JPS6058419A - Epoxy resin composition for carbon fiber reinforcement - Google Patents

Abstract

PURPOSE:To provide the titled composition having improved impact resistance without lowering the heat-resistance, water-resistance and mechanical characteristics of the original resin composition, and suitable as a structural material of aircraft, by adding a butadiene acrylonitrile rubber and anhydrous silica gel to an opoxy resin. CONSTITUTION:The objective composition is produced by compounding 100pts. wt. of an epoxy resin composition containing tetraglycidyl diaminodiphenylmethane of formula and diaminodiphenylsulfone with (A) preferably 1.5-4pts.wt. of a butadiene acrylonitrile rubber [preferably a carboxyl-containing butadiene acrylonitrile rubber having bonded acrylonitrile content of 15-55% and a Mooney viscosity (ML1+4, 100 deg.C) of 35-80] and (B) preferably 2.5-7pts.wt. of anhydrous silica gel (preferably fine powder having an average primary particle diameter of <=20mmu and a BET surface area of >=100m<2>/g).

Description

Detailed Description of the Invention The present invention provides a carbon fiber composite material (hereinafter abbreviated as CjRP) that has poor impact resistance, good heat resistance, and water resistance.
1j relates to an epoxy resin composition for producing. More specifically, an epoxy resin composition suitable as a prepreg resin for manufacturing CFRP which has high mechanical properties necessary as a structural material and has excellent heat resistance, water resistance, and high impact performance. relating to things.

CFRP is widely used as premium sporting goods due to its excellent specific strength and modulus of elasticity, but in recent years it has also begun to be used as a material for aviation, space equipment, automobiles, etc. However, CFRP has higher ILT resistance than metal materials. In order to expand the number of parts that can be used as structural materials, it is essential to improve impact performance. In particular, aviation fffi i'J automobiles are subject to various impacts during the manufacturing process and operation, so if these major parts are to be converted to CF RP, it is essential to improve their impact performance. -It is said that C is.

By the way, CFRP, which is currently used as a structural material for aircraft etc., requires heat resistance performance in addition to mechanical properties.
High performance epoxy resins are generally used as matrix resins. However, such epoxy resins, specifically tetraglycidyldiaminodiphenylmethane (hereinafter F
JCF RP lfi i"- However, it has the drawbacks of low elongation of the resin, lack of flexibility, and poor impact performance.Therefore, T G D D M
Attempts have been made to add liquid rubber such as Tolycar CTBN to DDS. However, although this method improves the impact performance to some extent, the compressive strength, heat resistance, and water resistance are significantly reduced, and it is not possible to provide the necessary characteristics for 4F5 afforestation for aircraft, etc. Therefore, there is a strong demand for a 10,000-stroke performance without reducing the heat resistance, water resistance, and mechanical properties of CFRI.

Therefore, the present inventors determined that T' G D D M / D
As a result of extensive research into improving the impact strength t1 of an epoxy resin composition with D S set to 0, the present invention was arrived at.

'4〕l, Ding G l) D Epoxy 91 trin containing M and DDS; iIl to 1f/J,
By adding butadiene/acrylonitrile rubber, water, silica, silica gel, 'r G l) D
lvl/DDS heat resistance, water resistance and mechanical 'F'
(It was possible to improve the impact performance without changing i to Fl).

Here, 1° GDDM used in the present invention is a tetrafunctional epoxy resin represented by the general formula, and a commercially available product is Q tba -Get (lV?l'' MY 720. from IJ (UK)). 11 E L manufactured by Yukagaku Kogyo Co., Ltd.
Examples include M434 and YH-434 manufactured by Tobu Kasei Co., Ltd. 10DDM has good adhesion to carbon fibers, and since it is a multifunctional epoxy resin, it can be hardened with a hardening agent (
[) When DS is used, the crosslinking density of the cured product increases, resulting in a cured product with good heat resistance and high elastic modulus.

