JPH0453803A - Production of polymer emulsion - Google Patents

Abstract

PURPOSE:To surely obtain a polymer emulsion excellent in miscibility with a water-sol. solvent by allowing a vinyl monomer to undergo an emulsion polymn. in a specific manner in the presence of seed polymer particles while adding the monomer to the polymn. system. CONSTITUTION:In a process for producing a polymer emulsion by allowing a vinyl monomer to undergo an emulsion polymn. in the presence of seed polymer particles while adding the monomer continuously or intermittently to the polymn. system, a water-sol. polymer having a wt.-average mol.wt. of 500-50000 is added to the system continuously or intermittently in the course of polymn. As the monomer, a vinyl monomer radical-polymerizable in an aq. dispersion medium can be used. An example of the particles is a latex contg. polymer particles having a mean diameter of 5000Angstrom or lower, pref. 300-4000Angstrom .

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a method for producing a polymer emulsion in which mono 7- is emulsion polymerized in the presence of a polymer.

[Conventional technology]

Polymer emulsions are generally widely used as paints, fiber treatment agents, paper processing agents, uncoated agents, carpet backing agents, precoated metal coating agents, and the like. It is preferable that such a polymer emulsion has excellent miscibility with water-soluble solvents from the viewpoint of environmental protection, ease of work, and other aspects. In addition, as a matter of course, the polymer particles of polymer emulsion are
It is desirable to have a well-controlled and uniform particle size.

Conventionally, methods for producing polymer emulsions include emulsion polymerization using an aqueous dispersion medium, soap-free emulsion polymerization, or suspension polymerization, and the particle size of polymer particles is not sufficiently controlled. As an effective method for producing a more uniform polymer emulsion, a so-called wet polymerization method in which polymerization is carried out in the presence of seed polymer particles is known.

[Problems that Cohatsu is trying to solve] However, in order to stably perform the desired emulsion polymerization using seed polymer particles, there are various restrictions due to the polymerization mechanism, and there are It is not possible to freely select the type and composition of monomers and the type and amount of emulsifiers or stabilizers used in the monomer composition used, and as a result, polymer emulsions that have excellent miscibility with water-soluble solvents are produced. is quite difficult to manufacture.

For example, polymer emulsions obtained by ionically stabilizing dispersed particles in an aqueous dispersion medium using soap as an emulsifier and carrying out emulsion polymerization in the presence of seed polymer particles have a high miscibility in water-soluble solvents. When mixed with a water-soluble solvent, the instability of the polymer particles causes agglomeration or gelation.

On the other hand, it is also known to use a suspending agent or a stabilizer made of a water-soluble polymer such as polyvinyl alcohol. Such a stabilizer stabilizes the dispersed particles by adsorbing them as a steric protective layer on the dispersed particles in the aqueous dispersion medium.

However, stabilizers that act like a steric protective layer have a larger molecular weight than emulsifiers that act ionicly, and are not fully adsorbed on the surface of dispersed particles, so they cannot be dispersed in an aqueous dispersion medium. Many of these particles exist on their own, separate from particles, and it is easy for the polymerization reaction system to contain a large amount of other particles other than those that should originally exist.As a result, it is difficult to control the particle size of polymer particles. Then,
Moreover, the stability of the dispersed particles in the polymerization reaction system is usually not always sufficient.

Moreover, the resulting polymer emulsion is unstable and has poor miscibility with water-soluble solvents since the particle size of the polymer particles is not sufficiently uniform.

An object of the present invention is to increase the degree of freedom in the polymerization reaction by carrying out the polymerization reaction in a specific manner in a method for producing a polymer emulsion in which a vinyl monomer is emulsion polymerized in the presence of seed polymer particles. To provide a method that can reliably produce a polymer emulsion that generates fewer separate particles, is composed of polymer particles with a well-controlled and uniform particle size, and has excellent miscibility with water-soluble solvents. be.

