JPS6042249B2 - Method for producing aqueous polymer dispersion - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention deals with the production of α,β-ethylenically unsaturated monomers having sulfonic acid substituents and other α,β-ethylene The present invention relates to a method for producing an aqueous polymer dispersion by radical copolymerization with a sexually unsaturated monomer.

More specifically, the present invention provides various processing methods that produce films with low foaming, excellent pigment miscibility, and good water resistance.
The present invention provides a method for producing an aqueous dispersion useful in coatings and the like. Conventionally, aqueous dispersions of various polymers,
In other words, emulsion polymers are widely used in fields such as paints, adhesives, and textile processing, and because the dispersion medium and diluent are water, there is no risk of fire, and they are not harmful like organic solvents. Recently, its usefulness has been attracting more attention.

All of these emulsions often contain low-molecular-weight emulsifiers such as various surfactants in order to maintain the polymerization reaction during emulsion polymerization and the stability of the produced emitter resin. However, such emulsifiers may be liberated in the aqueous phase of the emulsion, causing foaming and reducing the efficiency of handling operations, or may cause defects such as pinholes in the paint film when used for painting, etc. is often recognized. Also, emulsifiers, due to their hydrophilic properties as well as surfactant abilities, exhibit the serious drawback of reducing the water resistance of films formed from emulsions. On the other hand, polyvinyl acetate or vinyl acetate copolymer emulsions are well known as emulsions obtained without using such emulsifiers, but instead of using emulsifiers, protective colloids such as polyvinyl alcohol, fiber-based ethers, etc. The use of water-soluble polymeric substances is essential.

Since such emulsions contain protective colloids, the water resistance of the film is reduced in the same way as those containing emulsifiers, and furthermore, since they do not contain emulsifiers, they have the disadvantage that the miscibility of pigments, fillers, etc. is extremely poor. Recently, in order to improve the above-mentioned drawbacks, emulsification has been developed using a water-soluble or alkali-soluble oligomer obtained by reacting an alkyl mercaptan with an α,β-monounsaturated ethylenically monomer instead of a conventional emulsifier. It is recognized in Japanese Patent Publication No. 47-34832 that polymerization occurs.
When these oligomers are used, a film with excellent water resistance and strength can be obtained, and the emulsion has low foaming properties, so the above-mentioned drawbacks can be improved to some extent. Ru. However, such emulsions still have poor pigment dispersibility, and are not fully satisfactory for applications such as paints where various compounds are added and mixed, and miscibility and formulation stability are not sufficient. Emulsifiers have to be added in significant amounts to improve it. For this reason, it foams like a conventional emulsion,
Problems such as decreased water resistance remain unsolved. As a result of intensive research, the present inventors aimed to improve such drawbacks and provide an emulsion with excellent durability, good pigment miscibility and stability, and low foaming when applied to various uses. In the presence of a water-soluble or alkali-soluble oligomer having an alkyl sulfide end group with a molecular weight of 200 to 5000 obtained by the reaction of a mercaptan and an α,β-ethylenically unsaturated monomer, α,β-monomers having sulfonic acid substituents are prepared. 0.1 to 10% by weight of one or more ethylenically unsaturated monomers and 90 to 99% by weight of one or more ethylenically unsaturated monomers. The present invention was completed by carrying out radical copolymerization with heel weight% in an aqueous medium. The emulsion obtained in this way has less foaming because it does not contain conventional emulsifiers, and it also has good pigment miscibility and stability because it is stabilized by sulfonic acid groups chemically bonded in the polymer. It provides a film with excellent strength and extremely few defects in water resistance, adhesion to weather-resistant substrates, etc. caused by conventional emulsifiers. The oligomer used in the present invention has a general formula (wherein R has 5 to 2 carbon atoms)
The alkyl groups of 0, Rl, R2, R3, R4, X and Y represent nonpolar or polar addition groups, and at least one of these is a strongly polar group.

