JPH02199116A - Epoxy resin composition - Google Patents

Abstract

PURPOSE:To obtain an epoxy resin composition useful as an adhesive, a sealing agent or a coating material and can give a cured product having flexibility and elasticity by mixing an epoxy resin containing a specified epoxy compound with a curing agent. CONSTITUTION:0.5-50 pts.wt. curing agent (e.g. dicyandiamide) is added to 100 pts.wt. epoxy compound comprising 5-100 pts.wt. epoxy compound having an urethane bond and a structure of formula I (wherein Ar is an aromatic bivalent group; and R is H, a halogen atom, a 1-10C alkyl or a haloalkyl), e.g. a compound of formula II, and 95-0 pts.wt. epoxy resin (e.g. bisphenol A epoxy resin). Thus, an epoxy resin composition which can give a cured product having flexibility and elasticity can be obtained. When a latent curing agent such as dicyandiamide or an imidazole is used as the curing agent, a one-pack epoxy resin composition which can be stored for a long time and used extensively can be obtained. It can be used as an adhesive, a sealing agent, a coating material, a painting material or the like.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a one-component epoxy resin composition whose cured product has flexibility and elasticity and is useful as an adhesive, a sealant, or a coating material.

<Conventional technology> Conventional epoxy resins are hard and brittle, so when used as adhesives, they generally have low peel strength and are prone to cracking, so they cannot be widely used in structural materials, coating materials, etc.
Furthermore, when used in applications that require elasticity as well as flexibility, such as covering materials for concrete structures, cushioning materials, or botting materials for areas subject to internal stress, the adhesiveness of the wood is limited. This is difficult in some respects.

Flexible epoxy resins have been developed to compensate for these shortcomings. These are classified into those that use an epoxy resin that has a chemical structure that exhibits flexibility in its skeleton, and those that use a curing agent that has flexibility.

Epoxy resins having a chemical structure exhibiting flexibility in their skeleton include glycidyl ester type, polyoxyalkylene glycol type, bisphenol A propylene oxide addition type, urethane modified type, polybutadiene modified type, and the like. However, when these epoxy resins are used, the curing speed is extremely slow and there is a problem in terms of workability. Furthermore, since these cured products have plastic elongation, it is difficult to use them in the above-mentioned applications that require elasticity.

On the other hand, as a flexible curing agent, polyamide type (
There are various types of amines (condensates of dimer acids or aliphatic dibasic acids and polyamines), long-chain amines (polyether amines, aliphatic modified amines, etc.), liquid polybutadiene-modified amines, etc., but all of them are difficult to use in terms of compatibility, curing speed, and physical properties. It's problematic and difficult to use.

By solving these problems, we have developed a product with excellent balance of physical properties.
A urethane-modified epoxy resin composition (Japanese Patent Publication No. 62-53527) has been proposed as an epoxy resin composition with good compatibility and whose cured product is flexible and transparent.

This is a urethane-modified epoxy resin in which a glycidyl group is introduced via a urethane bond into a urethane prepolymer obtained by reacting a polyisocyanate with a polyether polyol or polyester polyol used as a urethane resin raw material, and the terminal is epoxidized. It is a two-part epoxy resin composition containing as a main component.

<Problems to be Solved by the Invention> The urethane-modified epoxy resin composition has excellent properties and is highly useful. However, the urethane-modified epoxy resin, which is the main component of this resin composition, cannot be cured by imidazoles or dicyandiamides, so a one-component epoxy resin composition containing this epoxy resin cannot be obtained. Application is hindered.

The present invention has been made in view of the above facts, and aims to provide an epoxy resin composition whose cured product has flexibility and elasticity and can be liquefied.

<Means for Solving the Problems> The present invention combines a urethane bond with the formula (1) % formula % (wherein Ar represents a compound having an aromatic ring, and R represents a hydrogen atom, a halogen atom, a carbon number of 1 An epoxy compound 100 consisting of 5 to 100 parts by weight of an epoxy compound (a) having the structure (indicating ~10 alkyl groups or halogenated alkyl groups) and 95 to 0 parts by weight of an epoxy resin other than (a) (b) Hardening agent (
c) 0.5 to 50 parts by weight of the epoxy resin composition.

The present invention will be explained in detail below.

