JP2657216B2 - Paint composition - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a coating composition comprising, as an essential component, an ultrafine aqueous emulsion obtained by emulsion polymerization of an unsaturated monomer.

(Prior art)

In recent years, from the viewpoints of air pollution, improvement of work environment on site, and effective use of resources, etc., as an alternative to organic solvent type paints, aqueous or water-dispersed water-based paints, powder paints, especially water-dispersed paints, that is, aqueous emulsions -Based paints are receiving attention.

However, for example, an aqueous emulsion paint obtained by emulsion polymerization of an unsaturated monomer in the presence of an emulsifier has a large particle size, and a formed film is more transparent and smoother than an organic solvent type paint film. However, there is a defect that the performance such as water resistance, solvent resistance and the like is inferior.

In order to improve these drawbacks, a redox catalyst consisting of a persulfate and a reducing sulfoxy compound, a polymerization initiator added with a trace amount of a transition metal ion as an accelerator, and ultrafine particles of an aqueous emulsion were used. And a method for improving the film performance by forming an appropriate three-dimensional structure in an aqueous emulsion (JP-A-60-170604, JP-A-60-170604).
No. -170605) has been proposed.

However, in these methods, due to the effect of a small amount of transition metal ions used as a polymerization accelerator,
Even when the particle size of the resulting aqueous emulsion is significantly different or ultrafine particles can be formed, the dispersion effect of the surfactant used after emulsion polymerization is small, and the viscosity of the generated aqueous emulsion is significantly increased. Alternatively, there is a problem that it is necessary to add aqueous ammonia or ammonium phosphate during the polymerization.

Furthermore, although the aqueous emulsion obtained by this method is crosslinked within and / or between particles, the film-forming property, transparency or mechanical strength of the film is poor due to the effect of the temperature at which the film is formed. And it was not an industrially advantageous method.

A method has also been proposed in which a certain type of polyoxyalkylene (meth) acrylic acid diester is used as a resin modifier to obtain an aqueous emulsion and improve the water resistance and the like of a film to be formed (Japanese Patent Publication No. 54-19905). However, in these methods, polyoxyalkylene (meth) acrylate diester has poor water-solubility and emulsifying power as well as not being able to form ultrafine particles, and the film performance such as water resistance is improved if not used in large amounts. In addition, there was a problem that the film was sticky and the tackiness was too strong.

〔Purpose〕

The object of the present invention is to form a film, transparency, smoothness, tackiness,
An object of the present invention is to provide an ultrafine-particled crosslinked aqueous emulsion-based coating composition having excellent water resistance and mechanical strength.

〔Constitution〕

According to the present invention, an aqueous emulsion comprising resin particles having an average particle diameter of 100 nm or less, having a crosslinked structure, and having a glass transition temperature lower than the value calculated by the weight fraction method is used as an essential component. Is provided.

First, the aqueous emulsion, which is an essential component of the coating composition of the present invention, is required to have an average particle size of 100 nm or less, preferably 80 nm or less.

Aqueous emulsions are essentially formed by filling and fusing particles, so that the average particle size is required to be small.In the present invention, the average particle size is 100 nm or less as described above. Since it is preferably limited to 80 nm or less, it becomes possible to greatly improve various properties such as heat fusion, transparency, smoothness, and glossiness of the film.

When the average particle size exceeds 100 nm, the adhesiveness (denseness) when a film is formed is poor, and the transparency, glossiness, and smoothness of the film may be lacking. You cannot achieve your goals.

The second feature of the aqueous emulsion, which is an essential component of the coating composition of the present invention, is that it has a crosslinked structure within and / or between the particles.

That is, the aqueous emulsion, which is an essential component of the coating composition of the present invention, is formed between the particles, for example, the functional groups of the raw material unsaturated monomers, or these and the functional groups of the emulsifier have an ionic bond, a hydrogen bond, Since it is crosslinked by a condensation reaction or a polymerization reaction, it is presumed to form a film having excellent transparency, tackiness, water resistance and mechanical strength.

Furthermore, a third feature of the aqueous emulsion, which is an essential component of the coating composition of the present invention, is that the glass transition is lower than the value calculated by the weight fraction method, preferably 3 ° C. or higher, more preferably 5 ° C. or higher. An aqueous emulsion having a temperature is an essential component.

The glass transition temperature (Tg) is the temperature at which a polymer changes from a glassy hard state to a rubbery state when heated, and if the glass transition temperature of a component that is a structural factor of the polymer is known, the polymer has a glass transition temperature. The glass transition temperature can be determined from the following equation by a polymerization fraction method.

W _A ; Weight fraction of A component W _B ; Weight fraction of B component Tg _A ; Glass transition temperature of A component Tg _B ; Glass transition temperature of B component This glass transition temperature is affected by various structural factors, and is generally In the case of a polymer having a crosslinked structure, its glass transition temperature becomes high, and 5 to 7 ° C depending on the degree of crosslinking.
It is known that the glass transition temperature may increase when a plasticizer is added to the polymer.