Therefore, CFRP using TGDDM/DDS as a matrix resin has excellent mechanical properties and heat resistance, but on the other hand, the flexibility of the resin is poor, so the impact resistance is inferior. Therefore, the CFRP used for aircraft is generally used as an epoxy resin.
Generally, epoxy resins such as epoxy resins are added, and in the present invention, there is no problem even if other epoxy resins are contained in addition to TGDDM. However, with this method, CFRP
It is possible to improve some of the mechanical properties of the material, but impact performance cannot be improved. Therefore, conventionally l-lycarc T
Attempts have been made to add liquid rubber such as BN, but although this method improves impact performance to some extent,
Compressive strength and heat resistance 1b water resistance were significantly reduced, and satisfactory results could not be obtained. Therefore, *the inventors
/The decrease in heat resistance and compressive strength when liquid rubber is added to DDS will affect the glass transition temperature and elastic modulus of the cured resin.
(As a result of intensive research based on this knowledge, we arrived at Invention A) However, from the viewpoint of compressive strength of CF Rl'', it is not allowed to lower the elastic modulus of 71-Rix resin. It has been found that it is effective to suppress the decrease in the elastic modulus of the entire matrix by doing so, and to also use a method of increasing the elastic modulus of the cured resin product by adding an inorganic filler to 71-Rix.

For the purpose of the present invention, butadiene-acrylonitrile rubber, which is solid at room temperature, is effective as the rubber component, and anhydrous silica gel is effective as the inorganic filler. More specifically, the butadiene-acrylonitrile rubber has a bound acrylonitrile content in the range of 15 to 55%, and has a Mooney viscosity (MLI + 4.100°C).
Butadiene-acrylonitrile rubber containing a carboxyl group in the range of 35 to 80 is preferred, and commercially available products include N1po11031 and N1 manufactured by Nippon Zeon Co., Ltd.
N1p0 such as p0+1072, N1polDN211
There is 1 ~ lil rubber in. The rubber component is preferably added in an amount of 0.5 to 5,000 m parts, more preferably 1.5 to 4.0 mm parts, per 100 m parts of the EVO4 resin composition. If the addition m is less than 0.5 mfIi711, the impact performance will not be improved; If it exceeds 1 m of Ofl, the compressive strength and heat resistance will drop significantly, which is not preferable. Next, the anhydrous silica gel used in the present invention has finer particles, and the average diameter of the primary particles is 20111μ or less,
The surface area by BET method is 100rn'/! Fine particles of I or more are preferable. Commercial products of such anhydrous silica gel include various grades such as Aerosil 200, Aerosil 300, and Aerosil 380 manufactured by Nippon Aerosil ((2)).

The addition m of anhydrous silica gel according to the present invention is resin composition 10.
The amount is in the range of 2.0 to io, o parts by weight, more preferably 2.5 to 7.0 parts by weight per 0 small ω parts. /Work 1" When the addition ω of gill is less than 2.0 parts by weight, the compressive strength is 1. There is no improvement. On the other hand, if each addition exceeds 10.0%, the viscosity of the resin becomes too high and the resin is not sufficiently impregnated into the carbon fibers during molding, resulting in a decrease in compressive strength.

In addition, when using the resin composition of the present invention as a prepreg resin composition, etc., the resin mixture may be preliminarily treated with a small amount of aromatic diamine before adding DDS for the purpose of adjusting the viscosity as necessary. There is no problem even if prepolymerization is performed. Furthermore, in carrying out the present invention, other aI fibers such as glass fibers and organic fibers may be mixed and used in addition to carbon fibers as a reinforcing material.

Further, the form of the reinforcing material may be one-sided prepreg or cross prepreg. Furthermore, the carbon fibers used may be polyacrylonitrile-based, pitch-based, rayon-based, or other carbon fibers.

Characteristic evaluation of CFRP was performed by the following method.

