JPH0140846B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a novel aqueous emulsion composition, and more specifically, when it is applied as a coating composition onto a substrate, it has excellent water resistance and gloss, the surface does not show a sticky feeling even in the early stage of curing, and it does not cause yellowing. The present invention relates to a method for producing an aqueous emulsion composition that provides a coating film that is free of moisture. In recent years, water-based emulsion compositions have come to be used as resource-saving, non-polluting paints in place of oil-based paints in fields where oil-based paints have traditionally been used. However, emulsion compositions obtained using conventional ionic or nonionic low-molecular or high-molecular surfactants as dispersion stabilizers,
If a large amount of a film-forming agent is used, the emulsion system becomes unstable. In addition, in order to use the emulsion composition in this field, the film formed must be very dense, and for this reason, a water-soluble resin is usually added to the emulsion composition; usually contains a neutralizing agent and a water-soluble organic solvent, and these neutralizing agents and water-soluble organic solvents make the emulsion system very unstable, and in addition, ionic or It has not been put into practical use so far because it has drawbacks such as poor water resistance of the coating due to the use of nonionic low-molecular or high-molecular substances. Furthermore, when the above-mentioned conventional emulsion composition is used as an adhesive, there is a problem in that the surfactant in the composition oozes out onto the surface of the adhesive to which it is applied, staining the surface. Therefore, attempts have been made to obtain an aqueous emulsion composition that does not have the above-mentioned drawbacks of conventional aqueous emulsion compositions containing ordinary ionic or nonionic low-molecular or high-molecular surfactants as dispersion stabilizers. Various attempts have been made, one of which has been proposed to use a water-soluble resin as a dispersion stabilizer. For example, it has been proposed to use water-soluble resins such as water-soluble acrylic resins, maleated polybutadiene, maleated oils, and maleated alkyd resins as dispersion stabilizers. However, although the above-mentioned water-soluble acrylic resin is preferable in terms of performance, on the other hand, the hydrophilic part and the non-hydrophilic part in the above-mentioned molecular skeleton are not clearly separated, so
It is difficult to obtain an emulsion composition with excellent stability using this water-soluble acrylic resin as a dispersion stabilizer. For this purpose, various attempts have been made to modify the water-soluble acrylic resin into a block copolymer or graft copolymer, but to date no block copolymer or graft copolymer having the desired performance has been found. It has not been found. On the other hand, water-soluble resins such as maleated polybutadiene, maleated oil, and maleated alkyd resins are themselves soft resins and have many oxidative hardening groups, so it is difficult to disperse and stabilize these water-soluble resins. The aqueous emulsion composition used as the agent has limited applications because the surface of the cured coating film formed from it exhibits tackiness in the initial stage, and the coating film tends to yellow with long-term exposure. There was a big drawback: The present inventors have developed an aqueous emulsion composition that does not have the above drawbacks, that is, it has excellent dispersion stability, water resistance, yellowing resistance, gloss, and other properties, and the surface of the coating film is maintained even in the early stage of curing. As a result of extensive research aimed at providing an aqueous emulsion composition that forms a cured coating film that does not exhibit a sticky feeling and has a good texture, we found that one molecule contains an unsaturated group capable of radical polymerization and an unsaturated group capable of graft polymerization. We have found that the above objects can be achieved by an aqueous emulsion composition obtained by using a water-soluble resin as a dispersion stabilizer, which is composed of a monomer containing both unsaturated groups as an essential component. The present invention has been completed. Thus, according to the present invention, (a) one molecule contains the following formula: [In the formula, R represents a hydrogen atom or a methyl group,
R′ is

