JPH11116889A - Composition for coating material for inner surface of pipe - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a composition for a coating material for inner surfaces of pipes, usable even for the pipes in which the pipe joints are corroded or already laid pipes and excellent in surface curability, corrosion resistance and adhesion to substrates. SOLUTION: This composition contains (A) a modified unsaturated epoxy ester resin prepared by reacting an epoxy resin with an unsaturated monobasic acid and further reacting the resultant unsaturated epoxy ester resin with an unsaturated acid anhydride in an amount coresponding to 1-20 mol.% based on hydroxyl groups of the unsaturated epoxy ester resin, (B) an unsaturated monomer, (C) glass flakes, (D) a thixotropy imparting agent and (E) zinc methacrylate.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a composition for a pipe inner coating, and more particularly to a pipe inner coating composition using a modified unsaturated epoxy ester resin and having excellent surface curability, corrosion resistance and adhesion to a substrate. It is about.

[0002]

2. Description of the Related Art Flake lining using an unsaturated epoxy ester resin and glass flakes has often been employed for preventing corrosion of an inner surface of an oil tank or the like. Also, pipes in a similar corrosive environment are provided with polyethylene lining at the time of piping work at the factory, but polyethylene lining is not useful for pipes that have corroded pipe joints or that have already been laid. In such a case, if a conventional method of applying a tar epoxy resin is employed, problems such as slow curing and inability to discharge the solvent out of the pipe arise. In addition, it is conceivable to adopt a flare lining using unsaturated epoxy ester resin and glass flake, which has a proven track record in anticorrosion of oil tanks etc. in a similar corrosive environment, but paraffin wax added for imparting surface hardening is considered. The pipes are filled with styrene and do not cure, and the allyl modification of the unsaturated epoxy ester resin to impart surface curability reduces the corrosion resistance.In addition, if the viscosity is increased to prevent paint dripping, the base material will increase There was a problem that the wettability with the adhesive decreased and the adhesive strength decreased.

[0003]

SUMMARY OF THE INVENTION The present invention solves the above-mentioned problems of the prior art and provides a surface hardening, corrosion resistance and base material which can be used for pipes that have corroded or are already laid. An object of the present invention is to provide a pipe inner coating composition having excellent adhesion to materials.

[0004]

Means for Solving the Problems As a result of intensive studies on the above-mentioned problems, the present inventors have found that a modified anticorrosion paint using glass flakes applied for the purpose of preventing corrosion of the inner surface of a pipe is modified with an unsaturated acid anhydride. The inventors have found that the above-mentioned problems can be achieved by blending a saturated epoxy ester resin, a thixotropic agent and the like, and have reached the present invention.

That is, the present invention relates to (A) an unsaturated epoxy ester resin obtained by reacting an epoxy resin with an unsaturated monobasic acid in an amount of 1 to 20 moles relative to the hydroxyl group of the unsaturated epoxy ester resin. % Modified unsaturated epoxy ester resin, (B) unsaturated monomer, (C) glass flake, (D) thixotropic agent and (E) zinc The present invention relates to a composition for coating the inside of a pipe, which contains turf methacrylate.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION The unsaturated epoxy ester resin is obtained by reacting an epoxy resin with an unsaturated monobasic acid. The epoxy resin is not particularly limited as long as it is a compound having two or more epoxy groups in one molecule. For example, the following general formula (1)

Embedded image (Where x is an integer in the range of 0 to 15) is used.

[0007] Commercially available products include Epicoat 828, Epicoat 1001, Epicoat 1004 manufactured by Shell Chemical Co., Ltd., AER-664H and AER-664H manufactured by Asahi Kasei Corporation.
331, AER-337, D.C. E. FIG.
R. 330, D.I. E. FIG. R. 660, D.E. E. FIG. R. 664
And the like. Further, a type in which a part of hydrogen atoms of the above epoxy resin is substituted with halogen (for example, bromine) can also be used. Examples of this type of commercially available products include Etototo YDB-400, YDB-340, Sumitomo Chemical's Sumiepoxy ESB-340, ESB-400, ESB
-500, RSB-700, DER- manufactured by Dow Chemical Company
542, DER-511, DER-580, 1045, 1050, 1046, DX-248 manufactured by Yuka Shell.

