JP5404222B2 - Method for producing vinyl polymer - Google Patents

Description

  The present invention relates to a method for producing a vinyl polymer.

The suspension polymerization method is one of polymerization methods for vinyl polymers, and is well known as a method for producing spherical vinyl polymer particles having a particle diameter of about 10 to 1000 μm in solid form. In this polymerization method, generally, a vinyl monomer containing an aqueous medium in which a dispersing agent is dissolved and a polymerization initiator is charged into a reactor equipped with a stirrer, and stirred and heated to form a solid vinyl system. A polymer is obtained.
The suspension polymerization method is widely used because it is easy to remove reaction heat because it is carried out in an aqueous medium and can easily produce a solid vinyl polymer. There is a drawback that the molecular weight is difficult to decrease.

Conventionally, when a low molecular weight vinyl polymer is produced by suspension polymerization, an initiator or a mercaptan chain transfer agent is frequently used, and the polymerization temperature is heated above the boiling point of the medium, and polymerization is performed under pressure. The method was general.
However, in this method, it is difficult to control the heat generation, and since a large amount of initiator and chain transfer agent are used, odor derived from the decomposed product of initiator, residual chain transfer agent, or residual vinyl monomer, and coating film performance There was a problem of deterioration.

  In Patent Documents 1 and 2, in order to solve the above-mentioned problem, a specific cobalt complex is used to solve the above-mentioned problem effectively by a catalytic chain transfer polymerization method (Catalytic Chain Transfer Polymerization, CCTP method). It is described that low molecular weight can be achieved.

Japanese Patent No. 3585730 Japanese Patent Publication No. 6-23209

However, even when a cobalt complex is used, when an azo initiator such as 2,2′-azobis (isobutyronitrile) described in Patent Document 1 is used, nitrogen derived from the initiator causes a specific gravity. There was a problem that a large amount of a light vinyl polymer and secondary agglomerates were generated, and the yield was remarkably lowered.
In addition, when benzoyl peroxide described in Patent Documents 1 and 2 is used, the chain transfer effect of the cobalt complex tends to decrease, and in order to obtain a target low molecular weight, the amount of cobalt complex is increased. As a result, there is a case where coloring of the vinyl polymer by the cobalt complex becomes a problem.
Therefore, in the present invention, a suspension polymerization method has been found in which a vinyl-based polymer that exhibits a high chain transfer effect at a high yield and has no coloring problem can be obtained by combining a cobalt complex and a specific initiator.

The gist of the present invention is that the vinyl monomer is represented by the formula (1) [in the formula (1), R _{1 to} R ₄ are each independently an alkyl group, a cycloalkyl group and an aryl group; Independently, F atom, Cl atom, Br atom, OH group, alkoxy group, aryloxy group, alkyl group and aryl group] and a cobalt complex represented by formula (2) and a peroxide initiator represented by formula (2) [In the formula (2), R and R ′ each independently represents a method for producing a vinyl polymer by suspension polymerization using an alkyl group, a cycloalkyl group, or an aryl group].

[In the formula (1), R _{1 to} R ₄ are each independently an alkyl group, a cycloalkyl group and an aryl group; X is each independently an F atom, a Cl atom, a Br atom, an OH group, an alkoxy group; Group, aryloxy group, alkyl group and aryl group]

[In Formula (2), R and R ′ are each independently an alkyl group, a cycloalkyl group, or an aryl group]
Moreover, as for the peroxide type initiator to be used, R is a C6-C12 alkyl group.

  Since the production method of the present invention has a higher chain transfer effect than the conventional suspension polymerization method, a low molecular weight vinyl polymer can be obtained even with a smaller amount of initiator, and polymerization can be performed with good yield. it can. Furthermore, the problem that the vinyl polymer derived from the cobalt complex is colored can be solved.

  Hereinafter, the present invention will be described in detail.

  As the cobalt complex used in the present invention, a cobalt complex represented by the formula (1) can be used. For example, Japanese Patent No. 3585730, Japanese Patent Publication No. 6-23209, Japanese Patent Publication No. 7-35411, US Pat. Publications, US Pat. No. 4,694,054, US Pat. No. 4,837,326, US Pat. No. 4,886,861, US Pat.

