JPS6239163B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for producing an aqueous polymer dispersion having excellent dispersion stability, in which a block copolymer is uniformly dispersed in water or a solution of water and a water-soluble organic solvent. Aqueous polymer dispersions are used in a wide range of applications, including paints, printing inks, textile processing, paper processing, leather processing, adhesives, and pressure-sensitive adhesives. In particular, water-based paints that use water as a solvent are safe and hygienic from the standpoint of pollution-free and resource-saving, and there is no risk of depletion of the raw material.Water-based paints will have great significance as future paints. be. Conventionally, one method for producing such an aqueous polymer dispersion is to use a dispersion stabilizer soluble in water or a solution of water and a water-soluble organic solvent to form a polymer insoluble in the liquid. There is a method of manufacturing by graft polymerizing type monomers. For example, as dispersion stabilizers, maleated polybutadiene (Japanese Patent Publication No. 49-43381), water-soluble unsaturated polyester (Japanese Patent Publication No. 53-9795), water-soluble polymers with polymerizable vinyl groups introduced into the molecule (Japanese Patent Publication No. 53-9795), Grafting of a vinyl monomer that becomes a polymer insoluble in water or a solution of water and a water-soluble organic solvent in the presence of these dispersion stabilizers using methods such as JP-A No. 53-17680). It has been proposed to carry out polymerization. However, these methods not only have complicated steps, but also have low polymerization yields in the grafting process, resulting in long reaction times and low productivity.Also, low grafting efficiency results in poor mechanical stability and poor productivity of the resulting dispersion. The drawback was poor storage stability. Furthermore, when maleated polybutadiene or unsaturated polyester is used as a dispersion stabilizer, it has poor compatibility with acrylic copolymers, making it difficult to obtain uniformity on the coating surface in paint applications, for example, and making it resistant to weathering. It had the disadvantage of being inferior in quality. As described above, conventional methods for producing aqueous polymer dispersions have various drawbacks, and satisfactory results have not yet been obtained. An object of the present invention is to provide a new method for industrially producing aqueous polymer dispersions, which eliminates the drawbacks of the conventional methods as described above. That is, the outline of the manufacturing method of the present invention is as follows. First, the main raw material compounds used in the present invention include polymeric peroxide, two types of vinyl monomers shown in (a) and (b) below, and a solution of water and a water-soluble organic solvent. Therefore, it will be explained below. The polymer peroxide used in the present invention has the general formula () [In the formula, R ₁ represents an alkylene group or substituted alkylene group having 1 to 18 carbon atoms, a cycloalkylene group or substituted cycloalkylene group having 3 to 15 carbon atoms, or a phenylene group or a substituted phenylene group,
R ₂ is an alkylene group or substituted alkylene group having 2 to 10 carbon atoms,

[Formula] (In the formula, R ₃ is a hydrogen atom or a methyl group, and R ₄ is an alkylene group or substituted alkylene group having 2 to 10 carbon atoms. Also, m = 1 to 13.)

