JPH06184202A - Production of acrylic copolymer extremely low in residual content of monomer - Google Patents

Abstract

PURPOSE:To obtain a copolymer extremely low in residual content of monomer at a low cost by copolymerizing various vinylic monomers containing ethyl acrylate or their mixture with an alkyd resin, polyester resin, etc., in the presence of a radical polymerization initiator in a specific polymerization vessel. CONSTITUTION:Various vinylic monomers comprising butyl acrylate, methyl methacrylate, beta-hydroxyethyl acrylate, methacrylic acid, styrene, etc., containing >=10wt.% of ethyl acrylate, or the mixture of an alkyd resin or polyester resin with the monomers containing >=10wt.% of the ethyl acrylate are charged to an autoclave equipped with a stirrer, a thermometer, a pressure gauge, nitrogen gas-charging and discharging pipes, a heating and cooling jacket, and a cooling coil, and subsequently copolymerized in the presence of a radical polymerization initiator (e.g. ditertiary butyl peroxide) under a pressure of >=3kg/cm<2> to provide the objective acrylic copolymer extremely low in monomer at a low cost.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing an acrylic copolymer (hereinafter referred to as an extremely low residual monomer acrylic copolymer) having a very low residual ethyl acrylate monomer concentration and an extremely low ethyl acrylate monomer odor. It is a thing.

[0002]

2. Description of the Related Art The odor of ethyl acrylate monomer is particularly uncomfortable for humans among various monomers, and even if a very small amount is mixed in the resin, the working environment is improved during the transfer of the resin and the measurement of the work. Make it significantly worse. Therefore, there is a demand for an acrylic copolymer containing no ethyl acrylate monomer or having a significantly low ethyl acrylate monomer concentration. Therefore, a general method for producing an acrylic copolymer as a method for producing an extremely low residual monomer acrylic polymer (a predetermined polymerization solvent is supplied into the atmospheric pressure reactor to raise the internal temperature of the reactor to 80 to 120 ° C.). After that, a predetermined vinyl monomer and a radical polymerization initiator are fed into the vessel for 3 to 6 hours to carry out a polymerization reaction.
The residual monomer is polymerized by stirring at 120 ° C. for 3 to 5 hours. At this time, a small amount of radical polymerization initiator may be further added to facilitate the reaction of the residual monomer. )
After completion of the polymerization, in order to further reduce the residual monomer of ethyl acrylate, the ethyl acrylate is evaporated together with the polymerization solvent to reduce the residual monomer of ethyl acrylate, or after the completion of the polymerization reaction, it is mixed with ethyl acrylate. A method of reducing the residual monomer of ethyl acrylate by adding an easily boiling solvent and then azeotropically boiling the solvent with ethyl acrylate is used. The solvent used in this case is not limited to an organic solvent, and water may be used.

[0003]

However, in the above method, it is necessary to treat the mixture of the residual monomer and the solvent which is azeotropically produced, and the production cost of the extremely low residual monomer acrylic polymer becomes high. Further, when it is azeotropically distilled with water, it is necessary to treat the water that comes out, so that a water treatment facility is required, which increases the production cost of the extremely low residual monomer acrylic polymer.

[0004]

Means for Solving the Problems The inventors of the present invention have conducted diligent research to eliminate the above-mentioned defects in the conventional method, and as a result, an extremely low residual monomer acrylic polymer can be obtained by carrying out the polymerization under pressure. This has led to the completion of the present invention. That is, the method for producing an extremely low residual monomer acrylic polymer of the present invention is a copolymer of various vinyl monomers containing 10% by weight or more of ethyl acrylate and a copolymer of various vinyl monomers containing 10% by weight or more of acrylic acid. In the method for producing a resin in which coalesce and alkyd resin or polyester resin are modified, the pressure inside the reactor is set to 3 kg / cm ² G
The present invention relates to a method for producing an extremely low residual monomer acrylic copolymer, which is characterized in that the above is maintained and a radical initiator is used for copolymerization.

In the present invention, the extremely low residual monomer acrylic copolymer means an acrylic copolymer containing less than 1% of ethyl acrylate monomer. 1 ethyl acrylate monomer
If it is more than 0.1%, the odor is strong, and as described above, it gives off feeling to human beings, and the deterioration of the working environment becomes a problem.

