JP2000080108A - Preparation of particulate vinyl polymer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To keep the content of fine emulsion particles, i.e., an impurity, as low as possible and improve the solubility of the resulting polymer in an org. solvent by adding a surfactant after the max. heat of polymn. is reached in suspension polymn. SOLUTION: In a process for preparing a particulate vinyl polymer, a surfactant is added after the max. heat of polymn. is reached in suspension polymn., pref. within 1 hr after the max. heat of polymn. is reached. Pref., the polymer contains carboxylated vinyl monomer units and has an acid value of 5-350 mgKOH/g. The addition of the surfactant at a polymn. temp. of 50-100 deg.C is pref. in terms of the dispersion stability of fine emulsion particles, and a pref. surfactant is an anionic surfactant, esp. a sodium polyoxyethylene alkyl(phenyl) ether sulfate.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for producing a granular vinyl polymer having a very low impurity content.

[0002]

2. Description of the Related Art In recent years, there has been an increasing demand for special coating materials which use a low-boiling organic solvent such as acetone or ethyl acetate and which mainly comprise a film-forming component containing an acid group-containing vinyl polymer.
Since acetone, ethyl acetate and the like have low boiling points, it is difficult to produce an acid group-containing vinyl polymer in ordinary solution polymerization using these as a solvent. Therefore, at present, usually, a solid acid group-containing vinyl polymer is produced by some method and dissolved in a solvent such as acetone or ethyl acetate. As the solid acid group-containing vinyl polymer, a polymer produced by desolvation after solution polymerization has been generally used until now. In recent years, a method of directly producing a granular acid group-containing vinyl polymer by suspension polymerization has begun to be adopted due to the raw material cost of the solvent used as a solvent or environmental problems.

[0003]

However, when a granular acid-containing granular vinyl polymer is produced by suspension polymerization, emulsion polymerization slightly occurs in water in parallel, and a high acid value and / or high molecular weight There is a problem that emulsified fine particles are easily produced as impurities as by-products. Because it is difficult to completely wash and remove such emulsified fine particles, when an acid group-containing granular vinyl polymer produced by suspension polymerization is dissolved in an organic solvent, an insoluble material is generated, and a colorless and transparent material is generated. Sometimes a solution could not be obtained.

[0004] It is an object of the present invention to provide a method for producing a granular vinyl polymer having an extremely small content of impurities.

[0005]

The present inventors have conducted intensive studies to solve the above problems, and as a result, have found a method for producing a granular vinyl polymer which can solve the above problems.
The present invention has been completed. That is, the method for producing a granular vinyl polymer of the present invention is characterized in that a surfactant is added after the polymerization exotherm during suspension polymerization shows a maximum value.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The constituent components of the granular vinyl polymer obtained in the present invention include, for example, (meth) acrylic acid, 2- (meth) acryloxyethylhexahydrophthalic acid, 2- (meth) acrylic acid. Roxypropylhexahydrophthalic acid, 2- (meth) acryloxyethyltetrahydrophthalic acid, 2- (meth) acryloxypropyltetrahydrophthalic acid, 5-methyl-2- (meth) acryloxyethylhexahydrophthalic acid, 2- (Meth) acryloxyethyl phthalic acid, 2- (meth) acryloxypropyl phthalic acid, 2- (meth) acryloxyethyl oxalic acid, 2- (meth) acryloxypropyl oxalic acid, crotonic acid, fumaric acid, maleic acid And acid group-containing monomers such as carboxyl group-containing vinyl monomers such as itaconic acid and sorbic acid. Door can be. These can be used alone or in combination of two or more. Among them, methacrylic acid is preferable.

