JP2021017482A - Method of producing vinyl polymer - Google Patents

Abstract

To provide a method of producing a vinyl polymer with a short time and a saved energy by a solution polymerization method.SOLUTION: The method of producing a vinyl polymer by a solution polymerization method for polymerizing while feeding a vinyl monomer in a solvent includes a temperature-rising process of polymerizing a vinyl monomer while rising a temperature, and a temperature-maintaining process of continuing the polymerization at a constant temperature after the temperature-rising process, where the amount of the vinyl monomer fed in the temperature rising process is 10-40 mass% of the vinyl monomer used for the production.SELECTED DRAWING: None

Description

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

Vinyl-based polymers obtained by polymerizing vinyl monomers are used in the fields of paints, pressure-sensitive adhesives, coating agents, and the like. As a method for producing a vinyl-based polymer, for example, Patent Document 1 and Patent Document 2 disclose solution polymerization in which a vinyl monomer is polymerized in a solvent.

Patent Document 1 discloses a method for producing a vinyl-based polymer by a dropping polymerization method in which a vinyl monomer is dropped into a solvent at a predetermined polymerization temperature. This method has a problem that it takes a long time to manufacture and consumes a large amount of energy for heating the solvent.
Patent Document 2 discloses a method for producing a vinyl-based polymer by a dropping polymerization method in which a vinyl monomer is dropped into a solvent only when the temperature is raised. This method has a problem that it is difficult to handle because the viscosity of the obtained vinyl polymer solution is high.

Japanese Unexamined Patent Publication No. 2004-18791 Japanese Unexamined Patent Publication No. 52-155691

An object of the present invention is to provide a method for producing a low-viscosity vinyl-based polymer solution by a solution polymerization method in a short time and with energy saving.

The present invention is a method for producing a vinyl-based polymer by a solution polymerization method in which a vinyl monomer is polymerized while being supplied to a solvent, in which a temperature raising step of polymerizing the vinyl monomer while raising the temperature of the solvent and a temperature raising are performed. Production of a vinyl-based polymer, which includes a temperature maintenance step of continuing polymerization at a constant temperature after the step, and the amount of vinyl monomer supplied in the temperature raising step is 10 to 40% by mass of the vinyl monomer used in the production. It's about the method.

According to the method for producing a vinyl-based polymer of the present invention, a low-viscosity vinyl-based polymer solution can be produced in a short time and with energy saving.

Hereinafter, the present invention will be described in detail.
In the method for producing a vinyl polymer of the present invention, solution polymerization is carried out while supplying a vinyl monomer to a solvent.

<Vinyl monomer>
The vinyl monomer used in the present invention is appropriately selected according to the vinyl-based polymer to be produced. The vinyl monomer used may be used alone or in combination of two or more. Examples of the vinyl monomer include a monomer having an acid group, a monomer having a hydroxyl group, a (meth) acrylic acid ester having a hydrocarbon substituent, a styrene-based monomer, an ethylenically unsaturated nitrile, a vinyl ester, and an epoxy group-containing vinyl. Examples thereof include a monomer, an ethylenically unsaturated basic vinyl monomer, and an α, β-unsaturated vinyl monomer having an N-alkoxyalkyl substituted amide group. Among these, styrene-based monomers and / or acrylic-based monomers among the above-mentioned vinyl monomers are preferably used as raw materials for vinyl-based polymers used in paints, adhesives, coating agents, and the like.