In the present invention, the reactor used for producing the acrylic copolymer may be, for example, a corrosion-resistant autoclave. This reactor is described in detail as an autoclave having a pressure gauge, a stirrer, a heating / cooling jacket and a cooling internal coil. In the present invention, kg / cm ² G indicates the gauge pressure in the reactor, and the normal pressure is 0 kg / cm ² G. The reaction raw material mixture and the radical polymerization initiator are supplied to this reactor from a storage tank of the reaction raw material mixture and a dissolution tank of the radical polymerization initiator at a predetermined time by a metering pump. The temperature inside the reactor is maintained at a preset temperature by cascade control or the like, and the heat of polymerization generated as the polymerization proceeds can be removed by the jacket and the internal coil. The reactor was purged of air remaining in the reactor with nitrogen gas,
Further, it is pressurized to 1 kg / cm ² G or more with nitrogen gas before use.

In the present invention, the method for producing the acrylic copolymer will be described in detail. By using a solvent having a boiling point lower than that of ethyl acrylate as the reaction solvent, the residual monomer of ethyl acrylate can be further reduced. The reaction temperature is 50 to 250 ° C, preferably 80 to 200 ° C. The reaction pressure is 1 to 15 kg / cm ² G, preferably 3 to 7 kg / cm ² G
Is. Various vinyl monomers containing 10% by weight or more of ethyl acrylate are supplied to the above reactor together with a radical initiator to carry out solution polymerization at a predetermined pressure. Alternatively, a mixture of various vinyl monomers containing 10% by weight or more of ethyl acrylate and an alkyd resin or a polyether resin is supplied together with a radical initiator to carry out solution polymerization at a predetermined pressure. After supplying the reaction raw materials and radical initiator, the internal pressure should be 3 kg / cm ² G or more.
By keeping at g / cm ² G or more and stirring at 50 to 250 ° C., preferably 80 to 200 ° C. for 1 to 10 hours, preferably 2 to 5 hours, the target extremely low residual monomer acrylic polymer is obtained. It can be manufactured easily and completely. The acrylic copolymer thus obtained has an extremely low monomer concentration of ethyl acrylate, and therefore becomes an extremely low residual monomer acrylic polymer with extremely low odor of ethyl acrylate monomer.

The extremely low residual monomer acrylic polymer produced by such a method has a wide range of uses as a coating resin and an adhesive. For example, a copolymer of vinyl monomers containing a hydroxyl group can be cured with a melamine resin to form a tough film, or a polyisocyanate can be used as a curing agent to form a film with urethane crosslinks. You can Further, a copolymer of vinyl monomers containing a glycidyl group is an amine,
It can also be used as a binder in combination with a curing agent selected from polycarboxylic acids and polyester resins having terminal acid groups. Furthermore, the copolymer of a vinyl monomer containing an acid group can form a tough film by a curing reaction with a polyepoxide, and one or more compounds selected from the group consisting of ammonia and organic amines. It is possible to neutralize a part or all of the copolymer and dissolve it in water to use it as a binder for heavy-duty coating composition, or to use it as a dispersant for soap-free emulsion. it can.

The solvent used in carrying out the method of the present invention is an aromatic solvent represented by xylene or toluene, a naphthene solvent represented by cyclohexane, and a paraffin solvent represented by normal hexane. Solvents, ester solvents represented by ethyl acetate, isopropyl acetate or n-butyl acetate, ketone solvents represented by methyl ethyl ketone, methyl isobutyl ketone or cyclohexanone, cellosolves represented by methyl cellosolve, ethyl cellosolve, butyl cellosolve, etc. Typical examples are alcohol solvents such as methyl alcohol, ethyl alcohol, isopropyl alcohol, ithibutyl alcohol, and normal butyl alcohol. However, the use of an alcohol-based solvent is not limited to the use of a (meth) acrylate-based monomer or a functional group-containing monomer, a hydroxyl group-containing monomer and a glycidyl group-containing monomer, or an ethylenically unsaturated dicarboxylic acid diester, or a monocarboxylic acid. When a monomer such as vinyl ester is used, an ester exchange reaction occurs between each of these monomers and the alcohol solvent, and as a result, a copolymer having desired coating performance cannot be obtained. In such a case, the use of alcoholic solvents alone should be avoided. However, it is perfectly acceptable to use the alcoholic solvent in an amount that does not cause transesterification reaction or esterification reaction with respect to various vinyl monomers, alkyd resins and polyester resins.

