JPH06100893A - Method for cleaning polymerization apparatus - Google Patents

Abstract

PURPOSE:To remove by washing a condensation polymer deposited on an apparatus without impairing it and dispense with the nertralization step in the disposal of the cleaning fluid by using a cleaning fluid consisting of a polyhydric alcohol, an alkali (alkaline earth) metal hydroxide or a mineral acid, and water each in a specified amount for washing at a specified temperature an apparatus having a condensation polymer deposited thereon. CONSTITUTION:An apparatus (e.g. one made of stainless steel) having a condensation polymer (e.g. nylon 6) deposited thereon is washed at a temperature above the softening point of the polymer by using a cleaning fluid consisting of 69-99.89wt.% polyhydric alcohol (e.g. diethylene glycol), 0.1 to blow 1wt.% alkali (alkaline earth) metal hydroxide or mineral acid (e.g. NaOH), and 0.01-30wt.% water.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention repeatedly uses equipments to which condensation-type polymers are attached. Therefore, the adhesion-type condensation-type polymers have high detergency and have no adverse effect on the equipments. The present invention relates to a cleaning method of removing with a cleaning liquid that is easy to process.

[0002]

2. Description of the Related Art When a condensation type polymer is manufactured, it is necessary to clean the apparatus when the type of product is changed or when the adhered polymer is modified by a long-term operation and mixed into a product as a foreign substance. At that time, in order to wash and remove the polyamide adhering to the production apparatus for the condensation type polymer polyamide, a method of immersing the apparatus in a liquid in which a nitrate of an alkali metal or the like is dissolved at a high temperature and washing the same are used. A method of contacting with a dilute phosphoric acid solution at a high temperature has been adopted. However, these methods have the drawbacks that they modify and corrode the complicated and refined polyamide equipment, and they also generate postflammable gas, which requires post-treatment and poses a safety problem. was there.

Further, a cleaning solution containing only a solvent or a cleaning solution containing an additive has been proposed. However, none of them is sufficient as a cleaning agent, and the cleaning power is satisfactory, but the additive is neutralized. However, there was a problem in practical use due to the drawback that it was necessary. For example, in the specifications of German Patent Nos. 1,133,212 and 1,143,375, a method using a monohydric or polyhydric alcohol as a detergent is proposed.
This method has a problem that the ability to dissolve polyamide is low in the case of normal pressure, and it takes a long time to sufficiently wash, and the time is shorter than normal pressure even when the pressure is higher than the boiling point. However, there is a drawback that the detergency is not yet sufficient.

Further, Japanese Patent Publication No. 51-47447 proposes a method of using a composition obtained by adding a compound of an alkali metal or an alkaline earth metal or a mining product to a polyhydric alcohol as a cleaning agent. Has a problem that when the cleaning liquid after use is discarded, it must be neutralized with an acid or an alkali. Further, there is a drawback that when the mineral acid is used, the equipment material is corroded, while when the compound of the alkali metal or the alkaline earth metal is used, the equipment material is corroded and cracked.

[0005]

The present invention has a sufficiently high cleaning ability, and when the cleaning liquid is discarded, it does not require neutralization as in the conventional method, and there is no fear of corrosion of the material of the apparatus. It is an object of the present invention to provide a method for cleaning devices having a condensation polymer attached thereto.

[0006]

That is, the present invention comprises 69 to 99.89% by weight of polyhydric alcohols and 0.1 to 1 of alkali metal or alkaline earth metal hydroxides or mineral acids.
By using a cleaning liquid composed of 0.01% by weight and 0.01% by weight at a temperature equal to or higher than the softening point of the condensation-type polymer attached to the apparatus, the condensation-type polymer is removed from the apparatuses. A cleaning method consisting of a method of separating and removing, which has an excellent effect that the cleaning solution is easy to process because the cleaning solution does not have deformation, damage or adhesion and the pH of the cleaning solution is neutral or close to neutral. Is.

Examples of the polyhydric alcohols used in the present invention include methylene glycol-based, ethylene glycol-based, propylene glycols, diols such as glycerin, triols, and the like, with ethylene glycol and triethylene glycol being particularly preferred. is there.

