JP3371476B2 - Polyol and resin composition for coating - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polyol having a low melt viscosity and excellent coating film strength and water resistance as a coating resin.

[0002]

2. Description of the Related Art Conventionally, as a curable coating material, for example, a resin composition having an epoxy polyol resin obtained by modifying a bisphenol type epoxy resin with a higher fatty acid as a main component and a polyisocyanate as a curing agent has been widely used. .

This utilizes the fact that the hydroxyl group in the epoxy polyol resin and the isocyanate group in the polyisocyanate compound react easily, and is utilized particularly for curing at a low temperature. Therefore, it is necessary to increase the number of hydroxyl groups in one molecule in order to obtain a strong cured product in the curing system of epoxy polyol and isocyanate.

However, the above epoxy polyol resin is
Since it contains many hydroxyl groups in its skeleton, the viscosity of the resin is high, the solubility in organic solvents is insufficient, and it is necessary to use a large amount of solvent at the time of use, resulting in a large film thickness and toughness. It was difficult to obtain a coating film.

Conventionally, there has been known a method of reducing the viscosity by introducing a polyalkylene oxide skeleton into the skeleton of the epoxy polyol resin in order to reduce the viscosity of the epoxy polyol resin and increase the solid content.

[0006]

However, the resin in which the polyalkylene oxide skeleton is introduced into the skeleton of the epoxy polyol resin has a low resin viscosity and improves the solubility in an organic solvent, but the strength of the coating film upon curing is high. There was a problem that the water resistance was insufficient.

The problem to be solved by the present invention is to provide a polyol having a low viscosity and good compatibility, and a coating resin composition having excellent water resistance and adhesiveness.

[0008]

Means for Solving the Problems As a result of intensive studies made by the present inventors, a polyol resin having a weight average molecular weight of 500 to 1,500 represented by the following general formula (1) solves the above problems. The inventors have found what can be done and have completed the present invention.

A polyol represented by the general formula (1) having a weight average molecular weight of 500 to 1,500,

[Chemical 2] (In the general formula (1), R is an alkyl group having 8 to 22 carbon atoms, an alkene group or a hydroxylalkyl group, n is an integer of 1 to 5. A is CmH2m + 1, and m is an integer of 0 to 5. And a polyol (A) and a curing agent (B) as essential components.

When the epoxy polyol resin of the present invention has a weight average molecular weight of less than 500, the strength and water resistance of the coating film formed as a resin composition are poor, and the weight average molecular weight is 1,500. If it exceeds, the resin viscosity increases remarkably, and it becomes impossible to obtain a resin having a high solid content concentration.
Among them, the weight average molecular weight is 800 to 1,5 from the viewpoint of excellent balance between coating strength or water resistance and resin viscosity.
It is preferably 00.

Further, as an example of the following general formula (1),
Phenol novolac type epoxy resin, cresol novolac type epoxy resin, bisphenol A novolac type epoxy resin, 2,6-xylenol novolac epoxy resin, 2-naphthol novolac type epoxy resin,
Using a novolac type epoxy resin such as 1,6-dihydroxynaphthalene novolac type epoxy resin as a starting material,
The thing obtained by making a long-chain aliphatic carboxylic acid react is mentioned.

[0012]

[Chemical 2] (In the general formula (1), R is an alkyl group having 8 to 22 carbon atoms, an alkene group or a hydroxylalkyl group, n is an integer of 1 to 5. A is CmH2m + 1, and m is an integer of 0 to 5. Represents)

The novolac type epoxy resin is a polyhydric phenol obtained by condensation reaction of phenols such as phenol, cresol, 2,6-xylenol, resorcin, 2-hydroxynaphthalene, 1,6-dihydroxynaphthalene and bisphenol A with formalin. It is obtained by subjecting a compound and epihalohydrin to a condensation reaction. The condensation reaction between polyhydric phenols and epihalohydrin can be carried out by a known general-purpose method, and examples thereof include the following reactions.

The above-mentioned phenol novolac type epoxy resin which is a raw material of the polyol of the present invention includes phenol, cresol, 2,6-xylenol, resorcin, 2-hydroxynaphthalene, 1,6-dihydroxynaphthalene,
It is obtained by subjecting polyhalogenated phenols obtained by subjecting phenols such as bicphenol A to a condensation reaction with formalin to epihalohydrin. The condensation reaction between polyhydric phenols and epihalohydrin can be carried out by a known general-purpose method, and examples thereof include the following reactions.