The following general formula (2)

Embedded image (Wherein, R ¹ , R ² and R ³ each independently represent a hydrogen atom or an alkyl group, and x is an integer in the range of 0 to 15)
Can also be used.

[0009] Commercially available products include D.C. E. FIG. N. 431; E. FIG. N. 438, Epicoat 152 and Epicoat 154 manufactured by Shell Chemical Co., Ltd., EPN1138 manufactured by Ciba, and the like. Also, ERL4211 manufactured by Union Carbide, CY2 manufactured by Ciba Geigy
08, CY221, CY350, XB2615, CY1
92, CY184, etc. are also used. These epoxy resins can be used alone or in combination of two or more.

As unsaturated monobasic acids, methacrylic acid,
Acrylic acid, crotonic acid, cinnamic acid, sorbic acid and the like can be used, and these can also be used in combination. Generally, it is preferable to use methacrylic acid from the viewpoint of corrosion resistance. α, β-unsaturated monobasic acid has an equivalent ratio of epoxy group to carboxyl group (epoxy group / carboxyl group) of 1.
It is preferably used so as to be 6 to 0.6, more preferably 1.3 to 0.8.

As the unsaturated acid anhydride to be reacted with the unsaturated epoxy ester resin, unsaturated dicarboxylic anhydrides such as maleic anhydride, itaconic anhydride and citraconic anhydride can be used. The unsaturated acid anhydride reacts with the hydroxyl group of the unsaturated epoxy ester resin (that is, assuming that one unsaturated acid anhydride reacts with one hydroxyl group, 1 to 20% by mole (based on the maximum number of moles), preferably 2 to 20%
It is used in a proportion corresponding to 20 mol%. If the amount of the unsaturated acid anhydride used is out of the above range, the storage stability of the modified unsaturated epoxy ester resin is poor, and the resin tends to gel.

In the reaction between the epoxy resin and the unsaturated monobasic acid and unsaturated acid anhydride, as addition catalysts, halides such as zinc chloride and lithium chloride, sulfides such as dimethyl sulfide and methylphenyl sulfide, and dimethyl sulfoxide , Sulfoxides such as methyl sulfoxide, methyl ethyl sulfoxide, N-N
Tertiary amines such as dimethylaniline, pyridine, triethylamine and hexamethylenediamine and their hydrochlorides or bromates, quaternary ammonium salts such as tetramethylammonium chloride and trimethyldodecylbenzylammonium chloride, and sulfones such as paratoluenesulfonic acid Acids, mercaptans such as ethyl mercaptan and propyl mercaptan, and the like are used. The addition amount of the addition catalyst is 0.05% with respect to 100 parts by weight of the total amount of the epoxy resin, the unsaturated monobasic acid and the unsaturated acid anhydride.
The amount is preferably from 2 to 2 parts by weight, more preferably from 0.1 to 1.0 part by weight.

In order to prevent gelation during the reaction or storage, hydroquinone, tertiary butyl catechol,
Quinones such as p-benzoquinone and 2,5-ditert-butylhydroquinone, and polyhydric phenols, and if necessary, polymerization inhibitors such as amines, nitro compounds, nitroso compounds, and sulfur compounds are used. The compounding amount is preferably used so as to be 0.001 to 5.0 parts by weight based on 100 parts by weight of the total amount of the unsaturated epoxy ester resin (A) and the unsaturated monomer (B). More preferably, it is used in an amount of from 0.01 to 1.0 part by weight.

