JPH0211603B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for producing an aqueous dispersion of a polymer or copolymer, and a polymerization initiator for the polymer or copolymer. The aqueous dispersions provide coatings with particularly good water resistance, adhesion and other properties. Aqueous dispersions of various polymers in emulsion and dispersion states have been known for a long time, and these are widely used industrially as latex paints, latex adhesives, latex coating materials, etc. It has been produced and put into practical use for various purposes. Since such an aqueous dispersion uses water as a dispersion medium, it is extremely ideal since it has no problems of flammability, air pollution, or toxicity to the human body during use. On the other hand, as those used for similar purposes,
Examples include solvent-based paints, solvent-based adhesives, and solvent-based coating materials in which various polymers are dissolved in organic solvents.These solvent-based products are more flammable, air polluting, and harmful to the human body than the aforementioned aqueous dispersions. It has major problems in terms of toxicity and waste of resources. Nevertheless, the reason why such solvent-based paints, solvent-based adhesives, solvent-based coating materials, etc. are widely used is because they are far superior in properties such as water resistance and adhesiveness compared to the aqueous dispersions mentioned above. Because there is. In other words, in order to stabilize the dispersion state of an aqueous dispersion, a considerable amount of water-soluble substances such as emulsifiers, colloid stabilizers, electrolytes, etc. must be used, resulting in decreased water resistance, decreased adhesion, etc. This results in serious deficiencies. Therefore, if such deficiencies of aqueous dispersions can be eliminated, in addition to the above-mentioned advantages of aqueous dispersions, they also have the advantage of being low in viscosity and capable of high solid content concentrations; The usefulness will be significantly increased, and it will be of great value both industrially and socially. Naturally, attempts have been made to solve the problems of aqueous dispersions in the past, and one major direction is the idea of soap-free latex, that is, using no emulsifiers or colloidal stabilizers at all, or Alternatively, a method of reducing the amount of use of the emulsifier or colloid stabilizer to a polymer, or a method of chemically bonding the emulsifier or colloid stabilizer to the polymer to eliminate free emulsifier or colloid stabilizer, etc., have been considered. The former method, that is, a method that does not use an emulsifier or a colloid stabilizer, has problems in that the stability of the aqueous dispersion produced is extremely poor and the solid content concentration is low, and it is not suitable for practical use. Next, as a method for chemically bonding an emulsifier or the like into a polymer, various studies have been made to use a copolymer emulsifier. However, this method
For example, during emulsion polymerization, homopolymerization of a copolymerizable emulsifier occurs in the aqueous phase, causing problems such as a significant increase in viscosity due to the emulsifier homopolymer, and a decrease in water resistance and adhesiveness. It has not become familiar. From a completely different perspective, the present inventors made extensive efforts to obtain an aqueous dispersion with excellent water resistance, adhesive properties, etc., and as a result, the results were shown by the general formula (). (R ₁ , R ₂ , R ₃ , R ₄ , R ₅ represent a hydrogen atom, a halogen atom, or an organic group. However, R ₁ = R ₂ = R ₃ = R ₄ = R ₅ = a hydrogen atom or a halogen atom. ) and completed the present invention by discovering that an aqueous dispersion of a polymer or copolymer could be produced by using an emulsifier-type peroxide with an HLB value in the range of 2 to 100 as an initiator. I came to the conclusion. The present invention will be explained in detail below. The aqueous dispersion used in the present invention refers to an aqueous dispersion composed of polymer particles obtained by emulsion polymerization. Usually, such an aqueous dispersion is obtained by emulsion polymerization in the presence of an emulsifier, a colloid stabilizer, and a radical polymerization initiator. The aqueous dispersion limited in the present invention has the general formula () It can be obtained by using the emulsifier-type peroxide represented by as an emulsifier and a polymerization initiator. That is, the emulsifier-type peroxide represented by the general formula () is a compound that has the function of an emulsifier, that is, the emulsifying effect of the monomer and the stabilizing effect of the aqueous dispersion produced, and at the same time has the function of initiating polymerization. As the polymerization progresses, the decomposition products of this compound (2) are chemically bonded into the polymer as initiator fragments, yielding an aqueous dispersion that provides a coating film with extremely excellent water resistance and adhesive properties. The emulsifier-type peroxide referred to here is represented by the general formula () as described above, where R ₁ ,
R ₂ , R ₃ , R ₄ and R ₅ each represent a hydrogen atom, a halogen atom, or an organic group, and must be a compound having an HLB value in the range of 2 to 100. If the HLB value is less than 2 or greater than 100, the compound (2) does not have sufficient emulsifying power and smooth emulsion polymerization cannot proceed, making it impossible to obtain the desired aqueous dispersion. The HLB value here is a parameter that represents the properties of the emulsifier, and can be measured or calculated using various methods.The HLB value defined in the present invention is calculated using the following formula and Table 1. The value obtained by HLB value = Inorganic value / Organic value x 10 Here, the organic value is the value of one carbon atom 20
It is determined that Inorganic values are calculated using the values shown in Table 1.

