JPH0369924B2 - - Google Patents

Description

[Detailed description of the invention]

(Industrial Application Field) The present invention relates to a reaction inhibitor for radical polymerization, which is useful for producing vinyl polymers with reduced dyestuff and improved initial colorability and thermal stability, and a vinyl polymer using the same. This invention relates to a method for inhibiting monomer reactions. (Prior art) Conventionally, when radical polymerizing vinyl monomers,
A reaction inhibitor (also referred to as a reaction inhibitor) consisting of a phenol compound, a sulfur compound, an N-oxide compound, etc. is added to the polymerization system. Among these, phenolic compounds include, for example, 2,2-di-(4'-hydroxyphenyl)propane, hydroquinone, p-methoxyphenol, tert-butylhydroxyanisole,
n-octadecyl-3-(4-hydroxy-3,
5-di-tert-butylphenyl) propionate, 2,5-di-tert-butylhydroquinone,
4,4'-Butylidene-bis-(3-methyl-6-
tert-butylphenol), 3,5-di-tert-butyl-4-hydroxytoluene, 2,2'-methylene-bis-(4-ethyl-6-tert-butylphenol), triethylene glycol-bis[3 −
(3-tert-butyl-5-methyl-4-hydroxyphenyl)propionate], pentaerythrityl-tetrakis [3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], tert- Butylcatechol, 4,4'-thiobis-(6-tert-butyl-m-cresol), tocopherol, and the like are known. These reaction inhibitors are added to the polymerization system before the start of polymerization in order to reduce the buildup in the resulting polymer (Japanese Patent Application Laid-open No. 48-89990 and Japanese Patent Publication No. 60-50366). It is also added during the polymerization reaction to suppress heat shock, or added at the end of the polymerization reaction to prevent post-polymerization, or to prevent deterioration of initial colorability due to heat history (U.S. Pat. No. 3,642,756). Calligraphy, Tokukai Sho
57-185302 and 62-503). It is also used as an emergency reaction stopper in the event of an abnormal reaction. (Problem to be Solved by the Invention) However, even if these reaction inhibitors can solve the problems at each stage, they cannot sufficiently suppress or inhibit the polymerization reaction at another stage. It was not possible to satisfy all of the problems such as the quality of the polymer, such as its firmness, initial coloration, and thermal stability, or the adhesion of scale to the inner wall of the polymerization vessel. Therefore, an object of the present invention is to sufficiently suppress and inhibit the radical polymerization reaction of vinyl monomers, reduce stickiness, and produce a vinyl polymer with excellent initial coloring properties and thermal stability. The present invention aims to provide a reaction inhibitor for radical polymerization that can inhibit the reaction of vinyl monomers using the same. (Means for Solving the Problems) The reaction inhibitor for radical polymerization according to the present invention has the general formula (In the formula, R ¹ is an alkyl group having 3 to 10 carbon atoms,
R ² is a hydrogen atom or an alkyl group having 1 or more carbon atoms, and the alkyl group of either R ¹ or R ² or both is a tetramethylbutyl group)
This is a compound represented by In addition, the method for suppressing the reaction of vinyl monomers using this method allows the above-mentioned reaction to occur in the polymerization system at any one of the stages before the start of polymerization, during polymerization, and at the end of polymerization during radical polymerization in an aqueous medium. The gist of this is to add an inhibitor. To explain this, in the reaction inhibitor represented by the above general formula, R ¹ is an alkyl group having 3 to 10 carbon atoms, specifically n-propyl, isopropyl, butyl, tert-butyl, n-pentyl. ,tert
-pentyl, neopentyl, n-hexyl, 1,
1'-dimethylbutyl, n-heptyl, 1,1',3
-trimethylbutyl, n-octyl, 1,1',
3,3'-tetramethylbutyl, n-nonyl, 1-
Examples include ethyl-1',3,3'-trimethylbutyl, n-decyl, and 1,1',3,3'-tetramethylpentyl. In addition, R ² is a hydrogen atom,
or an alkyl group having 1 or more carbon atoms, such as a methyl or ethyl group and the same groups as explained for R ¹ above. And R ¹ and R ²
The alkyl group of either one or both of is required to be a tetramethylbutyl group. Among the compounds defined in this way, 2-(1,1',3,3'tetramethylbutyl)hydroquinone, 2,5-di(1,1',3,3'tetramethylbutyl)hydroquinone , or 2-(1,