In addition to the above-mentioned acid group-containing monomers, for example, methyl (meth) acrylate, ethyl (meth) acrylate, n-butyl (meth) acrylate, i-butyl (meth) acrylate, ( T-butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, n-lauryl (meth) acrylate, n-stearyl (meth) acrylate,
Alkyl (meth) acrylates such as cyclohexyl (meth) acrylate, N-phenylmaleimide, N-
Maleimide derivatives such as cyclohexylmaleimide and N-butylmaleimide, 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate,
3-hydroxypropyl (meth) acrylate, (meth)
Vinyl polymerizable monomers having a hydroxyalkyl group such as 4-hydroxybutyl acrylate, 6-hydroxyhexyl (meth) acrylate, acrolein, diacetone acrylamide, formyl styrol, vinyl alkyl ketone, (meth) acrylamide pivalin aldehyde,
Diacetone (meth) acrylate, acetonyl acrylate, 2-hydroxypropyl acrylate acetyl acetate, acetoacetoxyethyl (meth) acrylate, butanediol-1,4-acrylate-acetyl acetate, aldehyde of acrylamidomethylanisaldehyde Group or carbonyl group-containing vinyl monomer, amide group-containing vinyl monomer such as (meth) acrylamide, crotonamide, N-methylolacrylamide, allyl glycidyl ether, glycidyl (meth)
Examples include epoxy group-containing vinyl monomers such as acrylates, aromatic vinyl monomers such as styrene and α-methylstyrene, nitrile group-containing vinyl monomers such as acrylonitrile, and olefin monomers such as butadiene. These can be appropriately selected and used as needed.

[0008] In the vinyl polymer of the present invention, it is preferred that the unit comprising the above-mentioned acid group-containing monomer is contained in the range of 1 to 50% by mass. This is because when the unit composed of the acid group-containing monomer is 1% by mass or more, it becomes difficult to generate emulsified impurities during suspension polymerization.
This is because suspension polymerization tends to proceed stably when the content is 0% by mass or less. More preferably, 5 to 3
The range is 5% by mass.

The acid value of the vinyl polymer of the present invention is 5 to 3
Preferably, it is in the range of 50 mg KOH / g. This is achieved by setting the acid value to 5 mgKOH / g or more.
This is because emulsified impurities tend not to easily occur during suspension polymerization, and when the acid value is 350 mgKOH / g or less, suspension polymerization tends to proceed stably.
Preferably, it is in the range of 30 to 250 mgKOH / g.

[0010] The dispersant used in the suspension polymerization in the present invention can be appropriately selected and used as necessary. For example, poly (meth) acrylic acid alkali metal salt or (meth) acrylic acid Examples thereof include alkali metal salts of a copolymer of methyl (meth) acrylate, polyvinyl alcohol having a saponification degree of 70 to 100%, and methylcellulose. These can be used alone or in combination of two or more.

[0011] In the suspension polymerization of the present invention, the amount of the dispersant used is preferably in the range of 0.001 to 10% by mass in the aqueous suspension. This means that the amount of dispersant is 0.00
When the content is 1% by mass or more, the dispersibility at the time of polymerization tends to be good, and when the content is 10% by mass or less, the dehydration and drying properties of the granular vinyl polymer tend to be good. It is. More preferably, it is in the range of 0.01 to 1% by mass.

[0012] As a method of suspension polymerization in the present invention, the above-mentioned dispersant is dissolved alone or in combination of two or more kinds in water,
A monomer, an oil-soluble polymerization initiator and, if necessary, a chain transfer agent are added, and while stirring, the monomer is adjusted to 0.05 to 1 mm.
It is preferable to disperse the droplets into droplets of the order and to carry out the polymerization under heating.

Examples of the oil-soluble polymerization initiator used at the time of suspension polymerization include, for example, an azo initiator such as azobisisobutyronitrile and an organic peroxide initiator such as benzoyl peroxide. Examples of the chain transfer agent include mercaptans such as n-dodecyl mercaptan and α-methylstyrene dimer.

[0014] The polymerization temperature is not particularly limited, but is 50 to 100.
It is preferable that the temperature is in the range of ° C. in view of dispersion stability during suspension polymerization and reaction time.

In the present invention, it is necessary to add a surfactant after the polymerization exotherm during suspension polymerization reaches a maximum value. As a result, a granular vinyl polymer having an extremely small content of impurities can be produced.

It is considered that this is because the dispersion stability of the emulsified fine particles produced as a by-product is improved, and it is difficult for this to be taken into the granular vinyl polymer as an impurity.

However, if the surfactant is added before the heat of polymerization of the suspension polymerization reaches the maximum value, an extremely large amount of an emulsion is generated during the suspension polymerization, so that the obtained granular vinyl polymer has It is not preferable because the solubility in the organic solvent tends to decrease.

