JP2007254623A - Weatherability-improving material for aqueous coating - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a weatherability-improving material applicable to various kinds of aqueous coatings while having high polymerization stability and storage stability, and capable of dramatically improving the weathering performance of such aqueous coatings. <P>SOLUTION: The weatherability-improving material is in the form of an aqueous dispersion of copolymer particles(α) obtained by multistep emulsion polymerization of ethylenically unsaturated monomers, meeting the following requirements: (1) A monomer mixture(A) to be subjected to polymerization at the final step contains (a) specific ethylenically unsaturated monomer having in the molecule a piperidyl group. (2) A monomer mixture(B) containing (c) a carboxyl-containing ethylenically unsaturated monomer is subjected to polymerization in a step prior to the final step. (3) The monomer mixture(A) accounts for 10-90 mass% of the total monomer to be used for the copolymer particles(α). (4) The monomer(a) accounts for 4.5-50 mass% of the total monomer to be used for the copolymer particles(α). (5) The final-step polymerization is conducted in the presence of 0.1-10 pts.mass of a chain-transfer agent. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a weather resistance improver for water-based paints, and more specifically to a water-based resin that can be improved in weather resistance such as gloss retention, yellowing resistance, and water resistance by adding to various water-based paints. It is a thing.

In recent years, in the paint field, conversion from a solvent-based paint using an organic solvent as a medium to an aqueous paint using water as a dispersion medium has been attempted in consideration of the global environment and the painting work environment. For this reason, the applications of water-based paints are rapidly expanding, and the performance required for water-based paints is becoming higher. Among such required performances, the weather resistance performance of the coating film is one of the most important performances, and the improvement is achieved by various means such as the inclusion of high weather resistance components such as silicone and fluorine.
On the other hand, the addition of weather resistance improvers such as ultraviolet absorbers, hindered amine type radical scavengers (hereinafter HALS), and antioxidants is used as an effective means for improving the weather resistance of various paints having different required performances. However, for water-based paints, since the main medium is water, when these are added, there is a problem in quality stability, such as floating in the upper layer of the system over time. Further, even when a film is formed using a water-based paint immediately after stirring, there is a problem that it is difficult to disperse uniformly in the coating film and sufficient performance is not exhibited. From such a point, the technique which disperse | distributes an additive in water beforehand using an emulsifier, and disperse | distributes uniformly in a coating film is proposed (refer patent document 1). However, in this case, the additive bleeds out over time, and it is difficult to maintain the weather resistance over a long period of time.
Technology to improve weather resistance by synthesizing high-concentration emulsion of reactive HALS with unsaturated double bond capable of radical polymerization in the molecule by multi-stage polymerization method and adding it to water-based paint Has been proposed (see Patent Document 2 and Patent Document 3). However, the copolymer obtained by this multi-stage polymerization method has a reactive HALS copolymerized at a high concentration in the outermost layer, so that a crosslinking reaction is likely to occur, resulting in a decrease in the diffusibility of the HALS component during film formation. There has been a problem that the types of water-based paints capable of obtaining sufficient weather resistance improving ability are limited. Further, depending on the concentration of reactive HALS in the outermost layer, there is a risk that sufficient polymerization stability and storage stability cannot be obtained.
Japanese Patent Publication No. 3-46506 JP 2004-10805 A JP 2004-292748 A

  The present invention has been made in view of the above circumstances, has high polymerization stability and storage stability, and can be applied to a very wide variety of water-based paints, and by adding a predetermined amount, An object of the present invention is to provide a weather resistance improving material for water-based paints that drastically improves the weather resistance performance of the water-based paint to be added, and to provide a highly weather-resistant water-based paint to which the weather resistance improver for water-based paints is added.

（Ｒ１は水素原子または炭素数１〜２のアルキル基、Ｘは酸素原子またはイミノ基、Ｙは水素原子または炭素数１〜２０のアルキル基またはアルコキシル基、Ｚは水素原子またはシアノ基を示す。） The gist of the present invention is an aqueous dispersion of copolymer particles (α) obtained by multistage emulsion polymerization of an ethylenically unsaturated monomer, which satisfies the following conditions (1) to (5) It is in the weather resistance improving material.
(1) An ethylenically unsaturated monomer having a piperidyl group in the molecule, wherein the ethylenically unsaturated monomer mixture (A) polymerized at the final stage in multi-stage emulsion polymerization is represented by the following general formula (I) From (a) 5 to 60% by mass and ethylenically unsaturated monomer other than the monomer (a) (b) 40 to 95% by mass (provided the total of (a) and (b) is 100% by mass) To become a.
(2) The ethylenically unsaturated monomer mixture (B) containing the carboxyl group-containing ethylenic monomer (c) is polymerized at any stage before the final stage.
(3) The content of the ethylenically unsaturated monomer mixture (A) in the total ethylenically unsaturated monomers used for the copolymer particles (α) is 10 to 90% by mass (however, the copolymer particles (The sum of all ethylenically unsaturated monomers used in (α) is 100% by mass).
(4) The content of the ethylenically unsaturated monomer (a) in the total ethylenically unsaturated monomer used for the copolymer particles (α) is 4.5 to 50% by mass (however, the copolymer The total of all ethylenically unsaturated monomers used in the particles (α) is 100% by mass).
(5) When the ethylenically unsaturated monomer mixture (A) is 100 parts by mass, the final polymerization is performed in the presence of 0.1 to 10 parts by mass of the chain transfer agent.

(R1 represents a hydrogen atom or an alkyl group having 1 to 2 carbon atoms, X represents an oxygen atom or imino group, Y represents a hydrogen atom or an alkyl group or alkoxyl group having 1 to 20 carbon atoms, and Z represents a hydrogen atom or a cyano group. )

  According to the present invention, when added to a water-based paint, there is almost no bleed-out from the coating film, and the weather resistance improver for water-based paints that drastically improves the weather resistance such as gloss retention, yellowing resistance and water resistance. Can provide.

