JPS61103922A - Epoxy resin composition for use in composite material - Google Patents

Abstract

PURPOSE:To provide the titled composition of high toughness and tensile elongation in the direction perpendicular to fiber with small damage due to impact, comprising polyepoxide, p-diaminobenzoate curing agent and high-molecular weight dimer acid-based polyamide. CONSTITUTION:The objective composition comprising (A) a polyepoxide [e.g., 1,4-bis(2,3-epoxypropoxy) diphenyl ether] (B) a curing agent of formula I (R is residue of either 2-10C alkylene glycol or 5-14C alicylic diol) (e.g., neophetyl glycol p-diaminobenzoate) and (C) a high-molecular weight dimer acid-based polyamide (prepared from diamine and dicarboxylic acid consisting mainly of dimer acid derived from dimerization of unsaturated higher fatty acid). The R, i.e. the group in the formula I is pref. neopentyl glycol residue of formula II.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an epoxy resin composition for composite materials that has excellent toughness and tensile elongation in the direction perpendicular to the fibers.

[Prior Art] Composite materials made of reinforcing materials such as carbon fibers, glass fibers, and aromatic polyamide fibers and epoxy resins are used for premium sports applications such as golf shafts and fishing rods, taking advantage of their high specific strength and specific modulus. Widely used for structural materials such as aircraft. However, the performance of the epoxy resins used in these composite materials is insufficient for applications that require greater strength and toughness, and there is a strong desire for the emergence of epoxy resins with superior toughness.

Many techniques have been proposed for improving the toughness of epoxy resins. One method is to add rubber such as acrylonitrile-butadiene copolymer to epoxy resin, and then cure the epoxy resin to form a rubber phase as a dispersed phase, which prevents cracks and improves adhesive strength. (For example, Japanese Patent Laid-Open No. 57-21
450). Other methods include adding and mixing thermoplastic 'I7M resins such as polysulfone and polyacrylate to epoxy resins to control the propagation of cracks in cured resins, and using these resins to improve the toughness of carbon fiber reinforced composite materials. There are ways to improve it (for example, The[3ritis
h Polymer Journal, Vol.
15, March, 1983, P, 71
．． 28th 3aa+pe 5yiposiui
, 1983, P, 367, JP-A-58-1
34126). However, these methods are unsatisfactory in dramatically improving the toughness of composite materials, and furthermore, when these rubbers and thermoplastic resins are mixed, the viscosity of the epoxy resin becomes extremely high, making it difficult to manufacture or mold prepregs. There are problems such as poor impregnation with the reinforcing material, and homogeneous mixing of the epoxy resin and the modifier is often impossible unless a common solvent is used for both.

Modification of epoxy resins with various polyamide resins has also been studied since ancient times. discloses a structural adhesive composition composed of an epoxy resin, an alkenylphenol polymer, and copolymerized nylon or nylon 12, and JP-A-56-152832 discloses a structural adhesive composition composed of a solid epoxy resin, a solid resol type phenolic resin, and a linear polyamide resin. A powder epoxy resin composition for coating film is disclosed.Also, U.S. Pat.
, 986.539 and JP-A-58-53913 disclose a composition comprising a dimer acid polyamide and an epoxy resin, or a prepreg comprising this composition and reinforcing fibers.

The dimer acid polyamides used in these patents are
It has a substantially sufficient amount of terminal groups to be used as a curing agent for epoxy resins. The composition made of an epoxy resin and a polyamide resin exemplified above is unsatisfactory in terms of performance from the viewpoint of improving the toughness of a composite material, and its structure is also clearly different from the present invention.

Furthermore, compositions made of dimer acid-based polyamides and epoxy resins that are reactive with epoxy resins have a large increase in viscosity due to the reaction, making it difficult to produce homogeneous products during the resin mixing process or prepreg formation process with reinforcing materials. It is inconvenient to obtain it.

4,4'-diaminodiphenylsulfone is used as a curing agent for epoxy resins used in aircraft CFRP. “Epoxy resin compositions using this curing agent have a high modulus of elasticity and a high heat distortion temperature, resulting in CFR
P has excellent heat resistance, interlaminar shear strength, and compressive strength, but has low tensile elongation at break in the direction perpendicular to the fibers.

As a result, the tensile properties of laminates such as 0°/90'' and 0°/±45°/900 are low, and the excellent properties of carbon fibers are not fully utilized.

