JP2022102342A - Pipe inside cleaning method for cleaning high viscosity resin solution in pipe - Google Patents

Abstract

To provide a cleaning method capable of improving working efficiency for cleaning a pipe having no driving part and a static mixer, in a production process of high viscosity resin solution.SOLUTION: A pipe inside cleaning method for cleaning high viscosity resin solution filling the inside of a pipe includes setting viscosity of the high viscosity resin solution at 1,200-4,000 poise, diluting the high viscosity resin solution with a solvent, feeding the same kind of resin solution having low viscosity and substituting the inside of the pipe, substituting the inside of the pipe with the same kind of resin solution having lower viscosity than that of the resin solution a plurality of times, and finally cleaning the inside of the pipe with an organic solvent.SELECTED DRAWING: None

Description

The present invention relates to a method for cleaning a high-viscosity resin solution in a pipe.

When a resin composition such as a liquid resin or a resin solution has a high viscosity and low miscibility with a solvent, the resin composition adhering to the wall surface cannot be removed unless a large amount of solvent is flowed at a high flow rate, resulting in a large amount of waste. There was a problem such as occurring. After the solvent is once circulated, it can be easily removed by mixing the resin composition and the solvent by allowing it to stand still to reduce the viscosity, but in this case, there is a problem that the work efficiency is lowered.

In order to solve the above problem, a circulation line for cleaning may be laid separately, but the device configuration may be complicated or a large amount of cleaning solution may be required.
Further, in the case of a kneading device having a drive unit such as a screw, there is a method of separately preparing resin compositions having different viscosities and cleaning them in sequence, but the resin composition and the subsequent resin composition to be a product remain in the device. It may be mixed with the cleaning resin composition to cause deterioration of the quality of the product resin composition. (Patent Document 1)

JP-A-2018-42219

In the process of producing a high-viscosity resin solution, since the viscosity difference between the high-viscosity resin solution and the solvent is large, the resin composition adhering to the wall surface cannot be removed unless a large amount of solvent is flowed at a high flow rate. There is a similar problem, and especially when a static mixer is installed during the process, there is a problem that cleaning is particularly difficult because the elements inside the static mixer are not driven.

An object of the present invention is to provide a cleaning method for improving work efficiency for cleaning a pipe or a static mixer having no drive unit inside a flow path in a process for producing a high-viscosity resin solution.

The present inventors have completed the present invention as a result of diligent studies for solving the above-mentioned problems. That is, the present invention has the following configuration.

[1]. It is an in-pipe cleaning method for cleaning the high-viscosity resin solution filled in the pipe, and the viscosity of the high-viscosity resin solution is 1200 to 4000 poise, and the same type of resin solution having a lower viscosity than the high-viscosity resin solution can be used. A method of cleaning the inside of a pipe by sending a liquid to replace the inside of the pipe, replacing the inside of the pipe with a resin solution of the same type having a lower viscosity than the resin solution of the previous term, and finally cleaning with an organic solvent.

[2]. The in-pipe cleaning method according to [1], wherein the low-viscosity resin solution is prepared by diluting the high-viscosity resin solution with an organic solvent.

[3]. The in-pipe cleaning method according to [1] or [2], wherein the low-viscosity resin solution is prepared using a batch-type mixing tank.

[4]. The in-pipe cleaning method according to any one of [1] to [3], wherein the resin solution is a polyamic acid solution.

[5]. The method for cleaning an inside of a tube according to any one of [1] to [4], wherein the tube is a static mixer.

In the present invention, in the process of manufacturing a high-viscosity resin solution, it is possible to improve work efficiency for cleaning pipes without a drive unit and a static mixer.

It is a figure which shows the polyamic acid production system.

When the resin composition such as a liquid resin or a resin solution has a high viscosity and low miscibility with a solvent, the present invention can be suitably applied, and a method for cleaning the inside of a pipe in a polyamic acid production system will be described as a specific example. The present invention is not limited to this.

