JPH09137044A - Epoxy resin composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an epoxy resin composition, having a temperature for stably maintaining a low viscosity for a long period, a small shrinking stress when cured, hardly causing cracking in a cured molding product and suitable for use as a matrix resin in the molding product according to especially a resin transfer molding (RTM) molding method. SOLUTION: This epoxy resin composition comprises 100 pts. by wt. bisphenol type epoxy resin, 50-250 pts. by wt. bifunctional epoxy resin having a naphthalene skeleton, 5-60 pts. by wt. cross-linked rubber fine particles having <=0.5μm particle diameter and a curing agent and is capable of maintaing <=10P viscosity for >=2hr.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to an epoxy resin composition suitable for use as a matrix resin for a fiber-reinforced composite material mainly called FRP or composite.

[0002]

2. Description of the Related Art A cured epoxy resin-formed product has excellent mechanical properties and electrical properties, and FR using the epoxy resin as a matrix resin for a fiber-reinforced composite material.
Molded products called P or composites are used in a wide range from aircraft to shafts for fishing rods and golf clubs. Further, the epoxy resin has excellent adhesive properties and the like, and is used, for example, as a sealing material for electronic materials, a paint, a paving material, and the like.

As a molding method of the above FRP molded body, a resin transfer molding method (RTM molding method) has recently attracted attention. This RTM molding method is a method of obtaining a target molded article by loading a preform as a fiber reinforcement into a mold, and then injecting and curing a resin into the mold, which has high productivity and is generally used. It is excellent in that a composite material reinforced in the thickness direction, which cannot be obtained by the above-mentioned lamination method, can be obtained.

The characteristics required for the matrix resin for the molded product by the above RTM molding method are that it has a low viscosity and is stable for a long time, and that the shrinkage stress at the time of curing is small and cracks are hard to occur in the cured molded product. Is.

By the way, in a thermosetting resin, when the atmospheric temperature rises, the initial viscosity decreases, but the viscosity increasing speed increases. On the contrary, when the atmospheric temperature decreases, the viscosity increasing rate slows down and the stability is maintained, but the viscosity level increases to an extent unsuitable for molding. On the other hand, the matrix resin of the molded body produced by the above RTM molding method is 10
It is necessary to have a viscosity of poise or less and to keep the viscosity of 10 poise or less for 2 hours or more.

The occurrence of cracks in the molded product produced by the RTM molding method is due to the large shrinkage stress of the resin when it is cured. The shrinkage during curing of the resin includes reaction shrinkage accompanying the reaction of the resin and heat shrinkage that occurs when the temperature is cooled from the molding temperature to room temperature. There is a contraction in a rubber state up to a glass transition temperature (Tg) and a contraction in a glass state called a glassy contraction from a glass transition temperature to room temperature. The matrix resin of the molded body produced by the RTM molding method is required to have a small stress generated by all of these curing shrinkages, that is, a curing shrinkage stress.

As a method for reducing the curing shrinkage stress of the above resin, it is effective to mix a high molecular weight polymer or an inorganic material in the resin composition. However, depending on the resin composition containing the high molecular polymer or the inorganic material, It cannot be of low viscosity. Therefore, in the RTM molding method using an epoxy resin as a matrix resin, it is possible to suppress the occurrence of cracks due to curing shrinkage of the resin by using an ordinary epoxy resin composition and devising various molding conditions. The current situation.

[0008]

Therefore, an object of the present invention is to stably maintain a low viscosity of 10 poise or less for a long time, and to reduce the shrinkage stress at the time of curing, and to prevent the cured molded article from cracking. It is an object of the present invention to provide an epoxy resin composition that is less likely to generate, and particularly to provide an epoxy resin composition that is suitable for use as a matrix resin for a molded product by the RTM molding method.

[0009]

The above object is achieved by the epoxy resin composition of the present invention having the following constitution. That is, according to the present invention, 100 parts by weight of a bisphenol type epoxy resin (A), 50 to 250 parts by weight of a bifunctional epoxy resin (B) having a naphthalene skeleton, and a particle size of 0.5 μm.
It is composed of 5 to 60 parts by weight of crosslinked rubber fine particles (C) of m or less and a curing agent (D), and has a viscosity of 10 poise or less.
The epoxy resin composition is characterized in that it can be held for a time or longer.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION In the above-mentioned epoxy resin composition of the present invention, the bisphenol type epoxy resin (A) is
The bisphenol epoxy resin may be a single bisphenol epoxy resin or a mixture of different kinds of bisphenol epoxy resins. The bisphenol epoxy resin (A) may be a bisphenol F epoxy resin having an epoxy equivalent of 200 or less. A bisphenol A type epoxy resin is preferable. These epoxy resins alone,
Alternatively, two or more may be mixed and used.