[Problems to be Solved by the Invention] One object of the present invention is to provide an epoxy resin composition for composite materials that has excellent toughness and tensile elongation at break in the direction perpendicular to the fibers. is an epoxy resin composition for composite materials that has excellent toughness and tensile elongation at break in the direction perpendicular to the fibers and provides a homogeneous product with appropriate viscosity in the manufacturing process of resin compositions and prepregs for composite materials. It's about providing things.

[Means for Solving the Problems] The present invention provides: “(1) An epoxy resin composition for composite materials comprising the following (A), (B) and (C) as essential components.

(A> Polyepoxide (B) General formula ■ (In the formula, R is an alkylene glycol having 2 to 10 carbon atoms,
Alternatively, it is a residue of an alicyclic diol having 5 to 14 carbon atoms. The residue is an alkylene glycol or an alicyclic diol from which the hydroxyl group has been removed. ) Curing agent (C) High molecular weight dimer acid polyamide (2)
An epoxy resin composition for composite materials in the above (1), wherein R in the general formula (1) of the component (B) is neobentyl glycol dipraminobenzoate of Hz -CH2-C-CH2-2Hs.

(3) An epoxy resin composition for composite materials in the above (1), wherein the component (C) is a polymeric m-dimer acid-based polyamide having a terminal group concentration of 5×10 −4 molar equivalents or less per 1 g of polyamide. ”.

Polyepoxides that can be used in the present invention are compounds that have on average more than one epoxy group in the molecule, and this epoxy group may be present as a terminal group or may be internal to the molecule. . The polyepoxide may be a saturated or unsaturated aliphatic, cycloaliphatic, aromatic or heterocyclic compound, and may also be a compound containing a halogen atom, a hydroxyl group, an ether group, etc., for example, bisphenol A. , glycidyl compounds of Fa and S, glycidyl compounds of cresol novolak or phenol novolak, glycidyl compounds of aromatic amines, and cycloaliphatic epoxy resins.

Specific examples of such polyepoxides include 1°4-bis(2,3-epoxypropoxy)benzene, 4.4'-
Bis(2,3-epoxypropoxy)diphenyl ether. .

Another example of a polyepoxide is a glycidyl compound of polyhydric phenol. Polyhydric phenols that can be used for this purpose include, for example, resorcinol, catechol, hydroquinone, 2,2-bis(4-hydroxyphenyl)propane (bisphenol A), 2,2-bis(4-hydroxyphenyl)butane, bis( 4-hydroxyphenyl)sulfone (bisphenol S), bis(4-hydroxyphenyl)methane, tris(4-hydroxyphenyl)methane, 3.9-bis(3-methoxy,4-hydroxyphenyl)-2,4,8 , 10-tetraoxaspiro(5,5)undecane, and 2,2-bis(4-hydroxytetrabromophenyl)propane as a halogen-containing phenol.

Another example of a polyepoxide is a glycidyl compound of a polyhydric alcohol. Examples of polyhydric alcohols that can be used for this purpose include glycerol, ethylene glycol, pentaerythritol, and 2,2-bis(4-hydroxycyclohexyl)propane.

Examples of polyepoxides with internal epoxy groups include 4
-(1,2-epoxyethyl)-1,2-epoxycyclohexane, bis(2,3-epoxycyclopentyl)
Ether, 3,4-epoxycyclohexylmethyl-(
Examples include 3,4-epoxy)cyclohexanecarbo, xylate, and the like.

Another example of a polyepoxide is a glycidyl compound of an aromatic amine. Aromatic amines that can be used for this purpose include diaminodiphenylmethane, metaxylylene diamine, m-7 minophenol, p-aminophenol, and the like.

Among these polyepoxides, diglycidyl ether of bisphenol A, glycidyl compounds of talesol novolak or phenol novolak, glycidyl compounds of diaminodiphenylmethane, and glycidyl compounds of aminophenol are preferably used.

