JPH0416487B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for producing an aqueous dispersion type resin composition having good coating performance. In recent years, in the field of paints and adhesives, attempts have been made to switch from using organic solvents to water-soluble or water-dispersible resins from the viewpoint of pollution control or resource conservation. However, conventional aqueous dispersion resins have been manufactured by emulsion polymerization using ionic or ionic surfactants, and as a result, the coating film formed is affected by the surfactant used in polymerization. They had the disadvantage that they had poor water resistance and stain resistance, and that the gloss of the coating was inferior to that of solvent-based coatings due to the difference in the film-forming mechanism. Various attempts have been proposed to improve this drawback, and one of them is to use a water-soluble polymer compound such as maleated polybutadiene, maleated alkyd resin, water-soluble acrylic resin, etc. as a dispersion stabilizer. There is a method of performing a polymerization reaction in a medium to obtain the desired aqueous dispersion type resin. According to this method, the particle size of the aqueous dispersion type resin produced is 0.1μ or less, approximately 0.02 to 0.05μ, compared to the particle size obtained by conventional emulsion polymerization method, which is 0.1μ or less.
It is possible to obtain a much finer film than that of ~0.3μ, and the gloss of the formed film is also close to that of a solvent-based film. In addition, since the polymerization dispersion stabilizer is a polymer compound and has strong interactions such as graft bonding with the resin produced during polymerization, it is also recognized to have an improvement effect in terms of water resistance and stain resistance. However, while having the above-mentioned advantages, resins using maleated polybutadiene or maleated alkyd resin as dispersion stabilizers exhibit unique aqueous solution behavior in terms of physical properties, and in practical terms, have poor coating workability and storage stability. It is said that it has drawbacks and its use is limited to a very limited range. In addition, when polymerizing water-soluble acrylic resin as a dispersion stabilizer,
Since the protective power of the particles depends on the affinity between the dispersion resin and the resulting polymer, it has the disadvantage of poor polymerization stability.To overcome this disadvantage, unsaturated groups were introduced into the side chains of water-soluble acrylic resin. Therefore, it is necessary to devise ways to increase polymerization stability by graft polymerization. In addition, not only maleated polybutadiene and maleated alkyd resin, but also water-soluble acrylic resin,
It has a carboxyl group in its molecular structure, and the conventional method is to make it water-soluble by neutralizing it with a basic substance such as triethylamine or ammonia. Therefore, it has the following drawbacks. First, since amines and ammonia are used as neutralizing agents, sufficient odor control measures are required during production, and it is inevitable that the final product will have a unique unpleasant odor. Second, when polymerizing a water-soluble resin as a dispersion stabilizer, the amount of emulsifier used is larger than that used in normal emulsion polymerization, so the proportion of carboxyl groups in the resulting water-dispersed resin composition is high. As a result, the water resistance of the coating film decreases.
Furthermore, the presence of carboxyl groups tends to cause the coating film to become rigid, resulting in a decrease in adhesion and impact resistance. The present inventors have conducted extensive research on water-soluble resin compositions and manufacturing methods that enable stable polymerization and have good quality characteristics in aqueous dispersion polymerization using a water-soluble resin as a dispersion stabilizer. α,β-ethylenically unsaturated monomer having the general formula (1) [However, R ₁ is a hydrogen atom or a methyl group, R ₂ is -CO-O (-CH ₂ -) _o (n = 1 to 4), phenylene,
R ₃ and R ₄ represent a methyl group or an ethyl group] α, β-ethylenically unsaturated monomer represented by (2) allyl (meth)acrylate, (3) alkyl (meth)acrylate, the above (1) ), (2), and (3), the resulting copolymer is neutralized with acid to make it water-solubilized, and then, in the aqueous solution, (4) styrene, acrylonitrile, and alkyl (meth) The present inventors have discovered that the desired object can be achieved by adding at least one radically polymerizable unsaturated monomer selected from the group consisting of acrylates and carrying out aqueous dispersion polymerization, and have accomplished the present invention. That is, the present invention improves polymerization stability by converting a conventionally anionic water-soluble resin into a cationic resin and introducing a graftable side chain into the water-soluble resin.