【formula】

[Formula] represents a phenylene or lower alkenylene group, R'' represents a hydrogen atom, a methyl group, or an ethyl group] One radically polymerizable unsaturated group and at least one graft polymerizable unsaturated group; (b) a monoester of α,β-ethylenically unsaturated acid and/or polyalkylene glycol with acrylic acid or methacrylic acid; and (c) other radically polymerizable unsaturated monomers. Provided is a method for producing an aqueous emulsion composition, which comprises emulsion polymerizing at least one radically polymerizable unsaturated monomer in the presence of a water-soluble resin consisting of a copolymer of the present invention. As in known aqueous emulsions, the aqueous emulsion composition obtained by this method contains a conventional ionic or nonionic low-molecular or high-molecular surfactant, or a water-soluble oxidation-curing resin known per se, in a stable dispersion. Since it is not used as an agent, the cured coating film formed from it has excellent properties such as water resistance, yellowing resistance, and gloss, and does not exhibit a sticky feeling.
There is an advantage. Furthermore, even when used as an adhesive, the dispersion stabilizer does not ooze out onto the surface and stain the adhesive surface. In addition, in the aqueous emulsion composition of the present invention, the above-mentioned specific water-soluble resin used as a dispersion stabilizer has a graft polymerizable property that has little chain transfer effect and can graft-form long side chains into the resin skeleton. Because it has an unsaturated group, even if a small amount is used, the water-soluble resin moderately grafts with the radically polymerizable unsaturated monomer to form a long side chain during emulsion polymerization, and at the same time, the radically polymerizable Since polymer particles are formed by emulsion polymerization of the unsaturated monomer itself, the grafted product and the polymer particles are well intertwined, resulting in an aqueous emulsion composition with extremely excellent dispersion stability. In the aqueous emulsion composition of the present invention, the water-soluble resin used as a dispersion stabilizer can be a resin that is itself water-soluble and has the ability to form a sufficiently durable film. . The water-soluble resin used in the present invention has (a) the following formula in one molecule: [In the formula, R represents a hydrogen atom or a methyl group,
R′ is

【formula】

[Formula] represents a phenylene or lower alkenylene group, R″ is a hydrogen atom,
Monomer containing one radically polymerizable unsaturated group and at least one graft-polymerizable unsaturated group; (b) α,β-ethylenically unsaturated group; A monoester of saturated acid and/or polyethylene glycol with acrylic acid or methacrylic acid; and (c) a copolymer prepared by copolymerizing other radically polymerizable unsaturated monomers. . The "radically polymerizable unsaturated group" contained in the above monomer component (a) is represented by the above formula (), and specifically, for example, CH ₂ =CHCOO-,
CH ₂ =C(CH ₃ )COO―,

【formula】

[Formula] CH ₂ = CHCONH―, CH ₂ = C(CH ₃ )CONH―, CH ₂
=CH-CH=CH-, etc. Among these, particularly preferred are CH ₂ =CHCOO- and
CH ₂ =C(CH ₃ )COO-. On the other hand, a "graft polymerizable unsaturated group" is a group derived from an unsaturated compound that has a hydrogen atom active against radical chain transfer reactions at the β-position of the unsaturated group, and is It exhibits low activity and can exist as a graft active site in the copolymer after radical polymerization of the monomer components (a), (b), and (c). A suitable group of such graft polymerizable unsaturated groups has the following formula:

【formula】

[Formula] [In the formula, R _{1 to 7} each represent H or a C _{1 to 8} alkyl group] In addition, other suitable groups of unsaturated groups include Groups derived from 5- or 6-membered ring compounds containing carbon-carbon double bonds, e.g.

【formula】

【formula】

【formula】

【formula】

Examples include [Formula]. Specific examples of the graft polymerizable unsaturated group represented by the above formula () or () include, for example, CH ₂ =CH—CH ₂ —O—, CH ₃ —CH=CH—
CH ₂ ―O―, CH ₂ =CH(CH ₃ )―CH ₂ ―O―,
CH ₂ = CH―CH(CH ₃ )―O―,

