JPH08337750A - Resin composition for coating - Google Patents

Abstract

PURPOSE: To obtain the subject composition consisting essentially of an epoxy- polyamine resin obtained by introducing a specific diepoxide compound into a bisphenol type epoxy resin skeleton, having suitability for thick film coating and highly corrosive property and especially useful for cathode electrodeposition coating. CONSTITUTION: This resin composition consists essentially of an epoxy-polyamine resin obtained by forming an adduct of (B) an amine compound having active hydrogen as a main component to (A) an epoxy resin obtained by reacting (I) a diepoxide compound of the formula [R is CH3 or CH2 CH3 ; (m+n) is an integer of 1-6] with (ii) bisphenols and, as necessary, (iii) a bisphenoldiglycidyl ether. Furthermore, a method comprising reacting the terminal hydroxy group of a resin obtained by reacting the component (I) with the component (ii) exceeding an equivalent amount with the component (iii) exceeding an equivalent amount and adding the component B to the terminal oxysilane group of the resultant epoxy resin is especially preferable as the adduct formation reaction.

Description

Detailed Description of the Invention

[0001]

The present invention relates to a novel coating resin composition, and more particularly to a coating resin composition having improved suitability for thick film coating and improved anticorrosion property, which is particularly suitable for cathodic electrodeposition coating.

[0002]

2. Description of the Related Art As a resin composition for a cathodic electrodeposition coating, an epoxy-polyamine obtained by reacting an epoxy group-containing resin with a polyamine, as disclosed in, for example, JP-A-54-93024. A resin composition in which a resin and a polyisocyanate curing agent blocked with alcohols are combined is common. As the epoxy group-containing resin, from the viewpoint of anticorrosion, a resin obtained by polymerizing bisphenol A diglycidyl ether into a high molecular weight using bisphenol A is usually used. Further, a partially soft polyester, polyether, or epoxy resin, polyamide,
A plasticizer obtained by introducing a plastic modifier such as polybutadiene or a butadiene-acrylonitrile copolymer has been put into practical use.

[0003]

Recently, in the field of electro-deposition coating of automobile bodies and parts underneath, development of coating materials having suitability for thick film coating and high anticorrosion properties from the viewpoint of aesthetics and coating performance. Demand is growing.

[0004] In order to meet these demands, when a conventional plastic modifier of an epoxy resin is increased in order to provide a thick film coating suitability in cathodic electrodeposition coating, a component having low corrosion resistance is introduced into the resin, and sufficient resin is introduced. On the other hand, when the anticorrosion property is not obtained, and when the amount of the plastic modifier is reduced to reinforce the anticorrosion property, there is a problem that the suitability for thick film coating cannot be obtained.

[0005]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies with the aim of obtaining a resin composition which is suitable for thick film coating and has a high level of anticorrosion, and as a result, has 3 to 4 carbon atoms. It has been found that the above object can be achieved by using an epoxy resin into which a specific amount of alkylene oxide has been introduced.

According to the present invention, however, (a) the following general formula (I)

[0007]

Embedded image

In the formula, R represents CH ₃ or CH ₂ CH ₃ , and m + n is an integer of 1 to 6, a (b) bisphenol compound and, if necessary, a (c) bis compound. Provided is a coating resin composition comprising (d) an epoxy-polyamine resin obtained by adding an amine compound having active hydrogen to an epoxy resin obtained by reacting phenol diglycidyl ether as a main component. It

The diepoxide compound (a) represented by the general formula (I) used in the present invention is prepared by adding a 1,2-alkylene oxide having 3 to 4 carbon atoms to bisphenol A, and then adding the epoxy epoxide with epichlorohydrin. The diepoxide compound obtained in this way has a thick-film coating because the alkyleneoxy structure, which is a plastic component, forms a repeating structure at a relatively short interval with the hard bisphenol A structure. It is considered to have suitability and exhibit high corrosion protection.

When ethylene oxide is used as the alkylene oxide to be added to bisphenol A,
Such an advantage is not obtained, and 1 to 3 carbon atoms,
It has been found in the present invention that the above performance can only be met by using 2-alkylene oxides, ie 1,2-propylene oxide or 1,2-butylene oxide. When ethylene oxide is used as the alkylene oxide, the obtained diepoxide compound has low hydrophobicity and deteriorates the corrosion resistance. On the other hand, alkylene oxides having 5 or more carbon atoms are generally difficult to obtain and have many carbon atoms. When an alkylene oxide is used, the obtained resin is softened, and the corrosion resistance tends to be deteriorated.

