JPS5922724B2 - Method of manufacturing syrup - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides continuous casting with a high polymer content that does not reduce the quality of the methyl methacrylate resin, maintains a suitable viscosity for good workability, and at the same time shortens board making time. The present invention relates to a method for producing syrup suitable for the continuous production of resin plates that undergo polymerization.

More specifically, the present invention relates to a method for producing syrup in which the cooling rate is controlled by using temperature-controlled monomers or syrup in the post-polymerization cooling treatment during syrup production. Syrup, which is a mixture of polymers and monomers, is generally produced by charging the monomer or monomer mixture into a polymerization vessel equipped with a reflux device, adding a polymerization initiator after raising the temperature, and maintaining the temperature at a constant temperature for a certain period of time. Manufactured by cooling.

The cooling process during syrup production is difficult due to the high viscosity of the single syrup, and in addition to this, the viscosity increases as polymerization progresses during cooling, so an external jacket attached to the polymerization vessel is required. If only the cooling means is used, the cooling rate is low and tends to lengthen the syrup production cycle. In particular, when producing a syrup with a high polymer content to shorten the polymerization time during continuous production of resin plates, the viscosity may increase abnormally, making handling difficult. Furthermore, the large difference in viscosity between batches of this type of syrup is a major drawback in stable casting and polymerization control during continuous production of resin plates. In order to increase the cooling rate of syrup and shorten the cooling time during syrup production, in addition to using an external cooling jacket attached to the polymerization vessel, a cooling pipe is installed inside the polymerization vessel to cool it from within. However, when manufacturing high-viscosity syrups, deposits occur around the cooling pipes, and this gradually increases, so it is not necessary to use internal cooling pipes. installation has the disadvantage of reducing the number of repeated uses of the polymerizer.

As a result of various studies on the above-mentioned problems, the inventors of the present invention have found that these problems can be solved by increasing the cooling rate by adding cold monomers and/or cold syrup to the cooling process during syrup production. Having learned that this is the case, he completed the present invention. That is, the present invention is a method for producing a resin plate by continuous casting and polymerization, which contains methyl methacrylate alone or at least one unsaturated vinyl compound that can be copolymerized with methyl methacrylate in a range of 20% by weight or less. When producing a syrup obtained by partially polymerizing a methyl methacrylate monomer mixture, the same type of cold monomer or/and cold syrup is added to the partially polymerized syrup. This is a method of producing syrup that consists of mixing and rapid cooling.

Generally, the polymer content in the syrup and the viscosity of the syrup are determined by the conditions during the syrup production.

For example, in order to obtain syrup with a high polymer content and low viscosity, it is produced by polymerizing under high temperature conditions using a large amount of polymerization initiator and then rapidly cooling the resulting syrup. However, in this case, the quenching treatment causes a small increase in the polymer content in the syrup, but the viscosity of the syrup increases significantly. This phenomenon becomes more pronounced when producing syrup with a high polymer content because the viscosity of the polymerized syrup is high, and the viscosity of the syrup increases due to insufficient cooling and the difference in viscosity between batches becomes even larger. have a tendency to In the methods conventionally used for this type of cooling method, the cooling rate normally decreases as the cooling time elapses, but this decrease in the cooling rate only increases the syrup viscosity during syrup production. This is therefore very disadvantageous for the production of syrups, which require as low a viscosity as possible with no difference between batches when the polymer content is the same. In the method of the present invention, when the syrup under high temperature conditions after polymerization is cooled to a predetermined temperature, the monomer and/or syrup whose temperature, amount, addition rate, etc. are adjusted are used to effectively carry out cooling at a high cooling rate. As a result, a low-viscosity syrup with little increase in viscosity can be obtained.

At the same time, the polymer content and viscosity of the product syrup can be simultaneously adjusted to compensate for differences between batches by keeping it constant or increasing or decreasing the amount of cooling monomer or syrup, polymer content, viscosity, etc. This makes it possible to stably maintain continuous production of resin plates.

The quenching method in the method of the present invention is generally carried out by adding and mixing cold monomers and/or cold syrup into the high temperature syrup (usually 95 to 110 DEG C.) after polymerization.

