JP3136749B2 - Cleaning method for liquid crystal polyester manufacturing equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for cleaning an apparatus for producing a liquid crystalline polyester.

[0002]

2. Description of the Related Art In recent years, liquid crystalline polyesters containing p-hydroxybenzoic acid as one component have been used for various electronic parts and industrial parts because of their excellent heat resistance and solvent resistance.

[0003] Since such polyesters have good solvent resistance, it is difficult to wash and remove polymers remaining on the apparatus after production. Conventionally, a cleaning method using an alkaline aqueous solution has been used.

However, the method of dissolving and decomposing a polymer using an alkaline aqueous solution has a problem that it takes an extremely long time for complete decomposition. Furthermore, depending on the polymer, complete decomposition was not possible in some cases. In such a case, a complicated method of disassembling the device and physically removing the device manually with an appropriate tool has been adopted.

[0005]

SUMMARY OF THE INVENTION An object of the present invention is to solve the problem that the conventional method for cleaning an apparatus for producing polyesters is not efficient and not economical.

[0006]

Means for Solving the Problems The present inventors have conducted intensive studies so as to solve such problems, and as a result, the present invention has been extremely concerned with a method of cleaning a production apparatus after removing a reaction product in the production of polyesters. They have come up with an efficient and economical way.

That is, the present invention relates to a method for cleaning an apparatus for producing a liquid crystalline polyester, which comprises using a mixture of a glycol and a primary or secondary amine for cleaning the apparatus for producing a liquid crystalline polyester.

The liquid crystalline polyester in the present invention includes polyesters obtained from aromatic hydroxycarboxylic acids such as p-hydroxybenzoic acid and 2-hydroxy-6-naphthoic acid, and those aromatic hydroxycarboxylic acids and terephthalic acid; Polyesters obtained from aromatic dicarboxylic acids such as isophthalic acid and 2,6-naphthalenedicarboxylic acid and aromatic dihydroxy compounds such as hydroquinone, resorcin, 4,4'-dihydroxydiphenyl, and 2,6-dihydroxynaphthalene. .

As an apparatus for producing a liquid crystalline polyester,
Production apparatuses and equipment such as a stirred tank reactor, a wet wall tower reactor, and a horizontal reactor are exemplified.

The glycols in the present invention include ethylene glycol, trimethylene glycol, triethylene glycol and the like.

The temperature at which the above-mentioned glycols are used for washing is preferably higher because the washing effect is higher.
Therefore, it is preferable to wash under reflux at a temperature near the boiling point of the glycol using the above-mentioned glycols. It is more preferred to wash under reflux at the boiling point of the glycol. It is preferable to use glycols having a high boiling point, but in consideration of price and the like, among the glycols described above,
Triethylene glycol (boiling point 287 ° C.) is preferred.

A primary or secondary amine is used in combination with the above glycols. The primary or secondary amines used in the present invention include alkylamines such as diethylamine, propylamine, dipropylamine, butylamine, dibutylamine and hexylamine, ethylenediamine, tetramethylenediamine, pentamethylenediamine, and alkylpolyamines such as diethylenetriamine. further,
Examples include aromatic amines such as aniline and benzylamine, and alkanolamines such as monoethanolamine and diethanolamine. Of these primary amines and secondary amines, monoethanolamine (boiling point: 171 ° C.) is preferable in consideration of the boiling point and price.

When a primary or secondary amine is used in combination, the washing effect is more excellent. Regarding the quantitative relationship between primary or secondary amines and glycols, it is appropriate that the concentration of primary or secondary amines is 5 to 50% by weight, preferably 10 to 30% by weight. When the concentration of the primary or secondary amine is less than 5% by weight, the effect of adding the primary or secondary amine is small, and when it exceeds 50% by weight, the reflux temperature cannot be increased, so that the washing effect is rather deteriorated. Absent.

