JPH072930B2 - Method of forming cured coating film - Google Patents

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a novel and useful epoxy resin composition, and more specifically, it comprises a polyfunctional epoxy resin obtained by using a specific polymerizing agent as an essential resin component. It relates to a resin composition.

[0002]

2. Description of the Related Art Epoxy resins are excellent in adhesion and adhesion, water resistance, chemical resistance, electrical insulation, heat resistance, dimensional stability, etc. when combined with various curing agents, and thus paints, It is an important industrial material that is used in a wide range of applications such as adhesives, electricity, and civil engineering, so to speak, supporting modern industry.

By the way, such epoxy resin is generally
Various epoxy resins obtained from diphenols which should be called main constituents of epoxy resins represented by bisphenol-A, and epoxy group-supplying compounds represented by epichlorohydrin, polyamine compounds, phenolic resins, acid anhydrides, etc. It has been used for many applications under various curing conditions by using a curing agent represented by as a main component and further combining a third substance represented by a pigment such as talc if necessary. Said curing methods are roughly classified into so-called room-temperature dry-curing type in which curing is performed by simply leaving the natural phenomenon itself as it is without any intervention of so-called external factors such as heating, and heat and pressure. External factors that are physical or chemical means such as Promote 燥, about to be divided into two systems of a forced drying-curing of obtaining the desired target product.

Among them, in the forced dry curing type, physical factors applied from the outside are maintained under a certain condition to overcome a geographical or climatic difference, so that a stable condition is always obtained. It can be said that setting dry-curing conditions is not so difficult, but rather is relatively easy.

On the other hand, if it is a room-temperature dry-curing type, it is almost impossible to expect that the geographical or meteorological conditions are constant, and the so-called natural conditions are the dry-curing conditions as they are and the temperature, humidity and Many factors, such as airflow, are different each time, making it difficult to control artificially.

As described above, although the epoxy resin is actually dried and cured by these two dry curing methods, when it is necessary to perform it under natural dry curing conditions, coating, adhesion, electrical application, Widely used for civil engineering, etc.
Most of the "heavy anticorrosion paints" based on epoxy resins used as anticorrosion paints, especially for large steel constructions, require action under natural dry curing conditions.

In these fields, there is a method of painting and assembling the necessary steel materials, for example, as in the case of building ships, or a method of painting after assembling each step. The coating method is also set, and in particular, such steel materials are large,
It can be said that there is no method other than using natural phenomena as a dry-curing condition after painting in terms of economics in the case of irregular production of the same product in large quantities. .

[0008] Such an application field in which the air-drying and curing method is unavoidably adopted is not limited to the above-mentioned use for ships, but also for paints and adhesives for steel pipes, bridges, large vehicles, aircraft or buildings, roads, etc. It is extremely diverse for civil engineering applications such as repairs.

[0009]

However, such an epoxy resin itself has various excellent properties as described above, and is used in combination with various curing agents. Among them, the natural dry curing method is used. In the case of use by, although most of them are used in combination with an amine-based curing agent from the viewpoint of obtaining excellent coating film performance, the greatest drawback of such a use method is that the room temperature curability is poor, As a result, there is a problem that the hardness of the obtained coating film is lowered.

On the other hand, in order to improve the room temperature curing property, use of a curing accelerator, use of a thiochol type curing agent capable of reacting at low temperature, use of an ester type epoxy resin,
Alternatively, although methods such as the use of an epoxy-urethane system are used, the use of these methods impairs the excellent performance of the epoxy-amine system such as adhesion, corrosion resistance and water resistance, which is an unfavorable result. Was invited.

From such an actual condition, it is excellent in room temperature curing property and has excellent performance of epoxy-amine type.
There has been a strong demand for establishment of a method for forming a coating film having a remarkably excellent coating film hardness.

[0012]

The inventors of the present invention have conducted many years of research to meet these long-standing demands, and as a result, a coating film which exhibits excellent hardness when naturally dried and cured. The present invention has been completed by finding a method of forming the above.

