JP2011042746A - Method for producing methacrylic-based viscous liquid - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a viscous liquid by a simple method without the blocking of a polymer in a liquid feed line at the bottom of a stirring tank. <P>SOLUTION: In the method for producing a methacrylic-based viscous liquid, a polymer including a methyl methacrylate unit and a monomer including methyl methacrylate are mixed together. When the polymer is dissolved in the monomer by being heated with stirring, gas is intermittently introduced from the liquid feed line. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a method for producing a viscous liquid by dissolving a methacrylic polymer.

  Polymethylmethacrylate used as an optical polymer has features such as ease of processing, ease of handling, light weight, and low cost, as well as high transparency and low birefringence. It is used for various optical applications such as optical films for displays, and a polymer having a high polymethyl methacrylate content is required from the viewpoint of various optical properties.

  However, methyl methacrylate, which is a monomer of polymethyl methacrylate, is generally known to have a low polymerization rate. Therefore, it is necessary to shorten the time required for the polymerization in a production method utilizing polymerization such as a cell casting method for sheet production.

  As a method for improving the polymerization rate, there is a method of using a syrup prepared by raising the temperature of a methyl methacrylate monomer, adding a polymerization initiator, polymerizing a part of the monomer and then cooling it (Patent Document 1). If an attempt is made to increase the concentration of polymethyl methacrylate in the syrup by this method, the viscosity of the syrup also increases, and the polymerization rate increases rapidly, so that it is difficult to cool and stop the polymerization at a desired polymer concentration. . Therefore, a method of preparing syrup by dissolving polymethyl methacrylate that has been polymerized in advance in a methyl methacrylate monomer can be mentioned.

  However, in the case of this method, if polymethyl methacrylate is to be dissolved in methacrylate in a stirring tank having a liquid feed line for transferring syrup to the next step, the solubility of polymethyl methacrylate is not high. Since the specific gravity of polymethyl methacrylate is larger than that of methyl methacrylate, polymethyl methacrylate may settle in the lower liquid feed line, and the polymers may adhere to each other in the line to block the line.

JP 49-99185 A

  The object of the present invention is to prevent the polymer from being blocked by the above-mentioned line by a simple method when dissolving the polymer and the monomer by heating with stirring in a preparation tank having a liquid feeding line at the bottom. is there.

  The present invention is a method for producing a methacrylic viscous liquid by mixing a polymer containing methyl methacrylate units and a monomer containing methyl methacrylate, and stirring the polymer and the monomer in a stirring tank having a liquid feed line at the bottom. In the method for producing a methacrylic viscous liquid, the gas is intermittently introduced from the liquid feeding line when dissolved by heating.

  According to the present invention, it is possible to produce a viscous liquid by dissolving the polymer and the monomer while stirring, without blocking the polymer in the liquid feeding line at the bottom of the stirring tank, by a simple method without major equipment change. .

FIG. 1 is a schematic configuration diagram showing an example of equipment for carrying out the present invention.

  The present invention is a method for producing a methacrylic viscous liquid. The viscous liquid is made from a polymer containing methyl methacrylate (hereinafter referred to as “MMA”) units and a monomer containing MMA as raw materials. The present invention is characterized in that, in a stirring tank having a liquid feeding line at the lower part, when the polymer and the monomer are dissolved by heating while stirring, gas is intermittently introduced from the liquid feeding line.

  The polymer containing the MMA unit as the raw material of the present invention is obtained by polymerizing a monomer raw material consisting of MMA alone or a mixture of MMA and a vinyl monomer copolymerizable therewith. The polymerization method of the polymer is not particularly limited, and examples thereof include known methods such as suspension polymerization, emulsion polymerization, solution polymerization, and bulk polymerization. The polymer containing MMA units is preferably in the form of powder or granules from the viewpoint of ease of dissolution, and the particle size thereof is preferably 10 mm or less from the viewpoint of ease of dissolution. More preferably, it is 3 mm or less.