1',3,3'tetramethylbutyl)-5-methylhydroquinone is preferred for achieving the objectives of the invention. The above-mentioned reaction inhibitor is particularly effective in the radical polymerization reaction of a vinyl monomer, which is a polymerizable olefinic monomer having at least one terminal group CH ₂ =C<; For example, vinyl halides or vinylidene halides such as vinyl chloride, vinyl bromide, and vinylidene chloride; acrylic acid esters such as methyl acrylate, ethyl acrylate, butyl acrylate, octyl acrylate, and cyanoethyl acrylate; methyl methacrylate, butyl methacrylate, etc. methacrylic acid ester; styrene and derivatives such as α-methylstyrene, vinyltoluene, chlorostyrene; vinyl acetate;
Examples include vinylnaphthalene; diolefins such as butadiene, isoprene, and chloroprene; and mixtures of these monomers with other copolymerizable olefin monomers. The reaction inhibitor of the present invention can be applied to any radical polymerization reaction of vinyl monomers, such as solution polymerization, emulsion polymerization, suspension polymerization, and bulk polymerization. Hereinafter, the method for suppressing the reaction of vinyl monomers according to the present invention will be explained using an example of suspension polymerization by radical reaction in an aqueous medium. The reaction inhibitor is added to the polymerization system at least one of the following stages: before the start of polymerization, during polymerization, and at the end of polymerization, depending on the purpose of use. The amount added is generally per 100 parts by weight of vinyl monomer.
It is about 0.0005 to 0.5 parts by weight. To explain this specifically, when added before polymerization for the purpose of reducing the fibers in the produced polymer, 0.0005
The amount is preferably 0.005 parts by weight. in this case,
It is more effective to prepare the aqueous medium by heating it in advance. When adding at the end of polymerization for the purpose of terminating the polymerization reaction when a predetermined polymerization addition rate is reached and preventing subsequent post-polymerization, the charged vinyl monomer
The amount is preferably 0.005 to 0.05 parts by weight per 100 parts by weight. When added to the polymerization system for the purpose of completely stopping the suspension polymerization reaction in an emergency, it is preferably added in an amount of 0.2 to 0.5 parts by weight per 100 parts by weight of the vinyl monomer charged. The method for adding this reaction inhibitor into the polymerization system is as follows:
It can be selected appropriately depending on the polymerization type, but
For example, it may be directly introduced into the polymerization system in liquid or powder form, or it may be dissolved or diluted with a solvent such as methanol or toluene and then introduced. It is also possible to prepare a suspension in which the reaction inhibitor is dispersed in water using an emulsifying agent, a suspending agent, etc., and to add the suspension to the polymerization system. Suspension polymerization in an aqueous medium is usually carried out at 0 to 100°C in the presence of a polymerization initiator and a dispersant. Dispersants used in this case include, for example, water-soluble cellulose ethers such as methylcellulose, hydroxyethylcellulose, hydroxypropylcellulose, and hydroxypropylmethylcellulose; partially saponified polyvinyl alcohol, acrylic acid polymer, polyvinylpyrrolidone, and maleic anhydride-vinyl acetate copolymer. Synthetic polymer compounds such as coalescence; natural polymer substances such as starch and gelatin;
Oil-soluble emulsifiers such as sorbitan monolaurate, sorbitan triolate, glycerol tristearate, and ethylene oxide propylene oxide block copolymer; water-soluble emulsifiers such as polyoxyethylene sorbitan monolaurate, polyoxyethylene glycerol oleate, and sodium laurate. These may be used alone or in combination of two or more. Examples of polymerization initiators include percarbonate compounds such as diisopropyl peroxydicarbonate, di-2-ethylhexyl peroxydicarbonate, and diethoxyethyl peroxydicarbonate; tert-butyl peroxypivalate, tert-hexyl peroxy pivalate, tert
-Perester compounds such as butylperoxyneodecanate and α-cumylperoxyneodecanate; acetylcyclohexylsulfonyl peroxide, 2,4,4-trimethylpentyl-2-
Peroxyphenoxy acetate, 3,5,5-
Peroxides such as trimethylhexanoyl peroxide; α,α′-azobisisobutyronitrile,
α,α′-azobis-2,4-dimethylvaleronitrile, α,α′-azobis(4-methoxy-2,4
- azo compounds such as dimethylvaleronitrile);
Furthermore, potassium persulfate, ammonium persulfate,
Examples include hydrogen peroxide, and these can be used alone or in combination of two or more. These polymerization initiators are usually charged vinyl monomers.
