JPH064821B2 - Aqueous coating composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Field of Industrial Application> The present invention relates to an aqueous coating composition having an excellent anticorrosive property, which comprises a bituminous substance forced emulsion water dispersion and an epoxy resin water dispersion.

<Conventional technology and its problems> Conventionally, paints using bituminous substances such as coal tar epoxy paints have extremely low water permeability, and thus have excellent corrosion resistance and are inexpensive, so steel materials and cast iron materials. It has been widely used as a long-term anticorrosion paint, but because coal tar epoxy paint uses a relatively large amount of organic solvent, it is a water dispersion in which a bituminous substance is forcibly emulsified in water from the viewpoint of pollution control and resource saving. Attention has been focused on a low-pollution type water-based coating material which is composed of a mixture of a liquid and an aqueous dispersion of an epoxy resin and which suppresses the amount of the organic solvent used as much as possible.

However, in order to stably emulsify the aqueous dispersion in which the bituminous substance is forcibly emulsified in water, it is necessary to add a large amount of a surfactant, and therefore, the hydrophilicity of the surfactant in the resulting coating film. Since many groups remain, the water resistance and moisture resistance are poor,
There was a problem that the original characteristics of the anticorrosion paint could not be fully utilized. In addition, a uniform aqueous dispersion cannot be obtained unless the stirring blades and stirring conditions for forcedly emulsifying the bituminous substance into water are obtained, and the obtained aqueous dispersion has poor stability. There was a problem.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and an object thereof is to provide an aqueous coating composition which solves the above-mentioned problems through intensive studies.

<Means for Solving Problems> That is, the present invention is (A) 100 parts by weight of coal tar pitch having a softening point of 50 to 150 ° C., (B) an extremely high temperature oxidation-polymerizable water-soluble compound having an acid value of 40 to 130. 5 to 30 parts by weight of a water-soluble acrylic resin which is an acrylic resin neutralized with 0.5 to 1.5 chemical equivalents to the acid groups of the acrylic resin, (C) 5 to 20 parts by weight of a self-emulsifying polyamide resin, (D ) Nonionic surfactant 5 to 10 parts by weight, and (E) required amount of water, bituminous substance forced emulsified water dispersion liquid 50 to 80% by weight
(In terms of solid content) and (II) aqueous dispersion of epoxy resin 50 to 20 wt% (in terms of solid content).

The aqueous coating composition of the present invention requires a small amount of surfactant, and thus the obtained coating film has excellent water resistance and corrosion resistance. In addition, since the component (I) uses a water-soluble acrylic resin having an acid value of 40 to 130 and a self-emulsifying polyamide resin as a polymer protective colloid component in combination with a surfactant, a coal tar pitch, which is a bituminous substance, is used. An aqueous dispersion that can be easily emulsified in water and has excellent mechanical stability and thermal stability can be obtained. Further, the self-emulsifying polyamide resin is characterized by being capable of forming a coating film excellent in anticorrosion property because it is cross-linked and cured with the epoxy resin of the component (II) at room temperature or by heating.

In the present invention, the coal tar pitch (A), which is a constituent of the component (I), contains a large amount of a polycyclic aromatic polymer substance soluble in an organic solvent in addition to free carbon. Any of α-bitumen, β-bitumen, and γ-bitumen classified according to the difference in solubility of the components in various solvents can be used. However, it is necessary to use a coal tar pitch having a softening point of 50 to 150 ° C. If the softening point is lower than the above range, the resulting coating film becomes tacky and the blocking resistance and the like decrease. If it is higher than the range, it becomes difficult to obtain an emulsion of fine particles,
In addition, the flexibility of the obtained coating film is lowered, and thus both are not preferable. The coal tar pitch can be used by dissolving it in a small amount of an organic solvent, for example, an aromatic solvent such as xylene or toluene, or an ester solvent such as ethyl acetate or butyl acetate. However, it is preferable not to use an organic solvent from the viewpoint of low pollution, and if not used, it is dispersed in water while being heated and melted, if necessary, during the production of a forced emulsified water dispersion described later.

