JP5199922B2 - Multi-layer coating formation method - Google Patents

Description

  The present invention relates to a method for forming a multilayer coating film that is unlikely to crack when the top coating film is dried and exhibits good substrate adhesion regardless of the presence or absence of an old coating film.

  In the case of indoor repainting, in order to improve the adhesion between the old coating film already formed on the surface of the substrate and the top coating film, it is necessary to apply a primer coating called a sealer on the old coating film in advance. It is common. Similarly, in the case of a new coating, a sealer is applied on the substrate. When a water-based paint with a high pigment content (for example, matte paint disclosed in Patent Document 1) is used for top coating in a room or the like, the coating film tends to become hard, and the top coating film cannot follow the sealer film swollen by water absorption. There is a problem that cracks are likely to occur during drying. Furthermore, in recent years, there has been a demand for low VOC (volatile organic compounds) in paints for environmental considerations. The Japan Paint Manufacturers Association has set VOC concentrations (ratio to the amount of blending) for indoor building paints to 1% or less. The guidelines are shown. Since such a low VOC paint cannot contain a film-forming aid corresponding to VOC, if a low VOC paint is employed as the top coat, it may cause cracks during drying of the paint film. Therefore, the water-based low-VOC top coating material with a high pigment content has significant cracks that occur when the coating film is dried.

  On the other hand, with regard to the sealer, for environmental considerations, conversion from a solvent-type sealer (for example, Patent Document 2) to an aqueous sealer has been attempted. There is a problem of low adhesion.

  That is, in the method of forming a multi-layer coating film that forms a top coating film on an aqueous sealer coating film, when a low VOC coating material with a high pigment content is used as the top coating composition, Both the adhesion to the film and the crack resistance of the top coating film are insufficient, and it is very difficult to obtain a good multilayer coating film.

JP 2003-147275 A Japanese Patent Laid-Open No. 11-286646

  The present invention has been made in order to solve the above-described conventional problems. The object of the present invention is to prevent cracking when the top coat film is dried and to have good adhesion to the base material or the old paint film. It is in providing the formation method of the multilayer coating film shown.

The multilayer coating film forming method of the present invention is a multilayer coating film forming method in which a coating film is formed in the order of a sealer coating film and a top coating film on a base material or an old coating film, and the sealer coating film is formed. The sealer composition has a glass transition temperature of the core part of 20 to 60 ° C., a glass transition temperature of the shell part of 20 to 40 ° C., and a glass transition temperature of the core part of not less than the glass transition temperature of the shell part. And a top coating composition comprising a core-shell type acrylic emulsion having a solid mass ratio of the core part / shell part of 50/50 to 80/20 and forming the top coating film is VOC (volatile organic The content of the compound) is a low VOC paint having a content of 1% by mass or less with respect to the total amount of the top coating composition, and is 70 to 90% by mass with respect to the total solid content in the top coating composition. Containing pigments.
In a preferred embodiment, the acrylic emulsion is cationic.
In a preferred embodiment, the sealer composition does not contain a color pigment.

  According to the present invention, by forming a top coat film on a sealer film formed by a sealer composition containing a specific core-shell type acrylic emulsion, cracking is unlikely to occur when the top coat film is dried. A multilayer coating film having good adhesion to the material or the old coating film can be formed. More specifically, the core-shell type acrylic emulsion has a core part and a shell part having a specific glass transition temperature, and has a core part / shell part at a specific solid content mass ratio. Since the sealer coating formed by the sealer composition containing such a core-shell type acrylic emulsion is excellent in adhesion to the base material or the old coating (hereinafter also simply referred to as adhesion) and exhibits an appropriate coating hardness, According to the present invention, an excellent multilayer coating film can be formed as described above. Such an effect is formed by a top coating composition in which the top coating film contains a large amount of pigment and has a low VOC content (that is, it contains no or only a small amount of a film-forming aid). Even if it is done, it is demonstrated effectively.

A. Sealer coating formation
A-1. Sealer Composition In the method for forming a multilayer coating film of the present invention, first, a sealer coating film is formed on a substrate. The sealer coating film is formed by a sealer composition containing a core-shell type acrylic emulsion.

  The sealer composition may be a transparent sealer composition that does not contain a color pigment, or a color sealer composition that contains a color pigment. A transparent sealer is preferable. This is because a transparent sealer does not contain a color pigment, so the content ratio of the core-shell type acrylic emulsion is increased, and a sealer coating film having high adhesion can be obtained.

  When the sealer composition is a colored sealer composition, the content ratio of the color pigment is preferably 10 to 40% by mass, more preferably 20 to 30% by mass, based on the total amount of solids in the composition. %. When the content ratio of the color pigment is more than 40% by mass, the content ratio of the core-shell type acrylic emulsion is decreased, and the adhesion may be lowered. When the content is less than 10% by mass, the hiding power required for the color sealer coating film May not develop. Examples of the color pigment include titanium oxide, yellow iron oxide, red iron oxide, carbon black, phthalocyanine blue, phthalocyanine green, azo red, quinacridone red, and benzimidazolone yellow.

  The solid content of the core-shell type acrylic emulsion in the sealer composition is preferably 95 to 100% by mass with respect to the total solid content in the sealer composition when the sealer composition does not contain a color pigment. Yes, more preferably 98 to 100% by mass, and when the sealer composition contains a color pigment, it is preferably 55 to 80% by mass, more preferably 65%, based on the total amount of solids in the sealer composition. -80 mass%.

  The sealer composition may further contain additives as necessary. Examples of the additive include a dispersant, a viscosity modifier, an antifoaming agent, a curing catalyst, a surface modifier, a plasticizer, an antioxidant, and an antiseptic. The kind and amount of the additive to be contained can be appropriately selected depending on the purpose.

  The core-shell type acrylic emulsion has a core part as a central part and a shell part as an outer shell part, and the core part and the shell part are obtained from monomer mixtures having different compositions. Preferably, the core part and the shell part have different glass transition temperatures. In general, the glass transition temperature affects the hardness of the resulting coating film. If the glass transition temperature is lowered, a coating film with low hardness is obtained, and the coating film exhibits high adhesion. On the other hand, when such a low-hardness coating film is used as the sealer coating film, the degree of deformation of the sealer coating film is large, and the top coating film formed on the sealer coating film can follow the deformation of the sealer coating film. It may disappear and cracking may occur easily. Moreover, if the glass transition temperature is increased, a coating film having high hardness can be obtained. When the coating film with high hardness is used as a sealer coating film, the crack resistance of the top coating film can be improved, but sufficient adhesion may not be obtained. In the present invention, by using a core-shell type acrylic emulsion having a core portion and a shell portion having different glass transition temperatures, a sealer coating film excellent in both adhesion and crack resistance of the top coating film can be obtained. The glass transition temperature can be measured with a differential scanning calorimeter (DSC) or the like.