It is added in an amount of 0.03 to 0.3 parts by weight per 100 parts by weight. Other conditions during suspension polymerization in an aqueous medium, such as the aqueous medium in the polymerization vessel, the vinyl monomer, optionally other comonomers, dispersing aids,
There are no particular restrictions on the method of charging the polymerization initiator, their charging ratio, the polymerization temperature, etc., and the conditions normally used may be used. be done,
It is also optional to add polymerization degree regulators, chain transfer agents, PH regulators, gelling improvers, antistatic agents, antioxidants, scale inhibitors, and the like. (Examples) Hereinafter, specific aspects of the present invention will be explained using Examples and Comparative Examples, but the present invention is not limited thereto. (Production of vinyl polymer) Example 1 In an autoclave with an internal volume of 1.2 m ³ equipped with a stirrer,
600 kg of heated (60°C) water in which 150 g of partially saponified polyvinyl alcohol and 100 g of hydroxypropyl methylcellulose were dissolved was charged. Next, 4 g of 2-(1,1',3,3'tetramethylbutyl)hydroquinone was added to this, and then vinyl chloride was added.
400 kg was charged and stirred for 10 minutes at a temperature of 53°C to sufficiently disperse vinyl chloride in the polymerization system. after that,
200 g of di-2-ethylhexyl dicarbonate was added as a polymerization initiator, and the temperature of the polymerization system was raised to 57°C to initiate polymerization. The polymerization was terminated when the polymerization reaction approached completion and the internal pressure decreased to 6 kg/cm ² . After recovering unreacted monomers from the reaction mixture containing the produced polymer, the monomers were dehydrated and dried to obtain a polymer. Example 2 2-(1,1',3,3'-tetramethylbutyl)
Instead of hydroquinone, 2,5-di(1,
A polymer was obtained in the same manner as in Example 1, except that 4 g of 1',3,3'tetramethylbutyl)hydroquinone was used. Example 3 2-(1,1',3,3'-tetramethylbutyl)
Instead of hydroquinone, 2-(1,1′,3,
A polymer was obtained in the same manner as in Example 1, except that 4 g of 3'tetramethylbutyl)-5-methylhydroquinone was used. Comparative Example 1 A polymer was produced in the same manner as in Example 1, except that 4 g of 2,5-di-tert-butylhydroquinone was used instead of 2-(1,1',3,3'tetramethylbutyl)hydroquinone. I got it. Comparative Example 2 A polymer was obtained in the same manner as in Example 1, except that 4 g of tert-butylhydroxyanisole was used instead of 2-(1,1',3,3'tetramethylbutyl)hydroquinone. Comparative example 3 2-(1,1',3,3'-tetramethylbutyl)
A polymer was obtained in the same manner as in Example 1, except that no hydroquinone was used. (Various property tests on the obtained polymers) Each of the polymers obtained in Examples 1 to 3 and Comparative Examples 1 to 3 above was tested by the method shown below.
