JPH09227658A - Curing agent for water-based epoxy resin - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a curing agent which has good water dispersibility and can give water-based epoxy resins giving cured coating films excellent in anticorrosiveness by using a product prepared by modifying a specified polyamine compound by an addition reaction with a specified polyglycidyl ether compound as the effective component. SOLUTION: This agent is prepared by modifying a polyamine compound (A) represented by formula I (wherein A is a residue derived by removing mx hydroxyl groups from a di- to hexa-valent polyol; R1 is a 2-4C alkylene; R2 is a 1-4C alkylene; (m) is 2-6; and (n) is 1-30, provided that at least 60% of R1 s are 1,2-propylene groups) by an addition reaction with a polyglycidyl ether compound (B) represented by formula II (wherein B is a residue derived by removing qx hydroxyl groups from a di- to tetra-valent polyol or polyphenol; R1 is a 2-4C alkylene; (q) is 2-4; and (p) is 1-50, provided at least 60% of R1 s are 1,2-propylene groups) in such a ratio that 0.01-0.4 epoxy group of compound B is present per aminic active hydrogen of compound A.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a curing agent used for curing an aqueous epoxy resin containing water as a medium, and more specifically, a polyamine compound containing an oxypropylene chain and a polyglycidyl containing an oxypropylene chain. The present invention relates to a curing agent for an aqueous epoxy resin, which contains a modified product added and modified with an ether compound as an active ingredient.

[0002]

2. Description of the Related Art Epoxy resin compositions containing an epoxy resin and a curing agent have many excellent properties such as adhesion to various substrates, heat resistance, chemical resistance, electrical properties and mechanical properties. Has a wide industrial field,
In particular, it is used in the field of paints and adhesives.

When used for these purposes, conventionally, solvent type ones using various organic solvents have been generally used. However, there is a risk of fire, harmfulness to human body, and cost increase due to use of the solvent. Not only the problem, but also the problem of adverse effects on the global environment, the use of organic solvents has come to be regulated.

Therefore, in recent years, an aqueous epoxy resin composition which does not use an organic solvent has come into the limelight. This aqueous epoxy resin composition is obtained by dispersing or dissolving an epoxy resin and a curing agent in water, and generally, a method of emulsifying and dispersing using a surfactant is adopted.

However, the aqueous epoxy resin composition emulsified by using such a surfactant may not only be inferior in storage stability depending on the kind and amount of the surfactant, but also the aqueous epoxy resin composition. The cured product obtained from has a tendency that the physical properties of the cured product are inferior as compared with the case of using a solvent-based composition, and in particular, because of poor water resistance and adhesiveness, there is a drawback of inferior corrosion resistance. . These disadvantages are:
It is considered that the adverse effect of the surfactant remaining in the cured product is one cause, and there has been a demand for an aqueous epoxy resin composition in which the amount of the surfactant used is reduced.

It is well known to use a modified product obtained by adding an epoxy compound to a polyamine compound as a curing agent,
It is also known that those with a low metamorphic ratio have relatively good dispersibility in water. However, when the modification ratio is small, the corrosion resistance of the cured product tends to be poor. Conversely, when the modification ratio is large, the corrosion resistance is improved but the dispersibility in water is insufficient. It was

It has also been proposed to introduce a polyether chain into the molecule to improve the dispersibility in water. For example, Japanese Patent Publication No. 61-40688 discloses a polyalkylene polyol and an excess equivalent amount of polyepoxide. It has been proposed to use a reaction product of an adduct of the above with an organic polyamine as a curing agent, and in JP-A-4-351628, a reaction product of a polyalkylene polyol, a lactone and an excess equivalent amount of a polyepoxide with a reaction product of an organic polyamine. Has been proposed as a curing agent.

However, since the curing agents described in these publications contain a large hydrophobic group in the molecule, the resulting aqueous epoxy resin composition tends to have poor storage stability, and the storage stability is improved. In order to do so, it is necessary to use a relatively high molecular weight polyether polyol, but when a high molecular weight polyether polyol was used, the corrosion resistance of the cured product was inferior, which was not practically satisfactory.

Therefore, an object of the present invention is to provide a curing agent which exhibits good dispersibility and storage stability when an aqueous epoxy resin composition is prepared and which is excellent in corrosion resistance of the cured product. .