The total number of repeating units m and n of the alkyleneoxy group in the diepoxy compound of formula (I) is (m + n)
Is an integer in the range of 1 to 6, preferably in the range of 1 to 3. If the total number of repeating units (m + n) exceeds 6, the resulting resin tends to be soft and the anticorrosive property tends to deteriorate, which is not preferable.

In the present invention, the diepoxide compound (a) represented by the above formula (I) is reacted with a bisphenol (b) and optionally a bisphenol diglycidyl ether (c), and further has active hydrogen. An epoxy-polyamine resin is obtained by adding the amine compound (d).

The reaction modes for obtaining the epoxy-polyamine resin include those shown below.

(I) reacting a diepoxide compound (a) with a bisphenol (b) in an amount less than equivalent to an amine compound (d) at the terminal oxirane group of the epoxy resin obtained;
(Ii) reacting the diepoxide compound (a) with the bisphenols (b) in excess of the equivalent amount to the terminal hydroxyl groups of the resin, which is reacted with bisphenol diglycidyl ether (c) in excess of the equivalent amount, A method of adding an amine compound (d) to a terminal oxirane group of the obtained epoxy resin; (iii) a total of oxirane groups of diepoxide compound (a), bisphenol diglycidyl epoxy (c) and (a) + (c). On the other hand, the terminal oxirane group of the resulting epoxy resin is simultaneously reacted with an amount of a bisphenol (b) having an amount of hydroxyl groups less than the equivalent, and an amine compound (d)
And how to add.

In the above methods (i), (ii) and (iii), the addition of the amine compound (d) can be carried out at the same time when the epoxy resin has a high molecular weight. Of the above reaction methods (i), (ii) and (iii), (ii)
Is particularly preferred in terms of resin design and control.

Bisphenols (b) used in the above reaction
Typical examples include bis (4-hydroxyphenyl) -2,2
-Propane, bis (4-hydroxyphenyl) -1,1-
Ethane, bis (4-hydroxyphenyl) -methane, 4,
4'-dihydroxydiphenyl ether, 4,4'-dihydroxydiphenyl sulfone, bis (4-hydroxyphenyl) -1,1-isobutane, bis (4-hydroxy-3-t-butylphenyl) -2,2- Propane etc. are mentioned.

The bisphenol diglycidyl ether (c) has a number average molecular weight of at least about 32.
0, preferably in the range of about 340-2000 and an epoxy equivalent of at least about 160, preferably about 170-100.
Bisphenol diglycidyl ether within the range of 0 is suitable, especially the following formula

[0018]

Embedded image

The bisphenol A-type diglycidyl ether represented by the formula (1) is particularly preferable in terms of cost and corrosion resistance.

When an epoxy resin is produced by reacting the diepoxide compound (a), the bisphenol (b) and, if necessary, (c) bisphenol diglycidyl ether, the amount of the diepoxide compound (a) used is as described above. It is preferred that the content be 10% by weight or more based on the total amount of the components (a), (b) and (c). If the amount of the diepoxide compound (a) used is less than 10% by weight, the suitability for thick film coating tends to be not obtained.

The epoxy resin obtained is 1000-500
It is preferable to have a number average molecular weight in the range of 0 from the viewpoint of corrosion resistance and suitability for thick film coating.

The reaction between the oxirane group and the hydroxyl group to obtain the above epoxy resin can be carried out by a method known per se, for example, the presence of a catalyst such as a basic amino compound such as dimethylbenzylamine, tributylamine, triethylamine and the like. It can be carried out by heating at a temperature of about 50 ° C. to about 200 ° C. for about 1 to about 15 hours.

The epoxy resin obtained as described above can be converted into an epoxy-polyamine resin by adding an amine compound (d) having active hydrogen. As the amine compound (d) having active hydrogen,
The epoxy resin having an active hydrogen capable of reacting with an oxirane group, such as an aliphatic, alicyclic or aromatic-aliphatic primary or secondary amine, alkanolamine or tertiary amine salt, has an amino group or An amine compound into which a quaternary ammonium salt can be introduced is given. Representative examples of these amine compounds having active hydrogen include the following.