When we investigated the occurrence of fixing eyes due to roll forming (roll fixing eyes) and fixing eyes due to extrusion molding (extrusion fixing eyes), the initial coloring property, and the state of scale adhesion to the inner wall of the polymerization vessel, the results shown in Table 1 were obtained. Ta. Roll-Fish eye: Polymer produced 100 parts by weight DOP (dioctyl phthalate) 50 〃 Tribasic lead sulfate 0.5 〃 Lead stearate 1.5 〃 Titanium oxide 0.1 〃 Carbon black 0.05 〃 25 g of a compound prepared according to the above recipe of,
Knead for 5 minutes at 140℃ using a 6″ roll for kneading,
A sheet with a width of 10 cm and a thickness of 0.2 mm was molded. The number of transparent particles per 100 cm ² of the obtained sheet was counted, and this was used as an index of roll-fishing eye. Extrusion product: Polymer produced 100 parts by weight DOP (dioctyl phthalate) 50 Epoxidized soybean oil 3.0 Dioctyltin mercaptoacetate Colorant (blue) 0.002 The mixture prepared according to the above recipe was mixed in a Henschel mixer. Mix for 10 minutes at 120℃ using
The resulting mixture was processed using an extruder to a width of 4 cm and a thickness of 4 cm.
It was molded into a 0.5mm film. For this film, the number of transparent particles with a diameter of 0.3 mm or more per 1 kg of film was counted, and this was used as an index for extrusion fixation. Initial coloration: Produced polymer 100 parts by weight DOP (dioctyl phthalate) 50 Dibutyltin rallate 1.0 After kneading the blend prepared according to the above recipe at 160°C for 5 minutes using a 6″ roll, It was molded into a sheet.The obtained sheet was heated at 160℃ for 5 minutes.
Press for minutes to form into 5 cm x 5 cm x 1 cm (thickness), and the degree of coloring of the molded product is B if it is on par with general products.
Those that were better than this were designated as A, and those that were worse were designated as C and D, respectively. Condition of scale adhesion to the inner wall of the polymerization vessel: After washing the inside of the polymerization vessel with pure water, it was visually observed. The condition was evaluated based on the following criteria. A: There is almost no scale adhesion on the inner surface of the polymerization vessel. B: Scale was attached to the gas-liquid interface on the inner surface of the polymerization vessel. C: Scale was adhered to the entire inner surface of the polymerization vessel.

[Table] However, in the table: 2-(1,1',3,3'tetramethylbutyl)
Hydroquinone: 2,5-di(1,1',3,3'tetramethylbutyl) Hydroquinone: 2-(1,1',3,3'tetramethylbutyl)
-5-Methylhydroquinone: 2,5-di-tert-butylhydroquinone: Indicates tert-butylhydroxyanisole. (Manufacture of vinyl polymer) Example 4 150 g of partially saponified polyvinyl alcohol and 100 g of hydroxypropyl methylcellulose were mixed with 600 g of water.
The suspension obtained by dissolving in Kg was charged into an autoclave with an internal volume of 1.2 m ³ equipped with a stirrer. Next, 400 kg of vinyl chloride and 200 g of di-2-ethylhexyl dicarbonate were charged and stirred sufficiently, and then the temperature inside the polymerization system was raised to 57°C, and polymerization was carried out while stirring was continued. When the polymerization reaction approaches completion and the internal pressure drops to 6Kg/ ^cm2 , 2-(1,1',
3,3'tetramethylbutyl)hydroquinone 120
g was added, the temperature of the polymerization system was raised to 80℃,
Unreacted monomers were recovered from the polymerization system. After maintaining the temperature of the polymerization system at 80° C. for 30 minutes, it was cooled, and the reaction mixture containing the produced polymer was dehydrated and dried to obtain a polymer. Comparative Example 4 A polymer was produced in the same manner as in Example 4, except that 120 g of 2,5-di-tert-butylhydroquinone was used instead of 2-(1,1',3,3'tetramethylbutyl)hydroquinone. I got it. Comparative Example 5 Same as Example 4 except that 120 g of 2,2-di(4'-hydroxyphenyl)propane was used instead of 2-(1,1',3,3'tetramethylbutyl)hydroquinone. A polymer was obtained. Comparative Example 6 A polymer was obtained in the same manner as in Example 4, except that 2-(1,1',3,3'tetramethylbutyl)hydroquinone was not used at all. (Various property tests on the obtained polymers) The initial colorability of each of the polymers obtained in Example 4 and Comparative Examples 4 to 6 above was tested in the same manner as above, and in the method shown below. Plasticizer absorption (dry up) and thermal stability were measured. The results are shown in Table 2. Plasticizer absorption: 400 g of the polymer was put into a planetary mixer (jacket temperature: 83° C.) of Plasticoder manufactured by Prabender, and after heating for 4 minutes while kneading at 60 r/m, 200 g of DOP was added. The time from when the kneading torque of the planetary mixer reached its minimum from the time of addition of DOP was defined as the dry-up time, and was used as an index of plasticizer absorption. Thermal stability: The rolled sheet prepared in the evaluation of the initial colorability described above was placed in an oven with an internal temperature of 185° C., and the time until the rolled sheet completely blackened was measured.