[expression] or

Represents [formula]. and a polymeric peroxide represented by the general formula () [In the formula, R ₁ and n are the same as in the above general formula (). ] One or more polymeric peroxides selected from the group consisting of polymeric peroxides shown in the following. Other raw material compounds include one or more vinyl monomers to be copolymerized with the polymeric peroxide in (a), and the polymer is soluble in water or a solution of water and a water-soluble organic solvent. (b) One or more other vinyl monomers different from the vinyl monomer shown in (a), the polymer of which has water or a water-soluble organic A vinyl monomer that does not dissolve in a solution with a solvent; (c) A polymer of vinyl monomers that is a constituent component of the peroxy bond-containing copolymer is dissolved in a solution of water and a water-soluble organic solvent. However, there is a solution that does not dissolve a polymer of other vinyl monomers to be block copolymerized with the peroxy bond-containing copolymer. The production method of the first invention involves copolymerizing a polymeric peroxide and the vinyl monomer shown in (a) to produce a peroxy bond-containing copolymer, and then copolymerizing the peroxy bond-containing copolymer with (a). A method of producing an aqueous polymer dispersion by block copolymerizing the vinyl type monomer shown in (c) in a water-soluble organic solvent and then adding water or a solution of water and a water-soluble organic solvent shown in (c). be. The second invention is the same as the first invention in the first step, and the second invention uses a peroxy bond-containing copolymer and the vinyl monomer shown in (b) instead of the second method of the first invention. A method is used in which block copolymerization is performed in a water-soluble organic solvent, the water-soluble organic solvent is removed, and water is subsequently added. Specifically, the polymeric peroxide represented by the above general formula () is, for example, etc. can be given. Specifically, the polymeric peroxide represented by the above general formula () is, for example, etc. can be given. The copolymerization mechanism of these polymeric peroxides and vinyl monomers and the block copolymerization mechanism of the resulting peroxy bond-containing copolymer and other vinyl monomers can be explained as follows. can. First, by polymerizing the vinyl type monomer shown in (a) using polymeric peroxide, a copolymer in which peroxy bonds are introduced into the chain is obtained. When the vinyl type monomer shown in (b) is added to this in a water-soluble organic solvent and polymerized, the peroxy bond-containing copolymer is cleaved at the peroxy bond, and a block copolymer can be efficiently obtained. This block copolymer consists of a polymer part that is soluble in water or a solution of water and a water-soluble organic solvent, and a polymer part that is insoluble in water or a solution of water and a water-soluble organic solvent. By adding water or a solution of water and a water-soluble organic solvent to
The insoluble polymer portion aggregates into particles, and the soluble polymer portion extends into the liquid, resulting in an overall state in which particles are dispersed. Examples of the water-soluble organic solvent used in the present invention include methyl alcohol, ethyl alcohol, n-
Propyl alcohol, iso-propyl alcohol, tert-butyl alcohol, methyl cellosolve, ethyl cellosolve, butyl cellosolve, methoxybutyl alcohol, methyl carbitol, ethyl carbitol, acetone, dioxane, methyl cellosolve acetate, carbitol acetate, diacetone alcohol, etc. Those that dissolve in any proportion with water at room temperature, such as n-butyl alcohol, iso-butyl alcohol, sec-butyl alcohol, methyl ethyl ketone, methyl acetate,
Some substances, such as ethyl acetate and cellosolve acetate, have a solubility in water of 7 to 25% at room temperature. When using these, they must be selected appropriately depending on the solubility of the soluble polymer portion and the insoluble polymer portion of the block copolymer of the present invention. The vinyl monomer defined in (a) to be copolymerized with the polymeric peroxide in the present invention means, for example, hydroxyethyl (meth)acrylate, hydroxyethyl (acrylate), and hydroxyethyl methacrylate. Same.),
2-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, diethylene glycol mono(meth)acrylate, triethylene glycol mono(meth)acrylate, triethylene glycol mono(meth)acrylate esters, mono(meth)acrylic acid polyethylene glycol esters, such as mono(meth)acrylic acid pentaethylene glycol ester, mono(meth)acrylic acid dipropylene glycol ester, mono(meth)acrylic acid tripropylene glycol ester, Mono(meth)acrylic acid polypropylene glycol esters such as mono(meth)acrylic acid pentapropylene glycol ester, (meth)acrylamide such as (meth)acrylamide, N-methylol(meth)acrylic acid amide, diacetone acrylamide, etc. There are derivatives, vinyl acetate, etc., and one or more of these vinyl type monomers are used. In this case, vinyl as defined in (b) above can be dissolved in water or a solution of water and a water-soluble organic solvent to the extent that the vinyl-type monomer-based polymer portion of the desired peroxy bond-containing copolymer can be dissolved in water or a solution of water and a water-soluble organic solvent. Type monomers can be added. The mixing ratio in a mixture of the vinyl monomer defined in (a) and the vinyl monomer defined in (b) will depend on the combination of both vinyl monomers. Although it is different and cannot be uniformly identified, (b)