Examples of the monomer having an acid group include monobasic acid such as methacrylic acid, acrylic acid, crotonic acid, vinyl benzoic acid, fumaric acid, itaconic acid, maleic acid and citraconic acid, vinyl dibasic acid monomer, maleic anhydride and the like. Dibasic acid anhydride vinyl monomer, β-carboxyethyl (meth) acrylate, β-carboxypropyl (meth) acrylate, β- (meth) acryloxyethyl acid succinate, β- (meth) acryloxyethyl acid maleate , Β- (meth) acryloxyethyl acid phthalate, β- (meth) acryloxiethyl acid hexahydrophthalate, β- (meth) acryloxyethyl acid methyl hexahydrophthalate, γ- (meth) acryloxipropyl acid succinate , End of ring-opening adduct of ε-caprolactone or γ-butyrolactone to 2-hydroxyethyl (meth) acrylate (eg, "Plaxel® F" manufactured by Daicel Co., Ltd., "Tone M" manufactured by Dow Chemical Co., Ltd.) Caprolactone-modified hydroxyl groups such as succinic acid monoesters, phthalic acid monoesters, or hexahydrophthalic anhydride monoesters in which the hydroxyl groups are esterified with succinic anhydride, phthalic anhydride, or hexahydrophthalic anhydride and a carboxyl group is introduced at the ends. Long-chain carboxyl group-containing vinyl monomers such as monoester reaction products of containing (meth) acrylic acid ester and dibasic acid anhydride, monomethyl maleate, monoethyl maleate, monobutyl maleate, monooctyl maleate, monomethyl itacone , Monoethyl itaconate, monobutyl itaconate, monooctyl itaconate, mono2-ethylhexyl itaconate, monomethyl fumarate, monoethyl fumarate, monobutyl fumarate, monooctyl fumarate, monoethyl citrate and other dibasic acids or dibasic acids Examples thereof include monoesterides of anhydrous vinyl monomers.

Examples of the monomer having a hydroxyl group include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, and 4-hydroxybutyl ( (Meta) acrylic acid ester having a hydroxyalkyl group such as meta) acrylate and 6-hydroxyhexyl (meth) acrylate, β-butyrolactone ring-opening addition to 2-hydroxyethyl (meth) acrylate, 2-hydroxyethyl (meth) ) Ε-caprolactone ring-opening adduct to acrylate, ethylene oxide ring-opening adduct to (meth) acrylic acid, propylene oxide ring-opening adduct to (meth) acrylic acid, 2-hydroxyethyl (meth) acrylate or Other hydroxyl group-containing vinyl monomers such as (meth) acrylic acid esters, 4-hydroxybutyl vinyl ether, and p-hydroxystyrene having a hydroxyl group at the end of 2-hydroxypropyl (meth) acrylate dimer and trimerate. And so on.

Examples of the (meth) acrylic acid ester having a hydrocarbon substituent include methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, n-butyl (meth) acrylate, and i-butyl (meth). ) Acrylate, t-butyl (meth) acrylate, sec-butyl (meth) acrylate, n-pentyl (meth) acrylate, n-octyl (meth) acrylate, lauryl (meth) acrylate, stearyl (meth) acrylate, tridecyl (meth) ) Acrylate, 2-ethylhexyl (meth) acrylate, cyclohexyl (meth) acrylate, phenyl (meth) acrylate, benzyl (meth) acrylate, isobolonyl (meth) acrylate and the like.

Examples of the styrene-based monomer include styrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, α-methylstyrene, p-ethylstyrene, 2,4-dimethylstyrene, pn-butylstyrene, and p. -Tert-butyl styrene, pn-hexyl styrene, pn-octyl styrene, pn-nonyl styrene, pn-decyl styrene, pn-dodecyl styrene, p-phenyl styrene, 3,4- Examples thereof include styrene derivatives such as diclosylstyrene and vinyltoluene. Among these, particularly preferable styrene-based monomers include styrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, α-methylstyrene, p-ethylstyrene, 2,4-dimethylstyrene, and pn-. Butylstyrene, p-tert-butylstyrene, pn-hexylstyrene, pn-octylstyrene, pn-nonylstyrene, pn-decylstyrene, pn-dodecylstyrene, -phenylstyrene, 3 , 4-Diclosylstyrene, vinyltoluene and the like.