The epoxy compound (a) used in the present invention has a urethane bond and a structure represented by the following formula (I) in its molecule.

-0-Ar-0-CH, -c CH2\1 (where Ar is a compound having an aromatic ring, R is a hydrogen atom, a halogen atom, an alkyl group having 1 to 10 carbon atoms, or The urethane bonding moiety in the molecule of the epoxy compound (a) (representing a halogenated alkyl group) and the moiety represented by the above formula (R) may each be present at one or more locations.

The epoxy compound (a) is preferably a urethane bond-containing compound (urethane prepolymer) having an isocyanate group at the terminal, which is obtained by reacting a polyhydroxyl compound with an excess polyisocyanate compound.
is synthesized by reacting a compound represented by the following formula (!).

HO-Ar-0-CHi -c CH2N2 (1 (wherein, Ar is a divalent compound having an aromatic ring, R is a hydrogen atom, a halogen atom, an alkyl group having 1 to 10 carbon atoms, or a halogenated alkyl group) Examples of the polyhydroxyl compound used in the synthesis of the epoxy compound (a) include various polyester polyols or polyether polyols used in the production of general urethane resins.

The polyester polyol referred to here refers to a condensate of a polyhydric alcohol and a polybasic carboxylic acid, a condensate of a hydroxycarboxylic acid and a polyhydric alcohol, etc. The polyhydric alcohol used in these is, for example, ethylene glycol. , propylene glycol, butanediol, diethylene glycol, glycerin, hexanetriol, trimethylolpropane, etc. Examples of polybasic carboxylic acids include adipic acid, geltaric acid, azelaic acid, fumaric acid, maleic acid, phthalic acid, and terephthalic acid. Examples include acid, dimer acid, pyromellitic acid, and the like.

Also useful as condensates of hydroxycarboxylic acids and polyhydric alcohols are castor oil, reaction products of castor oil and ethylene glycol, and reaction products of castor oil and propylene glycol.

Polyether polyol is a product obtained by addition polymerizing one or more alkylene oxides such as ethylene oxide, propylene oxide, butylene oxide, and tetrahydrofuran to a compound having two or more active hydrogens. Any known polyether polyol used in the production of urethane resins can be used. In this case, examples of compounds having two or more active hydrogens include the polyhydric alcohols and polybasic carboxylic acids mentioned above, amines such as ethylenediamine and hexamethylenediamine, ethanolamine, propatoolamine, etc. Examples include alkanolamines, polyhydric phenols such as resorcinol and bisphenol, and mustard oil.

The polyisocyanate compound used in the synthesis of the epoxy compound (a) is a compound having two or more isocyanate groups in the molecule, which is used in the production of a urethane prepolymer having an isocyanate group at the end.
Various materials used in the production of ordinary urethane resins can be used. For example, ethylene diisocyanate, pro and diisocyanate, tetramethylene diisocyanate, hexamethylene diisocyanate, 2,4-tolylene diisocyanate, 2,6-1 lylene diisocyanate, phenylene diisocyanate, xylene diisocyanate, diphenylmethane-4,4'-diisocyanate, naphthylene -1,5-diisocyanate, isophorone diisocyanate, 1-methyl-2,4-diisocyanatecyclohexane, 1-methyl-2,6-diisocyanatecyclohexane, dicyclohexylmethane diisocyanate, and the like.

The urethane prepolymer having isocyanate groups at the terminals obtained from the polyhydroxyl compound and the polyisocyanate compound can be synthesized by a general method.

The temperature in this synthesis reaction is generally 40 to 140°C, preferably 60 to 120°C.

At this time, the charging ratio of the polyhydroxyl compound and the polyisocyanate compound is the ratio of the hydroxyl group in the polyhydroxyl compound to the isocyanate group in the polyisocyanate compound (OH/NC0), which may be 1.0 or less. It is preferably 0.25 to 0.75, and more preferably 0.25 to 0.75.

At this time, in order to promote the reaction, known catalysts for urethane polymerization, such as organometallic compounds such as dibutyltin dilaurate, stannous octoate, and stannic octoate, triethylenediamine, triethylamine, 1.
It is also possible to use tertiary amine compounds such as 8-diazabicyclo[5,4,0]undecene-7.

