JP2001040276A - Covering composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a covering composition excellent in adhesion, and properties to be impregnated into an inorganic building material and reinforcing the material, and also excellent in drying properties. SOLUTION: This covering composition can stick >=10 g silica powder per g solid resin, contains an aqueous resin dispersion capable of being diluted with isopropyl alcohol so as to have >=50% dilution ratio, and can form a coated membrane having <=30% water absorption. The aqueous resin dispersion preferably contains (A) a copolymer composed of (i) a carbonyl or aldehyde group-containing ethylenically unsaturated monomer unit, (ii) an ethylenically unsaturated carboxylic acid monomer unit, and (iii) an ethylenically unsaturated monomer unit except the components (i) and (ii), (B) a copolymer composed of (iv) a glycidyl group-containing ethylenically unsaturated monomer unit and (v) an ethylenically unsaturated monomer unit except the component (iv), regulated so that the ratio of the molar number of glycidyl groups in the copolymer B to the molar number of carboxyl groups in the copolymer A may be 0.1-0.6.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to an inorganic building material used for tiles, exterior materials and the like, which is excellent in adhesion and impregnation reinforcement.
Furthermore, the present invention relates to a coating composition having excellent drying properties, and can be suitably used particularly for inorganic building material undercoating applications.

[0002]

2. Description of the Related Art As a method of forming a tough resin coating film on the surface of an inorganic building material using an aqueous paint, for example, Japanese Patent Publication No. Sho 4
JP-A-4-21554 describes the use of a mixture of an ordinary resin dispersion having a large particle diameter and a resin dispersion having an adhesive small particle diameter having a polar group.
No. 187 discloses a fine particle diameter (0.02 μm to 0.02 μm).
8 μm) It is described that a resin dispersion liquid is used and penetrated into a base material. JP-A-10-46051 describes that the average particle diameter of a large particle diameter resin and the average particle diameter of a small particle diameter resin are defined. It is described to use those which define the mixing ratio of these. Also, JP-A-5-247376
Japanese Patent Application Laid-Open No. 8-13923 discloses that an aqueous resin in which a specific resin is solubilized is used. Further, Japanese Patent Publication No. 8-13923 discloses that a carbonyl group-containing copolymer is added by alkali addition. It describes that a water-soluble copolymer obtained by emulsion polymerization of a water-soluble copolymer is used as a dispersant.

[0003]

However, the water-based paints disclosed in these prior arts tend to have poor drying properties. For example, when used as an undercoat water-based paint for inorganic building materials, It often took a long time before the top coat could be applied.

[0004] As a method of improving the drying property of the water-based paint,
It is known to add low-boiling alcohols represented by methanol, ethanol and isopropyl alcohol. However, the water-based paint disclosed in the above-mentioned prior art has a low alcohol shock resistance, so when a low-boiling alcohol is added thereto, the dispersion stability of the paint is reduced, and the resin component is agglomerated. Had the problem that

[0005] Further, coating films formed from these water-based paints generally have low water resistance. For example, if the coating film is exposed to the weather for a long period of time, blisters and peeling are likely to occur in the coating film. Penetrates through the coating film and penetrates the base material, and when this moisture freezes in winter or the like, the base material expands, and the coating film and the base material are destroyed, which may cause a practical problem.

[0006]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies to solve the above-mentioned problems. As a result, the present inventors have found that an aqueous resin dispersion having a specific range of adhesiveness to silica powder and dilutability with isopropyl alcohol is contained. And the coating composition having a specific range of water absorption of the formed coating film is excellent in drying property, adhesion to inorganic building materials, excellent in impregnation reinforcing property, and a coating film excellent in water resistance. The present invention was found to be able to provide a water-based paint suitable for use as a primer for inorganic building materials, and completed the present invention.

[0007] That is, the present invention relates to 10
This is a coating composition capable of adhering silica powder of at least g and containing an aqueous resin dispersion liquid dilutable with isopropyl alcohol by 50% or more, and forming a coating film having a water absorption of 30% or less.

[0008]

DETAILED DESCRIPTION OF THE INVENTION The aqueous resin dispersion used in the present invention must be capable of adhering 10 g or more of silica powder per 1 g of resin solids. Thereby, sufficient impregnation reinforcing property with respect to the inorganic building material can be imparted to the coating film.

[0009] The silica powder here is a common name for silicon dioxide, which is sand mainly composed of quartz grains, and has a chemical composition of S
It is made of iO ₂ .

[0010] The adhesion amount of silica powder per 1 g of resin solid content is 10
If it is less than g, the impregnation reinforcing property becomes insufficient, which is not preferable from the viewpoint of the adhesion of the coating film and the water resistance. Preferably 1
It is 1 g or more, more preferably 12 g or more.

