JPH04331274A - Quick-drying, corrosion-resistant, aqueous coating composition - Google Patents

Abstract

PURPOSE:To provide the title compsn. which exhibits excellent drying properties whether it is dried at normal temp. or under heating and gives a coating film excellent in corrosion resistance. CONSTITUTION:The title compsn. which contains an alkyd resin or a deriv. thereof typified by an aq. epoxy ester dispersion, a polymer emulsion typified by an acrylic or acrylic styrenic polymer emulsion prepd. by the polymn. of a monomer mixture contg. an unsatd. carboxylic acid as a comonomer using an org. peroxide as a polymn. initiator, and optionally a pigment.

Description

[Detailed description of the invention]

0001

FIELD OF THE INVENTION This invention relates to new and useful aqueous coating compositions. More specifically, it contains an alkyd resin or a derivative thereof and an emulsion polymer as essential film-forming components, and further contains a pigment if necessary, and has quick-drying properties, especially in air-drying and heat-drying. The present invention relates to an aqueous coating composition which also has excellent corrosion resistance.

0002

2. Description of the Related Art Various anti-corrosion paints have been used so far for the purpose of coating metal materials to prevent rust.

Most of them are oil-based paints, and the large amount of organic solvents they contain are not only undesirable from a work and safety standpoint, but can also be a source of environmental pollution, so in recent years, water-based paints have become more popular. Demand for transformation is increasing.

By the way, the water-based paint in question contains a water-soluble or water-dispersible so-called water-based resin as a vehicle, but in order to improve the solubility and dispersibility of the resin in water, It is often obtained by including a large amount of carboxyl groups, hydroxyl groups, or ethylene oxide groups in the resin, or by adding a dispersing component such as an emulsifier.

[0005] Therefore, the water-based resin has a high water-retention property, and combined with the latent heat of vaporization of water, which is the main solvent, the drying properties of water-based paints are lower than those of oil-based paints. This is hindering its spread.

[0006] Therefore, in order to improve the drying properties of such water-based paints, it is possible to solve the problem by using a large amount of SBR latex, acrylic-based or acrylic-styrene-based emulsion polymer as a paint vehicle. However, in such a case, the anticorrosion properties of the resulting coating film tend to deteriorate, and in the end it cannot be said to be preferable.

[0007]

[Problems to be Solved by the Invention] However, the present inventors have attempted to improve the slow drying properties of conventional water-based paints as described above without impairing the anti-corrosion properties of the paint film.
I did a lot of research.

[0008] Therefore, the problem to be solved by the present invention is to provide an aqueous coating composition that has quick-drying properties in air-drying and heat-drying, and has excellent corrosion resistance. be.

[0009]

[Means for solving the problem] Therefore, the present inventors
As a result of intensive studies aimed at the problems to be solved by the invention as described above, we have developed an alkyd resin or its derivative having a specific resin solid content acid value, a specific theoretical glass transition temperature, and a particle size. The present inventors have discovered that a water-based paint containing a specific ratio of an emulsion polymer as a binder exhibits excellent drying properties, and the resulting paint film also has excellent anticorrosion properties, leading to the completion of the present invention. .

That is, the present invention basically contains an alkyd resin or its derivative (A) and an emulsion polymer (B) as essential components, or alternatively, the alkyd resin or its derivative (A) ), an emulsion polymer (B),
The purpose of the present invention is to provide an aqueous coating composition containing a pigment (C), and specifically, an alkyd resin or a derivative thereof (A) having a solid content acid value of 10 to 50, respectively, and a solid content acid value of 10 to 50. 10 to 40% by weight, a theoretical glass transition temperature of 20 to 50°C, and an average particle size of 0.04 to 0.1
Emulsion polymer (B) within a range of 5 microns (μm)
In particular, it relates to an aqueous coating composition having excellent drying properties, comprising 90 to 60% by weight of the solid content of the present invention and, if necessary, an appropriate amount of a pigment.

Here, first, the above-mentioned alkyd resin (A) which is the main component of the aqueous coating composition of the present invention.
Among others, alkyd resins (A
) can be prepared by any known and commonly used method, and is not particularly limited, but if the corrosion resistance of the resulting coating film is also taken into consideration, the use of epoxy ester resin is recommended. If the hardness of the resulting coating film is also considered, it is desirable to use a vinyl-modified epoxy ester resin.

