JPH09132648A - Polymeric dispersant, its production and method for performing emulsion polymerization by using it - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a polymeric dispersant which can be used in the polymerization of 2-ethylhexyl acrylate difficultly polymerizable by the use of a conventional polymeric dispersant. SOLUTION: This polymeric dispersant comprises a polymer comprising 3-30wt.% repeating units derived from an ethylenically unsaturated carboxylic acid, a solvent of an SP value of 10-14 and water. This dispersant is prepared by polymerizing a monomer mixture containing 3-30wt.% ethylenically unsaturated carboxylic acid in a solvent and distilling the solvent out of the reaction mixture so that the content of the solvent after the addition of water may amount to 0.5-60wt.% of the formed polymer constituting the polymeric dispersant. It is prepared also by polymerizing a monomer mixture containing 3-30wt.% ethylenically unsaturated carboxylic acid in a solvent, substantially perfectly distilling the solvent out of the reaction mixture, adding water to the mixture and adding a solvent so that it may amount to 0.5-60wt.% of the formed polymer constituting the polymeric dispersant.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a polymer dispersant capable of providing stable emulsion polymerization, a method for producing the same, and an emulsion polymerization method using the same, and more particularly to agglomeration and coalescence during polymerization. A polymer dispersant which can be stably polymerized without causing problems such as 2-ethylhexyl acrylate, which has been difficult to polymerize with a conventional polymer dispersant, and a method for producing the same. And an emulsion polymerization method using the same.

[0002]

2. Description of the Related Art
As a method for synthesizing a synthetic resin emulsion, emulsion polymerization using an emulsifier is generally used. However, this emulsifier, which is indispensable for ensuring the polymerization stability and the dispersion stability of the synthetic resin emulsion produced, has the drawback that it adversely affects various properties such as the water resistance of the film after drying and the adhesion to the substrate. ing. One way to improve these shortcomings is:
Emulsion polymerization using a polymer dispersant, that is, a protective colloid polymerization method can be mentioned. However, in the case of this polymerization method, the monomer that can be emulsion-polymerized is often limited depending on the composition of the polymer dispersant used, and particularly, a monomer mixture containing 2-ethylhexyl acrylate alone or in a large amount can be stably used. It was very difficult to polymerize.

[0003]

As a result of various studies to solve the above-mentioned problems, the present inventors have found that the object of the present invention can be achieved by adopting the following constitution, and arrived at the present invention. It was. That is, the polymer dispersant of the present invention,
A polymer dispersant containing a polymer containing 3 to 30% by weight of an ethylenically unsaturated carboxylic acid unit, a solvent, and water, wherein the SP value of the solvent is 10 to 14 and the content thereof is It is 0.5 to 60% by weight of the polymer.

The present invention is also a method for producing the polymer dispersant of the present invention, in which a monomer mixture containing 3 to 30% by weight of an ethylenically unsaturated carboxylic acid is polymerized in a solvent. After that, the solvent has a SP value of 10 to 1 in the method for producing a polymer dispersant by distilling off the solvent and adding water.
4, and the solvent is distilled off so that the content of the solvent after the addition of water is 0.5 to 60% by weight of the polymer constituting the polymer dispersant obtained by the polymerization. And a method for producing a polymer dispersant.

Furthermore, the present invention is another method for producing the polymer dispersant of the present invention, in which a monomer mixture containing 3 to 30% by weight of an ethylenically unsaturated carboxylic acid is polymerized in a solvent. Then, in a method for producing a polymer dispersant, which comprises distilling off the solvent and adding water, after distilling off the solvent almost completely and adding water, a solvent having an SP value of 10 to 14 is added, 0.5 of the polymer constituting the polymer dispersant obtained by the polymerization
It is a method for producing a polymer dispersant, which is characterized in that it is added in an amount of ˜60% by weight.

