JP2002234917A - Aqueous weather-resistant resin emulsion and its production method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an aqueous resin emulsion which, even when a light stabilizer for forming a coating film excellent in weather resistance is added, is excellent in polymerization stability and, when formed into a coating film, exhibits excellent weather resistance, and its production method. SOLUTION: This aqueous resin emulsion is obtained by the emulsion polymerization of at least one free-radically polymerizable monomer and 1,2,2,6,6- pentamethyl-4-piperidinyl methacrylate in an aqueous medium. A method for producing the emulsion is also provided.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an aqueous emulsion of a resin having good polymerization stability and providing a film having excellent weather resistance and a method for producing the same.

[0002]

2. Description of the Related Art Resins obtained by emulsion polymerization, among which acrylic resin emulsions, are often used as resins for water-based paints in the form of films formed by drying at room temperature or under heating. In such a case, there was a problem of deterioration such as a decrease in gloss and discoloration, which was insufficient from the viewpoint of long-term weather resistance. Therefore, development of a resin emulsion to which a light stabilizer is added for the purpose of improving long-term weather resistance against deterioration due to ultraviolet light and visible light has been desired. However, when adding a light stabilizer to a resin emulsion, for example, an acrylic resin emulsion,
The emulsion state in emulsion polymerization becomes unstable, and a large amount of aggregates or gelation occurs during the polymerization, so that a stable emulsion may not be obtained.

Further, in an acrylic resin emulsion into which a light stabilizer is introduced, the weather resistance may not always be improved depending on the kind of the light stabilizer.

[0004] Further, as an emulsion for forming a weather-resistant film, a composition for an emulsion-type paint using a cycloalkyl group-containing polymerizable monomer in Japanese Patent No. 2637574, and an alkoxysilane in Japanese Patent Application Laid-Open No. 6-122732 are disclosed. Synthetic resin aqueous emulsion for durable paint using a group-containing polymerizable monomer and a cycloalkyl group-containing polymerizable monomer, a curable resin composition using a silyl group-containing polymerizable monomer in JP-A-7-157625 Japanese Patent Application Laid-Open No. H10-120724 discloses a silicone-modified high-durability emulsion and the like, but improvement in film formation and weather resistance is desired.

[0005]

SUMMARY OF THE INVENTION The present inventors have found that even when a light stabilizer component for forming a film having excellent weather resistance is introduced into an aqueous emulsion of a synthetic resin, polymerization stability is excellent, and The present inventors have intensively studied to obtain an aqueous emulsion having excellent weather resistance when formed into a film and a method for producing the same.

[0006]

As a result, one or more radically polymerizable monomers and 1,2,2,6,6-pentamethyl-4-piperidinyl methacrylate are prepared in an aqueous medium. The inventors have found that the above problems can be overcome by emulsion polymerization, and have completed the present invention. Emulsion polymerization of (1) one or more radical polymerizable monomers and 1,2,2,6,6-pentamethyl-4-piperidinyl methacrylate of the present invention in an aqueous medium In the obtained resin aqueous emulsion, preferably, in (2) and (1), the radically polymerizable monomer is (meth) methyl acrylate, (meth) ethyl acrylate, (meth) acrylic acid n
-Butyl, i-butyl (meth) acrylate, t-butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, (meth) acrylic acid, acrylonitrile, styrene, 2-hydroxyethyl (meth) acrylate Or an aqueous resin emulsion which is a compound selected from (poly) oxyethylene mono (meth) acrylate, (3)
(1) The aqueous resin emulsion according to (1), wherein the radical polymerizable monomer is a compound selected from methyl acrylate, 2-ethylhexyl methacrylate, acrylic acid, and polyoxyethylene monomethacrylate.
In any one of (1) to (3), a resin aqueous emulsion obtained by emulsion polymerization at a pH of from 6 to 10;
(6) In any one of (1) to (5), an aqueous resin emulsion obtained by emulsion polymerization at a pH of 6.5 to 9, wherein 1,2,2,6,
The resin aqueous emulsion wherein the amount of 6-pentamethyl-4-piperidinyl methacrylate is 0.1 to 200 parts by weight, (7) any one of (1) to (5),
1,2,2,6,6-pentamethyl for radically polymerizable monomers
The amount of -4-piperidinyl methacrylate is 0.5 to 1
0 part by weight of a resin aqueous emulsion, which is (8) one or more radically polymerizable monomers and 1,2,2,6,6-pentamethyl-4-piperidinyl methacrylate of the present invention. In a method for producing a resin aqueous emulsion obtained by emulsion polymerization in an aqueous medium, preferably, in (9) and (8), the radical polymerizable monomer is
Methyl (meth) acrylate, ethyl (meth) acrylate, n-butyl (meth) acrylate, i-butyl (meth) acrylate, t-butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, (10) (8) A method for producing a resin aqueous emulsion which is a compound selected from (meth) acrylic acid, acrylonitrile, styrene, 2-hydroxyethyl (meth) acrylate or (poly) oxyethylene mono (meth) acrylate. Wherein the radical polymerizable monomer is a compound selected from methyl acrylate, 2-ethylhexyl methacrylate, acrylic acid, and polyoxyethylene monomethacrylate; (1
0) The method for producing a resin aqueous emulsion obtained by emulsion polymerization at a pH of 6 to 10 in any one of (12), (8) to (10). (13) In the method for producing a resin aqueous emulsion obtained by emulsion polymerization, in any one of (13), (8) to (12), 1,2,2,6,6-pentamethyl- In the method for producing a resin aqueous emulsion in which the amount of 4-piperidinyl methacrylate is 0.1 to 200 parts by weight, the radical polymerizable monomer according to any one of (14), (8) to (12), And a method for producing an aqueous resin emulsion in which the amount of 1,2,2,6,6-pentamethyl-4-piperidinyl methacrylate is 0.5 to 10 parts by weight based on the weight of the resin emulsion.