[Means to solve the problem]

The present invention provides a method for producing a polymer emulsion in which emulsion polymerization is carried out while adding a vinyl monomer continuously or intermittently in the presence of seed polymer particles.
．． 000 water-soluble polymer is added continuously or intermittently.

The present invention will be explained in detail below.

In a typical example of the method according to the present invention, a vinyl monomer is continuously or intermittently supplied to an aqueous dispersion medium in which seed polymer particles are present in an aqueous dispersion medium containing an emulsifier. In the case of emulsion polymerization of the vinyl monomer in the presence of the vinyl monomer, a specific water-soluble polymer is added continuously or intermittently to the polymerization reaction system according to the progress of the polymerization reaction of the vinyl monomer, thereby forming a polymer emulsion. Manufacture.

<Vinyl Monomer> The monomer used in the method of the present invention is a vinyl monomer, and the vinyl monomer is not particularly limited as long as it can be polymerized by radical polymerization in an aqueous dispersion medium. Specifically, the following can be exemplified.

Aromatic hinyl compounds: styrene, α-methylstyrene,
p-methylstyrene, talolostyrene, styrene sulfonic acid, ethylstyrene, vinylbenzene, other aliphatic diene compounds, 1,3-butadiene, inoprene, 1,4-hexadiene, and other ethylenically unsaturated carboxylic acid ester compounds Methyl (
meth)acrylate, butyl(meth)acrylate, 2
-Ethylhexyl(meth)acrylate, Grindyl (
meth)acrylate, lauryl(meth)acrylate,
Hydroquinoethyl (meth)acrylate, N N-dimethylaminoethyl (meth)acrylate, other halogen-based unsaturated compounds Vinyl chloride, vinylitine chloride, vinyl bromide, other organic acid vinyl compounds Vinyl acetate vinylopestearate, other monomers or dicarboxylic acid compounds such as niacrylic acid, methacrylic acid, itaconic acid, maleic acid, fumaric acid, acid anhydrides or monoalkyl esters of these dicarboxylic acids, other monoamide compounds such as niacrylamide, methacrylamide, and others, imprene sulfonic acid Vinyl monomers containing various functional groups such as , 2-acrylamido-2-methylpropanesulfonic acid, and N-methylolmethacrylamide can be used.

The vinyl monomer is added to the polymerization reaction system continuously or intermittently. The rate of addition of the vinyl monomer is not particularly limited and may be appropriately set according to the progress of polymerization. Practically speaking, it is preferable to add it at each point in the polymerization reaction so that the polymerization conversion rate in the polymerization reaction system is maintained at about 50% or more.

The amount of vinyl monomer used is not particularly limited, but for example, 0.1 to 100 times the amount of the seed polymer particles (
weight).

<Polymerization initiator> In the method of the present invention, as the polymerization initiator, for example, water-soluble persulfates, hydrogen peroxide, etc. can be used, and they can also be used in combination with a reducing agent. Examples of the reducing agent include sodium pyrobisulfite, sodium hydrogensulfite, sodium thiosulfate, L-ascorbic acid and its salts, and sodium formaldehyde sulfoxylate.

In addition, oil-soluble polymerization initiators such as 2,2°-azobisisobutyronitrile, 2,2°-azobis(4-methoxy-24-dimethylvaleronitrile), 2,2′-azobis-2,4 -dimethylvaleronitrile, 1.1°-azobis-cyclohexane-1-carbonitrile, benzoyl peroxide, dibutyl peroxide, cumene hydroperoxide, t-butyl hydroperoxide, 3,5.5-)limethylhexanol peroxide Oxide, t-butyl peroxy (2-ethylhexanoate), etc. can be used by dissolving it in a vinyl monomer or an aqueous dispersion medium. Among these, preferred oil-soluble polymerization initiators include cumene hydroperoxide, isopropylbenzene hydroperoxide, azobisisobutyronitrile, benzoyl peroxide, t-butyl hydroperoxide, 3,5.5-) Methylhexanol peroxide, t-butylperoxy (2-ethylhexanoate)
etc. can be mentioned.