Next, as the vinyl monomer, representative examples of acrylic acid ester or methacrylic acid ester components are methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate, butyl acrylate, and methacrylic acid. Butyl acrylate, isobutyl acrylate, isobutyl methacrylate, acrylic acid-2
-Ethylbexyl, 2-ethylbexyl methacrylate, lauryl acrylate or lauryl methacrylate. Typical examples of the aromatic vinyl monomer component include styrene, α-methylstyrene and vinyltoluene. Representative examples of the diester component of ethylenically unsaturated dicarboxylic acid,
Examples include dibutyl fumarate, dimethyl fumarate, and dibutyl itaconate. Examples of the hydroxyl group-containing vinyl monomer include β-hydroxyethyl acrylate, β-hydroxyethyl methacrylate, β-hydroxypropyl methacrylate, β-hydroxyisopropyl methacrylate and the like. Next, a typical glycidyl group-containing vinyl monomer is glycidyl methacrylate or glycidyl acrylate. Typical examples of the acid group-containing vinyl monomer include acrylic acid, methacrylic acid, fumaric acid, maleic acid and itaconic acid. Further representative examples of vinyl esters of monocarboxylic acids include vinyl acetate, vinyl propionate,
Examples include vinyl laurate and vinyl benzoate.

Furthermore, typical examples of diols and polyols useful in synthesizing polyester resin include glycerin, ethylene glycol,
1,4-butanediol, 1,6-hexanediol,
Trimethylolethane, trimethylolpropane, pentaerythritol or mixtures thereof. On the other hand,
Examples of useful acid components include succinic acid, adipic acid, azelaic acid, sebacic acid, decane-1,10-dicarboxylic acid,
It is terephthalic acid, isophthalic acid, phthalic anhydride, or a mixture thereof, and itaconic acid, fumaric acid, or maleic acid is used as the acid component having a double bond as a grafting point.

Next, representative examples of oil and fat components useful for producing a graftable alkyd resin include soybean oil, castor oil, dehydrated castor oil, tall oil, linseed oil or safflower oil. It is an oil or a fatty acid of the oil, and these can be used as one kind or as a mixed oil of two or more kinds. As the useful acid component and polyol component, those used for the synthesis of the above polyester resin can be used as they are.

The radical polymerization initiator used in the present invention includes organic oxide type and azo compound type.
Examples of organic peroxides include hydrogen peroxide, hydroperoxides, dialkyl peroxides, diacyl peroxides, ketone peroxides, alkyl peroxides, peroxydicarbonates and the like. In addition to nitriles represented by 2,2′-azobisisobutyronitrile and other nitriles, azo compounds include amidines, alkyls, alicyclics and the like.

[0014]

EXAMPLES Next, the present invention will be specifically described by way of examples. In the following, all parts and percentages are by weight unless otherwise specified.

Example 1 A main reactor was a 5 liter autoclave having a pressure resistant structure composed of a stirrer, a thermometer, a pressure gauge, a nitrogen gas introduction pipe and a discharge pipe, a heating and cooling jacket, and a cooling coil. Using a device such as a metering pump that quantitatively supplies the vinyl monomer mixture and a metering pump that quantitatively supplies the dissolved solution of the radical initiator, first purge the inside of the autoclave with nitrogen, and then the internal pressure is 5 kg / cm. Supply nitrogen gas to ² G. Then, in an autoclave, 30 parts of butyl cellosolve and 10 parts of isopropyl alcohol were used as the initial reaction liquid.
Part, and heat from the jacket to increase the temperature inside the reactor.
Hold at 150 ° C. The pressure inside the vessel was 6 kg / cm ² G due to the addition of the vapor pressure of the solvent, and this pressure was maintained. Then, in the container thus held, 25 parts of ethyl acrylate, 5 parts of butyl acrylate and 34 parts of methyl methacrylate were placed.
Part, 18 parts of β-hydroxyethyl acrylate, 7 parts of methacrylic acid, 11 parts of styrene, a vinyl monomer mixture, 10 parts of butyl cellosolve, 1 part of di-tert-butyl peroxide, 1 part of tert-butyl peroxy 2-ethyl hexaate. The mixture of the radical polymerization initiator consisting of was continuously fed for 4 hours by a metering pump, and then the reaction was continued for another 3 hours. Then, the contents of the reactor were cooled, the produced acrylic copolymer was taken out, and ethyl acrylate in the resin was quantitatively analyzed by gas chromatography. The results are shown in Table 1.