Hereinafter, the present invention will be described in detail.

The radically polymerizable monomer used in the present invention is not particularly limited as long as it is generally used for emulsion polymerization. For example, methyl (meth) acrylate, ethyl (meth) acrylate, (meth) acrylic N-butyl acid, iso-butyl (meth) acrylate, t-methacrylate
-Butyl, 2-ethylhexyl (meth) acrylate,
Esters of acrylic acid or methacrylic acid such as dodecyl (meth) acrylate and cycloalkyl (meth) acrylate; hydroxy such as 2-hydroxyethyl (meth) acrylate and 2-hydroxypropyl (meth) acrylate (Meth) acrylates having a group; diethylene glycol (meth) acrylate, diethylene glycol methoxy (meth) acrylate, (meth)
(Poly) oxyethylene mono (meth) acrylates having 1 to 100 ethylene oxide groups such as tetraethylene glycol acrylate, tetraethylene glycol methoxy (meth) acrylate; acrylic acid, methacrylic acid, itaconic acid, Α, β-unsaturated carboxylic acids such as maleic acid and fumaric acid; vinyl cyanides such as (meth) acrylonitrile; α, β-unsaturated amides such as acrylamide; and styrene. .

These radically polymerizable monomers may be used singly or as a mixture of two or more kinds in an arbitrary ratio.

Among these radically polymerizable monomers, esters of acrylic acid or methacrylic acid, α, β-unsaturated carboxylic acids, (meth) acrylic esters having a hydroxy group or (poly) ) Oxyethylene mono (meth) acrylates, and more preferably, methyl (meth) acrylate, ethyl (meth) acrylate, n-butyl (meth) acrylate, i-butyl (meth) acrylate, T-butyl (meth) acrylate,
2-ethylhexyl (meth) acrylate, (meth) acrylic acid, acrylonitrile, styrene, 2-hydroxyethyl (meth) acrylate or (poly) oxyethylene mono (meth) acrylate, particularly preferably,
Examples include methyl acrylate, acrylic acid, 2-ethylhexyl methacrylate, and polyoxyethylene monomethacrylate.

These radical polymerizable monomers can be easily obtained from reagent manufacturers such as Wako Pure Chemical Industries, Ltd. 1,2,2,6,6-pentamethyl-4-piperidinyl methacrylate used as a radical polymerizable light stabilizer in the present invention is described in, for example, JP-A-11-1400.
No. 49, it can be produced. 1,
The amount of 2,2,6,6-pentamethyl-4-piperidinyl methacrylate used is preferably 0.1 part by weight, based on 100 parts by weight of one or more radical polymerizable monomers. To 200 parts by weight, more preferably 0.5 to 10 parts by weight, based on 100 parts by weight of one or more radical polymerizable monomers.

The aqueous medium used in the present invention means any one of: i) water; ii) a medium containing 50% by weight or more of water and containing a water-soluble organic solvent such as ethanol or dimethylacetamide as another component. . When producing the aqueous resin emulsion in the present invention, in order to ensure stability during production,
It is necessary to maintain the pH of the emulsion polymerization solution at the time of emulsion polymerization at 6 or more. A preferable pH of the emulsion polymerization solution is 6 to 10, and a more preferable pH of the emulsion polymerization solution is 6.5 to 9. is there. In particular, when emulsion polymerization is carried out at a pH of the emulsion polymerization solution of 6 or less, the emulsified state during the polymerization becomes unstable, the emulsion polymerization becomes difficult, a large amount of aggregates are generated or the gelation occurs during the polymerization, and the stable emulsion is formed. Can not get. The pH of the emulsion polymerization solution is adjusted to 6 or more by adding a basic compound. Examples of such basic compounds include alkali metal compounds such as sodium hydroxide and potassium hydroxide; ammonia; monomethylamine, diethylamine, triethylamine, monopropylamine, dimethylpropylamine, monoethanolamine,
Water-soluble organic amines such as diethanolamine, triethanolamine, ethylenediamine, diethylenetriamine, dimethylaminoethanol, and methylethanolamine are exemplified. Of these basic compounds, ammonia is preferred. As the basic compound, only one kind may be used, or two or more kinds may be used in combination.

