JP2687343B2 - Method for producing aqueous dispersion - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to the production of a stable high molecular weight polyurethane-based aqueous dispersion having excellent film performance, particularly elasticity, toughness, strength and the like. [Prior Art] Synthetic resin-based and rubber-based emulsions have been
Paper impregnation, paper coating paint, carpet paint, sealant,
Cement mortar, adhesives, adhesives, floor polishes, water-based varnishes, water-based inks, leather treatments, metal, plastic and wood top coats are used in a wide variety of applications. As a proposal for improving the elasticity of coating films of such synthetic resin-based and rubber-based emulsions, JP-A-53-5123 has been proposed.
There are JP-A No. 2 and JP-A No. 59-13821. However, although these films have excellent elasticity of the coating film, it is difficult to obtain a polymer having a high molecular weight, so that there is a problem that a film having excellent toughness and strength cannot be obtained. [Problems to be Solved by the Invention] As a result of intensive studies to solve the above problems, the present inventor has found that a coating film having excellent toughness and strength in addition to elasticity due to high molecular weight by urethane seed polymerization is obtained. It was found that a high molecular weight aqueous dispersion that can be given is obtained, and the present invention has been completed based on this finding. [Means for Solving Problems] The present invention is a method for obtaining an aqueous dispersion by copolymerizing the following monomer mixture (B) in the presence of the following polyurethane aqueous dispersion (A): A pH of the polymerization system is set to 7 or less, and the amount of (A) used is 0.01 to 2.5 parts by weight of (A) per 100 parts by weight of solid content (A). A manufacturing method is provided. Polyurethane aqueous dispersion (A): A polyurethane aqueous dispersion obtained from an aliphatic, aromatic or alicyclic polyisocyanate compound having two or more isocyanate groups, or a prepolymer having an isocyanate group at the terminal, and a polyol. Monomer mixture (B): A monomer mixture containing an α, β-unsaturated carboxylic acid, which is 0.5 to 30% by weight based on the whole monomer mixture (B). Next, each of the constituent features of the present invention will be described in detail. The aliphatic, aromatic or alicyclic polyisocyanate compound having two or more isocyanate groups and the prepolymer having an isocyanate group at the terminal used in the polyurethane aqueous dispersion (A) are as follows. For example, 1,4-tetramethylene diisocyanate, 1,
Aliphatic diisocyanates such as 6-hexamethylene diisocyanate, 2,4,4-trimethylhexamethylene diisocyanate, 2,8-diisocyanate methylcaproate, 3-isocyanate methyl-3,5,5-trimethylcyclohexyl isocyanate, dicyclohexyl Methane-
4,4'-diisocyanate, methylcyclohexyl-2,4
Alicyclic diisocyanates such as diisocyanate, toluylene diisocyanate, diphenylmethane diisocyanate, 1,5-naphthene diisocyanate, diphenylmethylmethane diisocyanate, tetraalkyldiphenylmethane diisocyanate, 4,4′-dibenzyl diisocyanate, 1,3-phenylenediisocyanate Aromatic diisocyanates, chlorinated diisocyanates, brominated diisocyanates, and / or compounds having two or more active hydrogen atoms, such as polyethylene glycol, polypropylene glycol, trimethylolpropane, glycerin,