  The monomer containing MMA which is a raw material of the present invention is not particularly limited as long as it dissolves a polymer containing MMA units. Examples of monomers other than MMA include methacrylic acid esters other than MMA such as ethyl methacrylate, isopropyl methacrylate, butyl methacrylate, 2-ethylhexyl methacrylate, phenyl methacrylate, and benzyl methacrylate, methyl acrylate, ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, and the like. Acrylic acid esters, acrylic acid, methacrylic acid, maleic acid, itaconic acid and other unsaturated carboxylic acids, maleic anhydride, itaconic anhydride and other acid anhydrides, N-phenylmaleimide, N-cyclohexylmaleimide, Nt- Maleimide derivatives such as butylmaleimide, hydrides such as 2-hydroxypropyl acrylate, 2-hydroxyethyl acrylate and 2-hydroxypropyl methacrylate Xylene group-containing monomers, (meth) acrylamide, (meth) acrylonitrile, diacetone acrylamide, nitrogen-containing monomers such as dimethylaminoethyl methacrylate, epoxy group-containing monomers such as allyl glycidyl ether, glycidyl acrylate, and glycidyl methacrylate Styrene monomers such as styrene and α-methylstyrene, cross-linking agents such as ethylene glycol diacrylate, allyl acrylate, ethylene glycol dimethacrylate, allyl methacrylate, divinylbenzene, trimethylolpropane triacrylate, and the like. One or more types are selected and used. Here, “(meth) acryl” means “methacryl” or “acryl”.

  In addition to the above monomers, non-polymerizable solvents, for example, aromatic compounds such as toluene, ethylbenzene, o-xylene, m-xylene and p-xylene, aliphatic compounds such as octane, decane and cyclohexane, esters such as butyl acetate and pentyl acetate You may add compounds, alcohols, such as methanol and ethanol.

  A viscous liquid obtained by mixing a polymer containing MMA units and a monomer containing MMA contains 90% by mass or more of MMA units and MMA from the viewpoint of securing the original physical properties of a methacrylic resin obtained by polymerizing the same. Is preferred.

  From the viewpoint of handling of the viscous liquid and the physical properties of the methacrylic resin obtained by polymerization, the polymer preferably has a weight average molecular weight of 30,000 to 500,000. From the same viewpoint, the content of the polymer in the viscous liquid is preferably 30 to 60% by mass.

  In order to polymerize a viscous liquid in a post process, it is preferable to add a polymerization initiator to this. As the polymerization initiator, known polymerization initiators such as a photopolymerization initiator and a thermal polymerization initiator can be used.

  Although the example of the equipment used by this invention is shown in FIG. 1, this invention is not limited to this.

  A methacrylic viscous liquid is produced in the stirring tank 1. The stirring tank 1 has a stirrer 2 and a hot water jacket 4. The stirrer includes a motor, a rotating shaft, and a stirring blade. The shape of the stirring blade is not particularly limited, and examples thereof include a paddle blade, a ribbon blade, a helical blade, a propeller blade, and a turbine blade. The jacket wraps around the outer surface of the stirring tank, and the temperature in the stirring tank is adjusted by flowing a heat transfer medium through the jacket.

  A raw material charging hopper 3 and a liquid feeding line 5 are connected to the stirring tank 1. The raw material charging hopper 3 supplies a polymer containing MMA units as raw materials and a monomer containing MMA into the stirring tank, and this raw material charging hopper has a void at the upper part of the stirring tank (the raw material liquid is not soaked). It is preferable to be connected to a location. Instead of the raw material charging hopper 3, a raw material supply line may be provided to continuously supply the raw materials. The liquid feed line 5 is a pipe for transferring the obtained viscous liquid to the next process. The liquid feeding line 5 is connected to the lower part of the stirring tank. From the viewpoint of smooth liquid feeding, the liquid feeding line 5 is preferably connected to the bottom surface of the stirring tank. A gas introduction line 8 is connected to the liquid feeding line 5, and gas is introduced from here.

  The methacrylic viscous liquid of the present invention can be obtained by the following procedure. After the bottom valve 6, the liquid feed line valve 7, and the gas introduction line valve 9 shown in FIG. 1 are closed, the raw material is charged from the raw material charging hopper 3 and the stirrer 2 is operated. The pressure of the gas introduced by the pressure adjustment valve 10 is adjusted to a desired pressure, and the gas introduction line valve 9 is opened. Hot water is supplied to the hot water jacket 4 from a pipe (not shown) and heated, and the bottom valve 6 is opened and closed intermittently to introduce gas intermittently from the liquid feed line 5 into the stirring tank. Thereby, the polymer which settles and accumulates on the bottom face (the bottom face valve 6 upper part) of a stirring tank can be removed, and it can prevent that the said location block | closes.

  Examples of the method of intermittently opening and closing the bottom valve 6 include a method of intermittently opening and closing manually, and a method of automatically opening and closing intermittently using an electromagnetic valve or the like.

  The pressure when introducing the gas is preferably 20 kPa or more, and more preferably 50 kPa or more. The pressure is preferably 500 kPa or less, and more preferably 250 kPa or less. If the pressure is too low, the polymer that has settled in the liquid feed line cannot be removed, and if the pressure is too high, the polymer will scatter and enter the void of the stirring tank (the upper inner wall where the raw material liquid is not immersed). Adhere to.

