JPS6056161B2 - Method for producing aqueous polymer emulsion - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing a polymer emulsion, and more particularly to a method for producing an aqueous polymer emulsion using a high molecular weight modified vinyl polymer as an emulsifier.

Aqueous synthetic resin emulsions are now widely used in paints, adhesives, paper and fiber treatments, etc., but this means that when synthetic resin aqueous emulsions are used, for example, in paints and adhesives, they become so-called solvent-based emulsions. In comparison, environmental conservation and working environment,
This is preferable from the point of view of saving resources, etc., and also because it has a relatively low viscosity even at high concentrations and has excellent workability.

However, conventional synthetic resin aqueous emulsions are produced in the presence of low molecular weight emulsifiers such as alkyl sulfonates, alkyl sulfates, alkyl carboxylates, etc.
When a film is formed using such an emulsion,
Since the above-mentioned emulsifier remains in the film, there is a problem that the film has poor water resistance, heat resistance, weather resistance, etc. In addition, especially when producing an emulsion of acrylic resin, there are many aggregates and the mechanical stability is poor. There were also problems that were worse. In order to solve such problems, several methods for producing aqueous polymer emulsions using high-molecular-weight emulsifiers have already been proposed, but the present invention belongs to this technical field. By using a vinyl polymer as an emulsifier, no aggregates are generated during emulsion polymerization, and the resulting emulsion has excellent mechanical stability, and the film formed by the emulsion has excellent water resistance, heat resistance, and weather resistance. The object of the present invention is to provide a method for producing an aqueous polymer emulsion that is excellent in various physical properties such as properties.

The method for producing an aqueous polymer emulsion of the present invention can be carried out using the general formula (wherein R represents hydrogen or a methyl group, X represents 101 or -NH-, and M represents hydrogen or a base cation.

) in the side chain, and has an acid value of about 30 to 3.
This method is characterized in that a radically polymerizable monomer is subjected to aqueous emulsion polymerization using a modified vinyl polymer No. 50 as an emulsifier. The modified vinyl polymer as described above is a polymer having at least one group among a hydroxyl group, an epoxy group, and an amino group in a side chain (hereinafter referred to as a functional vinyl polymer).

) to cis-Δ4-tetrahydrophthalic anhydride or cis-3
- A tetrahydrophthalic anhydride compound such as methyl-Δ4-tetrahydrophthalic anhydride is reacted in the same manner as a normal esterification reaction or amidation reaction to esterify and/or esterify the functional group of the functional vinyl polymer. A vinyl monomer that can be obtained by amidation and has both a polymerizable unsaturated group and at least one group among a hydroxyl group, an epoxy group, and an amino group in the molecule is prepared in advance by the above method. A modified vinyl monomer is obtained by esterification and/or amidation with a tetrahydrophthalic anhydride compound, and this monomer is polymerized, if desired, with other appropriate vinyl monomers according to a conventional method. It can also be obtained by More specifically, the modified vinyl polymer includes hydroxyethyl (meth)acrylate and hydroxypro. Hydroxyalkyl (meth)acrylates such as vinyl (meth)acrylate, polyalkylene glycol (meth)acrylates such as diethylene glycol mono(meth)acrylate and polypropylene glycol mono(meth)acrylate, N-
Mechi! Role (meth)acrylamide, allyl alcohol, glycidyl (meth)acrylate, aminoethyl (
It is a polymer having as a structural unit a compound such as meth)acrylate or diallylamine in which a group represented by the above general formula is bonded to at least one hydroxyl group, epoxy group and/or amino group.