[0010]

Means for Solving the Problems As a result of intensive studies, the present inventors have found that a modified product obtained by addition-modifying a specific polyamine compound having an oxypropylene chain with a specific polyglycidyl ether compound having an oxypropylene chain. It was found that the above object can be achieved when used as a curing agent for an aqueous epoxy resin.

The present invention has been made on the basis of the above findings and comprises at least one polyamine compound represented by the following general formula (I) represented by the general formula (I): 4] (same as [Chemical Formula 2] above)
The ratio of at least one polyglycidyl ether compound represented by I) is 0.01 to 0.4 epoxy groups of the polyglycidyl ether compound per one active hydrogen of the amino group of the polyamine compound. The present invention provides a curing agent for an aqueous epoxy resin, which is formed by addition modification of the above.

[0012]

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[0013]

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[0014]

BEST MODE FOR CARRYING OUT THE INVENTION The curing agent for an aqueous opoxy resin of the present invention will be described in detail below. In the polyamine compound represented by the above general formula (I) used in the present invention, the alkylene group having 2 to 4 carbon atoms represented by R ₁ and R ₂ includes ethylene, 1,2-propylene and 1,3.
-Propylene, 1,2-butylene, 1,3-butylene and 1,4-butylene, and R ₂ may be methylene, which is a residue of the divalent to hexavalent polyol represented by A. Is, for example, ethylene glycol, 1,2-
Propylene glycol, 1,3-propylene glycol, 1,3-butylene glycol, 1,4-butylene glycol, 1,6-hexanediol, neopentyl glycol, benzenedimethanol, cyclohexanedimethanol, glycerin, trimethylolethane, tri Examples thereof include residues obtained by removing a hydroxyl group from methylolpropane, pentaerythritol, dichryserine, ditrimethylolpropane, sorbitol, mannitol, and dipentaerythritol. In particular, it is preferable to use a compound in which A has a hydroxyl group removed from a divalent or trivalent polyol.

The polyamine compound represented by the above general formula (I) is known, and for example, a polyol obtained by adding propylene oxide to a polyol giving a residue represented by A, polypropylene glycol or polyoxypropylene / oxyethylene glycol. A method of aminating the hydroxyl group at the terminal of a polyol having a 1,2-oxypropylene group such as polyoxypropylene / oxybutylene glycol, and adding acrylonitrile to the hydroxyl group at the terminal and then reducing it to convert the nitrile group into an amino group. It can be manufactured by a method or the like. Further, in order to improve the dispersibility in water or the water resistance of the obtained cured product, the polyalkylene glycol moiety is replaced by a method of replacing less than 40% by weight of propylene oxide to be added with ethylene oxide or butylene oxide. It is possible to make less than 40% by weight of 1,2-ethyleneoxy group, 1,2-butyleneoxy group or 1,4-butyleneoxy group, but the content of 1,2-propyleneoxy group is 60%. If it is less than wt%, the anticorrosion property is poor.

In the polyamine compound represented by the general formula (I), n (the number of oxyalkylene groups) is 1 to 50, but the total number of n in the molecule is 2 to 100, particularly 3 to 50. When the total of n is larger than this, the anticorrosive property tends to be poor.

Therefore, typical examples of the polyamine compound represented by the above general formula (I) include compounds No. I-1 to No. I-7 as shown in the following [Chemical formula 5].

[0018]

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The above general formula (I
In the polyglycidyl ether compound represented by I), examples of the residue of the divalent to tetravalent polyol represented by B include ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol and 1,3. −
Butylene glycol, 1,4-butylene glycol,
1,6-hexanediol, neopentyl glycol,
Benzenedimethanol, cyclohexanedimethanol,
Glycerin, trimethylol ethane, trimethylol propane, pentaerythritol, dichryserine, the residue obtained by removing the hydroxyl group from ditrimethylol propane, examples of the residue of the polyphenol, for example, resorcinol, hydroquinone, pyrocatechol, phloroglucinol, dihydroxy. Naphthalene, biphenol, methylenebisphenol (bisphenol F), methylenebis (orthocresol), ethylidene bisphenol, isopropylidene bisphenol (bisphenol A), isopropylidene bis (orthocresol), tetrabromobisphenol A, bis (hydroxyphenyl) phenylmethane, bis (Hydroxyphenyl) cyclohexylmethane, cyclohexylidene bisphenol, thiobispheno , Sulfo bisphenol (bisphenol S), oxy bisphenol, 1,3-bis (4-hydroxycumyl) benzene, 1,4-bis (4
-Hydroxycumyl) benzene is a residue obtained by removing a hydroxyl group. In particular, it is preferable to use a compound in which B is a residue obtained by removing a hydroxyl group from a divalent polyol or a bisphenol compound, because an epoxy resin composition excellent in dispersibility, storage stability and corrosion resistance can be obtained. Therefore,
The polyglycidyl ether compound is preferably a diglycidyl ether of a propylene oxide adduct of a bisphenol compound or a diglycidyl ether of polypropylene glycol.