  When gas is intermittently introduced into the stirring tank from the liquid feeding line, it is preferably introduced at intervals of 10 to 120 seconds, more preferably at intervals of 20 to 60 seconds. . When this interval is too short, the monomer tends to volatilize, the flow in the stirring tank is disturbed, and the stirring tends to be uneven. On the other hand, if the interval is too long, the polymer tends to adhere to the liquid feed line and the polymers tend to adhere to each other. One gas introduction time is preferably 2 seconds or less from the viewpoint of suppressing the amount of gas used and reducing the volatilization amount of the monomer. In addition, air, nitrogen, etc. can be used as a kind of gas. The shape of the gas outlet is not particularly limited.

  In the present invention, the polymer is dissolved by heating while stirring the polymer and the monomer with a stirrer. Heating can be performed by passing warm water through the jacket of the stirring tank. The temperature at the time of melting by heating is preferably 50 ° C. or higher, and more preferably 60 ° C. or higher. The temperature is preferably 90 ° C. or lower, and more preferably 80 ° C. or lower. If the temperature is too low, the polymer is difficult to dissolve and the dissolution time tends to be long. If the temperature is too high, the monomer tends to boil and volatilize easily.

  After obtaining the viscous liquid of the present invention, if necessary, a polymerization inhibitor for preventing coloring and spontaneous curing, a chain transfer agent for adjusting the molecular weight, a stabilizer such as an antioxidant and an ultraviolet absorber, Various known additives such as a flame retardant, a release agent, a dye and a pigment may be added.

  The viscous liquid obtained by the present invention can be used for various applications as syrup. For example, a polymerization initiator can be added to the syrup and cured in a mold to obtain a desired molded product such as a resin plate.

Hereinafter, the present invention will be specifically described by way of examples.
Example 1
A methyl methacrylate polymer (hereinafter referred to as “PMMA”) was prepared by dissolving 30 g of UV-degradable polymerization initiator 1-hydroxy-cyclohexyl-phenyl ketone (Ciba Specialty Chemicals, Irgacure 184) in 1.8 kg of methyl methacrylate monomer. .) 1.2 kg of beads (manufactured by Mitsubishi Rayon Co., Ltd., BR-83, particle size of about 0.1 mm) was placed in a stirring tank having a hot water jacket. The stirring tank has a diameter of 160 mm, a depth of 300 mm, and a feed line of 1/2 inch (12.7 mm) at the bottom of the kettle. As a stirring blade, a ribbon blade having a diameter of 130 mm and a height of 170 mm is stirred at a position of 10 mm from the bottom of the stirring tank. The blade was attached so that the tip of the blade came, and was rotated at a stirring speed of 120 revolutions per minute. After flowing 60 ° C warm water through the warm water jacket of the agitation tank, stir and mix for 1 second every 15 seconds while introducing air at a pressure of 50 kPa from the liquid feed line on the bottom surface, and warm water is passed for 30 minutes. Thus, the polymer beads were dissolved to produce a viscous liquid.

By introducing air from the bottom surface, the beads could be uniformly dissolved without sedimentation and accumulation, and the subsequent removal of the viscous liquid from the bottom surface was no problem.
(Example 2)
1.5 kg of methyl methacrylate monomer, 60 g of 1-hydroxy-cyclohexyl-phenyl ketone, 1.5 kg of PMMA beads, and the same stirring tank as in Example 1, with a hot water temperature of 85 ° C., every 60 seconds, for 1 second. A viscous liquid was produced in the same manner as in Example 1 except that air was introduced at a pressure of 300 kPa from the liquid feeding line on the bottom.

Again, there was no sedimentation or accumulation of beads, and they could be dissolved uniformly.
(Example 3)
It is changed to a stirring tank having a diameter of 400 mm and a depth of 900 mm, and having a warm water jacket, in which 17.5 kg of methyl methacrylate monomer and 125 g of a UV-decomposable polymerization initiator 1-hydroxy-cyclohexyl-phenyl ketone are dissolved, PMMA 7.5 kg of beads were added. As a stirring blade, a blade with a diameter of 250 mm, a width of 50 mm, four blades, and a 45 ° inclined paddle blade provided in two stages at a position of 60 mm and 160 mm from the bottom of the stirring tank, the stirring speed was 150 rpm. Rotated. After flowing warm water of 70 ° C through the warm water jacket of the stirring tank, stirring and mixing are performed while introducing air at a pressure of 150 kPa from the 1-inch (25.4 mm) feed line on the bottom surface every 30 seconds for 1 second. The polymer beads were dissolved by passing warm water for 40 minutes to produce a viscous liquid.