[0011] The aqueous resin dispersion used in the present invention comprises:
It must be dilutable with isopropyl alcohol at a dilution ratio of 50% or more. Thereby, by further adding a low boiling point alcohol or the like to the aqueous resin dispersion,
It is possible to achieve both the drying property and the stability of the obtained coating composition.

[0012] The term "dilution ratio" as used herein refers to the value of the mass of the added isopropyl alcohol in the coating composition obtained by further adding isopropyl alcohol to the aqueous resin dispersion used in the present invention. Is the value (percent) divided by the value of the mass of the aqueous resin dispersion to be prepared. The term "dilutable" refers to a state in which no aggregate is present in the coating composition diluted with isopropyl alcohol.

[0013] If the dilutable range with isopropyl alcohol is less than 50%, the drying property at the time of coating decreases, and the time required to proceed to the next step of coating an intermediate coating paint or the like becomes undesirably long. More preferably, it is at least 53%, even more preferably at least 55%.

Further, in the coating composition of the present invention, the water absorption of the formed coating film must be 30% or less. Thereby, excellent water resistance can be imparted to the coating film. If the water absorption exceeds 30%, the amount of water that passes through the coating film and is absorbed by the substrate increases, and the absorbed water may break the substrate by repeated freezing and thawing, which is not preferable. . More preferably, it is 25% or less, still more preferably 20% or less.

The aqueous resin dispersion used in the present invention includes a carbonyl or aldehyde group-containing ethylenically unsaturated monomer unit (), an ethylenically unsaturated carboxylic acid monomer unit (), and units and other ethylene units. (A) composed of an unsaturated monomer unit (), a glycidyl group-containing ethylenically unsaturated monomer unit (), and an ethylenically unsaturated monomer unit () other than a unit. It is preferable that the copolymer (B) is blended.

By using such an aqueous resin dispersion, it is possible to obtain a coating composition having excellent (more) adhesion to various inorganic base materials, impregnation reinforcing property and water resistance.

From the viewpoint of blocking resistance and dispersion stability, the composition of the monomer unit constituting the copolymer (A) is 0.5 to 10% by mass, preferably 1 to 8% by mass. By having units equal to or greater than the lower limit, blocking resistance can be improved. Conversely, by having units equal to or less than the upper limit, the copolymer (A) can be used without impairing dispersion stability. ) Can be present. In addition, the unit is in the range of 5 to 20% by mass, preferably 5 to 18% by mass from the viewpoint of dispersion stability, and having units equal to or more than the lower limit allows the dispersion stability of the copolymer (A) to be improved. Conversely, by having a unit not more than the upper limit, a copolymer (A) having excellent dispersion stability can be obtained without causing significant viscosity increase during polymerization. . The unit is preferably in the range of 70 to 94.5% by mass, more preferably 74 to 94% by mass.

As the carbonyl group or aldehyde group-containing ethylenically unsaturated monomer unit () constituting the copolymer (A), there may be mentioned acrolein, diacetone (meth) acrylamide, formylstyrene and the like. it can.

[0019] Examples of the ethylenically unsaturated carboxylic acid monomer unit () constituting the copolymer (A) include units composed of acrylic acid, methacrylic acid, itaconic acid and the like.

Examples of the ethylenically unsaturated monomer unit () constituting the copolymer (A) include alkyl esters of acrylic acid or methacrylic acid having 1 to 18 carbon atoms, vinyl aromatic compounds, acrylonitrile, methacrylonitrile The unit consisting of, for example, can be appropriately selected as needed.

[0021] The molecular weight of the copolymer (A) is not particularly limited, but from the viewpoint of physical properties of the coating film, the weight average molecular weight is 500.
It is preferably 0 or more, and more preferably 8000 or more.

The composition of the monomer unit constituting the copolymer (B) is in the range of 0.5 to 20% by mass, preferably 1 to 15% by mass from the viewpoint of dispersion stability. Having a unit greater than or equal to the lower limit can form a chemical bond with the copolymer (A), and conversely, having units equal to or less than the upper limit, the dispersion stability of the copolymer (B) can be increased. This is preferable because polymerization can be performed without impairing the properties.

The unit is preferably in the range of 80 to 99.5% by mass, more preferably 85 to 99% by mass.

Examples of the glycidyl group-containing ethylenically unsaturated monomer unit () constituting the copolymer (B) include units composed of glycidyl acrylate, glycidyl methacrylate and the like.