【table】

[Table] In general, the higher the HLB value, the higher the degree of hydrophilicity, and the lower the HLB value, the higher the degree of lipophilicity. However, the emulsifier-type peroxide used in the present invention is characterized by a wide range of HLB values. Even when the HLB value is small, that is, it is close to oil-soluble, it can be used satisfactorily. In order for the compound represented by the general formula () to have an HLB value within the range defined by the present invention, the balance between inorganic groups and organic groups is important as described above. Any of the groups shown in 1 may be used, but in particular, carboxylic acid groups, carboxylic acid groups,
Preferred are a sulfate ester group, a sulfate ester base, a sulfonic acid group, a sulfonic acid group, a phosphoric acid group, a phosphate group, an amino group, an amine base, an ammonium base, an ether group, and a hydroxyl group. Of course, it may have two or more such inorganic groups. The value of the organic group can be controlled by the number of carbon atoms, but the total number of carbon atoms is preferably at least 5 or more. The compound represented by the general formula () used in the present invention can be synthesized by various methods in principle, but the compound represented by the general formula () can be synthesized by singlet oxygen oxidation. Preferred are methods of oxidizing the indicated compounds. Here, singlet oxygen is one of the active oxygen species and can be generated by various methods, such as a method by reaction of hydrogen peroxide and sodium hypochlorite,
Examples include a method in which oxygen molecules are converted to singlet oxygen by microwave discharge, and a method in which oxygen molecules are converted into singlet oxygen by irradiation with visible light in the presence of a sensitizing substance. A method using visible light irradiation, a so-called photosensitized oxidation method, is most preferred from the viewpoint of product separation.
In such photosensitized oxidation reaction systems, dye-based compounds such as rose bengal, methylene blue, and tetraphenylporphin are used as sensitizing substances,
These may be used by being dissolved in a medium together with the oxidizable material, or may be used as a so-called heterogeneous sensitizer, in which such a sensitizing substance is insolubilized on a carrier [JP-A-55-115484 Publication No. (Special Application 1987-)
21829) and Japanese Patent Application Laid-open No. 115485 (Sho 55-115485)
54-21830)] Particularly, if the latter method is used, separation of the product and the sensitizer becomes extremely easy. As the visible light source, sunlight may be used, or an artificial light source such as a halogen lamp, sodium lamp, or tungsten lamp may be used. The reaction temperature is usually around room temperature, and there is no need for special heating.If necessary, the reaction can proceed sufficiently even under cooling conditions, making it extremely useful as a means of synthesizing particularly thermally unstable peroxides. It's advantageous. The most important feature is that the peroxide produced under such reaction conditions does not undergo any secondary decomposition, which is essentially different from peroxide synthesis by other oxidation methods. , it is possible to set ideal production conditions that inevitably result in high conversion and high yield. This greatly shortens the process of separating and purifying peroxides, which poses fatal difficulties in peroxide synthesis, especially in the synthesis of peroxides with complex functional groups, and in many cases, after the reaction, It becomes possible to use it as it is as a polymerization initiator without any particular purification. Due to these advantages, the present inventors synthesized a large number of emulsifier-type peroxides and studied their properties, which led to the discovery of the aqueous dispersion of the present invention. An example of a compound represented by the general formula () is etc. When carrying out emulsion polymerization using the emulsifier-type peroxide represented by the general formula (), it can be carried out in the same manner as ordinary emulsion polymerization. That is, emulsion polymerization can be carried out by decomposition means such as thermal decomposition, redox decomposition, or photodecomposition. The monomer used in the present invention may be any monomer that can be radically polymerized or copolymerized, but examples include vinyl monomers such as vinyl chloride, vinyl acetate, vinyl carbazole, and vinyl pyrrolidone. Aromatic alkenyl monomers such as styrene, P-methylstyrene and vinylpyridine, acrylics such as acrylic acid, methyl acrylate, butyl acrylate, methacrylic acid, methyl methacrylate, acrylonitrile and methacrylamide, methacryl Examples include vinylidene monomers such as vinylidene chloride and vinylidene cyanide, olefin monomers such as ethylene and α-olefin, and diene monomers such as butadiene, isoprene, and chloroprene. When carrying out such emulsion polymerization, there is no problem in adding a conventional emulsifier or colloid stabilizer as an auxiliary to the extent that it does not affect various physical properties. As mentioned above, the use of the aqueous dispersion of the present invention exhibits excellent water resistance, adhesiveness, and other properties, making it extremely useful for paints, adhesives, coating materials, paper processing agents, fiber processing agents, and other applications. usefully used. The present invention will be explained in more detail with reference to Examples below. Reference Example 1 Dissolve 10g of each compound shown in Table 2 in 1000ml of water, add 100mg of Rose Bengal,
Using an internal irradiation type photoreaction device with a built-in 400W sodium lamp, the reaction was carried out for 6 hours under oxygen bubbling for 25 minutes.
By reacting at ℃, a reaction solution containing peroxide as the main component shown in Table 3 was obtained.