Examples of the ethylenically unsaturated nitrile include acrylonitrile and methacrylonitrile.
Examples of the vinyl ester include vinyl acetate and the like.
Examples of the epoxy group-containing vinyl monomer include glycidyl (meth) acrylate, methyl glycidyl (meth) acrylate, and allyl glycidyl ether. Among these, particularly preferable epoxy group-containing vinyl monomers are glycidyl (meth) acrylate and methyl glycidyl (meth) acrylate.

Examples of the ethylenically unsaturated basic vinyl monomer include dimethylaminoethyl (meth) acrylate and diethylaminoethyl (meth) acrylate.
Examples of the α, β-unsaturated vinyl monomer having an N-alkoxyalkyl-substituted amide group include N-methoxymethylacrylamide, N-methoxymethylmethacrylamide, N-ethoxymethylacrylamide, N-propoxymethylacrylamide, and N-butoxy. Examples thereof include methyl acrylamide.

Among the vinyl monomers, particularly preferable acrylic monomers include methyl (meth) acrylate, ethyl (meth) acrylate, n-butyl (meth) acrylate, t-butyl (meth) acrylate, and i-butyl (meth) acrylate. , N-octyl (meth) acrylate, lauryl (meth) acrylate, stearyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, isobornyl (meth) acrylate and other (meth) acrylic acid esters having hydrocarbon substituents, 2, Examples thereof include (meth) acrylic acid esters having a hydroxyalkyl group such as −hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, and 4-hydroxybutyl (meth) acrylate.

<Solvent>
The solvent used in the present invention is not particularly limited as long as it has little influence on the polymerization reaction at the polymerization temperature. Examples of the solvent include toluene, xylene, aromatic hydrocarbons such as "Ipsol (registered trademark) 150" (manufactured by Idemitsu Kosan Co., Ltd.) and "Ipsol 100" (manufactured by Idemitsu Kosan Co., Ltd.), methyl ethyl ketone, and methyl isobutyl. Examples include ketones, ketones such as 2-heptanone, ethyl acetate, ethyl-3-ethoxypropionate, esters such as n-butyl acetate, isopropanol, alcohols such as n-butanol and the like.

<Solution polymerization>
In solution polymerization for producing a vinyl-based polymer, the polymerization is started by starting the supply of the polymerization initiator and the vinyl monomer to the solvent. The polymerization initiator and the vinyl monomer may be supplied separately or may be mixed and supplied. The present invention includes a temperature raising step of polymerizing the vinyl monomer while raising the temperature of the solvent, and a temperature maintenance step of continuing the polymerization at a constant temperature after the temperature raising step. In both steps, the polymerization initiator and the vinyl monomer may be supplied to the reaction vessel by dropping from the upper part of the reaction vessel onto the solvent, or may be sent into the solvent solution through a pipe. Further, the supply rates of the polymerization initiator and the vinyl monomer may change during the polymerization period, and the supply may be intermittent. In the temperature maintenance step, it is preferable to continuously supply the polymerization initiator and the vinyl monomer at a constant rate.

Solution polymerization can be carried out using, for example, a polymerization apparatus provided with a stirrer, a thermometer, a condenser, a heating / cooling device, a supply tank, a supply pump, a reaction vessel and the like.

<Polymerization initiator>
The polymerization initiator used in the present invention is not particularly limited as long as it decomposes at the polymerization temperature to generate radicals. Examples of the polymerization initiator include 2,2-bis (4,5-di-t-butylperoxycyclohexyl) propane, t-butylperoxy2-ethylhexanoate, t-butylperoxylaurate, and t. -Butylperoxy 3,5,5-trimethylhexanoate, cyclohexanone peroxide, t-butylperoxyisopropyl carbonate, t-butylperoxyacetate, t-butylperoxybenzoate, t-hexylperoxy2-ethylhexa Noate, dicumyl peroxide, t-butyl cumyl peroxide, diisopropylbenzene hydroperoxide, di-t-butyl peroxide, di-t-amyl peroxide, di-t-hexyl peroxide, p-methane hydroper Organic peroxides such as oxide, cumene hydroperoxide, t-butyl hydroperoxide, azobisisobutylnitrile, azobisvaleronitrile, 2- (carbamoylazo) isobutyronitrile, 2,2-azobis (2,4) , 4-trimethylpentane), azo compounds such as 2-phenylazo-2,4-dimethyl-4-methoxyvaleronitrile, persulfates such as potassium persulfate, redox-based polymerization initiators and the like.