Examples of the ethylenically unsaturated monomer unit () constituting the copolymer (B) include alkyl esters of acrylic acid or methacrylic acid having 1 to 18 carbon atoms, vinyl aromatic compounds, acrylonitrile, methacrylonitrile The unit composed of the above can be appropriately selected as needed.

The molecular weight of the copolymer (B) is not particularly limited, but is preferably 10,000 or more, more preferably 20,000 or more in terms of weight average molecular weight from the viewpoint of the properties of the obtained coating film.

When the copolymer (A) and the copolymer (B) in the above aqueous resin dispersion are chemically bonded, the dispersion stability of the coating composition of the present invention can be further improved. Further, the generation of agglomerates can be suppressed even when a low-boiling alcohol is added without impairing the adhesion to the substrate and the impregnation reinforcing property, and a coating composition having excellent drying properties can be obtained.

More specifically, it is preferable to react at least a part of the carboxyl group in the copolymer (A) with at least a part of the glycidyl group in the copolymer (B).

In this case, the ratio of the number of moles of glycidyl groups in the copolymer (B) to the number of moles of carboxyl groups in the copolymer (A) is preferably in the range of 0.1 to 0.6. . This is because a chemical bond between the copolymers (A) and (B) is sufficiently formed by setting the molar ratio to 0.1 or more, so that the generation of aggregates when dilution with isopropyl alcohol is performed. And the dispersion stability of the dispersion in which a chemical bond is formed between each of the copolymers (A) and (B) and between (A) and (B) by making the content 0.6 or less. This is because a necessary chemical bond between (A) and (B) can be formed without impairing the structure. More preferably,
It is in the range of 0.15 to 0.55.

The carboxyl group in the copolymer (A)
The fact that the acid value of the copolymer (A) decreases after blending with the copolymer (B) can be confirmed that the glycidyl group of the copolymer (B) is chemically bonded to the glycidyl group. Further, it can be easily confirmed by noting the change in the ester bond generated by the reaction between the carboxylic acid and the glycidyl group in the infrared absorption spectrum.

Further, it is formed by further adding a compound having two or more hydrazine residues to an aqueous resin dispersion containing the above-mentioned copolymer (A) and copolymer (B). The blocking resistance of the coating film can be improved. In this case, the ratio of the number of moles of the hydrazine residue in the aqueous resin dispersion to the number of moles of the carbonyl or aldehyde group (hydrazine residue / carbonyl group or aldehyde group) is in the range of 0.3 to 1.5. Preferably, there is. When the molar ratio is 0.3 or more, an improvement in blocking resistance tends to be recognized, and 1.5 or more.
This is because a stable performance is likely to be exhibited without impairing the transparency of the storage-stable clear coating film of the coating composition by the following. More preferably,
It is in the range of 0.5 to 1.2.

Examples of the compound having two or more hydrazine residues include adipic dihydrazide, isophthalic dihydrazide, and sebacic dihydrazide.

In the aqueous resin dispersion used in the present invention,
When the copolymer (A) and the copolymer (B) are contained, the glass transition temperature (Tg) of the copolymer (A) calculated from the Fox equation is determined by the copolymer (B). Is preferably higher than the value of This makes it possible to achieve both the blocking resistance and the substrate adhesion of the coating film formed from the coating composition of the present invention.

The Fox equation is represented by the following equation. 1 / Tg = Σ (1 / Tgi · wi) (where Tg represents Tg (K) of the copolymer, Tgi represents Tg (K) of the i-component homopolymer, and wi is the weight of the i-component. Represents the fraction.)

[0035] By this, it is used in a temperature range higher than the minimum film forming temperature of the coating film obtained from the coating composition of the present invention,
Even when it is necessary to overlap the coating films, there is an advantage that the coating films do not adhere to each other, and the minimum film forming temperature can be set low.

[0036] The method for producing the above-mentioned copolymer (A) can be appropriately selected as necessary, but is preferably produced by a suspension polymerization method. This is because, for example, when the copolymer (A) is produced by a solution polymerization method, when producing the aqueous resin dispersion used in the present invention, the copolymer (A) is removed by removing the solvent, Although a process such as replacing the solvent with water is required, the production by the suspension polymerization method makes it possible to directly obtain the copolymer (A) in an aqueous medium, so that such a process becomes unnecessary. It is.

Further, a copolymer (A) produced by a suspension polymerization method
By using, the water absorption of the coating film can be reduced to 30% or less without impairing the impregnation reinforcing property to the base material.

In the case of producing the copolymer (A) by the suspension polymerization method, a compound having a solubility in water of less than 0.1 (mass g soluble in 100 g of water) is used as a polymerization initiator. Is preferred from the viewpoint of polymerization stability.

