JP2554430B2 - Method for producing aqueous resin dispersion - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing an aqueous resin dispersion, and more particularly to a method for producing a resin dispersion having an extremely fine dispersed resin particle diameter and excellent water resistance.

[0002]

2. Description of the Related Art In recent years, from the viewpoints of air pollution, improvement of working environment on site, effective use of resources, etc., and safety against fire, organic solvent-based paints are being replaced by water-based paints, especially water-based emulsion paints. . However, ordinary water-based emulsion type paints are not as dense as organic solvent type paints because emulsion-polymerized resins dispersed in water are fused and form a film when dried, and are required for paints. It had a drawback that the water resistance of the coating was particularly poor.

In order to improve this drawback, there is known a method for producing an aqueous emulsion in which an emulsifier is not used at all or an extremely small amount is used. However, in this method, the stability in producing a resin is poor and during the reaction. The resin may agglomerate and the reaction kettle may be significantly soiled. Further, even if it is manufactured stably, it has a drawback in that when it is made into a paint, the stability of mixing with a pigment or the like is poor and the paint cannot be made.

A means for reducing the particle size is known as a method for improving the denseness of a film. However, various new problems arise due to the method for reducing the particle size.
For example, when a large amount of an emulsifier is used for the production, there is a drawback that the performance is deteriorated by the emulsifier, and particularly the water resistance of the coating film is significantly deteriorated. Further, after neutralizing an aqueous resin dispersion obtained by copolymerizing an unsaturated carboxylic acid such as acrylic acid or methacrylic acid or swelling the particle size by adding an organic solvent, a mechanical shear is applied to subdivide the particles. There is known a method for obtaining a fine particle-type aqueous dispersion resin, but the particles are not uniformly refined and coarse particles are present, so that good film coating and water resistance cannot always be obtained.

It is known that a fine particle type aqueous resin dispersion can be obtained by using a reactive emulsifier in combination with an inorganic redox catalyst (Japanese Patent Laid-Open No. 62-2831).
No. 66). However, this method also has a drawback that the emulsion stability during the production of the aqueous resin is not improved and therefore the solid content of the aqueous resin dispersion is limited to about 30% by weight at most.

[0006]

As a result of various investigations, the present inventors have found that an aqueous resin having emulsion stability during the production of an aqueous resin dispersion, the resulting resin particle size being extremely small, and excellent film water resistance. A method for producing a dispersion is provided.

[0007]

According to the present invention, 100 parts by weight of a radically polymerizable ethylenic monomer is added to a reactive emulsifier 2
In a method for producing an aqueous resin dispersion which is emulsion polymerized in the presence of -10 parts by weight, a reaction in which water, an amount of 0-70% by weight of the monomer and 10-80% by weight of the reactive emulsifier are added. A water-based resin characterized by dropping a mixture containing 30 to 100% by weight of the above monomer, 20 to 90% by weight of the above reactive emulsifier and water into a kettle and radically polymerizing with an organic polymerization initiator. The present invention relates to a method for manufacturing a dispersion.

Examples of the radically polymerizable ethylenic monomer used in the present invention include acrylic acid esters such as methyl acrylate, ethyl acrylate, butyl acrylate and 2-ethylhexyl acrylate, methyl methacrylate and methacrylic acid. Ethyl acid, butyl methacrylate, 2-ethylhexyl methacrylate, octyl methacrylate, stearyl methacrylate, (meth) acrylic acid alkyl esters such as methacrylic acid esters, styrene, α
-Styrene-based monomers such as methylstyrene and vinyltoluene, vinyl acetate, carboxylic acid vinyl esters such as vinyl propionate and vinyl versatate, acrylonitrile, methacrylonitrile and the like can be used.