That is, the present invention has an epoxy resin (a-1) having two glycidyl ether groups derived from a diphenol compound having a bifunctional phenolic hydroxyl group in the same molecule and having an epoxy equivalent of 100 to 800. )
In addition, a novolak resin (a-2) having an average number of functional groups in one molecule of 2.3 to 6 is added to one epoxy group in the epoxy resin (a-1) to give a polymerizing agent (a-2 In the above), a polyfunctional epoxy resin (A) having an epoxy equivalent of 200 to 2,000 obtained by reacting at a use ratio of 0.5 or less phenolic hydroxyl groups, and a curing agent (B) for an amine-based epoxy resin. A cured coating film having excellent room temperature curability and coating hardness, which is obtained by applying an epoxy resin composition containing and as essential components to a material and naturally drying and curing at room temperature higher than 10 ° C. Above all, as the above novolak resin (a-2), a phenol-novolak resin is used, a resin obtained by modification with a novolak resin derived from a diphenol compound is used, or a xylene resin is used. Phenol, in which it is possible to use a polyhydric phenol such as a resin obtained by denaturing a substituted phenol or phenol-novolak resin.

Here, the polyfunctional epoxy resin (A) means bisphenol-A having an epoxy equivalent of 100 to 800, more preferably 200 to 700.
Alternatively, the epoxy resin (a-1) having two glycidyl ether groups derived from a diphenol compound having a bifunctional phenolic hydroxyl group represented by bisphenol-F in the same molecule has an average of 2. Polyphenols having 3 to 6 phenolic hydroxyl groups, that is, a novolak resin (a-2) having an average number of functional groups of 2.3 to 6 in one molecule is a novolak resin (a- The epoxy equivalent obtained by reacting 2) at a ratio of 0.5 or less phenolic hydroxyl groups is 200 to.
2,000, more preferably an epoxy equivalent of 220-
1,800 is a resin. The above-mentioned diphenol compound is a general formula corresponding to bisphenol-A, bisphenol F or isomers thereof.

[0015]

[Chemical 1]

(Wherein R ₁ and R ₂ in the formula represent a hydrogen atom or a residue such as an alkyl group or an alkenyl group); and the benzene nucleus in the general formula [I] is chlorine. Or dihydroxyphenyl alkanes substituted with a halogen atom such as bromine or an alkyl group; General formula

[0017]

[Chemical 2]

The term refers to all compounds having two phenolic hydroxyl groups in the same molecule, including dihydroxybenzenes represented by the formula (1) and their nuclear alkyl-substituted or nuclear halogen-substituted compounds.

These diphenol compounds and an epoxy group-providing substance such as epichlorohydrin, epibromhydrin or methyl epichlorohydrin are identified by a known method as described in, for example, "Epoxy Resin" published by Shokoido. A so-called diglycidyl ether type epoxy resin (a-1) having approximately two glycidyl ether groups in the molecule is obtained.

Next, the above-mentioned novolac resin (a-2)
Is a general formula obtained from a monophenol compound such as phenol and / or an alkylphenol and formaldehyde, or a diphenol compound and formaldehyde.

[0021]

[Chemical 3]

(In the formula, R ₃ , R ₄ and R ₅ are each a hydrogen atom or methyl, ethyl, n-butyl,
represents an alkyl group or an alkenyl group such as t-butyl, octyl or nonyl group, and n is 0.3 to
It is a rational number of 4. ), And then obtained by modifying these based on xylene resin with phenol, substituted phenol or phenol novolac resin, “Plastics”, Volume 33, No. 7, published by the Industrial Research Committee. And so-called modified phenolic resins such as those described in No. 8 and the like, and have an average number of functional groups of 2.3 to 6 as described above.
Resins within the range are included.

Here, for example, the above-mentioned general formula [II
I]] means that n = 0.3 to 4,
The phenol / novolak resin itself has n = 0,
It should be noted that it is often obtained as a mixture of the compounds 1, 2, ..., and is referred to as an average value of the mixture.