The weather resistance improving material for water-based paints of the present invention is an aqueous dispersion of copolymer particles (α) obtained by multistage emulsion polymerization of an ethylenically unsaturated monomer.
In the production of the weather resistance improver for water-based paints of the present invention, the ethylenically unsaturated monomer mixture (A) for the final stage of the multi-stage emulsion polymerization is a heavy component constituting the water paint to which the weather resistance improver for water paints is added. From the standpoint of compatibility with coalescence and expression of weather resistance of the coating film, when the total amount of monomers constituting the monomer mixture (A) is 100% by mass, the ethylenic property represented by the general formula (I) The unsaturated monomer (a) needs to be in the range of 5 to 60% by mass. When the content of the monomer (a) is less than 5% by mass, even if the ratio of the monomer mixture (A) in the copolymer particles (α) is increased to the maximum, the monomer (a) Since the concentration becomes low, in order to sufficiently improve the weather resistance, it is necessary to add a large amount of the weather resistance improving material for water-based paints, which causes a great change in paint properties and coating film properties, which is not preferable. Moreover, when more than 60 mass%, sufficient compatibility may not be acquired depending on the kind of water-based paint which reduces polymerization stability and storage stability and adds the said weather-resistance improving material for water-based paints. The content of the monomer (a) is more preferably 10 to 50% by mass. As the monomer (a), one having an ultraviolet light stabilizing function can be used. For example, 4- (meth) acryloyloxy-2,2,6,6-tetramethylpiperidine, 4- (meth) Acryloylamino-2,2,6,6-tetramethylpiperidine, 4- (meth) acryloyloxy-1,2,2,6,6-pentamethylpiperidine, 4- (meth) acryloylamino-1,2,2 , 6,6-pentamethylpiperidine, 4-cyano-4- (meth) acryloyloxy-2,2,6,6-tetramethylpiperidine and the like. These may be used alone or in combination of two or more as required. It is possible to use the methacrylate monomer in which R1 in the general formula (I) is a methyl group as the monomer (a), alone or in combination of two or more thereof, the weather resistance of the water-based paint containing the water-resistant paint for water-based paints It is particularly preferable from the viewpoint of improving the properties.

  As the ethylenically unsaturated monomer (b) other than the monomer (a) constituting the monomer mixture (A), depending on the water-based paint to which the weather-resistance improving material for water-based paint is added, such a water-based paint It is most preferable to use the main monomers constituting the resin alone or in combination of two or more from the viewpoint of maintaining various properties of the aqueous paint to which the weather resistance improver for water paint is added, but it is not limited thereto. Absent. Examples of the monomer (b) include methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, i-propyl (meth) acrylate, n-butyl (meth) acrylate, and i-butyl. (Meth) acrylate, sec-butyl (meth) acrylate, t-butyl acrylate, n-amyl (meth) acrylate, i-amyl (meth) acrylate, n-hexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, Alkyl having 1 to 17 carbon atoms such as n-octyl (meth) acrylate, nonyl (meth) acrylate, decyl (meth) acrylate, dodecyl (meth) acrylate, lauryl (meth) acrylate, stearyl (meth) acrylate (Meth) acrylates; Cycloalkyl (meth) acrylates such as hexyl (meth) acrylate and pt-butylcyclohexyl (meth) acrylate; 2-hydroxyethyl (meth) acrylate, 2- (3-) hydroxypropyl (meth) acrylate, 4- Hydroxyl group-containing radical polymerizable monomers such as hydroxybutyl (meth) acrylate and glycerol mono (meth) acrylate; (meth) acrylamide, N, N-dimethylaminoethyl (meth) acrylate, vinylpyridine, vinylimidazole, etc. Nitrogen-containing polymerizable monomers; halogen-containing monomers such as vinyl chloride, vinylidene chloride, vinyl fluoride, vinylidene fluoride, tetrafluoroethylene; aromatic monomers such as styrene, α-methylstyrene, vinyltoluene; Vinyl esters such as vinyl acetate Vinyl ether; polymerizable cyanide such as (meth) acrylonitrile, carboxyl such as (meth) acrylic acid, crotonic acid, itaconic acid, monomethyl itaconate, monobutyl itaconate, fumaric acid, maleic acid, monomethyl maleate, monobutyl maleate Group-containing monomers; sulfonic acid group-containing monomers such as vinyl sulfonic acid, styrene sulfonic acid and sulfoethyl (meth) acrylate; 2- (meth) acryloyloxyethyl acid phosphate, 2- (meth) acryloyloxypropyl acid Use acidic functional group-containing unsaturated monomers such as phosphate, 2- (meth) acryloyloxy-3-chloropropyl acid phosphate, and acid phosphate monomers such as 2-methacryloyloxyethylphenyl phosphate Can do. The said monomer can be used individually or in combination of 2 or more types. Among these, it is preferable to use a (meth) acrylic ester unsaturated monomer from the viewpoint of improving the weather resistance of the water-based paint including the weather resistance improver for water-based paints of the present invention. Moreover, what is necessary is just to select a monomer (b) according to a required performance, when providing performances other than a weather resistance to aqueous resin. Moreover, it can be easily imagined that the ability to improve weather resistance is further improved by copolymerizing with a reactive UVA having a functional group having an ultraviolet absorbing ability in the measuring chain. Moreover, as described later, it is preferable to polymerize the acidic functional group-containing unsaturated monomer at a stage other than the polymerization of the monomer (a). When the acidic functional group-containing unsaturated monomer is polymerized together with the monomer (a), the amount of the acidic functional group-containing unsaturated monomer should be kept as small as possible and polymerized with a sufficient amount of emulsifier. Is preferable from the viewpoint of polymerization stability. In this case, the amount of the acidic functional group-containing unsaturated monomer is preferably 0.2% or less from the viewpoint of polymerization stability, and particularly preferably not substantially contained.

  Moreover, the weather resistance improving material for water-based paints of the present invention polymerizes an ethylenically unsaturated monomer mixture (B) containing a carboxyl group-containing ethylenically unsaturated monomer (c) as an essential component in the final stage. It is necessary to polymerize in advance. When the carboxyl group-containing ethylenically unsaturated monomer (c) is not included as an essential component, it may not exhibit high storage stability and mechanical stability. As the carboxyl group-containing ethylenically unsaturated monomer (c), (meth) acrylic acid, crotonic acid, itaconic acid, itaconic acid monomethyl, itaconic acid monobutyl, fumaric acid, maleic acid, monomethyl maleate, monobutyl maleate, etc. Can be used. The amount of the carboxyl group-containing ethylenically unsaturated monomer (c) is not particularly specified, but it is 0.2% by mass or more in the copolymer particles (α) in terms of mechanical stability and storage stability of the particles. To preferred. When the ethylenically unsaturated monomer mixture (B) containing these carboxyl group-containing ethylenically unsaturated monomers (c) is polymerized, it is neutralized by adding a basic compound before the final polymerization. From the viewpoint of polymerization stability, it is preferable to adjust the pH to 4.0 or higher in advance, and it is particularly preferable to adjust the pH to 7 or higher. Examples of basic compounds used for neutralization include ammonia, triethylamine, propylamine, dibutylamine, amylamine, 1-aminooctane, 2-dimethylaminoethanol, ethylaminoethanol, 2-diethylaminoethanol, 1-amino-2- Propanol, 2-amino-1-propanol, 2-amino-2-methyl-1-propanol, 3-amino-1-propanol, 1-dimethylamino-2-propanol, 3-dimethylamino-1-propanol, 2- Examples include propylaminoethanol, ethoxypropylamine, aminobenzyl alcohol, morpholine, sodium hydroxide, potassium hydroxide and the like.