The system is a polyamic acid production system including a reaction unit for polymerizing a polyamic acid and a mixer unit for stirring a polymerization solution in which the polyamic acid is dissolved, and the desired polyamic acid produced by the polyamic acid production system is highly produced. In the case of a viscous polymerization solution, a solvent is added to the high-viscosity polymerization solution produced in the reaction section to reduce the viscosity of the polymerization solution to obtain a low-viscosity polymerization solution, and the high-viscosity polymerization solution inside the pipe and mixer has low viscosity. It is an in-tube cleaning method characterized by substituting with a polymerization solution.

The system has a reaction section for polymerizing polyamic acid and a mixer section for stirring the polymerization solution in which the polyamic acid is dissolved. However, even if the mixer section is a pipe without a stirring function, it is manufactured by the polyamic acid production system. When the desired polyamic acid is used as a high-viscosity polymerization solution, a solvent is added to the high-viscosity polymerization solution produced in the reaction section to reduce the viscosity of the polymerization solution to obtain a low-viscosity polymerization solution, and the high-viscosity polymerization inside the pipe. The solution can be replaced with a low viscosity polymerization solution.

The outline of the polyamic acid production system will be described with reference to FIG. The polyamic acid production system produces a polyamic acid from a first solution A1 in which a polyadditive first polymerizable compound is dissolved and a polyadditive second polymerizable compound that is polyadditive with the first polymerizable compound. It is a system.

Hereinafter, as an example, a case where one of the first polymerizable compound and the second polymerizable compound is tetracarboxylic acid dianhydride and the other is a diamine will be described. More specifically, a case where the first polymerizable compound is a tetracarboxylic acid dianhydride and the second polymerizable compound is a diamine will be described.

The tetracarboxylic acid dianhydride is not particularly limited, and the same ones used in conventional polyimide synthesis can be used. Specific examples of the tetracarboxylic acid dianhydride include 3,3', 4,4'-benzophenone tetracarboxylic acid dianhydride, 3,3', 4,4'-biphenyltetracarboxylic acid dianhydride, 2, 3,3', 4'-biphenyltetracarboxylic acid dianhydride, pyromellitic acid dianhydride, 1,3-bis (2,3-dicarboxyphenoxy) benzene dianhydride, 1,4-bis (2) 3-Dicarboxyphenoxy) benzene dianhydride, 2,3,3', 4'-benzophenone tetracarboxylic acid dianhydride, 2,2', 3,3'-benzophenone tetracarboxylic acid dianhydride, 2,2 ', 3,3'-biphenyltetracarboxylic acid dianhydride, 2,2', 6,6'-biphenyltetracarboxylic acid dianhydride, naphthalene-1,2,4,5-tetracarboxylic acid dianhydride, Anthracene-2,3,6,7-tetracarboxylic acid dianhydride, phenanthrene-1,8,9,10-tetracarboxylic acid dianhydride, 2,2-bis (4-hydroxyphenyl) propandibenzoate-3 , 3', 4,4'-Aromatic tetracarboxylic acid dianhydride such as tetracarboxylic acid dianhydride; aliphatic tetracarboxylic acid such as butane-1,2,3,4-tetracarboxylic acid dianhydride; Dinohydrate; alicyclic tetracarboxylic acid dianhydride such as cyclobutane-1,2,3,4-tetracarboxylic acid dianhydride; thiophene-2,3,4,5-tetracarboxylic acid dianhydride, pyridine -Heterocyclic tetracarboxylic acid dianhydride such as 2,3,5,6-tetracarboxylic acid dianhydride; and the like. The tetracarboxylic acid dianhydride may be used alone or in combination of two or more.