The water-soluble acrylic resin (B) in the present invention is styrene,
Hard monomers such as methyl methacrylate, ethyl methacrylate, butyl methacrylate, and acrylonitrile; soft monomers such as methyl acrylate, ethyl acrylate, butyl acrylate, and 2-ethylhexyl acrylate; carboxyl groups such as acrylic acid and methacrylic acid A mixed monomer obtained by appropriately combining the contained monomers in consideration of the compatibility with the component (A) has a number average molecular weight of about 1,000 to 50,00 by a usual method.
A carboxyl group-containing copolymer obtained by copolymerization so as to be 0 is neutralized with a neutralizing agent. As the neutralizing agent, usual neutralizing agents such as ammonia, diethylamine, triethylamine, monopropylamine, dipropylamine, monoethanolamine, diethanolamine, triethanolamine, dimethylaminoethanol, diethylaminoethanol, etc. can be used. , These neutralizing agents are 0.5 to 1.5 with respect to the acid groups of the copolymer.
Add a chemical equivalent and neutralize.

A water-soluble acrylic resin having an acid value of 40 to 130 is suitable, and in this range, it has good compatibility with the component (A), and when the acid value is less than the above range, the solubility in water becomes insufficient, and (A)
If the component does not function as a polymer protective colloid, on the contrary, if it exceeds the above range, the water resistance, chemical resistance and the like of the resulting coating film tend to be deteriorated, which is not preferable either.

The self-emulsifying polyamide resin (C) in the present invention is a liquid resin having amino groups at both ends obtained by reacting dimer acid and excess ethylenediamine, and polyamines such as diethylenetriamine, and is a commercially available product "Epolsion EB-3". , "Evolution EB-4", "Evolution EB-5" (above, Kanebo NSC product name),
"Epocure 3255" (trade name of Yuka Shell Epoxy Co., Ltd.), "TOMIDE SH-22X" (trade name of Fuji Kasei Kogyo Co., Ltd.) and the like can be mentioned.

The nonionic surfactant (D) in the present invention is an ethylene oxide-based surfactant, a diethanolamine-based surfactant, an anhydrosorbitol-based surfactant, a glycoside, a gluconamide-based surfactant, glycerin, a glycidol-based surfactant. Etc. are mentioned as a typical thing. Especially HLB (Hydrophile-Lipophile Balance) 14
Those having an amount of up to 20 have a remarkable effect on the emulsifying action of coal tar pitch, and are therefore preferred.

The solid content of the component (1) in the present invention includes the above-described components (A), (B), (C) and (D) as essential components, and the mixing ratio thereof is (A) component 100. (B) for parts by weight
5 to 30 parts by weight of component, 5 to 20 parts by weight of component (C), (D)
5-10 parts by weight of the components are suitable. In addition, (B) component, (C)
If the content of any one of the component and the component (D) is less than the above range, a bituminous substance forced emulsified aqueous dispersion is difficult to obtain, and problems in practical use occur in mechanical stability, thermal stability, wire mesh filterability, and the like. On the other hand, if the amount exceeds the above range, the resulting coating film tends to have poor water resistance, chemical resistance and the like, which is not preferable.

(I) component bituminous substance forced emulsified water dispersion is a heated melt of component (A) or a dissolved product of a small amount of an organic solvent.
The components (B), (C) and (D) are stirred and mixed with a closed stirring mixer, a ball mill, a pebble mill, etc., and the mixture is gradually added while stirring with a stirring mixer. An emulsified water dispersion is prepared. The amount of water added is preferably (A) component, (B) in order to obtain a stable emulsion water dispersion.
Ingredient, (C) component and (D) component have a solid content of 37 to 70% by weight
An appropriate amount is

The component (II) in the present invention is an aqueous dispersion of an epoxy resin, and it is also used as a curing agent component for the main component of the component (I), and is mixed with the component (I) immediately before coating to prepare an aqueous solution of the present invention. Form a coating composition. The epoxy resin which is a constituent of the component (II) has a molecular weight of about 350 to 2000 and an epoxy equivalent of about 170 to 10 having one or more epoxy groups in one molecule.
00 in a liquid or solid form. Most commonly, it is a condensate of bisphenol A and epichlorohydrin, but other than this, glycidyl ether of bisphenol F, glycidyl ether of dimer acid, polyalkylene glycol glycidyl ether, urethane-modified bisphenol glycidyl ether, aliphatic aromatic co-condensed glycidyl ether, Hydrogenated bisphenol glycidyl ether and the like can be mentioned.

