JP2002138255A - Water-based coating material composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a water-based coating material composition which excels in the storage stability of the coating material and also excels in the stain resistance, weatherability, and the like, of a coating film formed. SOLUTION: A synthetic resin emulsion having a reactive silyl group is used as the binder, and the electric conductivity of the entire coating material is set at <=2.5 mS/cm. It is preferred that the ratio of the remaining amount of silica in the synthetic resin emulsion is 0.1-30 wt.%. An anionic dispersing agent having an electric conductivity at a concentration of 10 wt.% of <=5 mS/cm is preferably used as the pigment dispersing agent.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention can be used for surface finishing of various materials such as metal, glass, porcelain tile, concrete, siding board, extruded plate, plastic and the like, and is mainly used for buildings and civil engineering structures. And the like.

[0002]

2. Description of the Related Art In recent years, in the field of paints used for architectural and civil engineering structures, a shift from a solvent-based paint using an organic solvent as a solvent to a water-based paint using water as a solvent is being made. This is to reduce the health hazards for painters and residents,
It is carried out for the purpose of reducing atmospheric environmental pollution, and is becoming more and more aqueous every year.

[0003] However, a coating film formed by a water-based paint generally tends to be inferior in stain resistance, weather resistance, and the like as compared with a coating film formed by a solvent-based paint. ing. In particular, regarding the stain resistance, it is often difficult to remove the stain from the coating film surface once the contaminant adheres, because the coating hardness of the water-based paint is low and the contaminant easily penetrates. . Such a problem is remarkable in an urban area or a suburb where oily contaminants are floating in the air due to exhaust gas from automobiles and the like, and is a factor that greatly impairs the aesthetics of the coating film. .

[0004] One of the techniques for improving the stain resistance and weather resistance of such a water-based paint is to impart a crosslinking property by introducing a silicon component. In this method, a reactive silyl group-containing compound is introduced into a synthetic resin emulsion, and the functional groups are reacted with each other to improve the coating properties such as stain resistance and weather resistance of the formed coating film. It is. In this method, by increasing the proportion of the silicon component, the crosslinkability can be increased, and the physical properties of the coating film can be improved. However, with the increase in the amount of the silicon component, the remaining reactive silyl groups react with each other during storage, causing a problem that the paint becomes unstable, such as causing a significant increase in viscosity.

[0005]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and is an aqueous coating composition which is excellent in storage stability of a coating composition and excellent in stain resistance and weather resistance of a formed coating film. Is to obtain a composition.

[0006]

Means for Solving the Problems In order to solve these problems, the present inventors have conducted intensive studies. As a result, in a paint using a reactive silyl group-containing synthetic resin emulsion as a binder, the electric conductivity of the entire paint is considered. The inventors have found that a coating composition having a specific degree is effective, and have completed the present invention.

That is, the present invention provides the following aqueous coating composition.

[0008] 1. A synthetic resin emulsion having a reactive silyl group is used as a binder, and the electric conductivity of the entire coating material is 2.5.
An aqueous coating composition having a mS / cm or less. 2. (A) A synthetic resin emulsion having a reactive silyl group and having a silica remaining amount ratio of 0.1 to 30% by weight is used as a binder, and the electric conductivity of the entire coating material is 2.5 mS / cm or less. An aqueous coating composition characterized by the following. 3. (A) 1 to 1000 parts by weight of a pigment (B), 100 parts by weight of a solid content of a synthetic resin emulsion having a reactive silyl group and a silica residual ratio of 0.1 to 30% by weight; 5) an electric conductivity of 5 m at a concentration of 10% by weight
An aqueous coating composition comprising 0.01 to 20 parts by weight of an anionic dispersant of S / cm or less, and having an electric conductivity of 2.5 mS / cm or less as a whole of the coating.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail along with its embodiments.

(A) Synthetic Resin Emulsion The component (A) in the composition of the present invention is a synthetic resin emulsion having a reactive silyl group and serves as a binder. This component (A) is a synthetic resin emulsion having good weather resistance, stain resistance, yellowing resistance, water resistance, chemical resistance and the like, and (a) a reactive silyl group-containing compound (hereinafter referred to as “component a”). ) As an essential component.