(1) A primary amino group of an amine compound containing one secondary amino group such as diethylenetriamine, hydroxyethylaminoethylamine, ethylaminoethylamine and methylaminopropylamine and one or more primary amino groups. , A compound modified by heating reaction with a ketone, aldehyde or carboxylic acid at a temperature of, for example, about 100 to 230 ° C. to give an aldimine, ketimine, oxazoline or imidazoline; (2) diethylamine, diethanolamine, di-n
-Or-iso-propanolamine, N-methylethanolamine, N-ethylethanolamine, etc.
Secondary amine-containing compounds obtained by adding a monoalkanolamine such as monoethanolamine and dialkyl (meth) acrylamide by Michael addition reaction; (4) monoethanolamine, neopentanol Compounds in which the primary amino group of alkanolamine such as amine, 2-aminopropanol, 3-aminopropanol, 2-hydroxy-2 '(aminopropoxy) ethyl ether is modified to ketimine; (5) dimethylethanolamine, triethylamine, trimethylamine And salts of tertiary amines such as triisopropylamine, methyldiethanolamine and the like with organic acids such as acetic acid and lactic acid.

The amine compound having an active hydrogen has an oxirane group in the epoxy resin, for example, about 30%.
The epoxy-polyamine resin can be obtained by reacting at a temperature of about 160 ° C. for about 1 to about 5 hours. Further, as described above, the addition of the amine compound to the epoxy resin can be performed simultaneously with the increase in the molecular weight of the epoxy resin.

The amount of the amine compound having active hydrogen to be used is preferably such that the amine value of the epoxy-polyamine resin of the present invention is in the range of 15 to 100.
When the amine value is less than 15, it is difficult to disperse the resin in water. When the amine value exceeds 100, the water resistance of the resulting coating film tends to be poor.

The above epoxy-polyamine resin also comprises
For example, by reacting with a reaction agent such as a tertiary amine salt, a monocarboxylic acid, a secondary sulfide salt, a monophenol or a monoalcohol, the water dispersibility can be adjusted or the smoothness of the coating film can be improved.

Further, by introducing a crosslinkable functional group such as a block isocyanate group, a β-hydroxycarbamate group, an α, β-unsaturated carbonyl group, an N-methylol group into the epoxy-polyamine resin, Crosslinkability can also be imparted.

The above-mentioned reaction with the reagent and the introduction of the crosslinkable functional group may be carried out before adding the amine compound having active hydrogen to the epoxy resin.

Epoxy obtained as described above
An external crosslinking agent can be used in combination with the polyamine resin.
Examples of the external crosslinking agent that can be used in combination include compounds having two or more crosslinking groups in one molecule, such as block polyisocyanate, β-hydroxycarbamic acid ester of polyamine, malonic ester derivative, methylolated melamine,
Methylolated urea and the like can be mentioned. Mixing ratio of epoxy-polyamine resin and these external crosslinking agents
The (solid content ratio) is preferably in the range of 100/0 to 60/40.

In order to make the above-mentioned epoxy-polyamine resin water-soluble or water-dispersible, the amino group is protonated with a water-soluble organic acid such as formic acid, acetic acid or lactic acid and dissolved or dispersed in water. Good.

Although the amount (neutralization value) of the acid used for protonation cannot be strictly defined, generally, the electrodeposition property is within the range of about 5 to 40 KOH mg, particularly 10 to 20 KOH mg per 1 g of resin solids. Above. The aqueous solution or aqueous dispersion thus obtained is particularly suitable for cathodic electrodeposition coating, and in this case, if necessary, a pigment, a solvent, a curing catalyst, a surfactant, etc. may be added and used. .

As a method and an apparatus for performing electrodeposition coating on an object to be coated using the above-mentioned aqueous solution or aqueous dispersion, known methods and apparatuses conventionally used per se in cathodic electrodeposition coating can be used. it can. At this time, it is desirable to use the object to be coated as a cathode and the stainless steel or carbon plate as the anode. Electrodeposition conditions that can be used are not particularly limited, but generally, bath temperature: 20 to
30 ° C., voltage: 100 to 400 V (preferably 200 to 3
00V), current density: 0.01 to 3 A / dm ² , energization time: 1
~ 5 minutes, pole area ratio (A / C): 2/1 ~ 1/2, distance between poles:
It is desirable to electrodeposit 10 to 100 cm under stirring.

The coating film deposited on the cathode object can be baked and cured at about 140 ° C. to about 180 ° C. after cleaning.

Hereinafter, the present invention will be described more specifically with reference to examples. Hereinafter, “parts” and “%” indicate “parts by weight” and “% by weight”, respectively.

Production Example 1 Propylene oxide-modified bisphenol A diglycidyl ether (Note 1) 5 in a reaction vessel equipped with a thermometer, a stirrer, a reflux condenser and a nitrogen gas inlet under nitrogen gas injection.
25 parts, 342 parts of bisphenol A and 80% of active ingredient
Of monoethylamine and methyl isobutyl ketone, and 36 parts of a methyl isobutyl ketone solution of ketimine was reacted at 160 ° C. until the epoxy group disappeared.