Further, acrylic acid, methacrylic acid, maleic acid, fumaric acid, itaconic acid, paravinyl benzoic acid,
Carboxylic acid-based monomers such as paravinylbenzene sulfonic acid are preferably used in combination because they improve the stability during production or during storage of the aqueous resin dispersion. For this purpose, the carboxylic acid-based monomer is 0.05 to
5% by weight can be used.

Further, acrylamide, methacrylamide, N-methylol acrylamide, hydroxyethyl acrylate, hydroxypropyl acrylate, hydroxyethyl methacrylate, hydroxypropyl methacrylate, etc., for the purpose of adjusting the fluidity and drying properties of the coating material,
For the purpose of imparting a crosslinked structure, ethylene glycol dimethacrylate, divinylbenzene or the like can be used.

The reactive emulsifier of the present invention has at least one radical-polymerizable unsaturated group in the molecule, and is, for example, a sulphosuccinate-based ester represented by the following general formulas (1) and (2) ( Examples of commercially available products include Ramtel S-120, S-180PS-180A manufactured by Kao Corporation,
Sanyo Kasei Co., Ltd. Eleminol JS-2, etc., an alkylphenol ether type represented by the general formula (3) (commercially available as Aqualon HS- manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd.).
10, RN-20, etc.).

General formula (1)

Embedded image R ₁ : an alkyl group having 12 to 30 carbon atoms M ₁ : Na, NH ₄ , K general formula (2)

Embedded image General formula (3)

Embedded image R _2: an alkyl group having 8 to 12 carbon atoms X: H or _{SO 3 M 2 M 2: Na} , NH 4, K n: 50~120

In emulsion polymerization, one or two of these may be used.
A mixture of two or more species may be used, and if necessary, an emulsifier having no reactivity may be used in combination.

These emulsifiers are used in an amount of 2 to 10 parts by weight based on 100 parts by weight of the ethylenic monomer. When the amount is 2 parts by weight or less, the particle size of the resin dispersion is large, and when the amount is 10 parts by weight or more, the particle size is small.

According to the present invention, 10 to 80% by weight, preferably 20 to 70% by weight, of the reactive emulsifier is used in the dropwise polymerization.
One of the features is to charge the reaction vessel at the start of polymerization. That is, a predetermined amount of water and a part of the reactive emulsifying agent are put in a reaction vessel in advance, and the monomer is dropwise polymerized. Here, up to 70% by weight of the monomers can be added together. If the amount of the reactive emulsifier previously put in the reaction kettle is less than the above numerical value, the resin particle size becomes large, which is not preferable. The stability of the polymerization system deteriorates.

Another feature of the present invention is that an organic initiator is used as a radical polymerization initiator. The use of an inorganic peroxide such as ammonium peroxide or sodium peroxide instead of the organic peroxide is not preferable because the particle size becomes large during the polymerization process. As the organic initiator, organic peroxides such as tert-butyl perbenzoate, dilauryl peroxide, benzoyl peroxide and tert-butyl hydroperoxide are preferable.
These organic peroxides can be used alone,
It may be used in a redox form in combination with a reducing agent such as sodium ersorbate.

The organic polymerization initiator is used in an amount of 0.5 to 10 parts by weight based on 100 parts by weight of the monomer. Of these, 10 to 50% by weight of the organic polymerization initiator is added to the reaction vessel in advance, and the rest is added to the monomer and the reactive emulsifier and added dropwise.

In the present invention, the ethylene monomer to be dripped is 50 to 200 with respect to 100 parts by weight of the ethylene monomer.
It is preferable to add parts by weight of water together with the remaining amount of the reactive emulsifier as a pre-emulsion. Reaction time is 1-5
It is time, and during this period, the monomer can be continuously added dropwise or intermittently. The reaction temperature is 50 to 90 ° C.

Further, in the present invention, copper ions such as cupric sulfate and cupric chloride and transition metal ions such as ferric sulfate and ferric chloride are added to the water system of the reaction vessel at 10 ^-7 to 10 ^-5. It can be added in the range of mol / liter.