Usually, (meth)acrylic acid alkyl esters such as butyl (meth)acrylate and 2-ethylhexyl (meth)acrylate, alkenylbenzenes such as styrene, a-methylstyrene, and vinyltoluene, and vinyls such as vinyl acetate and acrylonitrile are usually used. A copolymer with a monomer is used, preferably a hydroxyalkyl (meth)acrylate in which the tetrahydrophthalic anhydride compound is bonded to its hydroxyl group via an ester bond, and an alkyl (meth)acrylate ester. and/or a copolymer having alkenylbenzene as a structural unit. Polyvinyl j-butyral or polyvinyl alcohol whose hydroxyl group is esterified with a tetrahydrophthalic anhydride compound can also be used as the modified vinyl polymer. Note that the modified vinyl polymer may have a hydrophilic structural unit such as (meth)acrylic acid or (meth)acrylamide, if necessary. Esterification and/or amidation of the functional vinyl monomer with a tetrahydrophthalic anhydride compound can be carried out by a conventional method. For example, in the esterification reaction, the two are mixed, and if necessary, a solvent is used, a common esterification catalyst such as benzoic acid or triethylamine, and a polymerization inhibitor such as hydroquinone.
It progresses easily by heating. The radical copolymerization reaction between the modified vinyl monomer thus obtained and a vinyl monomer such as an alkyl (meth)acrylate or alkenylbenzene can be carried out by any conventionally known method. Esterification and amidation of the functional vinyl polymer with a tetrahydrophthalic anhydride compound are also the same as above. In the present invention, the modified vinyl polymer is adjusted to have an acid value of about 30-350.

When the acid value is less than about 30, when emulsion polymerizing a radically polymerizable monomer using this as an emulsifier, the emulsifying ability is small and a good polymer emulsion cannot be obtained, such as the formation of aggregates, and When the acid value is higher than about 350, it is also not preferred because the emulsifying ability is low and the film formed by the resulting emulsion is poor in water resistance. A particularly preferred range of acid values is about 50-200. As mentioned above, tetrahydrophthalic anhydride compounds impart excellent emulsifying ability to polymers and, at the same time, contain air through the double bonds of their tetrahydrophthalic acid rings in polymer emulsions obtained by using them as emulsifiers. Provides hardenability.

Therefore, in order for the modified vinyl polymer to have an acid value within the above range and sufficient air curability, the tetrahydrophthalic anhydride compound should account for about 5 to 5 weight percent of the modified vinyl polymer. It is better to do so. Furthermore, the modified vinyl polymer has a weight average molecular weight of 500 to 10,000.
Preferably, it is in the range of 0. If the molecular weight is too small, the emulsifying ability will be low and it will be difficult to obtain a good emulsion; if the molecular weight is too large, the viscosity will be too high when dissolved in water, and only a small amount can be used, which will still produce a good emulsion. This is because it is difficult to obtain a suitable emulsion. A particularly preferable weight average molecular weight range is 1,000 to 80,000. The modified vinyl polymer is neutralized with a base to form an aqueous solution,
Used as an emulsifier for emulsion polymerization. The above base is not particularly limited, and various bases can be used,
For example, alkali metal hydroxides such as sodium hydroxide, alkali metal oxides, carbonates, bicarbonates, ammonia, and amines can be used. Specific examples of amines include triethylamine, diethanolamine, and tetramine. Therefore, specific examples of the base cation in the above general formula include alkali metal ions such as sodium ions, ammonium ions, amine cations, and the like. The aqueous solution of the modified vinyl polymer neutralized in this way may contain a water-soluble organic solvent, and examples of these water-soluble organic solvents include ethylene glycol, propylene glycol, ethyl cellosolve, butyl cellosolve, and butyl cellosolve. Examples include glycols such as carbitol and butyl cellosolve acetate, and their alkyl ethers and alkyl ether esters. In the presence of modified vinyl polymer,
When emulsion polymerizing a radically polymerizable monomer, the amount of the modified vinyl polymer used is usually about 5 to 100 parts per 100 parts of the monomer (all parts are by weight).
It is. If it is less than about 5 parts, the emulsion stability during emulsion polymerization will be insufficient, and if it is more than about 10 parts, the resulting coating will have insufficient water resistance and chemical resistance. In addition,
In order to further improve the drying properties, water resistance, oil resistance, etc. of the film from the resulting emulsion, an appropriate amount of a desiccant commonly used in paints, such as cobalt naphthenate, manganese naphthenate, lead naphthenate, etc. It may be added during emulsion polymerization or after polymerization. In the present invention, the radically polymerizable monomer that can be emulsion polymerized using the modified vinyl polymer as an emulsifier is not particularly limited, and includes all monomers that have conventionally been subjected to emulsion polymerization. Specific examples include (meth)acrylic acid alkyl esters and glycidyl (meth)acrylate such as methyl (meth)acrylate, ethyl (meth)acrylate, butyl (meth)acrylate, and 2-ethylhexyl (meth)acrylate, as well as styrene, α- Alkenylbenzenes such as methylstyrene and vinyltoluene, as well as vinyl acetate, vinylpyridine, butadiene, isoprene, chloroprene,
Examples include acrylonitrile and methacrylonitrile. These monomers may be used alone or as a mixture of two or more, but if necessary, a small amount of acrylic acid, methacrylic acid, itaconic acid, maleic anhydride, acrylamide, methacrylamide, dimethylaminoethyl methacrylate may be added to these monomers. , N-methylolacrylamide, N-butoxymethylacrylamide, 2-hydroxypropyl acrylate, 2-hydroxyethyl methacrylate, 2
- Hydrophilic monomers such as acrylamide 2-methylpropanesulfonic acid and styrene sulfonic acid may be used in combination, and small amounts of ethylene glycol dimethacrylate, tetraethylene glycol diacrylate, butylene glycol dimethacrylate, neopentyl glycol dimethacrylate, etc. A polyfunctional crosslinking agent such as glycol diacrylate such as methacrylate, dimethacrylate, diallyl phthalate, etc. may be used in combination. In order to carry out emulsion polymerization in the present invention, conventionally known methods can be employed.