  The glass transition temperature of the said core part is 20-60 degreeC, Preferably it is 40-60 degreeC. If the glass transition temperature of a core part is such temperature, the sealer coating film of suitable coating-film hardness can be obtained. If the glass transition temperature of the core portion is lower than 20 ° C, the coating hardness of the resulting sealer coating is too low, so that the crack resistance of the top coating may be reduced. Since the coating film hardness becomes too high, the film-forming property and adhesion of the sealer coating film may be lowered.

  The glass transition temperature of the shell part is 20 to 40 ° C. If the glass transition temperature of a shell part is such a temperature, the sealer coating film which is excellent in adhesiveness can be obtained. If the glass transition temperature of the shell part is lower than 20 ° C., the coating film hardness of the resulting sealer coating film is too low, so that the crack resistance of the top coating film may be lowered. Therefore, there is a possibility that the adhesion may be lowered and the film-forming property of the sealer coating film at room temperature may be lowered.

  In the core-shell type acrylic emulsion, the glass transition temperature of the core part is equal to or higher than the glass transition temperature of the shell part, and the temperature difference is preferably 10 ° C. or higher. With such a core-shell type acrylic emulsion, a sealer coating film excellent in both adhesion and coating film hardness can be obtained. Furthermore, if the core-shell type acrylic emulsion having a glass transition temperature of 10 ° C. higher than the glass transition temperature of the shell part is used, the contribution of the core part having a high glass transition temperature mainly improves the crack resistance of the top coat film. It is possible to obtain a more excellent sealer coating without impairing the adhesion of the sealer coating mainly composed of the shell part having a low glass transition temperature.

  The said core part and shell part can be made into a desired glass transition temperature by the composition of the monomer mixture used for superposition | polymerization of a core part and a shell part, respectively. Any of the monomer mixtures used for the polymerization of the core part and the shell part contains an ethylenically unsaturated monomer. Preferably, the core part and the shell part are polymerized using monomer mixtures having different types and / or blending ratios of ethylenically unsaturated monomers. As a result, the glass transition temperature is different (the glass transition temperature of the core portion is higher than that of the shell portion), and a core portion and a shell portion having desired glass transition temperatures can be obtained. Examples of the ethylenically unsaturated monomer include acrylic acid, methacrylic acid, methyl (meth) acrylate, ethyl (meth) acrylate, n-butyl (meth) acrylate, isobutyl (meth) acrylate, and t-butyl (meth) acrylate. (Meth) acrylic acid alkyl esters such as 2-ethylhexyl (meth) acrylate, lauryl (meth) acrylate, cyclohexyl (meth) acrylate, and dimethylaminoethyl (meth) acrylate; vinyl compounds of styrene and methylstyrene; (meth) acrylonitrile And the like. The said ethylenically unsaturated monomer can also be used individually or in combination of 2 or more types. In one embodiment, a monomer mixture containing methyl methacrylate is used for each of the core part and the shell part, and a desired glass transition temperature is obtained for each of the core part and the shell part by changing the content ratio of methyl methacrylate in the monomer mixture. Can be obtained. More specifically, the glass transition temperature can be increased by increasing the content ratio of methyl methacrylate in the monomer mixture.

  In the core-shell type acrylic emulsion, the mass ratio of the solid content of the core part / shell part is 50/50 to 80/20, preferably 60/40 to 80/20, more preferably 60/40 to 75/25. It is. When the solid content mass ratio of the core part is larger than 80 and the solid content mass ratio of the shell part is smaller than 20, the contribution of the shell part is reduced, and the adhesion of the sealer coating film may be lowered. Further, when the solid mass ratio of the core part is smaller than 50 and the solid mass ratio of the shell part is larger than 50, the contribution of the core part is reduced, the hardness of the sealer coating is lowered, and the crack resistance of the top coating film is reduced. May decrease.

  The solid content concentration of the core-shell type acrylic emulsion is preferably 10 to 40% by mass, more preferably 15 to 35% by mass.

  The core-shell type acrylic emulsion may be anionic or cationic. Of these, a cationic core-shell acrylic emulsion is preferable. If it is a cationic core-shell type acrylic emulsion, a highly adherent sealer coating can be obtained.

  The anionic core-shell acrylic emulsion has a shell portion (anionic shell portion) obtained by polymerizing a monomer mixture containing an anionic monomer. Examples of the anionic monomer include acrylic acid, methacrylic acid, acrylic acid dimer, crotonic acid, 2-acryloyloxyethylphthalic acid, 2-acryloyloxyethyl succinic acid, 2-acryloyloxyethyl acid phosphate, 2 Acrylamide-2-methylpropanesulfonic acid, ω-carboxy-polycaprolactone mono (meth) acrylate, isocrotonic acid, α-hydro-ω-[(1-oxo-2-propenyl) oxy] poly [oxy (1-oxo -1,6-hexanediyl)], maleic acid, fumaric acid, itaconic acid, 3-vinylsalicylic acid, 3-vinylacetylsalicylic acid and the like. Acrylic acid is preferable. The solid content acid value of the anionic shell part is preferably 50 to 90 mgKOH / g, more preferably 60 to 80 mgKOH / g.

  The cationic core-shell acrylic emulsion has a shell portion (cationic shell portion) obtained by polymerizing a monomer mixture containing a cationic monomer. Examples of the cationic monomer include dimethylaminomethyl (meth) acrylate, diethylaminomethyl (meth) acrylate, dibutylaminomethyl (meth) acrylate, dihexylaminomethyl (meth) acrylate, dimethylaminoethyl (meth) acrylate, diiso Examples include amino group-containing monomers such as hexylaminoethyl acrylate, dihexylaminopropyl (meth) acrylate, and di (t-butyl) aminohexyl (meth) acrylate. Preferred is dimethylaminoethyl methacrylate. The solid content amine value of the cationic shell part is preferably 30 to 150 mgKOH / g, more preferably 50 to 100 mgKOH / g.

  As a method for producing the core-shell type acrylic emulsion, for example, in the presence of a shell portion that has been polymerized in advance, a method of polymerizing a monomer mixture for forming a core portion containing the above ethylenically unsaturated monomer using water as a solvent. Can be mentioned. As the charging ratio of the monomer mixture for forming the shell part and the core part, an appropriate charging ratio can be adopted depending on the desired solid mass ratio of the core part / shell part.

  In the polymerization method as described above, a monomer mixture for forming a core part, the remaining shell part and water-containing pre-emulsified liquid are dropped into a mixed liquid in which a part of the shell part to be used is previously charged in water. It is also possible to adopt a method to do. In this way, when the shell part is charged first, the amount of the shell part charged first is preferably 5 to 15% by mass, more preferably based on the total amount of the core part forming monomer mixture and the solid content of the shell part. Is 8-12% by mass.

