JP7440766B2 - Water-based paint composition and coating method - Google Patents

Description

The present invention relates to a water-based coating composition and a coating method.

BACKGROUND OF THE INVENTION In some cases, a wall of a building is covered with a plurality of wall materials such as exterior wall boards, and a coating film is provided on the surface thereof by painting. In such wall surfaces, the spacing between the wall materials changes at the joints between the wall materials due to changes in temperature, etc., and as a result, cracks may occur in the paint film at the joints between the wall materials.

One way to suppress cracks in the paint film at the joints between wall materials is to apply a band-shaped joint treatment material that reduces the force in the spreading direction when the gap between wall materials widens and prevents it from being transmitted to the paint film. A seam treatment method is known in which the seam between the seams and the side edges of the wall materials on both sides of the seam are covered, and a coating film is applied by painting to the surface of the seam treatment material and the surface of the wall materials on both sides of the seam treatment material. There is.

For example, the following materials have been proposed as seam treatment materials.
- An adhesive layer that is pasted to cover the joints between wall materials, a reinforcing layer made of acrylic rubber reinforced with non-woven fabric and provided on the outside of the adhesive layer, and an adhesive layer that is formed between the adhesive layer and the reinforcing layer. In addition, there is a band-shaped seam treatment material having a buffer portion partially provided with a buffer material made of silicone resin (Patent Document 1).

JP2006-233611A

However, the seam treatment method using the seam treatment material described in Patent Document 1 is time-consuming and requires an additional seam treatment material in addition to the paint.

An object of the present invention is to provide a water-based paint composition and a coating method that can form a coating film that is less prone to cracking due to fluctuations in the spacing between wall materials, without having to provide a seam treatment material in advance at the joints between wall materials. purpose.

The present invention has the following aspects.
[1] Contains water and gel particles dispersed in the water,
The gel-like particles have droplets containing an emulsion paint and a gelled film covering the surface of the droplets,
A water-based coating composition in which 20% by mass or more of 100% by mass of the gel particles contains silicone that is liquid at 23°C.
[2] A coating method in which the water-based paint composition of [1] is applied to the surfaces of a plurality of wall materials installed side by side so as to cover at least the joints between the wall materials.

According to the present invention, it is possible to provide a water-based paint composition and a coating method that can form a coating film that is less prone to cracking due to variations in the spacing between wall materials, even without providing a joint treatment material in advance at the joints between wall materials. .

FIG. 2 is a sectional view showing a coating film provided on the surface of an object to be coated and its vicinity by the coating method of the present invention.

[Water-based paint composition]
The water-based coating composition of the present invention includes water and gel particles dispersed in water.
The gel particles have droplets containing emulsion paint and a gelled film covering the surface of the droplets.
20% by mass or more of 100% by mass of gel particles in the water-based coating composition contains silicone that is liquid at 23° C. (hereinafter also referred to as "liquid silicone"). Hereinafter, gel particles containing liquid silicone will also be referred to as "gel particles (1)."
The water-based paint composition may contain only gel particles (1) as gel particles, or may further contain gel particles that do not contain liquid silicone (hereinafter also referred to as "gel particles (2)"). May contain.
The water-based coating composition may further contain a binder resin, if necessary. Note that since the gel particles function as a binder, the water-based coating composition does not need to contain a binder resin.
The water-based coating composition may further contain other components other than those mentioned above, if necessary.

<Water>
The content of water is preferably 30 to 85% by weight, more preferably 40 to 80% by weight based on 100% by weight of the water-based coating composition.

<Gel-like particles (1)>
The gel particles (1) have a droplet and a gelled film covering the surface of the droplet, and contain liquid silicone.

(liquid silicone)
The inclusion of liquid silicone in the gel particles (1) imparts elongation to the coating film of the water-based paint composition, and cracks occur when stress is applied to the coating film due to changes in the spacing between wall materials, etc. can be suppressed. This is thought to be because the liquid silicone imparts slip properties to the surface of the gel particles, and when stress is applied to the coating film, the gel particles shift and the stress is relaxed.
Liquid silicones are typically formulated into droplet emulsion coatings. The low-molecular-weight silicone in the emulsion paint passes through the gel film and migrates to the surface of the gel particles.
Silicone, which is solid at 23° C., cannot migrate to the surface of the gel-like particles.