Furthermore, in a method of emulsion-polymerizing 2-ethylhexyl acrylate or a monomer mixture containing 55% by weight or more of all monomers, 3 to 3 ethylenically unsaturated carboxylic acid units are used as the dispersant. 30% by weight
A polymer dispersant comprising a polymer, a solvent having an SP value of 10 to 14, and water, wherein the content of the solvent is 0.5 to 60% by weight of the polymer. It is a characteristic emulsion polymerization method.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION The polymer dispersant of the present invention is a polymer dispersant containing a polymer containing 3 to 30% by weight of an ethylenically unsaturated carboxylic acid unit, a solvent, and water,
The SP value of the solvent is 10 to 14, and the content thereof is 0.5 to 60% by weight of the polymer.

The polymer constituting the polymer dispersant of the present invention contains 3 to 30% by weight of an ethylenically unsaturated carboxylic acid unit.
Examples of the ethylenically unsaturated carboxylic acid which is a contained polymer include acrylic acid, methacrylic acid and itaconic acid. This ethylenically unsaturated carboxylic acid is contained in an amount of 3 to 30 of the copolymer constituting the polymer dispersant in the present invention.
It is used so as to account for wt%, preferably 5 to 20 wt%. If it is 3% by weight or less, it is not sufficiently solubilized in water even when an alkali is added, and conversely, if it is 30% by weight or more, it is presumed that the dispersion particle stabilizing effect of the dispersant is reduced, but it is stable. Realization of emulsion polymerization is difficult.

The monomer to be copolymerized with the ethylenically unsaturated carboxylic acid used in the present invention is not particularly limited, but an alkyl ester of acrylic acid or methacrylic acid having 1 to 8 carbon atoms (for example, acrylic acid or Methyl, ethyl, isopropyl, n-propyl, n-butyl, isobutyl, t-butyl esters of methacrylic acid), vinyl aromatic compounds (eg styrene), vinyl halides (eg vinyl chloride, vinylidene chloride), Examples thereof include saturated carboxylic acid vinyl ester (for example, vinyl acetate, vinyl propionate), acrylonitrile, methacrylonitrile, and the like.

The glass transition temperature of this polymer dispersant is not particularly limited, but it is 0 to 100 ° C. from the viewpoint of polymerization stability.
It is preferred that The solvent constituting the polymer dispersant of the present invention has an SP value of 10 to 14, preferably 11 to 1.
3, most preferably 11-12 organic solvents. SP
When the value is 10 or less, when the present polymer dispersant is used for emulsion polymerization, the resulting resin is swelled and softened by dissolution, which destabilizes the polymerization, which is not preferable. In the above, the dispersing action of the polymer dispersant is lowered, and the polymerization is destabilized.

Examples of the solvent used in the present invention include ethyl alcohol (12.7), n-propyl alcohol (11.9) and isopropyl alcohol (11.
5), n-butyl alcohol (11.4), isobutyl alcohol (10.5), s-butyl alcohol (1
0.8), t-butyl alcohol (10.6), methyl cellosolve (11.4), ethyl cellosolve (10.
5), diethylene glycol (12.1), dimethylformamide (12.1) and the like, and preferably isopropyl alcohol (the value in parentheses is the SP value of the solvent). The SP value when two or more solvents are used in combination is SP _mixture = Σ _i (X _i · SP _i ).
(Note that X _i : mole fraction of the i component, SP _i : SP of the i component
The value is the mole fraction. ).

The content of this solvent in the polymer dispersant of the present invention is 0.5 to 60% by weight, preferably 3 to 50% by weight, and most preferably 1% by weight of the polymer constituting the polymer dispersant.
It should be 0 to 30% by weight. When it is 0.5% by weight or less, when the polymer dispersant of the present invention is used for emulsion polymerization, almost no contribution to stabilization of polymerization is seen, and when it is 60% by weight or more, swelling of the resin produced, The softening effect of the dissolution makes the polymerization unstable.

The concentration of the polymer in the polymer dispersant of the present invention is not particularly limited, but is 0.1 from the viewpoint of operability.
Preferably, it is about 50% by weight. As one of the methods for producing the polymer dispersant of the present invention, a monomer mixture containing 3 to 30% by weight of an ethylenically unsaturated carboxylic acid is polymerized in a solvent according to a conventional method, and then the solvent is removed. The content is 0.5 to 60% by weight of the polymer constituting the polymer dispersant obtained by the polymerization, for example, after distilling off under reduced pressure, water is added, and if necessary, an alkali is further added. Is added to obtain a polymer dispersant. The SP value of the solvent used at this time must be 10-14.

