KR100272063B1 - Process for producing methacrylic polymer - Google Patents

Abstract

The methacrylic polymer is not colored, but the bulk or solution polymerization of the methacrylic monomer (a) to obtain a liquid polymer composition (b) containing an unreacted methacrylic monomer, containing an unreacted methacrylic monomer Prepared by separating the volatile component (c) to obtain a polymer (d), wherein the volatile component (c) containing the unreacted monomer is treated with a compound having a sulfonic acid group, followed by an amine compound, and recycled to the polymerization step. .

Description

Method for producing methacryl polymer

1 is a flow chart of one embodiment of the polymerization process according to the invention used in the examples,

2 is a flow chart of another embodiment of the polymerization process according to the invention.

The present invention relates to a method for producing a methacrylic polymer. Specifically, the present invention relates to a bulk polymerization method or a solution polymerization method for preparing a methacrylic polymer, including the step of recycling the unreacted methacrylic monomer as a raw material.

As a polymerization method of the methacrylic monomer, a batch suspension polymerization method using an aqueous medium is generally used. In recent years, there is no problem of wastewater treatment associated with aqueous media, so the use of bulk polymerization or solution polymerization is increasing, which is advantageous in terms of productivity and energy consumption.

For example, as for GB 1423288-A, GB 2005282-A, Japanese Tokhe Publication Nos. 49295/1989 and 26642/1990, and Japanese Patent Application Publication No. 111408/1991, various methods for bulk polymerization of methacrylic monomers can be made. There was a suggestion. The solution polymerization of methacrylic monomers is described in Japanese Patent Publication No. 7855/1980 and Japanese Patent Publication Nos. 132002/1983 and 57613/1988.

In the solution polymerization method or bulk polymerization method described above, the liquid polymer composition generally contains 30 to 80% by weight of the polymer and the unreacted methacrylic monomer. The methacrylic polymer is obtained by recovering the unreacted monomer from the reaction system and separating the unreacted monomer by evaporation. As such a hernia method, for example, a method using a vented extruder such as GB-1467045-A, Japanese Patent Publication No. 53682/1989 and Japanese Patent Publication Nos. 89710/1987 and 49925/1991 is known. .

Since the amount of unreacted monomer contained in the volatiles separated from the polymer composition by evaporation is very large relative to the amount of polymer, the unreacted monomer must be reused as raw material in industrial production. However, when the monomer is continuously reused, the resulting methacrylic polymer has a problem of deterioration of properties such as coloring of the polymer, reduction of weather resistance, and the like.

It is an object of the present invention to provide a method for producing a methacrylic polymer that can stably and efficiently produce a polymer with good quality even when polymerizing for a long time with continuous reuse of an unreacted polymer.

These and other objects will be apparent from the following description of the invention.

The present invention provides a liquid polymer composition (b) containing the unreacted methacrylic monomer by bulk or solution polymerization of the methacrylic monomer (a) and the volatile component (c) containing the unreacted monomer is separated to obtain a polymer ( In the method for producing a methacrylic polymer composed of obtaining d), a volatile component (c) containing an unreacted monomer is treated with a compound having a sulfonic acid group and then treated with an amine compound to be recycled to the polymerization step. It provides a method for producing a methacrylic polymer.

Methacrylic monomers are mixtures of methyl methacrylate or methyl methacrylate with at least one vinyl monomer copolymerizable therewith.

Methyl methacrylate can be prepared by conventional methods, for example by acetone-cyanohydrin method, by the catalytic oxidation of isobutylene or t-butanol to obtain methacrylic acid and esterification with methanol and the like. Can be.

