JPH11349861A - Thick-film-type glossy dip coating composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a coating compsn. for dip coating which can be applied thick, is excellent in dryability, and form a glossy coating film. SOLUTION: This compsn. contains an epoxy ester resin and an acrylic resin, the former resin being prepd. by reacting an epoxy resin with an unsatd. fatty acid and grafting, onto the resultant epoxy ester resin, a vinyl monomer.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thick-film glossy dipping paint composition mainly used for anticorrosion coating of inner and outer surfaces of cast iron deformed pipes for water supply and parts attached thereto.

[0002]

2. Description of the Related Art Due to the complicated shape of cast iron deformed pipes for water supply and the parts attached thereto, spray coating or brushing is difficult, and the object to be coated is immersed in the coating to be applied. Dipping painting is widely used.

[0003]

However, in the past, in order to ensure good coating workability such as good wettability and dryness, it was necessary to dilute the paint and apply it to a thin film. Also, in order to paint a thick film at one time, the viscosity of the paint increases and the coating workability including dryness decreases, or if the pigment content in the paint formulation is increased to increase the apparent dryness, the coating will increase. There was a problem that the gloss of the film was reduced. In order to lower the commercial value of the object to be coated with a low-gloss coating film, a glossy top coating material is also subjected to another dipping coating.

[0004]

Means for Solving the Problems The inventors of the present invention have studied to satisfy the contradictory performance requirements of drying property, thick film property, and glossiness of coating film, and as a result, a specific epoxy ester resin and an acrylic resin have been used together. By blending a pigment in a specific ratio therein, a dipping paint having good drying properties and gloss of the coating film was found while securing the required coating film thickness, and the present invention was completed.

That is, the present invention is a thick film type glossy dipping coating composition containing an epoxy ester resin (a) and an acrylic resin (b), wherein the epoxy ester resin (a) is unsaturated with the epoxy resin. A thick film glossy dipping coating composition obtained by graft-polymerizing a vinyl monomer onto an epoxy ester resin obtained by reacting a fatty acid having a group with an epoxy ester resin.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The thick film glossy dipping coating composition of the present invention contains an epoxy ester resin (a) and an acrylic resin (b) as essential components. , Additives,
It is prepared as a mixed one-part paint. In the coating, the coating material and a thinner for dilution are put into a dipping tank, the viscosity of the coating material is adjusted to an appropriate value, and the object to be coated is dipped.

As the epoxy ester resin (a) used in the present invention, a liquid or solid epoxy resin having two or more epoxy groups in one molecule is reacted with a fatty acid having an unsaturated group to esterify it, It is obtained by graft polymerization of an unsaturated group and a vinyl monomer therein, and has a weight average molecular weight of about 10,000 to 20,000,
Those having an acid value of 3 or less can be used.

[0008] When the weight average molecular weight is less than 10,000, the viscosity of the paint can be reduced, which is advantageous for thick film properties. However, there are problems in drying property and corrosion prevention of the coating film. On the other hand, when the weight average molecular weight exceeds 20,000,
Since the viscosity of the paint becomes too high, a large amount of thinner for dilution is required to adjust the viscosity to a suitable viscosity for dipping, which makes it difficult to paint a thick film, which is not preferable. On the other hand, if the acid value of the epoxy ester resin exceeds 3, it is not preferable because it becomes one of the causes of early rust when painted on an iron member.

As the epoxy resin used in the esterification reaction, bisphenol A type, bisphenol F type, bisphenol AD type, or a modified version thereof can be used. The size of the epoxy equivalent of the epoxy resin is not particularly limited. However, in order to obtain an epoxy ester resin having a desired molecular weight, the epoxy equivalent is preferably 450 equivalents.
Those having a size of about 1000 are preferable.

The fatty acid having an unsaturated group used for the esterification includes, but is not limited to, oleic acid, linoleic acid, linoleic acid and the like.
Usually, fatty acids of various oils and fats which are a mixture of these are used.
Examples include safflower oil fatty acids, soybean oil fatty acids, and dehydrated castor oil fatty acids, but the present invention is not limited thereto.

As the conditions for the esterification reaction, known methods can be applied as they are.