  The resistance improving material of the present invention has a monomer mixture (A) content of 10 when the total of all ethylenically unsaturated monomers used in the copolymer particles (α) is 100% by mass. It needs to be -90 mass%. When the content of the monomer mixture (A) is less than 10% by mass, the monomer (a) in the copolymer particles (α) has a low concentration, so that the weather resistance can be sufficiently improved. Therefore, it is necessary to add a large amount of the weather resistance improving material for water-based paints, which causes undesirable changes in paint properties and coating film properties. In addition, when the content of the monomer mixture (A) exceeds 90%, the monomer mixture containing the carboxyl group-containing ethylenically unsaturated monomer (c) in the stage before polymerizing the monomer mixture (A). Even when (B) is polymerized, the amount of carboxyl groups contributing to the stability of the particles on the surface of the particles after polymerization of the monomer mixture (A) is reduced, resulting in problems in mechanical stability and storage stability. There is a case.

  Moreover, when the total of all the ethylenically unsaturated monomers used for the copolymer particles (α) is 100% by mass, the weather resistance improving material for water-based paints of the present invention contains the monomer (a). The amount needs to be in the range of 4.5-50% by weight. When the content of the monomer (a) is less than 4.5% by mass, in order to sufficiently improve the weather resistance of the water-based paint containing the weather-resistance improving material for water-based paint, It is necessary to add a large amount of an improving material, which causes a great change in the physical properties of the paint and the coating film, which is not preferable. Moreover, when more than 50 mass%, sufficient compatibility may not be acquired depending on the kind of aqueous coating material which adds the said weather resistance improving material for the said aqueous coating materials while reducing polymerization stability and storage stability. A more preferable content is 10 to 50% by mass.

  In addition, when the total amount of monomers constituting the final-stage ethylenically unsaturated monomer mixture (A) used in the weather resistance improver for water-based paints of the present invention is 100 parts by mass, chain transfer agent 0. It is necessary to polymerize together with 1 to 10 parts by mass. When the amount of the chain transfer agent is less than 0.1 parts by mass, depending on the content of the monomer (a) in the monomer mixture (A), a polymer having a high crosslinking density is formed, and this In the film-forming process of the water-based paint containing a weather resistance improving material, high diffusibility of the functional group having the weather resistance improving ability cannot be obtained, and the sufficient weather resistance improving ability may not be exhibited. When the amount of the chain transfer agent exceeds 10 parts by mass, the molecular weight of the polymer containing the monomer (a) is remarkably reduced, and the same phenomenon as that of the non-reactive HALS, that is, the ability to improve weather resistance by bleeding out from the coating film. In addition to the limited period during which this occurs, the water resistance of the water-based paint containing the weather resistance improver for the water-based paint may also be lowered due to the influence of the residual chain transfer agent. The amount of chain transfer agent is more preferably 0.1 to 8% by mass, and particularly preferably 0.1 to 6% by mass. Examples of chain transfer agents include mercaptans such as n-dodecyl mercaptan, t-dodecyl mercaptan, n-octyl mercaptan, t-octyl mercaptan, n-tetradecyl mercaptan, n-hexyl mercaptan, n-butyl mercaptan; carbon tetrachloride, Examples include halogen compounds such as ethylene bromide; and known chain transfer agents such as α-methylstyrene dimer. The chain transfer agents can be used alone or in combination of two or more.

  Moreover, as an emulsifier used when carrying out emulsion polymerization of the copolymer particle ((alpha)) used for the weather-resistance improving material for water-based paints of this invention, conventionally various anionic non-reactive emulsifiers and nonionic property are used. Non-reactive emulsifiers, polymer emulsifiers, and the like, and when used together with these non-reactive emulsifiers and reactive emulsifiers having unsaturated double bonds capable of radical polymerization in the molecule, the weather resistance for water-based paints of the present invention In a water-based paint containing an improver, higher water resistance and weather resistance can be obtained, and when polymerized only with a reactive emulsifier, the effect becomes more remarkable. Examples of reactive emulsifiers include trade names “Adekaria Soap SR-10” and “SE-10” manufactured by Asahi Denka Co., Ltd., trade names “Aqualon KH-05” and “KH-10” manufactured by Daiichi Kogyo Seiyaku Co., Ltd. Reactive anionic emulsifiers such as “Adekaria Soap NE-10”, “Same ER-10”, “Same NE-20”, “Same ER” manufactured by Asahi Denka Co., Ltd. -20 "," NE-30 "," ER-30 "," NE-40 "," ER-40 ", trade names" AQUALON RN-10 "," RN " Reactive nonionic emulsifiers such as "-20", "RN-30", and "RN-50". These may be used alone or in combination of two or more as required. It is preferable to use a reactive anionic emulsifier and a reactive nonionic emulsifier in combination for applications requiring particularly high mechanical stability. The amount of the emulsifier is not particularly defined, but from the viewpoint of weather resistance and water resistance of the aqueous paint containing the weather resistance improving material for water paint of the present invention, when the total monomer is 100 parts by mass, It is preferably used within the range of 10 parts by mass. In the present invention, the unsaturated monomer does not contain a reactive emulsifier.

The copolymer particles (α) used in the weather resistance improver for water-based paints of the present invention can be prepared by using an ethylenically unsaturated monomer and emulsion polymerization using a radical polymerization initiator. . The copolymer particles (α) have a multilayer structure having a two-layer structure or more, but preferably have a three-layer structure or less from the viewpoint of production efficiency and particle diameter control.
As the polymerization initiator for polymerizing the copolymer particles (α) used for the weather resistance improving material for water-based paints of the present invention, those generally used for radical polymerization can be used, and specific examples thereof are as follows. Are persulfates such as potassium persulfate, sodium persulfate, ammonium persulfate; azobisisobutyronitrile, 2,2′-azobis (2-methylbutyronitrile), 2,2′-azobis (2,4 Oil-soluble azo compounds such as 2-dimethylvaleronitrile), 2,2′-azobis (4-methoxy-2,4-dimethylvaleronitrile), 2-phenylazo-4-methoxy-2,4-dimethylvaleronitrile; 2 , 2′-azobis {2-methyl-N- [1,1-bis (hydroxymethyl) -2-hydroxyethyl] propionamide}, 2,2′-azobis {2-methyl-N- [2- ( 1-hydroxyethyl)] propionamide}, 2,2′-azobis {2-methyl-N- [2- (1-hydroxybutyl)] propionamide}, 2,2′-azobis [2- (5-methyl) -2-imidazolin-2-yl) propane] and salts thereof, 2,2′-azobis [2- (2-imidazolin-2-yl) propane] and salts thereof, 2,2′-azobis [2- (3 , 4,5,6-tetrahydropyrimidin-2-yl) propane] and salts thereof, 2,2′-azobis {2- [1- (2-hydroxyethyl) -2-imidazolin-2-yl] propane} and Its salts, 2,2′-azobis (2-methylpropionamidine) and its salts 2,2′-azobis (2-methylpropyneamidine) and its salts, 2,2′-azobis [N- (2-cap Water-soluble azo compounds such as (Boxyethyl) -2-methylpropionamidine] and salts thereof; benzoyl peroxide, cumene hydroperoxide, t-butyl hydroperoxide, t-butylperoxy-2-ethylhexanoate, t- And organic peroxides such as butyl peroxyisobutyrate. These initiators can be used alone or as a mixture of two or more. Further, when acceleration of the polymerization rate and low temperature polymerization at 70 ° C. or lower are desired, it is advantageous to use a reducing agent such as sodium bisulfite, ferrous sulfate, ascorbate in combination with the radical polymerization catalyst. .
The addition amount of the radical polymerization initiator is usually in the range of 0.01 to 10% by mass with respect to the total amount of the ethylenically unsaturated monomer, but considering the content of the monomer (a) and the like. What is necessary is just to change so that it may become in the range of the said weight average molecular weight.