The amount of these polymerization initiators to be used is determined depending on the type and amount of the vinyl monomer added, but it is usually preferably 0.05 to 30% by weight of the vinyl monomer.

<Emulsifier> In the method of the present invention, there are no particular restrictions on the emulsifier added to the aqueous dispersion medium, and any emulsifier such as anionic, nonionic, or amphoteric surfactants used in general emulsion polymerization methods may be used. can be used. The amount of anionic surfactant used is usually 0.01 to 3% by weight,
The amount of nonionic and amphoteric surfactants used is usually
It is 0.5 to 5% by weight.

<Seed polymer particles> The seed polymer particles used in the method of the present invention have an average particle diameter of 5000 Å or less, preferably 400 Å or less.
Mention may be made of latexes with 0 to 300 polymer particles. Examples of the material forming the polymer particles include polystyrene, carboxy-modified polystyrene, carboxyl-modified styrene-butadiene copolymer, styrene-butadiene copolymer, styrene acrylic ester copolymer, styrene methacrylic ester copolymer,
Examples include acrylic ester copolymer, methacrylic ester copolymer, carboquine-modified styrene acrylic ester copolymer, carboxy-modified styrene-methacrylic ester copolymer, carboquine-modified acrylic ester copolymer, carboquine-modified methacrylic ester copolymer, vinylidene fluoride copolymer, and the like.

Among the above, examples of acrylic esters include 2-hydroquine acrylate, N-dialkylaminoethyl acrylate, grindyl acrylate, fluoroalkyl acrylate, etc., and examples of methacrylic ester include dialkylaminoethyl methacrylate, fluoromethacrylate, etc. Examples include alkinope 2-hydroxyethyl methacrylate, methacrylic acid grindinope ethylene glycol dimethacrylate, and the like.

The hollow polymer particles used in the present invention may be hollow polymer particles. When hollow polymer particles are used as the hollow polymer particles, it is possible to obtain a polymer emulsion that has excellent miscibility with water-soluble solvents and is useful as a coating agent with a high hiding rate.

The hollow polymer particles used as the soft polymer particles are not particularly limited, and examples include those obtained by the methods described in JP-A-6187734 and JP-A-62-127336. Specifically, it is composed of two layers: 100 parts by weight of a copolymer made of a polymerizable monomer component containing a crosslinkable monomer, and 1 to 100 parts by weight of a different polymer different from this copolymer, and has an outer diameter of 0.05 to 10%. Mention may be made of polymer particles having internal pores whose internal diameter is 0.2 to 0.9 times the external diameter.

Water-soluble polymer> In the method of the present invention, a water-soluble polymer is used in a specific embodiment. This water-soluble polymer improves the dispersibility of the generated polymer particles and prevents agglomeration.
According to the progress of the polymerization reaction of the vinyl monomer, it is added continuously or intermittently to the polymerization reaction system.

Examples of this water-soluble polymer include polyvinylalconope polyacrylate, water-soluble acrylic acid ester copolymer, water-soluble methacrylic acid ester copolymer, styrene-maleic acid copolymer salt, and styrene-acrylic acid copolymer. Examples include coalescent salts, styrene-methacrylic acid copolymer salts, polyacrylamide, polymethacrylamide, polyacrylamide copolymers, and polymethacrylamide copolymers. Among these, partially saponified polyvinyl alcohol, water-soluble acrylic acid ester copolymer,
Water-soluble methacrylic acid ester copolymer, styrene-maleic acid copolymer salt, styrene-acrylic acid copolymer salt,
Preferred examples include salts of carboxylated aromatic vinyl copolymers, such as styrene-methacrylic acid copolymer salts. It is also possible to use solvent-containing water-soluble polymers.