The compound represented by the formula (n) used in the synthesis of the epoxy compound (a) is, for example, (1) an alkyl group having 1 to 10 carbon atoms or a halogenated alkyl group, where n is 0 to 4; Also, Y and 2 are
a hydrogen atom, a halogen atom, an alkyl group having 1 to 10 carbon atoms, or a halogenated alkyl group, Y and Z may be the same or different, and R is a hydrogen atom, a halogen atom, Examples include compounds that are one of alkyl groups having 1 to 10 carbon atoms or halogenated alkyl groups.

The compound represented by the above formula (Natsu) can be synthesized by a known method, but the compound represented by the following formula (III) where Ar is an atom
) The synthesis method will be explained using the compound shown in (1) as an example.

1L The compound [C] represented by the above formula (III) is preferably a 2,6- Dimethyl-4-hydroxymethylphenol [B] is further synthesized by epoxidation.

Note that the methylolation reaction and the epoxidation reaction are already known; for example, the methylolation reaction is described in Dai Organic Chemistry (published by Asakura Shoten), volume 23, page 250. Further, the epoxidation reaction is described on page 241 of the same book.

Specifically, the methylolation of compound [A]
A formaldehyde aqueous solution is added dropwise to the sodium hydroxide aqueous solution at 10 to 15°C, and then the reaction is allowed to proceed at room temperature for 5 hours. The reaction solution is neutralized with acetic acid, and the resulting precipitate is recrystallized from benzene. Epoxidation of compound [B] is carried out by dissolving compound [B] and an excess amount of epichlorohydrin in methanol, adding an aqueous sodium hydroxide solution dropwise, and stirring at room temperature for 90 minutes.
Allow time to react.

After reaction 17, excess epichlorohydrin is azeotropically removed with toluene, and by-produced common salt is separated. After washing the product with water, it is dried under reduced pressure.

The synthesis of the epoxy compound (a) from the urethane prepolymer and the compound represented by the formula (!■) is preferably carried out by reacting the compound represented by the formula (II) following the synthesis of the urethane prepolymer. It will be done.

At this time, the charged molar ratio of the urethane prepolymer and the compound represented by the formula (!■) is the ratio of the hydroxyl group in the compound represented by the formula (■) to the terminal isocyanate group in the urethane prepolymer (OH /NC0) is preferably 1.0 or more, and more preferably 1.0 to 1.2.

Further, at this time, in order to promote the reaction, it is also possible to use the known catalyst for urethane polymerization described above in the section of the synthesis reaction of the urethane prepolymer.

The epoxy resin (b) used in the present invention may be any epoxy resin other than the epoxy compound (a).

That is, epoxy resins include widely used glycidyl ether epoxy resins such as bisphenol A epoxy resin, bisphenol F epoxy resin, novolac epoxy resin, and brominated epoxy resin, as well as cycloaliphatic epoxy resins and glycidyl epoxy resins. There are special epoxy resins such as ester-based epoxy resins, glycidylamine-based epoxy resins, and heterocyclic epoxy resins, and any of these can be used in the present invention.

Preferably, a liquid epoxy resin having an epoxy equivalent of about 160 to 220 is used.

The curing agent (C) used in the present invention may be one that is generally used as a curing agent for epoxy resins, that is, amines such as diethylenetriamine, isophorone diamine, m-xylylene diamine, and m-fuylene diamine. ,
Acid anhydrides such as trimellitic anhydride, polyamide resins produced by condensation of dimer acid and polyamines, imidazoles such as 2-ethyl-4-methylimidazole and 1-dodecyl-2-methyl-3-benzylimidazolium chloride. , dicyandiamide and its derivatives, BFl
, PFs, Am, Fs, 5bFs, and other Lewis acid amine complexes can be used. Of these,
Some imidazole compounds such as l-dodecyl-2-methyl-3-benzylimidazolium chloride, dicyandiamide and its derivatives, BF3, PF5
It is preferable to use a so-called latent curing agent such as an amine complex of a Lewis acid such as AsF5.5bFs, since it is possible to obtain a -wave type epoxy resin composition.

The epoxy compound (a), epoxy resin (b) and curing agent (e) described above may be used alone or in combination of two or more.

The epoxy resin composition of the present invention contains the above-mentioned epoxy compound (a), epoxy resin (b), and curing agent (C), and the content ratios thereof are as follows.