  In addition, the molecular weight of the polymer in each polymerization stage for forming the copolymer particles (α) used in the weather resistance improver for water-based paints of the present invention is not particularly defined, but the polymer containing the monomer (a), The weight average molecular weight (Mw) of the polymer polymerized at the final stage is preferably 5,000 or more. When the weight average molecular weight (Mw) of the polymer containing the monomer (a) is less than 5,000, the polymer containing (a) that contributes to improving weather resistance includes the weather resistance improving material for water-based paints. There is a case where the period of bleeding out from the coating film of the water-based paint and the development of the weather resistance improving ability is limited. Moreover, it is preferable that the weight average molecular weight (Mw) of the polymer which does not contain a monomer (a), ie, the polymer of the part superposed | polymerized before the last stage, is 15,000 or more. When the weight average molecular weight (Mw) of the polymer not containing the monomer (a) is less than 15,000, the weather resistance of the water-based resin containing the weather resistance improving material for water-based paints may not be sufficiently improved. The monomer (a) is preferably prepared while considering the balance of the weight average molecular weight (Mw) film-forming property and compatibility. Further, the polymer average molecular weight (Mw) of the polymer containing the monomer (a) and the polymer not containing the monomer (a), that is, all the polymers forming the copolymer particles (α) is 10, 000 or more is preferable. Even when the weight average molecular weight (Mw) is less than 10,000, the weather resistance improving ability of the water-based paint including the weather resistance improving material for water-based paint may not be sufficiently exhibited.

  The particle diameter of the copolymer particles (A) used for the weather resistance improving material for water-based paints of the present invention is not particularly limited, but is preferably 300 nm or less in terms of weight average particle diameter. When the weight average particle diameter exceeds 300 nm, the functional group having radical trapping ability cannot be sufficiently diffused depending on the type of water-based paint to which the weather resistance improving material of the present invention is added and the film forming conditions. There may be cases where improved performance is not exhibited. As a weight average particle diameter, 170 nm or less is more preferable, and 140 nm or less is especially preferable. Moreover, in order to prevent the water resistance fall by the increase in an emulsifier, it is preferable that a weight average particle diameter is 30 nm or more.

Further, the glass transition temperature of the polymer containing the monomer (a) and the polymer containing the monomer (c) constituting the copolymer particles (α) used for the weather resistance improving material for water-based paints of the present invention. (Tg) is not particularly defined, but it is preferably 100 ° C. or lower in any polymer. In particular, when the glass transition temperature (Tg) of the polymer containing the monomer (a) exceeds 100 ° C., in the aqueous paint containing the weather resistance improving material of the present invention, sufficient film-forming property may not be obtained. It can be a factor that reduces water resistance and weather resistance. The glass transition temperature (Tg) of the polymer containing the monomer (a) and the polymer containing the monomer (c) is preferably 70 ° C. or lower, and more preferably 50 ° C. or lower. In addition, as said glass transition temperature (Tg), the calculated glass transition temperature calculated | required by the formula of Fox is used. The Fox formula is a relational expression between the glass transition temperature (° C.) of a copolymer and the glass transition temperature (° C.) of a homopolymer obtained by homopolymerizing each of the copolymer monomers as shown below.
1 / (273 + Tg) = Σ (Wi / (273 + Tgi))
[In the formula, Wi represents the mass fraction of monomer i, and Tgi represents the Tg (° C.) of the homopolymer of monomer i. ]
In addition, as Tg of a homopolymer, the value specifically described in "Polymer Handbook 3rd Edition" (A WILEY-INTERSCIENCE PUBLICATION, 1989) can be used.

  The weather resistance improving material for water-based paints of the present invention is made slightly alkaline by adding a basic compound after polymerization, ie, pH 7.5 to 10. The stability of the system can be improved by adjusting to a range of about 0. Examples of the basic compound include ammonia, triethylamine, propylamine, dibutylamine, amylamine, 1-aminooctane, 2-dimethylaminoethanol, ethylaminoethanol, 2-diethylaminoethanol, 1-amino-2-propanol, 2 -Amino-1-propanol, 2-amino-2-methyl-1-propanol, 3-amino-1-propanol, 1-dimethylamino-2-propanol, 3-dimethylamino-1-propanol, 2-propylaminoethanol , Ethoxypropylamine, aminobenzyl alcohol, morpholine, sodium hydroxide, potassium hydroxide and the like. In the case of interior use where it is desired not to include VOC, it is preferable to use an inorganic base compound. Furthermore, when it is desired that there is no slight odor, it is preferable to use a non-volatile inorganic base compound such as sodium hydroxide or potassium hydroxide.