The unsaturated monomers incorporated in the modified unsaturated epoxy ester resin include styrene, vinyl toluene, ethyl vinyl benzene, isopropyl styrene, tertiary butyl styrene, α-methyl styrene, sec.
-Butylstyrene, divinylbenzene, halogenated styrene, diallyl phthalate, triallyl cyanurate,
Acrylic acid, methacrylic acid, vinyl acetate, acrylates such as methyl acrylate and ethyl acrylate, and methacrylates such as methyl methacrylate and ethyl methacrylate are used. The unsaturated monomer is preferably used in a range of 70 to 10% by weight, and more preferably in a range of 50 to 20% by weight, based on the total amount of the unsaturated epoxy ester resin and the unsaturated monomer. Is more preferred. If the amount of the unsaturated monomer exceeds 70% by weight, the strength and the corrosion resistance tend to decrease, and if it is less than 10% by weight, the viscosity tends to be high and the workability tends to decrease. The unsaturated epoxy ester resin (A) used in the present invention is preferably used as an unsaturated epoxy resin composition obtained by mixing with the unsaturated monomer (B) because of easy handling.

Glass flake (C) used in the present invention
Is a flat glass powder, which is laminated in layers in the coating film in parallel to the coating surface, improving the strength of the coating film and preventing external steam, moisture and other corrosive substances. It has the effect of delaying permeation and suppressing the ingress of water during coating construction. Average thickness of glass flakes is 0.5 to 10 μm
Are preferable, and the size is 50 to 4000 μm on average.
Is preferred. The size of the glass flake refers to the diameter of the largest circumscribed circle in a plan view (actual size projection in the thickness direction) of the glass flake.

If the thickness of the glass flakes is too small, the strength of the glass flakes is low, and the glass flakes are liable to be crushed when mixed with a resin component. If the thickness is too large, the number of parallel-oriented layers in the coating film decreases, The effect of preventing permeation of vapor, moisture and other corrosive substances from the outside is reduced. If the size of the glass flakes is too small, the glass flakes are difficult to be oriented in parallel to the coating surface, and the barrier effect of the glass flakes is reduced, so that the effect of preventing permeation of vapor, moisture and other corrosive substances from the outside is reduced. In addition, the corrosion resistance and the effect of suppressing resin outflow during underwater construction tend to be weak. On the other hand, if the size of the glass flakes is too large, the mixing with the resin component will be poor, and the wettability of the glass flake surface by the resin will tend to be poor. For these reasons, the average thickness of the glass flakes is more preferably 3 to 5 μm, and the average size of the glass flakes is more preferably 100 to 300 μm.

The glass flakes are mixed in an amount of the total amount of the unsaturated epoxy ester resin (A) and the unsaturated monomer (B) of 10%.
It is preferably 10 to 60 parts by weight with respect to 0 parts by weight. If the amount of the glass flakes is too small, the penetration of steam, moisture and other corrosive substances from the outside cannot be prevented, and if the amount is too large, the toughness of the coating film decreases, and the adhesion to the material deteriorates. , Blistering, peeling, easy to cause me. A more preferred amount of the glass flakes is 30 to 50 parts by weight from the viewpoint of the balance between permeation prevention and toughness. Commercially available glass flakes include Nippon Sheet Glass Co., Ltd.
Made glass flakes RCF600, RCF140, RC
F015, REF600, REF140, REF015
Etc. can be used.

Examples of the thixotropic agent (D) used in the present invention include those containing an organic polymer such as fine particle silica, organic bentonite and polyamide as a main component. As the fine particle silica-based thixotropic agent, those commercially available from Nippon Aerosil Co., Ltd., and as the organic bentonite-based thixotropic agent, those commercially available from RHEOX Co., Nissan Gardler Catalysts Co., Ltd. in the United States, and the like,
As the organic polymer-based thixotropic agent such as polyamide, those commercially available from Kusumoto Kasei Co., Ltd., RHEOX Co., USA, Nissan Gardler Catalyst Co., Ltd. and the like can be used.