[0014]

EXAMPLES Examples of the present invention will be shown below, but the present invention is not limited to these examples. As a method of evaluating the cleaning effect in Examples, separately synthesized polyester was pulverized, and a certain amount of a certain particle size was used.
Dispersed in a certain amount of solvent, treated at the temperature and time shown in the examples, cooled, filtered through an 80-mesh stainless steel wire mesh (opening: 0.18 mm), washed with methanol, dried, and placed on a wire mesh. The weight of the remaining polymer was measured and compared.

Reference Example (Production of Polyester A) 10.81 kg (60 mol) of p-acetoxybenzoic acid,
5.41 kg of 4,4′-diacetoxydiphenyl (20
Mol) and 3.32 kg (20 mol) of terephthalic acid were charged into a 50-liter SUS-316L polymerization tank having comb-shaped stirring blades. The temperature was raised in a nitrogen gas atmosphere, and the temperature was raised at a rate of 1 ° C./min with stirring from 180 ° C. to polymerize at 300 ° C. for 60 minutes while distilling off acetic acid as a by-product. Thereafter, the system was closed, the internal pressure of the vessel was maintained at 1 kg / cm ² · G with nitrogen, the valve at the bottom of the polymerization vessel was opened, and the reaction product was placed on a stainless steel tray for about 1 c.
m.

The yield of this reaction product was 13.41 kg, which was 99.2% of the theoretical yield. This is pulverized by a shearing type pulverizer comprising a fixed blade and a rotary blade, and the particle size is 3 mm or more and 8 m.
m or less were taken out and subjected to the washing test of the examples (hereinafter referred to as polyester A).

The repeating structural unit of the polyester A was represented by the general formula 1. The flow temperature of this polymer measured by the following method was 270 ° C.

[0018]

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Flow temperature: measured with a Koka type flow tester CFT-500 manufactured by Shimadzu Corporation and measured at 4 ° C. /
Resin heated and melted at a heating rate of
The temperature at which the melt viscosity shows 48,000 poise when extruded from a nozzle having an inner diameter of 1 mm and a length of 10 mm under cm ² . The lower the temperature of the resin, the greater the fluidity.

Comparative Example 1 A 500 ml cylindrical separable flask equipped with a glass squirrel type stirring blade, a cooling tube, a thermometer, and a nitrogen inlet tube and set in a mantle heater was used as a test device.

Using this apparatus, 10 g of the polyester A synthesized in Reference Example 1 and triethylene glycol (boiling point: 2
(87 ° C.), 300 ml, and treated at 287 ° C. under a nitrogen atmosphere with stirring at 150 rpm for 6 hours. Then 50 ° C
After cooling, the whole amount was filtered through an 80 mesh wire mesh, and no polymer particles remained on the wire mesh.

Comparative Example 2 The same operation as in Comparative Example 1 was carried out except that the treatment temperature was 200 ° C. When the stirring was stopped and the inside of the system was observed,
Since the presence of 2 mm particles was recognized, the mixture was further treated for 3 hours and filtered through a wire mesh. As a result, no polymer remained on the wire mesh.

Example 1 Similarly to Comparative Example 1, 10 g of polyester A synthesized in Reference Example 1, 270 ml of triethylene glycol and 30 ml of monoethanolamine were stirred at 250 ° C. for 2 hours. After cooling, the mixture was similarly filtered through a wire mesh, and no polymer remained.

Comparative Example 3 According to Comparative Example 1, instead of triethylene glycol, 15 g of caustic soda, 150 ml of water, 150 m of methanol were used.
The mixture was treated under a nitrogen atmosphere at 80 ° C. with stirring at 150 rpm for 8 hours. Stop stirring and observe the inside of the system.
Considerable particles were suspended. The next day, 5 more under the same conditions
The mixture was treated for an hour, filtered through a 80-mesh wire gauze, washed with methanol, dried, and weighed to be 4.1 g.
However, the shape of the particles was generally smaller. that's all,
Table 1 summarizes the results of Example 1 and Comparative Examples 1 to 3.