Therefore, the polyfunctional epoxy resin (A) used in the present invention is the diglycidyl ether type epoxy resin (a-1) and the novolac resin (a).
-2), but in that case (a
The use ratio of -1) and (a-2) does not always have to be in any range, and one epoxy group in (a-1) must be used for (a-2). It is essential that the number of phenolic hydroxyl groups is 0.5 or less,
In addition, since the use ratio is limited based on the number of n in the above-mentioned general formula [III] and the phenolic hydroxyl group present in the molecule, a use range that does not cause gelation is selected. It should be necessary.

As described above, the epoxy resin (a-1) and the novolac (a-) are used in the above-mentioned limited use ratios.
2) and the desired polyfunctional epoxy resin (A) can be obtained by known methods such as those described in JP-A-48-83199 and "Epoxy Resin" mentioned above.

More specifically, the curability at room temperature higher than 10 ° C., which is an important constituent factor in the present invention, depends on the number of functional groups of the polyfunctional epoxy resin (A) thus obtained, and therefore Epoxy resin (a-1)
It can be said that the combination of and the novolak resin (a-2) is the most important factor.

That is, the polyfunctional epoxy resin (A)
By bringing the number of functional groups of (1) to 2 as close as possible, the low-temperature curable factor will be destroyed as much as possible. On the basis of such knowledge, polyfunctionality for obtaining practical room temperature curability that meets the purpose of the present invention refers to an average number of functional groups of 2.3 or more, and in terms of workability and the like. Is an average number of functional groups of 10 or less.

On the other hand, the above-mentioned curing agent (B) for epoxy resin refers to a substance capable of reacting with the above-mentioned polyfunctional epoxy resin to dry and harden the resin. As the compound, an amino group (imino group) -containing compound represented by polyamines or a derivative thereof can be used. Among them, typical examples include aliphatic amines such as triethylenetetramine; aromatic compounds such as diaminodiphenylmethane. Group amines;
Alicyclic amines such as "Laromin C-260" [bis (4-amino-3-methyl-cyclohexyl) -methane manufactured by BAS, West Germany], amine compounds such as isophoronediamine or xylylenediamine, An amide compound or a polyamidoamine compound obtained from such an amine compound and a fatty acid or a dimer fatty acid, or an amide / adduct amine compound or an amine / adduct compound which is a precocondensation product of an amine compound and an epoxy resin. There are known and conventional amine-based curing agents such as those described in “Epoxy Resin” above.

The polyfunctional epoxy resin (A) and the curing agent for epoxy resin (B) as described above are used as essential components at 10 ° C.
By performing natural room temperature dry curing at a higher room temperature, required strength such as coating film hardness, handling property, water resistance and corrosion resistance, solvent resistance, etc. can be obtained earlier.

The composition used in the present invention may further contain, if necessary, a curing accelerator, a solvent, a diluent, an organic compound such as bitumen or petroleum resin, glass, carbon, titanium, talc, Of course, inorganic materials such as pigments such as silica can be included.

[0031]

EXAMPLES Next, the present invention will be described in detail with reference to Reference Examples, Examples and Comparative Examples. All parts and% are based on weight unless otherwise specified.

Reference Examples 1 to 5 [Preparation Examples of Polyphenols Novolak Resin (B)] Monophenol compounds as shown in Table 1 and 37%
Use formalin in a specified amount, add 0.3 g of hydrochloric acid and react at 80 ° C for 4 hours, then neutralize with 10% sodium hydroxide aqueous solution until pH becomes 7.5. Then, excess monophenol compound was distilled with water vapor until it could not be substantially detected to obtain various phenol / novolak resins having the property values shown in the table.