As the solvent of the first polymerizable substance, a solvent in which tetracarboxylic acid dianhydride and polyamic acid are dissolved is used. Specific examples of the solvent include amide-based solvents such as N, N-dimethylformamide, N, N-dimethylacetamide, N-methyl-2-pyrrolidone, 1,3-dimethyl-2-imidazolidinone, and acetoanilide; γ- Cyclic ester solvents such as butyrolactone; Chain ester solvents such as ethyl acetate; Ketone solvents such as 2-propanone, 3-pentanone, acetone, and methyl ethyl ketone; Ether solvents such as tetrahydrofuran and dioxolan; Methanol, ethanol, isopropanol and the like. Alcohol-based solvent; aromatic hydrocarbon-based solvent such as toluene and xylene; and the like. Among these, amide-based solvents, cyclic ester-based solvents, and ether-based solvents, which have high solubility of polyamic acids, are preferable. As the solvent, one type may be used alone, or two or more types may be mixed. For example, improving the solubility of polyamic acid by mixing a highly polar alcohol solvent with a solvent having relatively low solubility of polyamic acid such as acetone, ethyl acetate, methyl ethyl ketone, toluene, and xylene. Is also possible.

The first solution A1 may contain a small amount of a tertiary amine such as trimethylamine or triethylamine in order to enhance the solubility of the tetracarboxylic acid dianhydride or the reactivity with the diamine.
The diamine is not particularly limited, and the same diamines used in conventional polyimide synthesis can be used. Specific examples of the diamine include 4,4'-diaminodiphenylmethane, 4,4'-diaminodiphenyl ether, 2,2-bis [4- (4-aminophenoxy) phenyl] propane, and 4,4'-bis (4-). Aminophenoxy) Biphenyl, 1,4'-bis (4-aminophenoxy) benzene, 1,3'-bis (4-aminophenoxy) benzene, o-phenylenediamine, m-phenylenediamine, p-phenylenediamine, 3, 4'-diaminodiphenyl ether, 4,4'-diaminodiphenyl sulphon, 3,4'-diaminodiphenyl sulphon, 3,3'-diaminodiphenyl sulphon, 4,4'-methylene-bis (2-chloroaniline), 3, 3'-dimethyl-4,4'-diaminobiphenyl, 4,4'-diaminodiphenylsulfide, 2,6-diaminotoluene, 2,4-diaminochlorobenzene, 1,2-diaminoanthraquinone, 1,4-diaminoanthraquinone, Aromatic diamines such as 3,3'-diaminobenzophenone, 3,4'-diaminobenzophenone, 4,4'-diaminobenzophenone, 4,4'-diaminobibenzyl; 1,2-diaminoethane, 1,4-diamino Aliphatic diamines such as butane, tetramethylenediamine and 1,10-diaminododecane; 1,4-diaminocyclohexane, 1,2-diaminocyclohexane, bis (4-aminocyclohexyl) methane, 4,4'-diaminodicyclohexylmethane and the like. Alicyclic diamines; heterocyclic diamines such as 3,4-diaminopyridine; and the like. One type of diamine may be used alone, or two or more types may be used in combination.

The diamine may be added as a solid, or may be added as a solution using a solvent. As the solvent, a solvent in which diamine and polyamic acid are dissolved is used. Specific examples of the solvent include amide-based solvents such as N, N-dimethylformamide, N, N-dimethylacetamide, N-methyl-2-pyrrolidone, 1,3-dimethyl-2-imidazolidinone, and acetoanilide; γ- Cyclic ester solvents such as butyrolactone; Chain ester solvents such as ethyl acetate; Ketone solvents such as 2-propanone, 3-pentanone, acetone, and methyl ethyl ketone; Ether solvents such as tetrahydrofuran and dioxolan; Methanol, ethanol, isopropanol and the like. Alcohol-based solvent; aromatic hydrocarbon-based solvent such as toluene and xylene; and the like. Among these, amide-based solvents, cyclic ester-based solvents, and ether-based solvents, which have high solubility of polyamic acids, are preferable. As the solvent, one type may be used alone, or two or more types may be mixed. For example, improving the solubility of polyamic acid by mixing a highly polar alcohol solvent with a solvent having relatively low solubility of polyamic acid such as acetone, ethyl acetate, methyl ethyl ketone, toluene, and xylene. Is also possible.