An ultraviolet absorber can be added to the aqueous resin emulsion of the present invention, if necessary. Examples of such an ultraviolet absorber include a radically polymerizable benzophenone-based ultraviolet absorber, an additive benzophenone-based ultraviolet absorber, and a benzotriazole-based ultraviolet absorber. Examples of the radical polymerizable benzophenone-based ultraviolet absorber and the added benzophenone-based ultraviolet absorber include, for example, 2,4-dihydroxybenzophenone, 2-hydroxy-4-methoxybenzophenone, 2-hydroxy-4-stearyloxybenzophenone, and 2-hydroxy- 4-methacryloxybenzophenone and 2-hydroxy-5-methacryloxybenzophenone (all manufactured by Sumitomo Chemical Co., Ltd.). Examples of the benzotriazole-based ultraviolet absorber include 2- (2'-hydroxy-5'-methylphenyl) benzotriazole (manufactured by Sumitomo Chemical Co., Ltd.) and 2- (2'-hydroxy-
5'-t-butylphenyl) benzotriazole, 2- (3-dodecyl-5-methyl-2-hydroxyphenyl) benzotriazole (all manufactured by Ciba Specialty Co., Ltd.), 2- [2-
Hydroxy-3,5-bis (α, α-dimethylbenzyl) phenyl] -2H-benzotriazole (Sanol UV-90, manufactured by Sankyo Co., Ltd.), 2- (2′-hydroxy-5′-methacryloxyethylphenyl) ) -2H-benzotriazole (RUVA-93, manufactured by Otsuka Chemical Co., Ltd.), 2- (2'-hydroxy-5-methacryloxyethyl-3-t-butylphenyl) -2H-benzotriazole (Otsuka Chemical Co., Ltd. )). The amount used when the ultraviolet absorber is added is preferably up to 10 parts by weight with respect to 100 parts by weight of one or more radical polymerizable monomers, and more preferably one or more types. It is at most 5 parts by weight based on 100 parts by weight of the radical polymerizable monomer. Further, a light stabilizer can be added to the aqueous resin emulsion of the present invention, if necessary.

Examples of such a light stabilizer include bis (2,2,6,6-tetramethyl-4-piperidyl) sebacate (trade name: SANOL LS-770, manufactured by Sankyo Co., Ltd.), bis (1 , 2,2,6,6-pentamethyl-4-piperidyl) sebacate (trade name: SANOL LS-292, manufactured by Sankyo Co., Ltd.), 1- [2-
[3- (3,5-di-t-butyl-4-hydroxyphenyl) propionyloxy] ethyl] -4- [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionyloxy]- 2,2,6,6-tetramethylpiperidine (trade name: SANOL LS-2626, a product of Sankyo Co., Ltd.), 4-benzoyloxy-2,2,6,6-tetramethylpiperidine (trade name: SANOL LS) -744, Sankyo Co., Ltd.
Product), 8-acetyl-3-dodecyl-7,7,9,9-tetramethyl
Addition-type hindered amine light stabilizers such as -1,3,8-triazaspiro [4.5] -2,4-dione (trade name: SANOL LS-440, manufactured by Sankyo Co., Ltd.).

The amount of the light stabilizer to be added is preferably up to 10 parts by weight, more preferably one or more than one part by weight, per 100 parts by weight of one or more radically polymerizable monomers. It is at most 5 parts by weight based on 100 parts by weight of at least one kind of radical polymerizable monomer.

In the present invention, examples of the emulsifier for emulsion polymerization include an anionic surfactant and a reactive surfactant. Examples of the anionic surfactant include Newcol-560SF and Ne.
polyoxyethylene nonylphenyl ether sulfate salts such as wcol-562SF (all manufactured by Nippon Emulsifier Co., Ltd.); Newcol-707SF, Newcol-7
07SN, Newcol-714SF, Newcol-7
Polyoxyethylene (mono, di, tri) styrenated phenyl ether sulfates such as 23SF and Newcol-740SF (all manufactured by Nippon Emulsifier Co., Ltd.); Ne
wcol-2308SF, Newcol-2320SN,
Newcol-1305SN (The above is Nippon Emulsifier Co., Ltd.)
Newcol-271A, Newcol-27
Long-chain alkyl diphenyl ether disulfonic acid salt such as 1NH (all manufactured by Nippon Emulsifier Co., Ltd.): Newcol-
Long-chain alkylbenzene sulfonates such as 210, Newcol-220 (all manufactured by Nippon Emulsifier Co., Ltd.);
Or Newcol-RA-331, Newcol-RA-3
Long-chain alkyl sulfates such as 32 (all manufactured by Nippon Emulsifier Co., Ltd.).

As the above-mentioned reactive surfactant, for example, A
ntox-MS-2N or Antox-MS-60 (or more,
Japan Emulsifier Co., Ltd.). Among the above emulsifiers, polyoxyethylene (mono, di, tri) styrenated phenyl ether sulfate (preferably ammonium salt and sodium salt, which is preferably an anionic surfactant, particularly preferably Ammonium salt) or a reactive surfactant.