[Table] However, in the table and the same as in Table 1, :2,2-di(4'-hydroxyphenyl)propane. (Production of vinyl polymer) Example 5 In an autoclave with an internal volume of 1.2 m ³ equipped with a stirrer,
600 kg of water in which 150 g of partially saponified polyvinyl alcohol and 100 g of hydroxypropyl methylcellulose were dissolved was charged. Next, 400 kg of vinyl chloride and 200 g of di-2-ethylhexyl dicarbonate were charged and stirred sufficiently, and then the temperature inside the polymerization system was raised to 57°C, and polymerization was carried out while stirring was continued. Two hours after starting the polymerization, 2-(1,
1200 g of 1',3,3'tetramethylbutyl)-5-methylhydroquinone was added, and it was confirmed that the polymerization reaction had been completely stopped. Comparative example 7 2-(1,1',3,3'tetramethylbutyl)-5
-An attempt was made to stop the polymerization reaction in the same manner as in Example 5, except that 1200 g of 2,2-di(4'-hydroxyphenyl)propane [bisphenol A] was used instead of methylhydroquinone. Although the reaction was significantly suppressed, it did not stop completely. In the above, it was determined that the polymerization reaction had completely stopped when the jacket temperature of the polymerization vessel completely exceeded the temperature of the reaction mixture (57°C). (Effects of the Invention) By adding the reaction inhibitor of the present invention to the polymerization system before the start of polymerization, it is possible to reduce the stickiness of the obtained polymer and improve the initial coloring property, as well as to prevent it from forming on the inner wall of the polymerization vessel. By adding it to the polymerization system during the polymerization reaction, it can improve the plasticizer absorption and thermal stability of the resulting polymer; At the end of polymerization Or as an emergency reaction terminator, it can stop the polymerization reaction more completely than conventional ones; etc. It can effectively suppress or stop the reaction of vinyl monomers, especially when suspended in an aqueous medium. Useful for inhibiting or stopping turbidity polymerization.

Claims (1)

[Claims] 1. General formula (In the formula, R ¹ is an alkyl group having 3 to 10 carbon atoms,
R ² is a hydrogen atom or an alkyl group having 1 or more carbon atoms, and the alkyl group of either R ¹ or R ² or both is a tetramethylbutyl group)
A radical polymerization inhibitor represented by: 2 When radically polymerizing a vinyl monomer in an aqueous medium, the general formula (In the formula, R ¹ is an alkyl group having 3 to 10 carbon atoms,
R ² is a hydrogen atom or an alkyl group having 1 or more carbon atoms, and the alkyl group of either R ¹ or R ² or both is a tetramethylbutyl group)
A reaction inhibitor represented by
A method for inhibiting the reaction of a vinyl monomer, which method comprises adding the vinyl monomer to a polymerization system. 3 The reaction inhibitor is 2-(1,1',3,3'-tetramethylbutyl)hydroquinone, 2,5-di(1,1',3,3'-tetramethylbutyl)hydroquinone, or 2- The reaction inhibitor for radical polymerization according to claim 1, which is (1,1',3,3'-tetramethylbutyl)-5-methylhydroquinone. 4 The reaction inhibitor is 2-(1,1',3,3'-tetramethylbutyl)hydroquinone, 2,5-di(1,1',3,3'-tetramethylbutyl)hydroquinone, or 2- 3. The method for inhibiting the reaction of a vinyl monomer according to claim 2, which is (1,1',3,3'-tetramethylbutyl)-5-methylhydroquinone.