Pentaerythritol or the like, or a polyisocyanate compound which is an adduct with water is used. Of these, aliphatic and alicyclic polyisocyanates are preferable, and aliphatic polyisocyanates are more preferable, from the viewpoint of weather resistance and the like. As the polyols to be used, for example, polyethers, polyesters, polyesteramides, polythioethers, polycarbonates and polybutadiene glycols can all be used. The polyether is, for example, a ring-opening polymer or copolymer of ethylene oxide, propylene oxide, butylene oxide, tetrahydrofuran or the like, or the above addition polymer to a compound having active hydrogen such as bisphenol, glycerin or trimethylolpropane. Polyesters include ethylene glycol, propylene glycol, 1,3-butanediol, 1,4-butanediol, neopentyl glycol, pentanediol, hexanediol, octanediol, 2-ethyl 1,3-hexanediol, bisphenol A, It is obtained by mixing a saturated or unsaturated low molecular weight glycol such as diethylene glycol and dipropylene glycol with a dibasic acid. In addition, hexamethylene glycol type, caprolactone type, polythioether type, and polyacetal type can also be used. From the viewpoint of elasticity and toughness of the coating film of the finally obtained copolymer aqueous dispersion, polyethers, polyesters and polycarbonates are preferable. The α, β-unsaturated carboxylic acid contained in the monomer mixture (B) is, for example, a monocarboxylic acid or a dicarboxylic acid such as acrylic acid, methacrylic acid, crotonic acid, maleic acid, fumaric acid, itaconic acid. Examples of the monomer other than the α, β-unsaturated carboxylic acid contained in the monomer mixture (B) include methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate, n-butyl acrylate, and methacrylic acid. Acid n-
Butyl, isobutyl acrylate, n-butyl methacrylate, isobutyl methacrylate, pentyl acrylate, pentyl methacrylate, hexyl acrylate, hexyl methacrylate, heptyl acrylate, heptyl methacrylate, 2-ethylhexyl acrylate, octyl acrylate, Octyl methacrylate, n-nonyl acrylate, isononyl acrylate, nonyl methacrylate, decyl acrylate, decyl methacrylate, undecyl acrylate,
Undecyl methacrylate, dodecyl acrylate, dodecyl methacrylate, n-amyl acrylate, isoamyl acrylate, n-amyl methacrylate, isoamyl methacrylate, lauryl acrylate, lauryl methacrylate,
(Meth) acrylic acid alkyl ester compounds such as benzyl acrylate, benzyl methacrylate, cyclohexyl acrylate, cyclohexyl methacrylate, styrene, α-methylstyrene, methylstyrene, p-methylstyrene, vinylxylene, monochlorostyrene, dichlorostyrene. , Monobromstyrene, dibromostyrene,
Aromatic vinyl compounds such as fluorostyrene, vinylnaphthalene, and ethylstyrene, vinyl cyan compounds such as acrylonitrile and methacrylonitrile, 1,3-butadiene, 2-methyl-1,3-butadiene, 2,3-dimethyl-1, 3-butadiene, 2-chloro-1,3
-Butadiene, isoprene, 2-cyano-1,3-butadiene, substituted linear conjugated pentadiene, linear and side chain conjugated hexadiene and other aliphatic conjugated diene monomers, vinyl acetate, vinyl propionate, vinyl stearate, etc. Organic acid vinyl compounds, vinyl ether compounds such as vinyl methyl ether, vinyl ethyl ether, vinyl isobutyl ether, vinyl phenyl ether, vinylidene halide compounds such as vinylidene chloride and vinylidene fluoride, and vinyl methyl ketone, vinyl pyridine, isobutylene, 1, 1-chlorofluoroethylene, Veova-10 (Ciel Chemical) and the like can be mentioned. When using these monomer compounds, they are used alone or as a mixture, but usually, several kinds of monomers are mixed and used. Depending on the intended use of the produced aqueous dispersion, it is selected from the above monomers and used, but when weather resistance, toughness of the coating film, etc. are required, (meth) acrylic acid alkyl ester Monomers, particularly when elasticity and abrasion resistance are required, aliphatic conjugated diene-based monomers, vinyl cyan monomers and aromatic vinyl monomers are preferable, and most preferable among them is 1,3-butadiene. Acrylonitrile and styrene. When importance is attached to the weather resistance and toughness of the coating film, the (meth) acrylic acid alkyl ester monomer is 20 parts by weight or more, preferably 50 parts by weight, based on 100 parts by weight of the monomer mixture (B).