As another method for producing the polymer dispersant of the present invention, a monomer mixture containing 3 to 30% by weight of an ethylenically unsaturated carboxylic acid is polymerized in a solvent according to a conventional method. For example, after the solvent is almost completely distilled off under reduced pressure, water is added, and then an alkali is further added if necessary, and then a polymer dispersant obtained by polymerizing a solvent having an SP value of 10 to 14 is added. 0.5 to 60 of the constituent polymer
A polymer dispersant is added so that the weight% of the polymer is added. With this method, since the SP value is other than 10 to 14, it is inconvenient to be contained in the final dispersant,
It makes it possible to use advantageous solvents for preparing the polymeric dispersants.

Further, as another method for producing the polymer constituting the polymer dispersant, according to a conventional emulsion polymerization, that is, the monomer mixture constituting the polymer is emulsion polymerized by using an emulsifier, 0.5 to 6 of the polymer constituting the polymer dispersant obtained by polymerizing a solvent having an SP value of 10 to 14 by adding alkali to water-solubilize it in advance.
There is also a method of adding 0 wt% so that in this method it is essential to use a chain transfer agent for controlling the molecular weight.

In the present production method, the ethylenically unsaturated carboxylic acid used, the unsaturated monomer copolymerizable therewith, and the solvent are the same as those described for the polymer dispersant of the present invention. Is. The polymerization initiator used is preferably an inorganic peroxide such as potassium persulfate, sodium persulfate, ammonium persulfate, hydrogen peroxide, but other azo-based initiators such as azobisisobutyronitrile and azobisvaleronitrile. Agents: Organic peroxide initiators such as benzoyl peroxide, lauroyl peroxide and t-butyl peroxide can also be used. Further, a reducing agent such as Rongalit, L-ascobic acid, an organic amine, and a metal salt may be used in combination with these initiators and used as a redox initiator.

Further, it is possible to use a chain transfer agent such as an organic halide or an alkyl mercaptan as a molecular weight regulator when polymerizing each constituent monomer mixture according to a conventional method. The alkali used herein may be ammonia, an organic amine such as triethylamine or ethanolamine, or an inorganic alkali such as sodium hydroxide, but it is most preferable to use ammonia.

The thus-obtained polymer dispersant of the present invention can be used for emulsion polymerization of a desired monomer, and the emulsion polymerization method using it can be carried out according to a conventional method.
Of course, a polymerization initiator is used in that case. That is, as a dispersant, a polymer containing 3 to 30% by weight of an ethylenically unsaturated carboxylic acid unit, a solvent having an SP value of 10 to 14, and water are contained, and the content of the solvent is 0.5 of the polymer. ~ 60% by weight
Emulsion polymerization will be carried out using the above polymeric dispersant.

As the monomer for this emulsion polymerization, various kinds can be used depending on the intended use of the synthetic resin emulsion to be produced. Typical examples include unsaturated carboxylic acids (eg acrylic acid and methacrylic acid), unsaturated carboxylic acid amides (eg acrylic acid amide and methacrylic acid amide), and alkyl or methacrylic acid alkyl having 1 to 8 carbon atoms. Esters (eg, methyl or ethyl of acrylic acid or methacrylic acid, isopropyl, n-
Propyl, n-butyl, isobutyl, t-butyl etc.), vinyl aromatic compounds (eg styrene), vinyl halides (eg vinyl chloride, vinylidene chloride), saturated carboxylic acid vinyl esters (eg,
Vinyl acetate, vinyl propionate), acrylonitrile, methacrylonitrile, etc., but it has been difficult to polymerize using a conventional polymer dispersant.
Ethylhexyl acrylate or 55% of total monomer
It is possible to stably polymerize a monomer mixture containing at least wt%.

