JPH0610226B2 - Method for producing synthetic resin emulsion - Google Patents

Description

The present invention relates to a method for producing a synthetic resin emulsion having excellent polymerization stability, electrolyte stability, and mechanical stability, and having a film with good water resistance.

In recent years, styrene-butadiene copolymer emulsion, polystyrene emulsion, styrene-acrylonitrile copolymer emulsion, styrene-acrylic acid ester copolymer emulsion, various acrylic acid ester copolymer emulsions, polyvinyl acetate emulsion, vinyl acetate-acrylic acid Ester copolymer emulsion, vinyl acetate-versatic acid vinyl ester copolymer emulsion, ethylene-vinyl acetate copolymer emulsion,
Synthetic resin emulsions such as vinyl chloride-vinylidene chloride copolymer emulsions and vinylidene chloride-acrylic acid ester copolymer emulsions are widely used in coating agents for fiber-processed paper, various adhesives, paints, and civil engineering fields such as mortar and concrete. Used and plays a very important role industrially.

Generally, when such a synthetic resin emulsion is used for the above-mentioned applications, the electrolyte stability of the emulsion,
Properties such as mechanical stability and water resistance of the film are important problems, and various methods have been proposed in order to further improve these properties such as stability and water resistance of the film.

First of all, in order to improve the electrolyte stability and mechanical stability of the synthetic resin emulsion, a method of changing the type of the emulsifier, a method of increasing the amount of the emulsifier and the like have been generally proposed. However, under these circumstances, these methods are not fundamental solutions because the emulsifier itself deteriorates the water resistance and other properties of the film, which are secondary properties of the synthetic resin emulsion. For example, synthetic resin emulsion obtained by the above method as a vehicle of emulsion paint for the purpose of general architectural coating, building material, factory line coating of boards, etc., paper coating, etc. When using a resin emulsion,
Bubbles are generated due to the emulsifier contained in a large amount in the synthetic resin emulsion, which deteriorates coating workability, and pinholes are generated in the coating film after drying, resulting in loss of appearance due to deterioration of gloss, coating strength, The elongation, water resistance, and moisture resistance are lowered, and further the water resistance and alkali resistance of the coating film are lowered due to the weak water resistance of the emulsifier itself, causing various problems.

Further, when such a synthetic resin emulsion is used as a vehicle for an emulsion paint, there is a drawback that the stability of the paint is lowered and agglomeration is caused due to the incorporation of a large amount of an extender pigment, a coloring pigment, and an inorganic salt such as a dispersant. In order to prevent this drawback, it is usual to add a large amount of emulsifiers and stabilizers to the emulsion during the production of the paint. Of the coating film,
It has always caused various problems such as deterioration in alkali resistance and moisture resistance.

In order to eliminate various deficiencies of conventional synthetic resin emulsions due to the presence of such emulsifiers, a method of copolymerizing an ethylenically unsaturated compound with a polymerizable unsaturated emulsifier having an emulsifying action in an aqueous medium and ethylene. When copolymerizing ethylene with an ethylenically unsaturated compound in the absence of an emulsifier, a method of copolymerizing an alkaline salt of unsaturated acylamide-N-sulfonic acid has been proposed.

However, the synthetic resin emulsions obtained by these methods are not yet sufficiently satisfactory in various stability such as electrolyte stability, mechanical stability, pigment admixture stability, and cement admixture stability. When the resulting synthetic resin emulsion is applied to various paint materials such as emulsion paints, mortar, and concrete, it often causes many problems.

Generally, in the case of producing an emulsion paint, as a recent technique for producing an emulsion paint, a pigment is previously kneaded and dispersed with water for the purpose of simplifying the manufacturing method of the paint, saving labor, and increasing the nonvolatile content of the obtained paint. Using a so-called pigment mill base, while stirring the synthetic resin emulsion at high speed, calcium carbonate, an extender pigment such as clay, and various color pigments such as titanium oxide are added as powders and kneaded.
A so-called dry charge method of dispersing is used.

Therefore, when the synthetic resin emulsion obtained by the above method is used for the dry charge method, the various pigments do not disperse well due to poor stability of the emulsion, resulting in agglomerates or, in extreme cases, coating materials. The whole becomes an agglomerate and becomes a state where it cannot fulfill its function as a paint.