On the other hand, in the case of an aqueous emulsion, the lowest film formation temperature is known as the lowest temperature at which a film is formed by filling and fusing particles, and there is a proportional relationship between this minimum film formation temperature and the glass transition temperature. Recently, the present inventors have found that ultrafine particles having a crosslinked structure and having a minimum film forming temperature or a glass transition temperature of a formed film lower than a value calculated by a weight fraction method, and forming a film having excellent mechanical strength. An aqueous emulsion was found, and it was found that this was useful as a coating composition.

That is, although the aqueous emulsion used in the present invention has a film-forming ability showing a glass transition temperature lower than the value calculated by the weight fraction method as described above, despite having a crosslinked structure, it differs from the conventional one. It shows an excellent plasticizing effect, and since the glass transition temperature of the film to be formed is lowered, the minimum film forming temperature is also reduced in proportion to this, so that even at room temperature it is easily excellent in transparency, tackiness, and smoothness Further, a hard film having good mechanical strength such as tensile strength and modulus strength can be formed. In this case, as is apparent from the comparative examples described later, when the glass transition temperature of the film to be formed is higher than the value calculated by the weight fraction method, the aqueous emulsion does not sufficiently exhibit the plasticizing effect. At room temperature, the film does not form at room temperature, or even if it forms, it forms cracks and network streaks in the film, forming a film with excellent transparency, smoothness and tackiness as in the present invention. Can not do it.

Further, since it is hard and lacks mechanical strength such as low tensile strength and modulus strength, it is difficult to obtain a hard tough film.

Another feature of the aqueous emulsion used in the present invention is that it has excellent dispersion stability over a long period of time.

That is, the aqueous emulsion, which is an essential component of the coating composition used in the present invention, has an average particle size of 100 nm or less, and is subjected to a forced heating dispersion test at 45 ° C. for one week. Also, there is substantially no change in the average particle size, and even if there is a change, usually the average particle size is 15
It shows a particle size distribution of one peak distribution of particle distribution of 0 nm or less, and even when the rate of change is large, the particle size distribution of the first peak having an average particle diameter of less than 150 nm is 97% or more, which is due to aggregation of particles. The second peak has a very small peak of 3% or less having a particle size distribution of 300 nm or more, and has a double peak distribution, and the particle size distribution of the average particle diameter is extremely small.

Furthermore, the aqueous emulsion, which is an essential component of the coating composition used in the present invention, has an extremely small change rate of the average particle diameter even when subjected to a long-term storage stability test at 25 ° C. for 6 months.

Therefore, the aqueous emulsion according to the present invention is substantially free of coalescence or aggregation of particles even with the lapse of time, and does not generate coarse particles, so that the particle size changes with time, the transmittance decreases, Since there is no change in viscosity and no change in appearance, it exhibits excellent dispersion stability over a long period of time and has extremely high storage stability.

The reason why the aqueous emulsion, which is an essential component of the coating composition of the present invention, exhibits excellent dispersion stability as described above is not necessarily clear, but since the average particle size is 100 nm or less, Brownian motion between the particles is caused. Is relatively active, and because the polymerizable emulsifier does not remain in the system, the properties of each particle surface, etc., each particle is sufficiently protected, so that the particles coalesce or aggregate. This is presumed to be a fundamental factor in that the formation of coarse particles is not promoted.

Further, in the present invention, in order to further improve the dispersion stability of the aqueous emulsion, for example, P-hydroxydiphenylamine, N, N'-diphenyldiamine,
Conventionally known polymerization inhibitors and polymerization terminators such as 2,5-di-tert-butylhydroquinone can also be added.

The average molecular weight of the cross-linked aqueous emulsion, which is an essential component of the coating composition of the present invention, is generally one million or more, often about tens of millions to hundreds of millions, and has a high degree of cross-linking. In some cases, the molecular weight may be as high as tens of millions to one billion.

 Hereinafter, the present invention will be described in more detail.

The aqueous emulsion, which is an essential component of the coating composition of the present invention, can be easily obtained by emulsion polymerization of an unsaturated monomer.

As the unsaturated monomer, (meth) acrylic esters represented by the following general formula (I) (Wherein R ₁ and R ₂ are hydrogen or a methyl group, and R ₃ is an alkyl group having 1 to 18 carbon atoms), as well as vinyl acetate, vinyl propionate, vinyl butyrate and other lower fatty acid vinyl esters, acrylonitrile,
Nitriles such as metachronitrile, styrene, α-methylstyrene, styrenes such as chlorostyrene, vinyl chloride, vinyls such as vinyl bromide, vinylidene chloride,
Examples thereof include vinylidenes such as vinylidene bromide, dienes such as butadiene, chloroprene and isoprene, and vinylpyridine, and (meth) acrylates,
The use of lower fatty acid vinyl esters and styrenes is preferred.

Further, in the emulsion according to the present invention, as an unsaturated monomer to be copolymerized with the unsaturated monomer, in order to further strengthen the crosslinked structure within and / or between the particles of the aqueous emulsion to be formed. Unsaturated monomers having a reactive functional group are preferably used, but even unsaturated monomers having no reactive functional group can be converted into a compound having active hydrogen in an emulsion polymerization system. The use of monomers is also possible.