Examples of other vinyl monomers include methacrylate esters (e.g. ethyl methacrylate, propyl methacrylate, butyl methacrylate, benzyl methacrylate, etc.), acrylate esters (e.g. methyl acrylate, ethyl acrylate, propyl) Acrylate, butyl acrylate, 2-ethylhexyl acrylate, etc.), unsaturated carboxylic acids (e.g. acrylic acid, methacrylic acid, maleic acid, itaconic acid, etc.), acid anhydrides (e.g. maleic anhydride, itaconic anhydride, etc.) , Monomers having hydroxyl groups (e.g. 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, monoglycerol acrylate, 2-hydroxyethyl methacrylate, hydroxypropyl methacrylate, monoglycerol meta Acrylates), nitrogen-containing monomers (e.g. acrylamide, methacrylamide, acrylonitrile, methacrylonitrile, diacetone Acrylamide, dimethylaminoethyl methacrylate, etc.), epoxy group-containing monomers (e.g. allyl glycidyl ether, glycidyl acrylate, glycidyl methacrylate, etc.), styrene monomers (e.g. styrene, α-methylstyrene Etc.).

The bulk polymerization process itself is known in the art and is described, for example, in GB 1423288-A, GB 2005282-A, Japanese Patent Publication Nos. 49295/1989 and 26642/1990 and Japanese Patent Publication No. 111408/1991. It is.

That is, any polymerization method may be used as long as the methacrylic monomer is polymerized and the liquid polymer composition containing the unreacted monomer is recovered.

In addition, the solution polymerization method itself is known in the art and is described, for example, in Japanese Patent Publication No. 7855/1980 and Japanese Patent Publication Nos. 132002/1983 and 57613/1988.

That is, any polymerization method can be used as long as the metaperyl monomer is polymerized in the presence of a solvent which is indiscriminate with respect to the polymerization and the liquid polymer composition containing the solvent and the unreacted monomer is recovered.

In the present invention, the term "volatile component" means a material containing an unreacted methacrylic monomer in the bulk polymerization method, and means a substance containing an unreacted methacrylic monomer in the solution polymerization method and an inert solvent (hereinafter, Volatile components).

Methods for separating volatile components from polymers in liquid polymer compositions are known, for example, from GB 1467045-A, Japanese Patent Publication No. 53682/1989 and Japanese Patent Publication Nos. 89710/1987 and 49925/1991. It can be performed by either.

That is, the liquid polymer composition is heated using a disc or screw vented extruder to evaporate the volatile components to separate the volatile components from the polymer.

The separated volatile components are treated with a compound having a sulfonic acid group followed by an amine compound by contact.

The above-mentioned contact treatment is preferably performed in the liquid phase after concentrating the volatile components, and may be performed in the gas phase.

Some or all of the volatile components are treated with compounds having sulfonic acid groups followed by continuous or intermittent treatment with amine compounds. Contact treatment of some or all of the volatile components, or continuous or intermittent contact treatment, depends on the properties of the polymer obtained, in particular on the color of the polymer, ie the degree of coloring. In order to facilitate the treatment, some of the volatile components are subjected to the above-mentioned contact treatment and the percentage of treated volatile components is adjusted by observing the degree of coloring of the polymer.

Since the volatile components may contain dimers or oligomers and / or chain transfer agents such as mercaptans used in the polymerization, the removal of them as heavy components by distillation before or after the contact treatment of the volatile components described above is recommended. desirable.

If water accumulates during the process, it can be separated from the volatile components by phase separation using the difference in specific gravity.

When distillation is performed before the contact treatment, the gaseous volatile components can be injected directly into the distillation apparatus.

Since polymerization of the unreacted monomer may proceed in the liquefied volatile component, it is preferable to add a polymerization inhibitor to the volatile component at an appropriate stage.

As a polymerization inhibitor, any conventional thing used for inhibiting superposition | polymerization of a methyl methacrylate monomer can be used. Examples of polymerization inhibitors include hydroquinone, hydroquinone monomethyl ether, phenothiazine, benzophenothiazine and the like. The polymerization inhibitor is generally used at a concentration of about 10 to 100 ppm by weight of the unreacted monomer.

As the compound having a sulfonic acid group used in the present invention, various solid or liquid compounds can be used. Examples of such compounds are sulfuric acid, benzenesulfonic acid, p-toluenesulfonic acid, dioctylsulfosuccinic acid, and strongly acidic cation exchange resins such as styrene-divinylbenzene copolymers having sulfonic acid groups as functional groups.