The aqueous dispersion of epoxy resin is obtained by dispersing the above epoxy resin in water in the presence of an emulsifier, and the epoxy resin solid content is preferably about 40 to 70% by weight.

The aqueous coating composition of the present invention comprises the above-mentioned component (I) and component (II), and the mixing ratio of both is [(50-
80): (50 to 20)] (weight basis) is suitable.
If the amount of component (I) is less than the above range, the resulting coating film will have poor drying properties, and if it is too large, it will have poor corrosion resistance, adhesion, chemical resistance, etc.

Incidentally, the epoxy resin of the component (II) mainly undergoes a cross-linking reaction with the active hydrogen of the self-emulsifying polyamide resin in the component (I). When the amount of the resin is large within the above range, the reaction with a sufficient crosslinking density cannot be performed. In that case, a normal non-self-emulsifying aqueous polyamide resin emulsion can be added to the component (I). The blending amount of the non-self-emulsifying aqueous polyamide resin emulsion may be such that the epoxy equivalent of the epoxy resin and the total active hydrogen equivalent ratio of the self-emulsifying polyamide resin and the non-self-emulsifying polyamide resin are 0.6 to 1.3. .

In the present invention, if necessary, various additives such as a rust preventive pigment, a coloring pigment, an extender pigment, a filler such as an aggregate, an anti-sagging agent, a leveling agent, an anti-settling agent or various modifying resins may be added. It is also preferable that these are mixed in advance with either the component (I) or the component (II).

The aqueous coating composition of the present invention comprises the above components and can be applied by means such as spraying, brushing, rolling, etc., and a cured coating film can be obtained by natural drying or forced drying at about 80 ° C. or lower.

<Effects of the Invention> As described above, the present invention does not contain an organic solvent or uses an extremely small amount, so that low pollution and resource saving are possible. Also, by reducing the amount of surfactant used and using a specific water-soluble acrylic resin and self-emulsifying polyamide resin as a polymeric protective colloid component instead, a stable emulsified water dispersion of coal tar pitch can be obtained. ,
In addition, the resulting coating film has excellent water resistance and the like, and is therefore useful as a long-term anticorrosion coating material.

<Example> Hereinafter, the present invention will be described in more detail with reference to Examples. In addition, "part" and "%" in the examples are shown by weight.

Reference Example 1 <Preparation of pigment base> Water 40 parts Carbon black 3 parts Calcium carbonate 56 parts Hydroxyethyl cellulosic thickener 0.2 parts Pigment dispersant 0.8 parts Kneading dispersion for 16 hours in a ball mill To prepare a pigment base.

Example 1 Coal tar pitch solution prepared by heating and melting 100 parts of coal tar pitch having a softening point of 90 to 100 ° C. and dissolving with 25 parts of xylene; water-soluble acrylic resin solution (“Watersol S798” (Dainippon Ink and Chemicals Incorporated) Product name),
Solid content 40%, acid value 85, number average molecular weight 7,000, ammonia 1.0 chemical equivalent neutralization] 62.5 parts; self-emulsifying polyamide resin [(Tomade SH-22X] (trade name, manufactured by Fuji Kasei Kogyo KK), solid content 100% , Active hydrogen equivalent 115, amine value 345] 10 parts; 6 parts of nonionic surfactant [“Emulgen 985” (trade name of Kao Corporation, HLB19)] are kneaded in a ball mill for 10 hours and then taken out to a disper-type stirrer. While stirring, 78.5 parts of warm water (60 ° C.) was gradually added to obtain a uniform dispersion liquid of a bituminous substance compulsively emulsified, to which 80 parts of the pigment base and a non-self-emulsifying water-based polyamide resin emulsion were added. "Yukaresin H-35"
(Yoshimura Kosan product name), solid content 45%, amine value 12
0] 11.1 parts were added and uniformly mixed with stirring to obtain a main ingredient.

On the other hand, as a curing agent component, an aqueous dispersion of epoxy resin [“Yukaresin 1022” (trade name of Yoshimura Kosan Co., Ltd.), solid content 55
%, Epoxy equivalent of 1100 to 1200], and uniformly mix 27 parts of the curing agent component (epoxy resin solid content 14.9 parts) and 73 parts of the main component (total solid content of components (A) to (D) 27.6 parts). Mix to prepare an aqueous coating composition.

