JPH066624B2 - Epoxy resin curing agent - Google Patents

Description

TECHNICAL FIELD The present invention relates to an epoxy resin curing agent.

[Conventional technology]

Aromatic polyamines such as diaminodiphenylmethane are conventionally known as curing agents for heat-resistant epoxy resins (for example, Hiroshi Kakiuchi, "Epoxy Resins," published by Shokodo).

[Problems to be Solved by the Invention] However, the epoxy resin cured with these curing agents lacks impact resistance.

[Means for solving problems]

The present inventors have earnestly studied a curing agent that gives a cured product having the same heat resistance as that of the cured product cured with the above-mentioned curing agent and having significantly improved impact resistance, and as a result, arrived at the present invention.

That is, the present invention has the general formula [Wherein R is H or an alkyl group having 1 to 18 carbon atoms (however, H is 50 mol% or less of the total aniline skeleton), R ', R "
Is H, a phenyl group or an alkyl group having 1 to 4 carbon atoms, and R ′ and R ″ are optionally connected to each other to form 5 or 6
It may form a member ring. X is H, an alkyl group having 1 to 4 carbon atoms or an electron withdrawing group, and n is 0.1 to 5. ] An epoxy resin curing agent comprising a reaction product of an amine compound (A) represented by the above and an isocyanate group-containing urethane prepolymer (B).

In the general formula (1), the alkyl group having 1 to 18 carbon atoms represented by R is methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, tert-butyl group, 2-ethylhexyl group, lauryl group, Examples include stearyl group.
Of these, preferred are a methyl group and an ethyl group. There is no limitation to one kind of R which exists in plural,
Two or more kinds may be mixed. However, H in R
Is 50 mol% or less in the total aniline skeleton, preferably
It is 30 mol% or less. When the amount of the primary aniline skeleton in the case where R is H is larger than 50 mol%, the flexibility of the epoxy resin cured product decreases.

Examples of the alkyl group having 1 to 4 carbon atoms represented by R'and R "in the general formula (1) include methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group and isobutyl group. And R ″ may be the same or different. R'and R "are optionally linked to each other to form a divalent hydrocarbon group having 4 or 5 carbon atoms, such as (M is 4 or 5) and may form a 5- or 6-membered ring together with the carbon atom connecting the two aniline skeletons. Preferred among R'and R "are H, a methyl group and a phenyl group.

Examples of the alkyl group having 1 to 4 carbon atoms of X in the general formula (1) include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group and a tert-butyl group. Examples of the electron withdrawing group include halogen such as F, Cl and Br, nitro group, trifluoromethyl group and the like.
Preferred among X are H, methyl group, ethyl group and halogen. In the general formula (1), the plural Xs are not limited to one kind, and two or more kinds may be mixed.

In the general formula (1), n is preferably 1 to 4. n is
When it is less than 0.1, the heat resistance is lowered, and when n is more than 5, the heat resistance is improved but the impact resistance is deteriorated.

Specific examples of the amine compound (A) represented by the general formula (1) include an amine compound (A) in which each symbol in the general formula (1) is a symbol shown in Table-1.

The amine compound (A) can be produced by a known method, for example, having 1 to 18 carbon atoms.
It can be obtained by condensing a N-alkylaniline or a mixture of N-alkylaniline and a primary aniline with a ketone or an aldehyde under acidic conditions, but not limited to this method, after condensing the primary aniline with a ketone or an aldehyde, It may be N-alkylated, or the condensed aromatic hydrocarbon may be nitrated, then reduced and further N-alkylated.

The amine compound (A) in the present invention may be a single compound in which n is an integer, but from the viewpoint of compatibility with an epoxy resin, a mixture of various single compounds is preferable, and a compound in which n = 0 is 0 to 0 is preferable. 30%, n = 1 is 10-60%, n = 2 is 10-50
%, N = 3 to 5 is 0 to 40%, and n = 6 or more is about 0 to 30%. The amine compound (A) obtained by condensation of N-alkylaniline with ketone or aldehyde under acidic conditions is usually such a mixture.