When the total amount of the epoxy compound (a) and the epoxy resin (b) is 100 parts by weight, the epoxy compound (a) is used in an amount of 5 to 100 parts by weight, preferably 50 to 100 parts by weight.

If the epoxy compound (a) is less than 5 parts by weight, the cured product of the resin composition of the present invention will have insufficient flexibility and become brittle.

The curing agent (C) is 0.5 to 50 parts by weight when the total amount of the epoxy compound (a) and the epoxy resin (b) is 100 parts by weight.
Parts by weight, preferably, when using amines, acid anhydrides or polyamide resins as the curing agent, the epoxy groups of the epoxy compound (a) and the epoxy resin (b) and the curing agent (
0.5 to 1.517) ffi (active group/epoxy group), and when using a so-called curing catalyst such as imidazole, dicyandiamide and its derivatives, or Lewis acid amine complex as a curing agent, O, S ~20 parts by weight is used.

Within the range specified in the present invention, the curing rate will be appropriate. Moreover, in the case of a - wave type, it is preferable also from a viewpoint of storage stability.

The resin composition of the present invention may contain various additives, such as diluents such as various monoepoxides, fillers such as silica and calcium carbonate, and colorants such as pigments, as necessary, to the extent that the gist of the present invention is not impaired. Agents may also be added.

<Example> The present invention will be explained in more detail below by giving examples and comparative examples.

[Example 1] Polytetramethylene glycol (PTMG- manufactured by Mitsubishi Chemical Industries, Ltd.) was placed in a 500 mA four-loop flask equipped with a thermometer, a nitrogen gas inlet tube, a calcium chloride tube, and a stirring device.
850, number average molecular weight 851, hydroxyl value 131.8) 1
27g was charged, and 53g of tolylene diisocyanate (TDI-80 manufactured by MD Kasei Co., Ltd.) was added at room temperature under a nitrogen stream.
The mixture was stirred at 80°C for 5 hours. 1 hour after addition of TDr-80, dibutyltin dilaurate (manufactured by Tokyo Kasei Kogyo Co., Ltd.) 0
．． 02g was added.

The urethane bond-containing compound synthesized in this way is given the formula (
65 g of the compound represented by III) was added, and the mixture was stirred at 80° C. for 4 hours until the isocyanate groups were completely blocked.

2.1 parts by weight of dicyanamide as a curing agent (C) was blended with 100 parts by weight of the epoxy compound (a) synthesized in this way to obtain an epoxy resin composition.

This epoxy resin composition was stored at room temperature and its storage stability was evaluated.

Further, this epoxy resin composition was cured at 160° C. for 13 hours, and its physical properties were evaluated by the following method.

The results are shown in Table 1.

(Method for evaluating physical properties) ■Tensile strength Using JIS No. 3 dumbbells, JIS K 6301 (
(1975), the force at break was measured.

■Tensile elongation Using JIS No. 3 dumbbells, JIS 8301 (
(1975), and the elongation at break was expressed in %.

(2) Tear Strength Using a Type B test piece, the strength at tear breakage was measured according to JIS 6301 (1975).

[Example 2] Polytetramethylene glycol (PT manufactured by Mitsubishi Chemical Industries, Ltd.)
MG-2000, number average molecular weight 1986, hydroxyl value 56
．． 5) 300g, tolylene diisocyanate 54g1
68 g of the compound represented by formula (III) was reacted in the same manner as in Example 1 to obtain epoxy compound (a).

1.3 parts by weight of dicyandiamide as a curing agent (C) was blended with 100 parts by weight of the epoxy compound (a) synthesized in this way to obtain an epoxy resin composition.

This epoxy resin composition was stored at room temperature and its storage stability was evaluated.

Further, this epoxy resin composition was cured under the same conditions as in Example 1, and its physical properties were evaluated in the same manner as in Example 1.

The results are shown in Table 1.

[Example 3] Epoxy compound (a) synthesized in the same manner as Example 1 100
1.2 parts by weight of 2-ethyl-4-methylimidazole, which is a curing agent (e), was added to the parts by weight to obtain an epoxy resin composition.

This epoxy resin composition was stored at room temperature and its storage stability was evaluated. In addition, this epoxy resin composition was heated at 80°C.
After curing for 6 hours, the physical properties were evaluated in the same manner as in Example 1.