In the emulsion polymerization of the present invention, sodium acetate, sodium citrates, sodium bicarbonate, etc. are used as buffering agents, polyvinyl alcohol as a protective colloid, and water-soluble cellulose derivatives are stearyl as chain transfer agents. Mercaptan such as mercaptan and t-dodecyl mercaptan can be used.

The aqueous resin dispersion of the present invention has an average particle size of 25.
It is obtained as a dispersion of a resin of -100 nm, preferably 35-80 nm. A solid content of 20 to 60% by weight is obtained.

The aqueous resin dispersion of the present invention may contain a colorant such as a dye or a pigment, a filler or the like, and a coating material for resin, leather, metal, wood, ceramic, mortar, concrete, silica plate, etc. It can be used as a binder for paints, paper processing agents, fiber processing agents and the like.

[0023]

The present invention will be described below with reference to examples. In the examples, “part” means “part by weight” and “%” means “% by weight”.

Example 1. Stirrer, thermometer, dropping funnel,
A reaction vessel equipped with a reflux condenser is charged with the amount of the reaction kettle shown in Table 1 and saturated with nitrogen gas. The amounts of drops in Table 1 are mixed in advance. After raising the internal temperature to 65 ° C., a reaction kettle amount of a polymerization initiator was added, and after 5 minutes, dropping was started. The dropping amount was dropped in 3 hours, the mixture was heated and aged at 80 ° C. for another 2 hours, cooled, and adjusted to pH 7 to 8 with ammonia. A resin dispersion having a solid content of 31.0%, a viscosity of 210 cps and a particle diameter of 53 nm was obtained.

[0025] Table 1 Raw material name total amount kettle weight dropping weight ethylene monomer methyl 170 0 170 butyl acrylate methacrylic acid 120 0 120 acrylic acid 10 0 10 reactive emulsifier Ramuteru S-180 30 (5%) 15 15 Polymerization initiator t-Butylbenzoate 3 0.5 2.5 Sodium erythorbate 1 0.2 0.8 Ion-exchanged water 666 384.3 281.7 ───────────────── ───────────────────── () indicates the ratio to the monomer. Ramtel S-180: Reactive emulsifier manufactured by Kao Corporation (active ingredient 50%)

Examples 2 to 6 In the same manner as in Example 1, resin dispersions were obtained by changing the types and amounts of the ethylenic monomer, reactive emulsifier and chain transfer agent.

[0027] Table 2 implementation example raw materials name 2 3 4 5 6 ethylenic monomer methyl methacrylate 90 150 170 170 170 ethyl acrylate 145 butyl acrylate 120 120 120 2-ethylhexyl acrylate 162 Styrene 45 acrylic acid 2 8 10 10 Methacrylic Acid 5 Human Doxyethyl Methacrylate 1 Acrylamide 2 Reactive Emulsifier *** Ramtel S-180 18 (3%) 30 (5%) 30 (5%) Eleminol JS-2 63 (8%) Aqualon HS-10 15 (5%) Polymerization initiator t-butyl benzoate 3 3 3 3 3 sodium ersorbate 1 1 1 1 1 1 ion exchanged water 678 633 681 666 666 ─ ──────────────── ──────────────── * 6 parts of reactive emulsifier (20% of the total amount) was charged into the reaction vessel ** Reactive emulsifier 21 parts (70% of the total amount) were charged in a reaction kettle Ereminol JS-2: Sanyo Chemical Co., Ltd. reactive emulsifier (38% active ingredient) AQUARON HS-10: Daiichi Kogyo Seiyaku Co., Ltd. reactive emulsifier (active ingredient 98) %)

Comparative Examples 1-5 Examples using a non-reactive emulsifier (Comparative Example 1), an example using a small amount of a reactive emulsifier (Comparative Example 2), an example using a large amount of a reactive emulsifier (Comparative Example 3). ), An example in which the amount of the reactive emulsifier charged in the reaction kettle was small (Comparative Example 4) and an example in which an inorganic polymerization initiator was used (Comparative Example 5), a resin dispersion was produced according to Example 1.

