JPH08283314A - Emulsion resin and water-base topcoating composition containing the same - Google Patents

Abstract

PURPOSE: To obtain a water-base topcoating compsn. used for coating interior and exterior walls of a building and to obtain an emulsion resin used for obtaining the compsn. CONSTITUTION: This emulsion resin is obtd. by the emulsion polymn. of an acrylic monomer and styrene under the condition that 8-14wt.% methanol is added to the reaction system in the emulsion polymn. The water-base topcating compsn. contains 14-23vol.% pigment and an emulsion resin which is obtd. by the emulsion polymn. of an acrylic monomer and styrene under the condition that 8-14wt.% methanol is added to the reaction system in the emulsion polymn.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a water-based top coating composition used for coating interior and exterior walls of buildings and an emulsion resin used therefor.

[0002]

2. Description of the Related Art Conventionally, solvent type acrylic resin paints are predominantly used as the top coat paint for exterior materials among the construction paints of Japan. However, recently, from the viewpoints of pollution prevention, environmental measures, measures against dangerous substances, and health, the water-based top coating is being promoted.

[0003]

However, the drying of conventional water-based paints such as glossy synthetic resin emulsion paint is
It depends on the evaporation of water, so it is cold and humid (winter),
Due to the rainy season (rainy season) or rain within a few hours after painting, problems such as paint flow, loss of luster, and color unevenness occur, causing the water-based coating of exterior coating materials to slow It was

[0004]

SUMMARY OF THE INVENTION An object or technical object of the present invention is to accelerate the drying property of an aqueous paint so that even if the paint is applied in a low temperature and high humidity period or a heavy rainy period, the paint flow, gloss reduction,
An object of the present invention is to provide a water-based top coating composition which is free from color unevenness and has excellent dryness. In order to achieve the above object, the present invention pays particular attention to the drying property of methanol, and as a result of many experiments, it was found that there is a difference in the reproducibility of the drying property depending on the addition amount of methanol, and it is practically applicable. An extremely effective waterborne topcoat composition has been developed. The present invention is an emulsion resin obtained by emulsion-polymerizing an acrylic monomer and styrene, wherein the emulsion resin is prepared by emulsion-polymerizing 8 to 14% by weight of methanol during the emulsion-polymerization reaction. And an emulsion resin obtained by emulsion-polymerizing an acrylic monomer and styrene, containing an emulsion resin obtained by emulsion-polymerizing 8-14% by weight of methanol during the emulsion-polymerization reaction, and having a pigment volume concentration of 14-23%. Which is a water-based top coating composition.

The emulsion resin of the present invention is the same as a general emulsion polymerization in terms of the polymerization method, but for example, a part of ion-exchanged water and a part of methanol are charged into a reaction kettle and stirred at 50. While maintaining the temperature at 50 ° C., the remaining ion-exchanged water and a mixed liquid of methanol, an acrylic monomer, styrene, an emulsifier, and an additive selected from preservatives, fungicides, algae control agents, etc. are heated to 50 ° The solution is dropped while holding it, then heated to 60 ° C. and kept for 8 hours. Then, it is cooled to 35 ° C. to obtain the emulsion resin of the present invention.
However, at this time, the total blending amount of methanol is 8 to 14% by weight.
Must. When the blending amount is less than 8% by weight, the drying property of the aqueous top coating composition intended by the present invention cannot be obtained,
Further, when it exceeds 14% by weight, the coating composition of the present invention is apt to cause surface skinning in the container.

The aqueous top coating composition of the present invention comprises the emulsion resin obtained as described above, a pigment, a pigment dispersant, and
It is obtained by uniformly mixing and dispersing a pH adjusting agent, a defoaming agent, a thickening agent, a film-forming aid, ion-exchanged water and the like. However, the pigment volume concentration at this time must be 14 to 23%. When the pigment volume concentration is less than 14%, the hiding ratio of the water-based top coating composition of the present invention is low, and the finished property is poor even after coating. Also, when the pigment volume concentration exceeds 23%, the gloss value becomes low and a matte coating film is obtained. Pigments that can be used in the present invention include, as white pigments, rutile titanium oxide, and as coloring pigments, if necessary, carbon black, red iron oxide, iron yellow, phthalocyanine blue / green, azo red / yellow, There are red, orange, yellow, etc. of slene type. Surface-treated calcium carbonate may also be used as the extender pigment. Examples of the pigment dispersant that can be used in the present invention include surfactants such as anionic and nonionic surfactants. Examples of the pH adjusting agent that can be used in the present invention include aqueous solutions of potash and potassium. Examples of the defoaming agent that can be used in the present invention include alcohols, glycol derivatives, silicon and the like. Examples of the thickener that can be used in the present invention include water-soluble cellulose derivatives, urethane modified products, sodium alginate and the like. Examples of the film-forming auxiliary that can be used in the present invention include plasticizers, alcohols, ether alcohols and ether esters. The water-based top coating composition of the present invention contains the above-mentioned respective components, and as a coating method, the water-based coating can be applied with a commonly used coating tool such as a brush, roller or airless air spray. Usually, it is applied twice and dried at room temperature. However, the coating film obtained by heating and drying has the same performance.