[0033]

[Table 1]

Reference Example 6 [Preparation Example of Polyfunctional Epoxy Resin (A)] "Epiclon 850" was placed in a 1-liter four-necked flask equipped with a stirrer, a nitrogen introducing tube, a thermometer and a condenser.
[Bisphenol-manufactured by Dainippon Ink and Chemicals, Inc.
190 g of an epoxy resin having an epoxy equivalent of 190 obtained from A and epichlorohydrin] and 22.1 g of a phenol resin (a-2-1), that is, an epoxy group 1
It is charged at a ratio of 0.18 phenolic hydroxyl groups to 0.4 g of 1% sodium hydroxide aqueous solution.
Was added and reacted at 140 ° C. for 5 hours, and then 90.9 g of methyl isobutyl ketone was added to obtain a target resin (A). This is a resin solution having an epoxy equivalent of 260 and a nonvolatile content of 70%, which will be abbreviated as resin (A-1) below.

Reference Example 7 (Same as above) In the same manner as in Reference Example 6, 170 g of "Epiclone 83
0 "(an epoxy resin having an epoxy equivalent of 170 obtained from bisphenol-F and epichlorohydrin manufactured by Doujinsha Co., Ltd.) and 22.1 g of a phenol resin (a-2-
2), that is, at a ratio of 0.21 phenolic hydroxyl groups to 1 epoxy group, 0.4 g of a 1% aqueous sodium hydroxide solution was added, and the mixture was heated at 140 ° C. for 4 hours.
The reaction is allowed to proceed for 82 hours and then methyl isobutyl ketone 82.
3 g was added to obtain the target resin (A). This is a resin solution having an epoxy equivalent of 243 and a nonvolatile content of 69.8%, which is hereinafter abbreviated as resin (A-2).

Reference Example 8 (same as above) Instead of the polyhydric phenol (a-2-2), 33.7 g
Except that the phenol resin (a-2-3) was used in a ratio of 0.21 phenolic hydroxyl groups to 1 epoxy group, and 87.3 g of methyl isobutyl ketone was used. Was obtained in the same manner as in Reference Example 6 to obtain a solution having a nonvolatile content of 70.5% of the target resin (A) having an epoxy equivalent of 300. Hereinafter, this is a resin (A-
It is abbreviated as 3).

Reference Example 9 (Same as above) Instead of the polyhydric phenol (a-2-3), the same amount of the phenol resin (a-2-4) was used, that is, one epoxy group and phenolic hydroxyl group of 0. The nonvolatile content of the target resin (A) having an epoxy equivalent of 238 is 7 in the same manner as in Reference Example 7 except that the amount is changed to 21.
A 0.8% solution was obtained. Hereinafter, this is a resin (A-4)
Is abbreviated.

Reference Example 10 (Same as above) In the same manner as in Reference Example 6, 260 g of "Epiclon 86" was used.
0 "(an epoxy resin having an epoxy equivalent of 260 obtained from bisphenol-A and epichlorohydrin manufactured by Doujinsha Co., Ltd.) and 41.4 g of a phenol resin (a-2-
1), that is, a ratio of 0.35 phenolic hydroxyl groups to 1 epoxy group, 0.6 g of a 1% aqueous sodium hydroxide solution was added, and the mixture was reacted at 160 ° C. for 5 hours and then methyl. Isobutyl ketone 100.
5 g and 100.3 g of xylene were added to obtain a solution having a nonvolatile content of 60.5% of the target resin (A) having an epoxy equivalent of 465. Hereinafter, this is abbreviated as resin (A-5).

Reference Example 11 (same as above) Instead of the polyhydric phenol (a-2-1), the same amount of the phenol resin (a-2-2) was used, that is, one epoxy group and one phenolic hydroxyl group. The non-volatile content of the target resin (A) having an epoxy equivalent of 470 was 5 in the same manner as in Reference Example 10 except that the content was changed to 39.
A 9.8% solution was obtained. Hereinafter, this is a resin (A-6)
Is abbreviated.

Reference Example 12 (same as above) In place of the polyhydric phenol (a-2-1), the same amount of the phenol resin (a-2-5) was used, that is, one epoxy group and one phenolic hydroxyl group were added. The non-volatile content of the target resin (A) having an epoxy equivalent of 280 is 70 in the same manner as in Reference Example 6 except that the content is changed to 18.
% Solution was obtained. Hereinafter, this is abbreviated as resin (A-7).