The amount of the compound having a sulfonic acid group is from 0.0001 to 0.01 equivalents of sulfonic acid group per mole of unreacted monomer.

Treatment time is generally about 10 to 120 minutes.

Treatment temperature is generally about 0-60 degreeC.

If the temperature is too low, the treatment efficiency decreases, while if too high, the monomers tend to hydrolyze.

Treatment conditions depend on the concentration of impurities and can be easily determined after some experiments.

The volatile components can be treated by mixing with a compound having a sulfonic acid group in a suitable vessel such as a stirring vessel. The volatile components are then separated from the mixture by conventional liquid-liquid separation methods such as phase separation, distillation, evaporation and the like.

In addition, if the compound having a sulfonic acid group is a solid compound such as an ion exchange resin and is insoluble in the volatile component, it is filled in the column and the volatile component is passed through the column. This method is preferred because the procedure is simple and the apparatus does not corrode or unreacted monomers are less hydrolyzed.

When the volatile components are treated using a packed column, they are generally passed through the column at a space velocity of about 0.1-10 hr ⁻¹ .

After contact with a compound having a sulfonic acid group, the volatile component is treated by contact with an amine compound.

In the present invention, the amine compound is amine and hydrazine.

As an amine compound, it is preferable that boiling point is higher than methyl methacrylate. More preferably, boiling point is 150 degreeC or more under atmospheric pressure.

As the amine compound, primary or secondary amines or hydrazines can be used. Examples of amine compounds include aliphatic amines (e.g. ethanolamine, hexamethylenediamine, octylamine, triethylenepentamine, tetraethylenepentamine, etc.), aromatic amines (e.g. aniline, phenylenediamine, etc.), hydrazine (e.g. hydrazine) , Phenylhydrazine, etc.).

In order to treat volatile components with amine compounds, any liquid-liquid mixing method can be used as long as they are in intimate contact.

For example, it is mixed in a vessel equipped with a stirrer or passed through a column with perforated plates or fills.

Generally, the treatment temperature is from room temperature to about 80 ° C. The treatment time is about 5 to 120 minutes.

The amount of the amine compound is generally from 0.0001 to 0.01 equivalents per mole of unreacted monomer.

Treated volatile components and amine compounds can be separated by liquid-liquid separation. In general, separation is achieved by distillation using a perforated plate column or packed column.

Distillation can be carried out to separate only the treated volatile components from the amines, while the dimer or oligomer and mercaptan can be removed together by distillation, or the untreated volatile components can be distilled together with the treated volatile components. Can be.

Treated volatile components containing unreacted material are mixed with fresh monomers and used in the polymerization step.

According to the present invention, methacrylic polymers with good color tone, which is one of the important properties of the polymer, can be prepared, even if they are of good quality, in particular unreacted monomers are continuously reused for a long time in the continuous bulk or solution polymerization of the polymer. .

The invention will be illustrated by the following examples which do not limit the scope of the invention.

The method used in the examples is shown in FIG. 1, where (1) represents a methacrylic monomer as a raw material, (2) represents a vinyl monomer as a raw material, (3) represents a chain transfer agent, (4) represents a polymerization initiator, (5) represents a polymer, (6) represents a waste liquid, (7) represents an amine compound, “a” represents a liquid polymer composition, and “b” represents a volatile component. And “c” represents the recovered monomer to be recycled.

The description of the main devices in the figures is as follows:

Monomer manufacturing container:

20ℓ, made of stainless steel SUS 304, with paddle type stirring vane, jacket type.

Catalyst dissolution vessel:

10ℓ, made of stainless steel SUS 304, with paddle type stirring vane, jacketed.

Polymerization Reactor:

10ℓ. Made of stainless steel SUS 304, with spiral ribbon stir blade, jacket type.

Burner:

Internal diameter 16.7 mm and length 3 mm, jacketed.