In the component (A), the method of introducing the component a is not particularly limited, and various methods can be adopted. For example, a method of copolymerizing a reactive silyl group-containing vinyl monomer. A method of reacting a silane compound after copolymerizing a reactive silyl group-containing vinyl monomer; a method of reacting a functional group in a resin with a coupling agent having a functional group capable of reacting with the functional group; A method of reacting a silane compound after reacting a functional group therein with a coupling agent having a functional group capable of reacting with the functional group, and the like.

As the reactive silyl group, an alkoxyl group, a phenoxy group, a mercapto group, an amino group,
Halogen, hydrogen atom, etc. are bonded.

The vinyl monomer having a reactive silyl group is a compound containing a reactive silyl group and a polymerizable double bond. Examples of the vinyl monomer include a vinyltrimethoxysilane, a vinyltriethoxysilane, and a vinyltri-n. -Butoxysilane, vinyl tris (β-methoxyethoxy)
Silane, allyltrimethoxysilane, trimethoxysilylethyl vinyl ether, triethoxysilylethyl vinyl ether, trimethoxysilylpropyl vinyl ether, triethoxysilylpropyl vinyl ether, γ
-(Meth) acryloyloxypropyltrimethoxysilane, γ- (meth) acryloyloxypropyltriethoxysilane, γ- (meth) acryloyloxypropylmethyldimethoxysilane, vinylmethyldimethoxysilane, methyldimethoxysilylethyl vinyl ether,
Methyl dimethoxysilylpropyl vinyl ether and the like can be mentioned, and one or more of these can be used.

As the silane compound described above, those having two or more reactive silyl groups in one molecule are used. For example, tetrafunctional alkoxysilanes such as tetraethoxysilane, tetramethoxysilane and tetrabutoxysilane; methyl Trimethoxysilane, methyltriethoxysilane, methyltributoxysilane, ethyltrimethoxysilane, ethyltriethoxysilane, ethyltributoxysilane, propyltrimethoxysilane, propyltriethoxysilane, butyltrimethoxysilane, butyltriethoxysilane, phenyl Trifunctional alkoxysilanes such as trimethoxysilane, phenyltriethoxysilane, phenyltributoxysilane; dimethyldimethoxysilane, dimethyldiethoxysilane, dimethyldibutoxysilane, diethyldisilane Toxysilane, diethyldiethoxysilane, dipropyldimethoxysilane, dipropyldiethoxysilane, dibutyldimethoxysilane, dibutyldiethoxysilane, diphenyldimethoxysilane, diphenyldiethoxysilane, diphenyldibutoxysilane, methylphenyldimethoxysilane, methylphenyldiethoxy Bifunctional alkoxysilanes such as silane; tetrachlorosilane, methyltrichlorosilane, ethyltrichlorosilane, propyltrichlorosilane, phenyltrichlorosilane, vinyltrichlorosilane, dimethyldichlorosilane, diethyldichlorosilane, diphenyldichlorosilane, methylphenyldichlorosilane, etc. Chlorosilanes: tetraacetoxysilane, methyltriacetoxysilane, phenyltriacetoxy Orchids, dimethyldiacetoxysilane, such as acetoxy silanes such as diphenyl diacetoxy silane and the like, can be used one or two or more thereof. Further, a compound having one reactive silyl group in one molecule can be used in combination.

Examples of the combination of the functional groups include a hydroxyl group and an isocyanate group, an amino group and an isocyanate group, a carboxyl group and an epoxy group, an amino group and an epoxy group, and an alkoxysilyl group. The coupling agent is, for example, a compound having at least one or more reactive silyl groups and other substituents in one molecule. Specifically, β- (3,4 epoxycyclohexyl) ethyltrimethoxysilane Γ-glycidoxypropylmethyldiethoxysilane, γ-glycidoxypropyltriethoxysilane, N- (β-aminoethyl)
-Γ-aminopropylmethyldimethoxysilane, N-
(Β-aminoethyl) -γ-aminopropyltrimethoxysilane, γ-aminopropyltrimethoxysilane, γ
-Aminopropyltriethoxysilane, isocyanate-functional silane and the like, and one or more of these can be used.

The weight ratio of the component a in the component (A) is as follows:
The silica residual ratio in the resin solid content of the component (A) is 0.1 to
It is preferably 30% by weight, more preferably 1 to 10% by weight. When the silica remaining ratio is more than 30% by weight, it becomes difficult to ensure storage stability.
If the amount is less than 0.1% by weight, the effect of improving the properties of the coating film such as stain resistance and weather resistance cannot be sufficiently exhibited.