[Formula] etc., especially CH ₂ =CH-CH ₂ -O- and

[Formula] is preferred. The monomer component (a) can contain one radically polymerizable unsaturated group and one or more graft-polymerizable unsaturated groups, preferably 1 to 3, and furthermore, the monomer component In addition to the above two types of unsaturated groups, (a) can also contain an atomic group that is inert to polymerization, and the monomer (a) as a whole generally has a molecular weight within the range of 100 to 400. be able to. Specific examples of such monomer component (a) are as follows. (i) A monohydric alcohol selected from the group consisting of acrylic acid or methacrylic acid and allyl alcohol, ethylene glycol monoallyl ether, trimethylolpropane diallyl ether, and condensates of acrolein and trimethylolethane, trimethylolpropane, glycerin, etc. esterified product. (ii) Adducts of acrylic acid or methacrylic acid and allyl glycidyl ether. (iii) Hydroxyl group-containing acrylic monomers [for example, hydroxyalkyl (meth)acrylates such as hydroxyethyl acrylate, hydroxyethyl methacrylate, hydroxypropyl acrylate, and hydroxypropyl methacrylate, and the monohydric alcohols mentioned in (i) above, are combined with diisocyanates] A compound that is reacted with a compound (aliphatic, alicyclic, aromatic, etc. commonly used in the production of polyurethane). (iv) Esterified products of tetrahydrophthalic anhydride, hymic anhydride, etc. and hydroxyl group-containing acrylic monomers as described in (iii) above. In addition, the monomer components used to impart water solubility to the resulting copolymer resin, namely α, β
- Ethylenically unsaturated acid (b) has 3 carbon atoms
~22, preferably 3 to 6 aliphatic unsaturated mono- or di-carboxylic acids or anhydrides or monoesters of said dicarboxylic acids, and vinyl aromatic mono- or di-carboxylic acids having from 8 to 12 carbon atoms. Sulfonic acids are included, specific examples include acrylic acid, methacrylic acid, crotonic acid, itaconic acid, maleic acid, maleic anhydride, fumaric acid, maleic acid mono-
Examples include α,β-ethylenically unsaturated carboxylic acids such as (C ₁ -C ₈ ) alkyl esters; α,β-ethylenically unsaturated sulfonic acids such as styrene sulfonic acid. These can be used alone or in combination of two or more. In addition, the "monoester of polyalkylene glycol and acrylic acid or methacrylic acid" that can be used as component (b) usually has a molecular weight of 40
~500, preferably 80-400 divalent OH of polyethylene glycol or polypropylene glycol
are esterified with acrylic acid or methacrylic acid. This monoesterified product may be used alone as component (b), or may be used in combination with the above α,β-ethylenically unsaturated acid. Furthermore, "other radically polymerizable unsaturated monomers" (c) that can be radically copolymerized with the above-mentioned monomer components (a) and (b) include radically polymerizable ethylenically unsaturated bonds (C There are no particular restrictions as long as it has =C), but since polymerization is not inhibited by unsaturated groups capable of graft polymerization such as allyl groups, polymers with a Q value of 0.1 or more in the above-mentioned "Qe theory" A wide range of monomers can be selected depending on the desired performance of the final aqueous emulsion composition. Representative examples of such unsaturated monomers are as follows. (a) Esters of acrylic acid or methacrylic acid: for example, methyl acrylate, ethyl acrylate,
Propyl acrylate, isopropyl acrylate, butyl acrylate, hexyl acrylate,
Acrylics such as octyl acrylate, lauryl acrylate, cyclohexyl acrylate, methyl methacrylate, ethyl methacrylate, propyl methacrylate, isopropyl methacrylate, butyl methacrylate, hexyl methacrylate, octyl methacrylate, lauryl methacrylate, cyclohexyl methacrylate, etc. C _1-18 alkyl or cycloalkyl esters of acid or methacrylic acid; monoesters of acrylic acid or methacrylic acid and polypropylene glycol, such as polypropylene glycol monoacrylate, polypropylene glycol monomethacrylate; glycidyl acrylate, glycidyl methacrylate; glycidyl acrylate or glycidyl methacrylate and adducts with _C2-18 aliphatic monocarboxylic acid compounds (e.g. acetic acid, propionic acid, oleic acid, stearic acid, lauric acid, etc.). (b) Vinyl aromatic compounds: for example, styrene, a