The weather resistance improver for water-based paints of the present invention is usually used in the range of 20 to 80 parts by mass of solid content, but is not limited thereto, and the weather resistance improver for water-based paints of the present invention is added. What is necessary is just to use it according to the viscosity of the water-based paint to make. The weather resistance improving material for water-based paints of the present invention can be used for various water-based paints such as (meth) acrylic, urethane-based, polyester-based, epoxy-based, alkyd-based, etc. Depending on the amount of addition, the amount added can be changed. Although it does not prescribe | regulate especially about the addition amount, It is preferable to use in 1-50 mass parts with respect to a to-be-added water-based coating material. If the addition amount is less than 1 part by mass, the weather resistance performance of the water-based paint containing the water-proof paint weathering improver may not be sufficiently improved. When the amount exceeds 50 parts by mass, there is a risk that one or more of the characteristics of the water-based paint including the weather resistance improving material for water-based paints of the present invention will be significantly reduced. Moreover, the weather resistance improving material for water-based paints of the present invention may be used alone or in combination of two or more resins having the same composition. In addition, in order to develop high performance in the weather resistance improving material for water-based paints of the present invention and water-based paints containing the same, various pigments, antifoaming agents, pigment dispersants, leveling agents, anti-sagging agents, matting agents, Non-reactive HALS, non-reactive UV absorbers, antioxidants, heat resistance improvers, slip agents, preservatives, and the like may be added.
In order to form a coating film on the surface of various materials using the water-based paint containing the weather resistance improver for water-based paints of the present invention, for example, spray coating method, roller coating method, bar coating method, air knife coating method, brush What is necessary is just to implement suitably selecting well-known coating methods, such as a coating method and a dipping method.

EXAMPLES Hereinafter, although an Example demonstrates this invention further in detail, this invention is not limited at all by these. In the following description, “part” is based on mass.
Examples 1 to 10 and Comparative Examples 1 to 11 relate to a water-based resin evaluated as a weather resistance improver for water-based paints, and Production Examples 1 to 5 relate to a water-based resin serving as a base of the water-based paint. For evaluation as these aqueous resins, the following items were tested according to the following method.
<Test method>
(1) Mechanical stability test With respect to the aqueous resins of Examples 1 to 10, Comparative Examples 1 to 11 and Production Examples 1 to 5, 100 g of each was tested for 20 minutes using a Malone testing machine with a share of 15 kg, and 100 The mixture was filtered through a mesh nylon basket, the amount of the residue was measured, and evaluated according to the following criteria.
“◎”: The amount of the residue is 0.01 g or less or hardly seen.
"(Circle)": The quantity of a residue is 0.01-0.1g.
“Δ”: The amount of the residue is 0.1 to 0.5 g.
“X”: The amount of the residue is 0.5 g or more, or gels during the test.
(2) Storage stability About the aqueous resin of Examples 1-10, Comparative Examples 1-11, and Production Examples 1-5, 200g of each is put into a glass bottle, and it puts into a 50 degreeC thermostat for 2 weeks. Thereafter, the product was taken out, the presence / absence of a coagulated product and the viscosity were confirmed, and evaluated according to the following criteria.
“◎”: There is no coagulum, and the rate of change in viscosity is within ± 20%.
“◯”: There is no coagulum, and the rate of change in viscosity is ± 20% or more and ± 35% or less.
“Δ”: There is no coagulum, and the rate of change in viscosity is ± 20% or more and ± 50% or less.
"X": A coagulum is seen.

(3) Polymerization stability In Examples 1 to 10, Comparative Examples 1 to 11, and Production Examples 1 to 5, cullet during polymerization was collected by filtration with a 100 mesh nylon basket and dried in a drying oven at 50 ° C. for 24 hours. The weight was measured and evaluated according to the following criteria.
“◎”: The amount of cullet in the dry state is 100 ppm or less.
“◯”: The amount of cullet in the dry state is 100 ppm or more and 1000 ppm or less.
“Δ”: The amount of cullet in the dry state is 1000 ppm or more, but polymerization is possible.
“×”: Polymerization is impossible due to instability.
(4) Weight average molecular weight (Mw)
About Examples 1-10, Comparative Examples 1-11, and Production Examples 1-5, 0.1g of each is extract | collected to a sample bottle, tetrahydrofuran (THF) 10g is added, and it is left overnight at room temperature. The prepared sample solution was measured using the HLC-8120 manufactured by Tosoh Corporation under the following conditions to obtain a weight average molecular weight (Mw) in terms of standard polystyrene.
Column: TSK-gel TSL-gel SuperHM-M x 4 (6.0mmI.D. x 15cmL)
Eluent: THF
Flow rate: 0.6ml / min
Injection volume: 20μl
Column temperature: 40 ° C
Detector: RI

(5) Solubility test For Examples 1 to 10 and Comparative Examples 1 to 11, the total amount of the sample eluted from the separation column by GPC measurement was recovered, and the THF solvent was removed by volatilization, followed by pyrolysis gas chromatograph / mass spectrometry. The qualitative analysis of dissolved components was performed using The device name, conditions, etc. are as follows.
Apparatus: Gas chromatograph mass spectrometer: 6890 / 5973N made by Agilent Technologies
Pyrolysis device: Double Shot Pyrolyzer PY-2010D manufactured by Frontier Laboratories
Separation column: Metal capillary column UA-5 manufactured by Frontier Laboratories
30 m × 0.25 mm i.d. Film thickness: 0.25 μm
Thermal decomposition temperature: 550 ° C
Inlet temperature: 300 ° C
Oven temperature: 40 ° C. (2 minutes hold) → Temperature rise at 10 ° C./minute→300° C. (10 minutes hold)
Carrier gas: Helium Gas flow rate: 1.0 ml / min (constant flow)
Ionization method: Electron impact ionization method Detection mode: Scan mode Scan range (m / z): 33 to 500

When the components eluted under the above analysis conditions were analyzed, the eluted components could be divided into three types. That is, first, the component eluted from the GPC is almost identical to the composition obtained by recovering the copolymer particles (α), and the polymer containing the monomer (a) and the monomer (c) The composition is a combination of the polymers to be contained, and it is considered that all the polymers constituting the copolymer particles (α) are dissolved. Second, it is determined that the recovered component does not substantially contain the monomer (a), and the polymer containing the monomer (a) forms a crosslinked structure or has an ultrahigh molecular weight. On the other hand, the polymer containing the monomer (c) is judged to be soluble in the solvent. Thirdly, the content of monomer (c) is small, but the ratio of monomer (a) is high, and the polymer containing monomer (c) is insolubilized by the crosslinking agent. The polymer containing the monomer (a) is judged to be soluble in the solvent. Considering the above results, solubility was evaluated according to the following criteria.
(A): It is judged that both the polymer containing the monomer (a) and the polymer containing the monomer (c) are soluble.
(B): The polymer containing the monomer (c) is soluble, but the polymer containing the monomer (a) is judged to be substantially insoluble.
(C): The polymer containing the monomer (c) is substantially insoluble, but the polymer containing the monomer (a) is judged to be soluble.
(D): There is almost no elution component from GPC, and it is judged that both the polymer containing monomer (a) and the polymer containing monomer (c) are insoluble.