Such an epoxy ester resin, such as a vinyl-modified epoxy ester resin, is made of, for example, 25 to 60 parts by weight of a fatty acid and/or oil, 25 to 60 parts by weight of an epoxy resin, and a resin having 6 to 18 carbon atoms. 0 to 15 parts by weight of a basic acid, 0 to 30 parts by weight of a polyol,
Furthermore, 0 to 20 of the polybasic acid and/or its anhydride
parts by weight to a total of 100 parts by weight, as appropriate, by proceeding with the condensation process until the desired acid value is reached, by a known and commonly used method.

In other words, it is an epoxy ester resin, and the solid content of the epoxy ester resin is 50 to 90.
such as those obtained by polymerizing 50 to 10 parts by weight of an ethylenically unsaturated monomer in the presence of 100 parts by weight in a known and customary manner, i.e. , a vinyl-modified epoxy ester resin.

[0014] Also, in any of these cases,
The solid content acid value of the alkyd resin or its derivative (A) is:
It is necessary that the number is within the range of 10 to 50. If this acid value is less than 10, the dispersibility of the (A) itself in water, the pigment dispersibility, and the adhesion of the film to the substrate will decrease; If it becomes too high, the corrosion resistance and water resistance of the film will inevitably deteriorate, so either case is not preferable.

Next, the aforementioned emulsion polymer (B), which is the other main component of the composition of the present invention, will be described. The theoretical glass transition temperature (Tg
) must be within the range of 20 to 50°C.

[0016] If the temperature is lower than 20°C, the hardness of the film obtained will inevitably not reach the desired range, and as a result, not only will the drying properties of the composition decrease, but the film will also be easily softened by heat, and its anticorrosion properties will also decrease. This is not desirable because it means doing so.

[0017] More preferably, this Tg is 25 to 45
It is appropriate to use one within the range of ℃. In addition, the smaller the average particle diameter of the emulsion polymer (B), the better the film forming properties and the corrosion resistance of the coating film, but on the other hand, the evaporation of water etc. during the drying process of the composition is reduced, and , the drying property decreases.

[0018] Therefore, in consideration of the drying properties and anti-corrosion properties of the composition, the average particle diameter should be 0.04 to 0.04.
0.15 μm, more preferably 0.04 to 0.1
It is appropriate that the thickness be within a range of 0 μm.

Generally, commercially available emulsion polymers use a persulfate such as ammonia persulfate, sodium persulfate or potassium persulfate as a polymerization initiator in preparing the emulsion polymer. However, if these polymerization initiators are used, sulfates will be included in the emulsion polymer as a decomposition component, and these sulfates will also impair the corrosion resistance of the resulting film, so it is not preferable. .

For this purpose, such polymerization initiators include benzoyl peroxide, di-tert-butyl peroxide, tert-butyl perbenzoate, and tert-butyl peroxide.
Organic peroxides such as butyl octoate or acetyl peroxide; or hydrogen peroxide are particularly preferred examples, and it goes without saying that these may be used alone or in combination of two or more.

As for the polymer composition of the emulsion polymer (B), it is desirable to use acrylic or acrylic styrene in consideration of the anticorrosion properties of the film and the ease of designing the emulsion polymer.

Furthermore, it is desirable to use acrylic styrene. The higher the acid value of the emulsion polymer, the better the adhesion of the film to the substrate, which is preferable; however, if it is too high, the water resistance of the resulting film will decrease, so a higher acid value is preferred. Therefore, based on these considerations, the unsaturated carboxylic acid is copolymerized in a range of 4 to 10% by weight, more preferably 4 to 8% by weight, based on the total monomers. It is preferable to use emulsion polymers in the form of

Although there is no particular limit to the amount of emulsifier used in the preparation of the emulsion polymer (B), considering the water resistance and anticorrosion properties of the resulting film, the total amount of monomers used in the emulsion polymerization may vary. A suitable range is 0.2 to 4% by weight of the body.

During emulsion polymerization, known and commonly used reactive emulsifiers,
There is no particular problem in using a chain transfer agent or a crosslinking agent. The aqueous coating composition of the present invention each comprises:
Alkyd resin or its derivative (A) in solid content of 10
~40% by weight and emulsion polymer (B) with a solid content of 90~
60% by weight (total 100% by weight), and if the amount of component (A) used is less than 10% by weight, the resulting film will inevitably have poor corrosion resistance. On the other hand, if the amount of component (A) used is too large, exceeding 40% by weight, the drying properties will be reduced, which is not preferable in either case.

[0025]Although it is preferable to use pigments in order to improve the hardness and appearance of the coating film, as well as its drying properties and hiding properties, the amount used should be determined based on the corrosion resistance of the coating film. More preferably, the amount is such that the pigment weight concentration (PWC) is 60% or less.