Formaldehyde, acetaldehyde, etc. are used as aldehydes when producing the amine compound (A).
Examples of ketones include acetone, methyl ethyl ketone, methyl isobutyl ketone, acetophenone, and cyclohexanone. Of these, the preferred one is
Formaldehyde, acetaldehyde and acetone.

In the production of the amine compound (A), n can be calculated by the following formula, for example, when the compound (A) is produced from x mol of N-methylaniline and y mol of formaldehyde.

n = (2y−x) / (x−y) Using an amine of the general formula (1) and optionally an amine in which R is H in the general formula (1) is more than 50 mol% of the total aniline skeleton. Good.

In this case, in all the amine compounds, those in which R is H may be 50 mol% or less of the total aniline skeleton.

Examples of the isocyanate group-containing urethane prepolymer (B) include a prepolymer composed of a high molecular weight polyol and an excess of organic polyisocyanate.

Examples of the polymer polyol include polyether polyol, polyester polyol, and a mixture of two or more of these.

As polyether polyols, low molecular weight polyols (ethylene glycol, propylene glycol, 1,4
-, 1,3-Butanediol, 1,6-hexanediol, diethylene glycol, dipropylene glycol, cyclohexylene glycol, low molar ethylene oxide adduct of bisphenol A, bifunctional polyols such as N-methyldiethanolamine; glycerin, trimethylol Trifunctional or higher functional polyols such as propane, triethanolamine, pentaerythritol, sorbitol, sucrose etc.) and / or amines (amino alcohols such as monoethanolamine; aliphatic polyamines such as ethylenediamine, diethylenetriamine;
Alicyclic polyamines such as isophorone diamine; alkylene oxides of heterocyclic polyamines such as aminoethylpiperazine [Alkylene oxides having 2 to 4 carbon atoms, such as ethylene oxide, propylene oxide, butylene oxide, etc., or two or more thereof (random and / or Block)] Addition product, ring-opening polymer of alkylene oxide (ring-opening polymerization of tetrahydrofuran, polytetramethylene ether glycol by hydrolysis, etc.)
And so on. Of these, preferred are polyethylene ether polyol, polypropylene ether polyol and polytetramethylene ether polyol.

Low molecular weight polyols for polyester polyols and /
Alternatively, a condensed polyester polyol obtained by reacting a polyether polyol having a molecular weight of 1000 or less with a dicarboxylic acid, a polylactone polyol obtained by ring-opening polymerization of a lactone, and the like are included.

Examples of the low molecular weight polyol include ethylene glycol, diethylene glycol, propylene glycol, dipropylene glycol, trimethylolpropane, glycerin, 1,4-, 1,3-butanediol, neopentyl glycol, 1,6-hexanediol; cyclic group Low molecular weight diols having, for example, those described in JP-B-45-1474:
Bis (hydroxymethyl) cyclohexane, bis (hydroxyethyl) benzene, an ethylene oxide adduct of bisphenol A, and the like], and a mixture of two or more thereof.

Examples of the polyether polyol having a molecular weight of 1000 or less include polytetramethylene ether polyol, polypropylene ether polyol, polyethylene ether polyol, and a mixture of two or more thereof.

Dicarboxylic acids include aliphatic dicarboxylic acids (succinic acid,
Adipic acid, azelaic acid, sebacic acid, etc.), aromatic dicarboxylic acids (terephthalic acid, isophthalic acid, phthalic acid, etc.), and mixtures of two or more thereof.

Examples of the lactone include ε-caprolactone.