The sum of a<15b is 2 to 50. ) with an alkyl sulfide end group having a molecular weight of 200 to 5
There are 000 water-soluble and alkali-soluble types. Such oligomers include, for example, reaction products of alkyl mercaptans with acrylic acid, methacrylic acid, and their alkyl, hydroxyalkyl, amides, acrylonitrile, α-methylenecarboxylic acid sulfoesters, and the above (
1) The formula shown in the formula is 1, and a general-purpose product is Polywet KX-3 or K, a product of Uniroyal in the United States.
X-4 is mentioned.

The amount of the oligomer used in the present invention is 0.1 to 10 parts by weight, particularly preferably 0.2 to 5.0 parts by weight, based on 10 parts of the total monomers used for copolymer synthesis. If the amount is less than 0.1 part by weight, the stability during emulsion polymerization will be poor and problems such as the formation of aggregates will occur.

Further, if the amount exceeds 1 part by weight, undesirable phenomena such as excessive thickening of the system and a tendency for the resulting emulsion film to decrease in water resistance occur. Examples of the α,β monoethylenically unsaturated monomer having a sulfonic acid substituent (hereinafter referred to as a sulfonic acid substituent-containing monomer) used in the present invention include vinyl aromatic sulfones such as vinylbenzenesulfonic acid. Mention may be made of α-methylenecarboxylic acid sulfoesters such as 2-sulfoethyl or 2-sulfopropyl of vinylsulfonic acid and acrylic acid or methacrylic acid, and their ammonium salts or metal salts;
Amides and salts thereof having a sulfozoic acid group such as -sulfopropylacrylamide can also be used. The above-mentioned sulfonic acid substituent-containing monomer is used in an amount of 0.1 to 10.0% by weight, particularly 0.2 to 10.0% by weight based on the total monomers of the polymer component.
5. It is preferable to use 1% by weight; if the amount is less than 0.1% by weight, the pigment dispersibility will be insufficient, and if the amount is more than 1% by weight, it will reduce the water resistance of the film, which is undesirable. .

If the amount is more than 1% by weight, it is not preferable because it reduces the water resistance of the film.

In addition, these sulfonic acid substituent-containing monomers can be used with other α, β
One or more types are selected and used depending on the type of monoethylenically unsaturated monomer (hereinafter referred to as other unsaturated monomer). Other unsaturated monomers that are the main components of the polymer include acrylic monomers such as acrylic acid alkyl esters and methacrylic acid alkyl esters, unsaturated nitriles such as acrylonitrile and methacrylonitrile,
Aromatic vinyl compounds such as styrene and α-methylstyrene, fatty acid vinyl esters such as vinyl acetate and vinyl propionate, crotonate esters such as methyl crotonate and ethyl crotonate, maleic acid, fumaric acid, and itacon. Examples include monoesters or diesters of unsaturated dibasic carboxylic acids such as acids, vinyl halides such as vinyl chloride, vinylidene chloride, etc., α-olefins such as ethylene and propylene, etc., and are suitable for desired uses. , one type or two or more types are selected depending on the purpose. Furthermore, in addition to the above-mentioned monomers, it is also possible to use monomers having reactive polar groups, such as acrylic acid, methacrylic acid, crotonic acid, itaconic acid, maleic acid, and fumaric acid. Saturated acids or salts thereof, unsaturated acid amides or derivatives thereof such as acrylamide, methacrylamide, N-methylolacrylamide, N-methylolmethacrylamide, diacetone acrylamide, etc., unsaturated acids such as hydroxyalkyl acrylate, hydroxyalkyl methacrylate hydroxyalkyl ester of
Epoxy group-containing unsaturated monomers such as glycidyl acrylate and glycidyl methacrylate are used, and diarynophthalate, divinylbenzene, allyl acrylate, allyl methacrylate, and trimethylol are used to internally crosslink the polymer. Monomers having two or more unsaturated bonds in one molecule, such as propane trimethacrylate, can also be copolymerized in some cases.