As the vinyl monomer used for the graft polymerization, various acrylic acids and their esters, methacrylic acid and their esters, and styrene and acrylonitrile, which are used in the synthesis of ordinary acrylic resins, can be used.

The general radical polymerization conditions can be directly applied to the graft polymerization reaction.

As the acrylic resin (b) of the present invention, various acrylic acids and their esters, methacrylic acid and their esters used in the synthesis of ordinary acrylic resins,
The weight average molecular weight which can be obtained by radical polymerization of vinyl monomers such as styrene and acrylonitrile is 3
Those having a glass transition point of 30 to 70 ° C can be used.

When the weight-average molecular weight is less than 30,000, the viscosity of the coating composition can be lowered, which is advantageous for thick film properties, but may have problems in drying properties and anticorrosion properties of coating films. On the other hand, when the weight average molecular weight exceeds 50,000,
Since the viscosity of the paint becomes too high, a large amount of thinner for dilution is required to adjust the viscosity to a suitable viscosity for the dipping coating, so that it is difficult to paint a thick film. If the glass transition point of the resin is lower than 30 ° C., the drying properties of the dipped coating film tend to be slow, which is not preferable. When the glass transition point exceeds 70 ° C., physical properties such as impact resistance and bending resistance of the coating film tend to decrease.

The (a) epoxy ester resin and (b) acrylic resin of the present invention are used in a mixture at a specific ratio. (A) the mixing ratio of the epoxy ester resin and (b) the acrylic resin is greater than 4: 1 in terms of solid content ratio,
(A) When the proportion of the epoxy ester resin is large, the drying property of the coating film is deteriorated, which is not preferable. On the other hand, when the mixing proportion is smaller than 1: 1, However, it is not preferable because the anticorrosion property is lowered.

The pigments used in the present invention include coloring pigments, extender pigments and rust-preventive pigments. However, when the proportions of these pigments are less than 30% by weight of the solid content of the mixed resin, the coating is carried out. It is not preferable because the film thickness and drying property of the film decrease. On the other hand, if it is more than 80%, the gloss of the dried coating film is undesirably reduced.

The thick film glossy dipping paint of the present invention may further contain additives such as a dispersing agent, a wetting agent, an antifoaming agent, an anti-dripping agent, a thickening agent, a leveling agent and an anti-skinning agent. May be used in combination. Further, various organic solvents that are usually used for adjusting the coating workability and the drying property may be used in combination.

[0019]

EXAMPLES Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples.
“Parts” and “%” are “parts by weight” and “% by weight”
Is shown.

(1) Production of Epoxy Ester Resin (a) (1-1) Esterification Reaction In a reactor equipped with a stirrer, a thermometer, a reflux condenser and a nitrogen condenser, 8 parts of oil fatty acid, Castor oil fatty acid 2
Parts, 5 parts of soybean oil fatty acid, 150 under nitrogen atmosphere
After heating to ℃, 22 parts of a bisphenol A type solid epoxy resin (Note 1) having an epoxy equivalent of about 950, 3 parts of p-tert-butylbenzoic acid, and 1 part of xylene were added.
The temperature was raised to 250 ° C. After maintaining at this temperature for 3 hours to complete the esterification reaction, the mixture was cooled to 180 ° C. or lower to obtain an esterified product.

(1-2) Grafting Reaction A reactor equipped with a stirrer, a thermometer, a reflux condenser, and a nitrogen condenser was charged with 40 parts of xylene, and the esterified product was charged therein. The temperature was raised to 140 ° C, and styrene 9
, A mixture of 3 parts of acrylonitrile and 0.2 part of ditertiary butyl peroxide was added dropwise over 4 hours.
After further aging for 2 hours, 7 parts of xylene and 2 parts of an aromatic mixed solvent (Note 2) were charged and cooled to complete the grafting reaction. The resin properties of the obtained epoxy ester resin solution are as follows:
Non-volatile content 47%, viscosity (Gardner method) U, acid value 2.
5, the weight average molecular weight was 14,000.