The epoxy resin (B) having a naphthalene skeleton has a naphthalene skeleton in its molecule.
A functional epoxy resin is used. As the bifunctional epoxy resin (B) having a naphthalene skeleton, a commercially available product, Epiclon HP-4032 "Dainippon Ink and Chemicals, Inc."
Co., Ltd. ”can be mentioned.

Bisphenol type epoxy resin (A) 10
When the amount of the epoxy resin (B) having the naphthalene skeleton is less than 50 parts by weight with respect to 0 parts by weight, a molded product having sufficient crack resistance and rigidity cannot be obtained, and when it exceeds 250 parts by weight. As a result, the toughness of the molded product is reduced. Therefore, the epoxy resin (B) having a naphthalene skeleton is a bisphenol type epoxy resin (A).
50 to 250 parts by weight, preferably 7 to 100 parts by weight
It is mixed in the range of 5 to 150 parts by weight.

The crosslinked rubber fine particles (C) having a particle size of 0.5 μm or less are not limited to the kind of rubber, and include, for example, acrylic rubber, silicone rubber, butyl rubber, NBR,
Crosslinked rubber fine particles such as SBR, IR and EPR can be used, and those having a particle size of 0.5 μm or less, preferably 0.3 μm or less are blended in order to avoid defective impregnation.

Bisphenol type epoxy resin (A) 10
When the amount of the crosslinked rubber fine particles (C) having a particle diameter of 0.5 μm or less is less than 5 parts by weight with respect to 0 parts by weight, the low stress effect of the resin composition becomes too small, and when it exceeds 60 parts by weight, The viscosity of the resin composition becomes too high and the impregnating property decreases. For this reason, the crosslinked rubber fine particles (C) having a particle diameter of 0.5 μm or less can be converted into the bisphenol type epoxy resin (A) 100.
5 to 60 parts by weight, preferably 10 to 5 parts by weight
It is compounded within the range of 0 parts by weight.

The crosslinked rubber fine particles (C) having a particle size of 0.5 μm or less are used as the bisphenol type epoxy resin (A), the epoxy resin (B) having a naphthalene skeleton, when the epoxy resin composition of the present invention is prepared. Alternatively, it may be blended in these mixed resins, but a commercially available resin composition obtained by previously blending bisphenol type epoxy resin (A) with crosslinked rubber fine particles (C) having a particle size of 0.5 μm or less, for example, BPA328 "Nippon Shokubai Co., Ltd.", BPF307
"Nippon Shokubai Co., Ltd.", BPA601 "Nippon Shokubai Co., Ltd."
Made ", cross-linked NBR modified epoxy resin" Nippon Synthetic Rubber "
Co., Ltd. ”or the like may be used.

The curing agent (D) is not particularly limited and, for example, amine type, acid anhydride type, phenol type, anionic polymerization catalyst type, cationic polymerization catalyst type and the like can be used.

The epoxy resin composition of the present invention comprises 100 parts by weight of the above bisphenol type epoxy resin (A) and 50 to 50 of the bifunctional epoxy resin (B) having a naphthalene skeleton.
It is composed of 250 parts by weight, 5 to 60 parts by weight of crosslinked rubber fine particles (C) having a particle diameter of 0.5 μm or less, and a curing agent (D), and can stably maintain a viscosity of 10 poise or less for 2 hours or more. It is possible to maintain the viscosity of 5 poise or less for 2 hours or more.

The criterion for determining whether or not the epoxy resin composition can be kept at a viscosity of 10 poise or less for 2 hours or more is to measure the isothermal viscosity of the epoxy resin composition for 2 hours by using a measuring device RDA manufactured by Rheometrics. -700, Dis
k Plate 25mmφ, Gap 0.5mm, R
ate 10 rad / sec.

[0019]

EXAMPLES The concrete constitution of the epoxy resin composition of the present invention will be explained below, and the characteristics of the epoxy resin composition will be explained in comparison with the characteristics of the epoxy resin composition of the comparative example.

