JPH0439320A - Epoxy resin for coating - Google Patents

Abstract

PURPOSE:To obtain the title resin soluble or dispersible in solvent of high flashpoint, capable of giving coating films with high corrosion resistance etc. by reaction at specified proportion between a diisocyanate compound and a reaction product of epoxy resin, alkylphenol and aliphatic monocarboxylic acid. CONSTITUTION:The objective resin suitable for coatings etc. can be obtained by reaction between (A) a reaction product formed by reaction between (1) an epoxy resin <=250 in mean epoxy equivalent having at least two epoxy groups, (2) an alkylphenol and (3) an aliphatic monocarboxylic acid at such equivalent ratios (the hydroxyl group of the component 2 + the carboxyl group of the component 3) : (the epoxy group of the component 1) = 1 : (1.8 - 2.5) and (the hydroxyl group of the component 2) : (the carboxyl group of the component 3) = 1 : (0 - 3) and (B) a diisocyanate compound at the equivalent ratio (the hydroxyl group of the component A) : (the isocyanate group of the component B) = 1 : (0.8 - 1.2).

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention provides a coating film that is soluble or stably dispersed in a high flash point solvent and has excellent corrosion resistance, adhesion, flexibility, etc. This invention relates to epoxy resins for paints.

<Prior art and problems to be solved> Epoxy resins have been widely used as resins for anticorrosive paints because of their excellent corrosion resistance, adhesion, chemical resistance, etc. When such epoxy resins are made into paints, they are used by dissolving them in organic solvents, but the organic solvents that dissolve epoxy resins are usually low-containing solvents such as toluene, xylene, methyl ethyl ketone, and ethyl acetate. It was a highly toxic solvent with a low flash point and boiling point. Therefore, there are problems with the painting environment and painting workability, and when it is applied over the old paint film as a repair paint for the old paint film, it dissolves or swells the old paint film, causing paint film defects such as lifting. was there. Therefore,
It is conceivable to use a low-pollution, highly safe organic solvent having a high flash point of about 30° C. or higher as the organic solvent with low fQ for the above-mentioned problem.

However, conventional epoxy resins for paints hardly dissolve or stably disperse in high flash point solvents. In view of the current situation, the present inventors have conducted intensive studies to develop an epoxy resin for paints that is soluble or stably dispersed in high flash point solvents, and as a result, they have arrived at the present invention.

<Means for solving the problem> That is, the present invention provides (a) an epoxy resin having two or more epoxy groups in one molecule and an average epoxy field of about 250 or less; (b) an alkylphenol; , (c) aliphatic monocarboxylic acid, the total equivalent of the hydroxyl group in the alkylphenol (b) and the carboxyl group in the aliphatic monocarboxylic acid (c), and the epoxy group in the epoxy resin (a). the ratio of the equivalent of the hydroxyl group in the alkylphenol (b) to the equivalent of the carboxyl group in the aliphatic monocarboxylic acid (c) is (1:1.8 to 2.5), and (1:
The diisocyanate compound (It) is added to the reaction product (1) obtained by reacting the reaction product (1) at a ratio of 0 to 3).
) and the equivalent of the hydroxyl group in the diisocyanate compound (
The ratio to the equivalent of isocyanate groups in II) is (1:0.
The present invention relates to an epoxy resin for paints obtained by reacting at a ratio of 8 to 1.2).

Since the epoxy resin of the present invention is soluble or stably dispersed in high flash point solvents, paints that combine the two have a good painting environment and workability, and even if the old paint film is overcoated, the old paint film will still remain. This prevents the occurrence of paint film defects such as lifting, and provides a paint film with good corrosion resistance, adhesion, and flexibility.

The present invention will be explained in detail below.

The epoxy resin (a) used in the present invention has 2 epoxy resins per molecule.
It is an epoxy resin having 1 or more epoxy groups and an average epoxy equivalent weight of about 250 or less. If the average epoxy equivalent exceeds 250, the solubility and dispersion stability of the epoxy resin in high flash point solvents will decrease, which is not preferred.