Examples of such an unsaturated monomer having a reactive functional group include compounds represented by the following general formulas (II) to (VIII). These monomers can be used alone or in combination of two or more kinds, and if necessary, other copolymerizable unsaturated monomers can be used in combination.

(Where R ₁ , R ₂ , R ₄ , R ₅ , R ₆ , R ₇ , R ₈ , R ₉ , B, D, E, t ₁ , t ₂ and t ₃
Is as follows.

R ₁ , R ₂ ; a hydrogen atom or a methyl group R ₄ ; an alkylene group having 2 to ₄ carbon atoms R ₅ ; a direct bond, an alkylene group having 1 to 3 carbon atoms, a phenylene group or a substituted phenylene group R ₆ ; an oxygen atom or- NH- R _7; alkylol groups R ₈ hydrogen or a 1 to 5 carbon atoms; hydrogen, an alkyl group R ₉ alkylol group or 1-5 C1-5 atoms; alkylene group having 1 to 4 carbon atoms a; methylene group or a carbonyl group B; -CH ₂ O- or a carboxyl group D; hydrogen atom, an alkyl group having 1 to 3 carbon atoms, carboxyl group, Or -CONHCONH ₂ E; hydrogen atom, an alkyl group having 1 to 3 carbon atoms or -CH ₂ COO
H t ₁ ; a real number of ₁ to 20 t ₂ ; an integer of 0 or 1 t ₃ ; an integer of 0 to 10) General formulas (II), (III), (IV), (V), (VI),
Examples of specific compounds of (VII) and (VIII) include:
The following can be mentioned.

Examples of general formula (II) Glycidyl acrylate Glycidyl methacrylate Glycidyl crotonate Glycidyl allyl ether Examples of general formula (III) Hydroxyethyl acrylate Hydroxyethyl methacrylate Hydroxyethyl crotonate Hydroxypropyl acrylate Hydroxypropyl methacrylate Hydroxypropyl crotonate Hydroxybutyl acrylate Hydroxybutyl methacrylate Polyoxyethylene monoacrylate Polyoxyethylene monomethacrylate Polyoxyethylene monotonate Polyoxypropylene monoacrylate Polyoxypropylene monomethacrylate Polyoxypropylene monotonate Polyoxybutylene monoacrylate Polyoxybutylene monotonate Hydroxy Tyl allyl ether hydroxypropyl allyl ether hydroxybutyl allyl ether polyoxyethylene allyl ether polyoxypropylene allyl ether polyoxybutylene allyl ether Examples of general formula (IV) allylamine acrylamine methacrylamine aminostyrene α-methylaminostyrene general formula (V ) Examples Acrylamide Methacrylamide Aminopropylmethacrylamide Monomethylacrylamide Monoethylacrylamide Diethylolaminopropylacrylamide Example of the general formula (VI) Acrylic acid Methacrylic acid Crotonic acid Itaconic acid Maleic acid and its monoester of alkyl group having 1 to 5 carbon atoms Or anhydride fumaric acid and its monoester or anhydride of an alkyl group having 1 to 5 carbon atoms De-fumaric acid alanide N-carbamoyl fumaric acid amide N-carbamoyl fumaric acid amide Example of general formula (VII) Methyl allyl thiol methyl mercaptostyrene Example of general formula (VIII) N-methylol acrylamide N-methylol methacrylamide N- Methylolcrotonamide N- (2-hydroxyethyl) acrylamide N- (2-hydroxyethyl) methacrylamide N- (2-hydroxypropyl) acrylamide N- (2-hydroxypropyl) methacrylamide The ratio of the saturated monomer and the unsaturated monomer having a reactive functional group to be used is 99/1 to 60/40 (weight), preferably 99/1 to 90/10 (weight). This usage rate is 99/1
If it is larger, the degree of cross-linking within and between the particles of the polymer latex to be formed becomes small, and if it is smaller than 60/40, a large amount of agglomerates may be formed due to lack of emulsion copolymerizability or poor film-forming properties. Cracks may occur in the film.

The emulsifier used when the aqueous emulsion, which is an essential component of the coating composition of the present invention, is emulsion-polymerized using the above unsaturated monomer, is 3% from the value calculated by the weight fraction method as described above. Any emulsifier can be used as long as it forms a film having a low glass transition temperature of at least ° C, but particularly preferred emulsifiers include the following general formula (IX)
(Hereinafter abbreviated as a poly (meth) acryloyl-type emulsifier) represented by the following general formulas (X), (XI), and (XI)
Examples include betaine ester type emulsifiers represented by I), (XIII) and (XIV) and ether carboxylic acid type emulsifiers represented by formulas (XV), (XVI) and (XVII).

(Wherein R ₁ , R ₂ , R ₁₀ , R ₁₁ , R ₁₂ , R ₁₃ , R ₁₄ , R ₁₅ , R ₁₆ , R ₁₇ , R ₁₈ ,
a ₁ , a ₂ , a ₃ , a ₄ , a ₅ , a ₆ , a ₇ , a ₈ , a ₉ , a ₁₀ , G, J, L, M, T, X, Y and V are as follows It is.