About the test as a water-based paint, after preparing the coating material for film-forming by the following method, the test was implemented according to the following method.
<Preparation of clear paint>
The water-based resins of Examples 1 to 10 and Comparative Examples 1 to 11 are blended at the ratios shown in Table 2 below with respect to the base resins for various water-based paints of Production Examples 1 to 5. To 100 g of the prepared base resin for weather resistance evaluation, add “CS-12” (trade name, manufactured by Chisso Corporation, film-forming aid) as a film-forming aid until the minimum film-forming temperature is 5 ° C., 10 g of “SP Seal H” (trade name, manufactured by Kaleido Co., Ltd., silica-based matting agent), 0.5 g of “RHEOLATE 350” (trade name, manufactured by RHEOX Co., Ltd., thickener), “Surfinol DF-58 (Trade name, manufactured by Air Products Co., Ltd., antifoaming agent) was added in an amount of 0.5 g, and the mixture was sufficiently stirred and filtered using a 100 mesh nylon bag to obtain a clear paint for evaluation.
<Creation of clear test plate>
The paint prepared above is spray-coated on a zinc phosphate-treated steel plate (Bondelite # 100-treated steel plate, plate thickness 0.8 mm, 70 mm × 150 mm) to a dry film thickness of 50 μm, and then left at room temperature for 1 hour. And what was forced-dried at 80 degreeC for 1 hour was made into the test coating board of a weather resistance test and a weather resistance improvement test.
<Preparation of white enamel paint>
"Taipeku CR-97" (trade name, manufactured by Ishihara Sangyo Co., Ltd., chlorinated titanium oxide) 707g, "ADEKA COAL W-193" (trade name, manufactured by Asahi Denka Kogyo Co., Ltd., pigment dispersant) 12g, "Surfi Nord DF-58 "(trade name, manufactured by Air Products Co., Ltd., defoaming agent) 25 g and deionized water 256 g are thoroughly mixed, glass beads are added, and pigment dispersion is performed with a high-speed disperser for 30 minutes. Glass beads and the like were separated by filtration with a 300 mesh nylon basket to obtain a mill base for evaluation (solid content: 71% by mass).
Next, 100 g of a weather resistance evaluation base resin in which the aqueous resins of Examples 1 to 10 and Comparative Examples 1 to 11 were blended at the ratios shown in Table 2 below with respect to the various aqueous coating base resins of Production Examples 1 to 5. (CS-12) (trade name, manufactured by Chisso Co., Ltd., film-forming aid) is added as a film-forming aid to (solid content of 50% by mass basis) until the minimum film-forming temperature is 5 ° C. Add 47g of mill base for evaluation and 0.5g of "RHEOLATE350" (trade name, manufactured by RHEOX Co., Ltd., thickener) in order, stir well, and remove with Ford Cup # 4 for about 30 seconds. Ionized water was added for adjustment. Thereafter, filtration was again performed using a 300-mesh nylon bag to obtain a white enamel paint for evaluation with PWC = 40%.
<Creation of enamel test plate>
The zinc phosphate-treated steel plate (“Bondelite” # 100-treated steel plate, plate thickness 0.8 mm, 70 mm × 150 mm) is spray-coated with the paint prepared above to a dry film thickness of 50 μm, and then 1 at room temperature. What was left standing for an hour and forcedly dried at 80 ° C. for 1 hour was used as a test coated plate for a weather resistance test, a choking test, a weather resistance improvement test, and a pigment dispersibility test.

(6) Weather resistance test The test coating plate prepared above is put in an evaluation apparatus “Daipura Metal Weather KU-R4-W” (trade name: manufactured by Daipura Wintes Co., Ltd.), and a test cycle: Irradiation 6 hours / condensation 2 hours, UV intensity: 85 mW / cm 2, black panel temperature: 63 ° C. during irradiation / 30 ° C. during condensation, humidity: 50% RH during irradiation / 96% RH during condensation, after 1500 hours The gloss retention of 60 ° gloss was used as a weather resistance index, and the following criteria were used.
In addition, 60 degree gloss was measured using the Nippon Denshoku Industries Co., Ltd. change gloss meter "VG-2000 type".
“◎”: 80% or more.
“◯”: 70% or more and less than 80%.
“◯ △”: 60% or more and less than 70%.
“△”: 50% or more and less than 60%.
“X”: 30% or more and less than 50%.
“XX”: Less than 30%.
(7) Water resistance test A clear paint was applied on a glass plate using an 8MIL applicator, then dried at room temperature for 1 hour, and then forcibly dried at 80 ° C for 1 hour. It was. The evaluation coated plate was immersed in water at room temperature (about 20 ° C.) for 1 week. The whitening of the paint film immediately after removal was visually confirmed and judged according to the following criteria.
“◎”: no whitening is observed.
“O”: Slight whitening is observed.
“△”: Whitening is observed.
“×”: Remarkable whitening is observed.

(8) Compatibility test A clear paint was applied on a glass plate using an 8MIL applicator, then dried at room temperature for 1 hour, and then forcibly dried at 80 ° C for 1 hour. did. The state of the coating film was visually confirmed and judged according to the following criteria.
“O”: No haze is confirmed.
“Δ”: Slight haze is observed.
“×”: Remarkable haze is observed.
(9) Choking test The choking state of the coating film after the 2000 hour acceleration test was visually evaluated and judged according to the following criteria.
“O”: No choking.
“△”: Slight choking is observed.
“×”: Remarkable choking is observed.

(10) Weather resistance improvement evaluation <Clear>
“◎”: In the weather resistance evaluation, the weather resistance of the non-added coating film is improved by three or more stages, and the water resistance is not lowered.
“◯”: In the weather resistance evaluation, the weather resistance of the non-added coating film is improved by two levels, and the water resistance is not lowered.
“Δ”: In the weather resistance evaluation, the weather resistance of the non-added coating film is improved by two levels, but the water resistance is lowered. Alternatively, the weather resistance is improved by one step.
“×”: Does not improve weather resistance.
<Enamel>
“◎”: In the weather resistance evaluation, the weather resistance of the non-added coating film is improved by three levels.
“◯”: In the weather resistance evaluation, the weather resistance of the non-added coating film is improved by two levels.
“Δ”: In the weather resistance evaluation, the weather resistance of the non-added coating film is improved by one step.
“×”: Does not improve weather resistance.