The water-soluble polymer used in the method of the present invention has a weight average molecular weight in the range of 500 to 50.000, preferably in the range of 1.000 to 25.0 OCI. If a water-soluble polymer with a weight average molecular weight of less than 500 is used, the resulting polymer emulsion will have poor miscibility with the water-soluble solvent;
If a water-soluble polymer of greater than 0 is used, the viscosity of the polymerization reaction system will increase, making it difficult to produce a suitable polymer emulsion.

The total proportion of water-soluble polymers used in the process of the invention is between 5 and 60% based on the total amount of vinyl monomers used.
It is preferably 10 to 3% by weight, more preferably 10 to 3% by weight.
It is 0% by weight. If this proportion is less than 5% by weight, the substantial effect of the present invention cannot be obtained, and if it is greater than 60% by weight, the polymer emulsion will have poor water resistance or problems such as the generation of other particles will occur. .

Preferably, the water-soluble polymer is added to the polymerization reaction system at a rate that substantially corresponds to the amount of polymerization conversion of the vinyl monomer. Therefore, when the vinyl monomer is continuously added to the polymerization reaction system, the addition rate of the vinyl monomer per unit time (ratio of the amount of vinyl monomer added per S-position time to the total amount of vinyl monomers)
It is preferable to add the water-soluble polymer at substantially the same addition rate as the vinyl monomer, and when the vinyl monomer is added intermittently, it is preferable to add the water-soluble polymer intermittently in the same manner. In such cases where vinyl monomer and water-soluble polymer are added intermittently,
The number of additions (the number of divided parts) is preferably three or more.

Further, it is preferable that the water-soluble polymer is added at a relatively slow rate initially, and the addition rate is increased over time.

A polymer emulsion is produced in the manner described above. That is, a polymer emulsion is produced by emulsion polymerization of a vinyl monomer in the presence of seed polymer particles, but since a water-soluble polymer is added as the polymerization reaction of the vinyl monomer progresses, the polymer particles that are sequentially produced are The dispersion state is always maintained stably by the water-soluble polymer, and the generation of other particles is reliably suppressed. Furthermore, since this emulsion polymerization is carried out in the presence of seed polymer particles, the particle size of the finally obtained polymer particles is sufficiently controlled and uniform according to the particle size of the seed polymer particles. In particular, as a part of the water-soluble polymer adheres to all the polymer particles, the hydrophilicity of the obtained polymer particles becomes high, and the polymer emulsion has excellent miscibility with water-soluble solvents.

In the above, water-soluble solvents include, for example, diethylene glycol monobutyl ether, ethylene glycol monobutyl ether, ethylene glycol monoethyl ether acetate, diethylene glycol acetate, diethylene glycol monobutyl ether acetate, butyrolactone, diacetone alconope acetonyl acetone, acetone, methyl ethyl ketone, methyl alcohol,
These include ethyl alcohol, isopropyl alcohol, n-butyl alcohol, tetrahydrofuran, triethinopedimethylsulfoquine phosphate, acetamide, and mixtures of two or more of these are also included.

By mixing the polymer emulsion produced by the method of the present invention with the above-mentioned water-soluble solvent together with other necessary additive components, a composition suitably used as a paint or coating agent for boat fishing can be obtained. I can do it.

Therefore, the polymer emulsion according to the present invention can be used as a paint, a fiber treatment agent, a paper processing agent, a floor coating agent, a carpet backing agent, a precoat metal coating agent, etc. by utilizing its properties, and in particular, it can be used as a precoat metal coating agent. It is suitable as an agent.

〔Example〕

Examples of the present invention will be described in detail below, but the present invention is not limited thereto. In addition,
Both "part" and "%" are based on weight, and the average particle diameter of the polymer particles is a value measured using "Nanosizer" (manufactured by Coulter).

Seed polymer particles (a) and (b) and water-soluble polymers (i) to used in the following examples and comparative examples
(1v) was prepared as follows.