The aqueous dispersion, i.e., copolymer emulsion, of the present invention comprising the above-mentioned components can be easily obtained by opening a radical-generating catalyst in an aqueous medium in the presence of the above-mentioned oligomers and carrying out radical copolymerization. . The details of the manufacturing method are not particularly limited, but the entire amount or most of the oligomer and sulfonic acid substituent-containing monomer are charged into the reaction system at the initial stage of polymerization, and the remaining monomer and oligomer are It is preferable to add it dropwise into the reaction system as the polymerization progresses. It is also possible to charge the entire amounts of both at the same time and allow them to react. As the radical generating catalyst used here, any catalyst that is generally used in emulsion polymerization can be used, such as water-soluble peroxides or persulfates such as hydrogen peroxide, potassium persulfate, and ammonium persulfate. Alternatively, organic peroxides such as t-butyl hydroperoxide and cumene hydroperoxide, or azo compounds such as azobisisobutyronitrile may be used, and two or more of these may be used in combination. Furthermore, known redox catalysts in combination with reducing agents and/or metal ions such as iron ions can also be used. The amount of catalyst used may be the same as that used in conventional emulsion polymerization, but
Usually, 0.05 to 5 parts by weight is suitable for 100 parts by weight of the total monomers. In addition, the reaction temperature during polymerization is O to 100°C.
1, preferably 20 to 90°C, is suitable. The aqueous polymer dispersion obtained in the present invention has a solid content of 65% by weight.
Although it can be used in any amount, it is generally preferable to adjust the amount to 30 to 60% by weight. Such adjustment can be easily carried out by adjusting the amount of water used during the production of the polymer dispersion. In addition, the pH of the dispersion is preferably maintained at 5 to 10 to prevent the formation of aggregates during the reaction, and in addition, the pH of the product is adjusted to 5 to 10, preferably 6 to 10 for stability. It is more suitable for improving. P
To adjust H, use aqueous ammonia, soda carbonate, soda bicarbonate,
This can be easily carried out by appropriately adding a base or salt such as caustic soda or caustic potash, or an amine such as triethylamine or triethanolamine before, during or after the polymerization. Furthermore, the production of the aqueous polymer dispersion in the present invention is carried out by conventional emulsion polymerization.
At that time, it is also possible to adjust the degree of polymerization by using a chain transfer agent, and in some cases, a surfactant and/or
Alternatively, a protective colloid can also be used in combination.

As surfactants and protective colloids, all those conventionally used in emulsion polymerization can be used, and they are used as appropriate before, during, and after polymerization, but the amounts used are as described above. A plasticizer and/or a volatile film-forming agent may be added to the aqueous polymer dispersion of the present invention as desired for use in the application. It is also possible to add other compounding agents such as antifreeze agents, preservatives, antibacterial agents, rust preventives, buffering agents, various water-soluble resins, crosslinking agents, pigments, fillers, and aggregates.

The aqueous polymer dispersion of the present invention as described above has less foaming than dispersions obtained by conventional emulsion polymerization.
The produced film has excellent durability such as water resistance, weather resistance, and adhesion.
In addition, it has sufficiently satisfactory characteristics in terms of pigment miscibility, miscibility with various compounding agents, stability, etc., so it can be used in various coating agents such as paints, adhesives, paper processing agents, fiber processing agents, etc. Extremely useful for a wide range of applications.

Examples of the present invention are shown below, but the present invention is not limited thereto.

All parts and percentages shown in the examples are based on weight unless otherwise specified. Example 1, Comparative Examples 1 and 2 The following raw materials were charged into a reaction vessel equipped with a stirrer, a reflux condenser, and a thermometer, and dissolved.

Deionized water 547 parts Polywet KX-4 (product of Uniroyal, USA: molecular weight 1400)
~1500 potassium salt of alkyl sulfide-terminated oligomer...solid content 45%) 11.1 Sodium vinylbenzenesulfonate 5NaHC0310 Next, the air in the reaction vessel was replaced with nitrogen gas, and 7 parts of ethyl acrylate, 28 parts of styrene, and A monomer mixture containing 1 part of acrylic acid was charged, 4 parts of potassium persulfate and 4 parts of sodium metabisulfite were added, and the temperature was slowly raised to 50'C.