Example 2 100 parts of a heated melt of coal tar pitch having a softening point of 60 to 70 ° C .; a water-soluble acrylic resin solution [“Watersol 744” (trade name, manufactured by Dainippon Ink and Chemicals, Inc.), solid content: 40%, acid value: 85, number average molecular weight 7,000, 1.0 neutral equivalent of ammonia neutralization] 50 parts; self-emulsifying polyamide resin water dispersion [[Epicure 325
5 "(trade name of Yuka Shell Epoxy Co., Ltd.), solid content 50
%, Amine value 170] 40 parts; nonionic surfactant ["Emulgen 911" (trade name, manufactured by Kao Corporation), HLB1
3.7] After thoroughly mixing 8 parts with a homogenizer, 98 parts of warm water (65 ° C.) was gradually added with stirring to obtain a forced emulsified water dispersion of a bituminous substance. To this dispersion, 80 parts of the pigment base was added and uniformly mixed with stirring to obtain a main component.

On the other hand, 20 parts of water was added to 40 parts of an epoxy resin [“Epicoat DX-255” (trade name, manufactured by Yuka Shell Epoxy Co., Ltd., solid content 100%, epoxy equivalent 182 to 212), and an emulsified epoxy resin water dispersion liquid was added. That is, a curing agent component was obtained. Next, 14 parts of curing agent component (epoxy resin solid content 9.
3 parts) and the main ingredient 86 parts (total solids of components (A) to (D) 33.9
Parts) were uniformly mixed to prepare an aqueous coating composition.

Example 3 Coal tar pitch solution prepared by heating and melting 100 parts of coal tar pitch having a softening point of 80 to 90 ° C. and dissolving with 25 parts of xylene; water-soluble acrylic resin solution (solid content 40%, acid value 100, number average molecular weight) 20000, ammonia 1.0 chemical equivalent neutralization) 32.5 parts; self-emulsifying polyamide resin ["Tomide SH-22X"] 8.2 parts; nonionic surfactant ["Emulgen 985"] 7 parts, after uniformly mixing with a homogenizer, While stirring, 83.5 parts of warm water (60 ° C.) was gradually added to obtain a forced emulsified water dispersion of a bituminous substance. To this dispersion was added 15 parts of a non-self-emulsifying type water-based polyamide emulsion [“Epoljon EB-1” (trade name of Kanebo NSC Co., solid content 45%, amine value 117),
The components of the main agent were obtained by uniformly stirring and mixing.

On the other hand, an epoxy resin aqueous dispersion [“Epolsion EA-55” (Kanebo NSC product name) as a curing agent component,
Solid content 55%, epoxy equivalent 850-950], and the curing agent component 37 parts (epoxy resin solid content 20.4 parts)
And 63 parts of the main ingredient (total solid content of components (A) to (D) 29.8 parts) were uniformly mixed to prepare an aqueous coating composition.

Example 4 In Example 1, 20 parts of the water-soluble acrylic resin solution and 18 parts of the self-emulsifying polyamide resin were added, and warm water of 95 parts was used.
And 38 parts (epoxy resin solid content 20.9 parts) and 62 parts (components (A) to (D), respectively)
Was prepared in the same manner as above, except that the total solid content was 23.0 parts).

Example 5 In Example 1, 50 parts of the water-soluble acrylic resin solution, 6 parts of the self-emulsifying polyamide resin, 9 parts of the nonionic surfactant, 80 parts of warm water, and the curing agent component and the main component were used. 28 parts each (epoxy resin solid content 15.4 parts), 72 parts (total solid content of components (A) to (D) 26.9 parts)
An aqueous coating composition was prepared in the same manner except that

Comparative Example 1 The water-soluble acrylic resin solution in Example 1 was 7.5 parts, and the curing agent component and the main component were 29.3 parts (epoxy resin solid content 16.1 parts) and 70.7 parts (total of components (A) to (D), respectively). An aqueous coating composition was prepared in the same manner except that the solid content was 26.4 parts).