As the liquid silicone, for example, silicone used as a leveling agent or slip agent for paints can be used.
The liquid silicone is preferably one that is compatible with the resin emulsion of the droplets, and polysiloxane is preferred in terms of slip properties and compatibility.
As the polysiloxane, alkyl polysiloxane is preferable from the viewpoint of slip properties. Examples of the alkylpolysiloxane include dimethylpolysiloxane and polymethylalkylsiloxane. These alkylpolysiloxanes may be modified. Among these, dimethylpolysiloxane is preferred in terms of slip properties. These polysiloxanes may be modified with alkylene oxides such as ethylene oxide and propylene oxide.

The content of liquid silicone in the gel particles (1) is preferably 2 to 10% by weight based on 100% by weight of the gel particles (1). When the content of liquid silicone is at least the lower limit, sufficient elongation can be imparted to the coating film, and when it is at most the upper limit, gel particles (1) can be easily formed.

(droplet)
The droplets contain emulsion paint.
Emulsion paints include resin emulsions.
Emulsion paints typically further include hydrophilic colloid-forming substances.
In the case of gel particles (1), the emulsion paint typically further comprises liquid silicone.
The emulsion paint may further contain components other than those mentioned above (hereinafter also referred to as "optional components").

"Resin emulsion"
A resin emulsion includes suspended particles or emulsified particles made of resin as a forming material, and a dispersion medium in which the suspended particles or emulsified particles are dispersed.
Examples of resins for forming suspended particles or emulsified particles include polyvinyl acetate, acrylic resin, polystyrene, acrylonitrile, Beova (branched fatty acid vinyl ester), natural or synthetic rubber, and emulsions of copolymers thereof. . These resins may be used alone or in combination of two or more. Among these, acrylic resin is preferred.
Water is preferred as the dispersion medium for the resin emulsion.
As the resin emulsion, generally commercially available resin emulsions can be used.

"Hydrophilic colloid-forming substance"
The hydrophilic colloid-forming substance is a substance that can react with a gelling agent to form a gelled film. The gelling agent will be described later.
Examples of the hydrophilic colloid-forming substance include aqueous solutions containing cellulose derivatives, polyethylene oxide, polyvinyl alcohol, natural polymers (casein, starch, galactomannone, guar gum, locust bean gum, etc.), and the like. Among these, an aqueous solution of guar gum is preferred. The concentration of the aqueous solution is preferably 0.5 to 5% by weight, more preferably 1.0 to 3% by weight. One type of hydrophilic colloid-forming substance may be used alone, or two or more types may be used in combination.

The content of the hydrophilic colloid-forming substance is preferably 0.05 to 5 parts by weight, more preferably 0.1 to 3.0 parts by weight, based on 100 parts by weight of the resin emulsion. By controlling the content of the hydrophilic colloid-forming substance within the above range, a stable gelled film can be obtained.

"Liquid silicone"
The liquid silicone is as described above.
The content of liquid silicone in the emulsion paint is set according to the content of liquid silicone in the gel particles (1).

"Optional ingredients"
The emulsion paint may contain pigments such as coloring pigments and extender pigments within a range that does not impair the effects of the present invention. Note that the emulsion paint may be a so-called clear paint that does not contain a pigment.
The emulsion paint may contain known additives such as thickeners, dispersants, antifoaming agents, leveling agents, etc., as long as they do not impair the effects of the present invention.

(gel membrane)
The gelled film covers the surface of the droplet and forms the outline of the gelled particle. Since the surface of the droplet is covered with the gel film, the gel particles can be stably dispersed in the dispersion medium.
Examples of the gelled film include those containing a three-dimensional network formed by the reaction and crosslinking of a hydrophilic colloid substance contained in the emulsion paint with a gelling agent. Gelled films have lower fluidity than emulsion paints and contain droplets inside.