  Any appropriate polymerization initiator can be adopted as the polymerization initiator used in the polymerization of the core-shell acrylic emulsion. Examples of the polymerization initiator for obtaining an anionic core-shell acrylic emulsion include persulfates such as ammonium persulfate and potassium persulfate; peroxides such as t-butyl hydroperoxide and hydrogen peroxide. Examples of the polymerization initiator for obtaining a cationic core-shell type acrylic emulsion include water-soluble azo compounds such as 2,2 'azobiz (2- (2-imidazolin-2-yl) propane).

  An emulsifier may be used in the polymerization of the core-shell type acrylic emulsion. Any appropriate emulsifier can be adopted as the emulsifier. Examples of the emulsifier include fatty acid salts such as sodium lauryl sulfate, higher alcohol sulfate esters, alkylbenzene sulfonates such as sodium dodecylbenzene sulfonate, polyoxyethylene alkyl ether sulfates, and polyoxynonyl phenyl ether sulfonate ammonium. Anionic surfactants such as reactive emulsifiers such as alkyl allyl polyether sulfate, polyoxyethylene polyoxypropylene glycol ether sulfate, monomers having sulfonic acid groups or sulfate ester groups; polyoxyethylene alkyl ether, poly Polyoxyethylene alkylphenyls such as oxynonylphenyl ether, sorbitan fatty acid esters, polyoxyethylene fatty acid esters, polyoxyethylene-polyoxypropylene esters Alkylamine salts, cationic surfactants such as quaternary ammonium salts; Kkukoporima, nonionic surfactants such as reactive nonionic surfactant (modified) polyvinyl alcohol and the like. The above emulsifiers can be used alone or in combination of two or more.

  The content of the emulsifier is preferably 0.01 to 10% by mass with respect to the total amount of monomers used in the polymerization of the core-shell type acrylic emulsion. Furthermore, chain transfer agents such as t-dodecyl mercaptan, n-octyl mercaptan, n-dodecyl mercaptan, mercaptoacetic acid, mercaptopropionic acid, and 2-mercaptoethanol can be used as necessary.

  The polymerization temperature in the polymerization of the core-shell type acrylic emulsion is preferably 40 to 110 ° C, more preferably 65 to 90 ° C. The polymerization time is preferably 1 to 12 hours, more preferably 2 to 6 hours.

  The shell part can be obtained by polymerizing a monomer mixture for forming a shell part containing the above-mentioned ethylenically unsaturated monomer.

  Any appropriate solvent can be adopted as a solvent used when the shell portion is polymerized. Examples of the solvent include glycols such as ethylene glycol and diethylene glycol, glycol ethers such as dipropylene glycol methyl ether and propylene glycol methyl ether, diglycols such as methyl carbitol, ethyl carbitol, and butyl carbitol, and isopropanol. , Alcohols such as methanol, ethanol, 2-ethylhexanol and cyclohexanol.

  Any appropriate polymerization initiator can be adopted as the polymerization initiator used when the shell portion is polymerized. Examples of the polymerization initiator include organic peroxides such as benzoyl peroxide, t-butyl peroxide and cumene hydroperoxide, azobiscyanovaleric acid and azobisisobutyronitrile.

  The polymerization temperature in the polymerization of the shell part is preferably 80 to 160 ° C, more preferably 100 to 140 ° C. The polymerization time is preferably 1 to 12 hours, more preferably 2 to 8 hours.

A-2. The substrate in which the sealer composition in a multilayer coating film forming method of the coating process the present invention sealer composition is coated may employ any suitable substrate. Examples of the base material include metal base materials such as iron, stainless steel, aluminum and surface treated products thereof, cement-based base materials such as cements, limes, and plasters, polyvinyl chlorides, polyesters, polycarbonates, Examples thereof include plastic base materials such as acrylics. Moreover, the old coating film may be formed in the said base material. That is, the multilayer coating film forming method of the present invention can be usefully used for repainting building materials and the like. In addition, in this specification, an old coating film means the coating film formed with the various coating materials apply | coated to the surface of building materials etc., for example, stain | pollution | contamination adheres with time, or ultraviolet rays, moisture, etc. It is a coating film deteriorated by the influence.

  Examples of the method for applying the sealer composition to the substrate include brush coating, air spray, airless spray, and roller coating.

The coating amount of the sealer composition of the present invention can be set to any appropriate coating amount depending on the application. Generally, it is preferable that it is 10-300 g / m < ² >.

  Any appropriate drying method may be employed as a method for drying the sealer composition of the present invention. Natural drying or heat drying is preferred. In the case of natural drying, the drying time is preferably 3 hours or longer, more preferably 24 hours or longer.

B. Formation of top coat
B-1. Top coating composition The method for forming a multilayer coating film of the present invention includes coating the top coating composition on the sealer coating film formed as described above to form a top coating film.

  The above-mentioned top coating composition contains any appropriate resin as a binder component. Examples of the resin include an acrylic resin, a polyester resin, an alkyd resin, and an epoxy resin.

  The top coat composition preferably comprises any suitable pigment. Examples of the pigment include coloring pigments such as titanium oxide, yellow iron oxide, red iron oxide, carbon black, phthalocyanine blue, phthalocyanine green, azo red, quinacridone red, benzimidazolone yellow; calcium carbonate, barium sulfate, kaolin, clay And extender pigments such as talc.

  The content of the pigment is 70 to 90% by mass, preferably 80 to 90% by mass, based on the total amount of solids in the top coating composition. According to the method for forming a multi-layer coating film of the present invention, by forming a top coating film on the sealer coating film, a top coating composition having a high pigment content (such as a matte coating system). Even when a top coat film obtained by a paint system having a low resin component), that is, a top coat film with high film hardness and high internal stress is formed, the crack resistance of the top coat film and the basis of the sealer film A multilayer coating film having excellent adhesion to the material or the old coating film can be obtained. In other words, one of the excellent effects of the present invention is that a top coating composition having a high pigment content can be employed even in applications where the crack resistance and adhesion of the coating film are highly required. .

  The top coating composition is a low VOC coating composition. Content of VOC is 1 mass% or less with respect to the whole quantity of the said top-coat coating composition, Preferably the said top-coat paint composition does not contain VOC. Here, VOC means a volatile organic compound. Thus, if it is a top-coat paint composition with little VOC content, an environmental load can be reduced more. Further, according to the method for forming a multilayer coating film of the present invention, by forming a top coating film on the sealer coating film, even in such a top coating composition having a low VOC content, crack resistance A top coat film having excellent properties can be obtained.