R ₁ , R ₂ ; hydrogen or a methyl group R ₁₀ ; an alkylene group having 2 to 4 carbon atoms R ₁₁ ; an alkyl group or an alkenyl group having 8 to 30 carbon atoms, which may be linear or branched, and preferably those R ₁₂ of 8 to 18 carbon atoms; alkylene group R ₁₃ having 1 to 5 carbon atoms, R _14, R _15; an alkyl group having 1 to 3 carbon atoms or -C ₂ H ₄ OH, respectively be identical or different Is also good.

R ₁₆ , R ₁₇ ; an alkyl group having 6 to 20 carbon atoms or hydrogen,
At least one of them is an alkyl group having 6 to 20 carbon atoms R ₁₈ ; hydrogen, an alkyl group having 1 to 30 carbon atoms or an alkenyl group a ₁ , a ₂ , a ₃ , a ₄ , a ₅ , a ₆ , a ₇ A ₁ ; a real number of _{1 to} 50; preferred addition mole number of alkylene oxide in the molecule is 8 or more a ₂ ; a real number of 0 to 20 a ₃ ; one of R ₁₄ and R ₁₅ Is an alkyl group,
A real number of 0 to 20, a real number of 1 to 30 when both R ₁₅ and R ₁₆ are alkyl groups a ₄ ; a real number of 1 to 30 a ₅ ; a real number of 0 to 20 a ₆ ; a real number of 0 to 20 a ₇ ; real number of 0 to 20 a ₈ ; integer of 0 or 1 a ₉ ; real number of 2 to 20 p; integer of 2 to 5 q; integer of 0 to 3 _{-O-CnH 2 n - g 2} (R 21) g 2 -O- R 19, R 20; hydrogen or number 1-2 alkyl group R ₂₁ carbons; hydrogen or R ₁₀ Oa ₁₀ H or n; an integer of _{1 to} 10 g ₁ ; an integer of 0 to 5 g ₂ ; an integer of 0 to ₁₀ a ₁₀ ; a real number of 2 to 50 And y is a real number of 1 to 5 R ₂₂ , R ₂₃ ; hydrogen or an alkyl group having 1 to 20 carbon atoms Y ′; an alkylene group having 3 to 8 carbon atoms, oxygen or a carbonyl group J; L; an alkylene group having 1 to 5 carbon atoms or T; direct bond, oxygen, sulfur M; hydrogen or inorganic anion X; inorganic anion or organic anion V; hydrogen or halogen Also, any of these emulsifiers can be used alone. In order to obtain an ultrafine cross-linked aqueous emulsion having a dense and higher cross-linked structure inside and between particles and forming a film having a glass transition temperature lower than the value obtained from the calculation formula, the unsaturated monomer (A) as an emulsifier used for emulsion polymerization of a product
A poly (meth) acroyl-type emulsifier represented by the above general formula (IX), (b) the above general formula (X), (XI), (XII),
(XIII), betaine ester type emulsifiers represented by (XIV) and (c) ether carboxylic acid type emulsifiers represented by the above general formulas (XV), (XVI) and (XVII) as (a) / (b)
= 1/9 to 9/1 or (a) / (c) = weight ratio of 1/9 to 9/1,
It is preferably used in a weight ratio of 1/4 to 4/1. If the use ratio is less than 1/9, the degree of crosslinking within and / or between the particles of the resulting aqueous emulsion becomes small, and if it is more than 1/9, the average particle diameter of the produced aqueous emulsion may become large.

In addition, known anionic, nonionic and cationic surfactants may be added as necessary. Specific examples thereof include higher alcohols, higher alcohol alkylene oxide adducts, alkylphenol alkylene oxide adducts and styrenated. A quaternary ammonium salt type of each of a phenol alkylene oxide adduct sulfate type, an olefin sulfonate type such as α-olefin, a long-chain alkylamine alkylene oxide adduct and a di-long chain alkylamine alkylene oxide adduct, N- (1, Examples thereof include sodium salt of 2- (dicarboxyethyl) -N-octadecylsulfonic acid monoamide, dialkylsulfosuccinate and the like.

When a betaine ester is used as an emulsifier for obtaining an aqueous emulsion which is an essential component of the coating composition of the present invention, it is desirable to adjust the pH in the emulsion polymerization step to less than 6, preferably 3 to 6. If the pH is 6 or more, a large amount of aggregates having properties significantly different from those of the aqueous emulsion of the present invention are formed in the emulsion polymerization step, which is not preferable.

In obtaining the aqueous emulsion used in the present invention, a conventionally known emulsion polymerization method can be used as it is in the presence of the unsaturated monomer and the emulsifier. For example, in the presence of a polymerization initiator corresponding to 0.1 to 5% by weight of the unsaturated monomer, the polymer of the unsaturated monomer is 20 to 60%.
The emulsion polymerization may be performed by emulsifying and dispersing in water at a concentration of weight%.

As the polymerization initiator, a water-soluble single initiator or a water-soluble redox initiator used for ordinary emulsion polymerization are used.For example, such as hydrogen peroxide alone or hydrogen peroxide and tartaric acid, citric acid, In addition to combinations with carboxylic acids such as ascorbic acid, and combinations of hydrogen peroxide with oxalic acid, sulfinic acid and salts or oxyaldehydes thereof, and water-soluble iron salts, etc., as well as persulfates, percarbonates, and peroxides Peroxides such as borates, 2,2'-azobis (2-aminodipropane) and its salts, 2,2'-azobis (N, N'-dimethylene-isobutylamidine) and its salts, 4,4 ' Water-soluble azo initiators such as -azobis (4-cyanovaleric acid) and salts thereof can be used.