The present invention provides a method for producing a water-soluble resin composition for aqueous dispersion polymerization that has good quality characteristics. below,
The present invention will be explained in detail. The water-soluble resins used in the present invention include (1) to
It can be obtained by copolymerizing the monomer (3) and neutralizing it with acid. The amounts of (1) to (3) used are as shown below, when the total of (1), (2), and (3) is 100 parts by weight. (1) 10 to 50 parts by weight of the α,β-ethylenically unsaturated monomer having a tertiary amino group, preferably
15-40 parts by weight (2) Allyl (meth)acrylate having at least two or more unsaturated groups with different polymerizability in one molecule
0.1 to 5 parts by weight, preferably 0.2 to 3 parts by weight (3) 89.9 to 45 parts by weight, preferably 84.8 parts to 55 parts by weight of alkyl (meth)acrylate copolymerizable with (1), (2) Examples of compounds represented by body (1) are:
Compounds in which R ₂ is -CO-O(-CH ₂ -) _o (n = 1 to 4), such as acrylic acid such as dimethylaminoethyl (meth)acrylate and diethylaminoethyl (meth)acrylate, amino acids of methacrylic acid Alkyl esters and compounds where R ₂ is phenylene or lower alkenylene, such as p-dimethylaminostyrene, 1-dimethylamino-4
- Examples include vinylnaphthalene. These compounds are essential for imparting water solubility to the copolymer, and the amount used is determined from the following viewpoint. The first is that the copolymer is soluble in water, the second is that it can be used as a dispersion stabilizer for polymerization, and the third is that the final product, the water-dispersed resin, is of good quality. There are three points. From the point of view of solubility in water, a minimum of 10 parts by weight is required in the copolymer, and the more it is, the more hydrophilic it becomes. It is necessary to strike a balance, and from the viewpoint of the quality of the final product, an increase in the number of hydrophilic groups is undesirable because it is accompanied by deterioration in water resistance. Taking these into consideration, the monomer (1) is preferably 10 to 50 parts by weight,
More preferably, 15 to 40 parts by weight are used. Specific examples of compounds used for monomer (2) include allyl (meth)acrylate, esterified products of (meth)acrylic acid and ethylene glycol monoallyl ether, and adducts of (meth)acrylic acid and allyl glycidyl ether. etc. These compounds provide active sites that can perform graft polymerization during aqueous dispersion polymerization, and stabilize polymerization through chemical bonding between the water-soluble resin and the main polymer (polymer of monomer (4)). However, if the amount used is less than 0.1 parts by weight, the effect will be small, and if it is more than 5 parts by weight, a crosslinking reaction will occur, causing problems such as difficulty in making the polymer water-soluble. 3
Parts by weight are used. As specific examples of the compound used for monomer (3), the following unsaturated monomers such as esters of acrylic acid or methacrylic acid are used. For example, C ₁ to _{C 18} aliphatic alcohols such as methyl (meth)acrylate, ethyl (meth)acrylate, butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, lauryl (meth)acrylate, and stearyl (meth)acrylate. Esters of acrylic acid, methacrylic acid, also alkoxyalkyl esters of acrylic acid or methacrylic acid, such as methoxybutyl (meth)acrylate, methoxyethyl (meth)acrylate, ethoxybutyl (meth)acrylate, and also, for example, hydroxyethyl (meth)acrylate Acrylate, hydroxyalkyl ester of acrylic acid or methacrylic acid such as hydroxypropyl (meth)acrylate, or polyethylene glycol of acrylic acid or methacrylic acid, polypropylene glycol such as polyethylene glycol mono(meth)acrylate, polypropylene glycol mono(meth)acrylate. These unsaturated monomers may be selected as desired and may be used alone or in combination of two or more types, but preferably an aqueous dispersion. The stability during aqueous dispersion polymerization can be increased by selecting monomers that are similar in molecular structure to the monomers used. Further, if the amount is outside the range of 45 to 89.9 parts by weight, thickening and generation of foreign matter may occur, which is not preferable in terms of polymerization stability. Copolymerization of the above monomers can be carried out by any of the commonly used polymerization methods, such as emulsion polymerization, suspension polymerization, and solution polymerization. For convenience, solution polymerization is preferably used. When carrying out solution polymerization, the solvent used is:
Any solvent that can dissolve the copolymerization reaction product can be used, but when the polymer is dissolved in an aqueous medium and used as a dispersion stabilizer for polymerization, there is no need to recover the solvent. Preference is given to using water-soluble organic solvents. Such solvents include (a) alcoholic solvents represented by R ₁ OH (R ₁ represents a lower alkyl group such as methyl group, ethyl group, n-propyl group, iso-propyl group) (b) HO-CH Ethylene glycol monoalkyl ether represented by ₂ -CH ₂ -OR ₂ (R ₂ is a methyl group, ethyl group, n-propyl group, iso-propyl group, n-butyl group, sec-butyl group, t-
(3) Diethylene glycol monoalkyl ether represented by HO-CH ₂ -CH ₂ -O-CH ₂ -CH ₂ -OR ₃ (R ₃ is a methyl group, ethyl group, n-butyl group, etc.) (d) Ethylene glycol ether esters represented by R ₄ CO-O-CH ₂ -CH ₂ -OR ₅ (R ₄ is a methyl group, ethyl group, etc., R ₅ is a methyl group, ethyl group, etc.) , butyl group, etc.) can be used. As the polymerization initiator, azo-based initiators such as azobisisobutyronitrile and azobisdimethylvaleronitrile are usually recommended. Peroxide-based initiators such as benzoyl peroxide and lauroyl peroxide decompose ionically when tertiary amino groups are present in the system, so it is necessary to be careful in how they are used. Regarding the polymerization conditions, a polymerization temperature of usually 40 to 170°C, preferably 50 to 130°C and a polymerization time of 4 to 20 hours is preferred. When carrying out aqueous dispersion polymerization using the copolymer thus obtained, it is first necessary to dissolve the polymer in an aqueous medium. Note that the aqueous medium herein means water or water in which a water-soluble organic solvent is dissolved. Water solubilization can be achieved by neutralizing the amino groups in the copolymer with an inorganic acid such as hydrochloric acid, phosphoric acid, nitric acid, or sulfuric acid, or an organic acid such as formic acid or acetic acid. The amount of acid used for neutralization does not need to be more than an equivalent amount, and it is generally sufficient that the total amount of monomers having amino groups to be neutralized exceeds 10 parts by weight of the copolymer. Of course, there is no problem in using an equivalent or more amount of acid to adjust the pH during polymerization. The pH during polymerization is determined by considering the polymerization rate, polymerization stability, corrosion resistance of the polymerization container, etc.
It is preferable to carry out polymerization by adjusting the ratio between 2.0 and 5.5. In addition, when making the copolymer water-soluble, the copolymer may be mixed with an aqueous medium while being dissolved in a water-soluble organic solvent, or the copolymer may be recovered by a method such as distillation or reprecipitation and then added to an aqueous medium. You can add it. Using the thus obtained copolymer as a dispersion stabilizer, a polymerization reaction is carried out in an aqueous medium to obtain the desired aqueous dispersion type resin composition. Regarding the polymerization operation, a normal emulsion polymerization operation can be adopted. Monomers that can be used during aqueous dispersion polymerization include:
Alkyl (meth)acrylates shown in the following 1) to 4), styrene, acrylonitrile, and other radically polymerizable unsaturated monomers copolymerizable with these may be used. 1 Acrylic acid or methacrylic acid ester 2 Aromatic vinyl compound 3 Other monomers that can be copolymerized with 1) and 2), but in addition to these 4 For example, polyethylene glycol dimethacrylate, ethylene glycol diacrylate, triallyl cyanurate It is also possible to use a monomer having two or more polymerizable unsaturated bonds, such as , to make the resulting polymer have a crosslinked structure. One or more of these monomers can be appropriately selected depending on the quality requirements of the final product. The amount of water-soluble resin used as a dispersion stabilizer is 2/1 to 1/10 by weight of the monomer to be polymerized.