First, 0.5 to 15 equivalents, preferably 3 to 10 equivalents, of epihalohydrin are added and dissolved with respect to the hydroxyl groups in the polyhydric phenols, among which the effect of reducing the resin viscosity is excellent. 0.8 to 1.2 equivalents of a 10 to 50% NaOH aqueous solution with respect to the hydroxyl groups in the phenols is added dropwise at a temperature of 50 to 80 ° C. for 3 to 5 hours.
After the dropping, stirring is continued for about 0.5 to 2 hours at that temperature, and after standing, the lower layer saline solution is discarded. Then, excess epihalohydrin is recovered by distillation to obtain a crude resin. Toluene,
An organic resin such as MIBK is added, and the desired resin can be obtained through the steps of washing with water, dehydration, filtration, and desolvation.

The epihalohydrin used here is
Epichlorohydrin is the most common, but epiiodohydrin, epibromhydrin, β-methylepichlorohydrin and the like can also be used.

As the long-chain aliphatic carboxylic acid, a higher fatty acid having 8 to 22 carbon atoms is indispensable from the viewpoint of excellent viscosity-reducing effect and strength or water resistance of the coating film.

The long-chain aliphatic carboxylic acid having 8 to 22 carbon atoms may be either a saturated carboxylic acid or an unsaturated carboxylic acid, and may have a hydroxyl group in the hydrocarbon chain. Specific examples of these include stearic acid, oleic acid, palmitic acid, ricinooleic acid, dioxystearic acid, soybean oil fatty acid, castor oil fatty acid,
Examples include sunflower oil fatty acid. Among them, unsaturated carboxylic acids having a hydroxyl group in the hydrocarbon chain are preferable from the viewpoint of more excellent coating film strength, and specific examples thereof include ricinooleic acid, dioxystearic acid, castor oil fatty acid and the like.

As described above, the polyol of the present invention can be obtained by reacting a long-chain aliphatic carboxylic acid with the epoxy group of a phenol novolac type epoxy resin. The conditions of the esterification reaction are not particularly limited. But not
The above epoxy resin and the above aliphatic carboxylic acid having 8 to 22 carbon atoms are mixed in an equivalent amount or in such a manner that the carboxyl group is slightly excessive, and then 80 to 23 in the presence of a basic catalyst.
It is preferable to heat to a temperature of 0 ° C. to proceed.

Examples of the catalyst used here include alkali metal hydroxides such as sodium hydroxide and lithium hydroxide, triethylamine, tributylamine, pyridine,
Tertiary amines such as dimethylbenzylamine, imidazoles such as 2-ethyl-4-methylimidazole, quaternary ammonium salts such as triethylbenzylammonium chloride, tetramethylammonium chloride, tetrabutylphosphonium chloride, ethyltriphenyl Examples thereof include phosphonium salts such as phosphonium iodide and phosphines such as triphenylphosphine.

The coating resin composition of the present invention contains the above-mentioned polyol resin (A) and a curing agent (B) as an essential component. The curing agent (B) is not particularly limited as long as it can react with a hydroxyl group, and examples thereof include an isocyanate compound, a blocked isocyanate compound, a melamine resin, and a resol type phenol resin. Isocyanate compounds are preferred for low temperature curing .

Examples of the isocyanate compound include toluene diisocyanate, xylylene diisocyanate, diphenylmethane diisocyanate, hexamethylene diisocyanate, polyphenylene polymethylene polyisocyanate, and 3 mol adduct of trimethylolpropane with toluene diisocyanate, and a high molecular weight polyisocyanate obtained from them. Etc. Here, when polyphenylene polymethylene polyisocyanate is used as the curing agent, the composition can be prepared without using a solvent.

The mixing ratio of the isocyanate compound is such that the mixing ratio of the hydroxyl group equivalent and the isocyanate group equivalent in the polyether polyol resin is 0.4 to 1.2, preferably 0.6.
A ratio of about 1.0 is preferable.