These emulsifiers may be used alone or as a mixture of two or more. The amount of the emulsifier is not particularly limited, but is preferably 0.1 to 1 part by weight based on 100 parts by weight of one or more radical polymerizable monomers.
0 parts by weight, more preferably 1 part by weight to 5 parts by weight based on 100 parts by weight of one or more radical polymerizable monomers.

In the present invention, examples of the polymerization initiator for emulsion polymerization include an azo initiator, a persulfate initiator, and a peroxide initiator.

Examples of the azo initiator include, for example, 2,2′-azobisisobutyronitrile, 4.4′-azobis (4-cyanovaleric acid), 2.2′-azobis [2-methyl-N- (2-hydroxy Ethyl) propionamide] and 2.2'-azobis (2-amidinopropane) dihydrochloride (all manufactured by Wako Pure Chemical Industries, Ltd.).

Examples of the persulfate-based initiator include, for example, ammonium persulfate, potassium persulfate, and sodium persulfate (all manufactured by Mitsubishi Gas Chemical Co., Ltd.).

Examples of the peroxide-based initiator include hydrogen peroxide, benzoyl peroxide, and di-t-butyl peroxide (all manufactured by NOF Corporation).

Among these polymerization initiators, preferred are polymerization initiators which do not leave a sulfate group, such as azo-based initiators and peroxide-based initiators. More preferred are 2.2'-azobis [2 -
Methyl-N- (2-hydroxyethyl) propionamide
Or azo-based polymerization initiators such as 2,2'-azobis (2-amidinopropane) dihydrochloride.

The amount of the polymerization initiator is preferably 0.05 to 1 part by weight based on 100 parts by weight of one or more radical polymerizable monomers. The production of the aqueous resin emulsion of the present invention can be carried out by using a known emulsion polymerization means such as a batch polymerization method, a monomer drop polymerization method, and an emulsion monomer drop polymerization method.

The reaction conditions in the present invention may be set according to the composition of the radically polymerizable monomer and the like, and are not particularly limited, but include, for example, the following conditions.

The reaction temperature is preferably in the range of a polymerization temperature of 65 ° C. to 90 ° C. under normal pressure, and is preferably 80 ° C. to 9 ° C.
More preferably, it is within the range of the polymerization temperature of 0 ° C.
The reaction time varies depending on the reaction temperature and the like, but is preferably in the range of 1 hour to 10 hours, and preferably 3 hours to 8 hours.
It is particularly preferred to be within the time range.

The emulsion polymerization is preferably carried out in an atmosphere of an inert gas such as nitrogen gas.

When acceleration of the polymerization rate and polymerization at 70 ° C. or lower at a low temperature are desired, a reducing agent such as sodium bisulfite, ferrous chloride, ascorbate, or Rongalite is combined with a radical polymerization catalyst. It is advantageous to use them. Furthermore, in order to adjust the molecular weight,
It is also possible to optionally add a chain transfer agent such as dodecyl mercaptan. Furthermore, additives well known in the emulsion polymerization technique, for example, chelating agents, buffers, salts of organic acids, solvents and the like can be used. The aqueous resin emulsion obtained by the above production method can be used as a coating material or as a coating agent for various resins or woodwork. In addition, the resin aqueous emulsion of the present invention contains components usually blended in water-based paints, such as pigments, fillers, toners, wetting agents, film-forming assistants, thickeners, plasticizers, and defoamers. , A pigment dispersant, a dye, a preservative and the like can be arbitrarily compounded.

[0029]

The present invention will be described in more detail with reference to the following Examples, Comparative Examples and Test Examples, which by no means limit the present invention. In the examples and comparative examples, “parts” indicates “parts by weight”. Example 1 40 parts of 2-ethylhexyl acrylate, 60 parts of methyl methacrylate, 2 parts of acrylic acid and 1,2,2,
6,6-pentamethyl-4-piperidinyl methacrylate 1
Part of the mixed solution and 10.3 parts of 10% 2,2 'of Newcol 707SF (30% aqueous product manufactured by Nippon Emulsifier Co., Ltd.)
-Azobis (2-amidinopropane) dihydrochloride aqueous solution 5.2
163.2 parts of a monomer aqueous dispersion having a pH of 8.5, comprising 42.6 parts of water, 42.6 parts of water and 2.1 parts of 28% aqueous ammonia.

Next, 50 parts of ion-exchanged water and 8.2 parts of the above monomer aqueous dispersion were charged into a glass reactor equipped with a reflux condenser, a thermometer, a nitrogen gas inlet, a dropping funnel and a stirrer. Then, the temperature of the reaction vessel was kept at 80 ° C. in a nitrogen stream for 30 minutes to carry out pre-polymerization.