Examples of the polymerization initiator having a solubility in water of less than 0.1 include azo-based polymerization initiators such as 2,2'-azobis-isobutyronitrile and 2,2'-azobis-methylbutyronitrile. And organic peroxide-based initiators such as benzoyl peroxide and lauroyl peroxide.

[0040] The method for producing the above-mentioned copolymer (B) can be appropriately selected as necessary, but is preferably produced by an emulsion polymerization method. By using the copolymer (B) produced by the emulsion polymerization method, a coating film having excellent durability can be formed.

The emulsion polymerization of the copolymer (B) can be carried out in the presence of the copolymer (A), and is particularly preferably carried out in an alkaline aqueous solution of the copolymer (A). In this case, when the copolymer (B) is polymerized, the copolymer (A)
And the chemical bond between the copolymer (B) and the copolymer (B) can be advanced, and the copolymer (A) and the copolymer (B) are separately prepared,
The productivity tends to be higher and the dispersion stability as an aqueous resin dispersion component tends to be improved as compared with the case where a chemical bond is formed between the copolymers (A) and (B) by blending.

When the copolymer (B) is produced by an emulsion polymerization method, it is preferable to use a compound having a solubility in water of 0.1 or more as a polymerization initiator from the viewpoint of polymerization stability.

Examples of the polymerization initiator having a solubility in water of 0.1 or more include persulfates such as sodium persulfate and ammonium persulfate, and organic peroxide initiators such as tertiary butyl hydroperoxide. Can be mentioned.

[0044] The coating composition of the present invention can be used both as a non-colored system and as a colored system, and is not particularly limited. The pigment or the like for coloring is not particularly limited, and a conventionally known pigment can be used. In addition, the coating composition of the present invention may be added with additives such as a plasticizer and a leveling agent and a thickener, and may be blended to control the workability as a coating material.

Since the coating composition of the present invention has excellent dispersion stability and good alcohol shock resistance, it is possible to add a low-boiling alcohol for the purpose of improving the drying property.

The method of applying the coating composition of the present invention is not particularly limited, and can be appropriately selected and applied as needed.

[0047]

The present invention will be described below in detail with reference to examples. Parts in the following description indicate parts by mass.

[0048] The copolymer numbers in Table 1 indicate the ethylenically unsaturated monomer compositions of the copolymer (A) and the copolymer (B). Examples 1 and 2 and Comparative Examples Examples 1 and 2 are examples in which the copolymers (A) and (B) are blended to obtain an aqueous resin dispersion.

Examples 3 to 5 and Comparative Examples 3 and 4 shown in Table 2 are the ethylenically unsaturated monomers constituting the copolymer (B) in an aqueous alkali solution of the copolymer (A). In this example, an aqueous resin dispersion is obtained by emulsion polymerization by dropping a mixture of the above and a radical polymerization initiator.

The adhesion to silica powder, the water absorption of the coating film, the resistance to alcohol shock, the drying property, and the blocking resistance were evaluated by the following methods.

(1) Adhesion to Silica Powder In a glass beaker having a diameter of about 80 mm, a height of about 100 mm and a thickness of about 2 mm, put silica powder (silica sand (10
１５15 mesh classified product) to about 10 mm from the opening, and 2 g of an aqueous resin dispersion having a solid content adjusted to 20% ± 1% is dropped. After the dropping, the mixture is left for 24 hours, taken out on a 16 stainless steel mesh, and only the silica powder adhered by the aqueous resin dispersion dropped on the mesh is separated. The separated silica powder is dried at 105 ° C. for 2 hours, and the dry weight is weighed. The dry weight is divided by the solid content of the aqueous resin dispersion used to calculate the amount of silica powder adhesion (g) per 1 g of the solid content of the aqueous resin dispersion.

(2) Water absorption of coating film The test was conducted in JIS-K5400 (General paint test method).
Where the temperature is 20 ± 1 ° C., the humidity is 73 ± 5%, and there is no direct sunlight. The aqueous resin dispersion is applied on an alkyd intermediate coated steel sheet so that the dry film thickness becomes about 50 μm, and dried at 80 ° C. for 3 hours. The dried coated plate is cooled to room temperature, and the weight (a) of the coating film alone is measured. The coated plate whose weight has been measured is immersed in warm water at 40 ° C. for 7 days. After a lapse of 7 days, the coated plate is taken out and only water droplets adhering to the coating film surface are gently wiped off, and the weight (b) of the coated plate is measured. After measuring the weight, the coated plate is dried at 50 ° C. for 8 hours, the weight (c) of the coated plate is measured again, and the water absorption of the coating film is calculated by the following formula. Water absorption (%) = ((b)-(c)) / (a) × 100

