JPH1036638A - Epoxy resin composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an epoxy resin composition suitable for composite materials, having low viscosity, excellent curability, excellent viscosity stability, excellent vibration damping performance, mechanical strength and heat resistance. . SOLUTION: (A) 2 to 15 parts by weight of rubber particles, (B)
40 to 90 parts by weight of an aliphatic epoxy resin, (C) 5 to 70 parts by weight of an epoxy resin other than the aliphatic epoxy resin, (D)
It is composed of an acid anhydride which is liquid at normal temperature, and the weight ratio of (B) to the resin components (A) to (C) is 0.4 to 0.4.
It is an epoxy resin composition of 0.9.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an epoxy resin composition suitable for a fiber-reinforced composite material (hereinafter referred to as "FRP") having a low viscosity, excellent curability, and excellent viscosity stability. The present invention relates to an epoxy resin composition having excellent vibration damping performance, mechanical strength and heat resistance and suitable for composite materials.

[0002]

2. Description of the Related Art An FRP in which a matrix resin is reinforced with reinforcing fibers takes advantage of light weight, high elasticity, and high strength.
It is widely used in various applications such as structural materials for aircraft, ships, automobiles and the like, or industrial materials such as rolls, and sports applications such as fishing rods, golf shafts and tennis rackets.

[0003] In recent years, in addition to the above-mentioned mechanical properties such as lightweight, high strength and high elasticity, FRP has been improved in vibration absorbing performance at the time of hitting for sports use, and has improved soundproofing performance and torque transmission in industrial use. There is a demand for characteristics (vibration suppression performance) for suppressing vibration such as low vibration of a shaft.

[0004] The vibration damping performance of a vibrating body is expressed by the following formula: when the amplitudes of adjacent vibrations in a damped sine waveform are X ₁ and X ₂ , respectively.
The greater the logarithmic decrement △ represented by the following equation (1), the more excellent vibration damping performance can be obtained.

△ = In (X ₁ / X ₂ ) (1)

The logarithmic decay rate is represented by the following equation (2) using the loss coefficient η.

Δ = πη (2) Therefore, it can be said that the larger the loss coefficient η, the better the vibration damping performance.

As a vibration damping composition for forming a vibration damping material capable of efficiently attenuating vibrations, a composition containing a polyamide resin or a polyvinyl chloride resin as a main component has conventionally been used.

However, a vibration damping material molded from a composition for a vibration damping material containing a polyamide resin as a main component is inferior in water resistance and chemical resistance, and has low mechanical strength. It is difficult to form a damping material with a complex shape using a polyvinyl chloride-based resin as a main component. There was a problem of becoming.

[0010] As a method of giving vibration damping properties to FRP,
The method can be broadly divided into a method based on structural design such as optimization of reinforcing fibers and a lamination structure, and a method based on improvement of a matrix resin. The former method is intended to impart damping performance to the structure itself, but generally, a material having high rigidity that can be a structure has low damping performance, and a material having high damping performance has low rigidity. The latter method is intended to improve vibration damping performance by changing vibration energy into heat energy using a matrix resin.

The former method is disclosed in Japanese Unexamined Patent Publication No.
No. 67 discloses a method of improving vibration damping performance by using aramid fiber or polyarylate fiber as a reinforcing fiber, but the FRP obtained by this method is difficult to perform post-processing such as drilling. There's a problem.

Japanese Patent Application Laid-Open No. 3-274143 discloses a method of forming an FRP having excellent vibration damping performance by laminating a glass cloth on a sheet-like viscoelastic material, preforming the same, and then impregnating with a thermosetting resin. Is disclosed. However, this molding method requires complicated two-stage molding, and is difficult to apply to molding general-purpose products such as sports applications in terms of cost.

In addition, a method of improving vibration damping performance by applying an elastic paint to the surface, devising the shape and structure of the racket, and absorbing vibration by resonating different vibrations when an impact is applied. The method is known,
Nothing yet can meet the market demands.

As a method for improving the vibration damping performance by improving the matrix resin, a polyhydric alcohol and a polyisocyanate compound are reacted in the presence of a reinforcing fiber as disclosed in JP-A-2-86615. However, the obtained FRP may not provide the rigidity required for sports applications.

Further, by utilizing the property that the matrix resin has a large loss coefficient η near the glass transition point, an amorphous epoxy resin and a low molecular weight organic filler having a low glass transition temperature (so-called plasticizer) may be blended. Are known. However, such epoxy resin-based damping materials have a high mechanical strength, and when trying to obtain a material with excellent durability and moldability, the vibration-damping performance decreases, and a material with excellent vibration-damping performance is obtained. In such a case, there is a problem that the mechanical strength is low and the heat resistance and the moldability are inferior.