The ratio of the remaining amount of silica is expressed in terms of the weight remaining after being completely hydrolyzed and baked at 900 ° C. into silica (SiO ₂ ) after the compound having a Si—O bond. Things. In general, alkoxysilane, silicate, and the like have a property of reacting with water to cause a hydrolysis reaction to form silanol, and to cause a condensation reaction between silanols or silanol and alkoxy. When this reaction is performed to the ultimate, silica (SiO ₂ ) is obtained.
These reactions are represented by the general formula: RO (Si (OR) ₂ O) _n R + (n + 1) H ₂ O → n
It is represented by a reaction formula of SiO ₂ + (2n + 2) ROH, and is obtained by converting the amount of the remaining silica component based on the reaction formula.

The copolymerizable monomer of the component (A) is not particularly limited, but an acrylic monomer can be suitably used. Examples of the acrylic monomer include methyl (meth) acrylate, ethyl (meth) acrylate, n-butyl (meth) acrylate, i-butyl (meth) acrylate, and 2-ethylhexyl (meth).
Alkyl-containing (meth) acrylic monomers such as acrylate and cyclohexyl (meth) acrylate; hydroxyl-containing (meth) acrylic monomers such as 2-hydroxyethyl (meth) acrylate; ethylene such as (meth) acrylic acid Unsaturated carboxylic acids; Amino group-containing (meth) acrylic monomers such as dimethylaminoethyl (meth) acrylate and dimethylaminopropyl (meth) acrylate; and amides such as (meth) acrylamide and ethyl (meth) acrylamide ( (Meth) acrylic monomers; nitrile group-containing (meth) acrylic monomers such as acrylonitrile; and epoxy group-containing (meth) acrylic monomers such as glycidyl (meth) acrylate.

In the component (A), in addition to the above monomers, aromatic hydrocarbon vinyl monomers such as styrene, methylstyrene, chlorostyrene, and vinyltoluene; maleic acid, itaconic acid, crotonic acid, fumaric acid, Α, β-ethylenically unsaturated carboxylic acids such as citraconic acid; sulfonic acid-containing vinyl monomers such as styrene sulfonic acid and vinyl sulfonic acid; acid anhydrides such as maleic anhydride and itaconic anhydride; vinyl chloride, vinylidene chloride , Chloroprene and other chlorine-containing monomers; hydroxyethyl vinyl ether, hydroxypropyl vinyl ether and other hydroxyl-containing alkyl vinyl ethers; ethylene glycol monoallyl ether, propylene glycol monoallyl ether and diethylene glycol monoallyl ether; alkylene glycols Α-olefins such as ethylene, propylene and isobutylene; vinyl esters such as vinyl acetate, vinyl propionate, vinyl butyrate and vinyl pivalate; vinyl ethers such as methyl vinyl ether, ethyl vinyl ether, butyl vinyl ether and cyclohexyl vinyl ether; ethyl allyl Allyl ethers such as ether and butyl allyl ether can also be used. In addition, an ultraviolet absorber containing an ethylenically unsaturated double bond, a light stabilizer containing an ethylenically unsaturated double bond, and the like can also be used.

The emulsifier used for the polymerization is appropriately selected from anionic, cationic, nonionic, amphoteric, nonionic-cationic, nonionic-anionic, non-reactive, and reactive. They can be used alone or in combination.

As the polymerization initiator, ordinary radical initiators can be used, such as persulfates such as ammonium persulfate, a redox initiator comprising a combination of hydrogen peroxide and sodium hydrogen sulfite, Examples thereof include a system in which an inorganic initiator such as iron salt and silver nitrate is mixed, or a dibasic acid peroxide such as disuccinic peroxide and diglutaric peroxide; and an organic initiator such as azobisbutyronitrile. The amount of the polymerization initiator is usually 0.01 to 100 parts by weight of the monomer.
It is about 5 parts by weight.

The weight average molecular weight of the component (A) is 30,000
More preferably, it is more preferably 50,000 or more.
When the molecular weight is 30,000 or more, stain resistance,
Weather resistance, water resistance and the like can be improved. Also,
The glass transition temperature of the component (A) is preferably from -20 to 80C. When the glass transition temperature is lower than −20 ° C., the stain resistance tends to decrease, and when the glass transition temperature is higher than 80 ° C., the coating film is liable to crack.

(B) Pigment The component (B) is used as a coloring agent, a bulking agent, or a gloss adjusting agent.
It also provides effects such as improvement in coating film strength. Specifically, they are classified into inorganic color pigments, organic color pigments, and extender pigments.