Polyester polyols can be prepared by a conventional method, for example, (1) a low molecular weight polyol and / or a polyether polyol having a molecular weight of 1000 or less, a dicarboxylic acid or an ester-forming derivative thereof (for example, an anhydride (maleic anhydride, phthalic anhydride, etc.) Ester (dimethyl terephthalate, etc.), halide, etc.], or a method of reacting (condensing) with an anhydride thereof and an alkylene oxide (eg ethylene oxide and / or propylene oxide), or (2) an initiator (low molecular weight polyol and / or Alternatively, it can be produced by a method in which a lactone is added to a polyether polyol having a molecular weight of 1000 or less. Preferred of these polyester polyols are polyalkylene adipates such as polyethylene adipate, polypropylene adipate, polyhexamethylene adipate, polyneopentyl adipate, polyethylene propylene adipate, polyethylene butylene adipate, polybutylene hexamethylene adipate, and poly-ε- It is a caprolactone polyol.

As the organic polyisocyanate, those which have been conventionally used for polyurethane production can be used. Such polyisocyanates include aromatic polyisocyanates having 6 to 20 carbon atoms (excluding carbons in the NCO group) and 2 carbon atoms.
To C18 aliphatic polyisocyanate, C4 to C15 alicyclic polyisocyanate, C8 to C15 araliphatic polyisocyanate and modified products of these polyisocyanates (urethane group, carpoimide group, allophanate group, urea) Group, biuret group, uretdione group, uretoimine group, isocyanurate group, oxazolidone group-containing modified product and the like). Specific examples of such polyisocyanates include those described in JP-A-53-42294, such as 1,3- and 1,4-phenylene diisocyanate, 2,4- and / or 2,6-tolylene diisocyanate ( TDI), diphenylmethane-2,4'-
And / or 4,4'-diisocyanate (MD
I), naphthylene-1,5-diisocyanate, aromatic polyisocyanates such as m- and p-isocyanatophenylsulfonyl isocyanate; ethylene diisocyanate, tetramethylene diisocyanate, hexamethylene diisocyanate, dodecamethylene diisocyanate, 2,2,4-trimethyl Fats such as hexane diisocyanate, lysine diisocyanate, 2,6-diisocyanate methyl caproate, bis (2-isocyanate ethyl) fumarate, bis (2-isocyanate ethyl) carbonate, 2-isocyanate ethyl-2,6-diisocyanate hexanoate Group polyisocyanates; isophorone diisocyanate, dicyclohexylmethane diisocyanate (hydrogenated MDI), cyclohexylene diisocyanate , Alicyclic polyisocyanates such as methyl cyclohexylene diisocyanate (hydrogenated TDI) and bis (2-isocyanate ethyl) 4-cyclohexene-1,2-dicarboxylate; araliphatic such as xylylene diisocyanate and diethylbenzene diisocyanate Polyisocyanate; modified MDI (urethane-modified MDI, carbodiimide-modified MDI, trihydrocarbyl phosphate-modified MDI, etc.), urethane-modified TDI, and other modified polyisocyanates, and mixtures of two or more thereof.

Among the organic polyisocyanates, preferred are aromatic polyisocyanates and alicyclic polyisocyanates.

In producing the prepolymer (B), the ratio of the organic polyisocyanate to the high molecular weight polyol is such that the equivalent ratio of NCO group: active hydrogen-containing group is usually 1: 1.25 to 2.5.

The prepolymer (B) can be produced by a usual method, for example, it is obtained by reacting an organic polyisocyanate with a high molecular weight polyol at usually 20 to 220 ° C, preferably 50 to 180 ° C.

Isocyanate group content (NCO%) of (B) is usually 0.6 to 8
%, Preferably 1.5 to 6.5%.

Amine compounds with an active hydrogen-containing group (A) (-NH _2, -NH etc.), the equivalent ratio of the isocyanate groups of the prepolymer (B) is usually 2: 1 to 20: 1, preferably 4: 1 to 20: It is 1.

The reaction product of the amine compound (A) and the prepolymer (B) can be easily produced by adding (B) to (A) at usually 0 to 100 ° C, preferably 20 to 50 ° C and reacting.

As described above, in order to react with (A) in excess,
The epoxy resin curing agent of the present invention may contain a free amine compound (A) in addition to the reaction product of the amine compound (A) and the prepolymer (B).