[In the formula (1), R _{1 to} R ₄ are each independently an alkyl group, a cycloalkyl group and an aryl group; X is each independently an F atom, a Cl atom, a Br atom, an OH group, an alkoxy group; Group, aryloxy group, alkyl group and aryl group]
Specifically, bis (borondifluorodimethyldioxyiminocyclohexane) cobalt (II), bis (borondifluorodimethylglyoxymate) cobalt (II), bis (borondifluorodiphenylglyoxymate) cobalt (II), vicinal Cobalt (II) complex of iminohydroxyimino compound, cobalt (II) complex of tetraazatetraalkylcyclotetradecatetraene, N, N′-bis (salicylidene) ethylenediaminocobalt (II) complex, dialkyldiazadioxodialkyldodeca Examples thereof include cobalt (II) complexes of diene and cobalt (II) porphyrin complexes. One or more of these can be appropriately selected and used. Among these, bis (borondifluorodiphenylglyoxymate) cobalt (II) (R _{1 to} R ₄ : phenyl group, X: F atom) which is stably present in an aqueous medium and has a high chain transfer effect is preferable.

  Although the usage-amount of a cobalt complex is not restrict | limited in particular, it is preferable to exist in the range of 0.0005-0.02 mass part with respect to 100 mass parts of vinylic monomers, 0.001-0.015 mass Is more preferably in the range of parts, and particularly preferably in the range of 0.002 to 0.01. When the usage-amount of a cobalt complex is 0.0005 mass part or more, it exists in the tendency for the molecular weight of a vinyl type polymer to fall efficiently. Moreover, if the usage-amount of a cobalt complex is 0.02 mass part or less, since coloring of the vinyl-type polymer by a cobalt complex will not be a problem, it is preferable.

In order to lower the molecular weight with the same initiator amount, it is necessary that the chain transfer effect is high. The chain transfer effect can be quantitatively expressed by determining the chain transfer constant Cs when each initiator is used.
That is,
1 / DPn = 1 / DPn, 0 + Cs [Co (II)] / [M] (Formula 3)
Dpn: degree of polymerization of vinyl polymer produced by polymerization in the presence of chain transfer agent Dpn, 0: degree of polymerization of vinyl polymer produced by polymerization in the absence of chain transfer agent Cs: chain transfer constant [Co (II)] / [M]: mol ratio of charged Co complex and vinyl monomer Reference: radical polymerization handbook, supervised by Mikiharu Tsunoike, TN Corporation, p. 38-48
The larger the Cs: chain transfer constant determined by (Equation 3), the lower the molecular weight even with the same initiator amount. Preferably, Cs is 2000 or more, more preferably 4000 or more.

As the polymerization initiator used in the present invention, a peroxide-based initiator represented by the formula (2) is used.
[In Formula (2), R and R ′ are each independently an alkyl group, a cycloalkyl group, or an aryl group]
Examples of the initiator of the formula (2) include 1,1,3,3-tetramethylbutylperoxy 2-ethylhexanoate (R: an alkyl group having 8 carbon atoms, R ′: an alkyl group having 7 carbon atoms) ), T-hexylperoxy 2-ethylhexanoate (R: alkyl group having 6 carbon atoms, R ′: alkyl group having 7 carbon atoms), t-amylperoxy 2-ethylhexanoate, t-butylper Oxy-2-ethylhexanoate (R: alkyl group having 4 carbon atoms, R ′: alkyl group having 7 carbon atoms), cumylperoxyneodecanoate, 1,1,3,3-tetramethylbutylperoxyneo Decanoate, t-hexylperoxyneodecanoate, t-butylperoxyneodecanoate, t-butylperoxyneoheptanoate, t-hexylperoxypivalate, t-butylper Xipivalate, 2,5-dimethyl-2,5-di (2-ethylhexanoylperoxy) hexane, 2,5-dimethyl-2,5-di (2-benzoylperoxy) hexane, t-butylperoxy- 3,5,5-trimethylhexanoate, t-butyl peroxylaurate, t-hexyl peroxybenzoate, and the like. One or more of these can be appropriately selected and used. Further, R in the formula (2) is not particularly limited, but is preferably an alkyl group having 6 to 12 carbon atoms. When R in Formula (2) is an alkyl group having 6 or more carbon atoms, the chain transfer effect tends to be higher, and when it is an alkyl group having 12 or less carbon atoms, coloring tends to be reduced. In addition, R ′ in the formula (2) is not particularly limited as long as it is an alkyl group, a cycloalkyl group, or an aryl group. Among them, 1,1,3,3-tetramethylbutylperoxy 2-ethylhexanoate (R: an alkyl group having 8 carbon atoms, R ′: an alkyl group having 7 carbon atoms), t-hexylperoxy 2-ethyl Hexanoate (R: an alkyl group having 6 carbon atoms, R ′: an alkyl group having 7 carbon atoms) is preferred.
The amount of the polymerization initiator used is not particularly limited, but is preferably in the range of 0.05 to 10 parts by mass, more preferably 0.1 to 5 parts by mass with respect to 100 parts by mass of the vinyl monomer. It is preferable to be within the range. When the amount of the polymerization initiator used is 0.05 parts by mass or more, the polymerization rate of the vinyl monomer is improved, and the vinyl polymer tends to be produced in a relatively short time. On the other hand, when the amount is 10 parts by mass or less, the polymerization exotherm is alleviated and the polymerization temperature tends to be easily controlled.