The polyglycidyl ether compound represented by the above general formula (II) is known and, for example, polypropylene glycol, polyoxypropylene / oxyethylene glycol or polyoxypropylene / oxybutylene glycol or the residue represented by B. It can be easily produced by glycidyl etherification of the terminal hydroxyl group of the polyol obtained by adding propylene oxide to the polyol or polyphenol which gives a group. Further, in order to improve the dispersibility in water or the water resistance of the obtained cured product, the polyalkylene glycol moiety is replaced by a method of replacing less than 40% by weight of propylene oxide to be added with ethylene oxide or butylene oxide. Less than 40% by weight of 1, 2
-Ethyleneoxy group, 1,2-butyleneoxy group or 1,4-butyleneoxy group is also possible,
If the content of the 1,2-propyleneoxy group is less than 60% by weight, the anticorrosion property is poor.

Therefore, as typical examples of the polyglycidyl ether compound represented by the above general formula (II), compounds No. II-1 to II-7 shown in the following [Chemical formula 6] to [Chemical formula 12] are listed. To be

[0022]

[Chemical 6]

[0023]

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[0024]

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[0025]

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[0026]

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[0027]

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[0028]

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The curing agent of the present invention comprises at least one polyamine compound represented by the general formula (I) and at least one polyglycidyl ether compound represented by the general formula (II). 0.01 to 0.4, preferably 0.02, of epoxy groups of the polyglycidyl ether compound per 1 active hydrogen of the amino group of
It is formed by additional transformation at a ratio of ~ 0.3 pieces,
If the addition modification ratio is less than the lower limit of the above range, there is a drawback that the corrosion resistance of the water-based epoxy resin composition containing a curing agent is inferior, and if it exceeds the upper limit of the above range, gel at the time of production. It may turn into unusable.

Further, a small amount of other polyamines can be used together with the polyamine compound represented by the above general formula (I).

Other polyamines mentioned above include ethylenediamine, 1,2-propylenediamine, 1,3-propylenediamine, 1,4-butylenediamine, hexamethylenediamine, 2,4,4-trimethylhexamethylenediamine, Aliphatic polyamines such as diethylenetriamine, dipropylenetriamine, triethylenetetramine, tetraethylenepentamine, dipropylenetriamine, dimethylaminopropylamine, diethylaminopropylamine; menthenediamine, 1,3-bis (aminomethyl) cyclohexane, isophoronediamine , N
-3-Aminopropylcyclohexylamine, 1,4-
Diaminocyclohexane, 2,4-diaminocyclohexane, bis (aminocyclohexyl) methane, 1,3-
Alicyclic polyamines such as bis (aminocyclohexylpropane), bis (3-methyl-4-aminocyclohexyl) methane and 1,4-bis (ethylamino) cyclohexane; m-xylylenediamine, p-xylylenediamine, 4 -(1-aminoethyl) aniline, metaphenylenediamine, diaminodiphenylmethane, diaminodiphenylsulfone, bis (3-ethyl-4-amino-5)
-Methylphenyl) methane, 1,4-bis (2- (3,
Examples include aromatic polyamines such as 5-dimethyl-4-aminophenyl) propyl) benzene.

The curing agent of the present invention, as described above,
The polyamine compound represented by the general formula (I) is added and modified with the polyglycidyl ether compound represented by the general formula (II). Other modification treatments can be applied within a range that does not impair the purpose. This modification treatment is not particularly limited, but epoxy addition for reacting a mono- or polyepoxy compound other than the polyglycidyl ether compound represented by the general formula (II) with an amino group, Mannich reaction for reacting phenols and formaldehyde. , Amide formation by reacting a carboxylic acid such as dimer acid, and Michael addition for adding an olefin compound such as acrylonitrile to an amino group.

The epoxy resin which is cured by the curing agent of the present invention may be a compound which has an average of more than one epoxy group in the molecule which is usually used, and its structure etc. is not particularly limited. In particular, an epoxy resin having an average of more than one glycidyl group such as glycidyl ether group, glycidyl ester group and glycidylamino group in the molecule is preferable.