-Methylstyrene, vinyltoluene, p-chlorostyrene, vinylpyridine. (c) Polyolefin compounds: for example, butadiene, isoprene, chloroprene. (d) Amides of acrylic acid or methacrylic acid: for example acrylamide, N-methylolacrylamide, N-butoxymethylacrylamide. (e) Others: Acrylonitrile, methacrylonitrile, etc. These unsaturated monomers are appropriately selected depending on the desired physical properties, and may be used alone or in combination of two or more. The copolymerization of the monomer components (a), (b) and (c) described above is as follows:
The acrylic copolymer can be produced according to a method known per se, such as a solution polymerization method, an emulsion polymerization method, a suspension polymerization method, etc.
Advantageously, the polymerization is carried out according to a solution polymerization method, in which the above three components are mixed in a suitable inert solvent in the presence of a polymerization catalyst, usually at about 0 to about 180°C, preferably at about 40 to about 170°C. At a reaction temperature of about 0.5 to about
This can be carried out by continuing the reaction for 20 hours, preferably about 2 to about 10 hours. As the solvent used, it is desirable to use a solvent that can dissolve the copolymer to be produced and is miscible with water so that gelation does not occur during the copolymerization reaction. Examples of such solvents include cellosolve solvents, carbitol solvents, glyme solvents, cellosolve acetate solvents, and alcohol solvents. Further, as the polymerization catalyst, used are conventional radical initiators for radical polymerization, such as azo compounds, peroxide compounds, sulfides, sulfines, diazo compounds, nitroso compounds, and redox compounds. When performing copolymerization, the blending ratio of the above three components can be changed depending on the desired performance of the final product aqueous emulsion composition, but based on the total weight of the above three components, the blending ratio is as follows: It is appropriate to do so. Monomer component (a): 0.1 to 30% by weight, preferably 0.5
~10% by weight Monomer component (b): When α,β-ethylenically unsaturated acid is used: 2~60% by weight, preferably 5~
30% by weight, when a monoester of polyalkylene glycol and acrylic acid or methacrylic acid is used: 10 to 80% by weight, preferably 20 to 50% by weight When both are used together, the above monoester The amount of the compound used may be 10% by weight or less. Monomer (c): 10-97.9% by weight, preferably 50-90%
weight%. The number average molecular weight of the water-soluble resin thus obtained is
It is suitable that it is in the range of 500 to 100,000, preferably 800 to 20,000. Also, the acid value is generally 10~
350, preferably in the range 30-200. The water-soluble resin can be made water-soluble by a conventional method, for example, by neutralizing the carboxyl group or sulfone group present in the resin with a conventionally known neutralizing agent (for example, amine, ammonia, alkali metal hydroxide, etc.). This can be done by Note that when a monoester of polyethylene glycol and acrylic acid or methacrylic acid is used as the monomer component (b) constituting the water-soluble resin, water solubility is generally achieved as is. Of course, water solubility by neutralization of carboxyl groups or sulfone groups may also be used in combination. According to the present invention, the above-mentioned water-soluble resin is used as a dispersion stabilizer, and the radically polymerizable unsaturated monomer is emulsion polymerized in an aqueous medium in the presence of the water-soluble resin. Such radically polymerizable unsaturated monomers are not particularly limited as long as they are compatible with the water-soluble resin and have not as strong hydrophilicity as shown above.
Representative examples are as follows. (i) Vinyl aromatic compounds: For example, _C8-10 vinylbenzene derivatives such as styrene, a-methylstyrene, vinyltoluene; vinyl heteroaromatic compounds such as vinylpyridine. (ii) Esters of acrylic or methacrylic acid: for example, methyl acrylate, ethyl acrylate, propyl acrylate, isopropyl acrylate, butyl acrylate, hexyl acrylate, lauryl acrylate, cyclohexyl acrylate, methyl methacrylate, methacrylate. C _1-20 alkyl or cycloalkyl ester of acrylic acid or methacrylic acid such as ethyl acid, propyl methacrylate, isopropyl methacrylate, butyl methacrylate, hexyl methacrylate, octyl methacrylate, lauryl methacrylate, cyclohexyl methacrylate; glycidyl acrylate or glycidyl Methacrylate and C2 _~18
Adducts with monocarboxylic acid compounds (e.g. acetic acid, propionic acid, oleic acid, stearic acid, lauric acid, etc.): methoxybutyl acrylate, methoxyethyl acrylate, ethoxybutyl acrylate, methoxybutyl methacrylate,
Alkoxy esters of acrylic acid or methacrylic acid such as methoxyethyl methacrylate and ethoxybutyl methacrylate; allyl acrylate;