Reference Example 13 [Preparation Example of Curing Agent (B) for Amine Epoxy Resin Room Temperature Curing] In a four-necked flask equipped with a stirrer, a nitrogen introducing device, a dropping funnel and a thermometer, 100 g of triethylenetetramine was added. Charge, raise the temperature to 80 ° C while purging with nitrogen gas,
When the temperature reached the same, "Epicoat 1001" (epoxy resin manufactured by Ciel Co., Netherlands; epoxy equivalent = 475,
75% of a 75% xylene solution) was added dropwise over 2 hours, the temperature was further raised to 100 ° C. and stirring was continued for 2 hours, and then residual triethylenetetramine was removed by distillation under reduced pressure, followed by 53.8 g. Toluene and n-butanol were added each to give an amine value of 380,
And a solution of the target compound having an active hydrogen equivalent of 125 (B-
1) was obtained.

Reference Example 14 (same as above) 64.4 g of diethylenetriamine, 216.8 g of Versadim 216 (Henkel Shiramizu Co., Ltd.) were placed in a four-necked flask equipped with a stirrer, a nitrogen introducing (blobbling) device, a distillation device and a thermometer. Dimer acid, acid value 194) 36.1
g Hartall FA No. 3 (monomer acid manufactured by Harima Kasei Co., Ltd., acid value 194) was charged, and while bubbling nitrogen gas, the temperature was held at 230 ° C. and held, and the acid value was checked every hour. When the acid value reaches 1 or less, 15
The temperature was lowered to 0 ° C., and 110.9 g of xylene 47.5 g of n-
Butanol was added to obtain a curing agent solution (B-2) having an amine value of 122 and an active hydrogen equivalent of 337.

Examples 1 to 36 and Comparative Examples 1 to 13 Polyfunctional epoxy resins (A) obtained in Reference Examples 5 to 11
And the amino group-containing compound obtained in Reference Example 2
˜4. The compounding ratio (solid content weight ratio) shown in Table 4 was used, and the mixture was agitated and mixed by a conventional method to obtain the objective resin composition of the present invention and a control resin composition.

However, in obtaining the control resin composition, instead of the polyfunctional epoxy resin (A), commercially available epoxy resins were used as "Epiclon 860" and "Epiclon 1050" (manufactured by the same company). Epichlorohydrin / bisphenol A type epoxy resin; epoxy equivalent = 475) was used.

Then, for each of the resin compositions thus obtained, a coating film was obtained in the following manner, after which each coating film was evaluated for mechanical properties, corrosion resistance and low temperature curability. Shown together.

1) Coating material: Cold rolled steel plate (0.8 × 70 × 150 m) specified in JIS G-3141
m) according to JIS K-5400-1970, 3.3;
Use the one that has been cleaned by the method specified in (3).

2) Coating method: JI is applied to the above materials.
SK-5400-1970, 3.5; (1) the thickness of the coating film after drying is 100 ± in the clear test.
3 μm, 300 ± in pure test and tar test
Apply to 3 μm.

3) Coating film drying method: Drying in a thermostatic chamber at 25 ° C. for 7 days. 4) Test method and evaluation [Humidity resistance test and salt water spray resistance test] The humidity resistance tester and the salt water spray resistance tester were used in a conventional manner, and the degree of change of the coated surface before and after the test was evaluated visually. . [Goggles adhesion test] (Cross cut test) Make 11 scratches on the coated surface with a razor blade at 1 mm intervals to form 11 square grids measuring 1 mm x 1 mm, and attach cellophane tape to this area. After that, peel it off powerfully. [Pencil Hardness] Drying at 25 ° C. according to JIS K-5401 (1969), evaluated for 24 hours by evaluation.