It is recommended to use more than parts by weight. To further enhance the toughness and abrasion resistance of the coating film of the aqueous dispersion obtained by the present invention, divinyl ether such as divinylbenzene, allyl acrylate, divinyl ether, ethylene glycol and diethylene glycol, 1,6 -Cross-linkable monomers such as hexanediol diacrylate, neopentyl glycol, diacrylate, trimethylolpropane diacrylate, or triacrylate, acrylamide, methacrylamide, N-methylol methacrylamide, diacetone acrylamide, ethacrylamide, crotonamide, Amide-based monomers such as itacone amide, methylenediacrylamide and maleic acid monoamide, glycidyl group-containing monomers such as glycidyl acrylate and glycidyl methacrylate, acrylic acid 2-
A hydroxyl group-containing monomer such as hydroxyethyl or 2-hydroxyethyl methacrylate can be used together. A production example of the present invention will be described in order. As a production example of the polyurethane aqueous dispersion (A), a polyisocyanate and a polyol are usually reacted at 30 to 150 ° C. for several hours to ten hours to obtain a prepolymer. There is no restriction on the ratio of the polyol to the polyisocyanate, but 1.2 to 3.5 equivalents of polyisocyanate are preferable per one active hydrogen of the polyol. If necessary, for example, dimethylolpropionic acid,
It is also possible to crosslink using a chain extender such as 1,4-butylene glycol. The molecular weight of this chain extender is less than 300,
It is preferable because the finally obtained aqueous dispersion coating film has good elasticity and toughness. When thickening during the reaction, a solvent may be used if necessary. Also, a catalyst is added if necessary. After completion of the reaction, the mixture is neutralized with alkalis, amines, ammonia, etc. to obtain an aqueous dispersion. To the polyurethane aqueous dispersion obtained by the above method, water, a polymerization initiator, and if necessary, a surfactant and other auxiliaries are added to prepare a monomer mixture (B).
Is polymerized. As this method, there are generally known methods such as a batch charging method for monomers, a method for adding monomers, and an method for adding emulsion. The latter two methods are continuously or dividedly added to carry out polymerization. As the surfactant for dispersing the unsaturated compound in water at the time of polymerization, nonionic, anionic, or zwitterionic type is used. Among them, the combination of nonionic and anionic types is good, and particularly good is poly A combination of oxyethylene nonyl phenyl ether and sodium alkyl diphenyl ether disulfonate and sodium alkylbenzene sulfonate. As polymerization initiators, organic hydroperoxides represented by cumene hydroperoxide, diisopropylbenzene hydroperoxide, paramenthane hydroperoxide, etc. and sugar-containing pyrophosphate formulation, sulfoxylate formulation, sugar-containing pyrophosphate formulation / sulfo Redox type initiators in combination with reducing agents typified by mixed system formulations of xylate formulations, and further persulfates such as potassium persulfate and ammonium persulfate, azobisisobutyronitrile, benzoyl peroxide, lauroyl A peroxide or the like can be used optionally. Particularly preferably, persulfates such as potassium persulfate and ammonium persulfate, azobisisobutyronitrile and benzoyl peroxide are combined with a reducing agent if necessary. The temperature at which the polymerization is carried out is usually 5 to 95 ° C, and particularly preferably 50 to 90 ° C. What is important here is the ratio of the aqueous polyurethane dispersion (A) to the monomer mixture (B). The molecular weight of the finally obtained copolymer aqueous dispersion has a great effect on the elasticity and toughness of the coating film, but the molecular weight of the copolymer aqueous dispersion must be 400,000 or more in order to express this characteristic. Is. In order to obtain a copolymer aqueous dispersion having a molecular weight of 400,000 or more, the ratio of the polyurethane aqueous dispersion (A) to the monomer mixture (B) is 100 parts by weight of the monomer mixture (B), and the polyurethane aqueous dispersion ( A) is polymerized in the range of 0.01 to 2.5 parts by weight. When the polyurethane aqueous dispersion (A) has a solid content of less than 0.01 parts by weight, a high molecular weight copolymer aqueous dispersion can be obtained, but the film-forming property is poor, and the coating film is fragile and does not exhibit elasticity, which is not preferable. If it exceeds 2.5 parts by weight, the molecular weight is 40
I could not get more than 10,000, so the coating film has elasticity,