The results are shown in Table 1.

[Example 4] Epoxy compound (a) synthesized in the same manner as Example 2 100
0.7 parts by weight of 2-ethyl-4-methylimidazole, which is a curing agent (0), was added to the parts by weight to obtain an epoxy resin composition.

This epoxy resin composition was stored at room temperature and its storage stability was evaluated.

Further, this epoxy resin composition was cured under the same conditions as in Example 3, and its physical properties were evaluated in the same manner as in Example 1.

The results are shown in Table 1.

[Example 5] Epoxy compound (a) 10 synthesized in the same manner as Example g41
Bisphenol A type liquid epoxy resin (ELA12B manufactured by Sumima Kagaku Kogyo Co., Ltd.), which is the epoxy resin (b), is added to 0 parts by weight.
, 10 parts by weight of epoxy equivalent (189) and 2.6 parts by weight of dicyandiamide as curing agent (e) were blended to obtain an epoxy resin composition.

This epoxy resin composition was stored at room temperature and its storage stability was evaluated.

Further, this epoxy resin composition was cured at 160° C. for 2 hours, and its physical properties were evaluated in the same manner as in Example 1.

The results are shown in Table 1.

[Example 6] Epoxy compound (a) synthesized in the same manner as Example 2
o parts by weight, epoxy resin (b) ELA-128
10 parts by weight and 1. dicyandiamide as curing agent (C).
8! i parts were blended to obtain an epoxy resin composition.

This epoxy resin composition was stored at room temperature and its storage stability was evaluated.

Further, this epoxy resin composition was cured under the same conditions as in Example 5, and its physical properties were evaluated in the same manner as in Example 1.

The results are shown in Table 1.

[Example 7] Epoxy compound (a) 1oo synthesized in the same manner as Example 2
Isophorone diamine 3, which is a curing agent (C), is added to the weight part.
Parts by weight were blended to obtain an epoxy resin composition.

This epoxy resin composition has poor storage stability and must be used as a two-part type.

Further, this epoxy resin composition was cured at 120° C. for 3 hours, and its physical properties were evaluated in the same manner as in Example 1.

The results are shown in Table 1.

Table 2 [Comparative Example 1] Polytetramethylene glycol (PTMG-850) 1
50g, tolylene diisocyanate 63g 1 formula (1
In place of the compound shown in Example 0), 28 g of glycidol was reacted in the same manner as in Example 1 to obtain a urethane-modified epoxy compound.

Urethane-modified epoxy compound 10 synthesized in this way
2.6 parts by weight of dicyandiamide having a cure of 111J (c) was added to parts by weight of 01i to obtain an epoxy resin composition.

This epoxy resin composition was heated to 160°C for 30 minutes for curing.
It took a while, but it didn't harden.

[Comparative Example 2] 2-ethyl-4-, which is a curing agent (c), was added to 100 parts by weight of a urethane-modified epoxy compound synthesized in the same manner as in Comparative Example 1.
1.4 parts by weight of methylimidazole was blended to obtain an epoxy resin composition.

This epoxy resin composition was kept at 80° C. for 6 hours for curing, but did not cure.

<Effects of the Invention> According to the present invention, an epoxy resin composition whose cured product has flexibility and elasticity can be obtained.

The epoxy resin composition of the present invention has a wide range of applications because it becomes a one-component epoxy resin composition that can be stored for a long time when a latent curing agent such as dicyandiamide or imidazole is used as a curing agent.

The epoxy resin composition of the present invention is highly useful when applied to adhesives, sealants, coating materials, paints, and the like.

Claims (1)

[Claims] (1) Urethane bond and formula (I) ▲Mathematical formulas, chemical formulas, tables, etc.▼(I) (In the formula, Ar represents a divalent compound having an aromatic ring, R represents a hydrogen atom, a halogen atom, and a carbon number of 1 ~10 alkyl groups or halogenated alkyl groups) 5 to 100 parts by weight of an epoxy compound (a) having the following structure, and 95 parts by weight of an epoxy resin other than (a) (b)
An epoxy resin composition comprising 0.5 to 50 parts by weight of a curing agent (c) per 100 parts by weight of an epoxy compound comprising 0 parts by weight.