At the start of the reaction, the inside of the reaction system had a translucent emulsion. Subsequently, while maintaining the temperature at 50°C, 280 parts of ethyl acrylate and 11 parts of styrene were further added. , a solution of a monomer mixture of 4 parts of acrylic acid and 1 part of potassium persulfate dissolved in a portion of deionized water, and a solution of 1 part of sodium metabisulfite dissolved in deionized water were prepared, respectively. for 3 hours,
Other solutions were added dropwise into the reaction system over 3.5 hours to carry out polymerization. After the dropping was completed, the temperature was raised to 60° C., maintained at this temperature for 1 hour, cooled to room temperature, and passed through a 100-mesh wire mesh. At this time, the amount of aggregates that did not pass through the 100-mesh wire mesh was less than 0.1% (ratio to the dispersion produced), and the amount of aggregates produced during the reaction process was extremely small. The aqueous polymer dispersion thus obtained had a non-volatile content of 45.1%,
Viscosity 750CpS (Measured at 25℃ with Burckfield viscometer: rotor No. 3, 60r″Pm), PH
It was 6.3 (measured with a glass electrode PH meter).

In addition, in order to compare with the above composition, the same composition as in Example 1 was used except that sodium vinylbenzenesulfonate was omitted and that the emulsifier was replaced with sodium dodecylbenzenesulfonate instead of Polywet KX-4. A dispersion liquid was obtained.

Table 1 shows the results of comparing various physical properties with the dispersion of Example 1 using the former as Comparative Example 1 and the latter as Comparative Example 2. <
Test method〉 Non-volatile content (%)...About 1 y of sample is accurately weighed, dispersed in 5 cc of water, dried with hot air at 105 to 110°C for 1.5 hours, and the remaining content is weighed to calculate the non-volatile content %. .

Viscosity (Cps) - Measured at 25°C with a Bruckfield rotational viscometer at 60 rpm.

PH...Measure with a glass electrode PH meter.

Surface tension (Dyrle/C!RL)...The sample was diluted with distilled water to a resin concentration of 5%, and the temperature was adjusted to 25°C.
Measured using a Duneuy surface tension meter. Foaming rate (volume %)・
... Dilute the sample with distilled water to a resin concentration of 5%,
Pour 50ml into a 100ml graduated cylinder, seal it with a comb stopper, shake the graduated cylinder up and down at a rate of 1 round trip per second, read the height of the foam after it has stood still for 5 minutes, and calculate the foaming rate (based on the original sample volume). (contrast).

. Hereinafter, it will simply be expressed as a percentage. Minimum film-forming temperature (°C): Measured using a temperature gradient heating plate L-type minimum film-forming temperature tester.

Film hardness (%): A sample was applied onto a glass plate using a 3n111 applicator, and heated at 23°C and 65% R. H. After drying at 2411 Terama, measured using a Swerdrocker hardness tester (compared with standard glass plate as 100) Film water resistance...
The coating was applied to a glass plate in the same manner as for film hardness, and the resulting product was immersed in water for 3 days to observe changes in the state of the coating.

0... No re-emulsification and no detachment Δ...
・There is some re-emulsification and desorption×・・・Re-emulsification and desorption are significant.Alkali resistance of the film…A glass plate coated specimen similar to the film water resistance test was placed in a 5% NaOH aqueous solution for 3 days. Immerse it and observe the change in condition.

Judgment criteria are the same as for film water resistance. Pigment miscibility...
Add pigments and other additives to the test dispersion in the following proportions.

<Formulation> ． - Judgment criteria for observing the condition of this blend> 0: There are no aggregates in the blend, and there is a slight change in viscosity after being left at 50°C for an hour.

Δ: Slight aggregates are observed in the formulation, or a change in viscosity is observed after being left at 50°C for ■ hours.

×: Agglomerates are observed in the formulation, or the viscosity changes significantly after being left at 50°C.

××・・・Does a large amount of aggregates occur in the compound?
Or it aggregates during blending. As is clear from the above table, the aqueous polymer dispersion of the present invention had high surface tension, low foaming, excellent water resistance and alkali resistance, and good pigment miscibility. .

Example 2, Comparative Examples 3 to 5 20 parts of a potassium salt of an oligomer with a molecular weight of about 1200 obtained by the reaction of 1 m01 of t-dodecyl mercaptan, 7 m01 of acrylonitrile, and 7 m0 I of methacrylic acid, 6 parts of sodium vinylsulfonate, 38 parts of NaHCO, and deionized Four parts of water were charged and dissolved in a reaction vessel equipped with a stirrer, a reflux condenser, and a thermometer, and then the air in the reaction vessel was replaced with nitrogen gas. Add 4.5 parts of potassium sulfate and heat to 70°C.
The temperature slowly rose.