In the coating composition of the present invention, an organic solvent can be used. However, when polyphenylene polymethylene polyisocyanate is used as a curing agent as described above, the composition can be prepared without using a solvent. can do.

Further, in the coating composition of the present invention,
Further, the polyol (A) may be used in combination with another polyol or a polymer compound capable of reacting with the above curing agent in an amount of less than 50% by weight of the total amount of the polyol (A).

The coating resin composition of the present invention may further contain a filler such as a bituminous substance. Bituminous substances include coal tar, coal tar pitch, swollen carbonaceous material,
Examples include asphalt.

Further, a substitute for the bituminous substance may be used as the extender. Examples of the substitutes include various ones. For example, aromatic oil resins, petroleum resins, and petroleum-based or coal-based high-boiling neutral oils generally used as diluents can be used.

The above bituminous substances and their substitutes may be used alone or in combination, and the total amount thereof is the polyol resin (A).
It is preferable that the weight is 0.5 to 2.0 times.

If desired, various curing catalysts, fillers, diluents, dehydrating agents, resins, etc. may be added to the composition of the present invention.

[0030]

The present invention will be further described below with reference to examples.
Various tests were evaluated according to the following methods. As a sample for evaluation of hardness, flexibility, impact resistance, salt water resistance and corrosion resistance, a metal plate obtained by drying each resin composition at room temperature for 7 days was used.

(Flexibility) JIS K-5400 (6.1)
According to 6). (Impact resistance) Based on JIS K-5400. (Load 500g) (Salt water resistance) Immersed in 5% salt water for 1 month and visually evaluated according to the following criteria.

◯: No discoloration, wrinkles or blisters. Δ: discolored, no wrinkles and no blisters ×: Discoloration, wrinkles, swelling.

(Corrosion resistance) 5% salt water was sprayed for 500 hours,
Then, a notch was made with a width of 8 mm, and the rust width from the notch line and the peel width when peeled with a cellophane tape were evaluated.

[0034]

Example 2 Bisphenol F type epoxy resin EPICLON 830 (Dainippon Ink and Chemicals, Inc., epoxy equivalent 170) 17
After mixing 0 part by weight and 300 parts by weight of soybean oil fatty acid and adding 2 parts by weight of tributylamine as a catalyst, 160 ° C
When the acid value becomes 1 or less, the mixture is cooled to 140 ° C., 52 parts by weight of xylene is added and dissolved to obtain a solid content of 90.
% Polyether polyol resin was obtained. The polyether polyol resin had a solid content hydroxyl group equivalent of 330, a solution viscosity of 2,500 cps. And a weight average molecular weight of 693. A chart of the infrared absorption spectrum of the obtained polyol is shown in FIG. Then, a coating resin composition was obtained in accordance with the formulation shown in Table 2 and various tests were conducted. The results are shown in Table 2.

Example 3 Phenolic novolac type epoxy resin EPICLON N-7
40 (Dainippon Ink and Chemicals, Inc., epoxy equivalent 18)
0) 180 parts by weight and 300 parts by weight of castor oil fatty acid were mixed, and 2 parts by weight of tributylamine was added as a catalyst.
When heated to 160 ° C and the acid value becomes 1 or less, 14
After cooling to 0 ° C., 85 parts by weight of xylene was added and dissolved to obtain a polyether polyol resin having a solid content of 85%. The polyether polyol resin has a solid content hydroxyl group equivalent of 310, a solution viscosity of 4,500 cps., And a weight average molecular weight of 775.
Met. Then, a coating resin composition was obtained in accordance with the formulation shown in Table 2 and various tests were conducted. The results are shown in Table 2.

Example 4 Cresol novolac type epoxy resin EPICLON N-6
65 (Dainippon Ink and Chemicals, Inc., epoxy equivalent 21
0) 210 parts by weight and 295 parts by weight of sour oil fatty acid were mixed, 2 parts by weight of tributylamine was added as a catalyst, then heated to 160 ° C., cooled to 140 ° C. when the acid value became 1 or less, and xylene was added. 89 parts by weight was added and dissolved to obtain a polyol resin having a solid content of 90%. The polyether polyol resin had a solid content hydroxyl group equivalent of 330, a solution viscosity of 5,000 cps. And a weight average molecular weight of 912. Then, a coating resin composition was obtained in accordance with the formulation shown in Table 2 and various tests were conducted. The results are shown in Table 2.