  The top coating composition may further contain any appropriate additive. Examples of the additive include a curing catalyst, a pigment dispersant, a thickener, a surface conditioner, an ultraviolet absorber, an antioxidant, a silane coupling agent, a flame retardant, an antistatic agent, and a rust inhibitor. .

  The top coating composition can be obtained by mixing and stirring the above components using any appropriate method such as a ball mill or a disper.

B-2. Coating method of top coating composition As a method of coating the top coating composition, for example, depending on coating equipment such as brush, air spray, airless spray, roller, and coating equipment such as curtain flow, roll, dip, etc. Is a method of coating 1-2 times.

  Arbitrary appropriate viscosity can be employ | adopted for the viscosity at the time of the coating of the said top coat composition according to the said coating method.

The coating amount per one time of the top coating composition is preferably 0.05 to 0.5 kg / m ² , more preferably 0.08 to 0.3 kg / m ² .

  Any appropriate drying method may be adopted as a method for drying the top coating composition. Natural drying is preferred. In the case of natural drying, the drying time is preferably 24 hours or longer.

  EXAMPLES Hereinafter, although an Example demonstrates this invention in detail, this invention is not limited to these Examples. Unless otherwise specified, parts and% in the examples are based on mass.

[Evaluation]
<Evaluation of adhesion on extruded cement board>
Each of the sealer compositions obtained in the examples and comparative examples was applied on an extruded cement board at a coating amount of 100 g / m ² using a brush. After coating, after drying at room temperature for 3 hours, a strip-like cloth tape (product name “Nichiban cloth tape No. 106GR” manufactured by Nichiban Co., Ltd.) having a width of 1 cm and a length of 15 cm is applied to the surface of the coating film. DAN fresh R (manufactured by Nippon Paint Co., Ltd., single-layer elastic acrylic emulsion resin paint) was applied at a coating amount of 300 g / m 2 over the part where the adhesive was attached. After drying this at room temperature for 7 days, the state on the substrate when the fabric tape was peeled off was visually evaluated according to the following criteria.
(Double-circle): The film | membrane formed by sealer application | coating remains completely, and the DAN fresh R coating film of cloth tape periphery remains.
○: Most of the film formed by the sealer coating remains, and the DAN fresh R coating around the fabric tape remains.
Δ: About half of the film formed by applying the sealer remains, and part of the DAN fresh R coating around the fabric tape is peeled off.
X: The film | membrane formed by sealer application hardly remains, and the DAN fresh R coating film of cloth tape periphery has peeled.

<Evaluation of crack resistance of top coating film>
Each of the sealer compositions obtained in Examples and Comparative Examples was applied to a 10 × 20 cm slate plate at a coating amount of 100 g / m ² using a brush. After coating, it was dried at room temperature for 3 hours to obtain a sealer coating film. A coating solution obtained by diluting the top coating composition a obtained in Production Example 37 to be described later with 7% water was applied onto the obtained sealer coating film at a coating amount of 120 g / m ² using a brush. After coating, the appearance of the multilayer coating film obtained by drying at room temperature for 1 day was visually confirmed and evaluated according to the following criteria.
Moreover, also about the multilayer coating film obtained by the reference example, the external appearance was confirmed visually and the following reference | standard evaluated.
A: There is no crack at all.
○: 1 to 2 places and a few cracks of several mm are generated on the coated surface.
Δ: There are three or more cracks on the coated surface and a slight crack of several mm.
×: Tortoise-like cracks occur on the entire coating surface.

[Production Example 1] Production of resin for forming anionic shell part (shell resin A) 23.9 parts of dipropylene glycol methyl ether and 16.1 parts of propylene glycol methyl ether are added to a reaction vessel and mixed and stirred in a nitrogen stream. The temperature was raised to 120 ° C. Next, a monomer mixed solution consisting of 43.0 parts of methyl methacrylate, 8.0 parts of styrene, 39.0 parts of n-butyl acrylate and 10.0 parts of acrylic acid, 10.0 parts of dipropylene glycol methyl ether and t -An initiator solution consisting of 2.0 parts of butylperoxy-2-ethylhexanoate was dropped into the reaction vessel in parallel over 3 hours. After completion of the dropping, aging was performed at 120 ° C. for 0.5 hours.
Further, an initiator solution consisting of 5.0 parts of dipropylene glycol methyl ether and 0.3 part of t-butylperoxy-2-ethylhexanoate was dropped into the reaction vessel over 0.5 hours. After completion of dropping, aging was performed at 120 ° C. for 1 hour. Subsequently, 16.1 parts of the solvent was distilled off at 110 ° C. under reduced pressure (70 Torr) using a solvent removal apparatus, and then 187.2 parts of deionized water and 12.4 parts of dimethylaminoethanol were added, and the nonvolatile content was 30% by mass. An anionic shell portion forming resin (shell resin A) having a number average molecular weight of 27,000, a solid content acid value of 76.2 mgKOH / g, and a glass transition temperature (Tg) of 20 ° C. was obtained.

[Production Example 2] Production of resin for forming anionic shell part (shell resin B) 54.0 parts of methyl methacrylate instead of 43.0 parts of methyl methacrylate, acrylic instead of 39.0 parts of n-butyl acrylate Except for using 28.0 parts of acid n-butyl, in the same manner as in Production Example 1, the non-volatile content was 30% by mass, the number average molecular weight was 27,000, the solid content acid value was 76.2 mgKOH / g, the glass transition temperature (Tg ) An anionic shell part forming resin (shell resin B) at 40 ° C. was obtained.

[Production Example 3] Production of cationic shell part forming resin (shell resin C) 23.9 parts of dipropylene glycol methyl ether and 16.1 parts of propylene glycol methyl ether were added to a reaction vessel, and mixed and stirred in a nitrogen stream. The temperature was raised to 120 ° C. Next, a monomer mixed solution consisting of 27.0 parts of methyl methacrylate, 8.0 parts of styrene, 45.0 parts of n-butyl acrylate and 20.0 parts of dimethylaminoethyl methacrylate, 10.0 dipropylene glycol methyl ether And an initiator solution consisting of 2.0 parts of t-butylperoxy-2-ethylhexanoate were added dropwise to the reaction vessel in parallel over 3 hours. After completion of the dropping, aging was performed at 120 ° C. for 0.5 hours.
Further, an initiator solution consisting of 5.0 parts of dipropylene glycol methyl ether and 0.3 part of t-butylperoxy-2-ethylhexanoate was dropped into the reaction vessel over 0.5 hours. After completion of dropping, aging was performed at 120 ° C. for 1 hour. Next, after removing 16.1 parts of the solvent at 110 ° C. under reduced pressure (70 Torr) using a solvent removal apparatus, 191.9 parts of deionized water and 7.6 parts of glacial acetic acid were added, and the nonvolatile content was 30% by mass. A cationic shell part forming resin (shell resin C) having a number average molecular weight of 27,000, a solid content amine value of 69.9 mgKOH / g, and a glass transition temperature (Tg) of 0 ° C. was obtained.