The hardening | curing agent of this invention can be used together with another epoxy resin hardening agent as needed. Other epoxy resin curing agents include aromatic amines (4,4'-diaminodiphenylsulfone, 4,4'-diaminodiphenylmethane, N, N'-dimethyl 4,4'-diaminodiphenylmethane, N, N'-
Diethyl-4,4'-diaminodiphenylmethane, N,
N'-dimethyl-3,3'-diaminodiphenylmethane), a phenol-based curing agent (bisphenols (bisphenol A, bisphenol F, bisphenol S, etc.), phenolic resins (novolac phenolic resin,
Novolac cresol resin), a polymer of vinylphenol (poly-P-vinylphenol, etc.)} and the like. In this case, the content of the reaction products of (A) and (B) in the total curing agent is usually 5% by weight or more, preferably 20% by weight or more.
If the content of the reactants (A) and (B) is less than 5% by weight, the effect of improving impact resistance is small.

The epoxy resin used in combination with the curing agent of the present invention may be an ordinary one, for example, (1) a phenol ether type epoxy resin (a condensate of bisphenols and epichlorohydrin, a condensate of novolak phenolic resin and epichlorohydrin). , (2) ether-based epoxy resin [condensation product of polyol, polyether polyol, etc. and epichlorohydrin], (3) ester-based epoxy resin [methacrylic acid glycidyl ester and ethylenic double bond monomer (acrylonitrile, etc.) Copolymer],
(4) glycidyl amine epoxy resin (condensation product of amines and epichlorohydrin) such as glycidyl type epoxy resin and cycloaliphatic epoxy resin, epoxidized polybutadiene, non-glycidyl type epoxy resin such as epoxidized soybean oil. To be For details of epoxy resin, see "Chemistry of basic synthetic resin (new edition)" (1975 edition).
Miwa Tadahiro, published by Gihodo, pages 371-392.
Preferred among the epoxy resins are phenol ether type epoxy resins and glycidyl amine type epoxy resins. These epoxy resins may be used alone or in combination of two or more.

The hardening | curing agent of this invention is 0.5-1.5 normally in active hydrogen equivalent with respect to 1 equivalent of epoxy resins, Preferably it mix | blends at the ratio of 0.8-1.2. If the active hydrogen equivalent ratio of the curing agent is less than 0.5 or greater than 1.5, the heat resistance, hardness, and impact resistance of the cured epoxy resin are unfavorable.

In using the curing agent of the present invention, a reactive diluent such as olein oxide, glycidyl methacrylate, styrene oxide, phenyl glycidyl ether may be added, if necessary. In addition, silica powder, aluminum powder,
Fillers such as mica, calcium carbonate, milled glass fiber glass hollow microspheres, phenol hollow microspheres, and epoxy hollow microspheres may be added.

The amount of these used is usually 0 to 15% by weight in the case of a reactive diluent, usually 0 to 70% by weight in the case of a filler, a reinforcing material and hybrid materials thereof, with respect to the mixture of the curing agent and the epoxy resin. Is.

When the curing agent of the present invention is used, the epoxy resin and the curing agent are usually mixed at 25 to 90 ° C, preferably 30 to 70 ° C, and then poured into a mold for use. Mixing and casting can be done by conventional methods.

After casting in the mold, it is usually cured at 50 to 200 ° C. for 0.1 to 5 hours, preferably at 80 to 150 ° C. for 0.5 to 2 hours, and then demolded.

The molded product obtained after demolding is usually after-cured at 60 to 180 ° C. for 0.3 to 100 hours, preferably 100 to 150 ° C. for 1 to 30 hours to produce a product.

〔Example〕

The present invention will be further described below with reference to examples, but the present invention is not limited thereto. In the examples, use examples and comparative examples, parts indicate parts by weight.

Compounds (A) I to III shown in Table 1 were used in Examples and Use Examples.