The components used in the following examples and comparative examples are as follows. Ep828: Bisphenol A type epoxy resin "Yukaka Shell Co., Ltd." HP-4032: Bifunctional epoxy resin having a naphthalene skeleton "Dainippon Ink and Chemicals Co., Ltd." BPA328: Bisphenol type epoxy resin 100 parts by weight Particle size of 0. Epoxy resin composition in which 20 parts by weight of acrylic rubber fine particles, which are 3 μm cross-linked rubber fine particles, are dispersed and blended “Nippon Shokubai Co., Ltd.” BPF307: 100 parts by weight of bisphenol type epoxy resin. Epoxy resin composition in which 20 parts by weight of acrylic rubber fine particles, which are 3 μm crosslinked rubber fine particles, are dispersed and blended “Nippon Shokubai Co., Ltd.” DDS: diaminodiphenylsulfone MNA: methylnadic acid anhydride 2E4MZ: 4-ethyl- 2-Methylimidazole DCMU: Dichlorodimethylurea Dicy: Dicyandiamide Acrylic rubber: Crosslinked rubber fine particles having a particle size of 0.5 μm or less

[Examples 1 to 11] and [Comparative Examples 1 to 5] Epoxy resin compositions were prepared by blending the components shown in the predetermined column of Table 1. In addition, in Table 1, the weight part of each component in a compounding composition is described.

[0022]

[Table 1]

[Examples 12 to 19] Epoxy resin compositions were prepared by blending the components shown in the predetermined column of Table 2. In addition, in Table 2, the weight part of each component in a compounding composition is described.

[0024]

[Table 2]

With respect to the epoxy resin compositions prepared in the above Examples and Comparative Examples, various measurements shown in Tables 3 and 4,
An evaluation was performed. The results are collectively shown in Tables 3 and 4. The measuring method and evaluation were performed as follows.

[Measurement and Evaluation of Viscosity of Resin Composition] The isothermal viscosity of the epoxy resin composition for 2 hours was measured by using a measuring device RDA-700 manufactured by Rheometrics to determine the density of Disk Pla.
te 25mmφ, Gap 0.5mm, Rate 1
The viscosity is 10 when measured under the measurement condition of 0 rad / sec.
A composition which is kept at a temperature of not higher than poise for 2 hours and has a viscosity of not higher than 10 poise even after 2 hours is indicated by ○ in the viscosity stability column of Tables 3 and 4, and 10 poises Those that exceeded were also indicated by x in the viscosity stability column of Tables 3 and 4.

As a concrete example, it is assumed that when the resin having a certain composition is subjected to the isothermal viscosity measurement at the holding temperatures of 60 ° C., 80 ° C., 100 ° C. and 120 ° C., the results shown in the following table are obtained. With this resin composition, it was possible to maintain a viscosity of 10 poise or less for 2 hours or more at a temperature between 80 ° C and 100 ° C. The resin composition having such a temperature was marked with “◯”. Holding temperature Initial viscosity Viscosity after holding for 2 hours 60 ° C.> 10 poise Not measured 80 ° C. <10 poise <10 poise 100 ° C. <10 poise <10 poise 120 ° C. <10 poise> 10 poise

Further, it is assumed that when the same measurement is carried out for resins having different resin compositions, the results shown in the following table are obtained. In such a case, it is considered that both the initial viscosity at a temperature between 60 ° C. and 80 ° C. and the viscosity after being held for 2 hours become 10 poises or less. Therefore, during this period, the temperature is further subdivided and the same measurement is performed. . If, as a result, the above conditions are satisfied at a certain temperature, it is marked with a circle. Holding temperature Initial viscosity Viscosity after holding for 2 hours 60 ° C.> 10 poise Not measured 80 ° C. <10 poise> 10 poise 100 ° C. <10 poise> 10 poise 120 ° C. <10 poise> 10 poise Repeat the above operation. The resin composition in which the temperature at which the above condition was satisfied could not be found was marked with x.

[Measurement and Results of Tg] With the epoxy resin compositions of Examples and Comparative Examples, 60 mm (l) × 12 m
A sample molded body of m (w) × 2 mm (t) was cured and molded. The curing conditions for curing and molding are as follows: Examples 1 to 12, Example 1
5 to 19 and the epoxy resin compositions of Comparative Examples 1 to 5 are 120 ° C. × 1 hour + 150 ° C. × 1 hour + 180.
℃ × 2 hours + 200 ℃ × 3 hours, for the epoxy resin composition of Example 13, 120 ℃ × 1 hour + 150 ℃ ×
2 hours + 180 ° C. × 3 hours, for the epoxy resin composition of Example 14, 100 ° C. × 1 hour + 120 ° C. × 2 hours + 150 ° C. × 3 hours.

The curve of temperature-G 'of the obtained sample molded body was measured by a measuring device RDA-700 manufactured by Rheometrics.
5 ° C / STEP temperature rise, Rate 10rad
The glass transition temperature (Tg) is obtained by the intersection of the tangent line drawn to G ′ in the glass state region and the tangent line drawn to G ′ in the transition region where G ′ changes greatly ) Was asked. The results are shown in Tables 3 and 4.