【table】

【table】

【table】

[Table] Reference Example 2 A solution in which 10 g of each of the compounds shown in Table 4 and 50 mg of tetraphenylporphin were dissolved in 50 ml of methylene chloride was added to 1000 ml of water, and the mixture was sufficiently stirred with a homomixer to emulsify. According to Reference Example 1, a reaction solution containing peroxide as a main component shown in Table 5 was obtained by photooxidation.

【table】

[Table] The peroxide reaction solution obtained in Reference Examples 1 and 2 was mixed with acetic acid.
Table 6 shows the results of determining the amount of active oxygen using the potassium iodide method. In addition, the thermal decomposition rate at 90℃ was measured, and the half-life time at that temperature is also shown in Table 6.
Shown below.

【table】

[Table] Percentage divided by the molecular weight of a substance.
Example 1 Emulsion polymerization was carried out at 25° C. for 10 hours using the following charging composition.

[Table] The latex produced had a bluish-white color and maintained an extremely stable latex state. The polymerization results at that time are shown in Table 7. Examples 2 to 8 The same procedure as in Example 1 was carried out except that peroxide No. 1 was replaced with peroxide Nos. 2 to 8, respectively. In both cases, extremely stable latexes were obtained.
The polymerization results at that time are shown in Table 7.

【table】 Example 9 Emulsify at 70℃ for 30 hours with the following preparation composition.

[Table] When polymerization was carried out, an extremely stable latex with a polymerization rate of 99% was obtained. Example 10 Emulsification at 40℃ for 48 hours with the following preparation composition

[Table] When polymerization was carried out, an extremely stable latex was obtained with a polymerization rate of 95%. Example 11 Emulsification at 30℃ for 10 hours with the following preparation composition

[Table] When polymerization was carried out, an extremely stable latex was obtained with a polymerization rate of 99%. Example 12 Emulsion polymerization was carried out at 25°C for 12 hours using the following charge composition, resulting in a stable white product with a polymerization rate of 98%.

[Table] Colored latex was obtained. The precipitated solid content was 15%. Example 13 Emulsion polymerization was carried out in exactly the same manner as in Example 12 except that peroxide No. 12 was used instead of peroxide No. 11. The polymerization rate was 95% and the precipitated solid content was 1.8.
% white latex was obtained. Comparative Example 1 Emulsion polymerization was attempted using exactly the same procedure as in Example 12 except that peroxide No. 13 was used instead of peroxide No. 11, but no polymerization occurred even after 72 hours had passed. . Example 14 The latex obtained in Example 11 was dissolved in tetrahydrofuran, and this solution was dropped into a large amount of water to obtain a polymer suspension. This suspension was separated to yield a white polymer and a clear liquid. After distilling off tetrahydrofuran from this liquid under reduced pressure, the anionic surfactant contained in the resulting aqueous solution was analyzed by titration with octadecyldimethylbenzyl ammonium chloride using an alkaline phase separation method to determine the soap-free rate. The results are shown in Table 8. However, the soap-free rate was calculated using the following formula. Soap-free rate (%) = A-B/A x 100 where A is the amount of emulsifier-type peroxide charged (g),
B is the amount (g) of free emulsifier in the latex determined by surfactant analysis. Next, the white polymer obtained by the above operation was dried under vacuum, and then the number average molecular weight was determined by gel permeation chromatography. Furthermore, the carboxylic acid base in the polymer chain was quantified using its characteristic absorption at 1720 cm ^-1 by analyzing the infrared absorption spectrum. The above results are summarized in Table 8, and it can be seen that most of the emulsifier-type initiator used was introduced into the styrene polymer chains as decomposition product fragments.