In this reaction vessel, a monomer aqueous dispersion 155.
Five parts were dropped at the same temperature over 3 hours to carry out polymerization. After completion of the dropwise addition, the emulsion polymerization was completed while stirring at the same temperature for 3 hours, followed by cooling and filtration through a 100-mesh nylon cloth to obtain an aqueous resin emulsion of the present invention. [Example 2] 40 parts of 2-ethylhexyl acrylate, 60 parts of methyl methacrylate, 2 parts of acrylic acid and 1,2,2,
6,6-pentamethyl-4-piperidinyl methacrylate 3
Part of the mixed solution and 10.3 parts of Newcol 714SF (manufactured by Nippon Emulsifier Co., Ltd., 30% aqueous solution), 5.2 parts of 10% aqueous ammonium persulfate, 44.4 parts and 28 parts
166.8 parts of a monomer aqueous dispersion having a pH of 8.5 and consisting of 1.9 parts of aqueous ammonia were prepared.

Next, 100 parts of ion-exchanged water and 8.4 parts of the above monomer aqueous dispersion were placed in a 500 ml glass reaction vessel equipped with a reflux condenser, a thermometer, a nitrogen gas inlet, a dropping funnel and a stirrer. The pre-polymerization was carried out while keeping the temperature of the reaction vessel at 80 ° C. for 30 minutes in a charged nitrogen atmosphere.

In this reaction vessel, a monomer aqueous dispersion 158.
Eight parts were dropped at the same temperature over 3 hours to carry out polymerization. After completion of the dropwise addition, the emulsion polymerization was completed while stirring at the same temperature for 3 hours, followed by cooling and filtration through a 100-mesh nylon cloth to obtain an aqueous resin emulsion of the present invention. Example 3 40 parts of 2-ethylhexyl acrylate, 60 parts of methyl methacrylate, 2 parts of acrylic acid, 1,2,2,6,
6-pentamethyl-4-piperidinyl methacrylate
5 parts and 0.5 part of 2- (2'-hydroxy-5'-methylacryloyloxyethylphenyl) -2H-benzotriazole (trade name: RUVA-93, a radical polymerizable ultraviolet absorber manufactured by Otsuka Chemical Co., Ltd.) Mixed solution and New
col 714SF (manufactured by Japan Emulsifier Co., Ltd., 30% aqueous solution product) 10.3 parts, 10% ammonium persulfate aqueous solution 5.2 parts, water 42.6 parts and 28% ammonia water 2.
81.9 pH 8.5 monomer aqueous dispersion 161.9
Parts were prepared.

Next, 50 parts of ion-exchanged water and 8.2 parts of the above monomer aqueous dispersion were charged into a glass reactor equipped with a reflux condenser, a thermometer, a nitrogen gas inlet, a dropping funnel and a stirrer. Then, the temperature of the reaction vessel was kept at 80 ° C. in a nitrogen stream for 30 minutes to carry out pre-polymerization.

The monomer aqueous dispersion 155.
Seven parts were dropped at the same temperature over 3 hours to carry out polymerization. After completion of the dropwise addition, the emulsion polymerization was completed while stirring at the same temperature for 3 hours, followed by cooling and filtration through a 100-mesh nylon cloth to obtain an aqueous resin emulsion of the present invention. Example 4 The amount of 1,2,2,6,6-pentamethyl-4-piperidinyl methacrylate was added to 0.5 part of 2- [2-hydroxy-
3,5-bis (α, α-dimethylbenzyl) phenyl] -2H-benzotriazole (trade name: SANOL UV-90 Sankyo Co., Ltd.)
The polymerization was carried out in the same manner as in Example 1 except that the amount of the additive-type ultraviolet absorber was changed to 0.5 part, and the amount of the 28% aqueous ammonia was changed to 2.3 parts. An aqueous resin emulsion was obtained. Example 5 35 parts of 2-ethylhexyl acrylate, 55 parts of methyl methacrylate, MA-100 (manufactured by Nippon Emulsifier Co., Ltd., polyoxyethylene monomethacrylate) 1
0 parts, acrylic acid 2 parts and 1,2,2,6,6-pentamethyl-4-
A mixture of 1 part of piperidinyl methacrylate and Newc
ol 707SF (manufactured by Nippon Emulsifier Co., Ltd., 30% aqueous solution product) 10.3 parts, 10% 2,2'-azobis (2-amidinopropane) .2 hydrochloride aqueous solution 5.2 parts, water 42.6 parts and 163.3 parts of a monomer aqueous dispersion having a pH of 8.5 and comprising 2.2 parts of 28% aqueous ammonia were prepared.

Next, 50 parts of ion-exchanged water and 8.2 parts of the above monomer aqueous dispersion were charged into a glass reactor equipped with a reflux condenser, a thermometer, a nitrogen gas inlet, a dropping funnel and a stirrer. Then, the temperature of the reaction vessel was kept at 80 ° C. in a nitrogen stream for 30 minutes to carry out pre-polymerization.