In this case, the method of adding and mixing high-temperature syrup in a polymerization vessel into a storage tank containing cold monomer or cold syrup takes a long time to transfer when a large volume is used, and tends to increase the viscosity of the syrup in the polymerization vessel. Therefore, usually the material is rapidly cooled to a predetermined temperature by adding a cold monomer or cold syrup, and then transferred to a storage tank containing the cold monomer or cold syrup, or it is rapidly cooled by adding a cold monomer or cold syrup. This method can be used effectively without any disadvantages by transferring the monomer or syrup to a storage tank containing cold monomer or syrup. The monomers added for cooling are preferably of a composition constituting the syrup to be cooled, and the temperature is adjusted before addition.

The syrup added for cooling is made by dissolving polymers such as methyl methacrylate polymer, methyl methacrylate-based copolymer, styrene polymer, and styrene-methyl methacrylate copolymer into monomers, or The polymer content can be obtained by preliminary production by partial polymerization of monomers, and the temperature can be adjusted as is before addition, or the polymer content can be adjusted by adding monomers and cooled, and the polymer content can be adjusted according to the purpose. arbitrarily selected by The amount of monomer or syrup added during cooling will vary depending on the temperature and degree of cooling required, but is usually from about 10 parts by weight to about 200 parts by weight per 100 parts by weight of syrup to be cooled. .

In this way, the syrup can be rapidly cooled to a temperature of 80°C or lower, preferably 60°C or lower. This rapid cooling should be done as quickly as possible, preferably within a few minutes. Once rapidly cooled to this temperature, a monomer or syrup may be further added and cooled, or cooling may be performed using a cooling jigget or the like. It should be noted that during quenching, if the amount of monomer or syrup added is too large, a large-capacity polymerization vessel will be required, which is not a good idea; if the amount is too small, the cooling effect will be small. The produced syrup is transferred to a storage tank that can hold an appropriate amount, and a portion of it is circulated and used as additional syrup for cooling. In the present invention, the method for continuously cast-polymerizing the syrup consisting of methyl methacrylate or a monomer and polymer containing methyl methacrylate as a main component is usually carried out by continuous cast-polymerization using a pair of upper and lower endless belts. Well-known continuous polymerization methods such as the method described above can be effectively employed as is.

The present invention will be described in more detail below with reference to Examples, but these Examples are merely illustrative and can be modified as appropriate within the scope of the configuration.

In addition, in the example? Unless otherwise specified, are all weights? shows. Example 1 40 kg of methyl methacrylate was charged into a polymerization vessel equipped with a reflux vessel, heated to 85°C, and then 289 g of azobis(2,4-dimethylvaleronitrile) was added.

Immediately, a temperature rise due to polymerization heat was observed, and the boiling point was reached after 2 minutes, and the jacket was kept at 100 to 102°C for 8 minutes.At the same time, 20 kg of methyl methacrylate at 20°C was added at the same time as jacket cooling was started, and the temperature rose to 78°C in 2 minutes. Rapid cooling followed by external cooling. The resulting syrup had a polymer content of 17.3% and a viscosity of 5.2 poise.

Note that the viscosity was measured at 25°C (the same applies below). Example
2 In place of methyl methacrylate at 20 °C in Example 1, 20 kg of syrup at 10 °C with a polymer content of 25.1%, which was obtained by dissolving Sumipet BMH (methacrylic resin molding material manufactured by Sumitomo Chemical) in methyl methacrylate monomer, was added. ,
It was rapidly cooled to 75° C. in 1 minute, followed by external cooling.

The resulting syrup had a polymer content of 25.2% and a viscosity of 23.
It was poise. Note that when cooling is performed only by jacket cooling without adding syrup, it takes 16.5 minutes to cool to 75°C, and the obtained syrup has a polymer content of 25.4% and a viscosity of 51. It was 2 points.

Example 3 40 kg of methyl methacrylate was charged into a polymerization vessel equipped with a reflux vessel, heated to 85°C, and azobis(
2,4 dimethylvaleronitrile) 28f! added.

Claims (1)

[Claims] 1. In a method of producing a resin plate by continuous casting and polymerization, a methyl methacrylate system containing methyl methacrylate alone or at least one unsaturated vinyl compound that can be copolymerized with methyl methacrylate in a range of 20% by weight or less When producing syrup by partially polymerizing a monomer mixture, the same type of cold monomer or/and cold syrup is mixed with the syrup obtained by partially polymerizing the monomer mixture. A method for producing syrup characterized by rapid cooling.