Incidentally, as a method of forming the FRP, in addition to a method of using an intermediate material in which a matrix resin called a prepreg is impregnated in a reinforcing fiber, a hand lay-up method, a filament winding (hereinafter, referred to as FW) method, a resin transfer method, and the like. Molding (hereinafter referred to as RTM) method, injection (RIM)
Method, FW method without prepreg, RT
The M method and the RIM method are widely used as low-cost molding methods.

The resin properties applicable to these molding methods are not only excellent in mechanical properties after molding, but also low enough to be injected into a mold in which reinforcing fibers are arranged, and curing. It is required that the resin has excellent properties and the stability of the viscosity is excellent. However, a resin satisfying various performances required for molding and vibration damping performance after curing has not yet been known.

[0018]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and has been made by a hand lay-up molding method.
It can be used particularly suitably for molding methods, RTM molding methods, etc., and can be molded at a relatively low temperature in a short time, so that the productivity improving effect is very high.
It is an object to provide an epoxy resin composition and a fiber-reinforced composite material having excellent heat resistance and mechanical strength.

[0019]

The gist of the present invention is that (A)
2 to 15 parts by weight of rubber particles, (B) aliphatic epoxy resin 4
0 to 90 parts by weight, (C) 5 to 70 parts by weight of an epoxy resin other than the aliphatic epoxy resin, (D) an acid anhydride-based curing agent which is liquid at room temperature, and (A) to (C) An epoxy resin composition wherein the weight ratio of (B) to the components is 0.4 to 0.9.

[0020]

BEST MODE FOR CARRYING OUT THE INVENTION The rubber particles (hereinafter, simply referred to as (A)) used in the present invention are rubbers having a partially crosslinked structure inside a rubber component, and include butadiene rubber,
A particle such as an acrylic rubber can be exemplified, but is not limited thereto.

The at least partially crosslinked rubber particles used as (A) may be singly mixed with the resin composition, but epoxy resins other than the aliphatic epoxy resins described below (hereinafter simply referred to as (C)). The epoxy resin may be used after it is dispersed and mixed or dispersed beforehand to partially react with the epoxy resin.

As described above, it is preferable to add (A) and (C) by preliminarily preliminarily reacting them from the viewpoint of improving vibration damping properties. Although this mechanism has not been elucidated yet, it is presumed that it is important that the terminal group of the rubber component and the epoxy resin are partially bonded. The epoxy resin obtained by reacting (A) and (C) can be easily prepared by reacting a mixture of (A) and (C) at a temperature of 100 ° C. to 180 ° C., optionally adding a catalyst. Obtainable.

Examples of the crosslinked rubber-modified epoxy resin which is commercially available as a reactant of (A) and (C) or is available as a sample include Epicron TSR-960 and TSR-601 of Dainippon Ink and Chemicals, Nippon Shokubai. CX-M
Examples of the N series include crosslinked rubber-modified epoxy resins manufactured by Nippon Synthetic Rubber Co., Ltd., but are not limited thereto.

(C) used in the present invention is a liquid at room temperature,
There is no particular limitation unless it is aliphatic, but bisphenol A
A commercially available epoxy resin such as a type epoxy resin, a bisphenol F type epoxy resin, a bisphenol S type epoxy resin, a phenol novolak type epoxy resin, and a glycidylamine type epoxy resin can be used. It can be used appropriately according to the purpose. Although one type of epoxy resin may be used as (C), two or more types of epoxy resins may be mixed and used as needed.

The viscosity of (C) is preferably 200 poise or less at room temperature, more preferably 100 poise or less, due to problems such as handleability during molding. When the viscosity at room temperature is within this range, hand lay-up molding, RTM molding,
In the case of molding by the FW molding method, it is very difficult to handle and a molded product having good surface properties cannot be obtained.

The epoxy resin (C) may be mixed with a reaction diluent or the like to adjust the viscosity to the above value before use.

The aliphatic epoxy resin (hereinafter simply referred to as (B)) used in the present invention includes ethylene glycols, propylene glycols, butylene glycols,
Neopentyl glycols, 1,6 hexanediols, di (6-hydroxyhexyl) ether, 1,8-
Octanediol, di (8-hydroxyhexyl) ether, 1,10-decanediol, di (10-hydroxydecyl) ether, phenyleneethylene glycol,
2-1 carbon atoms such as di (phenylethylene glycol)
Triglycidyl ethers of pentaerythritol, such as glycidyl ethers of polyols 5, glycerol triglycidyl ether, polyglycerol polyglycidyl ether, and trimethylolpropane glycidyl ether, such as triglycidyl ether of propylene oxide adduct of trimethylolpropane. Glycidyl ether-type epoxy resins obtained by glycidylation of hydrogenated bisphenols such as ether, glycidyl ester-type epoxy resins obtained by glycidylation of hexahydrophthalic anhydrides, tetrahydrophthalic anhydrides, dimer acids, benzoic acids, and the like can be given.