The suspension polymerization method may be performed under known conditions, for example, in JP-A-2006-282935. Below, an example of the manufacturing method of the vinyl-type polymer by suspension polymerization method is shown.
A vinyl monomer, a chain transfer agent, and a polymerization initiator are added to water containing a dispersant, suspended, and the aqueous suspension is heated to advance the polymerization reaction. The liquid is filtered, washed, dehydrated and dried. The resulting vinyl polymer is a solid particle.

  Examples of the vinyl monomer used in the present invention include methyl (meth) acrylate, ethyl (meth) acrylate, n-butyl (meth) acrylate, i-butyl (meth) acrylate, and t-butyl (meth). Acrylate, 2-ethylhexyl (meth) acrylate, n-lauryl (meth) acrylate, n-stearyl (meth) acrylate, cyclohexyl (meth) acrylate, phenyl (meth) acrylate, benzyl (meth) acrylate, isobornyl (meth) acrylate, (Meth) acrylic acid esters such as 2-methoxyethyl (meth) acrylate, 2-ethoxyethyl (meth) acrylate, phenoxyethyl (meth) acrylate; 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) Hydroxyl-containing (meth) acrylic acid esters such as acrylate, 4-hydroxybutyl (meth) acrylate, glycerol (meth) acrylate; (meth) acrylic acid, 2- (meth) acryloyloxyethylhexahydrophthalic acid, 2- (meth) ) Acryloyloxypropylhexahydrophthalic acid, 2- (meth) acryloyloxyethylphthalic acid, 2- (meth) acryloyloxypropylphthalic acid, 2- (meth) acryloyloxyethylmaleic acid, 2- (meth) acryloyloxypropyl Contains carboxyl groups such as maleic acid, 2- (meth) acryloyloxyethyl succinic acid, 2- (meth) acryloyloxypropyl succinic acid, crotonic acid, fumaric acid, maleic acid, itaconic acid, monomethyl maleate, monomethyl itaconate Nyl monomers; vinyl monomers containing acid anhydride groups such as maleic anhydride and itaconic anhydride; glycidyl (meth) acrylate, glycidyl α-ethyl acrylate, 3,4-epoxy (meth) acrylic acid Epoxy group-containing vinyl monomers such as butyl; amino group-containing (meth) acrylic ester vinyl monomers such as dimethylaminoethyl (meth) acrylate and diethylaminoethyl (meth) acrylate; (meth) acrylamide; Amide groups such as Nt-butyl (meth) acrylamide, N-methylol (meth) acrylamide, N-methoxymethyl (meth) acrylamide, N-butoxymethyl (meth) acrylamide, diacetone acrylamide, maleic acid amide, maleimide, etc. Contains vinyl monomers; styrene, α-methylstyrene, vinyl Vinyl monomers such as rutoluene, (meth) acrylonitrile, vinyl chloride, vinyl acetate, vinyl propionate, ethylene vinyl di (meth) acrylate, 1,3-butylene glycol di (meth) acrylate, 1,6- Hexanediol di (meth) acrylate, triethylene glycol di (meth) acrylate, tetraethylene glycol di (meth) acrylate, tripropylene glycol di (meth) acrylate, trimethylolpropane tri (meth) acrylate, allyl (meth) acrylate, And polyfunctional vinyl monomers such as N, N′-methylenebis (meth) acrylamide; One or more of these can be appropriately selected and used.

  In the present specification, “(meth) acrylate” means “acrylate and / or methacrylate”, “(meth) acrylic acid” means “acrylic acid and / or methacrylic acid”, and “(meth) “Acrylyl” means “acryloyl and / or methacryloyl”, “(meth) acrylonitrile” means “acrylonitrile and / or methacrylonitrile”, “(meth) acrylamide” means “acrylamide and / or methacrylamide”. means.