The toughness and strength are not obtained and the wear resistance is poor. These (A)
The ratio of / (B) is preferably 0.2 / 100 to 2.0 / 100, more preferably 0.4 / 100 to 1.5 / 100. It is important that the pH of the polymerization system of the emulsion copolymerization method of the present invention is 7 or less. If the pH exceeds 7, the reactivity with other monomers of α, β-unsaturated carboxylic acid will be poor, and therefore the stability during polymerization will be poor, and not only a large amount of coagulated matter but also the formed aqueous dispersion will be formed. The storage stability and the compounding stability are poor, and it is not worth the product. pH of polymerization system containing polyurethane aqueous dispersion of pH 7 or higher
As a method of lowering the temperature, there is a method of using an acid such as sulfuric acid or hydrochloric acid, a buffering agent such as sodium hydrogen carbonate or the like. In 100 parts by weight of the monomer mixture (B), the amount of α, β-unsaturated carboxylic acid is 0.5 to 30 parts by weight, preferably 3 to 20 parts by weight. If it is less than 0.5 part by weight, the stability at the time of polymerization is poor and not only a large amount of solidified matter but also the toughness of the coating film cannot be exhibited. or
If it exceeds 30 parts by weight, the water resistance and elasticity of the coating film will be poor. The particle diameter of the polyurethane aqueous dispersion used is not particularly limited, but is preferably 0.03 to 0.4 µ, and particularly preferably 0.04 to 0.3 µ. The aqueous dispersion thus obtained can be thickened with an aqueous alkaline solution such as sodium hydroxide or ammonia. It is also possible to increase the viscosity by using a water-soluble polymer compound such as hydroxylethyl cellulose, methyl cellulose, polyvinyl alcohol. The copolymer aqueous dispersion obtained in the present invention may further contain additives such as a plasticizer, a solvent, a coloring agent, a preservative and a fragrance, if necessary. The copolymer aqueous dispersion of the present invention thus obtained,
Fiber, paper impregnation, paint, sealant, paper coating paint, carpet, cement mortar, adhesive, adhesive, water-based varnish, water-based ink, floor polish, leather treatment, metal, plastic and wood top coat agent It can be used for various purposes. [Examples] Hereinafter, the present invention will be specifically described with reference to Examples. Unless otherwise specified, the parts shown in the following examples and comparative examples mean parts by weight. <Method for producing aqueous polyurethane dispersion (A)> The reaction vessel was sealed with nitrogen gas, 56 parts by weight of propylene glycol and 34 parts by weight of 1,6-hexamethylene diisocyanate were charged, and the temperature was raised to 80 to 85 ° C. . The reaction temperature was kept at 80 to 85 ° C and the reaction was carried out for 4 hours. 4 parts by weight of dimethylolpropionic acid and 6 parts by weight of 1,4-butylene glycol were added to 90 parts by weight of the obtained prepolymer, and a crosslinking reaction was carried out at the same temperature. Since an increase in viscosity was observed, 16 parts by weight of dioxane was added to lower the viscosity and the reaction was continued. When almost no absorption of isocyanate groups was observed in the infrared absorption spectrum (2300 Kaiser), a solution prepared by adding 3.7 parts by weight of ammonia water to 66 parts by weight of water was added,
An additional 120 parts by weight of water was added. After further aging at 85 ° C. for 1 hour, the reaction system was cooled and taken out to obtain a polyurethane aqueous dispersion A-1. The above polyols and polyisocyanates were replaced by those shown in Table 1 (in the tables, the amounts used are parts by weight), and polymerization was carried out in the same manner to obtain a polyurethane aqueous dispersion A-
2 to A-10 were obtained. Examples 1,3 to 8 and Comparative Examples 1,2,4,5 <Method for producing copolymer aqueous dispersion (1)> Polyurethane aqueous dispersion A-1 obtained by the above method
0.5 parts by weight of potassium persulfate 0.3 parts by weight, sodium hydrogen carbonate 0.25 parts by weight, sodium dodecylbenzenesulfonate 1.0 parts by weight, polyoxyethylene nonylphenyl ether (ethylene oxide addition mole number 50) 0.8 parts by weight and water 85 parts by weight. The reaction vessel was charged and the temperature was raised to 80 ° C with stirring. On the other hand, 30 parts by weight of n-butyl acrylate, 62 parts by weight of methyl methacrylate and 8 parts by weight of methacrylic acid were added to water.