The content of the vinyl monomer defined in the mixture is usually in the range of 1 to 50% by weight. In addition, other vinyl monomers defined in (b) to be block copolymerized with the peroxy bond-containing copolymer in the present invention include, for example, butadiene, styrene, vinyl propionate, vinyl chloride, vinylidene chloride. , (meth)acrylonitrile, methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, isopropyl (meth)acrylate, butyl (meth)acrylate, isobutyl (meth)acrylate, tert-butyl (meth)acrylate, n-hexyl (meth)acrylate, cyclohexyl (meth)acrylate, octyl (meth)acrylate, benzyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, ) lauryl acrylate, (meth)
Examples include stearyl acrylate, (meth)acrylic acid glycidyl ester, (meth)acrylic acid methyl glycidyl ester, (meth)allyl glycidyl ether, vinyltoluene, vinylpyrrolidone, dibutyl fumarate, and one or more of these. vinyl type monomers are used. In this case, (a) within the range in which the vinyl monomer-based block polymer portion of the target block copolymer does not dissolve in water or a solution of water and a water-soluble organic solvent.
The vinyl type monomer defined in (b) can be added to the vinyl type monomer defined in (b). The mixing ratio in a mixture of the vinyl monomer defined in (b) and the vinyl monomer defined in (a) will depend on the combination of both vinyl monomers. Although they vary and cannot be uniformly identified,
The content of the vinyl monomer defined in (a) in the mixture is usually within the range of 0.1 to 50% by weight. The peroxy bond-containing copolymer used in the present invention is prepared by combining one or more polymeric peroxides selected from the group consisting of polymeric peroxides represented by general formula () and general formula () in a water-soluble organic solvent. It can be easily obtained by copolymerizing one or more vinyl monomonomers. In this case, the amount of polymer peroxide used is 0.5 to 20 parts by weight per 100 parts by weight of the vinyl monomer, the polymerization temperature is 60 to 130°C, and the polymerization time is 2 to 5 parts by weight.
Each time is within a suitable range. Here, the polymerization temperature of the block copolymerization reaction is 60~
A temperature of 140°C and a polymerization time of 3 to 6 hours are suitable. At this time, the ratio of the vinyl type monomer and water-soluble organic solvent used in the block copolymerization reaction is not particularly limited. In addition, the mixing ratio of water and water-soluble organic solvent in the aqueous polymer dispersion in the present invention is such that the water-soluble organic solvent is
80% or less is preferable. The amount of water or water and water-soluble organic solvent to be used is within a range such that the solid content concentration in the aqueous polymer dispersion to be produced is 30 to 70%, that is, the content of the water-soluble organic solvent in the aqueous polymer dispersion. A ratio of 70 to 30% is preferred. Further, the ratio of the soluble polymer portion to the insoluble polymer portion in the block copolymer is not particularly limited, but from the viewpoint of stability of the dispersion of the present invention, the amount of the soluble polymer portion is smaller than the insoluble polymer portion. 5 to 70% by weight, based on the total amount of soluble polymer portion and soluble polymer portion, is suitable. The aqueous polymer dispersion of the present invention is useful as a coating composition, and other resins, pigments, fillers, and various additives can be added as necessary.
Typical examples of resins that can be added include melamine resin, epoxy resin, and vinyl resin. As described above, the method for producing an aqueous polymer dispersion of the present invention has the following advantages over conventional methods, and its industrial value is extremely high. (1) Conventional methods involve a three-step process in which a soluble polymer is synthesized, a functional group such as a vinyl group is introduced into the polymer molecule, and an insoluble polymer portion is generated by grafting or block copolymerization. In contrast to conventional manufacturing processes, according to the present invention, a peroxy bond-containing copolymer is synthesized by copolymerizing a polymeric peroxide and a vinyl monomer, and the peroxy bond in the polymer molecule is directly cleaved. Because of the two-step production process in which the insoluble polymer portion is produced by block copolymerization, the production process is simple and industrially advantageous. (2) Most of the produced polymers are block copolymers consisting of a polymer part that is soluble in water or a solution of water and a water-soluble organic solvent, and a polymer part that is insoluble, so the solid content is high. Furthermore, an aqueous polymer dispersion with low viscosity and extremely excellent dispersion stability can be obtained. (3) The coating composition prepared using the aqueous polymer dispersion of the present invention has a cured film with excellent smoothness and can form a continuous coating layer with high gloss. Next, the effectiveness of the present invention will be described in more detail with reference to Examples, but the present invention is not limited to these Examples. In addition, all "parts" in the examples represent parts by weight. Example 1 (A) Production of peroxy bond-containing copolymer 20 parts of ethyl cellosolve was charged into a reactor equipped with a thermometer, a stirrer, and a reflux condenser, and heated to 75°C while blowing nitrogen gas. A mixed solution () having the composition shown below was gradually added over a period of 1 hour.