Examples of the gelling agent include magnesium montmorillonite clay, sodium pentachlorophenol, borate, tannic acid, titanium lactate, and calcium chloride. Among these, borates are preferred. One type of gelling agent may be used alone, or two or more types may be used in combination.

The average particle diameter of the gel particles (1) is preferably 5 to 50 mm, more preferably 10 to 40 mm. If the average particle diameter is 5 mm or more, the coating film can easily follow the increasing distance between wall materials without cracking. On the other hand, if the average particle diameter is 50 mm or less, the smoothness of the coating film is good.
The average particle diameter of the gel-like particles is the average value obtained by randomly selecting 20 gel-like particles and measuring their major diameters with a caliper.

<Gel-like particles (2)>
Gel particles (2) are the same as gel particles (1) except that they do not contain liquid silicone, and their preferred embodiments are also the same.

The proportion of gel particles (1) is 20% by mass or more out of 100% by mass of all gel particles (total of gel particles (1) and gel particles (2)) in the water-based paint composition. Yes, it may be 100% by mass. If the proportion of the gel particles (1) is 20% by mass or more, a coating film that can follow the increasing distance between wall materials without cracking can be obtained.

The total content of all gel particles in the water-based coating composition is preferably 30 to 100% by mass, more preferably 40 to 80% by mass, based on 100% by mass of the water-based coating composition. When the total content of gel particles is 30% by mass or more, the workability of coating the object to be coated with the water-based coating composition is good.

<Binder resin>
Examples of the binder resin include polyvinyl acetate, acrylic resin, polystyrene, acrylonitrile, Beova (branched fatty acid vinyl ester), natural or synthetic rubber, and emulsions of copolymers thereof. These resins may be used alone or in combination of two or more. Among these, acrylic resin is preferred.
The binder resin may be blended in the form of a resin emulsion. As the resin emulsion, generally commercially available resin emulsions can be used. Water is preferred as the dispersion medium for the resin emulsion.

When the water-based coating composition contains a binder resin, the content of the binder resin (resin content equivalent in the case of a resin emulsion) is preferably 5 to 40 parts by mass, and 10 to 30 parts by mass, based on 100 parts by mass of gel particles. part is more preferable. When the content of the binder resin is within the above range, it is easy to obtain a coating film that has excellent coating workability and can follow the widening of the spacing between wall materials without cracking.

<Other ingredients>
The water-based paint composition may contain an extender pigment. The extender pigment will be described later.
The water-based coating composition may contain a water-soluble polymer compound. The water-soluble polymer compound will be described later.
The water-based coating composition may contain known additives such as thickeners, dispersants, antifoaming agents, preservatives, leveling agents, etc., to the extent that the effects of the present invention are not impaired.

<Method for producing water-based paint composition>
The aqueous coating composition is prepared, for example, by preparing an aqueous dispersion of gel particles (1), and optionally adding an aqueous dispersion of gel particles (2) to the aqueous dispersion of gel particles (1), It can be manufactured by blending a resin emulsion, optional ingredients, water, etc.

The aqueous dispersion of gel particles (1) can be prepared, for example, by preparing an emulsion paint containing a resin emulsion, a hydrophilic colloid-forming substance, and liquid silicone, and adding the resulting emulsion paint to a gelling agent and water while stirring. It can be prepared by adding it to a dispersion medium containing.

An emulsion paint can be prepared, for example, by adding a hydrophilic colloid-forming substance, liquid silicone, optional components as needed, and water to a resin emulsion, and stirring and mixing the mixture.
Liquid silicones may be used in the form of aqueous dispersions.

The dispersion medium includes a gelling agent and water.
The content (solid content) of the gelling agent is preferably 0.05 to 5% by mass, more preferably 0.1 to 3% by mass, based on 100% by mass of the dispersion medium. By controlling the content of the gelling agent within the above range, a stable gelled film can be obtained.
The content of water is preferably 20 to 80% by mass, more preferably 30 to 70% by mass, based on 100% by mass of the dispersion medium.