  The dispersant used in the present invention is not particularly limited. For example, poly (meth) acrylic acid alkali metal salts, alkali metal salts of copolymers of (meth) acrylic acid and methyl (meth) acrylate, ken Polyvinyl alcohol, methylcellulose and the like having a degree of conversion of 70 to 100% can be used. Although it does not restrict | limit especially as a quantity of a dispersing agent, It is preferable that it is 0.005-5 mass% in aqueous suspension, and it is still more preferable that it exists in the range of 0.01-1 mass%. When the amount of the dispersant used is 0.005% by mass or more, the dispersion stability of the suspension polymerization liquid is good, and the resulting vinyl polymer has good cleaning properties, dehydration properties, drying properties, and fluidity. There is a tendency. On the other hand, when the content is 5% by mass or less, there is little foaming during polymerization and the polymerization stability tends to be good. For the purpose of improving the dispersion stability of the aqueous suspension, an electrolyte such as sodium carbonate, sodium sulfate or manganese sulfate may be used.

  The polymerization temperature is not particularly limited, but is preferably 50 to 130 ° C, and more preferably 60 to 100 ° C. When the polymerization temperature is 50 ° C. or higher, the polymerization can be completed in a relatively short time, and the dispersion stability tends to be good during suspension polymerization. Further, when the temperature is 130 ° C. or lower, the polymerization exotherm is alleviated and the polymerization temperature tends to be easily controlled.

  The low molecular weight vinyl polymer obtained by the present invention is suitable for coatings and inks, particularly for high solid content organic solvent type coating resins, photocurable coating resins, or powder coating resins. Since it is obtained in a solid form, when it is used as an organic solvent-type coating composition or a photocurable coating composition, various types of organic solvents and vinyl monomers can be used at the time of dissolution. In addition, because it is a low molecular weight vinyl polymer, it retains low viscosity even when dissolved in organic solvents and vinyl monomers at high concentrations, and has excellent paintability. Can be adapted to.

  The Mw / Mn (weight average molecular weight / number average molecular weight) of the vinyl polymer produced according to the present invention is not particularly limited. For example, when used as a resin for an organic solvent-type paint, the Mw / Mn of the vinyl polymer is It is preferably 4 or less, more preferably 3 or less. When the Mw / Mn of the vinyl polymer is 4 or less, the solubility in various solvents tends to be improved.

Hereinafter, the present invention will be specifically described by way of examples, but the present invention is not limited thereto. In the following, “part” represents “part by mass”. Moreover, the measurement and evaluation of each physical property in the present examples and comparative examples were performed by the following methods.
(1) Yield The mass of the obtained normal vinyl polymer was measured, and the yield (%) was calculated from the following formula (4). The normal vinyl polymer means a net mass, and excludes aggregates adhering to the polymerization apparatus during polymerization, secondary aggregates containing air, and the like.
Yield (%) = mass of normal vinyl polymer (g) / mass of charged vinyl monomer (g) × 100 (4)
(2) Gardner color number 10 g of the obtained normal vinyl polymer was taken in a Gardner test tube and measured by colorimetry with a Gardner color number standard solution according to JIS K 5600.
(3) Molecular weight (Mw, Mn and Mw / Mn)
The gel permeation chromatography (GPC) “HLC-8120” (trade name, manufactured by Tosoh Corporation) was used for measurement. The column used was TSKgel G5000HXL * GMHXL-L (trade name, manufactured by Tosoh Corporation). The calibration curve was prepared using TSK standard polystyrene F288 / F80 / F40 / F10 / F4 / F1 / A5000 / A1000 / A500 (trade name, manufactured by Tosoh Corporation) and styrene.
Measurement was carried out at 40 ° C. using 100 μl of a solution obtained by dissolving the obtained normal vinyl polymer in tetrahydrofuran (THF) so as to be 0.4% by mass. The weight average molecular weight (Mw), the number average molecular weight (Mn), and the weight average molecular weight / number average molecular weight (Mw / Mn) were calculated in terms of standard polystyrene.
(4) Chain transfer constant Based on the molecular weight measurement result obtained in (3), the chain transfer constant Cs when each initiator was used was determined from (Equation 3).
1 / DPn = 1 / DPn, 0 + Cs [Co (II)] / [M] (Formula 3)
Dpn: degree of polymerization of vinyl polymer produced by polymerization in the presence of chain transfer agent Dpn, 0: degree of polymerization of vinyl polymer produced by polymerization in the absence of chain transfer agent Cs: chain transfer constant [Co (II)] / [M]: molar ratio of charged Co complex to vinyl monomer In this application, for each initiator, the values of 1 / DPn and [Co (II)] / [M] are plotted, and the slope thereof. From this, Cs was obtained.