[0049]

[Table 2]

[0050]

[Table 3]

[0051]

[Table 4]

[0052]

[Table 5]

[0053]

[Table 6]

[0054]

[Table 7]

Reference Example 15 [Preparation Example of Polyphenols as Novolac Resin (B)] 228 g of bisphenol-A was dissolved in 70 g of hot water, and 12 g of 20% oxalic acid aqueous solution was added to the solution.
After the temperature was raised to 0 ° C, 41.5% of formalin was added dropwise and kept at the same temperature for 6 hours.
Dehydration was carried out for 3 hours at a temperature of ℃ to obtain a novolak resin derived from bisphenol-A having a melting point of 110 ° C., a phenolic hydroxyl group equivalent of 120, and an average number of functional groups of 60. Hereinafter, this is abbreviated as polyhydric phenol (a-2-5).

Reference Example 16 [Preparation example of polyfunctional epoxy resin (A)] 16.3 g instead of polyhydric phenol (a-2-2)
Polyhydric phenol (a-2-5), that is, at a ratio of 0.14 phenolic hydroxyl groups to 1 epoxy group, and 92.1 g each of methyl isobutyl ketone and xylene. A solution having a nonvolatile content of 60.2% of the target resin (A) having an epoxy equivalent of 320 was obtained in the same manner as in Reference Example 10 except that the solution was changed to. Hereinafter, this is abbreviated as resin (A-7).

Reference Example 17 (same as above) Instead of the polyhydric phenol (a-2-5), 15.7 g
"Nicanol P-100" [phenol-modified xylene resin manufactured by Mitsubishi Gas Chemical Co., Inc .; phenolic hydroxyl group equivalent = 194, molecular weight = 800, average number of functional groups = 4.
1], that is, the epoxy equivalent was 300 in the same manner as in Reference Example 14 except that the ratio of the amount of the phenolic hydroxyl group to 0.08 per 1 epoxy group was used.
A non-volatile content of the target resin (A) was 59.8%. Hereinafter, this is abbreviated as resin (A-8).

Reference Example 18 (Same as above) In the same manner as in Reference Example 5, 190 g of "Epiclone 85
0 ", and 65.5 g of bisphenol-A and 0.5 g of a 1% sodium hydroxide aqueous solution are reacted at 140 ° C for 4 hours to obtain an intermediate diglycidyl ether having an epoxy equivalent of 600, and then 15.7 g. Polymerization agent polyhydric phenol (a-2-1), that is, at a ratio of 0.13 phenolic hydroxyl groups to 0.43 epoxy groups is added and reacted at 160 ° C. for 7 hours, The non-volatile content of the resin (A) having an epoxy equivalent of 980 is 59.6 by adding 90.4 g of methyl isobutyl ketone and xylene.
% Solution was obtained. Hereinafter, this is abbreviated as resin (A-9).

Examples 37 to 45 In the same manner as in the above Examples and Comparative Examples, the objective composition of the present invention was obtained, and then a coating film was obtained. Then, the same evaluation was made for each coating film. The results are summarized in Table 6.

However, Examples 37 to 39 are cases of clear paints, Examples 40 to 42 are cases of enamel paints, and Examples 43 to 45 are cases of tar / epoxy resin paints.

[0061]

[Table 8]

[0062]

According to the present invention, a coating film having an extremely high hardness can be obtained under a natural drying effect condition at a temperature higher than 10 ° C. for an epoxy-amine type resin composition.

Claims (1)

[Claims] 1. (A) It has two glycidyl ether groups derived from a diphenol compound having a bifunctional phenolic hydroxyl group in the same molecule and has an epoxy equivalent of 1.
It is a novolac resin obtained from an epoxy resin (a-1) of 00 to 800, a monophenol compound and / or a diphenol compound, and formaldehyde, and the average number of functional groups in one molecule is 2.3 to 6. The polymerizing agent (a-2) made of a novolak resin was used in such a manner that one epoxy group in the epoxy resin (a-1) had a phenolic hydroxyl group of 0. Epoxy resin composition comprising a polyfunctional epoxy resin having an epoxy equivalent of 200 to 2000 obtained by reacting at a use ratio of 5 or less and (B) a curing agent for room temperature curing of an amine-based epoxy resin as essential components Apply to the material 1
A method for forming a cured coating film which is naturally dried and cured at room temperature higher than 0 ° C.