The amount of the polymer dispersant of the present invention used in emulsion polymerization is not particularly limited, but preferably, the amount of the polymer constituting the polymer dispersant is 100% by weight as a polymer constituting the polymer dispersant. 1 to 200 parts by weight, especially 2 for a monomer mixture containing a large amount of 2-ethylhexyl acrylate.
0 to 100 parts by weight is more preferable. Further, to the extent that the excellent properties of the polymer dispersant of the present invention are not impaired, it is also possible to use an emulsifier and other dispersants in combination, and the emulsifiers used in combination include sodium dialkylsulfosuccinate and alkyl sulfonic acid. Examples include various kinds of anionic surfactants such as alkali metal salts, alkyl metal salts of oxyalkylated alcohols or alkylphenols, alkali metal salts of fatty acids, and nonionic surfactants.

In the emulsion polymerization method of the present invention, the dispersibility of the polymer dispersant used tends to deteriorate in the acidic region, so that special consideration is required in such a case. That is, when the emulsion polymerization of the present invention is carried out using an unsaturated carboxylic acid such as acrylic acid or methacrylic acid, or when a persulfate is used as an initiator, the polymerization reaction system has an acidic region. In such a case, it is desirable to add an alkali to the polymerization reaction system to stabilize it.

[0022]

EXAMPLES The present invention will now be described in detail with reference to production examples of polymer dispersants and examples. Parts and% in the examples are parts by weight and% by weight unless otherwise specified. Polymer Dispersant Production Example 1 Isopropyl alcohol 150 was added to a reactor equipped with a temperature controller, a stirrer, a reflux condenser, a supply container and a nitrogen inlet tube.
A part was charged and the atmosphere was replaced with nitrogen. After heating the reactor to 80 ° C., a mixture of 100 parts of the monomer solution described in Table 1 and 0.1 part of t-dodecyl mercaptan was supplied from a supply container, and 2 parts of azobisisobutyronitrile was added to isopropyl alcohol.
What was melt | dissolved in 0 part was uniformly added from another supply container over 4 hours.

After the completion of the addition, the reactor was kept at 80 ° C. and aged for 2 hours to obtain a uniform polymer solution. Then, excess isopropyl alcohol was distilled off under reduced pressure using a rotary evaporator, and then deionized water was added to further neutralize ammonia to obtain a resin-containing aqueous solution having a pH of 8 and a resin solid content of 25%. The polymer had a weight average molecular weight of about 10,000 as measured by gel permeation chromatography (GPC).
Further, when the amount of isopropyl alcohol in this resin aqueous solution was measured by gas chromatography,
It was 4.5%.

[0024]

[Table 1]

Polymer Dispersant Preparation Examples 2 to 3 Using the same equipment as in Polymer Dispersant Preparation Example 1, the monomer composition, solvent, initiator, etc. were changed as shown in Table 1 to obtain uniform polymers. After obtaining the solution, the solvent was distilled off, water substitution and neutralization were performed to obtain resin-containing aqueous solutions as shown in Table 1, respectively.

Polymer Dispersant Preparation Example 4 Using the same equipment as in Polymer Dispersant Preparation Example 1, the monomer composition, solvent, initiator, etc. were changed as shown in Table 1 to obtain a uniform polymer solution. Then, the solvent was distilled off almost completely, and then deionized water and ammonia were added to neutralize the solvent.
-By adding butanol, a resin-containing aqueous solution as shown in Table 1 was obtained.

Polymer Dispersant Production Examples 5 to 7 Using the same equipment as in Polymer Dispersant Production Example 1, the monomer composition, solvent, initiator, etc. were changed as shown in Table 1, and each uniform weight was obtained. After the combined solution was obtained, the solvent was distilled off, water substitution and neutralization were carried out to obtain resin-containing aqueous solutions as shown in Table 1, respectively.

Polymer Dispersant Preparation Example 8 Using the same equipment as in Polymer Dispersant Preparation Example 1, the monomer composition, solvent, initiator, etc. were changed as shown in Table 1 to obtain a uniform polymer solution. After the solvent was distilled off almost completely, deionized water and ammonia were added for neutralization, and ethylene glycol was further added to obtain a resin-containing aqueous solution as shown in Table 1.