Alkenyl esters of acrylic acid or methacrylic acid such as allyl methacrylate; C _2-8 hydroxyalkyl esters of acrylic acid or methacrylic acid such as hydroxyethyl acrylate, hydroxyethyl methacrylate, hydroxypropyl methacrylate and the above C _2-26 monocarboxylic acid compounds; condensate of (iii) Polyolefins having 2 to 8 carbon atoms such as butadiene, isoprene, chloroprene and the like. (iv) Vinyl carboxylate esters such as vinyl acetate and Beoba monomer (manufactured by Ciel Chemical Co., Ltd.). (v) Others: N-n-butoxyacrylamide,
Vinyl chloride, vinylidene chloride, monoolefins (such as ethylene, propylene, isobutene, etc.), etc. Among these radically polymerizable unsaturated monomers, particularly preferred in the present invention include vinyl aromatic compounds and esters of acrylic acid or methacrylic acid. These unsaturated monomers are appropriately selected depending on the physical properties desired for the final emulsion composition, and may be used alone or in combination of two or more. Furthermore, a hydrophilic unsaturated monomer may be present in the above monomers in an amount of 50% by weight or less, preferably 30% by weight or less of the total amount of monomers used. Examples of hydrophilic unsaturated monomers that may be present include 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl acrylate,
2-hydroxypropyl methacrylate, acrylonitrile, methacrylonitrile, acrylic acid,
Examples include methacrylic acid, glycidyl acrylate, glycidyl methacrylate, acrylamide, N-methylolacrylamide, and methacrylamide, and two or more of these can be used in combination. Generally known methods are used for emulsion polymerization of the radically polymerizable unsaturated monomer in the presence of the water-soluble resin. For example, the reaction is carried out in the presence of the water-soluble resin described above, using the polymerization initiator described above if necessary, with stirring or in a stationary state at a temperature above the freezing point and below the boiling point of water. As the aqueous medium as reaction medium for the above polymerizations, in addition to water, it is also possible to use mixtures of water and the previously mentioned water-miscible organic solvents. Here, the amount of water-soluble resin used as a dispersion stabilizer is generally 5 to 80% by weight based on the total solid content (total of water-soluble resin and radically polymerizable unsaturated monomer) in the emulsion to be produced. %,Preferably
The proportion may be 10 to 40% by weight. The aqueous emulsion composition thus obtained is
It can be used as it is in coating compositions as a film-forming component, and can also be used as a component in adhesives. In addition, the emulsion composition may contain other water-soluble resins, extender pigments,
Coloring pigments, rust agents, plasticizers, organic solvents, etc. can also be included in commonly used amounts. In the aqueous emulsion composition of the present invention, the water-soluble resin used as a dispersion stabilizer undergoes a moderate graft reaction with a radically polymerizable unsaturated monomer during emulsion polymerization, and the grafted product forms a well-formed polymer emulsion particle. Because they are intertwined, they exhibit excellent dispersion stability. Further, the film formed from the aqueous emulsion composition has excellent properties such as water resistance, yellowing resistance, and gloss, and does not exhibit a sticky feeling.
Moreover, even when used as a component of an adhesive, it does not stain the surface of the adhesive to which it is applied. The aqueous emulsion composition of the present invention can be used as a general paint as it is or in combination with other water-soluble or water-dispersible resins. The formed film is sufficiently cured even at room temperature, but may be cured by heating if necessary. Furthermore, the aqueous emulsion composition of the present invention can be used not only for paints but also for adhesives and resin processing. Next, the present invention will be further explained by examples.
In the examples, "%" indicates "% by weight" unless otherwise specified. Example 1 Into the 2 four-necked flask, add butyl cellosolve.
Add 556g and heat to 60℃. This stuff includes 15g of allyl methacrylate and 77g of ethyl acrylate.
g, methyl methacrylate 173g, acrylic acid 90g
g, a mixture of 201 g of 2-ethylhexyl methacrylate and 32 g of azobisdimethylvaleronitrile, and from a separate mouth a mixture of 5 g of t-dodecyl mercaptan and 50 g of butyl cellosolve at the same time.