At this time, the inside of the reaction system exhibited a translucent emulsion and polymerization was initiated. Subsequently, while maintaining the temperature at 70'C, a solution of 355 parts of vinyl acetate, a monomer mixture of butyl acrylate 9(2), and 1.5 parts of potassium persulfate dissolved in 60 parts of deionized water was added. The latter was added dropwise after 3.5 hours, added to the reaction system, and polymerized. 8 more after the completion of dripping
The temperature was raised to 0° C. and maintained at this temperature for 1 hour, then cooled to room temperature and filtered through a 100 mesh wire mesh. At this time, the amount of aggregates that did not pass through the 100 mesh wire mesh was 0.1% (ratio to the produced dispersion liquid)
The amount of aggregates produced during the reaction process was extremely small. The aqueous polymer dispersion thus obtained had a nonvolatile content of 50.5%, a viscosity of 8500 CpS (measured at 25°C with a Burckfield viscometer: rotor No. 4, Xl2r'Pm), and a pH of 5.6 (glass (measured with an electrode PH meter). In addition, in order to compare with the above dispersion, a solution in which sodium vinyl sulfonate was excluded and a solution in which sodium lauryl sulfate was used as the emulsifier for the entire potassium salt of the oligomer were reacted in the same manner as in Example 2, and water dispersion was obtained. I got the liquid.

The former was used as Comparative Example 3, and the latter was used as Comparative Example 4, and the various properties were compared with the dispersion of Example 2. The results are as shown in Table 2. Furthermore, for comparison, various properties of Boncoat 620 (manufactured by Dainippon Ink and Chemicals Co., Ltd.), which is a conventional commercially available vinyl acetate-acrylic acid ester copolymer emulsion, are also listed in Table 2 as Comparative Example 5. <Test method> Non-volatile content, viscosity, PHL surface tension, foaming rate, minimum film forming temperature...Same pigment compatibility as in Table 1...
...The test dispersion was adjusted to have a non-volatile content of 45% with distilled water, and then the same procedure as in Table 1 was carried out.

Judgment criteria are the same as in Table 1. Color development... 4 parts for 1 (1) part of the pigment mixture to be subjected to the pigment compatibility test
Phthalocyanine Blue J (Dainippon Ink & Chemicals Co., Ltd.)
Co., Ltd. product) and mix well, then apply the resulting blue mixture on a straight plate with a brush and compare the shade of blue.

<Judgment criteria> 0...Exhibits a pale blue color.

Δ...Exhibits a blue color intermediate between O and ×.

×......Exhibits a pale blue color. Paint film water resistance/
...The condition of the paint film after applying the pigment mixture prepared in the pigment compatibility test twice on a straight plate with a brush, drying it at 23°C for 5 days, and immersing it in water at 23°C for 2 weeks. Find out.

<Judgment criteria> 0... No re-emulsification, softening, or falling off Δ...
...Some re-emulsification, softening, and shedding ×...
Re-emulsification, softening, and falling off.Alkali resistance of coating film...
A sample prepared in the same manner as in the case of the paint film water resistance test was
The condition of the coating film after being immersed in a 5% NaOH aqueous solution at .degree. C. for 2 weeks is observed and judged based on the condition.

Judgment criteria are the same as for paint film water resistance. Paint film wash resistance...
...The pigment formulation to be subjected to the pigment compatibility test was applied onto a faded PVC black sheet using a 101T) i1 applicator, and after drying for 7 days, a cleaning solution (15 parts of soap, 1 part of polishing sand) was applied. , 85.5 parts of water) while dropping the load 4.
Wash with a 50y brush and measure the number of wears until the paint film peels off.

As described above, the dispersion of the present invention exhibits excellent properties such as low foaming, excellent pigment miscibility, and good water resistance and alkali resistance of the paint film of the pigment blend (paint). It was hot.