(B) The aliphatic epoxy resin preferably has a low viscosity, preferably 100 poise or less at room temperature and 25 ° C., more preferably 50 poise or less.

In the epoxy resin composition of the present invention, the above-mentioned (A), (B) and (C) are mixed in proportions of 2 to 15 parts by weight, 40 to 90 parts by weight and 5 to 70 parts by weight, respectively. It is necessary that the weight ratio of (B) to the resin components of (A) to (C) is 0.4 to 0.9.
More preferred weight ratios of (A), (B) and (C) are 2 to 10 parts by weight, 50 to 80 parts by weight and 10
５０50 parts by weight.

When the amount of the component (A) is larger than the above range, the viscosity of the matrix resin becomes high because a large amount of the component (A) of the fine powder is blended, and the matrix resin can be applied to molding methods such as FW and RTM. It will be difficult. If (B) is less than 40 parts by weight, sufficient vibration damping properties cannot be obtained, and if it exceeds 90 parts by weight, sufficient mechanical strength and heat resistance for use as FRP cannot be obtained. If (C) is outside the above range, the obtained FPR cannot have sufficient mechanical strength and heat resistance.

Further, in the present invention, (A) and (B)
It is necessary that the weight ratio of (B) in the resin component consisting of (C) and (C) is 40 to 90% by weight.
More preferably, it is in the range of 0 to 80% by weight.

The epoxy resin composition of the present invention comprises (A)
By mixing (B) and (C) at the above ratio, low viscosity and sufficient vibration damping performance and mechanical strength and heat resistance as FRP applicable to molding methods such as RTM method or FW method. Is obtained in a well-balanced manner.

The acid anhydride-based curing agent liquid (D) at room temperature is not particularly limited, but tetrahydrophthalic anhydride, methyltetrahydrophthalic anhydride, methylhexahydrophthalic anhydride, methylnadic anhydride, dodecyl anhydride Succinic acid is preferably used, and one or more acid anhydride-based curing agents selected from these are used alone or in combination with two or more.
It is preferable to use a mixture of two or more kinds. The amount added is preferably 50 to 120%, more preferably 70 to 100% of the stoichiometric amount of the epoxy resin component (a mixture of (A) and (B)).

[0034] A curing accelerator may be further added to the epoxy resin composition of the present invention. The curing accelerator that can be suitably used here is preferably a liquid at room temperature, or a liquid that liquefies with a slight heating, or a substance having a melting point lower than the curing temperature or a substance that dissolves in the resin composition. More preferably, the melting point is 60 ° C. or lower. In terms of chemical structure, it is more preferable to have active hydrogen at the 1-position from the balance between stability and reactivity of the obtained resin composition.

As such a curing accelerator, imidazoles are preferable, and 2-ethyl-4-methylimidazole is most preferably used.

The amount of the curing accelerator to be added is (A)
It is preferably in the range of 0.5 to 5 parts by weight based on 100 parts by weight of the resin components of (B) and (C),
More preferably, it is 3 parts by weight.

Since the epoxy resin composition of the present invention has a very low viscosity and excellent impregnation properties, hand lay-up, FW, R
Since it is particularly suitably used as a matrix resin applied to TM and can be molded at a relatively low temperature in a short time, the effect of improving productivity is very high, and the obtained FRP has excellent heat resistance and mechanical properties.

In the epoxy resin composition of the present invention,
The cured resin cured at 120 ° C. for one hour preferably has an intrinsic damping ability of 35% or more. This intrinsic damping capacity is 3
If it is less than 5%, sufficient vibration damping tends not to be obtained when FRP is used.

In the present invention, the intrinsic decay ability is measured as follows. 150m from cured resin plate
A test piece of m length x 12.5 mm width x 0.9 mm thickness was cut out, 30 mm cantilever was fixed from one end, and a 35 g weight from a height of 50 cm was dropped and impacted on the tip to measure the vibration damping behavior. Is converted into an electric signal by a strain gauge attached at a position 50 mm from one end fixed to the cantilever and measured. From the obtained attenuation waveform, the intrinsic attenuation power is obtained based on the following equation.

Δ = 1 / n · In (A ₀ / A _n ) A ₀ : magnitude of amplitude immediately after impact A _n : magnitude of n-th amplitude after impact D. C. (%) = (1−δe ⁻² ) × 100

[0041]

The present invention will be described in more detail with reference to the following examples. Abbreviations of the compounds in the examples and comparative examples, and the test methods are as follows.