Further, the use of anti-rust pigments is particularly preferable in order to improve the drying properties and anti-corrosion properties of the coating film, and the amount used is 0.1 to 2 in terms of pigment weight concentration (PWC).
A range of 0% is appropriate.

[0027] Such rust-preventing pigments may be those commonly known and commonly used, and among them, only representative ones include basic lead chromate, zinc chromate, strontium chromate, and barium chromate. various chromate compounds such as; various lead-based compounds such as calcium leadate, red lead or lead cyanamide;

[
Various phosphate-based compounds such as zinc phosphate, aluminum tripolyphosphate or zinc phosphite; Various molybdate-based compounds such as basic zinc molybdate or calcium molybdate; barium metaborate, calcium metaborate or Various borate compounds such as calcium borosilicate;

Mica-like iron oxide (MIO) or general formula MeO.Fe2O
3 ......[I] (However, Me in the formula
represents a divalent metal atom such as Ca, Sr, Ba, Mg, Zn or Mn. ) various iron oxide compounds such as magnetic ferrite; or zinc tungstate or calcium tungstate;
Various basic tungstate compounds, etc., and these can be used alone or in combination of two or more types.
Of course.

[0030] The composition of the present invention may contain known and commonly used pigment dispersants, antisettling agents, thickeners, thixotropic agents,
Various additives such as antifoaming agents, dryers, curing agents, solvents, film forming aids, and leveling agents can be added to form paints.

The aqueous coating composition of the present invention thus obtained, particularly the aqueous anticorrosive coating composition, can be used particularly as a factory coating agent for large steel plates such as architectural steel materials and springs, and processed materials thereof, or as a coating agent for cast iron pipes or pulleys. It can be applied and used as a factory coating agent for large base materials such as castings and processed materials thereof.

[0032]

[Example] Next, the present invention will be explained in more detail with reference examples, examples, comparative examples, applied examples, and comparative applied examples. Unless otherwise specified, all parts and percentages are based on weight. Assume that there is.

Reference Example 1 [Preparation Example of Emulsion Polymer (A)] "Hitenol N-08" was placed in a stainless steel reaction vessel equipped with a stirrer, reflux condenser, dropping funnel, thermometer and nitrogen gas introduction tube. 1.3 parts of [anionic emulsifier manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd.], "Neugen EA-14"
2" (nonionic emulsifier made by the same company), 0.2 parts of sodium styrene sulfonate (reactive emulsifier), and 130 parts of ion-exchanged water, and
The temperature was raised to ℃.

Next, a monomer mixture consisting of 35 parts of n-butyl acrylate, 60 parts of styrene, and 5 parts of methacrylic acid and 10 parts of ion-exchanged water were mixed with "hytenol".
0.2 parts of "N-08", 0.5 parts of tert-butyl hydroperoxide, and 0.3 parts of sodium bisulfite.
A mixture of the following components was added dropwise over a period of 3 hours.

Thereafter, the same temperature was maintained for 2 hours to complete the reaction. Thereafter, the mixture was cooled to room temperature, and the pH was adjusted to 8.5 and the solid content to 40% with 14% aqueous ammonia and water.

The emulsion polymer thus obtained had an average particle diameter of 0.05 μm (measured with a submicron analyzer) and a theoretical Tg of 34°C. Hereinafter, this will be abbreviated as EM-1.

Reference Examples 2 to 7 Emulsion polymers ( EM-2, 3 and 4) and control emulsion polymers (EM'-1, 2 and 3) were prepared.

[0038]

[Table 1]

Examples 1 to 8 and Comparative Example 1 Various aqueous coating compositions were obtained using the respective emulsion polymers thus obtained and water-dispersible alkyd resins.

However, only Comparative Example 1 did not use any emulsion polymer.

Application examples 1 to 8 and comparative application examples
1 obtained in Examples 1 to 8 and Comparative Examples 1 and 2,
Various water-based anticorrosive paints were obtained using the respective water-based coating compositions.

[0042] For pigment dispersion at this time, a millbase is prepared using the entire amount of the water-dispersible alkyd resin, and then let down with an emulsion polymer that has been plasticized with a film-forming agent in advance. I did it like that. A basic formulation example is shown below.
The recipe is shown in Table 2.