Drip over time. One hour after the completion of the dropwise addition, 5 g of azobisdimethylvaleronitrile was added, and the mixture was left to stand for an additional 2 hours. In this way, a water-soluble resin solution with an acid value of 130 and a solid content of 48.4% was obtained. 165g of the above resin solution, ammonia water (29%) 12
cc, n-butyl methacrylate 207g and water 355g
After mixing and dispersing well, ammonium persulfate
Add a solution of 0.5g dissolved in 5g of water and heat at 80℃ for 3 minutes.
Heat for an hour. The properties and coating performance of the emulsion composition thus obtained are shown in Table 1 below. Example 2 Into the 2 four-necked flask, add butyl cellosolve.
Add 556g and heat to 60℃. This stuff includes 5g of allyl methacrylate and 77g of ethyl acrylate.
g, methyl methacrylate 173g, acrylic acid 90g
A mixed solution of 211 g of 2-ethylhexyl methacrylate and 32 g of azobisdimethylvaleronitrile was added dropwise over 3 hours. One hour after the completion of the dropwise addition, 5 g of azobisdimethylvaleronitrile was added, and the reaction was continued for an additional 2 hours. Thus, the acid value
118 and a water-soluble resin solution with a solid content of 50.5% was obtained. 158g of the above resin solution, ammonia water (29%) 11
cc, n-butyl methacrylate 207g and water 355g
After mixing and dispersing well, ammonium persulfate
Add a solution of 0.5g dissolved in 5g of water and heat at 80℃ for 3 minutes.
Heat for an hour. The properties and coating performance of the emulsion composition thus obtained are shown in Table 1 below. Comparative Example 1 A water-soluble resin was synthesized in the same manner as in Example 2, except that 5 g of allyl methacrylate in Example 2 was replaced with the same amount of 2-ethylhexyl methacrylate. The acid value of the water-soluble resin solution is 124,
The solid content was 50.3%. An emulsion composition was synthesized in the same manner as in Example 2 using the above resin solution. The properties and coating performance of the emulsion composition are shown in Table 1 below. Implementation 3 n-butyl methacrylate in Example 1
An emulsion composition was synthesized in the same manner as in Example 1 except that 104 g of n-butyl acrylate and 103 g of styrene were used instead of 207 g.
The properties and coating performance of the emulsion composition are shown in Table 2 below. Comparative example 2 n-butyl methacrylate in comparative example 1
An emulsion composition was synthesized in the same manner as in Comparative Example 1 except that 104 g of n-butyl acrylate and 103 g of styrene were used instead of 207 g. The properties and coating performance of the emulsion composition are shown in Table 2 below. Example 4 A water-soluble resin was synthesized in the same manner as in Example 1, except that the same amount of i-butyl methacrylate was used instead of the total amount of 250 g of ethyl acrylate and methyl methacrylate in Example 1. The water-soluble resin had an acid value of 129 and a solid content of 48.0%. An emulsion composition was synthesized in the same manner as in Example 1 using the above resin solution. The properties and coating performance of the emulsion composition are shown in Table 2 below. Example 5 A water-soluble resin was synthesized in the same manner as in Example 1, except that the same amount of allyl glycidyl ether and acrylic acid adduct was used in place of 15 g of allyl methacrylate in Example 1. The water-soluble resin had an acid value of 130 and a solid content of 48.1%. An emulsion composition was synthesized in the same manner as in Example 1 using the above resin solution. The properties and coating performance of the emulsion composition are shown in Table 2 below.

【table】

【table】

Claims (1)

[Claims] 1 (a) The following formula in one molecule: [Wherein, R represents a hydrogen atom or a methyl group, R′ represents a [formula] [formula] phenylene or a lower alkenylene group, R'' represents a hydrogen atom,
a monomer containing one radically polymerizable unsaturated group and at least one graft polymerizable unsaturated group, (b) α,β-ethylenically unsaturated group; At least 1 in the presence of a water-soluble resin consisting of a saturated acid and/or a monoester of polyalkylene glycol and acrylic acid or methacrylic acid, and (c) a copolymer of another radically polymerizable unsaturated monomer. 1. A method for producing an aqueous emulsion composition, comprising emulsion polymerization of various radically polymerizable unsaturated monomers.