Acrylic rubber particles: Particle size: 0.2 μm Ep828; Epicoat 828 Bisphenol A type epoxy resin (manufactured by Yuka Shell Epoxy) EP807: Epicoat 807 Bisphenol F type epoxy resin (manufactured by Yuka Shell Epoxy)

BPA328: A reaction product of an acrylic rubber having a crosslinked structure and a bisphenol A type liquid epoxy resin. Estimated rubber content = 20% (Nippon Shokubai Co., Ltd.) PG-207: polypropylene glycol diglycidyl ether (manufactured by Toto Kasei Co., Ltd.)

PT-2PG: Long-chain dibasic acid glycidyl ester (manufactured by Okamoto Oil Co., Ltd.) YH-300: Epotote YH-300 trifunctional aliphatic polyglycidyl ether (manufactured by Toto Kasei Co., Ltd.)

THPE: Tetrahydrophthalic anhydride ET-100: Ethacure 100 (Ethyl Corporation)

XN-1045: acid anhydride curing agent (Ci
ba Geigy) 2E4MZ: 2-ethyl-4-methylimidazole (Shikoku Chemicals)

(TMA-Tg) The epoxy resin composition of each composition was cured at 120 ° C. for 1 hour to obtain a cured resin plate. A test piece was cut out from the resin plate, and TM was used under the conditions of an expansion mode (load 1 g) and a temperature rising rate of 10 ° C./min using 943TMA manufactured by TA Instruments.
A-Tg was measured.

(RTM Molding Evaluation) After heating a cylindrical mold in which a CF sleeve was previously arranged to 120 ° C., an epoxy resin composition adjusted by a method described later was injected. After one hour, the molded product was taken out, and the surface state of the molded product and a cross section cut and polished at right angles to the carbon fiber woven fabric were observed.

Good: The surface is smooth, the acrylic rubber is uniformly dispersed in the cross-section by microscopic observation, and no voids or cracks are observed between the layers.

Poor: There are pinholes on the surface, and voids and cracks are observed between layers in a microscopic observation of the cross section.

(Measurement of Vibration Suppression) Intrinsic damping capacity (SD
C. ) Was measured as follows. From the cured resin plate, cut out a test piece of 150 mm length x 12.5 mm width x 0.9 mm thickness, grabbed 30 mm from one end and fixed cantilevered,
Vibration damping behavior caused by dropping and hitting a weight having a height of 50 cm to 35 g at the tip is measured by an electric signal using a strain gauge attached in the longitudinal direction at 50 mm (20 mm from the grip) from the cantilevered end of the test piece. And measured. From the obtained attenuation waveform, the intrinsic attenuation ability was obtained based on the following equation.

Δ = 1 / n · In (A ₀ / A _n ) A ₀ : magnitude of amplitude immediately after impact _An : magnitude of n-th amplitude after impact D. C. (%) = (1−δe ⁻² ) × 100

(FRP Three-Point Bending Test) Epoxy resin compositions of each composition were prepared using carbon fiber TR-
40, 3,000 filaments were impregnated into a cloth TR3110 of a carbon fiber woven fabric with a basis weight of 200 g / m ² woven at 12.5 filaments / inch both in the course and at 120 ° C.
Pressure in a press machine heated to 1 kgf / cm ² , time:
It was cured and molded in one hour to obtain an FRP plate (volume content of carbon fiber: 40% by volume). A test piece was cut out from the FRP plate and subjected to a three-point bending test according to ASTM D790-81.

(Examples 1 to 22, Comparative Examples 1 to 6)
(A), (B), (C) and (D) were uniformly mixed with (A) and (C) according to the composition shown in Table 1, and then (B) and (D) were added and mixed uniformly. did.

30 ° C. of the epoxy resin composition thus obtained
, RTM moldability, S.P. D. C. , FRP3
The point bending strength, elastic modulus and TMA-Tg were evaluated and are shown in Tables 1 and 2.

[0056]

[Table 1]

[0057]

[Table 2]

[0058]

The epoxy resin composition of the present invention has a low viscosity, has excellent curability, has excellent viscosity stability, and has excellent vibration damping performance, mechanical strength and heat resistance, and is suitable for composite materials. A composition.

Claims (3)

[Claims] (A) 2 to 15 parts by weight of rubber particles, (B)
40 to 90 parts by weight of an aliphatic epoxy resin, (C) 5 to 70 parts by weight of an epoxy resin other than the aliphatic epoxy resin, (D)
It is composed of an acid anhydride-based hardened liquid at normal temperature, and the weight ratio of (B) to the resin components (A) to (C) is 0.4 to 0.4.
An epoxy resin composition which is 0.9. 2. The epoxy resin composition according to claim 1, wherein the resin cured at 120 ° C. for 1 hour has an intrinsic damping ability of 35% or more. 3. The epoxy resin composition according to claim 1, wherein (A) the rubber particles and (C) an epoxy resin other than the aliphatic epoxy resin are preliminarily reacted.