Example 1
60 parts of deionized water is charged into a flask equipped with a stirrer, a reflux condenser, a temperature controller, a dropping pump, and a nitrogen inlet tube. Subsequently, an amount corresponding to 5% by mass of the sum of the emulsions of all stages was weighed from the emulsion for the first stage polymerization (emulsion (I)) described in Table 1 and charged into the reaction vessel to react. After raising the temperature to 75 ° C. while replacing the inside of the container with nitrogen, an initiator solution in which 0.1 part of ammonium persulfate (polymerization initiator) was dissolved in 1 part of water was added to form seed particles. The temperature of the solution was measured with a thermometer, and after confirming the exothermic peak, the rest of the emulsion (I) was added dropwise at an internal temperature of 75 ° C. over 4 hours. After aging for 1 hour, 25% by mass aqueous ammonia was adjusted to pH 4. The emulsion (II) is added dropwise at an internal temperature of 75 ° C. over 4 hours. After dropping, the remaining monomer was reduced by aging for 2 hours while maintaining the internal temperature at 75 ° C. to form copolymer particles (α).
Thereafter, cooling was performed, and 25 mass% aqueous ammonia was added at a temperature of 60 ° C or lower until pH 9 was reached, and an appropriate amount of deionized water was added so that the solid content (NV) was 50%, thereby obtaining an aqueous resin. The solid content (NV), pH, viscosity, MFT, glass transition temperature (Tg), and weight average molecular weight (Mw) of the obtained aqueous resin of the present invention were as shown in Table 1.
In addition, the viscosity used the value measured by the Toki Sangyo Co., Ltd. product "R-100 type | mold viscosity meter", setting the temperature of aqueous resin to 25 degreeC. As the average particle size, a value obtained by measuring a sample adjusted to a concentration of 1% at 25 ° C. using a concentrated analyzer “FPAR-1000” manufactured by Otsuka Electronics Co., Ltd. was used.

(Examples 2-6, 8-10)
In the same manner as in Example 1, aqueous resins having the compositions shown in Tables 1 and 2 were prepared. The solid content (NV), pH, viscosity, MFT, glass transition temperature (Tg), and weight average molecular weight (Mw) of the obtained aqueous resin of the present invention were as shown in Tables 1 and 2.

(Example 7)
60 parts of deionized water is charged into a flask equipped with a stirrer, a reflux condenser, a temperature controller, a dropping pump, and a nitrogen inlet tube. Subsequently, an amount corresponding to 5% by mass of the total emulsion was added from the emulsion (I), charged into the reaction vessel, and heated to 60 ° C. while replacing the inside of the reaction vessel with nitrogen. After that, 0.2 part of perbutyl H-69 (manufactured by NOF Corporation) was added, followed by 0.02 part of formaldehyde sulfoxylate, 0.001 part of ferrous sulfate and 0.002 part of ethylenediaminetetraacetate. A reducing agent aqueous solution dissolved in water was added to form seed particles. After the temperature of the solution was measured with a thermometer and an exothermic peak was confirmed, an aqueous reducing agent solution in which 0.15 parts of the remaining emulsion (I) and 0.15 parts of formaldehyde sulfoxylate were dissolved in 3 parts of water was added at an internal temperature of 65 ° C. The solution was added dropwise over 4 hours, and after aging for 1 hour, 25% by weight aqueous ammonia was added until the pH reached 4, and an aqueous reducing agent solution prepared by dissolving 0.15 part of the emulsion (II) and formaldehyde sulfoxylate in 3 parts of water. Is dropped at an internal temperature of 65 ° C. over 4 hours. Further, the mixture was aged for 2 hours while keeping the internal temperature at 65 ° C. to form copolymer particles (α).
Thereafter, cooling was performed, and 25% by mass of ammonia water was added at a temperature of 60 ° C. or lower until PH9 was reached, and an appropriate amount of deionized water was added so that the solid content was 50% to obtain an aqueous resin. Table 1 shows the solid content (NV), PH, viscosity, MFT, glass transition temperature (Tg), and weight average molecular weight (Mw) of the obtained water-based resin of the present invention.

(Comparative Example 1)
An aqueous resin having the composition shown in Table 3 was prepared in the same manner as in Example 1. The solid content (NV), pH, viscosity, MFT, glass transition temperature (Tg), and weight average molecular weight (Mw) of the obtained aqueous resin were as shown in Table 3.
(Comparative Examples 2 to 11)
In the same manner as in Example 1, aqueous resins having the compositions shown in Tables 3 and 4 were prepared. The solid content (NV), pH, viscosity, MFT, glass transition temperature (Tg), and weight average molecular weight (Mw) of the obtained water-based resin were as shown in Tables 3 and 4.

(Production Example 1)
In a reactor equipped with a stirrer, a reflux condenser, a temperature controller, a dropping pump, and a nitrogen introduction tube, 45 parts of deionized water and 5% by mass of the emulsion (I) blended in the proportions shown in Table 1 are contained in the reaction vessel. The reactor was heated to 75 ° C. while replacing the inside of the reaction vessel with nitrogen, and then an initiator solution in which 0.2 part of ammonium persulfate (polymerization initiator) was dissolved in 1 part of water was added to form seed particles. After measuring the temperature of the solution with a thermometer and confirming the exothermic peak, the rest of the emulsion (I) is added dropwise over 4 hours at an internal temperature of 75 ° C., and further aged for 2 hours while maintaining the internal temperature at 75 ° C. The monomer of the emulsion (I) was polymerized to form copolymer particles (α).
Thereafter, cooling was performed, and 25 mass% ammonia water was added at a temperature of 60 ° C. or lower until pH = 9 to obtain an aqueous resin. Table 5 shows the solid content (NV), pH, viscosity, MFT, glass transition temperature (Tg), and weight average molecular weight (Mw) of the obtained aqueous resin of the present invention.
(Production Examples 2 to 4)
Emulsion (I) having the composition shown in Table 5 was prepared in the same manner as in Production Example 1, and an aqueous resin was obtained in the same manner. The solid content (NV), pH, viscosity, MFT, glass transition temperature (Tg), and weight average molecular weight (Mw) of the obtained aqueous resin were as shown in Table 5.