30 parts by weight and sodium dodecylbenzenesulfonate 0.45
The temperature of the polymerization system was adjusted by mixing and stirring
The mixture was continuously added to the reaction vessel while maintaining the temperature at 80 ° C., and the continuous addition was completed in a total of 3 hours to obtain an aqueous dispersion having a solid content of 47.3%. This is Example 1. The above polyurethane aqueous dispersion, monomer, polymerization initiator,
Polymerization was carried out in the same manner as in Example 2 except that the buffer was changed to that shown in Table 2 (in the table, the amount used indicates parts by weight), and the obtained aqueous dispersion was used in Examples 3, 4, 5, 6 and 7,8 and Comparative Examples 1,2,4,5. Examples 2, 9 to 11 and Comparative Example 3 <Method for producing copolymer aqueous dispersion (2)> 1.3 parts by weight of the polyurethane aqueous dispersion A-2 obtained above were added to 0.7 parts by weight of benzoyl peroxide and pyrobisulfite. 0.1 parts by weight of sodium, 0.25 parts by weight of sodium hydrogen carbonate, 1.3 parts by weight of sodium dodecyl sulfate, 1.0 part by weight of polyoxyethylene nonylphenyl ether (20 moles of ethylene oxide added) and 98 parts by weight of water were charged into a reaction vessel and stirred to 80 The temperature was raised to ° C. On the other hand, a monomer mixture consisting of 40 parts by weight of 1,3-butadiene, 45 parts by weight of styrene, 5 parts by weight of acrylamide and 10 parts by weight of acrylic acid was continuously added to the reaction vessel while maintaining the temperature of the polymerization system at 65 ° C. Then, the continuous addition was completed in a total of 10 hours to obtain an aqueous dispersion having a solid content of 51.3%. This was designated as Example 2. Polymerization was carried out in the same manner as above except that the polyurethane aqueous dispersion and the monomers shown in Table 2 were used, and the obtained aqueous dispersions were designated as Examples 9, 10 and 11 and Comparative Example 3. Table 3 shows the results of measuring the physical properties of coating films obtained from the aqueous dispersions obtained by the production methods shown in Examples and Comparative Examples. The molecular weight, particle size, film elasticity, and film toughness described in the text are measured by the following methods. (1) Method for measuring molecular weight A cation exchange resin was added to the aqueous dispersion, and then tetrahydrofuran was added, and the mixture was left standing at 25 ° C for 16 hours, and then filtered, and then filtered by Waters High Performance Liquid Chromatography ALC /
To GPC, three Toyo Soda columns (GMH-3, GMH-6, G60
00H-6) was attached and the standard polystyrene having a known molecular weight was used as a standard. (2) Measuring method of particle diameter It measured using Coulter model N-4. (3) Film elasticity The film was pulled and the superiority or inferiority was judged. (4) Toughness of film The film strength was determined according to JIS K6301. [Effects of the Invention] The aqueous copolymer dispersion obtained by the method for producing an aqueous dispersion of the present invention has a high molecular weight, and the elasticity, toughness, and
It has a much higher level of abrasion resistance, and is used for fiber, paper impregnation, paint,
It can be expected to be used in a wide variety of applications such as paper coating paints, adhesives, adhesives, water-based varnishes, water-based inks, and protective coatings.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification number Office reference number FI technical display area C08F 220: 02) (56) References JP 59-138211 (JP, A) JP 56 -90817 (JP, A) JP-A-50-115288 (JP, A) JP-A-62-212455 (JP, A)

Claims (1)

(57) [Claims] A method for obtaining an aqueous dispersion by copolymerizing the following monomer mixture (B) in the presence of the following polyurethane aqueous dispersion (A), wherein the pH of the polymerization system is 7 or less, and The amount used is (A) based on 100 parts by weight of solid content (B)
A method for producing an aqueous dispersion, which comprises 0.01 to 2.5 parts by weight. Polyurethane aqueous dispersion (A): A polyurethane aqueous dispersion obtained from an aliphatic, aromatic or alicyclic polyisocyanate compound having two or more isocyanate groups, or a prepolymer having an isocyanate group at the terminal, and a polyol. Monomer mixture (B): A monomer mixture containing an α, β-unsaturated carboxylic acid, which is 0.5 to 30% by weight based on the whole monomer mixture (B). 2. The particle size of the aqueous polyurethane dispersion (A) is 0.03 to 0.
The method for producing the aqueous dispersion according to claim 1, which has a size of 4 μm.