It is. Outside this range, thickening and generation of foreign matter may occur, which is unfavorable in terms of polymerization stability. Water is usually used as the aqueous medium for dissolving the dispersion stabilizer, but if the dispersant resin is used dissolved in an organic solvent, the result is that the system contains an amount of organic solvent commensurate with the amount of the dispersant resin. It will be.
In addition, for the purpose of increasing the solubility of the dispersant resin, it is also possible to add a water-soluble organic solvent in an amount of 1/2 or less of the amount of water. As a polymerization initiator, it is usually used in radical polymerization. Although water-soluble and oil-soluble peroxides, azo initiators, redox initiators, and the like can all be used, water-soluble initiators are preferably used.
It is also possible to use ionic and nonionic surfactants that are normally used in emulsion polymerization.
From the viewpoint of water resistance, it is preferable to use only a small amount. The polymerization conditions are a polymerization temperature of 30 to 90°C, preferably 40 to 90°C.
It can be carried out within a range of 80°C. The solid content concentration in the water-dispersed resin composition is in the range of 20% by weight to 60% by weight when using the method of the present invention. When the solid content concentration exceeds 60% by weight, the viscosity of the system increases significantly, making it difficult to remove the heat generated by the polymerization reaction, and causing inconveniences such as a long time required to remove the polymer from the polymerization machine. . In addition, if the solid content concentration is 20% by weight or less, although there will be no problem in the polymerization operation, the amount of resin produced in one polymerization operation will be small, which will be extremely disadvantageous from an economic standpoint. Also, from the requirements of the application, if the concentration is less than 20% by weight, the thickness of the coating film will become thinner, resulting in deterioration of performance. The aqueous dispersion resin composition thus obtained is composed of ultrafine particles with a particle size of 0.02 to 0.1 μm, and as a result has excellent film-forming ability. The present invention will be explained below with reference to Examples. Example 1 800 g of butyl cellosolve is added to a 2 L four-necked glass flask equipped with a stirrer, dropping funnel, reflux condenser, and thermometer, and heated to 70° C. in a nitrogen stream. When the internal temperature reached 70°C, 544 g of methyl methacrylate, 240 g of 2-dimethylaminoethyl methacrylate, 16 g of allyl methacrylate,
A mixed solution of 16 g of azobisdimethylvaleronitrile was added dropwise over 3 hours. After the dropwise addition was completed, 4 g of azobisdimethylvaleronitrile was added and the reaction was continued for an additional 2 hours. A resin solution with a solids content of 50% was thus obtained. Next, add 380 g of the above resin solution, 400 g of 1N hydrochloric acid, and 500 g of deionized water to a glass 2L 4-necked flask equipped with a stirrer, addition funnel, reflux condenser, and thermometer, and stir and mix well to dissolve the resin. . Furthermore, 1 g of ammonium persulfate is added, dissolved, and then the temperature is raised until the internal temperature reaches 70°C. After reaching 70℃, 270g of methyl methacrylate, butyl acrylate
50 g of the mixture was added dropwise over 3 hours. After dropping, heat for another 2 hours until the solid content is 30% and the particle size is approx.