The amount of the thixotropic agent to be added is preferably adjusted so that the viscosity of the composition for coating the inner surface of the pipe is 20 to 70 Pa · S. From the viewpoint of workability, the viscosity is preferably 30 to 50 Pa · S. It is more preferable to adjust so that If the viscosity of the coating composition for the inner surface of the pipe is low, sagging such as a vertical surface is likely to occur,
In addition, styrene vapor easily swells in the pipe, and if the viscosity is too high, application tends to be difficult. It is preferable that the amount of the thixotropic agent added is adjusted so that the thixotropic degree of the composition for coating the inner surface of a pipe is 3 or more. By setting the degree of rocking to 3 or more, it is possible to further improve sagging resistance on a vertical surface or the like. If the thixotropic degree exceeds 10, stirring at the time of adding the curing agent may be difficult,
A more preferable degree of thixotropicity is 4 to 7.

The viscosity was measured at 25 ° C. according to JIS K 6901 at 25 ° C. using a BL viscometer (rotor # 4, 60 rp).
m). However, the viscosity exceeding the measurement limit (10 Pa · S) of the BL viscometer was measured by a BH viscometer (rotor # 7, 20 rpm). The degree of thixotropicity was determined by measuring the viscosity at 25 ° C. using a BH type viscometer (rotor #).
7) Or a BL-type viscometer (rotor # 4) was used to change the number of rotations of the rotor, and when measured with a BH-type viscometer, the value was calculated by the following formula (a), and was also measured with a BL-type viscometer. At times, it refers to a value calculated by the following equation (b).

(Equation 1)

The zinc dimethacrylate (E) used in the present invention has a structure represented by the following formula (3). The amount used is 1 to 20 parts by weight based on 100 parts by weight of the total amount of the unsaturated epoxy ester resin (A) and the unsaturated monomer (B) from the viewpoint that the viscosity does not become too high and the workability is good. It is preferable to mix by weight, more preferably 2 to 10 weight parts.

Embedded image

[0022] In addition to the above-mentioned components, the composition for coating a pipe inner surface of the present invention comprises a curing accelerator, a curing agent, a polymerization inhibitor, a pigment,
Fillers and the like can be added as necessary. Examples of the curing accelerator include metal salts of fatty acids such as cobalt octenoate, cobalt naphthenate, and manganese naphthenate; and tertiary amines such as dimethylaniline, diethylaniline, dimethylparatoluidine, and diethylmetaluidine. The amount is preferably 0.05 to 5 parts by weight, preferably 0.1 to 1 part by weight, per 100 parts by weight of the total of the unsaturated epoxy ester resin (A) and the unsaturated monomer (B).
Part by weight is more preferred.

As the curing agent, a room temperature curing type is mainly used.
Methyl ethyl ketone peroxide, acetylacetone peroxide, isobutyl ketone peroxide, benzoyl peroxide, cumene hydroperoxide, t-butylperoxybenzoate and the like can be used, and these are used alone or in combination. The compounding amount is 0.5 parts with respect to 100 parts by weight of the total amount of the unsaturated epoxy ester resin (A) and the unsaturated monomer (B).
The amount is preferably from 4 to 4 parts by weight, more preferably from 0.6 to 2.0 parts by weight. In addition, a curing method using thermal polymerization, ultraviolet polymerization, or electron beam polymerization can be employed as necessary.

Examples of pigments and fillers include iron oxide, titanium oxide, aluminum oxide, barium sulfate, calcium carbonate, magnesium carbonate, talc, clay, kaolin, cement, silica, graphite, mica, and asbestos. Pigments and fillers are used not only for coloring the coating composition for the inner surface of pipes and for preventing rust on the object to be coated, but also for adjusting the specific gravity of preventing floating during application in water. The compounding amount is preferably 0.5 to 30 parts by weight, preferably 1.0 to 20 parts by weight based on 100 parts by weight of the total amount of the unsaturated epoxy ester resin (A) and the unsaturated monomer (B). More preferably, Further, if necessary, a silane coupling agent,
A titanium coupling agent, an antifoaming agent, a defoaming agent, a reinforcing material such as glass fiber, a rust preventive, and the like can be added.

[0025]

The present invention will be described below with reference to examples. In the examples, parts and% mean parts by weight and% by weight, respectively, unless otherwise specified. The modified or unmodified unsaturated epoxy ester resin composition in the examples was produced by the following method.