7. For example, in the presence of the above-mentioned modified vinyl polymer, the above-mentioned monomers may be reacted with a radical polymerization initiator in water or in an aqueous solution containing the above-mentioned water-soluble organic solvent, and if necessary, the above-mentioned hydrophilic monomers. Emulsion polymerization is carried out at a temperature of 0 to 100°C using a polyfunctional crosslinking agent, a drying agent, etc.

The radical polymerization initiator may be water-soluble or oil-soluble, and includes, for example, peroxides such as benzoyl peroxide, cumene hydroperoxide, and hydrogen peroxide, azo compounds such as azobisisobutyronitrile, ammonium persulfate, and potassium persulfate. Redox catalysts such as persulfates, perchloric acid compounds, and combinations of persulfate compounds and reducing sulfoxy compounds can be used. Polymerization can also be initiated by irradiation with gamma rays or electron beams. As described above, since the method of the present invention uses a modified vinyl polymer with high emulsifying ability, no aggregates are generated during emulsion polymerization, and the resulting emulsion also has good mechanical stability, storage stability, pigment miscibility, etc. Excellent.

Furthermore, since the emulsifier itself has air curability, the film formed by the emulsion has excellent properties in many respects such as water resistance, heat resistance, and weather resistance. Furthermore, the resulting emulsion generally has excellent compatibility with water-soluble resins, and can easily be used in combination with epoxy resins, phenol resins, urea resins, melamine resins, etc., depending on the purpose of use. Examples are shown below. Example 1 In a 1' container, 285y of cis-3-methyl-Δ4-tetrahydrophthalic anhydride, 200y of 12-hydroxyethy5-acrylate, and 0.5y of triethylamine as an esterification catalyst were charged, and the monomer content of the modified acrylate was left at room temperature for 3 hours. I got a body.