A water-dispersed resin composition with a pH of 3.8 at 0.04μ was obtained. Example 2 800 g of ethanol was placed in a 2L 4-necked glass flask equipped with a stirrer, dropping funnel, reflux condenser, and thermometer.
and heat to 65°C in a nitrogen stream. Internal temperature is 70
When it reaches 320 °C, methyl methacrylate
A mixed solution of 256 g of butyl methacrylate, 200 g of 2-dimethylaminoethyl methacrylate, 24 g of allyl methacrylate, and 16 g of azobisdimethylvaleronitrile was added dropwise over 3 hours. After the addition was completed, the reaction was continued for another 2 hours. Thus solids content 50
% resin solution was obtained. Next, 200 g of the above resin solution, 180 g of 1N hydrochloric acid, 720 g of deionized water, and sodium formaldehyde sulfoxylate were placed in a 2L 4-neck glass flask equipped with a stirrer, addition funnel, reflux condenser, and thermometer.
Add 1.0 g of ferrous sulfate and 0.005 g of ferrous sulfate, stir thoroughly to dissolve, and then raise the temperature until the internal temperature reaches 60°C. After reaching 60°C, a mixed solution of 280 g of styrene, 40 g of acrylonitrile, 30 g of butyl acrylate, 20 g of methyl methacrylate, and 1 g of cumene hydroperoxide was added dropwise over 6 hours. In this way, a water-dispersed resin composition with a solid content of 35% and a pH of 3.5 was obtained. The particle size of this composition was approximately 0.05μ. Example 3 A 50% ethanol solution of the resin obtained in Example 2 was dropped into water, and the precipitated polymer was separately dried to obtain a resin powder. Next, 100 g of the above resin powder, 180 g of 1N hydrochloric acid, 820 g of deionized water, 1.0 g of ascorbic acid, and 0.005 g of ferrous sulfate were placed in a 2L 4-neck glass flask equipped with a stirrer, dropping funnel, reflux condenser, and thermometer. In addition,
After sufficiently stirring to dissolve, raise the temperature until the internal temperature reaches 60°C. After reaching 60° C., a mixed solution of 160 g of methyl methacrylate, 160 g of butyl methacrylate, 6 g of polyethylene glycol dimethacrylate, and 1 g of yumene hydroperoxide was added dropwise over 4 hours. Thus, the solids concentration is 35%,
An aqueous dispersion composition with a particle size of approximately 0.05μ and a pH of 3.0 was obtained. Application Example 1 The coating film performance of the aqueous dispersion type resins obtained in Examples 1 to 3 was evaluated by surface coating (for polishing) of paper. A solution type paper gloss varnish with the following composition was selected as a control sample for comparison. The composition of the solution type paper gloss varnish is as follows. A Styrene/methyl methacrylate/acrylonitrile = 65/25/10 (weight ratio) Solvent Ethyl acetate solid content concentration 47.8% by weight B Vinyl chloride/vinyl acetate = 72/28 (weight ratio) Solvent Ethyl acetate solid content concentration 50% by weight A and B were mixed so that the solid content ratio was A/B = 7/3, and further diluted with toluene so that the solid content concentration was 25% by weight to obtain a solution type paper gloss varnish. Coating for paper polishing and evaluation were carried out in the following manner. Coating paint solids content
25% by weight (water-based dispersion resin is diluted with water) Coater Bar coater #10 Drying 105℃ x 10 seconds Press conditions 120℃ x 250Kg/cm ² x 20m/min Coating film evaluation

【table】 The evaluation results are shown in Table 1.

[Table] Example 4 800 g of ethyl cellosolve acetate was added to a 2L 4-necked glass flask equipped with a stirrer, dropping funnel, reflux condenser, and thermometer, and the mixture was heated to 780 g in a nitrogen stream.
Heat to ℃. When the internal temperature reaches 80℃, 640g of methyl methacrylate and butyl acrylate are added.