As shown in FIG. 1, in the polyamic acid production system, the first polymerizable substance and the second polymerizable substance, which are raw materials, are mixed in a solvent in the reaction unit 11 and the polymerization reaction is allowed to proceed to generate a polymerization solution A. It is configured to produce polyamic acids.

Next, the specific configuration of the polyamic acid production system will be described.
As shown in FIG. 1, the polyamic acid production system includes a reaction unit 11, a line for supplying raw materials and a solvent to the reaction unit 11, a supply pump 12, (first supply unit), a mixer unit 20, and a liquid feeding line. L and.

The reaction unit 11 is a portion for advancing the polymerization reaction between the supplied first polymerizable compound and the second polymerizable compound. In the present embodiment, the reaction unit 11 supplies a solvent, then tetracarboxylic acid dianhydride is supplied and mixed with the solvent to obtain a first reaction product solution, and then diamine is supplied to perform the first polymerization. By mixing with the sex substance solution, the polymerization reaction between the first polymerizable compound and the second polymerizable compound proceeds, and the polymerization solution A is obtained.

The first supply pump 12 (first supply unit) supplies the polymerization solution A obtained in the reaction unit 11 to the liquid feed line L and the mixer unit 20. The first supply pump 12 supplies the polymerization solution A in a predetermined liquid feeding amount. Although the mixer section 20 is used in the figure, the mixer section may be a pipe having no stirring function.

The mixer unit 20 is composed of a double tube extending in a predetermined direction, and has a stirring unit 21 arranged inside in the radial direction and a temperature adjusting unit 22 arranged outside in the radial direction. The mixer unit 20 is formed so that the polymerization solution A flows with a desired residence time.

The stirring unit 21 stirs the polymerization solution A in a state where it does not come into contact with the gas. In the present embodiment, the stirring unit 21 agitates the polymerization solution A in a state where it does not come into contact with the gas in order to efficiently cool the polymerization solution A by the temperature adjusting unit 22.

The stirring unit 21 is configured to include, for example, a static mixer such as a static mixer, a nozzle, an orifice, or a driven mixer such as a centrifugal pump, a centrifugal pump, or an in-line mixer having stirring blades, and is preferably a static mixer. It is configured to include a vessel, more preferably to include a static mixer.

The static mixer is not particularly limited, and for example, a Kenics mixer type, a SuLzer SMV type, a SuLzer SMX type, a Play Hi-mixer type, a Komax mixer type, a Lightnin mixer type, a Ross ISG type, a Ross ISG type, a Bran & Lube type, or the like. Can be mentioned. Among these, the Kenics mixer type static mixer is more preferable because it has a simple structure and therefore has no dead space.

As described above, the case where one of the first polymerizable compound and the second polymerizable compound is tetracarboxylic acid dianhydride and the other is diamine has been described, but the present invention is not limited thereto. For example, of the first polymerizable compound and the second polymerizable compound, one is a polyamic acid (prepolymer) having an acid anhydride group terminal or an amino group terminal, and the other is a diamine or tetracarboxylic acid dianhydride. May be good. In this case, of the first polymerizable compound and the second polymerizable compound, one is a polyamic acid having an acid anhydride group terminal, and the other is a diamine. Further, of the first polymerizable compound and the second polymerizable compound, one is an amino group-terminated polyamic acid and the other is a tetracarboxylic acid dianhydride.

In the polyamic acid production system of FIG. 1, after the polymerized polyamic acid solution is fed using the first supply pump 12, a highly viscous polyamic acid solution is present in the reaction section 11, the mixer section 20, and the liquid feed line L. do. When removing a high-viscosity polyamic acid solution from the reaction section, mixer section and liquid delivery line, a lower-viscosity polyamic acid solution is prepared in the reaction section and sent to the reaction section, mixer section and liquid delivery line. It can be washed efficiently by substituting the highly viscous polyamic acid inside.