The compound represented by the general formula (1) of the present invention can be obtained by a known method. For example, by reacting an alkylene gelcol having 2 to 10 carbon atoms or an alicyclic diol having 5 to 14 carbon atoms with p-nitropenzoyl chloride, and then reducing the product with hydrazine in the presence of a palladium catalyst. Obtainable. As the fullylene glycol having 2 to 10 carbon atoms, ethylene glycol, 1,2
-propanediol, 1.3-propanediol, 1.
2-butanediol, 1,4-butanediol, 2,3
-butanediol, 1,5-bentanediol, 2,4
-bentanediol, neopentyl glycol, 1.3
-dimethyl-1,3-propanediol, 1,5-hexanediol, 1゜6-hexanediol, 2-ethyl-2-methyl-1,3-propanediol, 2-methyl-2゜4-bentanediol, 1.7-hebutanediol, 2.2-diethyl-1,3-propanediol, 2
-methyl-2-propyl-1,3-propanediol,
2.2-diethyl-1,3-propanediol, 2-methyl-2-propyl-1,3-propanediol, 1,
Examples include linear or side chain alkylene glycols such as 8-octanediol, 2-ethyl-1,3-hexanediol, 1,9-nonanediol, and 1,10-decanediol. Alkylene glycols may contain heteroatoms such as oxygen, sulfur, etc.
Examples include diethylene glycol, triethylene glycol, thiogentanol, and the like. Carbon number 5-14
Examples of the alicyclic diol include 1,3-cyclobentanediol, 1,4-cyclohexanediol, '1.4-
Examples include diols such as cyclohexane dimethylol, 1,5-decane diol, and tricyclodecane dimethylol. Among these alkylene glycols and alicyclic diols, a cured epoxy resin having particularly excellent tensile properties can be obtained by using a linear or side chain alkylene glycol having 4 to 8 carbon atoms.

Theoretically, the amount of this compound to be added may be 1 equivalent of amine per 1 equivalent of epoxy. From the viewpoint of elongation, etc., the amount of this compound added is 0.5 to 1.5 equivalents, more preferably 0.8 to 1.2 equivalents, per equivalent of epoxy. Also,
In the present invention, it is of course possible to use this compound in combination with other curing agents. Furthermore, boron trifluoride, amine complexes, imidazole compounds, etc. can also be used as curing accelerators.

The high molecular weight dimer acid polyamide used in the present invention is a polyamide manufactured from dicarboxylic acid whose main component is dimer acid obtained by dimerizing unsaturated higher fatty acids and diamines such as ethylene diamine and hexamethylene diamine. be. The unsaturated higher fatty acids used are drying oils,
Obtained by polymerization of semi-drying oils or raw materials rich in these free acids or simple aliphatic alcohol esters of these acids, especially linoleic acid. The term "dimer acid" as used herein includes not only individual dimer acids but also mixtures of dimer acids.

Dimer acid mixtures are often predominantly trimers, but also include trimers, polymers, and monomers.

Various dimer acids can be used, but those obtained by polymerizing substances rich in linoleic acid or linoleic acid are readily available. As this high molecular weight dimer acid polyamide, for example, one obtained from a dimer of lylunic acid is sold under the trademark of Macromelt n (manufactured by Henkel Nippon Co., Ltd.).

The high molecular weight polyamide used in the present invention is approximately 10
A solid polyamide having a softening temperature in the range of 0 to 200°C, and in particular, one in which the total amount of terminal amino groups and terminal carboxyl groups is 5 x 10''5 molar equivalent or less per 1 g of polyamide is preferably used. It is particularly important that the polyamide used in the present invention has a sufficiently high molecular weight. Polyamides with low molecular weight, a large number of terminal groups, and high reactivity with epoxides have a small effect on improving the toughness of composite materials, and also During the mixing process and the process of impregnating reinforcing material to produce prepreg, the two react and the viscosity increases, making it difficult to produce high-quality prepreg. The amount of polyamide used is 5 to 100 parts by weight, preferably 10 to 30 parts by weight, based on 100 parts by weight of the total amount of polyepoxide and curing agent. When the amount of polyamide used is less than 5 parts by weight, the effect of improving the toughness of the composite material is small, while when it is more than 100 parts by weight, homogeneous mixing becomes difficult and the heat resistance of the resin is greatly reduced.

There is no particular restriction on the method of mixing the components of the present invention, and a preferred method can be selected as appropriate depending on the properties of each component and the mixing state or dispersion state of the target compound. (A) as an example of the mixing method.

There is a method of forming a homogeneous solution at a relatively low temperature using a solvent in which the components (B) and (C) are dissolved, and another method is of mixing each component at a relatively high temperature without using a solvent. There is. In the latter case, it is preferable to first melt the polyepoxide and polyamide at a high temperature, lower the temperature, and then mix the curing agent.

The epoxy resin composition of the present invention is preferably used as CFRP, and the carbon fibers used in this case include carbon fibers in any form such as tapes, sheets, mats, and textiles arranged in a certain direction. It can also be applied to Furthermore, all materials normally used as reinforcing materials for FRP, such as glass fiber, boron 1iA fiber, and aluminum 11aA strip, can be used.