As such epoxy tree Uft (a), for example, Epotote YD-128 and YD-134 manufactured by Tobu Kasei Kogyo Co., Ltd.
, YD-011, YD-014, etc. Bisphenol A/Epichlorohydrin type; Bisphenol F/Epichlorohydrin type commercially available under the trade name Epiclon 830 manufactured by Dainippon Ink Chemical Industries, Ltd.;
Typical examples include AD type epoxy resins commercially available under trade names such as EPOMIK R-710 manufactured by Mitsui Petrochemical Industries, Ltd., but are not limited thereto.

Note that the epoxy resin (a) has an average epoxy equivalent of about 25
For example, an epoxy equivalent of 50 or less is preferable.
Even if epoxy resins around 0 are used together, any mixture of epoxy resins whose average epoxy resin as a whole is 250D or less can be used.

The alkylphenol (b) used in the present invention is a phenol having an alkyl group having about 2 to 8 carbon atoms, and specifically, representative examples include nonylphenonove-paraoctylphenol, paratertiary-butylphenol, etc. It is mentioned as.

The aliphatic monocarboxylic acid (c) used in the present invention is a drying oil fatty acid or a semi-drying oil fatty acid, and specifically, tall oil fatty acid, soybean oil fatty acid, linseed oil fatty acid, dehydrated castor oil fatty acid, cottonseed oil fatty acid, Typical examples include safflower oil fatty acid, tung oil fatty acid, coconut oil fatty acid, palm oil fatty acid, and the like, and saturated fatty acids such as octyl acid and neodecanoic acid and petroleum-based synthetic acids can also be used in combination.

Typical diisocyanate compounds (n) used in the present invention include tolylene diisocyanate, diphenylmethane diisocyanate, xylylene diisocyanate, isophorone diisocyanate, hexamethylene diisocyanate, trimethylhexamethylene diisocyanate, tetramethylene diisocyanate, etc. It is mentioned as.

Next, a typical method for producing the epoxy resin of the present invention will be explained.

First, epoxy resin (a) and alkylphenol (b)
and aliphatic monocarboxylic acid (c) in the presence or absence of a catalyst in a high flash point solvent to give a concentration of about 100 to 20
The mixture is heated to 0°C and reacted until the acid value is 2 KOH/g or less and substantially no alkylphenol is present. The catalysts include alkali catalysts such as sodium hydroxide, potassium hydroxide, and lithium hydroxide; amine or amine salt catalysts such as triethylamine and tripropylamine; tetramethylammonium bromide, tetramethylammonium chloride, and tetraethylammonium bromide. Quaternary ammonium salt catalysts such as , tetraethylammonium chloride, etc. can be typically used.

The reaction between the epoxy resin (a), the alkylphenol (b), and the aliphatic monocarboxylic acid (c) is based on the total equivalent of the hydroxyl group in the alkylphenol (b) and the carboxyl group in the aliphatic monocarboxylic acid (c), and the epoxy The ratio to the equivalent of the epoxy group in the resin (a) is (1:1.8 to 2.5), and the equivalent of the hydroxyl group in the alkylphenol (b),
The ratio to the equivalent of the carboxyl group in the aliphatic monocarboxylic acid (c) is (1:O~3), preferably (1:0.5~2).
．． 5) The reaction must be carried out at a rate of 5).

Regarding the ratio of the total equivalent of hydroxyl groups and carboxyl groups to the equivalent of epoxy groups, if the equivalent of epoxy groups is smaller than the above range, the original coating performance of the epoxy resin cannot be exhibited, while if it is too large, high flash point solvent This is undesirable because the solubility in the liquid decreases and the storage stability deteriorates.

Furthermore, if the amount of carboxyl groups in the equivalent ratio of hydroxyl groups to carboxyl groups is too large than the above range, the corrosion resistance of the coating film will decrease, which is not preferable.

In the reaction product (1) thus obtained, a hydroxyl group is generated by ring opening of the epoxy group, and the diisocyanate compound (n) is reacted with the hydroxyl group. That is, the reaction product (I) solution is heated to 40 to 80 t, and the diisocyanate compound (n) is added dropwise thereto to cause the two to react to produce the epoxy resin for paint of the present invention.