Vented Extruder:

Twin-screw extruder with a screw diameter of 30 mm, a cylinder length of 1200 mm and a different direction of rotation with one rear vent and three front vents (TEX-30, manufactured by Nippon Steel Works Co. Ltd)

Volatile Recovery Columns:

Internal diameter 100 mm, length 3 m, stainless steel SUS 304. It is filled with 3/8 inch Raschig rings made of stainless steel SUS 304, 0.7m long in the thickening section and 0.3m in the recovering section.

Ion Exchange Resin Columns:

3 L, made of stainless steel SUS 304, filled with 2 L of strongly acidic ion exchange resin with sulfonic acid group (Duolite C-26C, manufactured by Sumitomo Chemical Co., Ltd.).

Amine Treatment Container:

1 l, made of stainless steel SUS 304, equipped with paddle type stirring vanes, jacketed.

The properties of the obtained polymers were evaluated as follows:

(1) melt flow rate (MFR)

The melt flow rate is measured according to JIS K-7210 at 230 ° C. under a load of 3.8 kg using a melt flow index meter (manufactured by Takara Industries, Co., Ltd.).

(2) coloring degree

Using a 40 mm extruder with a T die (manufactured by Tanabe Plastics Co., Ltd.), the polymer is extruded at 250 ° C. and passed through a polishing roll maintained at about 100 ° C. to obtain a 3 mm thick plate.

From the extruded plate, a square plate sample (5 cm x 5 cm) was cut out and yellowness index (YI) using a spectrophotometer SZ-Σ80 (manufactured by Nippon Denshoku Industries Co., Ltd.) according to JIS K 7103. Measure

(3) weather resistance

The same plate samples used for colorimetry were irradiated with a sunshine weather meter (WE-SUN-HCA-1 type, manufactured by Suga Testing Machines, Co., Ltd.) at 63 ° C. for 2000 hours. The yellowness index (YI) is then measured and used as the degree of weather resistance.

Example 1

As raw materials and monomers, methyl methacrylate (hereinafter referred to as "MMA") (manufactured by Nippon Methacry1 Monomer Co., Ltd.) and methyl acrylate (hereinafter referred to as "MA") (manufactured by Toa Synthesis Co .. Ltd.) use. As the polymerization initiator, azobisisobutyronitrile (hereinafter referred to as "AIBN") is used, and n-octyl mercaptan (hereinafter referred to as "OM") is used as the chain transfer agent.

In the catalyst dissolution vessel, 6.2 wt% of MA and 0.12 wt% of AIBN with respect to MMA were added and mixed to completely dissolve AIBN in the monomer to prepare a catalyst solution.

By circulating the coolant in the jacket, the internal temperature in the catalyst dissolution vessel is maintained at 5 ° C.

The prepared catalyst solution is pumped continuously to the polymerization reactor at a rate of 1.47 kg / hour.

In the monomer preparation vessel, a monomer mixture containing 93.65 wt% MMA, 6.2 wt% MA and 0.15 wt% OM was prepared by adjusting the amount of fresh MMA, MA and OM fed, and the recycle amount and composition of the monomers recovered. Manufacture.

The internal temperature of the monomer production vessel is maintained at 5 ° C. by circulating the coolant in the jacket.

The prepared monomer mixture is pumped to the polymerization reactor at a rate of 13.279 kg / hr.

At the bottom of the polymerization reactor, the catalyst solution and monomer mixture described above are fed and polymerized with a residence time of 39 minutes at 150 ± 2 ° C. until the average degree of polymerization reaches 45% by weight. The resulting liquid polymer composition is removed from the top of the polymerization reactor and fed to the heater.

In the heater, the liquid polymer composition is heated to 200 ° C. or less by pressurizing the heating medium in the jacket and pressurized to 20 kg / cm ² G and then introduced into the vented extruder.

The liquid polymer composition is passed through an extruder while maintaining each vent and cylinder temperature at about 250 ° C. under reduced pressure, and the volatile components are recovered from the vent and fed to the volatile component recovery column.

The molten polymer is extruded in the form of strands. After cooling with water, the strands are cut to obtain pellets with an average production rate of 6.65 kg / hr.