(+)! Residual compressive strength after 7 shots 36 sheets of prepreg using Patreca cloth #6343 (Toshishiki Co., Ltd.) were laminated, cured in an autoclave, and then cut into pieces with a width of IQ cm and a length of 150111, and the end faces were A test piece was prepared by thoroughly polishing it.A weight was dropped onto the center of the test piece to apply an impact energy of 500 in-lb/in, and the compressive strength of the test piece was measured.

(2) Compressive strength A unidirectional prepreg was created using Toshishiku Co., Ltd.'s "Trading Card" T300, and the thickness of the molded product was 2.
Stack the required number of sheets so that the angle is 110112 degrees and
-1~ After molding in crepe, measurements were made in accordance with ASTM D695.

(3) Heat resistance and water resistance A test piece was immersed in hot water at 72°C for 14 days and subjected to water absorption treatment, and then the compressive strength was measured at 93°C, and the compressive strength was measured at room temperature for a test piece that had not been subjected to water absorption treatment. compared with compressive strength.

The contents of the present invention will be explained in more detail in the following Examples.

Example 1 ELM434 manufactured by Shiyu Kagaku Kogyo Co., Ltd.
1j1 Hishiel] Niboxi Co., Ltd. Ep154, El)
15 overlapping parts and 10 parts by weight of each of 82ε3<)I
After C-coating, the resin composition prepared by adding 40 (fq m parts) of 4,4'-diaminodiphenylsulnotone was
Composition <A). Next, composition (A) 100!1'!
1 part by weight, 5 parts by weight of Aerosil 380, and 1 part by weight of N1po.
11072 was added to form a resin composition (1
3), and 3 small parts of N 1poll O72 were added to 100 parts by weight of the coarse composition (A) to prepare a resin composition (C).

Example 2 Compositions (A), (B), and (C) obtained in Example 1
) was dissolved in methyl ethyl ketone, and Toshiku Co., Ltd.) was dissolved in methyl ethyl ketone.
120 after impregnated with manufactured trading card cloth #6343
Cross prepregs were made by drying at °C. Thirty-six sheets of the obtained prepreg were laminated, pressurized to 7 kq/DTF in an autoclave, and cured at 180° C. for 2 hours to create a molded product. The volume content of carbon fibers in the obtained molded products was 57 to 58%, which was almost the same value for all resin compositions.

A test piece with a width of 1Qcm and a length of 15cm was cut out from the molded product obtained, and after polishing the end surface, a weight was dropped into the medium heat part of the test piece.
After applying an impact energy of 1 b/in, the compressive strength of the test piece was measured, and the impact performance was compared using the residual compressive strength after impact as J:. For comparison, the compressive strength of a test piece without impact was also measured. Table 1 shows the result 41 obtained by 1η. As is clear from Table 1, the effects of the present invention are clearly observed.

Example 3 Compositions (A), (B) and (
Using C), "Trading Card" T-300 manufactured by Toshishiki Co., Ltd. was aligned in one direction, and then the resin composition was heated and melted to avoid impregnation to create a unidirectional pre-reg. A molded article was produced in the same manner as in Example 2 by laminating 14 sheets of the obtained prepreg in one layer. (!7) The volume content of carbon fiber in the molded product was in the range of 62 to 63% for all compositions, and was almost the same. After cutting to 80 nv, the tabs were glued together and the compressive strength was measured in accordance with ASTM-D695.
The compressive strength of the untreated specimen was measured at 93°C after being immersed for 4 hours at air temperature. The heat resistance and water resistance were evaluated by comparing with the established values. The results obtained are shown in Table 1. As is clear from Table 1, the effects of the present invention are clearly recognized.

Table 1

Claims (1)

[Claims] (1) De 1 - An epoxy resin composition containing laglycidyl diaminodiphenylmethane and diaminodiphenyl sulfone, etc., containing at least A, butadiene-acrylonitrile rubber, and B, anhydrous silica gel, etc. Epoxy resin composition for fiber reinforcement.