(3) Alcohol Shock Resistance Solid content is adjusted to 20 ± 1%, and a fixed amount of isopropyl alcohol is added to 100 g of an aqueous resin dispersion filtered through a 100-mesh stainless steel wire mesh, and a Waring blender 7010S (Waring, USA) Company)
After stirring at 00 rpm for 5 minutes, the mixture is left at 20 ° C. for 1 hour. After standing, it was taken out on a 100-mesh stainless steel wire mesh, dried in a dryer at 105 ° C. for 2 hours, and weighed.
The amount of agglomerates generated when isopropyl alcohol is added at a certain dilution rate is confirmed, and judgment is made based on the following criteria.

◎: Less than 0.1% by mass of aggregates ○: More than 0.1% by mass and less than 1% by mass of aggregates Δ: 1% by mass or more and less than 5% by mass of aggregates ×: 5% by mass of aggregates that's all

(4) Blocking resistance A 2 cm square gauze was placed on a painted plate prepared under the same conditions as in the measurement of the water absorption of the coating film, and two 500 g weights were placed thereon and placed at 50 ° C. And left for 24 hours. After 4 hours, take out from the dryer and leave it with the weight on it until it reaches room temperature. After confirming that the temperature of the coated plate is at room temperature, remove the weight, turn the coated plate upside down, and judge whether gauze falls without touching it with the following criteria.

A: The gauze falls without touching the hand, and no trace of the gauze remains on the coating film. ：: The gauze falls without touching the hand, but traces of the gauze remain on the coating film. Δ: The gauze drops when touched, but traces of the gauze remain on the coating film. X: It is difficult to remove the gauze from the coating film even by touching it.

(5) Substrate adhesion 50 mm × 50 mm × in accordance with JIS-A6910
Aqueous resin dispersion was added to a 25 mm mortar test piece and a 150 mm × 70 mm × 3 mm flexible asbestos slate plate in accordance with JIS-A5403 in an amount of 0.1% per square cm.
01g ± 0.005g is applied and dried at 80 ° C for 3 hours. After drying is completed, cool to room temperature and apply 4mm x 4mm
A cross cut of × 25 squares was made, and a coating film peeling test was performed using cellophane tape.

[0058] A: 23 or more squares of the coating remain on the substrate after the peeling test O: 20 to 22 squares of the coating remain on the base after the peeling test Δ: On the base after the peeling test 15 to 19 squares of the coating film remaining ×: 1 square of the coating film remaining on the substrate after the peeling test
Less than 5 squares

(6) Water resistance A coated plate was prepared under the same conditions as in the adhesion test, put in a plastic container, filled with tap water until the coating film surface was completely immersed, and put together with the plastic container in a constant temperature water bath at 40 ° C. for 7 days. put. After 7 days, after confirming the change of the coating film (existence of blisters, peeling, etc.) of the coated plate immediately after taking out, it was dried in a dryer at 50 ° C. for 8 hours, and then subjected to the adhesion test of the above (5). The evaluation was made (the same as the substrate adhesion and the evaluation method).

(7) Film-forming property The aqueous resin dispersion was applied to a glass plate with a wet film thickness of about 100 μm.
And left at 10 ° C. ± 1 ° C. for 24 hours to evaluate the film forming property according to the following criteria.

◎: Complete continuous coating film is formed. ：: A continuous coating film having slight cracks and the like at the periphery is formed. Δ: Fine cracks are observed in the entire coating film, but a continuous coating film is formed. ×: Many cracks and the like were observed, and a continuous coating film was not formed.

(8) Drying property The aqueous resin dispersion liquid was applied to a glass plate with a wet film thickness of about 100 μm.
After the coating was carried out and left under the condition of 20 ° C. ± 1 ° C., the time until the tackiness was not felt when touching with a finger was evaluated according to the following criteria.

[0063] タ: No tackiness is sensed within 30 minutes. ○: Tackiness is not sensed within 1 hour. Δ: Tackiness is not sensed within 1 hour and 30 minutes. ×: No tackiness within 1 hour and 30 minutes. No. Or, the film has not been formed.

Example 1 100 parts of ethyl acetate was charged into a reaction vessel equipped with a stirrer, thermometer, reflux condenser and dropping funnel, and the temperature was raised to 80 ° C. while stirring. Then, while maintaining the internal temperature of the reaction vessel at 80 ° C., 70 parts of methyl methacrylate and 2-ethylhexyl acrylate 14.2 are used.
Part, diacetone acrylamide 0.8 part, methacrylic acid 15 parts, 2,2′-azobis-methylbutyronitrile 8
The resulting mixture was polymerized dropwise over 4 hours.