Polymer Dispersant Production Examples 9 to 10 Using the same equipment as in Polymer Dispersant Production Example 1, the monomer composition, solvent, initiator, etc. were changed as shown in Table 1 to obtain a uniform polymer. After obtaining the solution, the solvent was distilled off, water substitution and neutralization were performed to obtain resin-containing aqueous solutions as shown in Table 1, respectively.

Example 1 Using the same apparatus as in Polymer Dispersant Production Example 1, 50 parts of water and the polymer dispersant-containing aqueous solution (concentration 25%) produced in Polymer Dispersant Production Example 1 were placed in a reactor. 120 parts were inserted.
Separately, the following was prepared as the feed I.

Feed I 2-Ethylhexyl Acrylate 85 parts Methyl Methacrylate 15 parts Feed II Water 40 parts Sodium Persulfate 0.5 parts Sodium Hydroxide 0.12 parts

After the inside of the reactor charged with the above-mentioned initiator solution was replaced with nitrogen gas, 10% of the above-mentioned feed I was added into the reactor and the mixture was heated to 90 ° C. Then, 10% of the feed II was charged into the reactor, and the rest of the feed I and the feed II were uniformly fed to the reactor over 3 to 3.5 hours. After completion of the supply, the mixture was kept at 90 ° C. for 1.5 hours for emulsion polymerization to obtain a copolymer aqueous emulsion. The resin concentration of this copolymer aqueous emulsion was about 40%. The composition of the monomer and the resin concentration of the produced emulsion are summarized in Table 2. When the polymerization stability of the copolymer aqueous emulsion thus obtained was evaluated, it was very excellent.

Polymerization Stability: The above copolymer aqueous emulsion was filtered through a wire mesh of 150 mesh and evaluated according to the following criteria. A: Aggregates less than 0.1% O: Aggregates of 0.1 to 1% B: Aggregates of 1 to 5% X ... Aggregates of more than 5%

[0034]

[Table 2]

Examples 2 to 5 Comparative Examples 1 to 6 The same apparatus as in Example 1 was used, except that the polymer dispersant, the monomer composition, and the initiator were changed as shown in Table 2. An aqueous copolymer emulsion was obtained according to Example 1. The results are summarized in Table 2.

[0036]

According to the polymer dispersant of the present invention, stable emulsion polymerization can be carried out without causing problems such as aggregation and coalescence during polymerization. It is possible to stably emulsion-polymerize various monomers including 2-ethylhexyl acrylate, which was difficult to polymerize.

Claims (4)

[Claims] 1. An ethylenically unsaturated carboxylic acid unit of 3 to
A polymer dispersant containing 30% by weight of a polymer, a solvent, and water, wherein the SP value of the solvent is 10 to 14, and the content thereof is 0.5 to 60% by weight of the polymer. % Is a polymer dispersant. 2. An ethylenically unsaturated carboxylic acid is used in an amount of 3 to 30.
In a method for producing a polymer dispersant, which comprises polymerizing a monomer mixture containing 1% by weight in a solvent, distilling off the solvent and adding water, the SP value of the solvent is 10 to 14. ,
Further, the solvent is distilled off so that the content of the solvent after the addition of water is 0.5 to 60% by weight of the polymer constituting the polymer dispersant obtained by the polymerization. Method for producing polymer dispersant. 3. An ethylenically unsaturated carboxylic acid is used in an amount of 3 to 30.
In a method for producing a polymer dispersant, which comprises polymerizing a monomer mixture containing therein by weight% in a solvent, distilling the solvent off and adding water, the solvent is distilled off almost completely and water is added. And a solvent having an SP value of 10 to 14 are added so as to be 0.5 to 60% by weight of the polymer constituting the polymer dispersant obtained by the polymerization. Dispersant manufacturing method. 4. A method of emulsion-polymerizing 2-ethylhexyl acrylate or a monomer mixture containing 55% by weight or more of all monomers, wherein 3 to 30 ethylenically unsaturated carboxylic acid units are used as the dispersant. A polymer dispersant is used, which comprises a polymer contained by weight%, a solvent having an SP value of 10 to 14, and water, and the content of the solvent is 0.5 to 60% by weight of the polymer. An emulsion polymerization method characterized by the above.