[Function] In the present invention, by combining a polyepoxide, a high molecular weight dimer acid polyamide, and a curing agent represented by the general formula (■), a resin composition for composite materials with improved brittleness of the epoxy resin and excellent toughness is provided. be done.

Use of the curing agent of the present invention improves the heat resistance of the cured product, has excellent compatibility with high molecular weight dimer acid polyamide, and significantly improves the homogeneity of the epoxy resin composition. Moreover, this combination improves the toughness of the composite material without causing inhomogeneous or undesirable increases in viscosity during the step of blending each component and the step of impregnating the reinforcing material to produce a prepreg. Furthermore, this epoxy resin composition significantly improves the tensile elongation of the C. unidirectional laminate in the direction perpendicular to the fibers.

[Example] The present invention will be explained in further detail by the following example. The amounts of each component in the examples represent parts by weight, and the contents of the polyepoxide are as follows.

Epoxy A: bisphenol A diglycidyl ether,
Yuka Shell Epoxy Co., Ltd. Epicote 828° Epoxy B Nidiaminosifylmethane tetraglycidyl compound, Sumitomo Chemical Co., Ltd. ELM434° Epoxy C: Tetrabromobisphenol A diglycidyl ether, Dainippon Ink Co., Ltd. Eviclon 152° Epoxy DEN, N, O-triglycidyl meta-aminophenol, Sumitomo Chemical Co., Ltd. tJELM120゜Example 1 15 parts of epoxy A, 840 parts of epoxy, epoxy 030
030 parts of epoxy and dimer acid polyamide
38.5 parts of Macromelt'' 6238 (softening temperature 138°C, amount of end groups 1.7×10 −4 molar equivalents/g) was placed in a flask and heated to 150°C in an oil bath while stirring.

A clear viscous liquid was obtained after 3 hours. 53 parts of neopentyl glycol valadiamino benzoate was added to this solution and quickly and uniformly dissolved. After defoaming by reducing the pressure in the flask, the blended resin was poured into a mold and heated at 180℃ for 2 hours.
A transparent cured plate having a thickness of 211 mm was obtained by curing for a period of time.

The glass transition temperature of the cured product (using a differential calorimeter, 4
(measured at a heating rate of 0°C/min) was 172°C, using a Shimadzu Autograph 15-5000 at a crosshead speed of 2.
．． The tensile elongation at break measured at 5ffl1m/min is 1
It was 0.9%.

Similarly, cured plates were made from a mixture of epoxy A1 epoxy B1 epoxy C1 epoxy D and neopentyl glycol valadiaminopenzoate without adding polyamide. The glass transition temperature of this material was 197°C, and the tensile elongation at break was 6.0%.

From this example, it was revealed that a cured product with high elongation in which dimer acid polyamide was homogeneously mixed was obtained without significantly lowering the glass transition temperature of the cured product.

Example 2 In place of "Macromelt" 6238 in Example 1, 'Macromelt' 6224 (softening temperature 126°C, terminal group amount 2
．． A clear solution of polyepoxide and polyamide was obtained using 1.times.10@-4 mole equivalent ffi/g). Neopentyl glycol valadiaminobenzoate was added to this solution to obtain a uniformly dissolved resin composition.

Example 3 15 parts of epoxy A, 855 parts of epoxy, 030 epoxy
A resin composition was prepared in the same manner as in Example 1 using 66 parts of Macromelt 6238 and 53 parts of neopentyl glycol valadiaminobenzoate.

When this was cured at 180° C. for 2 hours, a transparent cured plate was obtained.

Similarly, opaque cured plates were obtained when diaminodiphenylsulfone was used in place of neopentyl glycol valadiaminobenzoate.

From this example, it was revealed that by using neopentyl glycol valadiaminobenzoate as a curing agent, the compatibility was improved, and that a uniform resin cured plate could be obtained even if macromeltopa was mixed with the mixture.

Example 4 A transparent solution was prepared by dissolving the resin composition of Example 1 in 450 parts of tricrene/ethanol/methyl ethyl ketone mixed layer* (1/1/2°5 ratio). A plain weave cloth using T300 manufactured by Torayka Co., Ltd. was coated and impregnated with resin gold m to a concentration of 41%. After air drying for one day, the solvent was removed by heat drying, and a homogeneous prepreg with tack and drape properties was obtained. 24 sheets of this prepreg were laminated and heated at 180℃ using an autoclave.
Cured for 2 hours at a pressure of 6h/a+F to a thickness of approx.
A composite material of ゜ was obtained. ′
Example 5 15 parts of epoxy A, 840 parts of epoxy, 030 epoxy
part, 030 parts of epoxy and 6238 parts of "Macromelt"
At 3°C, 6 parts were heated to 150°C to obtain a clear viscous liquid. This solution was cooled to 135° C., neopentyl glycol valadiaminobenzoate was added, and uniformly dispersed quickly.