Examples of inorganic color pigments include titanium oxide, carbon black, ferric oxide (red iron oxide), yellow iron oxide, ocher, ultramarine, cobalt green, and the like. Examples of organic color pigments include, for example, azo type, Naphthol,
Pyrazolone, anthraquinone, perylene, quinacridone, disazo, isoindolinone, benzimidazole, phthalocyanine, quinophthalone and the like can be used. As the extender pigment, for example, heavy calcium carbonate, clay, kaolin, talc, precipitated barium sulfate, barium carbonate and the like can be used.

The content of the component (B) is preferably from 1 to 1,000 parts by weight, more preferably from 5 to 600 parts by weight, based on 100 parts by weight of the solid content of the component (A). In particular, when the amount is 5 to 100 parts by weight, a glossy coating film can be obtained. When the content of the component (B) is less than 1 part by weight, sufficient coloring effect, increasing effect, gloss adjusting effect, and the like cannot be obtained. If it is more than 1000 parts by weight, cracks are likely to occur during film formation.

(C) Pigment Dispersant The component (B) which acts as a pigment dispersant of the component (B) has an electric conductivity of 5 mS / at a concentration of 10% by weight.
cm or less, preferably 1 mS / cm or less. When the electric conductivity has such a value, when the composition of the present invention contains the pigment (B), storage stability and high gloss in a glossy paint can be ensured.

In the component (C), examples of the group imparting anionic properties include carboxylate, sulfate, sulfonate, phosphate and the like.

As the skeleton composition of the component (C), various types can be used, and examples thereof include those having an alkylene oxide such as methylene oxide, ethylene oxide, propylene oxide, and butylene oxide.

The acid value of the component (C) is 2 to 100 KOHm
g / g is desirable. Acid value is 2KOHmg / g
If it is smaller, it is difficult to obtain sufficient dispersibility. 100 KO
If it is higher than Hmg / g, the water resistance of the coating film may decrease, and the storage stability may decrease.

The content of the component (C) is 0.01 to 20 parts by weight, preferably 0.1 to 10 parts by weight, based on 100 parts by weight of the solid content of the component (A). When the content of the component (C) is less than 0.01 part by weight, sufficient pigment dispersibility,
It becomes difficult to ensure storage stability. If the amount is more than 20 parts by weight, weather resistance, water resistance and the like will be reduced.

In the composition of the present invention, in addition to the above-mentioned components, a plasticizer, a film-forming auxiliary, an antifreezing agent, an antiseptic and a fungicide, which are usually used in paints, if necessary, so as not to affect the present invention. ,
Additives such as defoaming agents, thickeners, leveling agents, pH adjusters, pigment dispersants, anti-settling agents, anti-sagging agents, matting agents, ultraviolet absorbers, light stabilizers, and antioxidants, alone or in combination It can also be blended. When blending such additives, care must be taken so that the electrical conductivity of the entire coating does not exceed the value specified in the present invention.

The composition of the present invention contains the above-mentioned component (A) as an essential component. In the case of performing coloring, gloss adjustment, etc., in addition to the component (A), the component (B) and the component (C) It contains components. In the composition of the present invention, the final electric conductivity of the entire coating composition is 2.5 mS / cm or less, preferably 2.3 mS / cm or less, more preferably 2.0 mS / cm or less.
Adjust to S / cm or less. In general, in coatings using a reactive silyl group-containing synthetic resin emulsion, increasing the amount of the silicon component improves the coating properties such as stain resistance and weather resistance, but on the other hand, the storage stability of the coating. Is difficult to secure. According to the present invention, even when the amount of the silicon component is large, the electric conductivity is adjusted within the above-mentioned range, whereby sufficient storage stability is ensured, and contamination resistance and weather resistance are improved. A coating film excellent in such properties can be obtained. When the composition of the present invention contains a pigment, the pigment dispersant has an electric conductivity of 5 m at a concentration of 10% by weight.
By using an anionic dispersant of S / cm or less,
Not only storage stability, but also high gloss with a glossy paint can be ensured. Although the mechanism of action of the present invention is not clear, the reaction between the reactive silyl groups in the component (A) can be appropriately controlled by setting the electric conductivity of the entire paint and the electric conductivity of the pigment dispersant to specific values. , It is assumed that the above-described effect can be exerted.