The dispersion medium may contain an extender pigment, if necessary.
Extender pigments include kaolin, barium sulfate, hydrated magnesium silicate, calcium carbonate, and the like. Among them, hydrous magnesium silicate is preferred. One type of extender pigment may be used alone, or two or more types may be used in combination.
The content (solid content) of the extender pigment is preferably 0.05 to 10% by mass, more preferably 0.1 to 5% by mass, based on 100% by mass of the dispersion medium.

The dispersion medium may contain a water-soluble polymer compound as necessary.
Examples of water-soluble polymer compounds include hydroxyethyl cellulose, carboxymethyl cellulose, polyvinyl alcohol, and the like. Among them, carboxymethylcellulose is preferred. One type of water-soluble polymer compound may be used alone, or two or more types may be used in combination.
The content (solid content) of the water-soluble polymer compound is preferably 0.05 to 3% by mass, more preferably 0.1 to 2% by mass, based on 100% by mass of the dispersion medium.

The dispersion medium can be prepared, for example, by mixing an aqueous solution of a gelling agent, an aqueous dispersion of an extender pigment, and an aqueous solution of a water-soluble polymer compound, and diluting the mixture with water as necessary.
The concentration of the gelling agent in the gelling agent aqueous solution is preferably 0.05 to 10% by mass, more preferably 0.5 to 8% by mass.
The concentration of the extender pigment in the aqueous dispersion of the extender pigment is preferably 0.05 to 20% by mass, more preferably 2 to 10% by mass.
The concentration of the water-soluble polymer compound in the aqueous solution of the water-soluble polymer compound is preferably 0.1 to 5% by mass, more preferably 0.5 to 3% by mass.

When the emulsion paint is stirred in the dispersion medium, droplets of the emulsion paint are formed, and on the surface of the droplets, the hydrophilic colloid-forming substance of the emulsion paint and the gelling agent of the dispersion medium react to form a three-dimensional network structure. It is formed. Further, the droplets of the emulsion paint are aggregated by reaction with the gelling agent, and are then divided into small pieces by stirring. Even in the process of fragmentation, the hydrophilic colloid-forming substance and the gelling agent continuously react to form a three-dimensional network.
The gel-like particles thus obtained contain a large amount of water and are soft particles.

The amount of the emulsion paint to be blended is preferably 100 to 500 parts by weight, more preferably 150 to 400 parts by weight, per 100 parts by weight of the dispersion medium. By setting the amount of the emulsion paint within the above range, gel particles with a uniform shape can be easily obtained.

The stirring method may be a known method, such as stirring with a disperser such as a dissolver.
The average particle diameter of the resulting gel-like particles can be freely controlled by adjusting the viscosity of the emulsion paint or dispersion medium, the rotation speed of the dispersion machine, the stirring time, and the combination and amount of the hydrophilic colloid-forming substance and gelling agent. Generally, increasing the viscosity of an emulsion paint or dispersion medium increases the average particle size, and increasing the rotation speed of the dispersion machine decreases the average particle size.

Aqueous dispersions of two or more types of gel-like particles (1), each of which emulsion paint contains colored pigments of different tones, may be prepared and then mixed. Thereby, the water-based paint composition can be made into a multi-colored paint composition.

The aqueous dispersion of gel particles (2) can be prepared in the same manner as the aqueous dispersion of gel particles (1), except that the emulsion paint does not contain liquid silicone.
When the emulsion paint of gel particles (1) contains a colored pigment, the emulsion paint of gel particles (2) may contain a colored pigment of a different tone from the emulsion paint of gel particles (1). Thereby, the water-based paint composition can be made into a multi-colored paint composition.

[Painting method]
The coating method of the present invention is a method in which the water-based paint composition of the present invention is applied to the surfaces of a plurality of wall materials installed side by side so as to cover at least the joints between the wall materials.
Hereinafter, one embodiment of the coating method of the present invention will be described with reference to FIG. Note that the dimensional ratio in FIG. 1 is different from the actual one for convenience of explanation.