Further, when the synthetic resin emulsion obtained by the above method is used as an admixture in cement materials such as mortar and concrete, the electrolyte stability of the emulsion should not be sufficiently satisfied, so Ca ⁺⁺ , Al ^{+ in the} cement ⁺⁺
The emulsion is apt to be broken by such as, and to prevent this, if a large amount of emulsifier or stabilizer is added to the emulsion, foaming will occur during kneading with cement, and not only the strength of the resulting cement material will be significantly reduced, but also workability will be improved. Will result in

In addition, in order to prevent various troubles due to the lack of various stability of conventional synthetic resin emulsions,
A method of emulsion-polymerizing an ethylenically unsaturated monomer in the presence of a water-soluble polymer and a mercapto compound, a water-soluble polymer and a hydroxyl group in addition to a mercapto group in one molecule,
Or in the coexistence of a compound having at least one selected from the group consisting of an amino group or an etheric oxygen derived from them, a thioetheric sulfur, or a nitrogen or carboxy group or a thiocarboxy group forming a primary to tertiary amine. A method of emulsion polymerization, a method of emulsion polymerization in the presence of a water-soluble polymer and a saturated or unsaturated alcohol, and the like have been proposed.

However, in order to produce a stable synthetic resin emulsion by these methods, a large amount of a water-soluble polymer substance and / or an emulsifier is required, so that the resulting film is extremely poor in water resistance and alkali resistance. When used as a cement material such as mortar, mortar, and various concretes, the water resistance of the coating film and the cement material is extremely poor, and in many cases, a large amount of blisters are generated, or water absorption causes a decrease in strength in many cases.

The present inventors have conducted extensive studies in order to improve the drawbacks of the above-mentioned conventional synthetic resin emulsions. As a result, the radical-polymerizable unsaturated monomer containing no sulfonic acid group or sulfonic acid group has 0.1-10 for saturated monomer
Wt% ethylenically unsaturated sulfonic acid or salt thereof,
The synthetic resin emulsion obtained by emulsion polymerization in the presence of at least one water-soluble polymer selected from the group consisting of 0.004 to 10% by weight of the above unsaturated monomer and hydroxyethyl cellulose and polyvinyl alcohol is stable in polymerization. The inventors have found that the properties are extremely excellent, that the obtained synthetic resin emulsion has excellent electrolyte stability and mechanical stability, and that the water resistance of the film is extremely good, and completed the present invention.

That is, the present invention is to carry out emulsion polymerization of a radically polymerizable unsaturated monomer containing no sulfonic acid group or sulfonic acid group with an ethylenically unsaturated sulfonic acid or a salt thereof in the presence of a water-soluble polymer substance. And a method for producing a synthetic resin emulsion.

In the present invention, an ethylenically unsaturated sulfonic acid or a salt thereof is used in order to improve the water resistance of the synthetic resin emulsion film. However, the electrolyte of the synthetic resin emulsion obtained by only the ethylenically unsaturated sulfonic acid or a salt thereof is used. Stability, mechanical stability, pigment admixture stability, cement admixture stability, etc. are inferior, so a relatively small amount of water-soluble synthetic polymer coexists within the range that does not impair the water resistance of the film. By doing so, the polymerization stability is good, various stability such as electrolyte stability, mechanical stability, pigment admixture stability and cement admixture stability are excellent, and moreover, the water resistance and alkali resistance of the obtained film are excellent. A synthetic resin emulsion having good physical properties can be obtained.

Therefore, when the synthetic resin emulsion produced by the method of the present invention is used as a vehicle for the various emulsion paints or as an admixture of various cement materials, there is no foaming trouble, and the paint has good stability and excellent workability. , And a cement material can be obtained, and the coating film obtained after drying and curing and the cement material have high strength, and are excellent in water resistance, alkali resistance, moisture resistance and waterproofness.

The ethylenically unsaturated sulfonic acid or salt thereof used in the present invention is a copolymerizable one with a radically polymerizable unsaturated monomer containing no sulfonic acid group or sulfonic acid group, and specific examples include: Sulfonated styrene,
Sulfonated unsaturated hydrocarbons such as allyl sulfonic acid and methallyl sulfonic acid and salts thereof, sulfoalkyl esters of acrylic acid or methacrylic acid such as vinyl sulfonate, methacrylic acid sulfoethyl ester and methacrylic acid sulfopropyl ester, and Examples thereof include salts thereof, acrylamidosulfonic acid, 2-acrylamide, 2-methylpropanesulfonic acid and salts thereof, and various alkylallylsulfosuccinic acids and salts thereof. The salt here means an ammonium salt and an alkali metal salt.

The amount of ethylenically unsaturated sulfonic acid or its salt used is
It is 0.1 to 10% by weight, preferably 0.2 to 5% by weight, based on the radical-polymerizable unsaturated monomer containing no sulfonic acid group or sulfonic acid group. If the amount of the ethylenically unsaturated sulfonic acid or its salt used is less than 0.1% by weight, not only the effect of forming stable particles is not sufficient, but also the polymerization rate is low, and aggregates are formed, resulting in poor polymerization stability. On the other hand, if the amount of the ethylenically unsaturated sulfonic acid or its salt used exceeds 10% by weight, the water resistance of the film of the synthetic resin emulsion obtained is insufficient and the intended purpose cannot be achieved.