64g, diethylaminoethyl methacrylate 120
A mixed solution of 160 g of allyl acrylate and 8 g of azobisisobutyronitrile was added dropwise over 4 hours. After the dropwise addition was completed, 2 g of azobisisobutyronitrile was added and the reaction was continued for an additional 2 hours. A resin solution with a solids content of 50% was thus obtained. Next, add 400 g of the above resin solution, 160 g of 1N acetic acid, and 840 g of deionized water to a glass 2L 4-necked flask equipped with a stirrer, addition funnel, reflux condenser, and thermometer, and stir and mix well to dissolve the resin. . Furthermore, 1 g of potassium persulfate was added and dissolved, and the temperature was then raised until the internal temperature reached 70°C. After reaching 70°C, a mixed solution of 300 g of methyl methacrylate and 300 g of butyl methacrylate was added dropwise over 4 hours. After the addition was completed, heating was continued for 2 hours to obtain an aqueous dispersion resin composition with a solid content of 40%, a particle size of approximately 0.08 μm, and a pH of 3.2. Example 5 800 g of butyl cellosolve is added to a 2L 4-neck glass flask equipped with a stirrer, dropping funnel, reflux condenser, and thermometer, and heated to 75° C. in a nitrogen stream.
When the internal temperature reached 74°C, a mixed solution of 320 g of methyl methacrylate, 144 g of butyl methacrylate, 320 g of dimethylaminoethyl methacrylate, 2 g of allyl methacrylate, and 16 g of azobisdimethylvaleronitrile was added dropwise over 6 hours. After the addition is complete, heating is continued for another 2 hours. A resin solution with a solids content of 50% was thus obtained. Next, 160 g of the above resin solution, 480 g of 1N hydrochloric acid, 340 g of deionized water, and sodium formaldehyde sulfoxylate were placed in a 2L 4-neck glass flask equipped with a stirrer, a dropping funnel, a reflux condenser, and a thermometer.
Add 1.0 g of ferrous sulfate and 0.02 g of ferrous sulfate, stir thoroughly to dissolve, and then raise the temperature until the internal temperature reaches 60°C.
After reaching 60°C, a mixed solution of 560 g of methyl methacrylate, 240 g of butyl acrylate, and 3 g of cumene hydroperoxide was added dropwise over 6 hours. In this way, a water-dispersed resin composition with a solid content of 50% and a pH of 4.0 was obtained. The particle size of this composition is approximately
It was 0.07μ. Application Example 2 The coating film performance of the aqueous dispersion type resins obtained in Examples 4 and 5 was evaluated by coating the surface of paper (for polishing) in the same manner as in Application Example 1 above. The evaluation results are shown in Table 2.

【table】

Claims (1)

[Claims] 1 The following general formula (1) [However, R ₁ is a hydrogen atom or a methyl group, R ₂ is -CO-O (-CH ₂ -) _o (n = 1 to 4), phenylene,
R ₃ and R ₄ represent a methyl group or an ethyl group] α, β-ethylenically unsaturated monomer represented by (2) allyl (meth)acrylate, (3) alkyl (meth)acrylate, the above (1) ), (2), and (3) in weight ratio (1)/(2)/(3)=
A monomer mixture of 10/0.1/89.9 to 50/5/45 is copolymerized, the resulting copolymer is neutralized with acid to make it water-solubilized, and then in the aqueous solution, (4) styrene, acrylonitrile and at least one radically polymerizable unsaturated monomer selected from the group consisting of alkyl (meth)acrylate, and the weight ratio of (1) + (2) + (3) and (4) is (1) ＋(2)＋
A method for producing an aqueous dispersion type resin composition, characterized by carrying out aqueous dispersion polymerization at a ratio of (3)/(4)=2/1 to 1/10. 2. The aqueous dispersion type resin according to claim 1, wherein the copolymer consisting of monomers (1), (2), and (3) is polymerized in an organic solvent that can dissolve the copolymer. Method of manufacturing the composition.