The monomer aqueous dispersion 155.
One part was dropped at the same temperature over 3 hours to carry out polymerization. After completion of the dropwise addition, the emulsion polymerization was completed while stirring at the same temperature for 3 hours, followed by cooling and filtration through a 100-mesh nylon cloth to obtain an aqueous resin emulsion of the present invention. [Example 6] Polymerization was carried out in the same manner as in Example 1, except that the amount of 28% aqueous ammonia was changed to 1.9 parts and the polymerization initiator was changed to 5.2 parts of a 10% aqueous solution of ammonium persulfate. An aqueous resin emulsion of the present invention was obtained. Example 7 19 parts of 2-ethylhexyl acrylate, 29 parts of methyl methacrylate, 2 parts of acrylic acid, and 1,2,2,
6,6-pentamethyl-4-piperidinyl methacrylate 5
0 parts of the mixed solution and 10 parts of Newcol 707SF (a 30% aqueous solution product of Nippon Emulsifier Co., Ltd.), 10 parts of an aqueous 2,2′-azobis (2-amidinopropane) .2 hydrochloride solution, 5 parts of water, 38 parts of water and PH consisting of 2.1 parts of 28% aqueous ammonia
155.1 parts of an aqueous monomer dispersion of 8.5 were prepared. Next, ion-exchanged water was placed in a glass reaction vessel equipped with a reflux condenser, a thermometer, a nitrogen gas inlet, a dropping funnel and a stirrer.
And 7.8 parts of the above monomer aqueous dispersion, and the prepolymerization was carried out by keeping the temperature of the reaction vessel at 80 ° C. for 30 minutes in a nitrogen stream.

In this reaction vessel, the monomer aqueous dispersion 147.
Three parts were dropped at the same temperature over 3 hours to carry out polymerization. After completion of the dropwise addition, the emulsion polymerization was completed while stirring at the same temperature for 3 hours, followed by cooling and filtration through a 100-mesh nylon cloth to obtain an aqueous resin emulsion of the present invention.

4 parts (light) of 100 parts of the obtained resin emulsion per 100 parts of a commercially available acrylic resin emulsion containing no light stabilizer (trade name: Boncoat EC-819, manufactured by Dainippon Ink and Chemicals, Inc.) 1 part) was added as a stabilizer concentration, and evaluation was performed in the same manner as in Example 1. Example 8 40 parts of 2-ethylhexyl acrylate, 60 parts of methyl methacrylate, 2 parts of acrylic acid, 1,2,2,6,6-
A liquid mixture of 1 part of pentamethyl-4-piperidinyl methacrylate (development code name: C10-3410, manufactured by Sankyo Co., Ltd., radical polymerizable light stabilizer) and Newcol 707
SF (manufactured by Japan Emulsifier Co., Ltd., 30% aqueous solution product) 10.
3 parts, 10% 2,2′-azobis [2- (N-2-carboxyethylamidino) propane] .hydrate aqueous solution 5.2 parts, water 42.
163.2 parts of an aqueous monomer dispersion having a hydrogen ion concentration (pH) of 8.5 consisting of 6 parts and 2.1 parts of 28% aqueous ammonia were prepared.

Next, 50 parts of ion-exchanged water and 8.2 parts of the above monomer aqueous dispersion were charged into a glass reactor equipped with a reflux condenser, a thermometer, a nitrogen gas inlet, a dropping funnel and a stirrer. Then, the temperature of the reaction vessel was kept at 80 ° C. in a nitrogen stream for 30 minutes to carry out pre-polymerization.

In this reaction vessel, the monomer aqueous dispersion 155.
Five parts were dropped at the same temperature over 3 hours to carry out polymerization. After completion of the dropwise addition, the emulsion polymerization was completed while stirring at the same temperature for 3 hours, followed by cooling and filtration through a 100-mesh nylon cloth to obtain an aqueous resin emulsion of the present invention. Comparative Example 1 40 parts of 2-ethylhexyl acrylate, 60 parts of methyl methacrylate, 2 parts of acrylic acid and 1,2,2,
6,6-pentamethyl-4-piperidinyl methacrylate 1
Part of the mixed solution and 10.3 parts of Newcol 707SF (manufactured by Nippon Emulsifier Co., Ltd., 30% aqueous solution), 5.2 parts of 10% ammonium persulfate aqueous solution, 42.6 parts of water and 2 parts
161.2 parts of an aqueous monomer dispersion of pH 4 consisting of 0.1 part of 8% aqueous ammonia was prepared.

Next, 50 parts of ion-exchanged water and 8.1 parts of the above monomer aqueous dispersion were charged into a glass reactor equipped with a reflux condenser, a thermometer, a nitrogen gas inlet, a dropping funnel and a stirrer. When the temperature of the reaction vessel was kept at 80 ° C. in a stream of nitrogen for 30 minutes and pre-polymerization was carried out, the whole gelled, and a stable polymer emulsion could not be obtained. Comparative Example 2 40 parts of 2-ethylhexyl acrylate, 60 parts of methyl methacrylate, 2 parts of acrylic acid, and 1,2,2,
6,6-pentamethyl-4-piperidinyl methacrylate 1
Part of the mixed solution and 10.3 parts of 10% 2,2 'of Newcol 707SF (30% aqueous product manufactured by Nippon Emulsifier Co., Ltd.)
-Azobis (2-amidinopropane) dihydrochloride aqueous solution 5.2
Of a monomer aqueous dispersion having a pH of 5 and containing 42.6 parts of water, 42.6 parts of water and 0.8 part of 28% aqueous ammonia.