Further, the water-soluble polymer substance used in the present invention includes at least one selected from the group consisting of hydroxyethyl cellulose and polyvinyl alcohol.

The amount of the water-soluble polymer used is 0.004 to 10% by weight, preferably 0.02 to 2% by weight, based on the radical-polymerizable unsaturated monomer containing no sulfonic acid group or sulfonic acid group.
Is. If the amount of water-soluble polymer substance used is less than 0.004% by weight, the stability of the resulting synthetic resin emulsion such as electrolyte stability and mechanical stability is insufficient, and the amount of water-soluble polymer substance used is less than 10% by weight. If it exceeds, there is a drawback that the water resistance of the film is insufficient.

In the present invention, in addition to the ethylenically unsaturated sulfonic acid or its salt and the water-soluble polymer substance, if necessary, polyoxyethylene lauryl ether, polyoxyethylene nonylphenyl ether, polyoxyethylene sorbitan monostearate, dodecyl. It is possible to use an appropriate amount of nonionic and / or anionic general emulsifiers such as sodium benzene sulfonate and soda salts of various alkyl sulfates.

The radical-polymerizable unsaturated monomer containing no sulfonic acid group or sulfonic acid group used in the present invention may be any emulsion-polymerizable monomer such as styrene and α-methylstyrene. , Aromatic vinyl monomers such as chlorostyrene, vinyl cyanide monomers such as acrylonitrile and matacrylonitrile, methyl acrylate, ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, nonyl acrylate Acrylic esters or methacrylic acid esters such as esters, methyl methacrylate, butyl methacrylate, isobutyl methacrylate, 2-ethylhexyl methacrylate, vinyl halides such as vinyl chloride, vinyl bromide, vinylidene chloride, vinylidene bromide or the like. Vinylidene halides, vinegar Vinyl, vinyl esters such as vinyl propionate, butadiene, conjugated diene monomers such as isoprene, maleic acid esters, unsaturated polycarboxylic acid esters such as fumaric acid esters, acrylic acid,
Unsaturated monocarboxylic acids such as methacrylic acid, unsaturated polycarboxylic acids such as maleic acid, fumaric acid and itaconic acid, unsaturated amides such as acrylamide and N-methylolacrylamide, glycidyl methacrylate, ethylene glycol diacrylate, divinylbenzene. And other polyfunctional monomers. These radically polymerizable unsaturated monomers may be used alone or in admixture of two or more.

As the polymerization initiator, those generally used in emulsion polymerization, for example, ammonium persulfate, potassium persulfate, hydrogen peroxide solution, t-butyl hydroperoxide, permanganate, etc., or a water-soluble oxidizing agent are used. Inorganic salts or organic peroxides, or redox-based catalysts that use a reducing agent such as acidic sodium sulfite, hypo, Rongalit, thiourea, organic oxysalt saccharides, ferrous sulfate, etc. can be used as they are, and the amount used It is the same as in the case of general emulsion polymerization, and is generally 0.1 to 1% by weight based on all monomers. Of course, irradiation with radiation can be used instead of the polymerization initiator.

As the method for producing the synthetic resin emulsion of the present invention, any of the polymerization operations performed in the conventional emulsion polymerization method can be adopted.

The polymerization temperature varies depending on the radical-polymerizable unsaturated monomer containing no sulfonic acid group or sulfonic acid group used, ethylenically unsaturated sulfonic acid or its salt, the polymerization initiator and the cooling capacity of the reaction vessel. Although not determined, it is usually preferable to be in the range of 50 to 90 ° C.

In the emulsion polymerization method of the present invention, in addition to the above-mentioned substances, as a modifier, a neutralizing agent, a water resistance-imparting agent (such as titanyl sulfate), a defoaming agent, a stabilizer, an organic solvent, a plasticizer, an antiseptic agent. It is also possible to add the like.

Hereinafter, the present invention will be described in more detail with reference to examples.

All percentages shown in the following examples are based on weight.

The mechanical stability, electrolyte stability and water whitening resistance of the synthetic resin emulsions obtained in Examples and Comparative Examples were measured according to the following methods.

(1) Mechanical stability It was measured by the Marlon method. That is, 100 g of a synthetic resin emulsion having a known concentration, which had been passed through a 180-degree furnace cloth in advance, was weighed in a Marlon tester container, and a weight of 30 kg, 18
Operate at 00 rpm for 15 minutes. After that, the adhered substances and solidified substances on the wall surface of the rotor and the Marlon tester are washed off in a beaker, passed through a 80th oven cloth, coarse particles in the oven cloth are separated, and dried at 110 ° C. until a constant weight is obtained.

The weight% of the coarse particles and the solidified product is determined by the following formula.

[A: weight of furnace cloth, B: weight of furnace cloth + solidified material, C: sample concentration (%)] Evaluation is good if the solidified amount of the 80th cloth is 0.1% or less.
1% is Δ, and 1% or more is defective.