After completion of the dropping, the internal temperature was maintained at 80 ° C. for 4 hours.
After cooling to room temperature, an ethyl acetate solution of the copolymer (A-1) was obtained. Next, the solvent was removed from the ethyl acetate solution of the copolymer (A-1), and the copolymer (A-
1) was obtained.

A similar reaction vessel was charged with 150 parts of deionized water, and after purging with nitrogen, 90 parts of nitrogen were allowed to flow while flowing nitrogen.
Heat to ° C. 27 parts of methyl methacrylate, 63 parts of 2-ethylhexyl acrylate, and 10 parts of glycidyl methacrylate were added to a reactive emulsifier (Latemul S-1 manufactured by Kao Corporation).
80A) 5 parts of deionized water and 55 parts of deionized water were stirred in a separate container to obtain an emulsion, and 4.5 parts of a 3.3% by mass aqueous solution of sodium persulfate was maintained at 90 ° C. Over a period of 3 hours while dropping separately into the reaction vessel to obtain an aqueous resin dispersion (BD-) of the copolymer (B-1) having a solid content of 32.8% by mass.
1) was obtained.

In a similar reaction vessel, the dispersion (BD-1) 10
0 parts of the copolymer (A-
After 32.8 parts of the pulverized product obtained in 1) was charged and sufficiently stirred, the internal temperature of the reaction vessel was raised to 70 ° C. One hour after the internal temperature reached 70 ° C., a solution prepared by diluting 4 parts of 28% by mass ammonia water with 15 parts of deionized water was added dropwise over 30 minutes, and allowed to stand for 2 hours after completion of the dropwise addition.

After 2 hours, the mixture was cooled to room temperature, and 0.4 part of adipic dihydrazide was added to obtain an aqueous resin dispersion of Example 1. Table 1 shows the composition and Table 2 shows the characteristic values of the aqueous resin dispersion and the results of various performance tests.

Example 2 In a reaction vessel equipped with a stirrer, a thermometer and a reflux condenser, 200 parts of deionized water and 1 part of polyvinyl alcohol (80% saponification, 1700 degree of polymerization) were charged and stirred. While completely dissolving. The stirring was temporarily stopped, and 70 parts of methyl methacrylate, 12 parts of 2-ethylhexyl acrylate, 3 parts of diacetone acrylamide, 15 parts of methacrylic acid, 0.5 part of 2,2′-azobis-methylbutyronitrile, n-dodecyl A mixture obtained by mixing 5 parts of mercaptan is added, and the mixture is sufficiently stirred.
The reaction was performed for 4 hours while maintaining the temperature at 3 ° C. After completion of the reaction, the particulate polymer of the copolymer (A-2) was taken out of the reaction vessel, washed with water, and dried at 40 ° C for 24 hours.

[0070] A similar reaction vessel was charged with 150 parts of deionized water, and after purging with nitrogen, 90 parts of nitrogen were allowed to flow while flowing nitrogen.
The temperature was raised to ° C. 20 parts of methyl methacrylate, 63 parts of 2-ethylhexyl acrylate, and 17 parts of glycidyl methacrylate were mixed with a reactive emulsifier (Latemul S-1 manufactured by Kao Corporation).
80A) 5 parts of deionized water and 55 parts of deionized water were stirred in a separate container to obtain an emulsion, and 4.5 parts of a 3.3% by mass aqueous solution of sodium persulfate was maintained at 90 ° C. Over 3 hours while dropping separately into the reaction vessel to obtain a solid content of 32.8%.
To obtain an aqueous resin dispersion (BD-2) of the copolymer (B-2).

In the same reaction vessel, the dispersion (BD-2) 10
0 parts, and stirring the particulate copolymer (A-
After charging 32.8 parts of 2) and sufficiently stirring, the internal temperature of the reaction vessel was raised to 70 ° C. One hour after the internal temperature reached 70 ° C., a solution prepared by diluting 4 parts of 28% by mass ammonia water with 15 parts of deionized water was added dropwise over 30 minutes, and allowed to stand for 2 hours after completion of the dropwise addition.

After 2 hours, the mixture was cooled to room temperature, and 1.2 parts of adipic dihydrazide was added to obtain an aqueous resin dispersion of Example 2. Table 1 shows the composition and Table 2 shows the characteristic values of the aqueous resin dispersion and the results of various performance tests.