Example 3, Comparative Examples 6-7 Oligomer W part with a molecular weight of about 2300 obtained from the reaction of lauryl mercaptan 1m0I1 methyl methacrylate 8m01, methacrylic acid sodium salt 4m01, and 2-sulfoethyl methacrylate sodium salt 4m01, 2
- 25 parts of sodium salt of sulfoethyl methacrylate,
12.5 parts of 25% aqueous ammonia and 495 parts of deionized water
After dissolving the mixture in a reaction vessel equipped with a stirrer, reflux condenser, and thermometer, and replacing the air in the reaction vessel with nitrogen gas,
23 parts of butyl acrylate, 26 parts of methyl methacrylate
1 part of methacrylic acid, 4 parts of 30% hydrogen peroxide, 4 parts of sodium sulfooxylate formaldehyde, and 0.2 parts of a 1% ferrous ammonium sulfate aqueous solution were added, and the mixture was heated at 35°C. gradually heated up to.

Subsequently, while maintaining the temperature at 352C, a solution prepared by diluting a monomer mixture of 207 parts of butyl acrylate, 234 parts of methyl methacrylate, and 9 parts of methacrylic acid, and 1 part of 30% hydrogen peroxide with one part of deionized water, and a sulfonate solution were added. A solution of 1 part of xylate formaldehyde dissolved in deionized water was prepared, and the monomer mixture was added dropwise over 3 hours, and the other solutions were added dropwise over 31 hours, and then added to the reaction system to carry out polymerization. After the dripping is finished,
The temperature was further raised to 45°C, held at this temperature for 1 hour, then cooled to room temperature and placed in a 100 mesh wire mesh. passed. At this time 1
The amount of aggregates that did not pass through the 00 mesh wire mesh was 0.1% or less (ratio to the produced dispersion liquid), and the amount of aggregates produced during the reaction process was extremely small. The aqueous polymer dispersion thus obtained had a nonvolatile content of 49.9% and a viscosity of 1800111PS (
Burtskfield viscometer: Rotor No. 3.X6
Or'Pm at 25° C.) and pH 8.5 (measured with a glass electrode PH meter). In addition, in order to compare with the above dispersion, we reacted in the same manner as in Example 3 except that the sodium salt of 2-sulfoethyl methacrylate was excluded, and in which the entire amount of the above oligomer was replaced with sodium dodecylbenzenesulfonate as an emulsifier. , a dispersion was obtained.

The former was used as Comparative Example 6, and the latter was used as Comparative Example 7, and the physical properties were compared with those of the dispersion of Example 3. The results are shown in Table 3. Test method> Nonvolatile content, viscosity, PH, surface tension, foaming rate, minimum film forming temperature, film hardness, film water resistance, film alkali resistance...
...Same as in Table 1.

Pigment miscibility: The test dispersion is blended with pigments and other additives in the proportions shown below. Mixture> Observe the condition of the above mixture.

The criteria are the same as for pigment compatibility in Table 1. Steel plate paint film physical properties...Polished mild steel plate (JIS-3141-B
) to NC. The pigment formulation to be tested for pigment compatibility test was applied using a 5O percoater and dried for 1 hour in a hot air dryer at 80°C.
After drying and further drying at room temperature for 3 days, the following tests were conducted.

A. Impact resistance (C77): A steel ball of 112φ" x 500 da is dropped using a DuPont impact tester, and the height without scratching the coating is displayed. Adhesion (%)...
・Make 10 squares in the paint film with a knife, apply cellophane tape, peel it off, and display the remaining rate of the paint film.Acid resistance: 5% sulfuric acid on the paint surface. The aqueous solution is dropped, a glass capsule is placed over the coating, and changes in the state of the coating film are observed after 1 hour.

<Judgment Criteria> 0: No change in coating film condition Δ: Slight discoloration and traces of swelling are seen in the coating film x: Discoloration, swelling, and elution of the coating film Remarkable alkali resistance...Apply 5% NaOH aqueous solution on the painted surface.
Drop it, cover it with a glass capsule, and observe the state of the coating film 1 hour later.

Judgment criteria are the same as for acid resistance. Salt spray resistance...
...A test specimen with a cross cut made with a knife in the coating film is placed in a salt spray tester for n hours, and then the state of rust is observed.