The object to be painted in the painting method according to the present embodiment includes a plurality of wall materials 10 arranged in parallel. Joints C between adjacent wall materials 10 are filled with joint material 12.
Examples of the wall material 10 include exterior wall materials and interior wall materials of buildings. Examples of the material for the wall material 10 include mortar, concrete, ceramic materials, plastic, metal, and wood. The surface of the wall material 10 may be smooth or may have irregularities. A coating film may be provided on the surface of the wall material 10.
Examples of the joint material 12 include sealing material and putty material.
Note that the joint C may not be filled with the joint material 12.

In the coating method according to the present embodiment, the water-based paint composition of the present invention is applied to the surfaces of a plurality of wall materials 10 arranged in parallel so as to cover at least the seams C between the wall materials 10, and then dried.

The method of applying the water-based coating composition is not particularly limited, and known methods such as roller, spray, brush, and trowel can be used.
The drying temperature is, for example, 5 to 80°C. The drying time varies depending on the drying temperature, but is, for example, 5 minutes to 8 hours.

The coating amount of the water-based coating composition is not particularly limited, but is preferably 150 to 800 g/m ² . If the amount of coating is within the above range, a coating film that can more closely follow the widening of the spacing between wall materials can be formed. The coating amount of the water-based paint composition is the value before drying.

In this way, a continuous coating film 1 is formed that covers the surfaces of the plurality of wall materials 10 and the joints C between the wall materials 10.
The formed coating film 1 has excellent elongation properties. Therefore, it is possible to follow the widening of the interval between the wall materials 10, and cracks are less likely to occur at the joints C.
Other paints may be applied on top of the coating film 1 if necessary.

EXAMPLES The present invention will be explained below with reference to Examples, but the present invention is not limited to these Examples. In the following, "parts" indicate "parts by mass."

<Preparation of emulsion paint>
(Manufacturing example A-1)
31.7 parts of acrylic resin emulsion (manufactured by DIC Corporation, "Boncourt CF-6140", dispersion medium: water, resin content: 48% by mass) and 28.5 parts of a 1.5% by mass aqueous solution of a nonionic guar rubber derivative. (solid content: 0.43 parts), 10 parts of white pigment, and 5 parts of polysiloxane (1) were mixed in a dissolver to prepare a mixed solution (a).
A mixed solution (b) was prepared by mixing 1 part of an anionic polymer dispersant (manufactured by Nippon Acrylic Chemical Co., Ltd., "Orothane 731") and 23.8 parts of water.
Mixed solution (b) was added to mixed solution (a) and stirred to obtain emulsion paint A-1.

(Production examples A-2 to A-10)
Emulsion paint A-2 was prepared in the same manner as in Production Example A-1, except that the types and amounts (parts) of the components to be added to each of mixed liquid (a) and mixed liquid (b) were as shown in Table 1. ~A-10 was manufactured.

The polysiloxanes and pigments used are shown below.
Polysiloxane (1): Liquid silicone (polyether-modified polydimethylsiloxane), "BYK-378" manufactured by BYK Chemie Japan.
Polysiloxane (2): Liquid silicone (aralkyl-modified polymethylalkylsiloxane), "BYK-323" manufactured by BYK Chemie Japan.
White pigment: titanium oxide, manufactured by Ishihara Sangyo Co., Ltd., "Titanium R930".
Black pigment: iron oxide black, manufactured by LANXESS, "Biferox 318".
Tea pigment: Iron-zinc composite oxide, manufactured by Titan Kogyo Co., Ltd., "T-10".
Extender pigment: "SL-1000" manufactured by Takehara Chemical Industry Co., Ltd.

<Production of gel-like particle aqueous dispersion>
(Manufacturing example B-1)
25 parts of a 4% by mass aqueous dispersion of hydrated magnesium silicate (1 part by weight), 5 parts by mass of an aqueous solution of ammonium biborate (0.25 parts by mass) and 1% by mass of sodium carboxymethyl cellulose. After adding 25 parts (solid content 0.25 part) and stirring and mixing, 45 parts of water was added to dilute the mixture to obtain a dispersion medium.