(2) Electrolyte stability Calcium chloride was added to 100 g of synthetic resin emulsion, and the salt stability of the emulsion was defined as the number of grams of calcium chloride required until the emulsion began to aggregate and separate.

(3) Water-whitening resistance of the film Synthetic resin emulsion was applied on a glass plate with a 5 mil applicator, dried in a room at 20 ° C and 65% RH for 7 days, and then a drop of room temperature water was dropped on the film, Was adhered to a newspaper, the time until the hiragana of the 8-point type could not be read was measured and used as a measure of the degree of water whitening resistance of the film.

Example 1 A reflux condenser, a thermometer, a stirrer, and a dropping funnel were attached to a five-necked flask equipped with a one-necked five-necked flask, and 1 g of sodium pyrophosphate, 5 g of itaconic acid, and 50 parts of sodium alkylallylsulfosuccinate were placed in the flask. % Aqueous solution 2 g, water 1
Charge 80 g, and stir the temperature of the charge liquid to 76 ° C.
I raised it to. To this, 193 g of water, a 10% aqueous solution of polyvinyl alcohol (completely saponified product, polymerization degree 500) 50
g, 50% of sodium alkylallyl sulfosuccinate
A monomer emulsion consisting of 12 g of an aqueous solution, 250 g of acrylic acid 2-ethylhexyl ester and 250 g of styrene and an aqueous solution of 2 g of ammonium persulfate dissolved in 48 g of water were added dropwise by separate dropping funnels over 3 hours and 30 minutes. The temperature in the flask was gradually raised from 76 ° C. to 83 ° C. over 30 minutes after the start of dropping, and thereafter kept at 83 to 85 ° C. as constant as possible until the dropping of the monomer emulsion and the aqueous solution of ammonium persulfate was completed. After dropping the whole amount of the monomer emulsion, the temperature was kept at 83 to 85 ° C. for another hour. Then, after cooling to 30 ° C. or lower, 7 g of ammonia water (28%) was added, and the contents were taken out after stirring for about 20 minutes.

The characteristics of the obtained synthetic resin emulsion and the water whitening resistance of the film are shown in Table 2.

Examples 2 to 6 and Comparative Examples 1 to 3 Radical-polymerizable unsaturated monomer containing no sulfonic acid group or sulfonate group, ethylenically unsaturated sulfonic acid or salt thereof, water-soluble polymer substance and general Polymerization was carried out in the same manner as in Example 1 except that the combination of emulsifiers was changed as shown in Table 1.

The sodium dodecylbenzene sulfonate and polyoxyethylene nonylphenyl ether of Comparative Example 3 were used in place of the sodium alkylallyl sulfosuccinate of Example 1, and they were used only as a monomer emulsifier, and in a flask. It was not added.

Table 2 shows the characteristics of each synthetic resin emulsion obtained under the above conditions and the water whitening resistance of the film.

Examples 7 to 12 and Comparative Examples 4 to 6 Radical-polymerizable unsaturated monomer containing no sulfonic acid group or sulfonate group, ethylenically unsaturated sulfonic acid or salt thereof, water-soluble polymer substance and general Polymerization was carried out in the same manner as in Example 1 except that the combination of emulsifiers was changed as shown in Table 3.

In addition, the sodium dodecylbenzene sulfonates and polyoxyethylene nonylphenyl ethers of Comparative Examples 4 to 6 were used only in the monomer emulsion, and were not added to the flask.

Table 4 shows the characteristics of each synthetic resin emulsion obtained under the above conditions and the water-whitening resistance of the film.

Examples 13 to 14 and Comparative Examples 7 to 11 Radical-polymerizable unsaturated monomer containing no sulfonic acid group or sulfonate group, ethylenically unsaturated sulfonic acid or salt thereof, water-soluble polymer substance and general Polymerization was carried out in the same manner as in Example 1 except that the emulsifier was changed as shown in Table 5.

The sodium dodecylbenzene sulfonate and polyoxyethylene nonyl phenyl ethers of Comparative Examples 7 to 9 were used only in the monomer emulsion and were not added to the flask.

Table 6 shows the characteristics and film performance of each synthetic resin emulsion obtained by polymerization under the above conditions.

Claims (1)

[Claims] 1. A radical-polymerizable unsaturated monomer that does not contain a sulfonic acid group or a sulfonate group is used in an amount of 0.1 to 10% by weight based on the unsaturated monomer, of ethylenically unsaturated sulfonic acid or a salt thereof. , 0.004 to 10 with respect to the unsaturated monomer
A method for producing a synthetic resin emulsion, which comprises emulsion-polymerizing in the presence of at least one water-soluble polymer substance selected from the group consisting of wt% hydroxyethyl cellulose and polyvinyl alcohol.