<Synthesis of seed polymer particles> Seed polymer particles (a) Styrene 93 parts Methacrylic acid 7 parts t-dodecyl mercaptan 5 parts Sodium dodecylbenzenesulfonate 0.1 part Potassium persulfate 0.5 part Water
150
The above materials were charged in bulk into an autoclave with a capacity of 21 in a nitrogen atmosphere, heated to 75°C with stirring, and polymerized over 6 hours to obtain an average particle size of 0.1.
An emulsion of 5a+ seed polymer particles (a) was obtained. The polymerization stability in this polymerization reaction system is good,
Further, the final polymerization conversion rate was 99.0%.

Seed polymer particles (b) The above seed polymer particles (a) 10 parts styrene
20 parts methyl methacrylate 40 parts divinylbenzene
25 parts methacrylic acid
5 parts Sodium dodenlebenzenesulfonate 0, IB Potassium persulfate 1.5 parts Water
200
The above materials were charged in bulk into an autoclave with a capacity of 2p under a nitrogen atmosphere, heated to 75°C with stirring, and a polymerization reaction was carried out over a period of 6 hours until the average particle size was 0.
An emulsion of 4 μs hollow polymer particles (b) was obtained. The polymerization stability in this polymerization reaction system was good, and the final polymerization conversion rate was 99.0%.

Synthesis of water-soluble polymer> Water-soluble polymer (1) Styrene 37.5 parts Ethyl acrylate 20 parts Methacrylic acid 25 parts Butyl acrylate 175 parts Benzoyl peroxide 70 parts Ethylene glycol monobutyl ether 200 parts In a 2p autoclave under nitrogen atmosphere Ethylene glycol monobutyl ether was charged, the temperature was raised to 5° C. while stirring, and each monomer and polymerization initiator were continuously added over 4 hours to cause a polymerization reaction. The polymerization conversion rate of this polymerization reaction was 97%. The obtained reaction product contains the same number of moles of ammonia and water as the carboxylic acid.
0 parts and neutralized and dissolved to obtain a weight average molecular weight of 70.
A water-soluble polymer (1) of 0 was obtained.

Water-soluble polymer (11) The amount of benzoyl peroxide, which is a polymerization initiator, is 2.
A water-soluble polymer (11) having a weight average molecular weight of 45,000 was obtained by performing the same operation as for water-soluble polymer (1) except that the amount was changed to 0 parts. The polymerization conversion rate of this polymerization reaction was 984%.

Water-soluble polymer (iii) The amount of benzoyl peroxide, which is a polymerization initiator, is 10
．． A water-soluble polymer (iii) having a weight average molecular weight of 300 was obtained by carrying out the same operation as in water-soluble polymer (iii) except that the amount was changed to 0 parts. The polymerization conversion rate of this polymerization reaction was 98.6%.

Water-soluble polymer (1■) The amount of benzoyl peroxide as a polymerization initiator was adjusted to 0.
A water-soluble polymer (1) having a weight average molecular weight of 70,000 was obtained by carrying out the same operation as for the water-soluble polymer (]) except that the amount was changed to 5 parts. The polymerization conversion rate of this polymerization reaction was 95.4%.

In addition, the following water-soluble polymers (v) to (vll) were prepared.

Water-soluble polymer (v) Styrene-acrylic acid copolymer “Joncryl J~62
” (weight average molecular weight 7.000, made by Johnson ■) Water-soluble polymer (vi) N-methylolmelamine "M-3" (weight average molecular weight 50,000, manufactured by Jujutsu 3M ■) Water-soluble polymer (vii) Polyvinyl alcohol Senor GL-03=.

(Weight average molecular weight 3.000, manufactured by Nippon Gosei Kagaku ■) Example 1 Substances other than the vinyl monomer of the following composition (A) were placed in a 110β autoclave under a nitrogen atmosphere and heated to 80°C while stirring. The temperature was raised, and emulsion polymerization was carried out by continuously adding vinyl monomer (total 100 parts) and a mixture of water-soluble polymer (v) 2ON and 50 parts of water at a uniform addition rate over 3 hours.