[Production Example 4] Production of cationic shell part forming resin (shell resin D) 40.0 parts of methyl methacrylate instead of 27.0 parts of methyl methacrylate, acrylic instead of 45.0 parts of n-butyl acrylate Except that 32.0 parts of n-butyl acid was used, the same procedure as in Production Example 3 was carried out, the nonvolatile content was 30% by mass, the number average molecular weight was 27,000, the solid content amine value was 69.9 mgKOH / g, the glass transition temperature (Tg ) A cationic shell part forming resin (shell resin D) at 20 ° C. was obtained.

[Production Example 5] Production of cationic shell portion forming resin (shell resin E) 52.0 parts of methyl methacrylate instead of 27.0 parts of methyl methacrylate, acrylic instead of 45.0 parts of n-butyl acrylate Except for using 20.0 parts of acid n-butyl, the same procedure as in Production Example 3 was repeated, except that the nonvolatile content was 30% by mass, the number average molecular weight was 27,000, the solid content amine value was 69.9 mgKOH / g, and the glass transition temperature (Tg ) A cationic shell part forming resin (shell resin E) at 40 ° C. was obtained.

[Production Example 6] Production of cationic shell part forming resin (shell resin F) Instead of 27.0 parts of methyl methacrylate, 62.0 parts of methyl methacrylate and acrylic instead of 45.0 parts of n-butyl acrylate Except for using 10.0 parts of n-butyl acid, the same procedure as in Production Example 3 was repeated, and the nonvolatile content was 30% by mass, the number average molecular weight was 27,000, the solid content was 69.9 mgKOH / g, the glass transition temperature (Tg ) A cationic shell portion forming resin (shell resin F) at 60 ° C. was obtained.

[Production Example 7] Preparation of monomer mixture (I) for forming core part 30.0 parts of methyl methacrylate, 30.0 parts of styrene, 39.0 parts of n-butyl acrylate, and 1.0 part of acrylic acid were mixed. A core mixture-forming monomer mixture (I) having a glass transition temperature (Tg) of 20 ° C. was prepared.

[Production Example 8] Preparation of monomer mixture (II) for forming core part 41.0 parts of methyl methacrylate instead of 30.0 parts of methyl methacrylate, n-acrylic acid instead of 39.0 parts of n-butyl acrylate A core mixture-forming monomer mixture (II) having a glass transition temperature (Tg) of 40 ° C. was prepared in the same manner as in Production Example 7, except that 28.0 parts of butyl was used.

[Production Example 9] Preparation of monomer mixture (III) for forming a core part In place of 30.0 parts of methyl methacrylate, 46.0 parts of methyl methacrylate and n-butyl acrylate in place of 39.0 parts of acrylic acid n- A core mixture-forming monomer mixture (III) having a glass transition temperature (Tg) of 50 ° C. was prepared in the same manner as in Production Example 7, except that 23.0 parts of butyl was used.

[Production Example 10] Preparation of monomer mixture (IV) for forming core part 51.0 parts of methyl methacrylate instead of 30.0 parts of methyl methacrylate, n-acrylic acid instead of 39.0 parts of n-butyl acrylate A core mixture-forming monomer mixture (IV) having a glass transition temperature (Tg) of 60 ° C. was prepared in the same manner as in Production Example 7 except that 18.0 parts of butyl was used.

[Production Example 11] Preparation of monomer mixture (V) for forming a core part In place of 30.0 parts of methyl methacrylate, 24.0 parts of methyl methacrylate and n-butyl acrylate in place of 39.0 parts of acrylic acid n- A core mixture-forming monomer mixture (V) having a glass transition temperature (Tg) of 10 ° C. was prepared in the same manner as in Production Example 7 except that 40.0 parts of butyl was used and acrylic acid was not used.

[Production Example 12] Preparation of core part forming monomer mixture (VI) Manufacture except that 40.0 parts of n-butyl acrylate was used in place of 39.0 parts of n-butyl acrylate and no acrylic acid was used. In the same manner as in Example 7, a monomer mixture (VI) for forming a core part having a glass transition temperature (Tg) of 20 ° C. was prepared.

[Production Example 13] Preparation of monomer mixture (VII) for forming core part 42.0 parts of methyl methacrylate instead of 30.0 parts of methyl methacrylate, n-acrylic acid instead of 39.0 parts of n-butyl acrylate A core mixture-forming monomer mixture (VII) having a glass transition temperature (Tg) of 40 ° C. was prepared in the same manner as in Production Example 7 except that 28.0 parts of butyl was used and acrylic acid was not used.

[Production Example 14] Preparation of monomer mixture (VIII) for forming a core part In place of 30.0 parts of methyl methacrylate, 47.0 parts of methyl methacrylate and n-butyl acrylate in place of 39.0 parts of acrylic acid n- A core mixture-forming monomer mixture (VIII) having a glass transition temperature (Tg) of 50 ° C. was prepared in the same manner as in Production Example 7, except that 23.0 parts of butyl was used and acrylic acid was not used.

[Production Example 15] Preparation of monomer mixture (IX) for forming core part 52.0 parts of methyl methacrylate instead of 30.0 parts of methyl methacrylate, n-acrylic acid instead of 39.0 parts of n-butyl acrylate A core mixture-forming monomer mixture (IX) having a glass transition temperature (Tg) of 60 ° C. was prepared in the same manner as in Production Example 7 except that 18.0 parts of butyl was used and acrylic acid was not used.

[Production Example 16] Production of anionic core-shell acrylic emulsion (1) In a reaction vessel equipped with a stirrer, a thermometer, a dropping funnel, a reflux condenser, a nitrogen inlet, etc., 100 parts of deionized water and Production Example 2 33.3 parts of the obtained shell resin B was charged and heated to 80 ° C. with stirring.
40.0 parts of monomer mixture (I) obtained in Production Example 7 was mixed with 30.0 parts of deionized water and an emulsion mixture consisting of 166.7 parts of shell resin B obtained in Production Example 2, and a homogenizer To prepare a pre-emulsion solution. Subsequently, the prepared pre-emulsion was dropped into the reaction vessel with stirring for 3 hours.
In parallel with dropping of the pre-emulsion, an aqueous solution obtained by dissolving 0.3 part of ammonium persulfate as a polymerization initiator in 30 parts of water was maintained until the completion of dropping of the pre-emulsion while keeping the dropping rate constant. It was dripped in. After completion of dropping of the pre-emulsion, the reaction is further continued at 80 ° C. for 1 hour, followed by cooling to obtain an anionic core-shell acrylic emulsion (1) having a core / shell solid content mass ratio of 40/60. It was. The non-volatile content of the obtained anionic core-shell type acrylic emulsion (1) was 25% by mass.