[Table] After the completion of the preparation, the polymerization reaction was continued for 1.5 hours. The product is a peroxy bond-containing copolymer.
It was a clear solution containing 37.4% by weight and a viscosity of 0.4 poise at 25°C. (B) Production of aqueous polymer dispersion 20 parts of ethyl cellosolve was charged into a reactor equipped with a thermometer, a stirrer, and a reflux condenser, heated to 80°C while blowing nitrogen gas, and the mixture shown in Table 2 was added. The mixture () was added dropwise over 2 hours. Table 2 Composition of mixture () Peroxy bond-containing copolymer solution obtained from (A)
60 parts Methyl methacrylate 20 parts Butyl acrylate 20 parts Styrene 20 parts A block copolymer dispersion can be obtained by keeping the reactant at 80°C for 3 hours. By adding 120 parts of water to the resulting solution, An aqueous polymer dispersion containing 31.5% by weight of a block copolymer, having a viscosity of 0.3 poise at 25°C, and a milky white color was obtained using water and ethyl cellosolve as dispersion media. This dispersion remained stable even after being left at 25°C for 6 months, with no particle sedimentation, phase separation, or viscosity change observed. When this dispersion was applied to a steel plate to a dry film thickness of 30 to 40 μm and force-dried at 140°C for 30 minutes, the film was smooth and glossy, and no foaming or sagging was observed. Nakatsuta. Example 2 (A) Production of peroxy bond-containing copolymer A peroxy bond-containing copolymer was produced in the same manner as in Example 1 (A). However, in Example 1
In (A), 20 parts of isopropyl alcohol was used instead of the 20 parts of ethyl cellosolve initially charged in the reactor, and the mixture () shown in Table 3 was used instead of the mixture (), and the polymerization temperature of the copolymerization reaction was adjusted. 90
℃.