Next, 50 parts of ion-exchanged water and 8.1 parts of the above monomer aqueous dispersion were charged into a glass reactor equipped with a reflux condenser, a thermometer, a nitrogen gas inlet, a dropping funnel and a stirrer. When the temperature of the reaction vessel was kept at 80 ° C. in a stream of nitrogen for 30 minutes and pre-polymerization was carried out, the whole gelled, and a stable polymer emulsion could not be obtained. Comparative Example 3 1,2,2,6,6-pentamethyl-4-piperidinyl methacrylate was replaced with bis (1,2,2,6,6-pentamethyl-4-
Example 1 except that piperidyl) sebacate (trade name: SANOL LS-292, manufactured by Sankyo Co., Ltd., added light stabilizer) and the amount of 28% aqueous ammonia was changed to 2.5 parts. Polymerization was carried out in the same manner to obtain an aqueous resin emulsion. Comparative Example 4 1,2,2,6,6-Pentamethyl-4-piperidinyl methacrylate was replaced with bis (1,2,2,6,6-pentamethyl-4-
Piperidyl) sebacate (trade name: SANOL LS-292, manufactured by Sankyo Co., Ltd., added light stabilizer), and 2-
(2'-Hydroxy-5'-methylacryloyloxyethylphenyl) -2H-benzotriazole (trade name: RUVA-93, a radical polymerizable ultraviolet absorber manufactured by Otsuka Chemical Co., Ltd.) was treated with 2- [2-hydroxy-3 , 5-Bis (α, α-dimethylbenzyl) phenyl] -2H-benzotriazole (trade name: SANOL UV-90, manufactured by Sankyo Co., Ltd., additive UV absorber) Polymerization was carried out in the same manner to obtain an aqueous resin emulsion. Comparative Example 5 Example 1 was repeated except that 1,2,2,6,6-pentamethyl-4-piperidinyl methacrylate was not used and the amount of 28% aqueous ammonia was changed to 2.7 parts. Polymerization was performed in the same manner to obtain a resin aqueous emulsion of Comparative Example. [Test Examples] The following tables show the composition ratios and test results of the aqueous resin emulsions of Examples and Comparative Examples (Table 1 shows Examples, and Table 2 shows Test Examples). The test items, test conditions, and evaluation criteria are as follows. (A) Polymerization stability: The aqueous resin emulsion after completion of emulsion polymerization was filtered through a 100-mesh screen, the remaining aggregates were dried at 110 ° C. for 5 hours, and the weight was expressed in terms of% by weight based on the monomers used. And polymerization stability. Evaluation criteria A: The emulsion polymerization is very stable when the amount of aggregate is 0.001% by weight / monomer or less. ：: Aggregate amount is larger than 0.010% by weight / monomer, and emulsion polymerization is stable. ×: A large amount of aggregates are generated and emulsion polymerization cannot be performed.
Gelation occurs in the preceding emulsion polymerization, and stable emulsion polymerization cannot be performed. (B) Hydrogen ion concentration (pH) of monomer aqueous dispersion: JI
It was measured according to SZ-8802. (C) Solids concentration: 1 g of an aqueous resin emulsion was added, 5 g of pure water was added, and after drying at 105 ° C. for 2 hours, the evaporation residue was expressed in%. (D) Viscosity: The viscosity of the aqueous resin emulsion at 25 ° C. was measured with a BL type viscometer. (E) Average particle diameter: measured by a laser diffraction particle diameter measuring method. (F) Initial gloss value: A resin aqueous emulsion was prepared using a wire coater No. 34, applied to an iron plate at 110 ° C.,
A test piece was prepared by drying for 5 minutes. 20 ° at that time
The 20 ° specular reflectance was measured as the initial gloss value (this was taken as the test start time, ie, zero time). (G) Gloss retention: Exposure test using a fluorescent Sampras-type tester (UVCON: UC-1; Toyo Seiki Seisaku-sho, Ltd.) [Cycle: 8 hours light irradiation (70 ° C)
+ Wet 4 hours (50 ° C.)]. The 20 ° -20 ° specular reflectance after 1000 hours of exposure was measured as the final gloss value, divided by the initial gloss value, and this value was calculated as the gloss retention.

[0044]

[Table 1]

[0045]

[Table 2]

The symbols in the table are as follows. MA-100: polyoxyethylene monomethacrylate (ethylene oxide added 10 mol) V-50: 2,2'-azobis (2-amidinopropane) dihydrochloride APS: ammonium persulfate.

The units of the radical polymerizable monomer, light stabilizer, ultraviolet absorber, surfactant, polymerization initiator and basic substance are parts by weight.