The surfactant is added at the time of suspension because it is necessary to stabilize the dispersion after the granular vinyl polymer is formed and before the by-produced emulsified fine particles are incorporated into the granular vinyl polymer. It is preferable that the polymerization exotherm of the polymerization be within 1 hour from the time when the polymerization exotherm shows the maximum value.
Addition in a temperature range of 00 ° C. is preferred from the viewpoint of stabilizing the dispersion of emulsified fine particles.

Examples of the surfactant include anionic surfactants such as sodium dodecylbenzenesulfonate, sodium polyoxyethylene alkyl (phenyl) ether sulfate and sodium dialkyl sulfosuccinate; and polyoxyethylene alkyl (phenyl) ether. -Nonionic surfactants such as ter, sodium salts of polyoxyethylene sulfate (meth) acrylate, sodium salts of alkyl allyl sulfosuccinate, and anionic polymerizable polymers such as glycerin allyl nonyl phenyl polyoxy ethylene ammonium sulfate ether Surfactant, polyoxyethylene alkylbenzene (meth) acrylate,
Glycerin allyl nonyl phenyl polyethylene glyco-
Nonionic polymerizable surfactants such as luether; alkali metal salts of poly (meth) acrylate; alkali metal salts of copolymers of (meth) acrylic acid and methyl (meth) acrylate; Polyvinyl Alcohol
And polymer-based surfactants such as methylcellulose. These can be used alone or in combination of two or more. Among them, anionic surfactants, particularly sodium polyoxyethylene alkyl (phenyl) ether sulfate, are preferable.

[0020] The amount of the surfactant to be added is as follows.
It is preferably in the range of 0.1 to 3 parts by mass with respect to 00 parts by mass. This is because the dispersion stability of the emulsified fine particles tends to increase by adding the surfactant in an amount of 0.1 parts by mass or more, and by 3 parts by mass or less,
This is because foaming of the suspension tends to be suppressed. More preferably, it is in the range of 0.2 to 1 part by mass.

The target granular vinyl polymer is obtained by subjecting an aqueous suspension of the polymer obtained by the production method of the present invention to, for example, filtration,
It can be obtained by washing and drying.

[0022]

The present invention will be described below in more detail with reference to examples. The acid value is measured by the following method.

Acid value: about 2 g of a vinyl polymer is weighed, and a solvent 5
0 g (acetone / ethanol = 50/50) was added and dissolved, and titrated with 0.2 N potassium hydroxide (ethanol solution) based on the discoloration point of phenolphthalein to obtain a vinyl polymer. The following formula was used to determine the number of mg of KOH required to neutralize 1 g.

Acid value (mgKOH / g) = A × 0.2 × f × 5
6.1 / sample mass A: titer (ml), f: titer of 0.2N potassium hydroxide solution

[0025]

Example 1 In a polymerization apparatus capable of heating and cooling, 200 parts by mass of deionized water and polyvinyl alcohol (a saponification degree of 8) were added.
0%, polymerization degree 1,700) 0.6 parts by mass and stirred,
After the polyvinyl alcohol was completely dissolved, the stirring was stopped once, and 50 parts by mass of methyl methacrylate and 1 part of styrene were added.
0 parts by mass, 35 parts by mass of n-butyl methacrylate, and 5 parts by mass of methacrylic acid were added and stirred again. 0.3 parts by mass of azobisisobutyronitrile and 1 part by mass of n-dodecylmercaptan were added, and the temperature was raised to 75 ° C. The reaction was carried out for 2 hours while maintaining the reaction temperature of 75 to 80 ° C., and the maximum value of the heat generated by the polymerization was confirmed. After 30 minutes, 1 part by mass of sodium polyoxyethylene alkyl ether sulfate was added and the temperature was raised to 95 ° C. Then, this state was maintained for 1 hour to terminate the reaction. The obtained aqueous suspension was filtered and washed with a nylon filter cloth having a mesh size of 45 µm, and the filtrate was dried at 40 ° C for 16 hours to obtain a granular vinyl polymer having an acid value of 31.3 mgKOH / g. .
The 30% by mass ethyl acetate solution of the obtained vinyl polymer was colorless, transparent and in a good state.