Paint formulation “Watersol CD-540” or “Watersol CD-520” 50 parts (solid content 20 parts) “MA-100” [Carbon black manufactured by Mitsubishi Chemical Industries, Ltd.] 3 parts “Homocal D ” [Charcoal manufactured by Shiroishi Sangyo Co., Ltd.
Calcium acid]
29 parts "PW-2" [phosphorus manufactured by Kikuchi Color Co., Ltd.
Zinc acid rust preventive pigment] 3 parts
SN Day Former 373” [Sannop
Antifoaming agent manufactured by Ko Co., Ltd.]
0.2 part ────────────
────────────────────────

Disperse the above using a sand mill

Emulsion polymer*
228 parts (solid content 80
Department) “Deitkunate 3111 [Dainippon Ink Kagaku
Gakkogyo Co., Ltd.
dryer]
Part 2 "Boncourt 3750" (thickened product manufactured by the same company)
agent) 0.
Part 2 Water
0～
10 parts triethylamine
0.2 parts
──────────────────────────
──────────
Stir the above
WC; 26% solid content; 42±1%

[0045] However, "Watersol CD-5
"40" is a vinyl-modified epoxy ester resin aqueous dispersion manufactured by the same company, with a solid content of 40% and a solid content acid value of 40.

[0046] Also, "Watersol CD-52
0" is an alkyd resin aqueous dispersion manufactured by the same company,
The solid content is 40% and the solid content acid value is 13.

*For the emulsion polymer, 4 parts of butyl cellosolve, 4 parts of Texanol, and 6.3 parts of water were added to 100 parts, and the solid content was adjusted to 35% by stirring uniformly. used.

[0048] Next, the respective water-based anticorrosive paints thus obtained were subjected to a comparative test for drying properties and anticorrosion properties according to the procedure described below.

[0049] Applied test method Drying property: (normal drying) An untreated dull steel plate (manufactured by Nippon Test Panel Co., Ltd.) was dried at 20°C.
And, under the condition of 65% RH, each paint was 1.
Applied with a 5 mil applicator.

Immediately after application, the test was started, and the drying time was measured by touch, and this was indicated. Drying properties: (heat drying) The above steel plates were preheated to a plate temperature of 80° C., and each paint was applied using a 1.5 mil applicator.

Thereafter, the sample was left in an atmosphere of 20° C. and 65% RH and measured in the same manner as above. Corrosion resistance: (dry) Each paint was applied to the above steel plate to a dry film thickness of 20±1
Apply to a thickness of μm at 20℃ and 65% RH.
It was left to dry under an atmosphere of 7 days.

[0052] After that, each coated surface was cross-cut with a cutter knife, and back sealing was applied to the areas other than the coated surface, and then the coated plate was placed in a salt spray tester and the test was conducted for a predetermined period of time.

Corrosion resistance: (Heat drying) In the same manner as above, each paint was applied so that the dry film thickness was 20 ± 1 μm, and it was dried for 20 minutes in an atmosphere of 80°C.
After heating and drying for a minute, at 20℃ and 65%
It was left to dry in an RH atmosphere for 7 days. Thereafter, the test was conducted in the same manner as above. The results of those applied tests are summarized in Table 2.

[0054]

[Table 2]

[0055]

Effects of the Invention As is clear from the above results, the aqueous coating composition of the present invention has excellent drying properties and anticorrosion properties in both cases of air drying and heat drying.
It can be said that it is extremely useful.

Claims (7)

[Claims] Claim 1: An alkyd resin or a derivative thereof (A);
An aqueous coating composition comprising an emulsion polymer (B) as an essential component. Claim 2: An alkyd resin or a derivative thereof (A);
An aqueous coating composition comprising an emulsion polymer (B) and a pigment (C) as essential components. 3. 10 to 40% by weight of an alkyd resin or a derivative thereof (A) having a solid content acid value of 10 to 50, and a theoretical glass transition temperature of 20 to 50°C.
and contains 90 to 60% by weight of an emulsion polymer (B) having an average particle diameter of 0.04 to 0.15 microns, and further contains a pigment if necessary. An aqueous coating composition characterized by: 4. The above-mentioned alkyd resin or derivative thereof (
Claim 1, wherein A) is an epoxy ester-based aqueous dispersion.
3. The aqueous coating composition according to any one of . 5. The emulsion polymer (B) described above is polymerized using an organic peroxide as a polymerization initiator, and contains 4 to 10% by weight of an unsaturated carboxylic acid based on the total amount of monomers. 4. Aqueous coating composition according to claim 1, which is a polymerized acrylic or acrylic styrenic emulsion polymer. 6. The aqueous anticorrosive coating composition according to claim 2 or 3, wherein the pigment (C) is a rust preventive pigment. 7. Claims 2 and 3, wherein the pigment (C) is contained in a pigment weight concentration of 0.1 to 20%.
or 6. The aqueous anticorrosive coating composition according to 6.