Example 3 The copolymer (A-2) of Example 2 was placed in a reaction vessel equipped with a stirrer, a thermometer, and a reflux condenser.
After adding 00 parts and 200 parts of deionized water and sufficiently stirring, the internal temperature of the reaction vessel was raised to 70 ° C. Internal temperature is 70
1 hour after the temperature reached 90 ° C., 28 mass% ammonia water 1
One part diluted with 50 parts of deionized water was added dropwise over 30 minutes, and allowed to stand for 2 hours after completion of the addition. Then the internal temperature is 90
° C, and 27 parts of methyl methacrylate and 2-ethylhexyl acrylate constituting the copolymer (B-1) were 63 parts.
Parts, glycidyl methacrylate (10 parts), a reactive emulsifier (Kateo Corporation, Latemul S-180A) (5 parts), and deionized water (55 parts) were stirred in another container to obtain an emulsion, 4.5 parts of a 3.3 mass% aqueous solution of sodium was separately dropped into the reaction vessel over 3 hours while maintaining the internal temperature at 90 ° C, and after completion of the dropping, the mixture was left for 2 hours while maintaining the internal temperature at 90 ° C. The copolymer (B) was synthesized in the presence of the copolymer (A).

After 2 hours, the mixture was cooled to room temperature, and 1.6 parts of adipic dihydrazide was added to obtain an aqueous resin dispersion of Example 3. Table 2 shows the composition and Table 3 shows the characteristic values of the aqueous resin dispersion and the results of various performance tests.

Example 4 The procedure of Example 3 was repeated except that the composition of the copolymer (A-3) was changed to 60 parts of methyl methacrylate, 17 parts of butyl acrylate, 3 parts of diacetone acrylamide and 20 parts of methacrylic acid. The aqueous resin dispersion of Example 4 was obtained in the same manner. Table 2 shows the composition and Table 3 shows the characteristic values of the aqueous resin dispersion and the results of various performance tests. However, 1.6 parts of adipic dihydrazide was added.

Example 5 The composition of copolymer (A-4) was changed to 20 parts of methyl methacrylate and 10 parts of t-butyl methacrylate.
Parts, 60 parts of ethyl acrylate, 5 parts of diacetone acrylamide, and 5 parts of methacrylic acid, and a copolymer (B-3) was obtained.
Was changed to 98 parts of 2-ethylhexyl acrylate and 2 parts of glycidyl methacrylate, and the emulsifier used for emulsion polymerization of the copolymer (B-3) was changed (manufactured by Rhodia, A
BEX23-S, using 2 parts) to obtain an aqueous resin dispersion of Example 5 in the same manner as in Example 3. However, adipic dihydrazide was not added.

Table 2 shows the composition and Table 3 shows the characteristic values of the aqueous resin dispersion and the results of various performance tests.

[Comparative Example 1] In a reaction vessel equipped with a stirrer, a thermometer and a reflux condenser, 50 parts of deionized water was charged and purged with nitrogen. Then, the temperature was raised to 90 ° C while flowing nitrogen.

[0079] Methyl methacrylate 32 parts, styrene 25 parts,
38 parts of 2-ethylhexyl acrylate, 3 parts of diacetone acrylamide, and 2 parts of methacrylic acid were stirred in a separate container with 5 parts of a reactive emulsifier (Latemul S-180A manufactured by Kao) and 40 parts of deionized water to emulsify. The liquid product and 4.5 parts of a 3.3% aqueous solution of sodium persulfate were separately dropped into the reaction vessel over 3 hours while maintaining the internal temperature at 90 ° C.
After completion of dropping, the mixture is left for 2 hours while maintaining the internal temperature at 90 ° C.

After 2 hours, the mixture was cooled to room temperature, and 1.9 parts of adipic dihydrazide was added to obtain an aqueous resin dispersion of Comparative Example 1. The characteristic values of the aqueous resin dispersion and the results of various performance tests are as shown in Table 2.

Comparative Example 2 Comparative Example 2 was carried out in the same manner as in Example 2 except that the composition of the copolymer (B-4) was changed to 37 parts of methyl methacrylate and 63 parts of 2-ethylhexyl acrylate.
A water-based resin dispersion was obtained. Table 1 shows the composition and Table 3 shows the characteristic values of the aqueous resin dispersion and the results of various performance tests. However, the amount of adipic dihydrazide added was 1.2 parts.

[Comparative Example 3] The composition of the copolymer (A-6) was changed to 70 parts of methyl methacrylate, 12 parts of 2-ethylhexyl acrylate, 15 parts of diacetone acrylamide and 3 parts of methacrylic acid. In the same manner as in Example 3, an aqueous resin dispersion of Comparative Example 3 was obtained. However, 1.9 parts of adipic dihydrazide were added.