<Judgment criteria> 0: No rust Δ: Slight rusting ×: Significant rust on the entire painted surface Example 4 Oligomer used in Example 2 15 parts of potassium salt, 10 parts of sodium sulfopropyl methacrylate, 5 parts of 25% aqueous ammonia, and 570 parts of deionized water were charged into a reaction vessel equipped with a stirrer, reflux condenser, and thermometer, dissolved, and then the air in the reaction vessel was charged. was replaced with nitrogen gas, and ethyl acrylate 24
．． A monomer mixture of 5 parts of butyl acrylate, 20 parts of styrene, and 0.5 parts of acrylic acid was charged, and further 4 parts of ammonium persulfate and 4 parts of sodium metabisulfite were added, and the temperature was gradually raised to 50°C.

At this time, the inside of the reaction system had a translucent emulsion. Subsequently, while maintaining the temperature at 50°C, further dissolve a monomer mixture of 240.5 parts of ethyl acrylate, 45 parts of butyl acrylate, 1 part of styrene, and 4.5 parts of acrylic acid, and 1 part of ammonium persulfate in a portion of deionized water. The monomer mixture was added dropwise to the reaction system over a period of 3 hours, and the other solutions were added dropwise over a period of 33 hours. After the completion of dripping, another 60
The temperature was raised to .degree. C., maintained at this temperature for 1 hour, cooled to room temperature, and filtered through a 100-mesh wire mesh. At this time, the amount of aggregates that did not pass through the 100-mesh wire mesh was less than 0.1% (ratio to the produced dispersion liquid), and the amount of aggregates produced during the reaction process was extremely small. The aqueous polymer dispersion thus obtained had a nonvolatile content of 45.5% and a viscosity of 250 CpS (Bruckfield viscometer: rotor No. 2, X6 Orpm at 25°C.
(measured by a glass electrode PH meter) and pH 6.8 (measured by a glass electrode PH meter).

Various properties of this dispersion were measured. The results are shown in Table 4. Example 5 A dispersion was obtained by carrying out the reaction in the same manner as in Example 4 except that 30 parts of the potassium salt of the oligomer was used.

Its various properties were measured and shown in Table 4. Comparative Example 8 A reaction was carried out in the same manner as in Example 4 except that 60 parts of the potassium salt of the oligomer was used. As the polymerization progressed, the dispersion became extremely viscous, making it possible to continue the reaction.

Comparative Example 9 When the reaction was carried out in the same manner as in Example 4 except that the potassium salt of the oligomer was not used, the stability during polymerization was poor, and only 7.5% (
(ratio to produced dispersion liquid).

Further, the dispersion had a strong odor of unreacted monomer. Example 6 A dispersion was obtained by carrying out the reaction in the same manner as in Example 4, except that sodium sulfopropyl acrylate was used in (most) part.

Its various properties were measured and the results are shown in Table 4. Comparative Example 10 A dispersion was obtained by carrying out the reaction in the same manner as in Example 4 except that sodium sulfopropyl acrylate was changed to 6(2).

Its various properties were measured and the results are shown in Table 4. Comparative Example 11 A dispersion was obtained by carrying out the reaction in the same manner as in Example 4 except that sodium sulfopropyl acrylate was not used.

Its various properties were measured and shown in Table 4. Comparative Example 12 In Example 4, 15 parts of Neugen EA-120 (produced by Daiichi Kogyo Seiyaku Co., Ltd.: polyoxyethylene nonyl phenyl ether) and dodecylbenzene were used instead of using the oligomer potassium salt and sodium sulfopropyl acrylate. A similar reaction was carried out using Sorg 1 sulfonic acid to obtain a dispersion.

Its various properties were measured and shown in Table 4. As is clear from Table 4, the dispersion according to the present invention had low foaming, good water resistance and alkali resistance of the film, and good pigment miscibility. Example 7 (emulsifier concurrent dropping method) In Example 1, the composition of the initial charge was changed as follows,
Except that a solution of 45.5 parts of the remaining Polywet KX-2, 2.5 parts of sodium vinylbenzenesulfonate, and 35 parts of NaHCO dissolved in deionized water was added dropwise over a period of 3 hours in parallel with the monomer mixture. A reaction was carried out in the same manner as in Example 1 to obtain a dispersion.