In a 1' separable flask equipped with a stirrer, a thermometer, a dropping funnel, a condenser tube and a nitrogen inlet tube, add 1 portion of butylnicerosolve.
After charging 50 g, purging the inside of the flask with nitrogen and raising the temperature to 120°C, the above modified monomer 75.5y in which azobisisobutyronitrile 59 was dissolved, butyl methacrylate 93.4f, and butyl acrylate 31 were added. A mixed solution consisting of .1f was added dropwise over 2 hours and stirred for an additional 3 hours to carry out a copolymerization reaction to obtain a colorless and transparent butyl cellosoluble solution of a modified polymer having an acid value of 91 and a weight average molecular weight of 8,000. Next, 35y1 of the modified polymer solution, 120f of pure water, and 5 da of 28% ammonia water were charged into a separable flask similar to the above, and stirred under a nitrogen atmosphere to neutralize and dissolve the modified polymer. This modified polymer water solution contains 80 da of butyl methacrylate and 0.1 f of potassium persulfate.
and 10 y of ion-exchanged water were added and thoroughly stirred to emulsify butyl methacrylate. Next, the mixture was heated to a temperature of 7° C. in a nitrogen atmosphere and subjected to emulsion polymerization for 6 hours to obtain an emulsion. The polymerization reaction proceeded uniformly and no aggregates were generated. The physical properties of the obtained emulsion are shown in the table.
Examples 2 to 3 Emulsions were prepared in the same manner as in Example 1, except that the emulsifier obtained in Example 1 was used to emulsion polymerize the monomers shown in the table.

The physical properties of the obtained emulsion are shown in the table. Examples 4-6 Diethylene glycol monomethacrylate 50f1 butyl methacrylate 250y and butyl acrylate 80f were prepared in butyl cellosol acetate 435' using azobisisobutyronitrile 20y. To this, 100v of cis-Δ4-tetrahydrophthalic anhydride and 1.0g of triethylamine were added.
was added and reacted at a temperature of 80°C for 11 hours to reach an acid value of 1.
10. A modified vinyl polymer solution having a weight average molecular weight of 6,200 was obtained.

This modified polymer solution 35f was prepared in the same manner as in Example 1,
The mixture was neutralized and used as an emulsifier, and the monomers shown in the table were emulsion copolymerized. The physical properties of the obtained emulsion are shown in the table. Comparative Example In the same manner as in Example 1, butyl methacrylate 80y was emulsion polymerized in a mixed solution of butyl cellosolve 159 and pure water 130f using 0.3y sodium laurate and 0.7y polyoxyphenyl ether as emulsifiers.

Generation of aggregates was observed, and water resistance was not good. The various physical properties in the table were evaluated as follows.

(1) Acid value: Dissolve the sample in toluene/ethanol (9/1), use phenolphthalein as a test agent, and add 0.1
Neutralization titration was performed with N potassium hydroxide ethanol solution.

(2) Coagulation rate: The emulsion was filtered through an 80-mesh wire mesh, the filter residue was dried, and the weight percentage relative to the solid content of the original emulsion was determined.

(3) Average particle size: Determined by turbidity method using Sakurada method.

(4) Weight average molecular weight: Sample solution in tetrahydrofuran (4). 5%), Waters GPC-2
It was determined by gel permeation chromatography using a drum machine. (5) Water resistance: The emulsion was casted on a Teflon plate and left to dry at room temperature for 10 days to produce a film with a thickness of 150 μm.

Claims (1)

[Claims] 1. General formula ▲ Numerical formula, chemical formula, table, etc. ▼ (In the formula, R represents hydrogen or a methyl group, X represents -O- or -NH-, and M represents hydrogen or a base positive ion) in the side chain, and has an acid value of about 30 to 3.
A method for producing an aqueous polymer emulsion, which comprises carrying out aqueous emulsion polymerization of a radically polymerizable monomer using a modified vinyl polymer of No. 50 as an emulsifier. 2. The method for producing an aqueous polymer emulsion according to claim 1, wherein the modified vinyl polymer has a weight average molecular weight of 500 to 100,000.