[0083] However, this aqueous resin dispersion liquid was extremely prone to agglomerates, and was not suitable for use as a paint.

Comparative Example 4 The composition of copolymer (A-7) was as follows: methyl methacrylate 40 parts, ethyl acrylate 30 parts, butyl acrylate 12 parts, diacetone acrylamide 3 parts,
An aqueous resin dispersion of Comparative Example 4 was obtained in the same manner as in Example 3, except that methacrylic acid was 15 parts, the composition of the copolymer (B-5) was 90 parts of styrene, and 10 parts of glycidyl methacrylate. Was. Table 2 shows the composition and Table 3 shows the characteristic values of the aqueous resin dispersion and the results of various performance tests. However, 1.6 parts of adipic dihydrazide was added.

[0085]

[Table 1]

(Note) The viscosity of the copolymer (A) indicates the viscosity in an alkaline aqueous solution having a solid content of 25 ± 1% to which 90% by mole of an acid can be neutralized and 28% aqueous ammonia is added.

[0087]

[Table 2]

(Note) The viscosity of the copolymer (A) indicates the viscosity in an alkaline aqueous solution having a solid content of 25 ± 1% to which 28% ammonia water capable of neutralizing 90 mol% of the acid has been added.

(Note) Common to Tables 1 and 2 * 1) Calculated from the charging ratio of the carboxyl group-containing monomer in the copolymer (A) and the glycidyl group-containing monomer in the copolymer (B). * 2) Parts by mass of added adipic acid dihydrazide * 3) Indicates the amount of the added hydrazine group of adipic acid dihydrazide to the carbonyl group contained in the copolymer (A). Calculated from each charge ratio.

[0090]

[Table 3]

[0091]

The coating composition of the present invention can improve the drying property, which is a drawback of water-based paints, because it has a low boiling point alcohol and good dilutability, and has good water resistance and adhesion to various inorganic building materials. Etc. can give a good dry coating film,
It is very useful industrially.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI theme coat ゛ (reference) C09D 7/12 C09D 7/12 Z 133/00 133/00 F term (reference) 4J036 AK11 CD03 DC35 JA01 4J038 CC092 CE052 CG012 CG032 CG172 CH172 DB222 EA011 GA06 GA07 MA08 MA10 MA13 PB05 4J100 AB01P AB07R AF06R AJ02Q AJ08Q AL03P AL04P AL05P AL10Q AM02P AM21R BA13R BA14R CA04 CA05 DA25 FA20 FA21 JA01

Claims (9)

[Claims] 1. A coating film having an aqueous resin dispersion liquid capable of adhering 10 g or more of silica powder per 1 g of resin solid content and dilutable with 50% or more of isopropyl alcohol and having a water absorption of 30% or less. Coating composition. 2. A carbonyl or aldehyde group-containing ethylenically unsaturated monomer unit (), an ethylenically unsaturated carboxylic acid monomer unit (), and a unit and other ethylenically unsaturated monomer units (). A copolymer (A) comprising a glycidyl group-containing ethylenically unsaturated monomer unit () and a non-unit ethylenically unsaturated monomer unit (). The ratio of the number of moles of glycidyl groups in the copolymer (B) to the number of moles of carboxyl groups in the copolymer (A) is in the range of 0.1 to 0.6. The coating composition according to claim 1, wherein 3. The composition of the monomer unit constituting the copolymer (A) is in the range of 0.5 to 10% by mass, 5 to 20% by mass, and 70 to 94.5% by mass. The composition of the monomer units constituting the copolymer (B) is 0.1 units.
The coating composition according to claim 2, wherein the content is in a range of 5 to 20% by mass and a unit of 80 to 99.5% by mass. 4. The coating composition according to claim 2, wherein the copolymer (A) and the copolymer (B) in the aqueous resin dispersion are chemically bonded. The coating composition according to any one of claims 2 to 4, wherein the aqueous resin dispersion further contains a compound having two or more hydrazine residues. The glass transition temperature (Tg) of the copolymer (A) calculated from the Fox equation is higher than the value of the copolymer (B). A coating composition according to any one of the above. 7. The coating composition according to claim 2, wherein the copolymer (A) is obtained by a suspension polymerization method. 8. The coating composition according to claim 2, wherein the copolymer (B) is obtained by an emulsion polymerization method. 9. The copolymer (B) according to claim 2, wherein the copolymer (B) is obtained by an emulsion polymerization method in an alkaline aqueous solution of the copolymer (A). Coating composition.