Example 5 Cresol novolac type epoxy resin EPICLON N-6
73 (Dainippon Ink and Chemicals, Inc., epoxy equivalent 21)
0) 210 parts by weight and 295 parts by weight of sunflower oil fatty acid were mixed, 2 parts by weight of tributylamine was added as a catalyst, and the mixture was heated to 160 ° C. and cooled to 140 ° C. when the acid value became 1 or less. After mixing, 89 parts by weight of xylene was added and dissolved to obtain a polyether polyol resin having a solid content of 85%. The polyether polyol resin had a solid content hydroxyl group equivalent of 350, a solution viscosity of 5,500 cps. And a weight average molecular weight of 1,060. Met. Then, a coating resin composition was obtained in accordance with the formulation shown in Table 2 and various tests were conducted. The results are shown in Table 2.

COMPARATIVE EXAMPLE 1 300 parts by weight of soybean oil fatty acid was mixed with 140 parts by weight of glycidyl ether of trimethylolpropane (epoxy equivalent: 140), 2 parts by weight of tributylamine was added as a catalyst, and the mixture was heated to 160 ° C. to give an acid value. When it became 1 or less, it was cooled to 140 ° C., 52 parts by weight of xylene was added and dissolved to obtain a polyether polyol resin having a solid content of 90%. The polyether polyol resin had a solid content hydroxyl group equivalent of 280 and a solution viscosity of 4,500 cps. Then, a coating resin composition was obtained according to the formulation shown in Table 2 and various tests were conducted. The results are shown in Table 2.

Comparative Example 2 300 parts by weight of soybean oil fatty acid was mixed with 300 parts by weight of glycidyl ether (epoxy equivalent of 300) of 3 mol adduct of ethylene oxide of bisphenol A, and 2 parts by weight of tributylamine was added as a catalyst. Heat to ℃, cool to 140 ℃ when the acid value becomes 1 or less, add 105 parts by weight of xylene and dissolve to solid content of 85%
To obtain a polyol resin. The polyol had a solid content hydroxyl group equivalent of 3000 and a solution viscosity of 4,500 cps. Then, a coating resin composition was obtained in accordance with the formulation shown in Table 2 and various tests were conducted. The results are shown in Table 2.

Comparative Example 3 Solid content of 100 was obtained in the same manner as in Example 1 except that 150 parts by weight of glycidyl ether of neopentyl glycol (epoxy equivalent of 150) and 305 parts by weight of castor oil fatty acid were used.
% Polyol was obtained. The obtained polyol had a hydroxyl equivalent of 230 and a melt viscosity of 3,100 cps. Then, a coating resin composition was obtained in accordance with the formulation shown in Table 2 and various tests were conducted. The results are shown in Table 2.

Examples 2, 3, 4 and Comparative Examples 1, 2, 3
Table 1 shows the viscosity of the solution (25 ° C.).

[0043]

[Table 1]

[0044]

[Table 2]

[0045]

[Table 3]

[0046]

According to the present invention, it is possible to provide a polyol having a low viscosity and good compatibility, and a coating resin composition having excellent corrosion resistance and adhesion.

Therefore, the coating resin composition of the present invention is extremely useful as a coating material and the like.

[Brief description of drawings]

FIG. 1 is a chart diagram of an infrared absorption spectrum of the polyol of the present invention obtained in Example 2.

Front page continuation (58) Fields surveyed (Int.Cl. ⁷ , DB name) C08G 59/16 C08G 18/58 C09D 175/04

Claims (3)

(57) [Claims] 1. A weight average molecule represented by the general formula (1).
Polyol in an amount of 500 to 1,500 . [Chemical 1] (In the general formula (1), R is an alkyl group having 8 to 22 carbon atoms, an alkene group or a hydroxylalkyl group, and n is
It represents an integer of 1 to 5. A is CmH2m + 1 and m is 0-5
Represents a number. ) 2. A weight average molecule represented by the general formula (1).
A coating resin composition comprising a polyol having an amount of 500 to 1,500 and a curing agent (B) as essential components. 3. The composition according to claim 2, wherein the curing agent (B) is an isocyanate compound.