Even if the amount of the raw material was increased by changing the stirring tank, the beads were not settled and deposited, and could be dissolved uniformly.
Example 4
24 kg of methyl methacrylate monomer, 120 g of 1-hydroxy-cyclohexyl-phenyl ketone, and 16 kg of PMMA beads, air in the same stirring tank as in Example 3 at a hot water temperature of 80 ° C. and a pressure of 200 kPa from the feed line at the bottom of the kettle A viscous liquid was produced in the same manner as in Example 3 except that was introduced.

Again, there was no sedimentation or accumulation of beads, and they could be dissolved uniformly.
(Example 5)
Changed to PMMA (Mitsubishi Rayon Co., Ltd., ACRYPET VH001, particle size of about 3 mm), and introduced air at a pressure of 100 kPa from the bottom of the stirring tank for 1 second every 60 seconds, and the hot water flow time was 120 minutes A viscous liquid was produced in the same manner as in Example 1 except that.

Even if the particle size of the polymer changed, it could be dissolved uniformly without sedimentation or deposition.
(Comparative Example 1)
A viscous liquid was produced in the same manner as in Example 1 except that air was not introduced from the bottom of the stirring tank. Since air was not introduced from the bottom surface, the polymer beads settled and deposited on the liquid feed line in the middle of dissolution, and the liquid feed line was blocked by dissolving and fixing only the surface in the line. . For this reason, the viscous liquid produced in the tank cannot be taken out by the liquid feeding line on the bottom surface.
(Comparative Example 2)
A viscous liquid was produced in the same manner as in Example 1 except that air was continuously introduced from the bottom of the stirring tank at a pressure of 50 kPa.

Since air was constantly introduced from the bottom surface, the polymer did not settle or accumulate on the liquid feed line, and the produced viscous liquid could be taken out. However, the air flow from the bottom surface became uneven in the stirring tank, and the donut-shaped polymer insoluble matter adhered to the periphery of the liquid feeding line on the bottom surface.
(Example 6)
A viscous liquid was produced in the same manner as in Example 3, except that air was introduced at a pressure of 600 kPa from the liquid feeding line on the bottom of the stirring tank. Since the gas was intermittently introduced, there was no clogging of the liquid feeding line on the bottom surface, but since the air introduction pressure was too high, a part of the undissolved polymer powder was scattered on the top surface and side wall of the stirring tank. As a result, it was fixed.
(Example 7)
A viscous liquid was produced in the same manner as in Example 4 except that air was introduced at a pressure of 10 kPa from the liquid feeding line on the bottom of the stirring tank. Since the gas introduction pressure is low, it is not possible to return all of the polymer that has settled and accumulated in the liquid supply line back into the tank, and in some parts of the liquid supply line, the polymer is fixed and undissolved polymer is confirmed when the viscous liquid is taken out. It was. Although air was introduced even though the pressure was low, there was no complete blockage of the liquid feeding line, but due to partial blockage, it took time to feed the liquid.

  The production conditions of Examples 1 to 7 and Comparative Examples 1 to 4 are summarized in Tables 1 and 2.

  The present invention can be widely applied as a method for producing a methacrylic viscous liquid.

DESCRIPTION OF SYMBOLS 1 Decomposition tank 2 Stirrer 3 Raw material charging hopper 4 Hot water jacket 5 Liquid feed line 6 Bottom valve 7 Liquid feed line valve 8 Gas introduction line 9 Gas introduction line valve 10 Pressure control valve

Claims (6)

  A method for producing a methacrylic viscous liquid by mixing a polymer containing a methyl methacrylate unit and a monomer containing methyl methacrylate, and heating the polymer and the monomer while stirring them in a stirring tank having a liquid feed line at the bottom. When melt | dissolving by this, the manufacturing method of the methacrylic viscous liquid which introduce | transduces gas intermittently from the said liquid feeding line.   The method for producing a methacrylic viscous liquid according to claim 1, wherein the pressure when introducing the gas is 20 kPa or more and 500 kPa or less.   The method for producing a methacrylic viscous liquid according to claim 1 or 2, wherein the polymer to be dissolved is powdery or granular, and the particle size thereof is 0.1 mm or more and 10 mm or less.   The method for producing a methacrylic viscous liquid according to Claims 1 to 3, wherein the gas introduction time from the lower part of the stirring tank is set to 2 seconds or less and is introduced at intervals of 10 seconds to 120 seconds.   The method for producing a methacrylic viscous liquid according to claims 1 to 4, wherein the temperature when heated and dissolved is 50C or higher and 95C or lower.   The method for producing a methacrylic viscous liquid according to claim 1, wherein the viscous liquid contains a photopolymerization initiator.

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