In addition, a water-soluble nonionic polymer, an anionic polymer, a cationic polymer, or the like can be used in combination. Further, a plasticizer and a pH adjuster usually used in the conventional method can be used together if necessary.

Examples of the nonionic polymer substance include polyvinyl alcohol, dextrin, hydroxyethyl starch, starch derivatives such as hydroxyethyl cellulose, hydroxyethyl cellulose, hydroxypropyl cellulose, and the like.

Examples of the anionic polymer substance include polymers such as anionized hydroxyethyl cellulose, anionized starch, anionized guar gum, anionized chitosan, carboxymethylcellulose, and anionized polyvinyl alcohol.

Examples of the cationic polymer substance include cationized hydroxyethyl cellulose, cationized starch, cationized guar gum, cationized chitosan, and cationic (meth) acrylamide, cationic (meth) acrylamide, dimethyldiallylammonium chloride. And the like.

These nonionic high-molecular substances, anionic high-molecular substances and cationic high-molecular substances can be used as appropriate, or two or more types can be used. It is suitable to use 5% by weight, preferably 0.1-3% by weight.

Further, phthalic acid esters, phosphoric acid esters and the like can be used as the plasticizer. Further, salts such as sodium carbonate, sodium bicarbonate and sodium acetate are used as pH adjusters.
Although it can be used in the range of 01 to 3% by weight, as described above,
When a betaine ester type emulsifier is used, it is desirable to use it so as to adjust the pH to less than 6.

The coating composition of the present invention contains the above specific aqueous emulsion as an essential component.If necessary, various colored pigments, extender pigments, rust preventive pigments, antibacterial agents, fungicides, extenders, fillers Various auxiliary components usually used in this type of coating material, such as a dispersant, a viscosity modifier, an antifoaming agent, and a crosslinking agent such as a water-soluble melamine (resin) when it is necessary to crosslink the coating film. It can be arbitrarily added.

Preferred applications of the coating material include a wide range of applications from currently used aqueous coating materials to solvent-based coating materials. Specific examples thereof include wood-based products, plastic products, metal products, civil engineering structures, and vehicles for clear coating or emulsion coating for undercoats and topcoats of automobiles, railway vehicles and the like, as well as water-soluble melamine ( Resin and the like, and can be used as a baking coating material for baking and curing (crosslinking), and also as a blending agent for improving the coating properties of water-soluble coatings, powder coatings, and high solid coatings.

Further, the coating composition of the present invention has remarkably good thixotropic properties and film-forming properties, has excellent water resistance, and forms a tough film. Also, by mixing with a metal powder, it can also be used as a radiation-shielding paint such as a magnetic paint, a conductive paint, an electromagnetic tension shield material, a marker ink, and a nail polish.

〔effect〕

The coating composition of the present invention has an average particle size of 100 nm or less,
Has a crosslinked structure, 3 ° C higher than the value calculated by the weight fraction method
Since an aqueous emulsion having a low glass transition temperature is an essential component, unlike conventional coating compositions, a coating film having excellent film forming properties, transparency, smoothness, tackiness, water resistance and mechanical strength is formed. It has a function.

For this reason, the coating material of the present invention is applied to various base materials such as wood products, plastic products, mortar products, concrete products, metal products and the like and to the surfaces of the products, thereby providing transparency and water resistance to these base materials. Various excellent performances such as heat resistance, weather resistance and impact resistance can be imparted.

Further, since the coating composition of the present invention is a solvent-free coating composition, it also has the advantage of being excellent in safety and being pollution-free.

〔Example〕

Next, in order to explain the present invention in more detail, examples are shown below.

Example 1 [Preparation of aqueous emulsion] 8 parts by weight of the emulsifier shown in Table 1 and 150 parts by weight of water were charged and dissolved in a glass reactor equipped with a thermometer, a stirrer, a reflux condenser, a nitrogen inlet, and a dropping funnel. Then, the inside of the system was replaced with nitrogen gas. Separately, 75 parts by weight of ethyl acrylate, 75 parts by weight of methyl methacrylate, 4.5 parts by weight of N-methylolacrylamide and 156 parts by weight of an unsaturated monomer mixture composed of 1.5 parts by weight of water were prepared, and 15 parts by weight of these were prepared. The mixture was added to the reaction vessel and emulsified at 40 ° C. for 30 minutes. Then, after the temperature was raised to 60 ° C., the polymerization initiator 2,2′-azobis (N, N′-dimethyleneisobutylamidine) hydrochloride was added to 9.0 × 10 ⁻³ mole /
It was dissolved in 48.5 parts by weight of water so as to become an aqueous phase, added to the above reaction vessel, and immediately the remaining unsaturated monomer was continuously dropped into the reaction vessel over 30 minutes, and the polymerization was carried out at 60 ° C. went. After completion of the dropwise addition of the unsaturated monomer, the mixture was aged at 60 ° C. for 60 minutes.