Production Example 1 [Production of Dispersant 1]
In a polymerization apparatus equipped with a stirrer, a condenser, and a thermometer, 900 parts of deionized water, 60 parts of sodium 2-sulfoethyl methacrylate, 10 parts of potassium methacrylate and 12 parts of methyl methacrylate were stirred and polymerized. While the inside was replaced with nitrogen, the temperature was raised to 50 ° C. Into this, 0.08 part of 2,2′-azobis (2-methylpropionamidine) dihydrochloride was added as a polymerization initiator, and the temperature was further raised to 60 ° C. After the temperature increase, methyl methacrylate was continuously added dropwise at a rate of 0.24 part / minute for 75 minutes using a dropping pump. The reaction solution was held at 60 ° C. for 6 hours and then cooled to room temperature to obtain Dispersant 1 having a solid content of 10% by mass as a transparent aqueous solution.
Production Example 2 [Production of chain transfer agent 1]
In a synthesizer equipped with a stirrer, 1.00 g of cobalt (II) acetate tetrahydrate and 1.93 g of diphenylglyoxime, 80 ml of diethyl ether previously deoxygenated by nitrogen bubbling were added at room temperature. Stir for 30 minutes. Subsequently, 10 ml of boron trifluoride diethyl ether complex was added, and the mixture was further stirred for 6 hours. The mixture was filtered, and the solid was washed with diethyl ether and dried in vacuo for 15 hours to obtain 2.12 g of chain transfer agent 1 as a reddish brown solid.

[Example 1-a] [Production of vinyl polymer]
In a polymerization apparatus equipped with a stirrer, a condenser, and a thermometer, 145 parts of deionized water, 0.1 part of sodium sulfate and 0.25 part of dispersant 1 (solid content 10% by mass) were stirred and stirred uniformly. Solution. Next, 100 parts of methyl methacrylate, 0.005 part of chain transfer agent 1 and 0.05 part of 1,1,3,3-tetramethylbutylperoxy 2-ethylhexanoate were added, and an aqueous suspension was added. did. Next, the inside of the polymerization apparatus was purged with nitrogen, heated to 80 ° C., reacted for about 1 hour, and further heated to 90 ° C. as a post-treatment temperature and held for 1 hour in order to increase the polymerization rate. Thereafter, the reaction solution was cooled to 40 ° C. to obtain an aqueous suspension containing the polymer. This aqueous suspension was filtered through a nylon filter cloth having an opening of 45 μm, and the filtrate was washed with deionized water, dehydrated, and dried at 40 ° C. for 16 hours to obtain a vinyl polymer. This vinyl polymer was Mw 280000 and Mw / Mn 3.7.

The symbols in the table are as follows.
Perocta O: 1,1,3,3-tetramethylbutylperoxy 2-ethylhexanoate (manufactured by NOF Corporation)
Perhexyl O: t-hexyl peroxy 2-ethylhexanoate (manufactured by NOF Corporation)
Perbutyl O: t-butyl peroxy 2-ethylhexanoate (Nippon Yushi Co., Ltd.) LPO: Lauroyl peroxide BPO: Benzoyl peroxide AMBN: 2,2′-azobis (2-methylbutyronitrile)
AIBN: 2,2'-azobisisobutyronitrile Example 1-A through 2 -b, Example 3-a, 3-b, Comparative Example 1-a~4]
Except that the type and addition amount of the initiator are those shown in Tables 1 and 2, Example 1-
A vinyl polymer was obtained in the same manner as a. The evaluation results are shown in Tables 1 and 2.

In Examples 1-a to 2-b , a vinyl polymer having high yield and chain transfer effect and low coloration could be obtained.
On the other hand, in Comparative Examples 1-a and 1-b, since diacyl type peroxide-based initiators are used, Examples 1-c and 1-d using the same amount of cobalt complex respectively. In comparison, the chain transfer effect was low, and higher coloring was also observed. In Comparative Example 2-a and Comparative Example 2-b, since the diacyl type peroxide-based initiator was used, the same amount was used. Compared with Example 1-b and Example 1-c using a cobalt complex, the chain transfer effect was low and the yield was sometimes low.

  In Comparative Examples 3 and 4, since an azo-based initiator was used, the chain transfer effect was high as compared with Example 1-c using the same amount of cobalt complex, but the yield was remarkably low. .

Claims (1)

A vinyl monomer, using a peroxide open initiator represented by the cobalt complex represented by the following formula (1), and the following formula (2), to produce a vinyl polymer by suspension polymerization Method.

[In the formula (1), R _{1 to} R ₄ are each independently an alkyl group, a cycloalkyl group and an aryl group; X is each independently an F atom, a Cl atom, a Br atom, an OH group, an alkoxy group; Group, aryloxy group, alkyl group and aryl group]

[R in Formula (2) is an alkyl group having 6 to 12 carbon atoms, and R ′ is one substituent selected from the group consisting of an alkyl group, a cycloalkyl group, and an aryl group]