1) Production of Modified Unsaturated Epoxy Ester Resin Composition (I) 450 g of Epikote 828 (Epi-bis type epoxy resin, manufactured by Yuka Shell Co., Ltd., epoxy equivalent: about 186), Epicoat 1001 (Epi-Coat 1001) 920 g of a bis-type epoxy resin, manufactured by Yuka Shell Co., Ltd., having an epoxy equivalent of about 470), 320 g of methacrylic acid, 0.4 g of hydroquinone, and 2.2 g of trimethylbenzylammonium chloride were charged into a flask, and heated at 115 ° C. under an air stream. And stirred vigorously. When the acid value becomes 7, 46 g of maleic anhydride is added, and when the acid value becomes 6, it is rapidly cooled to 910 g.
Was dissolved in styrene and 0.5 g of hydroquinone to obtain a modified unsaturated epoxy ester resin composition (I) modified with an unsaturated acid anhydride.

2) Production of Unsaturated Epoxy Ester Resin Composition (II) 450 g of Epikote 828 (Epi-bis type epoxy resin, manufactured by Yuka Shell Co., Ltd., epoxy equivalent: about 186), Epikote 1001 (Epi-bis In a flask, 920 g of an epoxy resin of the type, manufactured by Yuka Shell Co., Ltd., having an epoxy equivalent of about 470), 320 g of methacrylic acid, 0.4 g of hydroquinone and 2.2 g of trimethylbenzylammonium chloride were charged into a flask, and vigorously stirred at 115 ° C. under an air stream. Stirred.
When the acid value reached 10, the mixture was rapidly cooled and dissolved in 910 g of styrene and 0.5 g of hydroquinone to obtain an unsaturated epoxy ester resin composition (II).

3) Preparation of Allyl-Modified Unsaturated Epoxy Ester Resin Composition (III) 450 g of Epicoat 828 (Epi-bis type epoxy resin, manufactured by Yuka Shell Co., Ltd., epoxy equivalent: about 186), Epicoat 1001 (Epicoat 1001) 920 g of bis-type epoxy resin, manufactured by Yuka Shell Co., Ltd., epoxy equivalent: about 470), 320 g of methacrylic acid, 0.55 g of hydroquinone, and 2.2 g of trimethylbenzylammonium chloride are charged into a flask, and heated at 115 ° C. under an air stream. And stirred vigorously. When the acid value becomes 10, 75 g of phthalic anhydride is added, and when the acid value becomes 11, allyl glycidyl ether is added.
Dissolved in 10 g of styrene and 0.5 g of hydroquinone, an allyl-modified unsaturated epoxy ester resin composition (II
I got.

Example 1 100 parts of a modified unsaturated epoxy ester resin composition (I) modified with an unsaturated acid anhydride was added to Bentonbena.
6 parts of THIX1-4-1 (thixotropic agent, organic bentonite, manufactured by RHEOX Inc., USA), RCF-14
0 (glass flake, trade name of Nippon Glass Fiber Co., Ltd.) 40
Parts, zinc dimethacrylate 6 parts, KBM503 (γ-
1.4 parts of methacryloxypropyltrimethoxysilane (trade name of Shin-Etsu Chemical Co., Ltd.), 0.6 part of a 6% naphthenesancobalt solution and 0.1 part of dimethylaniline were added, and the mixture was stirred and dispersed to obtain a paint. .

Example 2 100 parts of a modified unsaturated epoxy ester resin composition (I) modified with an unsaturated acid anhydride was added to Bentonbenna.
THIX1-4-1 (thixotropic agent, organic bentonite, manufactured by RHEOX Inc., USA) 3 parts, RCF-14
0 (glass flake, trade name of Nippon Glass Fiber Co., Ltd.) 40
Parts, zinc dimethacrylate 6 parts, KBM503 (γ-
1.4 parts of methacryloxypropyltrimethoxysilane (trade name of Shin-Etsu Chemical Co., Ltd.), 0.6 part of a 6% naphthenesancobalt solution and 0.1 part of dimethylaniline were added, and the mixture was stirred and dispersed to obtain a paint. .