[Production Example 17] Production of anionic core-shell type acrylic emulsion (2) In a reaction vessel equipped with a stirrer, a thermometer, a dropping funnel, a reflux condenser, a nitrogen inlet, etc., 100 parts of deionized water and Production Example 1 33.3 parts of the obtained shell resin A was charged and heated to 80 ° C. while stirring.
A homogenizer was prepared by mixing 50.0 parts of the monomer mixture (II) obtained in Production Example 8, 53.3 parts of deionized water, and 133.3 parts of the shell resin A obtained in Production Example 1. To prepare a pre-emulsion solution. Subsequently, the prepared pre-emulsion was dropped into the reaction vessel with stirring for 3 hours.
In parallel with dropping of the pre-emulsion, an aqueous solution obtained by dissolving 0.3 part of ammonium persulfate as a polymerization initiator in 30 parts of water was maintained until the completion of dropping of the pre-emulsion while keeping the dropping rate constant. It was dripped in. After completion of dropping of the pre-emulsion, the reaction is further continued at 80 ° C. for 1 hour, followed by cooling to obtain an anionic core-shell acrylic emulsion (2) having a solid content mass ratio of 50/50 in the core part / shell part. It was. The non-volatile content of the obtained anionic core-shell type acrylic emulsion (2) was 25% by mass.

[Production Example 18] Production of anionic core-shell acrylic emulsion (3) Shell resin B obtained in Production Example 2 instead of Shell Resin D, Monomer mixture obtained in Production Example 10 instead of monomer mixture (II) An anionic core-shell acrylic emulsion (3) having a solid mass ratio of the core part / shell part of 50/50 was obtained in the same manner as in Production Example 17 except that (IV) was used.

[Production Example 19] Production of anionic core-shell type acrylic emulsion (4) In a reaction vessel equipped with a stirrer, a thermometer, a dropping funnel, a reflux condenser, a nitrogen inlet, etc., 100 parts of deionized water and Production Example 2 33.3 parts of the obtained shell resin B was charged and heated to 80 ° C. with stirring.
60.0 parts of the monomer mixture (III) obtained in Production Example 9, 76.7 parts of deionized water and 100.0 parts of the shell resin B obtained in Production Example 2 were mixed, and the homogenizer was mixed. To prepare a pre-emulsion solution. Subsequently, the prepared pre-emulsion was dropped into the reaction vessel with stirring for 3 hours.
In parallel with dropping of the pre-emulsion, an aqueous solution obtained by dissolving 0.3 part of ammonium persulfate as a polymerization initiator in 30 parts of water was maintained until the completion of dropping of the pre-emulsion while keeping the dropping rate constant. It was dripped in. After completion of dropping of the pre-emulsion, the reaction is further continued at 80 ° C. for 1 hour, followed by cooling to obtain an anionic core-shell acrylic emulsion (4) having a solid mass ratio of core / shell of 60/40. It was. The non-volatile content of the obtained anionic core-shell acrylic emulsion (4) was 25% by mass.

[Production Example 20] Production of anionic core-shell acrylic emulsion (5) Solid core / shell part in the same manner as in Production Example 19 except that the monomer mixture (IV) shown in place of the monomer mixture (III) was used. An anionic core-shell acrylic emulsion (5) having a mass ratio of 60/40 was obtained.

[Production Example 21] Production of an anionic core-shell type acrylic emulsion (6) In a reaction vessel equipped with a stirrer, thermometer, dropping funnel, reflux condenser, nitrogen inlet, etc., 100 parts of deionized water and Production Example 2 33.3 parts of the obtained shell resin B was charged and heated to 80 ° C. with stirring.
70.0 parts of the monomer mixture (I) obtained in Production Example 7 was mixed with 100 parts of deionized water and 66.7 parts of the shell resin B obtained in Production Example 2, and the mixture was emulsified with a homogenizer. Thus, a pre-emulsion solution was prepared. Subsequently, the prepared pre-emulsion was dropped into the reaction vessel with stirring for 3 hours.
In parallel with dropping of the pre-emulsion, an aqueous solution obtained by dissolving 0.3 part of ammonium persulfate as a polymerization initiator in 30 parts of water was maintained until the completion of dropping of the pre-emulsion while keeping the dropping rate constant. It was dripped in. After completion of dropping of the pre-emulsion, the reaction is further continued at 80 ° C. for 1 hour, followed by cooling to obtain an anionic core-shell acrylic emulsion (6) having a solid content mass ratio of 70/30 in the core part / shell part. It was. The non-volatile content of the obtained anionic core-shell acrylic emulsion (6) was 25% by mass.

[Production Examples 22 to 24] Production of anionic core-shell type acrylic emulsions (7) to (9) A shell resin shown in Table 1 instead of shell resin B and a monomer mixture shown in Table 1 instead of monomer mixture (I) Anionic core-shell acrylic emulsions (7) to (9) having a solid mass ratio of the core part / shell part of 70/30 were obtained in the same manner as in Production Example 21 except that they were used.

[Production Example 25] Production of anionic core-shell acrylic emulsion (10) In a reaction vessel equipped with a stirrer, thermometer, dropping funnel, reflux condenser, nitrogen inlet, etc., 100 parts of deionized water and Production Example 2 33.3 parts of the obtained shell resin B was charged and heated to 80 ° C. with stirring.
80.0 parts of the monomer mixture (III) obtained in Production Example 9 was mixed with 123.3 parts of deionized water and 33.3 parts of the shell resin B obtained in Production Example 2, and the homogenizer was mixed. To prepare a pre-emulsion solution. Subsequently, the prepared pre-emulsion was dropped into the reaction vessel with stirring for 3 hours.
In parallel with dropping of the pre-emulsion, an aqueous solution obtained by dissolving 0.3 part of ammonium persulfate as a polymerization initiator in 30 parts of water was maintained until the completion of dropping of the pre-emulsion while keeping the dropping rate constant. It was dripped in. After completion of dropping the pre-emulsion, the reaction is further continued at 80 ° C. for 1 hour, followed by cooling to obtain an anionic core-shell acrylic emulsion (10) having a solid content mass ratio of core / shell of 80/20. It was. The nonvolatile content of the obtained anionic core-shell acrylic emulsion (10) was 25% by mass.