The epoxy resin having a glycidyl ether group is obtained by converting a phenolic or alcoholic hydroxyl group into a glycidyl ether by a known method, and examples thereof include resorcinol, hydroquinone, pyrocatechol, phloroglucinol, dihydroxynaphthalene, and the like. Biphenol, methylenebisphenol (bisphenol F), methylenebis (orthocresol), ethylidene bisphenol, isopropylidene bisphenol (bisphenol A), isopropylidene bis (orthocresol), tetrabromobisphenol A, bis (hydroxyphenyl) phenylmethane, bis (hydroxy) (Phenyl) cyclohexylmethane, cyclohexylidene bisphenol, thiobisphenol, sulfobisphenol (biphenyl) Phenol S), oxy bisphenol, 1,3-bis (4-hydroxycumyl) benzene, 1,4-bis (4-hydroxycumyl) benzene,
Phenol-polyglycidyl ethers of mononuclear or polynuclear polyphenols such as formaldehyde condensates and ethylene glycol, propylene glycol, butylene glycol, hexanediol, polyglycol, thiodiglycol, glycerin, trimethylolpropane, pentaerythritol, sorbitol, Bisphenol A
-Glycidyl ethers of polyhydric alcohols such as ethylene oxide adducts.

Examples of the epoxy resin having a glycidyl ester group include maleic acid, fumaric acid, itaconic acid, succinic acid, glutaric acid, suberic acid, adipic acid, azelaic acid, sebacic acid, dimer acid, trimer acid and phthalic acid. Glycidyl ester of aliphatic, aromatic or alicyclic polybasic acid such as acid, isophthalic acid, terephthalic acid, trimellitic acid, trimesic acid, pyromellitic acid, tetrahydrophthalic acid, hexahydrophthalic acid, endomethylenetetrahydrophthalic acid And homopolymers or copolymers of glycidyl methacrylate and the like.

Examples of the epoxy resin having a glycidylamino group include N, N-diglycidylaniline and bis (4- (N-methyl-N-glycidylamino).
Phenyl) methane and the like.

Other hardeners of the present invention include epoxidized soybean oil, epoxidized linseed oil, epoxidized safflower oil,
Epoxidized natural oils and fats such as epoxidized tall oil, vinylcyclohexene diepoxide, dicyclopentadiene diepoxide, 3,4-epoxycyclohexylmethyl-
3,4-epoxycyclohexanecarboxylate,
3,4-epoxy-6-methylcyclohexylmethyl-
Epoxidized cyclic olefin compounds such as 3,4-epoxy-6-methylcyclohexanecarboxylate, bis (3,4-epoxy-6-methylcyclohexylmethyl) adipate, epoxidized polybutadiene, epoxidized styrene-butadiene copolymer, etc. The epoxidized conjugated diene polymer, the heterocyclic compound such as triglycidyl isocyanurate, and the like can be effectively used.

These epoxy resins may be used alone or in admixture of two or more, and if necessary, a solvent, a monoepoxy compound or the like may be added.
Further, these epoxy resins may be so-called emulsified epoxy resins which are emulsified in advance using a surfactant such as polyoxyethylene alkylphenyl ether compound.

The curing agent of the present invention is the above-mentioned epoxy resin and a reactive diluent, a non-reactive diluent, a filler, a reinforcing agent, a pigment, a dye, a solvent, a plasticizer, a leveling agent which is used as necessary. , A thixotropic agent, a flame retardant, a release agent, and other commonly used additives can be emulsified and / or dispersed in water to form a curable composition. In this case, the curing agent and the epoxy resin are separately prepared. A method of mixing these after emulsifying and / or dispersing, a method of emulsifying and / or dispersing one while emulsifying and / or dispersing the other, or a method of simultaneously emulsifying and / or dispersing both Either can be adopted.

The curable composition obtained as described above can be prepared by a suitable method such as brush coating, roller, spraying, spatula coating, press coating, doctor blade coating, electrodeposition coating or dip coating. When applied to a substrate, it is used as an undercoat or intermediate coating, a filler, a sealant, a protective coating, a coating material, a sealing material, a mortar, a coating material, etc. It is useful as a paint.

[0041]

The present invention will be described in more detail with reference to the following examples. However, the present invention is not limited by the following examples. As the polyamine compound and polyglycidyl ether compound used below, those exemplified above were used.