Using this resin, a resin film is formed on silicone vapor, and this film is transferred to the unidirectionally aligned fibers of "Torayca" T700 by heating and pressing so that the W is 35%, and the tackiness and drape properties are improved. A homogeneous unidirectionally aligned blibleg was obtained. 24 sheets of this prepreg were laminated and heated in an autoclave at 180°C for 2 hours at a pressure of 61q/a.
A composite material having a thickness of about 4.5 mm was obtained. Using a weight with a tip R161ffl on this composite material,
A falling weight 11i1 energy of 80−·cn+/cm (sample thickness) was applied. The degree of damage caused by this impact test was measured using an ultrasonic deep damage imaging device M4 manufactured by Canon Holonics.
It was measured using 00B type. The damaged area is shown in Table 1.

A unidirectional alignment blipreg was produced in the same manner as described above, using "Toreca" T3OO instead of "Toreca" T700. 16 sheets of this prepreg were stacked and cured using an autoclave at 180° C. for 2 hours at a pressure of 6Ic+1/rd to obtain a unidirectional laminated material with a thickness of about 21111111. Using Shimadzu Autograph IS-5000,
The tensile elongation at break of the composite material in the direction perpendicular to the fibers was measured at a crosshead speed of 2.510111/min. The results are shown in Table 1.

Comparative Example 1 A composite material was prepared in the same manner as in Example 5 using a composition to which no polyamide was added, and an impact test and a tensile test in the direction perpendicular to the fibers were conducted.

The results are shown in Table 1.

Example 6 A composite material was prepared in the same manner as in Example 5, except that 45.9 parts of "Macromelt" 6238 30°6 parts in Example 5 was used, and an impact test was conducted. The results are shown in Table 1.

Example 7 “Trading card” T instead of “Trading card” T700 in Example 5
A unidirectionally aligned brev leg was produced using the same resin composition and method as in Example 5, except that 300 was used. 16 sheets of this prepreg were stacked and heated to 180℃ using an autoclave.
, cured for 2 hours at a pressure of 61/d to a thickness of approximately 21/d.
A unidirectionally laminated material of Qm was obtained. Shimadzu Autograph l5-5
000, the tensile elongation at break in the direction perpendicular to the fibers of the composite material was measured at a crosshead speed of 2.5 mm and 1 minute. The results are shown in Table 1.

Comparative Example 2 845 parts of epoxy, 040 parts of epoxy, 015 parts of epoxy
The tensile elongation at break in the am-perpendicular direction of the unidirectional laminate was measured in the same manner as in Example 7 using 38 parts of diaminodiphenylsulfone, and 13.8 parts of "Macromelt" 6238. The results are shown in Table 1.

[Effect of the invention] (1) Damage to composite materials due to impact is reduced.

(2) A resin composition with high heat resistance is provided.

(3) Prepreg with stable quality and excellent handling properties can be produced.

(4) A homogeneous resin composition and cured resin can be obtained.

(5) Can be molded using an autoclave without requiring special conditions.

(6) The tensile elongation at break in the direction perpendicular to the fibers of the unidirectional laminated material is improved, and a homogeneous multidirectional laminated material can be produced.

Claims (3)

[Claims] (1) An epoxy resin composition for composite materials containing the following (A), (B) and (C) as essential components. (A) Polyepoxide (B) General formula ▲ Numerical formula, chemical formula, table, etc. ▼ [1] (In the formula, R is an alkylene glycol having 2 to 10 carbon atoms,
Alternatively, it is a residue of an alicyclic diol having 5 to 14 carbon atoms. The residue is an alkylene glycol or an alicyclic diol from which the hydroxyl group has been removed. ) Curing agent (C) High molecular weight dimer acid polyamide (2) In claim 1, R in general formula [1] of component (B) is a ▲ mathematical formula, chemical formula, table, etc. ▼ [2] An epoxy for composite materials that is neopentyl glycol diparaminobenzoate. Resin composition. (3) An epoxy resin composition for composite materials in claim 1, wherein component (C) is a high molecular weight dimer acid polyamide having a terminal group concentration of 5 x 10^-^4 molar equivalents or less per 1 g of polyamide. thing.