[0025]

[Table 1]

Comparative Example 4 21.6 kg of P-acetoxybenzoic acid (120 kg) was placed in a polymerization vessel made of 100 liter SUS-316L having a comb-shaped stirring blade.
Mol), 4,4'-diacetoxydiphenyl 10.8k
g (40 moles), 4.98 kg (30 moles) of terephthalic acid, and 1.66 kg (10 moles) of isophthalic acid.

The temperature was raised in a nitrogen gas atmosphere,
The temperature was raised at a rate of 1 ° C./min while stirring from the temperature of 300 ° C., and polymerization was carried out at 300 ° C. for 60 minutes while distilling off acetic acid as a by-product. After that, the system is closed and the tank pressure is 1 kg / cm ² · G with nitrogen gas.
, The valve at the bottom of the polymerization tank was opened, and the reaction product was drawn out to a stainless steel tray. The yield of this reaction is 26.0k.
In consideration of the theoretical yield in g, the amount of polymer remaining in the tank is about 1 kg. This polymer was pulverized into particles having an average particle size of 0.5 mm, and the flow temperature was measured.
° C.

This polymer is a wholly aromatic polyester comprising a repeating structural unit represented by the general formula (2).

[0029]

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When the inside of the tank was observed after cooling, the polymer was found to adhere to the tank wall and the stirring blade in a film form. Next, 60 liters of triethylene glycol is charged and washed at 287 ° C. under stirring and refluxing for 8 hours. After cooling, the contents are taken out, and when the inside of the tank is observed, all the sublimates adhered to the lid of the tank are removed. And the entire inside of the tank was clean.

Example 2 In the same manner as in Comparative Example 4, 100 liter SUS-316
In a polymerization tank made of L, a wholly aromatic polyester comprising a repeating structural unit represented by Formula 2 was polymerized. When the inside of the tank was observed after cooling, the polymer was found to adhere to the tank wall and the stirring blade in a film form. Next, 54 liters of triethylene glycol and 6 liters of monoethanolamine were charged and 25
After washing at 0 ° C. for 5 hours with stirring and refluxing, the contents were taken out after cooling, and when the inside of the tank was observed, all the sublimates adhered to the lid of the tank were removed, and the entire inside of the tank was clean.

[0032]

According to the present invention, since glycols are used for cleaning polyester production equipment and equipment and primary or secondary amines are used in combination, it is possible to adhere and remove residual polymer in a very short time. . In the treatment with the aqueous solution of caustic soda as in Comparative Example 3, it takes a very long time to completely dissolve and decompose, and depending on the polymer, it is impossible to completely dissolve and decompose, and the equipment and facilities are disassembled as necessary. It had to be physically removed with a knife.
On the other hand, according to the present invention, as is clear from the examples, the cleaning treatment can be performed very efficiently, and therefore, has a great industrial value.

────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁷ identification code FI C11D 7/32 C11D 7/32 (56) References JP-A-48-78297 (JP, A) JP-A-53-78313 (JP) , A) JP-A-48-63019 (JP, A) JP-B-47-46476 (JP, B1) British Patent Application Publication 1323886 (GB, A) (58) Fields investigated (Int. Cl. ⁷ , DB name ) C11D 7/26 B08B 3/08 B29C 33/72 C08G 63/78-63/90 C11D 7/32 CA (STN)

Claims (5)

(57) [Claims] 1. A method of cleaning a liquid crystalline polyester Le manufacturing apparatus characterized by using a mixture of glycols in cleaning liquid crystalline polyester Le of the manufacturing apparatus and primary or secondary amines. 2. The cleaning method according to claim 1 , wherein the glycol is at least one selected from ethylene glycol, trimethylene glycol, and triethylene glycol. 3. The amine is an alkyl monoamine, an alkyl
Select from polyamines, aromatic amines, and alkanolamines
The cleaning method according to claim 1 or 2, wherein the cleaning method is at least one kind . 4. Boiling point of a mixture of amines and glycols
The cleaning method according to any one of claims 1 to 3, which is performed below . 5. The method of claim 1 wherein the primary or secondary amines in the mixture are
5. The method according to claim 1, wherein the concentration is 5 to 50% by weight.
The cleaning method as described.