It was shown that the aqueous resin emulsion of the examples had better polymerization stability, gave a high gloss retention when formed into a film, and exhibited excellent weather resistance as compared with the aqueous resin emulsion of the comparative example. .

[0049]

By using the aqueous emulsion of a weatherable resin according to the present invention, the long-term weather resistance is remarkably excellent, and the gloss, retention, crack resistance, blister resistance and yellowing resistance can be sufficiently satisfied. A coating is obtained. Further, since it is an aqueous emulsion, it has excellent pigment dispersibility. Therefore, it can be dispersed in inorganic and organic pigments to obtain a colored coating by a known pigment dispersion method. Therefore, it can be used for a wide range of applications, such as construction, building materials, woodwork, automobiles, large structures, home appliances, and steel equipment.

Further, the method for producing an aqueous weatherable resin emulsion of the present invention is excellent in polymerization stability such as suppressing generation of agglomerates and gelation during production of an aqueous resin emulsion.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Hiroyuki Tomita 1-1-1, Chidoricho, Kawasaki-ku, Kawasaki-shi, Kanagawa Japan Emulsifier Co., Ltd. Kawasaki Plant Research Department (72) Inventor Hideo Takeshiba 1 Hiromachi, Shinagawa-ku, Tokyo No. 2-58 Sankyo Co., Ltd. (72) Inventor Takaaki Yamazaki 1-2-58 Hiromachi, Shinagawa-ku, Tokyo Sankyo Co., Ltd. F-term (reference) 4J011 KA04 KA06 KB05 KB29 4J100 AB02Q AJ02Q AJ08Q AJ09Q AL03Q AL04Q AL08P AL09Q AM02Q AM21Q BA03Q BA05Q BA08Q BC65P DA36 FA20 FA27 FA30 JA01

Claims (14)

[Claims] 1. An emulsion polymerization of one or more radical polymerizable monomers and 1,2,2,6,6-pentamethyl-4-piperidinyl methacrylate in an aqueous medium. Resin aqueous emulsion. 2. The method according to claim 1, wherein the radical polymerizable monomer is methyl (meth) acrylate, ethyl (meth) acrylate, n-butyl (meth) acrylate, i-butyl (meth) acrylate, From t-butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, (meth) acrylic acid, acrylonitrile, styrene, 2-hydroxyethyl (meth) acrylate or (poly) oxyethylene mono (meth) acrylate An aqueous resin emulsion which is the compound of choice. 3. The resin aqueous emulsion according to claim 1, wherein the radical polymerizable monomer is a compound selected from methyl acrylate, 2-ethylhexyl methacrylate, acrylic acid, and polyoxyethylene monomethacrylate. 4. The method according to claim 1, wherein
An aqueous resin emulsion obtained by emulsion polymerization at pH 6 to 10. 5. The method according to claim 1, wherein
An aqueous resin emulsion obtained by emulsion polymerization at pH 6.5 to 9. 6. The method according to claim 1, wherein:
1,2,2,6,6-pentamethyl for radically polymerizable monomers
-4-piperidinyl methacrylate in an amount of 0.1 to 20
0 parts by weight of an aqueous resin emulsion. 7. The method according to claim 1, wherein
1,2,2,6,6-pentamethyl for radically polymerizable monomers
The amount of -4-piperidinyl methacrylate is 0.5 to 10
Aqueous resin emulsion in parts by weight. 8. It is obtained by emulsion polymerization of one or more radical polymerizable monomers and 1,2,2,6,6-pentamethyl-4-piperidinyl methacrylate in an aqueous medium. A method for producing an aqueous resin emulsion. 9. The method according to claim 8, wherein the radical polymerizable monomer is methyl (meth) acrylate, ethyl (meth) acrylate, n-butyl (meth) acrylate, i-butyl (meth) acrylate, From t-butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, (meth) acrylic acid, acrylonitrile, styrene, 2-hydroxyethyl (meth) acrylate or (poly) oxyethylene mono (meth) acrylate A method for producing an aqueous resin emulsion, which is a selected compound. 10. The method for producing a resin aqueous emulsion according to claim 8, wherein the radical polymerizable monomer is a compound selected from methyl acrylate, 2-ethylhexyl methacrylate, acrylic acid, and polyoxyethylene monomethacrylate. . 11. A method for producing a resin aqueous emulsion according to any one of claims 8 to 10, which is obtained by emulsion polymerization at a pH of 6 to 10. 12. A method for producing a resin aqueous emulsion according to any one of claims 8 to 10, which is obtained by emulsion polymerization at a pH of 6.5 to 9. 13. The method according to claim 8, wherein the amount of 1,2,2,6,6-pentamethyl-4-piperidinyl methacrylate relative to the radical polymerizable monomer is 0.1%.
To 200 parts by weight of a resin aqueous emulsion. 14. The method according to claim 8, wherein the amount of 1,2,2,6,6-pentamethyl-4-piperidinyl methacrylate relative to the radically polymerizable monomer is 0.5.
To 10 parts by weight of a resin aqueous emulsion.