(Production Example 5)
A composition comprising 95 parts of octamethylcyclotetrasiloxane, 5 parts of γ-methacryloxypropyltrimethoxysilane, 310 parts of water and 0.7 part of sodium dodecylbenzenesulfonate was premixed with a homomixer, and then a pressure homogenizer was used. A silicone raw material emulsion was obtained by forced emulsification at a pressure of 200 kg / cm 2.
Next, 50 parts of water and 5 parts of dodecylbenzenesulfonic acid were charged into a flask equipped with a stirrer, a condenser, a heating jacket and a dropping pump, and the silicone was stirred for 5 hours while maintaining the temperature in the flask at 85 ° C. The raw material emulsion was added dropwise. After completion of the dropping, the polymerization was further allowed to proceed for 1 hour, followed by cooling and adding aqueous ammonia to neutralize to pH = 7 to obtain an aqueous dispersion of a polyorganosiloxane polymer. This solid content was 20%.
In a flask equipped with a stirrer, a condenser, a temperature controller, a dropping pump, and a nitrogen introduction tube, 5 parts of the obtained aqueous dispersion of polyorganosiloxane polymer in terms of solid content, and the monomers (shown in Table 2) Add 12 parts of n-BMA, 17 parts of BA and 17 parts of 2-EHA in a) and stir in a nitrogen atmosphere for 40 minutes. Thereafter, the temperature in the tank was raised to 60 ° C., 0.1 part of perbutyl H69 (69% aqueous solution of t-butyl hydroperoxide, manufactured by NOF Corporation), then 0.0002 part of ferrous sulfate, 2 ethylenediaminetetraacetic acid 2 Polymerization was initiated by adding 0.0004 part of a sodium salt and 1 part of water in which 0.02 part of Rongalite was dissolved. 1 hour after the start, the temperature in the tank was raised to 80 ° C., and after further reacting for 2 hours, an emulsified dispersion obtained by mixing the remainder of the monomer (a) shown in Table 1, an emulsifier and 10 parts of water, Then, an aqueous solution of ammonium persulfate corresponding to 0.001% by mass with respect to the monomer (a) and 10 parts of water was dropped over 2 hours. Thereafter, the mixture was kept at 80 ° C. for 60 minutes, cooled to room temperature, added with a neutralizing base shown in Table 2 to adjust pH to 9, and a heterophasic structure type polymer was obtained. The solid content (NV), pH, viscosity, and MFT of the obtained aqueous resin were as shown in Table 5 below.

In addition, the abbreviation in a table | surface has shown the following compounds.
MMA: methyl methacrylate St: styrene t-BMA: tertiary butyl methacrylate CHMA: cyclohexyl methacrylate n-BMA: normal butyl methacrylate n-BA: normal butyl acrylate 2-EHA: 2-ethylhexyl acrylate 2-HEMA: 2-hydroxyethyl methacrylate EDMA: ethylene glycol dimethacrylate AA: acrylic acid MAA: methacrylic acid ADEKA rear soap SR-10: reactive anionic surfactant (trade name, manufactured by Asahi Denka Co., Ltd.)
ADEKA rear soap ER-30: reactive nonionic surfactant (trade name, manufactured by Asahi Denka Co., Ltd.)
Latemul E-118B: non-reactive anionic surfactant (trade name, manufactured by Kao Corporation)
NDM: Normal dodecyl mercaptan

(Example 11)
10 g of the aqueous resin of Example 1 and 90 g of the aqueous coating material of Production Example 4 are collected in a glass bottle that can be tightly sealed, stirred thoroughly for 5 minutes with a glass rod, sealed tightly, and left overnight to prepare a base resin for weather resistance evaluation. did. The clear paint was prepared by the method described in the preparation of the clear paint and the enamel paint was prepared by the method described in the preparation of the enamel paint. A test plate was prepared by the method described in the preparation of the above clear test plate and the preparation of enamel test plate and used for weather resistance. In addition, a test plate was prepared by the method described in the items of water resistance and compatibility test and subjected to water resistance and compatibility test. The results of weather resistance, water resistance, weather resistance improvement and compatibility test are shown in Table 6.
(Examples 12 to 21)
Paints were prepared in the same manner as in Example 11 at the ratios shown in Table 6, and subjected to weather resistance, water resistance, and compatibility tests. The results of weather resistance, water resistance, weather resistance improvement and compatibility test are shown in Table 6.

(Comparative Examples 12 to 16)
Using the aqueous resins of Production Examples 1 to 5 as the base resin for weather resistance evaluation, paints were prepared in the same manner as in Example 11 and subjected to weather resistance and water resistance tests. The results of weather resistance and water resistance test are shown in Table 7.
(Comparative Examples 17-27)
Paints were prepared in the same manner as in Example 11 at the ratios shown in Table 7, and subjected to weather resistance, water resistance, and compatibility tests. The results of weather resistance, water resistance, weather resistance improvement and compatibility test are shown in Table 7.

As is clear from the results, the copolymer (aqueous resin) of this example is excellent in mechanical stability, storage stability, and polymerization stability, and when added to various water-based paints, the weather resistance is remarkably improved. I can plan. On the other hand, the copolymer (aqueous resin) of the comparative example is inferior in polymerization stability and storage stability, and even when these properties are practically sufficient, when added to an aqueous coating, The performance improvement function is not sufficient.
Therefore, according to the present invention, it can be seen that a weather resistance improving material for water-based paints and a highly weather-resistant water-based paint having good polymerization stability, mechanical stability and storage stability and having a remarkable weather resistance improving function can be provided.

Claims (4)

An aqueous dispersion of copolymer particles (α) obtained by multistage emulsion polymerization of an ethylenically unsaturated monomer, which is a weather resistance improver for water-based paints that satisfies the following conditions (1) to (5).
(1) An ethylenically unsaturated monomer having a piperidyl group in the molecule, wherein the ethylenically unsaturated monomer mixture (A) polymerized at the final stage in the multi-stage emulsion polymerization is represented by the following general formula (I) From (a) 5 to 60% by mass and ethylenically unsaturated monomer other than the monomer (a) (b) 40 to 95% by mass (provided the total of (a) and (b) is 100% by mass) To become a.
(2) The ethylenically unsaturated monomer mixture (B) containing the carboxyl group-containing ethylenic monomer (c) is polymerized at any stage before the final stage.
(3) The content of the ethylenically unsaturated monomer mixture (A) in the total ethylenically unsaturated monomers used for the copolymer particles (α) is 10 to 90% by mass (however, the copolymer particles (The sum of all ethylenically unsaturated monomers used in (α) is 100% by mass).
(4) The content of the ethylenically unsaturated monomer (a) in the total ethylenically unsaturated monomer used for the copolymer particles (α) is 4.5 to 50% by mass (however, the copolymer The total of all ethylenically unsaturated monomers used in the particles (α) is 100% by mass).
(5) When the ethylenically unsaturated monomer mixture (A) is 100 parts by mass, the final polymerization is performed in the presence of 0.1 to 10 parts by mass of the chain transfer agent.

(R1 represents a hydrogen atom or an alkyl group having 1 to 2 carbon atoms, X represents an oxygen atom or imino group, Y represents a hydrogen atom or an alkyl group or alkoxyl group having 1 to 20 carbon atoms, and Z represents a hydrogen atom or a cyano group. )   2. The weather resistance improver for water-based paints according to claim 1, comprising a reactive emulsifier having an unsaturated double bond capable of radical polymerization in the molecule as an emulsifier used in multistage emulsion polymerization.   2. The weather resistance improver for water-based paints according to claim 1, wherein a reactive emulsifier having an unsaturated double bond capable of radical polymerization in the molecule is used as an emulsifier used in multi-stage emulsion polymerization.   An aqueous paint comprising the weather resistance improving material for an aqueous paint according to claim 1, 2 or 3.