The polymerization initiator is preferably used in a ratio of 0.01 to 12 parts with respect to 100 parts of the vinyl monomer, more preferably 0.1 to 10 parts. As the amount of the polymerization initiator used increases, the molecular weight of the vinyl polymer tends to decrease, and the polymerization rate tends to increase. On the other hand, the smaller the amount of the polymerization initiator used, the more expensive the polymerization initiator can be used, which is industrially advantageous.

<heating process>
The temperature raising step is started by, for example, dropping the polymerization initiator and the vinyl monomer into a solvent heated to the polymerization start temperature in the reaction vessel and supplying the mixture by means such as in-liquid supply. After the start of polymerization, the heat generated by the polymerization is used to raise the temperature of the internal solution of the reaction vessel toward the target temperature while continuing the polymerization. The temperature raising process ends when the target temperature is reached. In this step, the polymerization initiator and the vinyl monomer may be supplied separately or may be mixed and supplied.

The amount of the vinyl monomer supplied in the temperature raising step is 10 to 40% by mass, preferably 15% by mass to 35% by mass, of the vinyl monomer used in the production. If the time of the temperature raising step is constant, the larger the supply amount, the larger the amount of heat generated by polymerization per unit time, so that the amount of heat supplied from the outside can be reduced until the target temperature is reached. Further, since the target temperature can be set higher by utilizing the heat generation of polymerization, it becomes easy to increase the polymerization rate with a small amount of polymerization initiator. The higher the polymerization temperature, the lower the molecular weight of the vinyl polymer obtained due to the chain transfer effect of the solvent. On the other hand, as the amount supplied in the temperature raising step is smaller, the molecular weight distribution of the polymer becomes narrower and the amount of the polymer having a high molecular weight decreases, so that the viscosity of the obtained polymer solution tends to decrease.

The polymerization start temperature is appropriately set in consideration of the decomposition rate of the polymerization initiator used. For example, when the polymerization initiator is dit-butyl peroxide or the like, the temperature is preferably 150 ° C to 200 ° C, more preferably 160 ° C to 180 ° C. The target temperature is preferably 180 ° C. to 230 ° C., more preferably 190 ° C. to 210 ° C. from the viewpoint of suppressing the formation of low molecular weight substances.

The average temperature rise rate in the temperature rise process (the value obtained by subtracting the temperature at the start of temperature rise from the target temperature of the internal liquid divided by the temperature rise time) is 0.3 ° C / min to 2.0 ° C / min. It is preferably 0.5 ° C./min to 1.5 ° C./min, more preferably. The average heating rate can be adjusted by the supply rate of the vinyl monomer, the heating / cooling device, and the like. The slower the speed, the easier the temperature control, which is preferable. Further, the higher the speed, the shorter the manufacturing time and the higher the productivity, which is preferable.

The time of the temperature raising step may be appropriately set in consideration of the dropping amount, the average temperature rising rate, and the like, but is generally 0.2 to 2 hours, more preferably 0.5 to 1 hour. The shorter this time is, the higher the productivity is, which is preferable.

<Temperature maintenance process>
The temperature maintenance step is a step of continuing the polymerization while maintaining the temperature of the inner liquid of the reaction vessel substantially constant after the temperature raising step is completed. In this step, in order to continue the reaction, the vinyl monomer as a raw material and the polymerization initiator are dropped and supplied to the reaction solution by means such as in-liquid supply. The polymerization initiator and the vinyl monomer may be supplied separately or may be mixed and supplied. The polymerization initiator and the vinyl monomer may be supplied intermittently, but it is preferable that the polymerization initiator and the vinyl monomer are continuously supplied to carry out the temperature maintenance step. The feed rate of the polymerization initiator and the vinyl monomer may change during the polymerization. In order to reduce the amount of unpolymerized vinyl monomer, for example, the supply of the vinyl monomer is stopped in the latter half of the process, and only the polymerization initiator is supplied to polymerize the unreacted vinyl monomer to increase the polymerization rate. You may increase it.