[0026]

Example 2 In a polymerization apparatus capable of heating and cooling, 200 parts by mass of deionized water and polyvinyl alcohol (saponification degree 8
0%, polymerization degree 1,700) 0.6 parts by mass and stirred,
After the polyvinyl alcohol was completely dissolved, stirring was stopped once, and 45 parts by weight of methyl methacrylate, 30 parts by weight of n-butyl methacrylate, 10 parts by weight of styrene, 10 parts by weight of 2-ethylhexyl acrylate, and 5 parts by weight of methacrylic acid
Parts by mass and stirred again, adding 0.3 parts by mass of azobisisobutyronitrile and 0.7 parts by mass of n-dodecylmercaptan, raising the temperature to 75 ° C, and maintaining the reaction temperature of 75 to 80 ° C. After reacting for 2 hours, confirm the maximum value of heat generated by polymerization.
Thirty minutes later, 0.5 parts by mass of sodium polyoxyethylene alkyl ether sulfate was added, and the temperature was raised to 95 ° C., and this state was maintained for one hour to terminate the reaction. The obtained aqueous suspension was filtered through a nylon filter cloth having an opening of 45 μm,
After washing, the filtrate was dried at 40 ° C. for 16 hours and the acid value was 3
A granular vinyl polymer of 1.4 mgKOH / g was obtained. The 30% by mass MEK solution of the obtained vinyl polymer was colorless, transparent and in a good state.

[0027]

Example 3 In a polymerization apparatus capable of heating and cooling, 200 parts by mass of deionized water and polyvinyl alcohol (saponification degree 8
0%, polymerization degree 1,700) 0.6 parts by mass and stirred,
After the polyvinyl alcohol was completely dissolved, the stirring was stopped once, and 20 parts by mass of methyl methacrylate and styrene 3
0 parts by mass, 15 parts by mass of n-butyl acrylate and 35 parts by mass of methacrylic acid were added and stirred again, 3 parts by mass of benzoyl peroxide and 2 parts by mass of α-methylstyrene dimer were added, and the temperature was raised to 85 ° C. The reaction was carried out for 2 hours while maintaining the reaction temperature of 90 ° C., and the maximum value of the heat generated by the polymerization was confirmed. After 30 minutes, 2 parts by mass of sodium polyoxyethylene alkyl ether sulfate was added, and the temperature was raised to 95 ° C. Was maintained for 1 hour to terminate the reaction. The obtained aqueous suspension was filtered through a nylon filter cloth having an opening of 45 μm,
After washing, the filtrate was dried at 40 ° C. for 16 hours and the acid number was 22.
1.3 mg KOH / g of a granular vinyl polymer was obtained. The 30% by mass acetone solution of the obtained vinyl polymer was colorless, transparent and in a good state.

[0028]

Example 4 In a polymerization apparatus capable of heating and cooling, 200 parts by mass of deionized water and polyvinyl alcohol (saponification degree 8
0%, polymerization degree 1,700) 0.6 parts by mass and stirred,
After the polyvinyl alcohol was completely dissolved, the stirring was stopped once, 50 parts by weight of methyl methacrylate, 30 parts by weight of n-butyl methacrylate, and 20 parts by weight of methacrylic acid were added, followed by stirring again, and 1 part by weight of lauroyl peroxide and 0.5 part by mass of α-methylstyrene dimer was added to give 7
The temperature was raised to 5 ° C, and the reaction was carried out for 2 hours while maintaining the reaction temperature of 75 to 80 ° C. The maximum value of the heat generated by the polymerization was confirmed. The temperature was raised, and this state was maintained for 1 hour to terminate the reaction. The resulting aqueous suspension was filtered and washed with a nylon filter cloth having a mesh size of 45 μm, and the filtrate was filtered at 40 ° C. for 1 hour.
After drying for 6 hours, a granular vinyl polymer having an acid value of 127.7 mgKOH / g was obtained. 30 of the obtained vinyl polymer
The mass% acetone solution was colorless, transparent and in a good state.

[0029]