[Table] The analytical instruments used were a Waters liquid chromatograph (column: shodex 80M) and a Hitachi infrared spectrophotometer model 295. Example 15 The soap-free rate of the latex obtained in Example 1 was determined by the same procedure as in Example 14. Next, the latex was cast on a thoroughly cleaned 100 mm x 100 mm glass plate so that the dry coating thickness was 30 μm, and heated at 80°C for 3 hours to obtain a continuous transparent latex coating. . The water resistance and adhesion to glass of the obtained latex film were measured. The results are shown in Table-9. However, the water resistance is determined by applying the latex coating to the glass plate.
It was immersed in water at 30°C and judged based on its appearance 12 hours later. The adhesive strength was measured by cutting the film into a 25 mm width and measuring the adhesive strength at 180 degrees peeling at 23°C using a tensile tester. Example 16 The soap-free rate, water resistance, and adhesive strength to glass of the latex obtained in Example 2 were measured according to Example 15. The results are shown in Table-9.
However, when measuring the soap-free rate, an aqueous solution of caustic soda was added to the latex, and the pH was set to 10. Example 17 The soap-free rate, water resistance, and adhesive strength to glass of the latex obtained in Example 4 were measured according to Example 15. The results are shown in Table-9. However, the amount of free emulsifier was measured using the Epton method as a surfactant analysis method when measuring the soap-free rate. Example 18 The soap-free rate, water resistance, and adhesive strength of the latex obtained in Example 3 were measured according to Example 17, and the results are shown in Table 9. However, when measuring the soap-free rate, an aqueous solution of caustic soda was added to the latex to adjust the pH to 7 before analysis. Example 19 The soap-free rate, water resistance and adhesive strength of the latex obtained in Example 5 were measured in exactly the same manner as in Example 17. The results are shown in Table-9. Example 20 The soap-free rate, water resistance, and adhesive strength of the latex obtained in Example 6 were measured according to Example 18. The results are shown in Table-9. Example 21 The soap-free rate, water resistance and adhesive strength of the latex obtained in Example 7 were measured according to Example 17. The results are shown in Table-9. Example 22 The water resistance and adhesive strength of the latex obtained in Example 8 were measured according to Example 15. Furthermore, when measuring the soap-free rate, an excess amount of sodium lauryl sulfate aqueous solution was added to the aqueous solution from which the polymer had been separated, and the excess sodium lauryl sulfate was analyzed by the Epton method. The above results are shown in Table-9. Comparative Example 2 Emulsion polymerization was carried out at 25°C for 10 hours using the following charging composition, resulting in a bluish-white color with a polymerization rate of 98%.

[Table] Latex was obtained. The soap-free rate, water resistance, and adhesive strength to glass of this latex were measured according to Example 17. Display the results.
9.

[Table] Comparative Example 3 When emulsion polymerization was attempted using exactly the same procedure as in Example 9 except that peroxide No. 13 was used instead of peroxide No. 9, most of the polymer precipitated and the latex was It didn't generate at all. Comparative Example 4 Exactly the same procedure as in Example 10 was performed except that sodium propanesulfonate hydroperoxide [HOO C(CH ₃ ) ₂ SO ₃ Na; HLB value 141] was used instead of peroxide No. 10. When emulsion polymerization was attempted, the polymerization rate was 35% and the precipitated solids were 20%, and a stable and homogeneous latex could not be obtained.

Claims (1)

[Claims] 1 Represented by the general formula () (R ₁ , R ₂ , R ₃ , R ₄ , R ₅ represent a hydrogen atom, a halogen atom, or an organic group. However, R ₁ = R ₂ = R ₃ = R ₄ = R ₅ = a hydrogen atom or a halogen atom. 1. A method for producing an aqueous dispersion of a polymer or copolymer, characterized in that an emulsifier-type peroxide having an HLB value in the range of 2 to 100 is used as an initiator. 2 Emulsifier type peroxide is R ₁ , R ₂ , R ₃ , R ₄ , R ₅
Carboxylic acid group, carboxylic acid base, sulfuric ester group, sulfuric ester base, sulfonic acid group, sulfonic acid group, phosphoric acid group, phosphoric acid group, amino group, amine base, ammonium base,
The method for producing an aqueous dispersion according to claim 1, which has at least one or two or more hydrophilic groups selected from the group of ether groups and hydroxyl groups.