Further, the epoxy equivalent of this product is about 19
0 bisphenol A diglycidyl ether 665 parts and 232 parts of a methylisobutylketone solution of ketimine of 80% monoethanolamine and methylisobutylketone were added, and the epoxy group concentration was 0.2 at 140 ° C.
The reaction was allowed to reach 7 mmol / g. As a result, an epoxy resin liquid having a number average molecular weight of about 1500 was obtained. Then, the mixture was diluted with 365 parts of ethylene glycol monobutyl ether and cooled, and when 100 ° C was reached, 100 parts of a solution of 80% diethylenetriamine in methylisobutylketone diketimine in methylisobutylketone was added.
React at 00 ° C until the viscosity rise stops and solid content 81%
To obtain an epoxy-polyamine resin solution. This product is treated with ethylene glycol monobutyl ether at a solid concentration of 50.
%, And the Gardner viscosity (25 ° C.) was W.

(Note 1) Propylene oxide-modified bisphenol A diglycidyl ether [manufactured by Sanyo Chemical Industries, trade name:
Glicier BPP-350, epoxy equivalent 340,
M + n = 2 to 3 in the formula (I)].

Production Example 2 Propylene oxide-modified bisphenol A diglycidyl ether (Note 1) 840 parts, a bisphenol A diglycidyl ether having an epoxy equivalent of about 190, 608 parts, in a reaction apparatus similar to that of Production Example 1 under nitrogen gas injection. 410 parts of bisphenol A and 1.9 parts of dimethylbenzylamine were mixed and reacted at 160 ° C. until the epoxy group concentration reached 1.1 mmol / g. This gives a number average molecular weight of about 19
00 epoxy resin liquid was obtained. Then dilute and cool with 420 parts of ethylene glycol monobutyl ether, and
When the temperature reached 0 ° C., 147 parts of diethanolamine was charged, the temperature was raised to 120 ° C., and the reaction was carried out at the same temperature until the epoxy group concentration reached 0.4 mmol / g. Of N, N-dimethylaminopropylacrylamide with monoethanolamine (ethylene glycol monobutyl ether solution) 10
Nine parts were charged and reacted at 100 ° C. until there was no increase in viscosity to obtain an epoxy-polyamine resin solution having a solid content of 82%.

The Gardner viscosity (25 ° C.) was Y when this product was adjusted to a solid concentration of 50% with ethylene glycol monobutyl ether.

Production Example 3 In the same reactor as in Production Example 1, 476 parts of polypropylene glycol diglycidyl ether having an epoxy equivalent of about 317, 342 parts of bisphenol A, and monoethanolamine containing 80% of the active ingredients and methyl isobutyl were blown with nitrogen gas. Methyl isobutyl ketone solution of ketimine with ketone 3
6 parts were charged and reacted at 160 ° C. until the epoxy group disappeared.

Furthermore, the epoxy equivalent of this product is about 19
665 parts of bisphenol A diglycidyl ether and 232 parts of a 80% active ingredient of a solution of ketimine in 80% monoethanolamine and methyl isobutyl ketone in methyl isobutyl ketone were added.
The reaction was allowed to reach 28 mmol / g.

As a result, an epoxy resin liquid having a number average molecular weight of about 1500 was obtained. This product was diluted with 365 parts of ethylene glycol monobutyl ether and cooled to 100 ° C.
Then, 100 parts of a 80% active ingredient of diethylenetriamine in methyl isobutyl ketone diketimine in 100 parts of methyl isobutyl ketone was added, and the mixture was reacted at 100 ° C. until the increase in viscosity was stopped to obtain an epoxy-polyamine resin solution having a solid content of 81%. .

The Gardner viscosity (at 25 ° C.) when this was adjusted to a solid content of 50% with ethylene glycol monobutyl ether was V.

Production Example 4 An ethylene oxide-modified bisphenol A having an epoxy equivalent of about 300 was introduced into the same reactor as in Production Example 1 while blowing nitrogen gas.
Charge 450 parts of diglycidyl ether (Note 2), 342 parts of bisphenol A and 36 parts of methylisobutylketone ketimine (methylisobutylketone solution) of monoethanolamine containing 80% of the active ingredient, and react at 160 ° C until the epoxy group disappears. Let

Furthermore, the epoxy equivalent of this product is about 19
665 parts of bisphenol A diglycidyl ether and 232 parts of a 80% active ingredient of a solution of ketimine in 80% monoethanolamine and methyl isobutyl ketone in methyl isobutyl ketone were added.
The reaction was allowed to reach 29 mmol / g. As a result, an epoxy resin liquid having a number average molecular weight of about 1500 was obtained.
Then, this product was diluted with 350 parts of ethylene glycol monobutyl ether and cooled, and when the temperature reached 100 ° C., methyl isobutyl ketone solution of diethylene thymine ketone diketimine containing 80% of the active ingredient 100%.
Then, the mixture was reacted at 100 ° C. until the increase in viscosity stopped, to obtain an epoxy-polyamine resin solution having a solid content of 81%.
Gardner viscosity (25 ° C) when this was adjusted to a solid concentration of 50% with ethylene glycol monobutyl ether.
Was Y.