Both reactions must be carried out at a ratio such that the equivalent ratio of the hydroxyl group of the reaction product (I) to the isocyanate group of the diisocyanate compound (II) is (10.8 to 1.2). If the isocyanate group equivalent is smaller than the above range, it will be difficult to form a polymer resin, and the coating performance will deteriorate.
On the other hand, if it is too large, the varnish viscosity increases, the solubility in high flash point solvents decreases, and the storage stability deteriorates, which is not preferable.

The epoxy resin for paints of the present invention is produced by the method described above, and in addition, a high flash point solvent or a high flash point solvent is used as a main component, and if necessary, a curing agent, a low flash point solvent, a coloring pigment, It is made into a paint by blending extender pigments, anti-rust pigments, modified resins, additives, etc.

The high flash point solvent is mineral spirit, ...
Aliphatic hydrocarbons such as M, &P, Natsuta: carbon number 9
~11 mixed aromatic hydrocarbons, such as Tsurpetz 10
0, Tsurpez 150, Tsurpez 200 [manufactured by Exxon Chemical Co., Ltd.], Pegasol R=100, Vegasol R-150 [manufactured by Mobil Oil Co., Ltd.], Supersol 1500 [manufactured by Mitsubishi Oil Corporation], Swasol 100 [manufactured by Maruzen Petrochemical Co., Ltd.], Ibusol 100 [manufactured by Maruzen Petrochemical Co., Ltd.]
manufactured by Idemitsu Petrochemical Co., Ltd.).

As the curing agent, those conventionally used as curing agents for epoxy resins can be used without particular limitation, such as triethylenetetramine, metaxylene diamine,
Typical examples include amines such as diaminodiphenylmethane and isophorone diamine, and polyamide resins.

Typical examples of the low flash point solvent include toluene, xylene, methyl ethyl, methyl isobutyl ketone, and ethyl acetate, which are used in small amounts in combination with the high flash point solvent.

<Effects> The epoxy resin for paints of the present invention is soluble or stably dispersed in a solvent with a high flash point, high boiling point, and low pollution, so it can be made into a paint using the solvent, and therefore it is suitable for the painting environment. It has good painting workability, does not dissolve or swell the old paint film even if it is repainted to repair the old paint film, and provides a paint film with excellent corrosion resistance, adhesion, flexibility, etc., compared to conventional epoxy. It is possible to exhibit various excellent coating film performances that could not be achieved with resin paints.

Hereinafter, the present invention will be explained in more detail with reference to Examples. In the examples, "parts" and "%" are based on weight.

Examples 1 to 13 and Comparative Examples 1 to 5 Into a reactor equipped with a thermometer, a stirrer, and a reflux condenser, ``Tsurpetz 100J (amount to give 70% as nonvolatile content),
Epoxy resin, alkylphenol, and aliphatic monocarboxylic acid were charged in the proportions shown in Table 1, the temperature was raised to about 110°C, and while stirring, 0.0% potassium hydroxide was added to the total amount of resin.
01%, then heated to 150°C, and kept at the same temperature for 3
After confirming that the acid value was 2 mgKOH/g or less and the presence of free alkylphenol was no longer observed, the mixture was cooled to 40°C. At the same temperature, diisocyanate compounds were added dropwise in the proportions shown in Table 1, and the reaction was allowed to occur until no absorption of -NC○ was observed using an infrared spectrophotometer. Epoxy resin for paints (70% "Tsurupets 100" solution)
Manufactured varnish.

The properties of the obtained epoxy resin were as shown in Table 1.

Note 1) Product name manufactured by Tobu Kasei Co., Ltd.: Epoxy equivalent 184-194 Note 2) Product name manufactured by Dainippon Ink & Chemicals Co., Ltd.: Epoxy equivalent 165-185 Note 3) Product name manufactured by Tobu Kasei Co., Ltd.: Epoxy equivalent 450-500 Note 4 ) Average epoxy equivalent of the mixture 200 Note 5) Average epoxy equivalent of the mixture 270 Note 6) (Total equivalent of hydroxyl group of alkylphenol and carboxyl group of aliphatic monocarboxylic acid) / (Epoxy equivalent of epoxy resin) Note 7)
(Equivalent of hydroxyl group of alkylphenol)/(Equivalent of carboxyl group of aliphatic monocarboxylic acid) Note 8) (Equivalent of hydroxyl group of reaction product)/(Equivalent of isocyanate group of diisocyanate compound)) Storage stability was good.