(Evaluation of aqueous emulsion)

The average particle size, crosslinkability, film forming property, and glass transition temperature of the aqueous emulsion thus obtained were measured by the following methods.

Average particle size: Coulter submicron particle analyzer (Coulter Electronics, USA, Coulter
(Model N4 type).

Crosslinked product: 30 g of an aqueous emulsion adjusted to have a solid content of 40% by weight was cast uniformly on a glass plate of 12 cm × 14 cm and air-dried at 25 ° C. The film thus obtained was cut into 2 cm × 4 cm, immersed in a petri dish filled with benzene at 20 ° C. for 48 hours, and evaluated based on the degree of swelling and solubility of the film as follows.

；: Equal to or slightly swelling with the film area (2 cm × 4 cm) before immersion in benzene.

Δ: The degree of swelling is large and the film shape is impaired.

X: The film was dissolved in benzene and turned into a uniform liquid.

Film-forming property; air-dried at 25 ° C. to form a film, and the shape of the formed film was visually evaluated.

；: A smooth and uniform film is formed.

Δ: A film having a network streak is formed.

X: No film is formed.

Glass transition temperature (Tg) Thermal diffraction analyzer (SSC 5000, manufactured by Seiko Denshi Kogyo Co., Ltd.)
Tg was measured using DSC 200). The calculated Tg was calculated by the weight fraction method (described above).

[Evaluation of film properties]

The above aqueous emulsion 30 having a solid content adjusted to 20% by weight.
The parts by weight were uniformly cast on a glass plate of 12 cm × 14 cm and air-dried at room temperature to form a film, and the film characteristics were evaluated. The film characteristics were evaluated according to the following criteria.

Transparency: According to JIS K 6714, the haze value of the film was measured with an integral light transmittance measuring device.

Water resistance: The film was cut into a size of 2 cm × 4 cm, immersed in a petri dish filled with water at 20 ° C., and the whitening state of the film was visually determined.

；: The film is transparent.

Δ: The film is translucent.

X: The film is opaque.

Adhesive: The film surface was touched with a finger, and the stickiness was evaluated according to the following criteria.

○: No stickiness △: Slightly sticky ×: Sticky Elongation and strength: Dumbbells were prepared in accordance with JIS K-6681, tensile strength at break, elongation and 50%, 100% and 200% modulus. Was measured.

[Performance evaluation as paint]

5.0cm x 5.0cm x 1.0cm mortar board, Masamaki birch wood and 20cm x 10cm x 0.4cm steel sheet (SS41) are cleaned with a polyoxyethylene nonyl phenyl ether (EO = 9.7) aqueous solution to remove fouling components on the surface. Remove, wash with water, air dry at room temperature,
Solid content 40% by weight so that the resin layer becomes 0.2mm on this surface
Of the above aqueous emulsion was uniformly applied.

Then, after air-drying at 25 ° C, the appearance (glossiness), water resistance, salt water resistance and impact resistance of the mortar board, raw birch wood and the clear coating of the steel sheet according to the following standards according to JIS K-5400 Was evaluated.

Appearance (glossiness) ；: The coating film is transparent and has the original gloss of the material to be coated.

Δ: The coating film was slightly translucent, the original gloss of the material to be coated was slightly inferior, and the coating film surface had some retinal streaks.

X: The coating film is translucent and does not have the original gloss of the material to be coated.

Water resistance and salt water resistance ；: There is no wrinkle, swelling, cracking or peeling on the coated surface.

Δ: There are some wrinkles, swelling, cracks and peeling on the coated surface.

X: There are wrinkles, swelling, cracks and peeling on the painted surface.

Impact resistance ；: There is no cracking or peeling in the film.

Δ: There are some cracks and peeling in the film.

X: The film has cracks or peeling.

By the above method, the properties of the aqueous emulsion, the film properties, and the performance as a paint were evaluated. Table 1 shows the results.
And Table-2. Samples Nos. 1 to 4 are examples of the present invention, and show that the skin (coating) film is remarkably excellent in water resistance and mechanical strength, and is a good coating composition. Sample No.5
7 are comparative examples.

In addition, a dumbbell was prepared from the aqueous emulsion of Sample No. 1 (the present invention) and Sample No. 5 (Comparative Example) in accordance with JISK-6781, and a stress-strain test was performed. The result is shown in the drawing. As is clear from the drawings, the product of the present invention is
It is understood that a hard and extremely tough film is formed.

Example 2 8.0 parts by weight of an emulsifier shown in Table 3 and ethyl acrylate 9
0 parts by weight, 60 parts by weight of methyl methacrylate, 157 parts by weight of an unsaturated monomer comprising 4.5 parts by weight of N-methylolacrylamide and 2.5 parts by weight of water, and potassium persulfate 3.0 × 10 ^-3 mole / Aqueous phase, sodium thiosulfate 3.
An aqueous emulsion was prepared by dissolving in 47.5 parts by weight of water so as to be 0 × 10 ⁻³ mole / aqueous phase and copper sulfate 5.0 × 10 ⁻⁵ mole / aqueous phase, and performing emulsion polymerization in the same manner as in Example 1. did.