(Note 2) Ethylene oxide-modified bisphenol A diglycidyl ether [manufactured by Sanyo Chemical Co., Ltd., trade name: Glycier BPE-300, epoxy equivalent: about 300]

[0048]

【Example】

Examples 1 and 2 and Comparative Examples 1 and 2 Methyl ethyl ketoxime block isophorone diisocyanate was used for the four types of resin solutions obtained in the above production examples, in which the block isocyanate groups were the primary hydroxyl group and primary amino group in the epoxy-polyamine resin. It was blended so as to be equivalent to the total amount of the groups.

Also, polypropylene glycol is added to 100 parts by weight of the solid content of the resin composition compounded as described above.
(Sanyox PP4000, manufactured by Sanyo Chemical Co., Ltd.), 1 part, 0.96 part of acetic acid and 1 part of lead acetate were added, and the mixture was heated to 60 ° C. and gradually added with deionized water while stirring to disperse the resin solids. An emulsion with good stability of 30% was obtained.

3 parts of basic lead silicate, 13 parts of titanium white, 0.3 part of carbon black, 3 parts of clay, 2 parts of dibutyltin oxide, 2 parts of nonionic and 100 parts by weight of the resin solid content of the emulsion thus obtained. One part of a surfactant (trade name: Neugen 142B, manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) was added, the pigment was dispersed with a ball mill until the particle size became 10 μm or less, and then the resin solid content was reduced to 15% with deionized water. Dilute to make

The undiluted steel sheet and the Bt-3080 (zinc phosphate) -treated steel sheet were subjected to cationic electrodeposition coating at a bath temperature of 28 ° C. and a voltage of 250 V for 3 minutes for the four diluted paints obtained as described above. After these electrodeposition coated plates were baked at 160 ° C. for 20 minutes, a corrosion resistance test was conducted.

The resin composition and test results are shown in Table 1 below.

[0053]

[Table 1]

The anticorrosion test in Table 1 was conducted according to the following method.

(Note 4) Salt water spray resistance Cross cut scratches were made on the electrodeposition coating film with a knife so as to reach the substrate, and this was subjected to a test according to JIS Z2371 to measure rust and blister width from knife scratches. I do. The test time was 480 hours for an untreated steel sheet, and Bt-3080.
The treated steel sheets were set for 1000 hours and 1500 hours.

(Note 5) Saltwater immersion resistance The electrodeposited coated plate was immersed in a 5% NaCl aqueous solution, and the change in the plane portion was observed. The immersion time was 480 hours for the untreated steel sheet and 800 hours for the Bt-3080 treated steel sheet.

The evaluation criteria are as follows.

A: There is almost no change.

○: There is a change in the coated surface, but swelling and peeling are less than 5%.

◇: Blisters and peeling are less than 5% to 10%.

Δ: Blisters and peeling are 10% to less than 50%.

X: Swelling and peeling were 50% or more.

[0063]

The coating composition of the present invention comprising an epoxy-polyamine resin in which a diepoxide compound represented by the above formula (I) is introduced into a bisphenol-type epoxy resin skeleton is used for cathodic electrodeposition coating. By using
Under normal electrodeposition coating conditions (voltage: 200 to 300 V, energizing time: 1 to 5 minutes), it is possible to obtain a coating film having a film thickness of 35 μm or more, which is excellent in thick film coating with no coating surface abnormality and excellent in anticorrosion. it can.

Claims (2)

[Claims] 1. (a) The following general formula (I): In the formula, R represents CH ₃ or CH ₂ CH ₃ , m + n is an integer of 1 to 6, and (b) an epoxy resin obtained by reacting a bisphenol with an epoxy resin (d) having an activity of (d) A coating resin composition comprising, as a main component, an epoxy-polyamine resin obtained by adding an amine compound having hydrogen. 2. The diepoxide compound represented by the general formula (I) comprises bisphenol A and 1,2 having 3 to 4 carbon atoms.
The coating resin composition according to claim 1, which is obtained by reacting an epichlorohydrin with an adduct with an alkylene oxide.