Example 1 Polypropylene ether diol (SANNIX PP-
2000, Sanyo Chemical Industry Co., Ltd., molecular weight 2000) 100 parts and 4,
From 25 parts of 4'-diphenylmethane diisocyanate,
A prepolymer was made. This prepolymer (NCO%
= 3.4%) 100 parts and compound (A) I (active hydrogen equivalent = 113)
When 47 parts were mixed, an exothermic reaction immediately occurred to obtain a liquid epoxy resin curing agent. The viscosity of this product is 50 ℃
Was 70 poise and the active hydrogen equivalent was 398.

Example 2 Poly-ε-caprolactone glycol (Plaxel L-
230AL, manufactured by Daicel Chemical Industries, Ltd., molecular weight 3000) 1
A prepolymer was prepared from 00 parts and 11.6 parts of 2,4- and 2,6-toluene diisocyanate. 100 parts of this prepolymer (NCO% = 2.5%) and compound (A) II (active hydrogen equivalent = 114) 50. When the parts were mixed, the viscosity increased with heat generation, and a highly viscous liquid epoxy resin curing agent was obtained. Its viscosity was 50 ° C., 480 poise, and active hydrogen equivalent was 374.

Example 3 Polytetramethylene ether diol (PTMG2000,
A prepolymer was prepared by reacting 100 parts of Sanyo Chemical Industries, Ltd., molecular weight 2000) with 22 parts of isophorone diisocyanate at 100 ° C. for 6 hours.

100 parts of this prepolymer (NCO% = 3.4%) and compound
When (A) II (active hydrogen equivalent = 127) (80 parts) was mixed, an exothermic reaction occurred and a liquid epoxy resin curing agent was obtained. Its viscosity was 50 ° C., 20 poise, and active hydrogen equivalent was 295.

Use Examples 1 to 3 and Comparative Use Examples 1 to 2 Using the curing agents of Examples 1 to 3, epoxy resins were mixed in the composition as shown in Table-2.

As shown in Table 2, the curing agent IV and the curing agent of the present invention were mixed in a weight ratio of 1: 2, and blended so that the equivalent ratio of the epoxy resin and the curing agent mixture was 1: 1. Was injected into the mold and heat-cured under the conditions of 120 ° C. × 1 hour + 150 ° C. × 3 hours to measure the physical properties of the sheet-like molded article.
The results are shown in Table-3.

EFFECT OF THE INVENTION The curing agent of the present invention is used for curing an epoxy resin, and the cured product thereof has excellent heat resistance and impact resistance.

Conventionally used aromatic amine-based curing agents such as 4,4'-diaminodiphenylmethane give a cured product having excellent heat resistance but poor impact resistance. However, by using the curing agent of the present invention as at least a part of the curing agent, it has heat resistance comparable to that of the above-mentioned curing agent and can significantly improve impact resistance.

Further, when the compound (A) alone is cured, it gives a cured product having good heat resistance and impact resistance, but when the curing agent of the present invention is used, the heat resistance does not decrease and the impact resistance is further improved. Give a cured product.

Because of the above effects, the curing agent of the present invention is used in combination with an epoxy resin for casting, resin molding, and other molding methods for applications requiring high mechanical physical properties such as automobiles and electric machines. It can be used and is useful.

Claims (3)

[Claims] 1. A general formula [Wherein R is H or an alkyl group having 1 to 18 carbon atoms (however, H is 50 mol% or less of the total aniline skeleton), R'and R "
Is H, a phenyl group or an alkyl group having 1 to 4 carbon atoms, and R ′ and R ″ are optionally connected to each other to form 5 or 6
It may form a member ring. X is H, an alkyl group having 1 to 4 carbon atoms or an electron withdrawing group, and n is 0.1 to 5. ] An epoxy resin curing agent comprising a reaction product of an amine compound (A) represented by the above and an isocyanate group-containing urethane prepolymer (B). 2. A curing agent according to claim 1, wherein (B) is a prepolymer from a high molecular weight polyol and an excess of organic polyisocyanate. 3. A high molecular weight polyol is polypropylene ether polyol, polyethylene ether polyol,
The curing agent according to claim 2, which is a polyol selected from the group consisting of polytetramethylene ether polyol, poly-ε-caprolactone polyol, and polyalkylene adipate.