Thereafter, the temperature was maintained at 80° C. for 2 hours to obtain Polymer Emulsion 1.

Composition (A) (Acrylic composition) Polymer particles (A) IC 1.0 parts Styrene 524 parts Butyl acrylate 320 parts 2-ethylhequinyl acrylate 13.6 parts Methacrylic acid
2.0 parts t-dodenlumel butane
0.5 parts Sodium dodenlebenzenesulfonate 01 parts Potassium persulfate 0.3 parts Water
200
The polymerization stability in polymerization reactions of more than 10% is extremely high,
The final polymerization conversion rate was 990%.

The average particle diameter of the polymer particles of the obtained polymer emulsion 1 was 0.33 parts m, and when this polymer emulsion 1 was observed with an electron microscope, it had a sharp distribution.

Furthermore, the miscibility of this polymer emulsion 1 with water-soluble solvents was evaluated. That is, an appropriate amount of Polymer Emulsion 1 and the same amount of ethylene glycol monoethyl ether acetate were placed in a 100-capacity Erlenmeyer flask, stirred for 5 minutes, and then left at 40°C for 3 hours.
The obtained liquid mixture was applied to a glass plate and the presence or absence of aggregates was observed.

As a result, the presence of aggregates was not observed.

Further, for confirmation, when the liquid mixture was filtered using a 300 mt filter, almost no aggregates were observed.

A similar compatibility test was conducted using n-butyl alcohol as the water-soluble solvent, and similarly no presence of aggregates was observed.

As is clear from the above results, this polymer emulsion 1 has excellent miscibility with water-soluble solvents.

Examples 2 to 4 Three types of polymer emulsions 2 to 4 were obtained by carrying out the same treatment as in Example 1 except that the following compositions (B) to (D) were used instead of the above composition (A). Ta.

Table 1 shows the polymerization conversion rate in each polymerization reaction, the presence or absence of other particles in polymer emulsions 2 to 4 observed by electron microscopy, the average particle diameter of the polymer particles, and the miscibility with water-soluble solvents. The miscibility with water-soluble solvents was evaluated as follows, based on the amount of aggregates in 100 parts by weight of the polymer emulsion.

A: Less than 0.001 parts by weight B: 0.001 parts by weight or more and less than 0.01 parts by weight C: 0.
OL 1 part by weight or more and less than 1 part by weight D: 1 part by weight or more and less than 10 parts by weight E: 10 parts by weight or more (gelled state) Seed polymer particles (A) 10.0 Styrene 98.5 Methacrylic 1
121.5 Potassium persulfate 0.5 Sodium dodecylbenzenesulfonate 0.1 part Water 150
Part composition (C) (styrene/butadiene-based composition) polymer particles (A) 10.0 styrene
38,0 butadiene
50,0 methacrylic acid
10.0 itaconic acid
1.0 Acrylic acid 1. Ot
-Dodecyl mercaptan 02 Sodium dodecylbenzenesulfonate 0.4 parts Potassium persulfate water 10 parts Polymer particles (b) 100 parts Styrene
200 parts potassium persulfate
1.5 parts Examples 5 to 8 Water-soluble polymer (v) instead of water-soluble polymer (v)
Emulsion polymerization was carried out in the same manner as in Example 1, except that each of i), (vii), (i) and (u) was used to obtain polymer emulsions 5 to 8.

The polymerization conversion rate in each polymerization reaction, the presence or absence of other particles observed in polymer emulsions 5 to 8 using an electron microscope, the average particle diameter of the polymer particles, and the miscibility with water-soluble solvents are as shown in Table 2.

Example 9 Emulsion polymerization was carried out in the same manner as in Example 1 except that the amount of water-soluble polymer (v) was increased to 60 parts to obtain polymer emulsion 9.