[Production Example 26] Production of anionic core-shell acrylic emulsion (11) In a reaction vessel equipped with a stirrer, a thermometer, a dropping funnel, a reflux condenser, a nitrogen inlet, etc., 100 parts of deionized water and Production Example 2 33.3 parts of the obtained shell resin B was charged and heated to 80 ° C. with stirring.
90.0 parts of monomer mixture (I) obtained in Production Example 7 and 146.7 parts of deionized water were mixed and emulsified with a homogenizer to prepare a pre-emulsion solution. Subsequently, the prepared pre-emulsion was dropped into the reaction vessel with stirring for 3 hours.
In parallel with dropping of the pre-emulsion, an aqueous solution obtained by dissolving 0.3 part of ammonium persulfate as a polymerization initiator in 30 parts of water was maintained until the completion of dropping of the pre-emulsion while keeping the dropping rate constant. It was dripped in. After completion of dropping of the pre-emulsion, the reaction is further continued at 80 ° C. for 1 hour, followed by cooling to obtain an anionic core-shell acrylic emulsion (11) having a solid content mass ratio of 90/10 in the core / shell. It was. The non-volatile content of the obtained anionic core-shell type acrylic emulsion (11) was 25% by mass.

[Production Example 27] Production of cationic core-shell type acrylic emulsion (12) In a reaction vessel equipped with a stirrer, a thermometer, a dropping funnel, a reflux condenser, a nitrogen inlet, etc., 100 parts of deionized water and Production Example 5 The obtained shell resin E33.3 parts was charged and heated to 70 ° C. with stirring.
A homogenizer was prepared by mixing 50.0 parts of the monomer mixture (VIII) obtained in Production Example 14 with 53.3 parts of deionized water and 133.3 parts of the shell resin E 13 obtained in Production Example 5. To prepare a pre-emulsion solution. Next, 0.5 part of 2,2 ′ azobiz (2- (2-imidazolin-2-yl) propane) as a polymerization initiator was neutralized with 100% acetic acid, and an aqueous solution dissolved in 30 parts of water was put into the reaction vessel all at once. After the addition, the prepared pre-emulsion was dropped into the reaction vessel with stirring for 2 hours.
The reaction was further continued at 70 ° C. for 1 hour and then cooled to obtain a cationic core-shell type acrylic emulsion (12) having a core / shell part solid mass ratio of 50/50. The non-volatile content of the obtained cationic core-shell acrylic emulsion (12) was 25% by mass.

[Production Example 28] Production of cationic core-shell type acrylic emulsion (13) In a reaction vessel equipped with a stirrer, a thermometer, a dropping funnel, a reflux condenser, a nitrogen inlet, etc., 100 parts of deionized water and Production Example 4 33.3 parts of the obtained shell resin D was charged and heated to 70 ° C. while stirring.
60.0 parts of the monomer mixture (VI) obtained in Production Example 12, 76.7 parts of deionized water and 100.0 parts of the shell resin D obtained in Production Example 4 were mixed, and the homogenizer was mixed. To prepare a pre-emulsion solution. Next, 0.5 part of 2,2 ′ azobiz (2- (2-imidazolin-2-yl) propane) as a polymerization initiator was neutralized with 100% acetic acid, and an aqueous solution dissolved in 30 parts of water was put into the reaction vessel all at once. After the addition, the prepared pre-emulsion was dropped into the reaction vessel with stirring for 2 hours.
The reaction was further continued at 70 ° C. for 1 hour and then cooled to obtain a cationic core-shell type acrylic emulsion (13) having a core / shell part solid mass ratio of 60/40. The non-volatile content of the obtained cationic core-shell acrylic emulsion (13) was 25% by mass.

[Production Examples 29 to 30] Production of cationic core-shell type acrylic emulsions (14) to (15) The shell resin shown in Table 2 instead of the shell resin D and the monomer mixture shown in Table 2 instead of the monomer mixture (VI) Cationic core-shell type acrylic emulsions (14) to (15) having a solid mass ratio of the core part / shell part of 60/40 were obtained in the same manner as in Production Example 28, except that they were used.

[Production Example 31] Production of cationic core-shell type acrylic emulsion (16) In a reaction vessel equipped with a stirrer, a thermometer, a dropping funnel, a reflux condenser, a nitrogen inlet, etc., 100 parts of deionized water and Production Example 3 33.3 parts of the obtained shell resin C was charged, and the temperature was raised to 70 ° C. with stirring.
70.0 parts of the monomer mixture (V) obtained in Production Example 11 was mixed with 100 parts of deionized water and 66.7 parts of the shell resin C obtained in Production Example 3, and the mixture was emulsified with a homogenizer. Thus, a pre-emulsion solution was prepared. Next, 0.5 part of 2,2 ′ azobiz (2- (2-imidazolin-2-yl) propane) as a polymerization initiator was neutralized with 100% acetic acid, and an aqueous solution dissolved in 30 parts of water was put into the reaction vessel at once. After the addition, the prepared pre-emulsion was dropped into the reaction vessel with stirring for 2 hours.
The reaction was further continued at 70 ° C. for 1 hour, and then cooled to obtain a cationic core-shell type acrylic emulsion (16) having a core / shell part solids mass ratio of 70/30. The non-volatile content of the obtained cationic core-shell type acrylic emulsion (16) was 25% by mass.

[Production Examples 32-33] Production of cationic core-shell type acrylic emulsions (17)-(18) The shell resin shown in Table 2 instead of the shell resin C, and the monomer mixture shown in Table 2 instead of the monomer mixture (V) Cationic core-shell type acrylic emulsions (17) to (18) having a solid mass ratio of the core part / shell part of 70/30 were obtained in the same manner as in Production Example 31 except that they were used.

[Production Example 34] Production of cationic core-shell type acrylic emulsion (19) In a reaction vessel equipped with a stirrer, a thermometer, a dropping funnel, a reflux condenser, a nitrogen inlet, etc., 100 parts of deionized water and Production Example 4 33.3 parts of the obtained shell resin D was charged and heated to 70 ° C. while stirring.
80.0 parts of the monomer mixture (VI) obtained in Production Example 12 was mixed with 123.3 parts of deionized water and 33.3 parts of the shell resin D obtained in Production Example 4, and a homogenizer was mixed. To prepare a pre-emulsion solution. Next, 0.5 part of 2,2 ′ azobiz (2- (2-imidazolin-2-yl) propane) as a polymerization initiator was neutralized with 100% acetic acid, and an aqueous solution dissolved in 30 parts of water was put into the reaction vessel at once. After the addition, the prepared pre-emulsion was dropped into the reaction vessel with stirring for 2 hours.
The reaction was further continued at 70 ° C. for 1 hour, and then cooled to obtain a cationic core-shell acrylic emulsion (19) having a solid mass ratio of core / shell of 80/20. The non-volatile content of the obtained cationic core-shell acrylic emulsion (19) was 25% by mass.

[Production Examples 35 to 36] Production of cationic core-shell acrylic emulsions (20) to (21) The shell resin shown in Table 2 instead of the shell resin D, and the monomer mixture shown in Table 2 instead of the monomer mixture (VI) Cationic core-shell acrylic emulsions (20) to (21) having a solid mass ratio of the core part / shell part of 80/20 were obtained in the same manner as in Production Example 34, except for using.