Example 5 In a polymerization apparatus capable of heating and cooling, 200 parts by mass of deionized water and polyvinyl alcohol (a saponification degree of 8) were added.
0%, polymerization degree 1,700) 0.6 parts by mass and stirred,
After the polyvinyl alcohol was completely dissolved, the stirring was stopped once, and 15 parts by mass of methyl methacrylate and styrene 3
0 parts by mass, 20 parts by mass of ethyl acrylate and 35 parts by mass of methacrylic acid are added and stirred again, 3 parts by mass of benzoyl peroxide and 2 parts by mass of α-methylstyrene dimer are added, and the temperature is raised to 85 ° C., and 85 to 90 ° C. The reaction temperature was maintained for 2 hours, and the maximum value of the heat generated by polymerization was confirmed.
After 0 minute, 1 part by mass of polyvinyl alcohol having a degree of saponification of 80% and a degree of polymerization of 1,700 was added, and the temperature was raised to 95 ° C., and this state was maintained for 1 hour to terminate the reaction. The obtained aqueous suspension was filtered through a nylon filter cloth having an opening of 45 μm,
After washing, the filtrate was dried at 40 ° C. for 16 hours and the acid value was 21.
A granular vinyl polymer of 9.0 mgKOH / g was obtained. The 30% by mass acetone solution of the obtained vinyl polymer was colorless, transparent and in a good state.

[0030]

Comparative Example 1 In a polymerization apparatus capable of heating and cooling, 200 parts by mass of deionized water and polyvinyl alcohol (saponification degree 8
0%, polymerization degree 1,700) 0.6 parts by mass and stirred,
After the polyvinyl alcohol was completely dissolved, the stirring was stopped once, and 50 parts by mass of methyl methacrylate and 1 part of styrene were added.
0 parts by mass, 35 parts by mass of n-butyl methacrylate, and 5 parts by mass of methacrylic acid were added and stirred again. 0.3 parts by mass of azobisisobutyronitrile and 1 part by mass of n-dodecylmercaptan were added, and the temperature was raised to 75 ° C. Then, the reaction was carried out for 3 hours while maintaining the reaction temperature of 75 to 80 ° C. After confirming the maximum value of the heat generated by the polymerization, the temperature was raised to 95 ° C, and this state was maintained for 1 hour to terminate the reaction. The obtained aqueous suspension is meshed at 45 μm.
The mixture was filtered and washed with a nylon filter cloth of
Drying at 16 ° C. for 16 hours gave a granular vinyl polymer having an acid value of 31.9 mgKOH / g. Slight cloudiness was observed in a 30% by mass ethyl acetate solution of the obtained vinyl polymer, and insolubles precipitated.

[0031]

Comparative Example 2 In a polymerization apparatus capable of heating and cooling, 200 parts by mass of deionized water and polyvinyl alcohol (saponification degree 8
0%, polymerization degree 1,700) 0.6 parts by mass and stirred,
After the polyvinyl alcohol was completely dissolved, the stirring was stopped once, and 50 parts by mass of methyl methacrylate and 1 part of styrene were added.
0 parts by mass, 35 parts by mass of n-butyl methacrylate, and 5 parts by mass of methacrylic acid were added and stirred again. 0.3 parts by mass of azobisisobutyronitrile and 1 part by mass of n-dodecylmercaptan were added, and the temperature was raised to 75 ° C. The reaction was carried out for 2.5 hours while maintaining the reaction temperature of 75 to 80 ° C., and 1 part by mass of sodium polyoxyethylene alkyl ether sulfate was added.
After confirming the maximum value of the exothermic polymerization after 15 minutes, the temperature was raised to 95 ° C,
This state was maintained for 1 hour to terminate the reaction. The obtained aqueous suspension was filtered and washed with a nylon filter cloth having a mesh size of 45 μm, and the filtrate was dried at 40 ° C. for 16 hours to obtain a granular vinyl polymer having an acid value of 30.1 mgKOH / g.
The 30% by mass ethyl acetate solution of the obtained vinyl polymer became cloudy, and a large amount of insoluble matter was observed.

[0032]

According to the method for producing a granular vinyl polymer of the present invention, the content of emulsified fine particles as impurities is extremely reduced, and the obtained granular vinyl polymer has good odor and good solubility in various organic solvents. This is very useful industrially.

Claims (4)

[Claims] 1. A method for producing a granular vinyl polymer, wherein a surfactant is added after the polymerization exotherm during suspension polymerization has a maximum value. 2. The granular vinyl polymer contains a carboxyl group-containing vinyl monomer unit.
A method for producing a granular vinyl polymer according to claim 1. 3. The granular vinyl polymer has an acid value of 5 to 35.
The method for producing a granular vinyl polymer according to claim 1, wherein the amount is in the range of 0 mgKOH / g. 4. The method for producing a granular vinyl polymer according to claim 1, wherein the time for adding the surfactant is within one hour from the time when the heat generated by the suspension polymerization shows the maximum value.