[0029] Table 3 comparisons example raw materials Name 1 2 3 4 5 ethylenic monomer methyl methacrylate 170 170 170 170 100 Butyl acrylate 120 120 120 120 120 Acrylic acid 10 10 10 10 10 reactive emulsifier * Ramuteru S -180 6 (1%) 72 (12%) 30 (5%) 30 (5%) Non-reactive emulsifier Sannol NES 50 (5%) Polymerization initiator t-butylbenzoate 3 3 3 3 Sodium ersorbate 1 1 1 1 1 Ammonium persulfate 3 Sodium bisulfite 1 Ion-exchanged water 646 690 624 666 666 ───────────────────────────────── * 1.8 parts (6%) of the reactive emulsifier was charged to the reaction kettle. Sannor NES: Lion's anionic emulsifier (30% active ingredient)

A paint was prepared using the water-based resins obtained in Examples and Comparative Examples, a coating film was prepared, and water resistance was measured.

Test method 1. Preparation of paint Stir the mixture according to the following formulation for 30 minutes with Sun Middle,
After defoaming under reduced pressure, it was subjected to the test. Paint formulation part (1) Aqueous resin dispersion obtained in Examples or Comparative Examples 170 (2) Taipaque R-930 (titanium oxide manufactured by Ishihara Sangyo Co., Ltd.) 45 (3) Emulgen 909 (dispersant manufactured by Kao) 1 ( 4) Ethylene glycol 5 (5) Primal ASE60 (a thickener manufactured by Nippon Acrylic Co., Ltd.) 1 (6) Butyl carbitol 5 (7) Ammonia water 0.2 to 0.5 (8) Water 12.5 to 12.8

2. Preparation of coating film The coating material obtained in the above 1 was applied to a glass plate with a brush to a thickness of 0.
After coating it to 5 mm and leaving it at room temperature for 7 days,
It was submitted to the test.

3. Test Method for Water Resistance The glass plate obtained in the above 2 was immersed in warm water at 40 ° C. for 30 minutes. After removing from warm water, adhering water is removed with gauze, and the degree of whitening is visually judged. Judgment Criteria 5: Good (no whitening at all) 1: Poor (some noticeable whitening on the entire surface)

The physical properties of the materials obtained in each example are shown in Tables 4 and 5 below.

[0035]

[0036]

The method for producing the aqueous resin dispersion of the present invention comprises:
Since the technical feature is that a part of the reactive emulsifier is added to the reaction kettle and an organic polymerization initiator is used, the dispersion stability of the resin particles during production is good and the resin particles melt in the polymerization kettle. Cohesive particles are not formed and attached to the reaction kettle. Further, fine particles having an average particle diameter of 25 to 100 nm can be stably obtained. Therefore, the aqueous resin dispersion can be obtained as a high solid content. Further, it has an advantage that the kind of the monomer used is not limited because the stability at the time of polymerization is good. By applying the aqueous resin dispersion obtained in the present invention to a coating material, a coating film having excellent water resistance can be formed.

Claims (1)

(57) [Claims] 1. A radically polymerizable ethylenic monomer 1
In a method for producing an aqueous resin dispersion, wherein 100 parts by weight of emulsion is subjected to emulsion polymerization in the presence of 2 to 10 parts by weight of a reactive emulsifier, water, 0 to 70% by weight of the monomer, and 10 to 10 parts of the reactive emulsifier.
In a reaction kettle containing 80% by weight, 30 to 1 of the above monomer is added.
A method for producing an aqueous resin dispersion, characterized in that a mixture containing 00% by weight, 20 to 90% by weight of the above reactive emulsifier, and water is added dropwise to carry out radical polymerization with an organic polymerization initiator.