The temperature maintained in the temperature maintenance step is preferably 180 ° C. to 230 ° C., more preferably 190 ° C. to 210 ° C. from the viewpoint of suppressing the formation of low molecular weight substances. The supply amount of the vinyl monomer in this step is preferably 60 to 90% by mass, more preferably 65% by mass to 85% by mass of the vinyl monomer used in the production. The time of the temperature maintenance step may be appropriately set in consideration of the supply amount, the polymerization temperature, etc., but since the molecular weight distribution of the vinyl-based polymer to be produced is narrowed, 1 to 5 hours is preferable, and 1.5 to 4 is preferable. Time is more preferable.

<After temperature maintenance process>
After the temperature maintenance step, it is preferable to stop the supply of the vinyl monomer, lower the temperature of the internal solution, and then take out the internal solution (vinyl-based polymer solution) from the reaction vessel.

The present invention is characterized in that the polymerization is carried out while raising the temperature, and then the polymerization is continued at a constant temperature. Although the temperature can be raised by heating from the outside, it is advantageous to raise the temperature by utilizing part or all of the heat generated by the polymerization from the viewpoint of energy saving.

Here, "part" means "part by mass". For the polymerization reaction, a device consisting of a stirrer, a thermometer, a condenser, a heating / cooling device, a dropping tank, a dropping pump, and a 6 L reaction vessel equipped with a temperature control jacket was used.

The molecular weight of the vinyl polymer is determined by gel permeation chromatography manufactured by Toso Co., Ltd. on which a column "TSK-GEL SUPER HZM-N" manufactured by Toso Co., Ltd. is attached after preparing a tetrahydrofuran solution (0.6% by mass) of the vinyl-based polymer. Inject 10 μl of the prepared solution into a graphics (GPC) device, and use the average molecular weight in terms of standard polystyrene measured by the GPC method under the conditions of flow rate: 0.5 ml / min, eluent: tetrahydrofuran, column temperature: 40 ° C. is there. The Gardner viscosity (hereinafter referred to as viscosity) of the polymer solution was measured at 25 ° C. using a Gardner bubble viscometer manufactured by Fuji Rika Kogyo Co., Ltd.

[Example 1]
800 g of butyl acetate was charged into the reaction vessel as a solvent, and the temperature of the internal liquid in the reaction vessel was raised to 160 ° C., which is the polymerization initiation temperature, with the heat medium in the temperature control jacket. Then, it contains a monomer consisting of 1400 g of styrene, 1200 g of butyl acrylate, 1400 g of hydroxyethyl methacrylate, and 220 g of dit-butyl peroxide (manufactured by Nichiyu Co., Ltd., "Perbutyl (registered trademark) D") as a polymerization initiator. The mixed solution was dropped from the dropping tank into the internal solution using a dropping pump to initiate polymerization. Then, the internal solution was heated from 160 ° C. over 30 minutes to the target temperature of 190 ° C. at an average temperature rise rate of 1 ° C./min. After the temperature was raised, the monomer-containing mixed solution was added dropwise while maintaining 190 ° C., and the polymerization was continued for another 150 minutes. The entire amount of the monomer-containing mixed solution was added at a constant rate over 180 minutes from the start of dropping. After that, the temperature was maintained at 190 ° C. for 15 minutes and then cooled to room temperature to complete the production. The supply amounts of the vinyl monomers in the temperature raising step and the temperature maintaining step were 17% by mass and 83% by mass, respectively, of the total amount.