(2) Production of acrylic resin (b) 50 parts of xylene was charged into a reactor equipped with a stirrer, a thermometer, a reflux condenser and a nitrogen condenser, and 40 parts of methyl methacrylate and acrylic acid were added thereto. A monomer mixture comprising 8 parts of 2-ethylhexyl, 0.01 part of methacrylic acid and 0.02 part of cumene hydroperoxide was added dropwise over 3 hours under total reflux. After completion of the dropwise addition, the temperature was maintained at the same temperature for 2 hours. The characteristics of the obtained resin solution are as follows:
Viscosity (Gardner method) Z3, weight average molecular weight 40000
Met.

(Note 1) Product name: Epicoat 1004, manufactured by Yuka Shell Chemical Co., Ltd. (Note 2) Product name: Ipsol 100, manufactured by Idemitsu Petrochemical Co., Ltd.

(3) Production of dipping paint Example 1 A mixture of 10 parts of toluene and 20 parts of an epoxy ester resin (a) was mixed with 1 part of carbon black, 5 parts of magnesium silicate, 5 parts of barium sulfate, and 5 parts of zinc phosphate. Part, 4 parts of fatty acid amide wax and 2 parts of oxidized polyethylene wax are sequentially added and mixed by a disper, and dispersed by a sand mill, and as a letdown, 18 parts of an epoxy ester resin (a),
25 parts of acrylic resin (b) and 4 parts of methyl ethyl ketone were added and mixed with a disper to obtain a dipping paint.

Examples 2 and 3 and Comparative Examples 1 to 4 Examples 2 and 3 and Comparative Examples 1 to 4 were carried out in the same manner as in Example 1 except that the compositions and the amounts shown in Table 1 were used. Was obtained.

Each of the coating compositions obtained in Examples and Comparative Examples was subjected to the following performance tests and evaluated. Table 2 shows the results.

[0027]

[Table 1]

[0028]

[Table 2]

(* 1) Coating film thickness: Diluted with a special thinner so as to be 30 seconds as measured by an IHS cup, dipped and polished on a mild steel plate, dried, and dried with an electromagnetic film thickness meter. The thickness was measured. (* 2) Drying property: The coating film dipped in (* 1) was measured for the time required for curing and drying specified in JIS K5400.6.5. (* 3) Gloss of coating film: The coating film dipped and coated in (* 1) was dried for 48 hours, and the 60 ° mirror reflectance was measured. (* 4) 10mm bending according to JIS K5400.8.1.

Explanation of the notation of the performance test results ○: In the salt spray test, no abnormality such as rust or blister is observed on the surface of the coating film. In the bending resistance test, no abnormalities such as wrinkles and wrinkles are observed in the bent portion of the coating film. X: In the salt spray test, abnormalities such as rust and blisters are observed on the surface of the coating film. Further, in the bending resistance test, abnormalities such as wrinkles and wrinkles are recognized in the bent portion of the coating film.

(Note 3) Product name: Dispalon 6900-20X manufactured by Kusumoto Kasei Co., Ltd. (Note 4) Product name: Dispalon 42 manufactured by Kusumoto Kasei Co., Ltd.
00-20

[0032]

EFFECT OF THE INVENTION By using the coating composition of the present invention for dipping coating, it is possible to coat a thick film of 80 μm or more with one coating, and it has excellent workability such as quick drying and obtains the obtained coating. Since the film is glossy and has good anticorrosion properties and physical properties, it is suitable for anticorrosion coating of inner and outer surfaces of cast iron deformed pipes for water supply and parts attached thereto.

Claims (3)

[Claims] 1. A thick film glossy dipping coating composition containing an epoxy ester resin (a) and an acrylic resin (b), wherein the epoxy ester resin (a) is an epoxy resin and a fatty acid having an unsaturated group. A thick film glossy dipping coating composition obtained by graft-polymerizing a vinyl monomer onto an epoxy ester resin obtained by reacting 2. The mixing ratio of the epoxy ester resin (a) and the acrylic resin (b) is from 1: 1 to 4: 1 in terms of solid content.
And the proportion of the pigment to be added to them is
30 to 80% by weight based on the solid content of the mixed resin
The thick film type glossy dipping coating composition according to claim 1, wherein: 3. A dry film thickness of 80 μm or more can be obtained by one dipping coating, and a 60 ° specular reflectance of the coating film is 3
The thick film type glossy dipping coating composition according to claim 1, wherein the coating composition is 0% or more.