Its various properties were measured and shown in Table 5. Example 8 (Monomer total amount dropping method) Same as Example 1 except that the monomer mixture was not initially charged and the entire amount of monomer was added dropwise over 3 hours while maintaining the reaction system at 50 ° C. A dispersion was obtained by carrying out the reaction.

Its various properties were measured and shown in Table 5. Example 9 (Yamagata two-stage method) 7.5 parts of the potassium salt of the oligomer used in Example 2, 5 parts of sodium sulfopropyl methacrylate, 2.5 parts of 25% aqueous ammonia, and 500 parts of deionized water were mixed with a stirrer,
The mixture was charged into a reaction vessel equipped with a reflux condenser and a thermometer and dissolved.

Next, the air in the reaction vessel was replaced with nitrogen gas, and a monomer mixture of 122.5 parts of ethyl acrylate, 25 parts of butyl acrylate, 1 (1) part of styrene, and 2.5 parts of acrylic acid was charged, and 2 parts of ammonium persulfate was added. .5 parts and 25 parts of sodium metabisulfite were added to start the reaction. At this time, the reaction system generated heat and the temperature rose to 55°C. After that, the reaction system was held at 50°C for 1.5 hours, and then cooled to room temperature.
Further, a solution of 7.5 parts of the above oligomer, 5 parts of sodium sulfopropyl methacrylate, and 2.5 parts of 25% aqueous ammonia dissolved in 1 (4) parts of deionized water was added, and then 122.5 parts of ethyl acrylate was added. , 25 parts of butyl acrylate, 1 (1) part of styrene, and 2.0 parts of acrylic acid.
Charge 5 parts of monomer mixture and add 2.5 parts of ammonium persulfate.
5 parts and 2.5 parts of sodium metabisulfite were added to start the re-thickening reaction. The dispersion was exothermed to 50'C. Thereafter, the temperature was maintained at the same temperature for 1 hour, then raised to 60°C, maintained at this temperature for 1 hour, and then cooled to room temperature to obtain a dispersion. Various properties of this dispersion were measured and shown in Table 5. Example 10 (Modified Yamagata two-stage method) 15 parts of the potassium salt of the oligomer used in Example 2, 10 parts of sodium sulfopropyl methacrylate, 5 parts of 25% aqueous ammonia, and 643 parts of deionized water were mixed with a stirrer, a reflux condenser, The mixture was charged into a reaction vessel equipped with a thermometer and dissolved.

Next, the air in the reaction vessel was replaced with nitrogen gas, a monomer mixture of 245 parts of ethyl acrylate and 5 parts of acrylic acid was charged, and 25 parts of ammonium persulfate and 2.5 parts of sodium metabisulfite were added to start the reaction. did. At this time, the temperature of the reaction system was raised to 60°C. After that, the reaction system was heated to 50'C and 1
．． After holding for 5 hours, it was cooled to room temperature, and then a monomer mixture of butyl acrylate and 200 parts of styrene was added, and 1 part of t-butyl hydroperoxide and 1 part of sulfooxylate formaldehyde were added.
Gradually raise the temperature to 0°C, then 1. After holding for an hour, the temperature was raised to 80°C. After maintaining this temperature for 1 hour, it was cooled to room temperature to obtain a dispersion. Various properties of this dispersion were measured and shown in Table 5. As is clear from Table 5, the dispersion of the present invention exhibits little foaming even when the reaction method is varied.
The coating had excellent properties such as excellent water resistance and alkali resistance, and good pigment miscibility.

Claims (1)

[Claims] 1 Polymer of α, β-ethylenically unsaturated monomers with alkyl sulfide terminal groups and a molecular weight of 200 to 5,000.
0.1 to 10% by weight of one or more α,β-ethylenically unsaturated monomers having sulfonic acid substituents and other α A method for producing an aqueous polymer dispersion, comprising radical copolymerization of 90 to 99.9% by weight of one or more β-ethylenically unsaturated monomers.