The weight average molecular weight of the vinyl polymer contained in the vinyl polymer solution thus obtained was 2900, and the number average molecular weight was 1600. The amount of unreacted vinyl monomer contained in the polymer solution was measured by gas chromatography and the polymerization rate was calculated to be 99%. The viscosity of the polymer solution was Z1Z2. The history of the internal liquid temperature and the jacket temperature measured from the start of dropping is as shown in FIG.

[Comparative Example 1]
Polymerization was initiated in the same procedure using the same manufacturing equipment as in Example 1. After that, the temperature was raised from 160 ° C. to 0.17 ° C./min, and the target temperature of 190 ° C. was reached over 180 minutes. The entire amount of the monomer-containing mixed solution was added at a constant rate over 180 minutes from the start of dropping. After that, the temperature was maintained at 190 ° C. for 15 minutes and cooled to complete the polymerization. The supply amounts of the vinyl monomers in the temperature raising step and the temperature maintaining step were 100% by mass and 0% by mass, respectively, of the total amount.

The weight average molecular weight of the vinyl polymer contained in the vinyl polymer solution thus obtained was 4100, and the number average molecular weight was 1900. The polymerization rate was 99%. The Gardner viscosity of the polymer solution was Z5. The history of the internal liquid temperature and the jacket temperature measured from the start of dropping is as shown in FIG.

[Comparative Example 2]
Using the same manufacturing apparatus as in Example 1, 800 g of butyl acetate was charged into the reaction vessel, and the temperature of the internal liquid in the reaction vessel was raised to the target temperature of 190 ° C. with the heat medium in the temperature control jacket. The heating rate between 160 ° C. and 190 ° C. was 1 ° C./min, and 30 minutes was required during this period. When the temperature reached 190 ° C., the same monomer-containing mixed solution as in Example 1 was started to be added dropwise to initiate polymerization. While maintaining the temperature of the internal solution at 190 ° C., the same amount of the monomer-containing mixed solution as in Example 1 was added at the same rate over 180 minutes at a constant rate. After that, the temperature was maintained at 190 ° C. for 15 minutes and then cooled to complete the polymerization.

The weight average molecular weight of the vinyl polymer contained in the vinyl polymer solution thus obtained was 2800, and the number average molecular weight was 1600. The polymerization rate was 99%. The Gardner viscosity of the polymer solution was Z1Z2. The history of the internal liquid temperature and the jacket temperature measured from the start of dropping is as shown in FIG.

In the method of Example 1, the time required for production is shorter than that of the conventional method in which the vinyl monomer is started to be supplied after the temperature rise and solution polymerization is carried out at a constant temperature as in Comparative Example 2, and the production is carried out through a jacket. Despite the small amount of heat supplied, a vinyl-based polymer having almost the same molecular weight and viscosity as in Comparative Example 2 was obtained. Further, the vinyl-based polymer solution obtained by the method of Example 1 has a lower viscosity than the conventional method of supplying a vinyl monomer only at the time of temperature rise and performing solution polymerization as in Comparative Example 1. It was easy to handle.

FIG. 1 is a graph showing the history of the internal liquid temperature and the jacket temperature measured from the start of dropping in Example 1. FIG. 2 is a graph showing the history of the internal liquid temperature and the jacket temperature measured from the start of dropping in Comparative Example 1. FIG. 3 is a graph showing the history of the internal liquid temperature and the jacket temperature measured from the start of dropping in Comparative Example 2.

Claims (2)

In a method for producing a vinyl polymer by a solution polymerization method in which a vinyl monomer is polymerized while being supplied to a solvent, a temperature raising step of polymerizing the vinyl monomer while raising the temperature of the solvent and a constant temperature after the temperature raising step are performed. A method for producing a vinyl-based polymer, which comprises a temperature maintenance step of continuing the polymerization in the above method, and the amount of the vinyl monomer supplied in the temperature raising step is 10 to 40% by mass of the vinyl monomer used in the production. The method for producing a vinyl polymer according to claim 1, wherein the average heating rate of the solvent in the temperature raising step is 0.3 ° C./min to 2.0 ° C./min.