A low-viscosity polymerization solution is obtained by supplying a solvent to the reaction section 11 and mixing with the polymerization solution A existing in the reaction section 11 to reduce the viscosity of the polymerization solution, and the high-viscosity polymerization solution is replaced with the low-viscosity polymerization solution. Therefore, it can be easily and efficiently washed.
Hereinafter, the low-viscosity polyamic acid solution for substituting the high-viscosity polymerization solution is referred to as a low-viscosity polymerization solution. Further, the “viscosity” referred to in the present specification is a value measured using an E-type viscometer under the conditions of a temperature of 23 ° C. and a shear rate of 0.38 s ^-1 .

After preparing the low-viscosity polymerization solution in the reaction section 11, the low-viscosity polymerization solution is supplied from the first supply section to the mixer section and the liquid feeding line, and the high-viscosity polymerization solution existing in the mixer section and the liquid feeding line is subjected to low-viscosity polymerization. Replace with solution. Further, by supplying a solvent to the reaction section, a polymerization solution having a viscosity lower than that of the low-viscosity polymerization solution is prepared. By repeating the above operation, the viscosity of the low-viscosity polymerization solution is gradually lowered in the range of 200 to 1000 poise while the liquid is sent, so that the high-viscosity polymerization solution can be washed without remaining inside the mixer section and the liquid feeding line. .. Regarding the preparation of the low-viscosity polymerization solution, the preparation may be carried out while continuously supplying the solvent, or the supply of the solvent and the preparation of the low-viscosity polymerization solution may be repeated in a step-by-step manner.

Hereinafter, the present invention will be specifically described with reference to Examples and Comparative Examples, but the present invention is not limited thereto.

(Example 1)
A 2000 poise polyamic acid N, N-dimethylformamide (hereinafter abbreviated as DMF) solution was prepared in the reaction section 11, and the solution was sent to a mixer section including a Kenics mixer type static mixer having an inner diameter of 8 mm. It was in a state of being filled with a polyamic acid solution. (Note that the viscosity is the viscosity at 23 ° C. measured with an E-type viscometer.)

In the reaction section 11, DMF is mixed with the high-viscosity polyamic acid to prepare 1000, 500, 250, 100, 70, 11 poise low-viscosity polyamic acids, and 25 mL each is sent to the mixer section in order from the one with the highest viscosity. Finally, 125 mL of DMF was sent.
As a result of observing the mixer part, all of them were replaced with DMF, and no polyamic acid solution remained.

(Comparative Example 1)
In the same manner as in the examples, the mixer section was filled with a 2000 poise polyamic acid solution, and 250 ml of DMF was sent to the mixer section for washing. As a result of observing the inside of the mixer, it was observed that the polyamic acid solution remained. Under the condition that the viscosity difference between the high-viscosity polyamic acid and N, N-dimethylformamide was large, the high-viscosity polyamic acid in the static mixer could not be completely removed.

1 Polyamic acid production system 11 Reaction section 12 1st supply pump (1st supply section)
20 Mixer part A Polymerization solution L Liquid delivery line

Claims (5)

It is an in-pipe cleaning method for cleaning the high-viscosity resin solution filled in the pipe, and the viscosity of the high-viscosity resin solution is 1200 to 4000 poise, and the same type of resin solution having a lower viscosity than the high-viscosity resin solution can be used. A method of cleaning the inside of a pipe by sending a liquid to replace the inside of the pipe, replacing the inside of the pipe with a resin solution of the same type having a lower viscosity than the resin solution of the previous term, and finally cleaning with an organic solvent. The in-pipe cleaning method according to claim 1, wherein the low-viscosity resin solution is prepared by diluting the high-viscosity resin solution with an organic solvent. The in-pipe cleaning method according to claim 1 or 2, wherein the low-viscosity resin solution is prepared using a batch-type mixing tank. The in-pipe cleaning method according to any one of claims 1 to 3, wherein the resin solution is a polyamic acid solution. The method for cleaning an inside of a tube according to any one of claims 1 to 4, wherein the tube is a static mixer.

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