On the other hand, the ratio of (hydroxyl group equivalent of reaction product (I)) to isocyanate group equivalent of the badisocyanate compound is 1/1.
The varnishes of Comparative Example 4, which is 5, and Comparative Example 5, which uses an epoxy resin in which the epoxy equivalent of epoxy resin (a) exceeds 250, both have poor storage stability and cannot be practically used as paints. there were.

Next, the varnishes obtained in Examples 1 to 13 and Comparative Examples 1 to 5 were tested for performance as paints.

Reference Examples A-M and Reference Comparative Examples N-R Examples 1 to 13
The components shown in Table 2 were added to the varnishes obtained in Comparative Examples 1 to 5 to prepare paints.

The condition, adhesion, and corrosion resistance of the resulting paint were tested, and the results are shown in the lower column of Table 2.

As is clear from Table 1, Examples 1 to 13, which are the epoxy resin varnishes of the present invention, have good transparency (that is, they are well melted on "Tsurupets" 00) (9) Note 10) Note) polyamide amine [“New Mite #515” manufactured by Cage Co., Ltd., product name, amine value 240] For all of the reference examples and reference comparative examples (varnish epoxy per 3
1) It was blended so that the ratio of (curing agent amine equivalent) was 110.8.

The viscosity of the paint (excluding hardener) is 95±5K using a 3-roll mill.
[After adjusting to I (25°C), leave it at 20°C for 7 days,
The condition of the paint was observed.

○: No abnormality, △: Slight varnish separation, ×: Varnish separation and significant thickening. Apply to a mild steel plate with air spray to a dry film thickness of 100μ, dry at 20°C for 7 days, and apply cellophane with a grain pattern. A Qi 7' test (25 stitches at 2 mm intervals) was conducted.

○; 25/25 (number of remaining eyes/number of tests) △: 13-24
/25,
A salt spray test (400 hours) was conducted in accordance with JIS K 5400-7.8.

○: No abnormality, △: Some blistering and rust occurrence, ×: Significant blistering and rust occurrence. The paint stability was also good, and the resulting paint film had excellent adhesion and corrosion resistance.

On the other hand, reference comparative examples N and O in which the ratio of (total equivalent of hydroxyl group of alkylphenol and carboxyl group of aliphatic monocarboxylic acid)/(epoxy equivalent of epoxy resin) was deviated from 1/(1,8 to 2.5) and Reference Comparative Example P in which the ratio of (hydroxyl group equivalent of alkylphenol)/(carboxyl group equivalent of aliphatic monocarboxylic acid) was 1/4, both had poor corrosion resistance.

In addition, the paints of Reference Examples A-M were applied to an old salt rubber-based paint film (exposed outdoors for 1 year) and an old T-rukyd resin paint film (1 year exposed outdoors).
When applied to each item (exposed outdoors for 9 years) and observed after 5 hours, no abnormalities were observed.

Similarly, when a commercially available epoxy resin paint using a strong solvent was applied, the old paint film was lifted.

Claims (1)

[Scope of Claims] (a) an epoxy resin having two or more epoxy groups in one molecule and having an average epoxy equivalent of about 250 or less; (b) an alkylphenol; and (c) an aliphatic monocarboxylic acid. and the ratio of the total equivalent of the hydroxyl group in the alkylphenol (b) and the carboxyl group in the aliphatic monocarboxylic acid (c) to the equivalent of the epoxy group in the epoxy resin (a) is (1:1 .8 to 2.5), and the ratio of the equivalent of the hydroxyl group in the alkylphenol (b) to the equivalent of the carboxyl group in the aliphatic monocarboxylic acid (c) is (1:0
The reaction product (
I), the diisocyanate compound (II) is added to the reaction product (
The ratio of the equivalent weight of hydroxyl groups in I) to the equivalent weight of isocyanate groups in the diisocyanate (II) is (1:0.8-1.
2) An epoxy resin for paints obtained by reacting at the following ratio.