[0007]

【Example】

Example 1 (1) Production Example of Emulsion Resin Emulsion resins A, B, C, D having the compositions shown in Table 1
E and F were adjusted. The composition parts and percentages are by weight unless otherwise specified.

[0008]

[Table 1]

In emulsion polymerization having the composition shown in Table 1, a part of the raw materials (a) and (f) was charged into a reaction kettle and heated under stirring.
While adding a part of (a) and a part of (f) and maintaining at 50 ° C, while maintaining the remaining mixed solution of (a), (b), (c), (d), (e) and (f) at 50 ° C Drop it. Then raise the temperature to 60 ° C 8
Hold for time. Then cool to 35 ° C., filter off,
Emulsion resins A to F having the characteristics shown in Table 2 were obtained. (B
~ E corresponds to the emulsion resin of the present invention)

[0010]

[Table 2]

(2) Production of Aqueous Topcoat Coating Composition Using the emulsion resins in Table 2, aqueous topcoat coating compositions having the compositions shown in Table 3 were prepared. The composition parts and percentages are by weight unless otherwise specified.

[0012]

[Table 3]

(3) Performance test Using the coating materials shown in Table 3, measurement samples were prepared in the following manner, and the drying time and the state in the container were measured. The results are shown in Table 4 (Nos. 2 to 5 correspond to the aqueous top coating composition of the present invention). In addition, the No. The pigment volume concentrations of paints 1 to 6 were all 22%.

Preparation of dry test pieces: Assuming winter conditions as the test atmosphere conditions, the test is performed at a temperature of 5 ° C. and a humidity of 70% RH. The sample is applied to a glass plate (about 200 × 100 × 2 mm) by JIS K 5400 (film applicator coating) using a B type film applicator having a clearance of 0.150 ± 0.004 mm. Drying performance evaluation method: The coated test piece is left under test atmosphere conditions for a predetermined time and then immersed in water for 15 minutes. Take out from water and observe the test piece and immersion liquid. No abnormality in the coating film; ○ Blistering occurred in the coating film; △ Elution of coating film (cloudiness of immersion liquid); × Evaluation of surface skinning property in container; for emulsion paint 33
The test object up to the 8th minute is placed in a 3 ml round can, left for 7 days in an atmosphere of 50 ° C., opened, and the skin of the paint surface is observed and evaluated. No abnormality; ◯ Dry only the contact part in the can; △ Occurrence of surface coating on the paint; × Others are based on JISK5660 glossy synthetic resin emulsion paint.

[0015]

[Table 4]

As shown in Table 4, emulsion resin A
No. using The coating material of No. 1 does not exhibit water resistance until 2 hours or more have passed since it was evaluated for dryness. This means that the drying conditions worsen in the winter, and therefore coating film flow, blistering, and glossing are likely to occur due to rainfall. . Also, emulsion resin F
No. using The paint of No. 6 has no problem in dryness, but surface skinning easily occurs in the container. Emulsion paint does not re-dissolve once formed into a film. Even in the case of clogging, brush coating, or roller coating, the finished coating film becomes bumpy and gives an unsightly finish. Nos. B, C, D, and E emulsion resins were used. The paints 2 to 5 did not have such a problem and were finished normally. Therefore, within the scope of the present invention, the finishability and the state of the inside of the container are appropriate without problems.

Example 2 An aqueous top coating composition having the composition shown in Table 5 was prepared.

[0018]

[Table 5]

Using the paints in Table 5, samples for measurement were prepared in the same manner as in Example 1 and various physical properties were measured. Table 6 shows the results. (Nos. 8 to 11 correspond to the water-based top coating composition of the present invention) The pigment volume concentration (PVC) is according to Formula 1.

[0020]

[Equation 1]

[0021]

[Table 6]

Table 6 examines the performance by the pigment-resin ratio, that is, the pigment volume concentration (PVC). According to the test results, the performances that significantly show the difference in the pigment volume concentration are the hiding power and the gloss value. Regarding the gloss value, the JIS 5660 gloss and synthetic resin emulsion paint have a 60-degree specular gloss of 70 or more. As for the hiding power, the JIS requires that the hiding ratio be 0.95 or higher. Therefore, No. 8-11 aqueous topcoat compositions of the present invention showed excellent results.

[0023]

EFFECTS OF THE INVENTION According to the present invention, a water-based top coating composition having excellent drying properties can be obtained without causing paint flow, loss of gloss, and color unevenness even when coated at low temperature and high humidity or during heavy rain.

Claims (3)

[Claims] 1. An emulsion resin obtained by emulsion-polymerizing an acrylic monomer and styrene, wherein the emulsion resin is blended with 8 to 14% by weight of methanol during the emulsion-polymerization reaction and emulsion-polymerized. 2. The acrylic monomer is selected from one or more acrylic monomers of normal butyl acrylate, 2 ethylhexyl acrylate, methyl methacrylate, and methyl acrylate.
The emulsion resin described. 3. An emulsion resin obtained by emulsion polymerization of an acrylic monomer and styrene, the emulsion resin containing 8 to 14% by weight of methanol at the time of emulsion polymerization reaction and emulsion-polymerized, and having a pigment volume concentration of 14 ~ 23% aqueous topcoat composition.