The polymerization conversion rate in this polymerization reaction, the presence or absence of other particles as observed by electron microscopy of the polymer emulsion 9, the average particle diameter of the polymer particles, and the miscibility with water-soluble solvents are as shown in Table 2.

Example 10 Emulsion polymerization was carried out in the same manner as in Example 1 except that the amount of water-soluble polymer (v) was reduced to 10 parts to obtain 10 polymer emulsions.

The polymerization conversion rate in this polymerization reaction, the presence or absence of other particles as observed by electron microscopy of the polymer emulsion]0, the average particle diameter of the polymer particles, and the miscibility with water-soluble solvents are as shown in Table 2.

Example 11 Polymer emulsion 11 was obtained by carrying out emulsion polymerization in the same manner as in Example 1 except that the water-soluble polymer (v) was divided into three equal parts and each part was added intermittently at one hour intervals. .

The polymerization conversion rate in this polymerization reaction, the presence or absence of other particles in polymer emulsion 11 observed by electron microscopy, the average particle diameter of the polymer particles, and the miscibility with water-soluble solvents are as shown in Table 2. Comparative Examples 1 and 2 Instead of water-soluble polymer (V), water-soluble polymer (■
Example 1 except that each of 1) and (1v) was used.
Comparative polymer emulsions 1 and 2 were obtained by emulsion polymerization in the same manner as described above.

Table 3 shows the polymerization conversion rate in each polymerization reaction, the presence or absence of separate particles of Comparative Polymer Emulsions 1 and 2 as observed by electron microscopy, the average particle diameter of the polymer particles, and the miscibility with water-soluble solvents.

Comparative Example 3 Comparative polymer emulsion 3 was obtained by carrying out emulsion polymerization in the same manner as in Example 1 except that no water-soluble polymer was used.

The polymerization conversion rate in each polymerization reaction, the presence or absence of other particles as observed by electron microscopy of Comparative Polymer Emulsion 3, the average particle diameter of the polymer particles, and the miscibility with water-soluble solvents are as shown in Table 3.

Comparative Example 4 Emulsion polymerization was carried out in the same manner as in Example 1 except that the seed polymer particles (A) in composition (A) were removed.
Comparative polymer emulsion 4 was obtained.

The polymerization conversion rate in each polymerization reaction, the presence or absence of other particles as observed by electron microscopy of Comparative Polymer Emulsion 4, the average particle diameter of the polymer particles, and the miscibility with water-soluble solvents are as shown in Table 3.

Comparative Example 5 Comparative polymer emulsion 5 was obtained by emulsion polymerization in the same manner as in Example 1 except that all of the water-soluble polymer (v) was added at once before the start of emulsion polymerization.

The polymerization conversion rate in each polymerization reaction, the presence or absence of other particles as determined by electron microscopy observation of Comparative Polymer Emulsion 5, the average particle diameter of the polymer particles, and the miscibility with water-soluble solvents are as shown in Table 3.

〔Effect of the invention〕

According to the method of the present invention, in the method for producing a polymer emulsion in which a vinyl monomer is emulsion polymerized in the presence of seed polymer particles, a specific water-soluble polymer is added continuously or intermittently as the polymerization reaction of the vinyl monomer progresses. By carrying out emulsion polymerization in a specific manner, it is possible to use a wide range of vinyl monomers, giving greater flexibility in the polymerization reaction, reducing the generation of separate particles, and achieving well-controlled and uniform particle sizes. It is possible to produce a polymer emulsion consisting of polymer particles having excellent miscibility with water-soluble solvents.

Claims (1)

[Scope of Claims] 1) A method for producing a polymer emulsion in which emulsion polymerization is carried out while continuously or intermittently adding a vinyl monomer in the presence of seed polymer particles, the weight average molecular weight being 500 to 50 as the polymerization reaction progresses.
,000 of a water-soluble polymer is added continuously or intermittently.