Properties of the aqueous emulsion thus obtained, 20
The characteristics of the film formed by air drying at ℃ and the performance as a paint were measured and evaluated in the same manner as in Example 1. The results are shown in Tables 3 and 4. Samples Nos. 8 to 11 are examples of the present invention,
Samples Nos. 12 to 14 and 14 'are comparative examples.

Example 3 154.5 parts by weight of an unsaturated monomer mixture comprising 60 parts by weight of n-butyl acrylate, 90 parts by weight of styrene and 4.5 parts by weight of 2-hydroxyethyl methacrylate, and 8.0 of the following emulsifier:
Parts by weight And a polymerization initiator shown in Table 5 was dissolved in 50 parts by weight of water so as to be 9.0 × 10 ^-3 mole / water phase, and emulsion polymerization was carried out in the same manner as in Example 1 at a polymerization ripening temperature shown in Table-5. And an aqueous emulsion was prepared. The properties of the obtained aqueous emulsion, the film properties obtained by air drying at 20 ° C., and the performance as a paint were measured in accordance with Example 1. The results are shown in Table-5 and Table-6.

Samples Nos. 15, 16, 17, 19, 20, and 21 are examples of the present invention, and samples Nos. 18 and 22 are comparative examples.

The mechanical strengths of the coatings of Sample Nos. 15 to 17, 19, 20 and 21 were all 150% or more in elongation and 150 kg / cm ² or more in tensile strength (breaking strength).
In each case, the film forming property was good at 20 ° C. or less.

Example 4 The following emulsifiers E-1 to E-5 in parts by weight shown in Table-7. C ₁₂ H ₂₅ O-C ₃ H ₆ O-C ₂ H ₄ O _2.0 COONa E-2 Separately, the following unsaturated monomer mixtures M-1 to M-
3 And emulsion polymerization was carried out in the same manner as in Example 1 to prepare an aqueous emulsion. The properties of the obtained aqueous emulsion, the characteristics of a film formed by air drying at 25 ° C., and the evaluation as a paint were measured in accordance with Example 1. The results are shown in Table-7.

Sample Nos. 23 to 34 are examples of the present invention. Sample No.23
The mechanical strength of each of the ~ 34 films is 150% or more,
The tensile strength (strength at break) was 150 kg / cm ² or more. In the same manner as in Example 1, the performance evaluation as a paint was performed using the aqueous emulsions of Sample Nos. 23 to 24. As a result, all of the aqueous emulsions of Sample Nos. 23 to 34 showed performance as a paint having excellent appearance (glossiness), water resistance, salt water resistance and impact resistance.

Example 5 The solid content of the aqueous emulsions of Samples Nos. 8 to 11 obtained in Example 2 was adjusted to 40% by weight, and alumina (purity: 99.0% by weight,
A pigment having an average particle diameter of 0.5 μm (Showa Metal Co., Ltd.) was added, and 200% by weight based on the solid content of the aqueous emulsion was added.
Stir and mix with a homomixer (1000 rpm x 10 minutes).

The pigment-mixed aqueous emulsion was washed with petroleum ether on a steel plate (SS41, 20.0 cm x 10.0 cm x 0.4 cm) with a thickness of 0.2 mm.
mm, air-dry at 20 ° C, JISK5400
The appearance (glossiness), water resistance, salt water resistance and impact resistance were measured according to the method described in Example 1, and evaluated according to Example 1.

The results were all good and showed an excellent effect as a coating film.

Example 6 The solid content of the aqueous emulsions of Sample Nos. 8 to 11 obtained in Example 2 was adjusted to 40% by weight, and a titanium white pigment (Titanium Kako Co., Ltd. Titanium White RK) and a defoamer (San Nopco Co., Ltd. 803
4) was added in an amount of 150% by weight and 0.6% by weight, respectively, based on the solid content of the aqueous emulsion, and a homomixer (1000 rpm ×
10 minutes) and mixed.

This pigment-mixed aqueous emulsion is applied by spraying to a zinc phosphate-treated steel sheet (22.0 cm × 10.0 cm × 0.4 cm) washed with petroleum ether, and heated at 130 ° C. for 30 minutes to form a film having a thickness of 50 μm.
A μm coating was formed. This coating film was measured for water resistance, salt water resistance and impact resistance according to JISK5400, and evaluated according to Example 1. The results were all good and showed an excellent effect as a coating film.

In addition, 5 g of the aqueous emulsion of Sample Nos. 8 to 11 adjusted to a solid content of 20% by weight was cast uniformly on a 5 cm × 6 cm glass plate and air-dried at 25 ° C. The film thus obtained was further heat-treated at 160 ° C. for 3 hours, and the yellowness of the film before and after the heat treatment was measured using an SM color computer manufactured by Suga Test Instruments Co., Ltd.
It was measured by SM-4-CH type (45 ° diffusion method). The results were 3 or less before heat treatment, 10 or less after heat treatment,
There was no yellowing problem.

From the above results, it is understood that the coating composition of the present invention is also suitable as a baking coating.