[Bending strength, elastic modulus, elongation (three-point bending)]
Each sample molded body of 60 mm (l) x 8 mm (w) x 2 mm (t) obtained by molding the epoxy resin composition in the same manner as in the above Tg measurement was processed by Orientec Tensilon 3
L / D (= distance between fulcrums / thickness) by point bending test:
16, indenter tip radius: 3.2 mm, CROSS HEA
D SPEED: 2 mm / min. Bending strength, elastic modulus, and elongation were obtained from the load-CROSS HEAD transfer weight curve obtained by measuring under the measurement conditions of. The results are shown in Tables 3 and 4.

[Evaluation of Cross Section (Crack, Void) of FRP Cured Molded Product] 100 mm × 100 mm × 10 mm carbon fiber preform was loaded into a press die and heated to have a viscosity of 1
After impregnating the epoxy resin composition of each of the above examples with 0 poise, it was subjected to press formation of 5 kg / cm ² and then FRP.
A sample compact was obtained. As the carbon fiber preform, a three-dimensional woven fabric was used for the epoxy resin compositions of Examples 4 and 6, and a plain weave stitch material was used for the epoxy resin compositions of the other Examples and Comparative Examples.

The curing conditions for this FRP cured molded article are 120 ° C. × 1 hour + 15 for the epoxy resin compositions of Examples 1-12, Examples 15-19 and Comparative Examples 1-5.
0 ℃ × 1 hour + 180 ℃ × 2 hours + 200 ℃ × 3 hours,
120 ° C. for the epoxy resin composition of Example 13
× 1 hour + 150 ° C. × 2 hours + 180 ° C. × 3 hours, for the epoxy resin composition of Example 14, 100 ° C. × 1
Time + 120 ° C. × 2 hours + 150 ° C. × 3 hours.

The obtained FRP sample molded body was cut and polished, and its cross section was observed with a microscope to observe the state of occurrence of cracks and voids. The results are shown in Tables 3 and 4 by ∘ when no cracks or voids were generated, by Δ when slightly observed, and by x when slightly observed.

[0035]

[Table 3]

[0036]

[Table 4]

As described above, the physical properties of the cured resins prepared from the epoxy resin compositions of Examples 1 to 11 are good, and cracks and voids are not generated in the FRP molded articles using the fiber reinforced preform. There was no

On the other hand, cracks were observed in the FRP molded product of the epoxy resin composition of Comparative Example 1, and cracks were observed in the FRP molded product of the epoxy resin composition of Comparative Example 2. Some were observed. Furthermore, the epoxy resin composition of Comparative Example 3 had poor viscosity stability, and voids were generated in the FRP molded product made of the epoxy resin composition. Further, the cured molded article of the epoxy resin composition of Comparative Example 4 has extremely low bending strength and elastic modulus, the cured molded article of the epoxy resin composition of Comparative Example 5 has low elongation, and the FRP molded article has cracks. Was occurring.

The physical properties of the cured moldings made from the epoxy resin compositions of Examples 12 to 19 are as good as those of the epoxy resin compositions of Examples 1 to 11, and the carbon fiber reinforced by preform is used. No crack or void was generated in the FRP molded product.

[0040]

According to the epoxy resin composition of the present invention,
It can be molded into a cured molded product having excellent physical properties, and when used as a matrix resin for a fiber-reinforced composite material, it can be molded into an FRP molded product with extremely few cracks and voids during molding. .

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Masahiro Sugimori Inventor, Masahiro Sugimori 4-chome, Sunadabashi, Higashi-ku, Aichi Prefecture Mitsubishi Rayon Co., Ltd. Product Development Laboratory (72) Inventor Tetsuya Yamamoto 10 Oe-cho, Minato-ku, Nagoya-shi, Aichi Address Mitsubishi Heavy Industries, Ltd.Nagoya Aerospace Systems Works (72) Inventor Shigeru Nishiyama 10 Oemachi, Minato-ku, Nagoya, Aichi Prefecture Mitsubishi Heavy Industries Nagoya Aviation & Space Systems Works

Claims (1)

[Claims] 1. A bisphenol type epoxy resin (A) 1
00 parts by weight, 50 to 250 parts by weight of a bifunctional epoxy resin (B) having a naphthalene skeleton, 5 to 60 parts by weight of crosslinked rubber fine particles (C) having a particle diameter of 0.5 μm or less, and a curing agent (D), Moreover, an epoxy resin composition characterized by being able to maintain a viscosity of 10 poise or less for 2 hours or more.