【table】

[Table] The product also contains 36.7% by weight of a peroxy bond-containing copolymer and has a viscosity of 1.9 at 25°C.
It was a clear solution of poise. (B) Production of aqueous polymer dispersion An aqueous polymer dispersion was produced in the same manner as in Example 1 (B). However, the ethyl cellosolve initially charged in the reactor in (B) of Example 1
Using 10 parts of ethyl cellosolve instead of 20 parts, using the mixture () shown in Table 4 instead of the mixture () of (B) in Example 1, and setting the polymerization temperature of the block copolymerization reaction to 95°C. A block copolymer dispersion was obtained. Table 4 Composition of mixed solution () Peroxy bond-containing copolymer solution 60 parts Methyl methacrylate 60 parts Butyl methacrylate 40 parts Styrene 30 parts The obtained block copolymer dispersion was dissolved in 1700 parts of n-hexane. was added to the solution while stirring at room temperature and left to stand to obtain a white precipitate. This precipitate was over-separated, dried under reduced pressure at room temperature, pulverized, and then 100 parts of water was added to obtain water containing 55.0% by weight of the block copolymer and having a viscosity of 7.5 poise at 25°C and a milky white color. An aqueous polymer dispersion liquid using only this as a dispersion medium was obtained. This dispersion remained stable even after being left at 25°C for 6 months, with no particle sedimentation, phase separation, or viscosity change observed. When this dispersion was subjected to a coating test in the same manner as in Example 1, the coating film was smooth and glossy, with no phenomena of foaming or sagging observed. Example 3 (A) Peroxy bond-containing copolymer The peroxy bond-containing copolymer solution obtained in Example 2 (A) was used. (B) Production of aqueous polymer dispersion An aqueous polymer dispersion was produced in the same manner as in Example 2 (B). However, instead of the mixture () used in Example 2 (B), the mixture () shown in Table 5 was used to obtain a block copolymer dispersion. Table 5 Composition of mixed solution () Peroxy bond-containing copolymer solution 60 parts Methyl methacrylate 30 parts Butyl methacrylate 30 parts Styrene 30 parts Hydroxyethyl methacrylate 10 parts The obtained block copolymer dispersion Using the same method as in Example 2 (B), an aqueous polymer dispersion was obtained. This aqueous polymer dispersion contains 54.4% by weight of block copolymer, has a viscosity of 6.1 poise at 25°C, is milky white in color, and is an aqueous polymer dispersion containing only water as a dispersion medium. . This aqueous polymer dispersion remained stable even after being left at 25° C. for 6 months, with no particle sedimentation, phase separation, or viscosity change observed. When this aqueous polymer dispersion was subjected to a coating test in the same manner as in Example 1, the coating film was smooth and glossy, and no foaming or sagging phenomena were observed. Example 4 (A) Peroxy bond-containing copolymer The peroxy bond-containing copolymer solution obtained in Example 1 (A) was used. (B) Production of aqueous polymer dispersion A dispersion was produced in the same manner as in Example 1 (B). However, instead of the mixed solution (B) of Example 1,
A block copolymer dispersion was obtained using a mixed solution () having the composition shown in the table. Table 6 Composition of mixed solution () Peroxy bond-containing copolymer solution 60 parts Methyl methacrylate 25 parts Ethyl methacrylate 25 parts Hydroxyethyl methacrylate 9 parts Acrylic acid 1 part Obtained block copolymer dispersion An aqueous polymer dispersion was obtained by adding 120 parts of water to the solution. The resulting aqueous polymer dispersion contained 31.5% by weight of the block copolymer and had a viscosity of 0.3 at 25°C.
It was poise and had a milky white color. This aqueous polymer dispersion remained stable even after being left at 25°C for 6 months, with no particle sedimentation, phase separation, or viscosity change observed. Further, when this aqueous polymer dispersion was subjected to a coating test in the same manner as in Example 1, the coating film was smooth and glossy, and no phenomena of foaming or sagging were observed. Examples 5 to 9 (A) Production of peroxy bond-containing copolymers Production was carried out in the same manner as in Example 1 (A).
However, instead of 20 parts of ethyl cellosolve in Example 1, the solvent shown in Table 7 was used, and in place of the mixed solution () of Example 1, the mixed solution shown in Table 7 was used,
Further, the polymerization temperature of the copolymerization reaction was 90°C in Example 5 and 100°C in Example 7.
Further, the content (wt%) of the peroxy bond-containing copolymer in the product and the viscosity of the peroxy bond-containing copolymer solution at 25°C are as shown in Table 7.

【table】

[Table] (B) Production of aqueous polymer dispersion A mixture having the composition shown in Table 8 was used in place of the mixture () in (B) of Example 1, and the polymerization temperature of the block copolymerization reaction was carried out. Each block copolymer dispersion was obtained according to the method (B) of Example 1 except that the temperature was 95°C in Example 5 and 105°C in Example 7. was treated as follows to produce each desired aqueous polymer dispersion. In Examples 5, 8 and 9, the amounts of water shown in Table 8 were added to the resulting block copolymer dispersions. In Example 6, the amounts of water and water-soluble organic solvent shown in Table 8 were added to the obtained block copolymer dispersion. In Example 7, the obtained block copolymer dispersion was added to n-hexane in an amount 10 times the amount of the solution at room temperature with stirring and allowed to stand to obtain a white precipitate. Next, after removing the supernatant liquid, the mixture was dried at room temperature under reduced pressure, crushed, and the amount of water shown in Table 8 was added and mixed with stirring to obtain an aqueous polymer dispersion. Further, the content of the block copolymer in the obtained aqueous polymer dispersion and the viscosity of the aqueous polymer dispersion at 25°C are as shown in Table 8.