Production Example 1 A polypropylene glycol diamine compound (No. I) was placed in a glass flask equipped with a thermometer, a stirrer and a cooling tube.
-1) 124 g and 79 g of diglycidyl ether of bisphenol A propylene oxide 5 mol adduct of epoxy equivalent 315 (No. II-2) (active hydrogen of amino group 1
The ratio of epoxy groups to 0.125) was taken, and the mixture was stirred at 80 ° C. for 2 hours to add epoxy. Water (51 g) was added thereto, and the mixture was sufficiently stirred and dispersed to obtain a solid content of 80% by weight and an active hydrogen equivalent (WPH) of 14%.
A curing agent composition of 5 (Curing agent 1) was obtained.

Production Examples 2 to 23 Epoxy addition modification was performed in the same manner as in Production Example 1 except that the kind and molar ratio of the polyamine compound and / or the diglycidyl ether compound were changed as shown in [Table 1] below. Water was added to prepare a curing agent composition having a solid content of 80% by weight. Further, the dispersibility when water was added was evaluated, and a product in which a uniform dispersion was obtained was represented by ◯, and a part or all of which was separated into two layers was represented by x. In the following [Table 1], EP-1 is a bisphenol diglycidyl ether type epoxy resin having an epoxy equivalent of 190, mX
DA is metaxylylenediamine, and TTA is triethylenetetramine.

[0044]

[Table 1]

Use Example 1 To 105 parts by weight of a bisphenol A glycidyl ether type self-emulsifying type epoxy emulsion (epoxy equivalent (WPE) 1050) having a solid content of 50%, the curing agent composition shown in the following [Table 2] was used. The active hydrogen was added to the base in an equivalent amount, mixed sufficiently, and then coated on a sandblast plate so that the dry film thickness was 50 μ, and dried and cured under the conditions of room temperature and one week. The obtained coating film was subjected to a salt spray test (SST test) according to JIS K5400, and its surface condition was observed with time. The evaluation was performed according to the following criteria. ○: No abnormality △: Some blister occurred ×: Blister and rust occurred

The curing agent whose dispersibility was x in the above production example was used as a dispersion having a solid content of 80% with polyoxyethylene nonylphenyl ether.

[0047]

[Table 2]

USE EXAMPLE 2 As the epoxy resin, the epoxy emulsion or epoxy resin shown in the following [Table 3] and water were used, and the curing agent 1 was used.
The same test as in Use Example 1 was carried out except that the active hydrogen was used so as to be equivalent to the epoxy group. The results are shown in Table 3 below.

[0049]

[Table 3]

As is clear from the above results, the polyamine compound having an oxypropylene chain [the polyamine compound represented by the general formula (I)] and the polyglycidyl ether compound having an oxypropylene chain [the general formula (II)] The poly (glycidyl ether compound represented by) is a hardener for an aqueous epoxy resin of the present invention, which is composed of an addition modification product of a specific ratio, and is not only excellent in dispersibility in water, but also an epoxy resin cured film using this is anticorrosive. Excellent in properties, and no blister or rust is observed even after a long period of severe salt spray resistance test.

On the other hand, when a curing agent containing a polyamine compound having no oxypropylene chain and / or a polyglycidyl ether compound having no oxypropylene chain is used, the corrosion resistance of the cured epoxy resin film becomes insufficient. In a short time, blister and rust will be generated. Further, if the ratio of the polyglycidyl ether compound is too large, gelation occurs and it becomes impossible to use.

[0052]

The curing agent for aqueous epoxy resin of the present invention is
It is possible to provide an epoxy resin cured coating having excellent dispersibility in water and excellent corrosion resistance.

Claims (3)

[Claims] 1. At least one polyamine compound represented by the general formula (I) of the following [Chemical formula 1] and at least one polyglycidyl ether compound represented by the general formula (II) of the following [Chemical formula 2] A curing agent for an aqueous epoxy resin, wherein the polyamine compound is additionally modified with 0.01 to 0.4 epoxy groups of the polyglycidyl ether compound to 1 active hydrogen of the amino group of the polyamine compound. Embedded image Embedded image 2. The polyglycidyl ether compound,
The curing agent for an aqueous epoxy resin according to claim 1, which is a diglycidyl ether of a propylene oxide adduct of a bisphenol compound. 3. The polyglycidyl ether compound,
The curing agent for an aqueous epoxy resin according to claim 1, which is a diglycidyl ether of polypropylene glycol.