Comparative Example 2 In Example 2, the self-emulsifying polyamide resin aqueous dispersion was made into 4 parts, and the curing agent component and the main component were each 1.
7 parts (epoxy resin solid content 1.1 parts), 98.3 parts (component (A) ~
An aqueous coating composition was prepared in the same manner except that the total solid content of (D) was 37.6 parts).

Comparative Example 3 In Example 3, the nonionic surfactant was 1 part, and the curing agent component and the main component were 34 parts (epoxy resin solid content 18.7 parts) and 66 parts (total of components (A) to (D), respectively). Solid content
An aqueous coating composition was prepared in the same manner except that the amount was 30.2 parts).

Comparative Example 4 The water-soluble acrylic resin solution in Example 1 was made 100 parts, and the curing agent component and the main component were respectively 25.2 parts (epoxy resin solid content 13.9 parts) and 74.7 parts (total of components (A) to (D)). An aqueous coating composition was prepared in the same manner except that the solid content was 28.4 parts).

Comparative Example 5 In Example 2, the self-emulsifying polyamide resin aqueous dispersion was made 80 parts, and the curing agent component and the main component were each 2 parts.
2.4 parts (epoxy resin solid content 14.9 parts), 77.6 parts (component (A)
~ (D) 31.3 parts total solids) was prepared in the same manner as above except that the aqueous coating composition was prepared.

Comparative Example 6 In Example 3, 20 parts of nonionic surfactant was used,
In addition, an aqueous coating composition was prepared in the same manner except that the curing agent component and the main component were each 31 parts (epoxy resin solid content 17.1 parts) and 69 parts (total solid content 34.3 parts of components (A) to (D)). Prepared.

Comparative Example 7 In Example 2, instead of the self-emulsifying polyamide resin water dispersion, a non-self-emulsifying polyamide resin water dispersion [Eponyl KP-300 (Nippon Gosei Co., Ltd.), solid content 5
0%] was used to prepare an aqueous coating composition in the same manner as in Example 2.

The aqueous coating compositions obtained in the above Examples 1 to 5 and Comparative Examples 1 to 7 were degreased on a polished mild steel sheet to give a dry film thickness of 90 to 1
Air spray paint to 00μ, 60 ℃ × 15
After drying for 2 minutes and leaving it at room temperature for 2 days, it has moisture resistance, salt water spray resistance,
Various tests of water resistance, flex resistance and impact resistance were conducted, and the results are shown in Table 1. Further, the storage stability of the main ingredient was measured, and the results are shown in Table 1. In addition, a cosmetic test was conducted to investigate the emulsified state of the main ingredient, and the results were
Shown in the table. As is clear from Table 1, the aqueous coating composition of the present invention had excellent coating film performance and good storage stability.

On the other hand, the water-soluble acrylic resin, the self-emulsifying polyamide resin, and Comparative Examples 1 to 3 having a small amount of nonionic surfactant all had poor cosmetic resistance and poor storage stability. On the contrary, in Comparative Examples 4 to 6 in which the water-soluble acrylic resin, the self-emulsifying polyamide resin, and the nonionic surfactant were excessive, the moisture resistance, salt spray resistance, and water resistance were all poor.

In addition, in Comparative Example 7 in which a non-self-emulsifying polyamide resin was used instead of the self-emulsifying polyamide resin, the storage stability and the elasticity were poor.

Note 7) Place a few grams of the main ingredient on a tin plate and use your fingers to do 3
Rub 0 times and wash with water.

◯: The main ingredient is washed away. X: Emulsion particles are attached.

Incidentally, the case where the emulsion particles adhere and remain is caused when the emulsion particles are not sufficiently emulsified.

Claims (2)

[Claims] 1. An extremely high temperature oxidation-polymerizable water-soluble acrylic resin having (A) 100 parts by weight of coal tar pitch having a softening point of 50 to 150 ° C., and (B) having an acid value of 40 to 130. Water-soluble acrylic resin neutralized with 0.5 to 1.5 chemical equivalents to acid groups, 5 to 30 parts by weight, (C) self-emulsifying polyamide resin 5 to 20 parts by weight, (D) nonionic surfactant 5 to 10 50 parts by weight of a bituminous substance forced emulsified water dispersion comprising 50 parts by weight and (E) a required amount of water 2. An aqueous coating composition comprising 50 to 20% by weight (in terms of solid content) of an epoxy resin aqueous dispersion.