The composition of the present invention can be used for metal, glass, porcelain tile, concrete, siding board, extruded board,
It can be used for surface finishing of various materials such as plastic, and is mainly used for protection of buildings such as buildings and civil engineering structures. At this time, the aqueous coating composition of the present invention comprises:
It is applied to the final surface and can be applied directly to the substrate, or some surface treatment (sealer,
It is also possible to apply the coating after applying a surface treatment such as a surfacer, a filler or the like), but the coating is not particularly limited. As a coating method, it can be applied by various methods such as brush coating, spray coating, roller coating, roll coater and flow coater. Further, the surface of the building material can be pre-coated at a factory or the like.

[0034]

EXAMPLES Examples and comparative examples are shown below to further clarify the features of the present invention.

[Preparation of paint] Using the raw materials shown in Table 1, paints were prepared according to the formulations shown in Table 2, and each test was conducted. The electric conductivity was measured at 25 ° C. using “Model SC82 Personal SC Meter SC8221-J” (manufactured by Yokogawa Electric Corporation). In measuring the electric conductivity of the pigment dispersant, a pigment dispersant having a solid content adjusted to 10% by weight with distilled water was used.

[0036]

[Table 1]

[0037]

[Table 2]

[Test Method] Storage stability The prepared coating composition was stored in a thermostat at 50 ° C. for 14 days, and the change in viscosity was confirmed. The evaluation is as follows. ：: less than 10% change in viscosity △: 10% or more and less than 30% change in viscosity X: 30% or more change in viscosity

Specular glossiness The coating composition stored under the above conditions was subjected to 150 × 120 ×
An applicator was drawn on a 3 mm transparent glass plate so as to have a WET film thickness of 150 μm, dried and cured in a standard state for 48 hours, and then JIS K5400 7.6 (199)
According to 0), the gloss at an angle of 60 degrees was measured.

Accelerated contamination test SK # 100 was applied to an aluminum plate of 150 × 75 × 0.8 mm.
No. 0 primer (epoxy resin base coating material; manufactured by SK Kaken Co., Ltd.) was spray-coated so as to have a dry film thickness of 30 μm, dried under standard conditions for 8 hours, and then stored under the above conditions. A test piece was prepared by spray coating so that the dry film thickness became 40 μm. After the prepared test body was dried and cured in a standard state for 7 days, a 15% by weight aqueous dispersion of carbon black was applied to the coating film surface with a diameter of 20 m.
m and a height of 5 mm, and left in a constant temperature room at 20 ° C. for 24 hours. Thereafter, the film was washed in running water, and the degree of contamination on the coating film surface was visually evaluated. The evaluation is as follows. ◎: No trace is observed ○: Only slight trace is observed △: Trace is observed ×: Remarkable trace is observed

[Test Results]

[Table 3]

Table 3 shows the test results. Examples 1 to 4, which are the aqueous coating compositions of the present invention, are all excellent in storage stability, and in particular, Examples 1 to 3, in which the electric conductivity and the remaining silica ratio are within more preferable ranges, are accelerated contamination. The test also showed good results. In Comparative Examples 1 and 2, the electric conductivity of the whole paint was high, and the storage stability was poor.
Comparative Example 3 was a paint using a synthetic resin emulsion containing no reactive silyl group, and resulted in poor stain resistance.

[0043]

According to the present invention, it is possible to obtain an aqueous coating composition which is excellent in the storage stability of the coating and the stain resistance and weather resistance of the formed coating film. Further, since the composition of the present invention is a one-pack type, it is a material that can reduce the complexity of the coating operation.

Claims (3)

[Claims] A synthetic resin emulsion having a reactive silyl group is used as a binder, and the electric conductivity of the whole paint is 2.5 mS.
/ Cm or less. 2. A synthetic resin emulsion having a reactive silyl group and a residual silica ratio of 0.1 to 30% by weight is used as a binder, and the electric conductivity of the entire coating material is 2.5 mS.
/ Cm or less. 3. The pigment (B) is added in an amount of 1 to 100 parts by weight based on 100 parts by weight of the solid content of the synthetic resin emulsion (A) having a reactive silyl group and having a silica residual ratio of 0.1 to 30% by weight.
0 parts by weight, (C) an anionic dispersant having an electric conductivity of 5 mS / cm or less at a concentration of 10% by weight is 0.01 to 2 parts by weight.
0 parts by weight, and the electric conductivity of the whole paint is 2.5 mS /
cm or less.