【table】

[Table] The aqueous polymer dispersions obtained in Examples 5 to 9 were all stable even after being left at 25°C for 6 months, with no particle sedimentation, phase separation, or viscosity change observed. Furthermore, as a result of conducting a coating test in the same manner as in Example 1, all coatings were smooth and glossy.
No phenomena of foaming or sagging were observed.

Claims (1)

[Claims] 1 General formula () [In the formula, R ₁ represents an alkylene group or substituted alkylene group having 1 to 18 carbon atoms, a cycloalkylene group or substituted cycloalkylene group having 3 to 15 carbon atoms, or a phenylene group or a substituted phenylene group,
R ₂ is an alkylene group or substituted alkylene group having 2 _{to 10} carbon atoms; . Also, m = 1 to 13),
Represents [formula] or [formula]. Further, n=2 to 20. ] and the general formula () One or more polymeric peroxides selected from the group consisting of polymeric peroxides represented by the formula (wherein R ₁ and n are the same as in the general formula ()) and the following (a): A peroxy bond-containing copolymer obtained by copolymerizing one or more vinyl monomers as defined,
Block copolymerization is performed with one or more vinyl type monomers defined in (b) below in a water-soluble organic solvent to form a block copolymer, and then this block copolymer is mixed with water or the following ( A method for producing an aqueous polymer dispersion in which a block copolymer is dispersed in water or a solution of water and a water-soluble organic solvent by adding a solution of water and a water-soluble organic solvent defined in c). . (b) The one or more vinyl monomers to be copolymerized with the polymeric peroxide mentioned above are those whose polymer is soluble in water or a solution of water and a water-soluble organic solvent. . (b) One or more other vinyl monomers different from the above vinyl monomers are those whose polymers do not dissolve in water or in a solution of water and a water-soluble organic solvent. . (c) The solution of water and a water-soluble organic solvent is a solution that dissolves a polymer of vinyl monomers that is a constituent component of the peroxy bond-containing copolymer, and It is a liquid that does not dissolve the polymer of the other vinyl monomers to be block copolymerized. 2 General formula () [In the formula, R ₁ represents an alkylene group or substituted alkylene group having 1 to 18 carbon atoms, a cycloalkylene group or substituted cycloalkylene group having 3 to 15 carbon atoms, or a phenylene group or a substituted phenylene group,
R ₂ is an alkylene group or substituted alkylene group having 2 _{to 10} carbon atoms; .Also, m=1 to 13).
Represents [formula] or [formula]. Moreover, n=2-20. ] and the general formula () One or more polymeric peroxides selected from the group consisting of polymeric peroxides represented by the formula (wherein R ₁ and n are the same as in the general formula ()) and the following (a) A peroxy bond-containing copolymer obtained by copolymerizing one or more vinyl monomers defined in (b) below with one or more vinyl monomers defined in (b) below. The block copolymer is block copolymerized with a block copolymer in a water-soluble organic solvent, and then the water-soluble organic solvent is removed from the mixture of the produced block copolymer and the water-soluble organic solvent, and then water is added. A method for producing an aqueous polymer dispersion in which a polymer is dispersed in water. (b) The one or more vinyl monomers to be copolymerized with the polymeric peroxide mentioned above are those whose polymer is soluble in water or a solution of water and a water-soluble organic solvent. . (b) One or more other vinyl monomers different from the above vinyl monomers are those whose polymers do not dissolve in water or in a solution of water and a water-soluble organic solvent. . (c) The solution of water and a water-soluble organic solvent is a solution that dissolves a polymer of vinyl monomers that is a constituent component of the peroxy bond-containing copolymer, and It is a liquid that does not dissolve the polymer of the other vinyl monomers to be block copolymerized.