Example 7 The sample Nos. Of Examples 1, 2, 3 and 4 in which the pH was adjusted to 7 and the solid content concentration was adjusted to 40% by weight using water and triethanolamine.
A predetermined amount of the aqueous emulsions of 1,8,9,15,17 and 28, calcium carbonate and asbestos are charged into a kneader, and while mixing, a predetermined amount of sodium phosphate dibasic and water are added and uniformly mixed. At this time, the water has a viscosity of the automotive standard (JASO-
7006 (1 type B)) to add the consistency (about 350).

Aqueous emulsion; 85 parts by weight Calcium carbonate; 25 parts by weight Asbestos; 8 parts by weight Sodium diphosphate; 0.5 part by weight Water; Balance
Evaluation as an underbody coating paint according to -7006 (Class B) was carried out with respect to storage stability, workability, baking test, oil resistance, boiling water resistance, impact resistance, abrasion resistance and vibration proofness. The results are shown in Table-8.

Table 8 shows that the coating composition of the present invention is also suitable as a coating for vehicles such as automobiles.

Example 8 Sample No. 3,9,10,17,20,28 and 33 of Examples 1,2,3 and 4 in which the solid content concentration was adjusted to 20% by weight. 0.2 parts by weight of a fluorescent compound or dye of rhodamine, rozamine or fluorescein was added and uniformly mixed to obtain a marking ink.

Fill this marking ink into a felt-tip pen having a polyester nib with a Shore hardness of 25 and a porosity of 57%, and add 100 g
It was written on a high-quality paper with a moderate load pressure. These results indicate whether or not clear images and prints with good leveling properties and no fog can be written. Or, after immersing the written portion directly after drying or in a 0.5 g water drop or benzene oil drop for 5 minutes,
Apply a load pressure of about 300g with the index fingertip and trace with your finger.
It was evaluated whether a clear image and print could be maintained.

The results are shown in Table-9. Table 9 shows that the coating composition of the present invention is excellent in glossiness, abrasion resistance, water resistance and solvent resistance, and is suitable for marking and manicure of marking pens, brush pens and the like.

Example 9 The dispersion stability of the aqueous emulsions of Samples Nos. 1 to 34 was evaluated in the following manner. Table 10 shows the results. In addition, the dispersion stability test was based on the following.

(Dispersion stability)

Aqueous emulsion 15 with solid content adjusted to 40% by weight
After putting 0 g in a 220 ml glass bottle and sealing, leave it in a constant temperature room at 25 ° C. for 6 months and leave it in a constant temperature room at 45 ° C. for 1 week, then measure the appearance, transmittance, viscosity and average particle size. The dispersion stability of the emulsion was evaluated. The appearance, transmittance, viscosity and average particle size were measured by the following methods.

Appearance: Visually evaluated at 25 ° C. according to the following criteria.

○: Transparent or translucent liquid △: Cloudy liquid ×: Cloudy paste or cloudy, separated into two layers Transmittance: Wavelength 800 using spectrophotometer (Digital Double Beam Spectrophotometer UVIDEC-320 manufactured by JASCO Corporation)
The absorbance under light irradiation of nm was determined, and the light transmittance (%) was calculated.

Viscosity: The viscosity at 25 ° C. was measured using a Brookfield viscometer (B-type viscometer manufactured by Tokyo Keiki Co., Ltd.).

Average particle size: Coulter submicron particle analyzer (Coulte Electronics Co., USA, Coulte
r, Model N4 type).

The aqueous emulsions of Samples 1-4, 8-11, 15-17, 19-21 and 23-34 subjected to the forced heating dispersion stability test, which was allowed to stand in a 45 ° C. constant temperature room for one week, were used in Example 1. A film was formed according to the method, and the film characteristics and the performance as a conductive film forming material were measured and evaluated according to Example 1. All of the same results as in Examples 1, 2, 3 and 4 were obtained in all of the transparency, water resistance, pressure-sensitive adhesive, solvent resistance (crosslinkability), mechanical strength, and performance as a conductive film forming material. was gotten. FIG. 2 (A) and FIG. 2 (B) are graphs showing changes in the particle size distribution before and after the dispersion stability test.

Sample No. 7 in Table 10 (1) had a large number of ultra-large particles after a standing test at 45 ° C. for one week and could not be measured due to poor dispersibility. Therefore, both Sample No. 1 and Sample No. The change in the particle size distribution after standing for a few months was illustrated and compared.

[Brief description of the drawings]

Fig. 1 shows a dumbbell made from an aqueous emulsion of the product of the present invention (Sample No. 1) and a comparative product (Sample No. 5; film formation temperature of 35 ° C.) in accordance with JISK-6781, and the measurement when a stress-strain test was performed. The result. Solid line: Inventive product Dashed line: Comparative product FIGS. 2 (A) and 2 (B) show the inventive product (sample No.
1) and an aqueous emulsion of the comparative product (Sample No. 7)
It is a graph showing the change of the particle size distribution after standing for 6 months at ° C.

Claims (1)

(57) [Claims] An aqueous emulsion comprising resin particles having an average particle diameter of 100 nm or less, having a crosslinked structure, and having a glass transition temperature lower than a value calculated by a weight fraction method is an essential component. Paint composition.