The gaseous volatile components recovered from the rear vent of the extruder are supplied to the recovery portion of the volatile component recovery column, while the volatile components recovered from the front vent of the extruder are cooled and condensed to form a liquid, and then the volatile component recovery column To the bottom of the volatile component, where the volatile components are continuously distilled at reflux ratio 1.

An average of 7.98 kg / hr from the effluent recovered from the top of the volatile component recovery column is recycled to the monomer production vessel and fed to an ion exchange resin column followed by 1 kg / hr of distillate.

From the bottom of the volatile component recovery column, the waste liquid containing the amine used in the amine compound treatment step, the reaction product of the amine and the impurities is discharged at an average rate of 147 g / hr.

On top of the volatile component recovery column, hydroquinone (polymerization initiator) is continuously fed at a rate of about 0.5 g / hr.

The effluent from the volatile recovery column passes continuously to the ion exchange resin at an average rate of 1 kg / hr. At this stage the space velocity is about 0.5 hr ⁻¹ .

To the effluent from the ion exchange resin column, tetraethylenepentamide is continuously fed at a rate of 2 g / hr and the mixture is flowed into an amine compound treatment vessel. By heating the vessel with a jacket, the monomer and amine are sufficiently mixed in the vessel within an average residence time of about 1 hour while maintaining the internal temperature at 50 ° C.

The liquid flowing out of the amine compound treatment vessel is supplied to the bottom of the volatile component recovery column.

The continuous operation described above is continued for 30 days and the characteristics of the polymer samples obtained after 1 day, 20 days and 30 days are evaluated.

Melt flow rate of each polymer is 1.5, Y1 is 0.4, and weatherability is 0.7 in terms of YI.

Example 2

A polymer was prepared in the same manner as in Example 1, except that octylamine was supplied to the amine treatment container instead of tetraethylenepentamine.

The melt flow rate of each polymer is 1.5, Y1 is 0.4 and weatherability is 0.7 in terms of YI.

Example 3

The MA concentration in the catalyst dissolution vessel was adjusted to 10.5% by weight. The concentrations of MMA, MA and OM in the monomer production vessel were each 89.03% by weight. A polymer is prepared in the same manner as in Example 1, except that it is adjusted to 10.51 wt% and 0.46 wt%.

The melt flow rate of each polymer is 20, Y1 is 0.4 and weatherability is 0.7 in terms of YI.

The properties of the polymers are shown in the table.

Comparative Example 1

The polymer was prepared in the same manner as in Example 1 except that the entire effluent from the top of the volatile component recovery column was recycled directly to the monomer preparation vessel without further treatment.

Comparative Example 2

A polymer was prepared in the same manner as in Example 1 except that no amine compound was added to the effluent from the ion exchange resin column, that is, no amine treatment was performed.

The properties of the polymers are shown in the table.

Comparative Example 3

A polymer is prepared in the same manner as in Example 1, except that the effluent from the volatile component recovery column is directly supplied to the amine treatment vessel, that is, no treatment is performed in the ion exchange resin column.

The properties of the polymers are shown in the table.

[table]

Claims (5)

Bulk or solution polymerization of the methacrylic monomer (a) to obtain a liquid polymer composition (b) containing an unreacted methacrylic monomer, and the volatile component (c) containing an unreacted monomer is separated to give a polymer (d). A process for producing a methacryl-based polymer consisting of obtaining a volatile component (c), wherein the volatile component (c) containing an unreacted monomer is treated with a compound having a sulfonic acid group and then an amine compound to recycle to a polymerization step. . The process according to claim 1, wherein the volatile component (c) containing the unreacted monomer is distilled before treating with a compound having a sulfonic acid group. The process according to claim 1, wherein the volatile component (c) containing the unreacted monomer is treated with an amine compound and then distilled. The process according to claim 1, wherein the compound having a sulfonic acid group is a cation exchange resin having a sulfonic acid group. The process of claim 1 wherein the amine compound is a primary or secondary amine having a boiling point of at least 150 ° C. at ambient temperature.