Comparative Example 1 100 parts of the unsaturated epoxy ester resin composition (II)
6 parts of BENATHIX 1-4-1 (thixotropic agent, organic bentonite, manufactured by RHEOX Inc., USA), RCF
-140 (Glass flake, trade name of Nippon Glass Fiber Co., Ltd.)
40 parts, KBM503 (γ-methacryloxypropyltrimethoxysilane, trade name of Shin-Etsu Chemical Co., Ltd.) 1.4
, 6 parts of a 6% naphthene cobalt solution and 0.1 part of dimethylaniline were added, stirred and dispersed to obtain a coating.

COMPARATIVE EXAMPLE 2 100 parts of the unsaturated epoxy ester resin composition (II)
BENATHIX 1-4-1 (thixotropic agent, organic bentonite, manufactured by RHEOX Inc., USA) 6.9 parts, R
40 parts of CF-140 (glass flake, trade name of Nippon Glass Fiber Co., Ltd.), KBM503 (γ-methacryloxypropyltrimethoxysilane, trade name of Shin-Etsu Chemical Co., Ltd.)
4 parts, 6 parts of a 6% naphthensan cobalt solution, 0.6 parts of dimethylaniline, and polyset W20T (surface hardening agent, paraffin wax solution, Hitachi Chemical Co., Ltd.)
2.0) was added, and the mixture was stirred and dispersed to obtain a paint.

Comparative Example 3 Allyl-modified unsaturated epoxy ester resin composition (III)
In 100 parts, BENATHIX 1-4-1 (thixotropic agent, organic bentonite, manufactured by RHEOX Inc., USA)
6 parts, RCF-140 (glass flake, Nippon Glass Fiber
(Trade name) 40 parts, KBM503 (γ-methacryloxypropyltrimethoxysilane, Shin-Etsu Chemical Co., Ltd. trade name) 1.4 parts, 6 parts of 6% naphthenesan cobalt solution and dimethylaniline 0.1 Was added and stirred and dispersed to obtain a paint.

COMPARATIVE EXAMPLE 4 100 parts of a modified unsaturated epoxy ester resin composition (I) modified with an unsaturated acid anhydride were added to Bentonbenna.
10 parts of THIX1-4-1 (thixotropic agent, organic bentonite, manufactured by RHEOX Inc., USA), 0.6 parts of a 6% naphthenesancobalt solution and 0.1 parts of dimethylaniline are added, and the mixture is stirred and dispersed to form a coating. And

COMPARATIVE EXAMPLE 5 100 parts of the modified unsaturated epoxy ester resin composition (I) modified with an unsaturated acid anhydride was added to Bentonbena.
6 parts of THIX1-4-1 (thixotropic agent, organic bentonite, manufactured by RHEOX Inc., USA), RCF-14
0 (glass flake, trade name of Nippon Glass Fiber Co., Ltd.) 40
Parts, magnesium dimethacrylate 6 parts, KBM503
(Γ-methacryloxypropyltrimethoxysilane, trade name of Shin-Etsu Chemical Co., Ltd.) 1.4 parts, 0.6 part of a 6% naphthenic acid cobalt solution and 0.1 part of dimethylaniline were added, stirred and dispersed. Paint.

Comparative Example 6 100 parts of the modified unsaturated epoxy ester resin composition (I) modified with an unsaturated acid anhydride were added to Bentonbenna.
6 parts of THIX1-4-1 (thixotropic agent, organic bentonite, manufactured by RHEOX Inc., USA), RCF-14
0 (glass flake, trade name of Nippon Glass Fiber Co., Ltd.) 40
Part, KBM503 (γ-methacryloxypropyltrimethoxysilane, trade name of Shin-Etsu Chemical Co., Ltd.) 1.4 parts, 6
% Naphthene Cobalt solution (0.6 part) and dimethylaniline (0.1 part) were added, stirred and dispersed to obtain a paint.