Comparative Example 1 Stirrer, thermometer, nitrogen gas inlet pipe, Dimroth opened to the atmosphere, 5 liter 4-necked flask, oil bath, jack for moving oil bath up and down to keep temperature inside the reactor, and temperature controller As the main reactor,
Further, using a device such as a quantitative pump for quantitatively supplying the vinyl monomer mixture to the flask and a quantitative pump for quantitatively supplying the solution of the radical polymerization initiator, the inside of the flask was replaced with nitrogen gas. Then, an initial reaction liquid was charged in the same manner as in Example 1, and the temperature inside the reactor was maintained at 110 ° C. in an oil bath. The pressure inside the reactor is 0 kg / c because it is desired to be released to the atmosphere via the Jimroth.
Equivalent to m ² G. Then, in the same manner as in Example 1, the vinyl monomer and the radical initiator were supplied and polymerized in the container thus held. The product was subjected to the same quantitative analysis as in Example 1. The results are shown in Table 1.

Example 2 The same operation as in Example 1 was repeated except that the following conditions were changed. Reaction temperature 170 ° C. Reaction pressure 6 kg / cm ² G Reaction initial liquid xylene 40 parts Monomer mixture styrene 30 parts Ethyl acrylate 48 parts Methyl acrylate 6 parts β-Hydroxyethyl acrylate 10 parts Dibutyl fumarate 6 parts Radical polymerization initiator mixture Solution Ditertiary butyl peroxide 1 part Quinn hydroperoxide 0.5 part Butyl acetate 10 parts The product was subjected to the same quantitative analysis as in Example 1. The results are shown in Table 1.

Comparative Example 2 The same operation as in Comparative Example 1 was repeated except that the following conditions were changed. Reaction temperature 100 ° C. Reaction pressure 0 kg / cm ² G Reaction initial solution, monomer mixture and radical polymerization initiator are the same as in Example 2, but a radical polymerization initiator is further added to react the residual monomer at 100 ° C. Three
Reacted for hours. The product was subjected to the same quantitative analysis as in Example 1. The results are shown in Table 1.

[Table 1] Odor evaluation method: Expressed by the number of people who felt the odor during handling by 10 workers. ◎ Number of people who felt the smell of ethyl acrylate 0 people ○ Number of people who felt the smell of ethyl acrylate 1-2 people △ Number of people who felt the smell of ethyl acrylate 3-5 people × Number of people who felt the smell of ethyl acrylate 6 or more tables From 1, it was found that the concentration of ethyl acrylate in the acrylic copolymer was remarkably reduced by polymerizing under the pressure of 3 kg / cm ² G or more in the reactor. Regarding the odor, the odor of ethyl acrylate was hardly sensed in the examples, but the odor of ethyl acrylate was strong in the comparative examples.

[0019]

EFFECTS OF THE INVENTION According to the present invention, there is no reduction in productivity due to unnecessary addition of an azeotropic solvent or extension of reaction time, and even when a very small amount is mixed in the resin, the resin is transferred and measured. As a result, an acrylic copolymer having an extremely low concentration of ethyl acrylate monomer, which gives unpleasant feelings during the work such as the above and significantly deteriorates the working environment, was obtained.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Takeshi Iwaki Mitsui Toatsu Kagaku Co., Ltd. 1-6 Takasago, Takaishi-shi, Osaka

Claims (1)

[Claims] 1. A copolymer obtained by reacting various vinyl monomers containing 10% by weight or more of ethyl acrylate or various vinyl monomers containing 10% by weight or more of ethyl acrylate with an alkyd resin or polyester resin. In the method for producing a copolymer, the pressure inside the reactor is kept at 3 kg / cm ² G or more, and the radical initiator is used for the copolymerization to produce an extremely low residual monomer acrylic copolymer. Method.