[Examples 1 to 10] Preparation of transparent sealer composition For each of the anionic or cationic core-shell acrylic emulsions shown in Table 3, 50 parts of an anionic or cationic core-shell acrylic emulsion, 50 parts of water and CS-12 (Chisso) A transparent sealer composition was obtained by mixing 4 parts of Disper). About the obtained transparent sealer composition, the adhesiveness on an extrusion-molded cement board and the crack resistance of top coat film were evaluated. The results are shown in Table 3.

[Comparative Examples 1-2] Preparation of Transparent Sealer Composition For each of the anionic or cationic core-shell acrylic emulsions shown in Table 3, 50 parts of an anionic or cationic core-shell acrylic emulsion, 50 parts of water and CS-12 (Chisso) A transparent sealer composition was obtained by mixing 4 parts of Disper). About the obtained transparent sealer composition, the adhesiveness on an extrusion-molded cement board and the crack resistance of top coat film were evaluated. The results are shown in Table 3.

[Examples 11 to 13] Preparation of an anionic colored sealer composition An anionic colored sealer composition was prepared for each of the anionic core-shell acrylic emulsions shown in Table 4. The anionic colored sealer composition was prepared by the following method.
In the container, 170 parts of water and 10 parts of BYK190 (manufactured by Big Chemie Japan) were charged and stirred and mixed with a disper.
After the solution became uniform, 70 parts of titanium oxide Ti-PURE R706 (manufactured by DuPont) were mixed while stirring with a disper, and then stirring was continued for 10 minutes.
Next, 600 parts of an anionic core-shell type acrylic emulsion was gradually added, 40 parts of butyl cellosolve, 22 parts of Adecanol UH-420 (manufactured by Adeka) and 98 parts of water were added in this order, and the mixture was stirred for 5 minutes.
About the obtained anionic coloring sealer composition, the adhesiveness on an extrusion-molded cement board and the crack resistance of top coat film were evaluated. The results are shown in Table 4.

[Comparative Examples 3 to 4] Preparation of Anionic Colored Sealer Composition An anionic colored sealer composition was prepared for each of the anionic core-shell acrylic emulsions shown in Table 4. The anionic colored sealer composition was prepared in the same manner as in Examples 10-12. About the obtained anionic coloring sealer composition, the adhesiveness on an extrusion-molded cement board and the crack resistance of top coat film were evaluated. The results are shown in Table 4.

[Examples 14 to 16] Preparation of cationic colored sealer composition A cationic colored sealer composition was prepared for each of the cationic core-shell acrylic emulsions shown in Table 4. The cationic colored sealer composition was prepared by the following method.
In the container, 170 parts of water and 10 parts of EFKA4560 (manufactured by Ciba) were charged and stirred and mixed with a disper.
After the solution became uniform, 70 parts of titanium oxide Ti-PURE R706 (manufactured by DuPont) were mixed while stirring with a disper, and then stirring was continued for 10 minutes.
Next, 600 parts of a cationic core-shell acrylic emulsion is gradually added, and 40 parts of butyl cellosolve, 10 parts of Adecanol UH-762 (manufactured by Adeka), 2 parts of dehydran-1620 (manufactured by San Nopco), and 98 parts of water are added in order. And stirred for 5 minutes.
About the obtained cationic coloring sealer composition, the adhesiveness on an extrusion-molded cement board and the crack resistance of top coat film were evaluated. The results are shown in Table 4.

[Comparative Example 5] Preparation of cationic colored sealer composition A cationic colored sealer composition was prepared for each of the cationic core-shell acrylic emulsions shown in Table 4. The cationic colored sealer composition was prepared in the same manner as in Examples 13-15. About the obtained cationic coloring sealer composition, the adhesiveness on an extrusion-molded cement board and the crack resistance of top coat film were evaluated. The results are shown in Table 4.

[Production Example 37] Preparation of top coating composition a (low VOC water-based matt coating composition) Tap water 25.0 parts, SN Dispersant 5027 (Sannopco dispersant, solid content 20% by mass) 2.0 parts , Typek R820N (rutile titanium dioxide, manufactured by Ishihara Sangyo Co., Ltd.) 20.0 parts, heavy coal N (manufactured by Maruo Calcium Co., Heavy Calcium Carbonate) 29.0 parts, Satinton W Whitetex (clay, manufactured by Engelhard) 10.0 parts, SN deformer 154 (antifoam, manufactured by San Nopco) 0.2 part, 25% ammonia water 0.3 part, emulsion (acrylic resin emulsion (acid value 8, glass transition temperature-15 ° C., average particle) (Diameter 180 nm, solid content 50% by mass), made by Nippon Paint Co., Ltd.) 44.5 parts is mixed and stirred, and the pigment mass% (PWC) relative to the solid content is 72.1%. The top coating composition a was obtained.

  From Tables 3-4, it turns out that adhesiveness is so favorable that the solid content mass ratio of a shell part is high and the glass transition temperature (Tg) of a shell part is low. Moreover, it turns out that the crack resistance of top coat film is so favorable that the solid content mass ratio of a shell part is low and the glass transition temperature (Tg) of a core part and a shell part is high.

  Further, it is understood that the sealer coating film having both good adhesion and cracking resistance of the top coating film needs to appropriately adjust the glass transition temperature of the shell part / core part and the solid content mass ratio ( Examples 1-16). Thus, the composition containing the core-shell-type acrylic emulsion adjusted appropriately is excellent in adhesiveness and crack resistance, even if it contains the pigment (Examples 11-16).

  The method for forming a multilayer coating film of the present invention can be suitably used for coating exteriors of buildings, bridges, floors, building materials and the like.

Claims (3)

A multilayer coating film forming method for forming a coating film in the order of a sealer coating film and a top coating film on a base material or an old coating film,
A sealer composition for forming the sealer coating film,
The glass transition temperature of the core portion is 20 to 60 ° C., the glass transition temperature of the shell portion is 20 to 40 ° C., the glass transition temperature of the core portion is equal to or higher than the glass transition temperature of the shell portion, and the core portion / The core shell type acrylic emulsion whose solid content mass ratio of the shell part is 50/50 to 80/20,
A top coating composition for forming the top coating film is:
The VOC (volatile organic compound) content is a low VOC coating of 1% by mass or less based on the total amount of the top coating composition, and the total amount of solids in the top coating composition is Containing 70 to 90% by weight of pigment,
A method for forming a multilayer coating film.   The multilayer coating film forming method according to claim 1, wherein the core-shell type acrylic emulsion is cationic.   The method for forming a multilayer coating film according to claim 1, wherein the sealer composition does not contain a color pigment.