60 parts of emulsion paint A-1 was added to 40 parts of the obtained dispersion medium, and the mixture was stirred with a dissolver until the average particle diameter became 30 mm to obtain gel-like particle aqueous dispersion B-1.
Twenty gel particles were randomly selected from gel particle aqueous dispersion B-1, and the average length of the particles was measured using a caliper and was approximately 30 mm.

(Production examples B-2 to B-9)
Gel particle aqueous dispersions B-2 to B-9 were produced in the same manner as Production Example B-1, except that emulsion coating A-1 was changed to the emulsion coating shown in Table 2.

(Manufacturing example B-10)
When the same operation as in Production Example B-1 was performed except that emulsion paint A-1 was changed to emulsion paint A-10, no gel particles were formed.

<Manufacture and evaluation of water-based coating composition>
(Examples 1 to 13, Comparative Examples 1 to 2)
The gel-like particle aqueous dispersion shown in Tables 3 to 4 and water or acrylic resin emulsion (manufactured by DIC Corporation, "Boncourt CF-6140", dispersion medium: water, resin content 48% by mass) were prepared in Tables 3 to 4. A water-based coating composition was obtained by mixing in the proportions (parts) shown below.
The obtained water-based coating composition was evaluated for elongation and appearance after painting according to the following procedure. The results are shown in Tables 3 and 4.

"Evaluation of extensibility"
A water-based coating composition was applied onto the release paper using a roller at a coating amount (before drying) of 300 g/m ² , and dried at 23° C. for 2 weeks to form a coating film.
Next, the release paper on which the coating film was formed was cut into pieces with a width of 10 mm and a length of 40 mm, and the release paper was peeled off to obtain a measurement piece. The obtained measurement piece was tested for tensile elongation (elongation rate) using a tensile testing machine (manufactured by Orientec Co., Ltd., "Tensilon RTC-1210") under the conditions of a measurement atmosphere of 23°C, rated load of 250 N, and tensile speed of 20 mm/min. ) was measured. The same operation was performed three times and the average value was determined.

"Evaluation of appearance after painting"
Spray it onto the surface of a slate board that has been previously coated with a white colored paint as a base so that the coating amount (before drying) is 300g/ ^m2 , and dry for 2 weeks at 23℃ to form a coating film. did.
The formed coating film was visually observed, and the appearance after coating was evaluated based on the following criteria. Here, the term "bleeding" refers to a state in which the gel particles crumble and the coating film appears cloudy.
A: Good appearance with no bleeding.
B: Slight blurring.

The coating films of the water-based coating compositions of Examples 1 to 13 had excellent elongation properties. Therefore, it can be judged that it can follow the increasing distance between wall materials without cracking.
On the other hand, the coating film of the aqueous coating composition of Comparative Example 1 in which the gel particles did not contain liquid silicone had poor extensibility.
The coating film of the aqueous coating composition of Comparative Example 2 in which the proportion of gel particles containing liquid silicone was 15% by mass out of 100% by mass of gel particles had poor extensibility.

The coating film formed by the water-based coating composition of the present invention has excellent elongation properties. This is thought to be because the liquid silicone that has migrated to the surface of the gel particles allows the gel particles to be displaced to some extent within the coating film. Because the paint film has excellent elongation properties, even if the paint film is formed to cover the joints between wall materials without providing a seam treatment material in advance at the joints between wall materials, the When the distance between wall materials increases, the paint film stretches without cracking, allowing it to accommodate the widening of the distance between wall materials.

1 Paint film C Joint 10 Wall material 12 Joint material

Claims (2)

comprising water and gel-like particles dispersed in the water,
The gel-like particles have droplets containing an emulsion paint and a gelled film covering the surface of the droplets,
A water-based coating composition in which 20% by mass or more of 100% by mass of the gel particles contains silicone that is liquid at 23°C. A coating method comprising applying the water-based paint composition according to claim 1 to the surfaces of a plurality of wall materials installed side by side so as to cover at least the joints between the wall materials.

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