[Evaluation Method] Each coating material obtained in the above Examples and Comparative Examples was evaluated by the following methods, and the results are shown in Table 1. (A) Surface hardening evaluation method 1) Surface hardening in pipes 1.0 part of 55% methyl ethyl ketone peroxide was added to each paint, and a 1-mm thick guide was applied to both ends of a 10-inch diameter, 30-cm long steel pipe with gum tape. Was prepared, a coating of about 1 mm was applied to the inner surface of the pipe through a 50 cm long glass rod, and both ends were sealed with rubber O-rings and steel plates at room temperature (about 23 ° C).
After leaving for 10 hours, the steel sheet was opened, and the surface curability was evaluated by finger touch as follows. ：: Almost no stickiness. ×: Sticky.

2) Normal surface curability (when styrene vapor does not stay) 1.0 part of 55% methyl ethyl ketone peroxide was added to each paint, and applied to an iron plate to a thickness of about 1.0 mm. (About 23 ° C.), and the surface curability after 20 hours was evaluated by finger touch as follows. ：: No stickiness. Δ: Slight stickiness. ×: Sticky.

(B) Corrosion resistance evaluation method 1) Preparation of samples To each coating material, 0.5 parts of a 6% solution of cobalt octenoate and 1.0 part of 55% methyl ethyl ketone peroxide were added, and a film was formed on both surfaces of a sandblasted steel sheet. About 1 thick
(Mm) It was applied and used as a sample. 2) Corrosion resistance evaluation method Each sample was immersed in a solvent under the following conditions, and the number of days until cracks occurred in the coating film was examined. Immersion liquid: benzene / acetic acid 10 (wt%) aqueous solution = 90 /
10 (% by weight) Immersion temperature: room temperature (20-30 ° C)

(C) Evaluation Method of Adhesive Strength 1) Preparation of Sample To each coating material, 0.5 parts of a 6% solution of cobalt octenoate and 1.0 part of 55% methyl ethyl ketone peroxide were added, and a steel sheet surface-treated with a sander was added. About 1 film thickness on both sides
(Mm) It was applied and used as a sample. 2) Adhesion evaluation method After leaving each sample at room temperature for 20 days, an elcometer (Elcome, UK) was used.
ter Instruments Ltd.) (5)
Average).

[0041]

[Table 1]

Table 1 shows that the coating film using the composition for coating the inner surface of a pipe of the present invention (Examples 1 and 2) is excellent in surface curability, corrosion resistance and adhesive strength. On the other hand, Comparative Example 1 using an unmodified unsaturated epoxy ester resin composition and Comparative Example 2 using a conventional surface-curing agent (paraffin wax) were inferior in surface-curing property and adhesive strength in piping, and were allyl. Comparative Example 3 using the modified unsaturated epoxy ester resin composition shows inferior corrosion resistance and adhesive strength. Further, even when a modified unsaturated epoxy ester resin composition modified with an unsaturated acid anhydride was used, Comparative Example 4 in which glass flakes and zinc dimethacrylate were not used was inferior in corrosion resistance and adhesive strength, and was substituted for zinc dimethacrylate. Comparative Example 5 using magnesium dimethacrylate and Comparative Example 6 not using zinc dimethacrylate show poor adhesion.

[0043]

According to the composition for a pipe inner surface coating of the present invention, a modified epoxy ester resin modified with an unsaturated acid anhydride is used for an anticorrosion coating using glass flakes, and a thixotropic agent and a zinc-free agent are used. Because methacrylate is blended, it is possible to apply a coating with excellent surface hardening properties, corrosion resistance and adhesion to the base material for corrosion prevention on pipes already laid and pipes with pipe seams corroded. .

Claims (1)

[Claims] 1. An unsaturated epoxy ester resin obtained by reacting (A) an epoxy resin with an unsaturated monobasic acid,
A modified unsaturated epoxy ester resin obtained by reacting an unsaturated acid anhydride corresponding to 1 to 20 mol% with respect to the hydroxyl groups of the unsaturated epoxy ester resin, (B) an unsaturated monomer, (C) ) A composition for coating the inner surface of a pipe, comprising glass flakes, (D) a thixotropic agent, and (E) zinc dimethacrylate.