a phenol novolac type epoxy resin (Epotote YDPN638: manufactured by Toto Kasei Co., Ltd.), 4 parts by weight of dicyandiamide and 6 parts by weight of DCMU to obtain a mixed resin composition. Ethylene acrylic acid copolymer resin particles (FlowBeads EA-209, manufactured by Sumitomo Seika Chemical Co., Ltd.) were further added to this mixed resin composition, and the volume was adjusted to 50% by volume. This particle-mixed matrix resin was applied onto release paper using a reverse roll coater to obtain a resin film. Next, this resin film was supplied from the top and bottom of carbon fibers (T700 manufactured by Toray Industries, Inc.) aligned in one direction to impregnate them to prepare a prepreg having a fiber volume content of 60%. The amount of carbon fiber per unit area of this prepreg is 1
90 g / m ² , the amount of matrix resin containing particles is 70
g / m ² . Laminate this prepreg in one direction,
When this is autoclaved, the pressure is 7 kg / cm.
² Hold at 130 ℃ for 2 hours, then laminate (CFR
P plate) was obtained. This laminated plate was made into a cantilever shape of 25 mm x 260 mm, the vibration damping after applying initial displacement to this was read by a non-contact sensor, and the peak of the damping curve obtained was approximated by an exponential function to logarithmic damping. The rate was evaluated. As a result, the logarithmic decrement was 0.11. When the physical properties of the laminate were measured, the physical properties at 25 ° C. were 0 ° bending strength of 140 kgf / mm ² , 0 ° bending elastic modulus of 1
3.0tf / mm ² , interlaminar shear strength (ILSS) 9k
gf / mm ² .

Comparative Example 1 Unidirectional prepreg T700 / # 2500 (Torayca: P3)
052S-12) was laminated in one direction, and this was held in an autoclave at a pressure of 7 kg / cm ² and 130 ° C. for 2 hours to produce a laminated plate (CFRP plate). 60% fiber volume content of the prepreg, a carbon fiber weight per unit area of 125 g / m ^2, the amount of the resin was 62 g / m ^2.
When the logarithmic decay rate of this laminated plate was measured in the same manner as in the example, the logarithmic decay rate obtained was 0.009. The physical properties of this laminate at 25 ° C. are as follows: 0 ° bending strength is 160 kgf / mm ² , 0 ° bending elastic modulus is 15.
0tf / mm ² , interlaminar shear strength (ILSS) is 10kg
f / mm ² .

Comparative Example 2 In the same manner as in Example 1 except that polyamide fine particles (Organsol 2002 EDX, manufactured by Nippon Rilsan Co., Ltd., average particle size 8 to 12 μm) were used in place of the ethylene acrylic acid copolymer resin particles. A prepreg was produced to obtain a laminated board.
When the logarithmic decay rate of this laminated plate was measured in the same manner as in Example 1, the logarithmic decay rate was 0.03.

As described above, the laminated plate made of the prepreg of Example 1 has high bending strength, bending elastic modulus and interlaminar shear strength, and has extremely excellent vibration damping property as compared with the FRP made of the prepreg of Comparative Example 1. I understand. Further, it can be seen that the laminated plate of Example 1 has a good attenuation rate as compared with Comparative Example 2.

[0045]

As described above, according to the prepreg of the present invention, the FRP molded by the prepreg has excellent vibration damping properties and good physical properties.

Claims (1)

[Claims] 1. A reinforcing fiber, a mixture of an epoxy resin, a curing agent thereof and a curing accelerator impregnated therein, and ethylene copolymer resin particles distributed in the mixture. Prepreg to do.