Examples of hydroxides of alkali metals or alkaline earth metals include Li, Na, K, Mg, Ca and Ba.
And the like, and examples of the mineral acid include hydrochloric acid, sulfuric acid, nitric acid, phosphoric acid and the like. The amount of the alkali metal or alkaline earth metal hydroxide added was 0.
1% by weight to 1.0% by weight, especially 0.1% by weight to
0.5% by weight is preferred. If it is less than 0.1% by weight, the polymer may remain in the devices, which is not preferable.
If it exceeds 1.0% by weight, the pH of the solution becomes non-neutral, and it is necessary to neutralize the solution at the time of disposal.

The amount of water added is 0.01% by weight to 30% by weight, and particularly preferably 0.01% by weight to 5% by weight.
If it is less than 0.01% by weight or 30% by weight or more, the polymer may remain in the devices, which is not preferable.

The cleaning solution used in the present invention comprises the above-mentioned polyhydric alcohols and the above-mentioned alkali metal or alkaline earth metal hydroxides or mineral acids and water. May be added. The cleaning temperature is a temperature equal to or higher than the softening point of the polymer attached to the apparatus, and the apparatus attached with the polymer may be brought into contact with the cleaning liquid at that temperature. At this time, the cleaning time can be shortened by stirring the cleaning liquid, circulating it with a pump, or bubbling with an inert gas.

When the washing temperature is lower than the softening point of the polymer, the polymer remains and the purpose of washing and removing the polymer cannot be sufficiently achieved. The condensation polymer to which the cleaning liquid of the present invention is applied is a polymer such as polyamides such as nylon 6 or polyesters such as polyethylene terephthalate produced mainly by dehydration / dealcoholization reaction and copolymers thereof. It may be.

[0012]

EFFECTS OF THE INVENTION By washing the apparatus to which the condensation polymer is attached by the method of the present invention, the attached polymer (including its modified product) can be sufficiently washed and removed, and the apparatus can be washed at the time of washing. There is no risk of corrosion. Further, there is also an effect that it is not necessary to neutralize the cleaning waste liquid.

[0013]

EXAMPLES Next, examples of the present invention will be specifically described.

Production Example of Polyamideimide Elastomer 500 equipped with a stirrer, a nitrogen inlet and a distillation tube
In a ml separable flask, 97 g of caprolactam and 9 of polyoxyethylene glycol having a number average molecular weight of 1470.
0 g, trimellitic acid 16.4 g, and diphenylmethane diisocyanate 4.52 g were added to N, N-hexamethylene-
Charge with 0.3 g of bis (3,5-di-t-butyl-4-hydroxycinnamic acid amide) (trade name, Irganox 1098: antioxidant), and add nitrogen at 50 ml / mi.
It was melted at 150 ° C while flowing at n, and then polymerized at 260 ° C for 4 hours. 1 hour, 2 hours after reaching 260 ° C,
The water content in the reaction after 4 hours was 0.7, 0.5, and 0.3% by weight.

Then, after adding 0.3 g of tetrabutyl orthotitanate, the pressure was gradually reduced to 1 Torr and unreacted caprolactam was distilled out of the system. Further, polymerization was carried out at the same temperature under a pressure of 1 Torr or less for 2 hours to obtain a single yellow transparent elastomer (haze 46%). This elastomer has polyoxyethylene glycol segment 49
Wt%, relative viscosity 1.93, melting point 190
The crystallization temperature was 121 ° C and the decomposition temperature was 330 ° C.

Examples 1 to 4 A sample piece prepared by melting and adhering polyamide, polyamideimide elastomer, etc. on a stainless steel piece of SUS-304 was immersed in a glass flask containing a cleaning solution having the composition shown in Table 1, and made of glass. Was attached to the water-cooled reflux tube, and heated with a mantle heater at a predetermined temperature for a predetermined time. After cooling, the sample piece was taken out, washed with water, and then visually observed. The appearance and color tone of the sample piece were not changed as compared with those before heating. The results and the pH of the cleaning liquid after use are shown in Table 1. For the pH, take 50 ml of the washing solution after the test use,
After diluting to 250 ml, it was measured using a normal pH meter.

Comparative Examples 1 to 3 Samples were washed in the same manner as in Examples 1 to 4 except that the cleaning composition was changed as shown in Table 2, and the results are shown in Table 2. In Comparative Example 1, the polymer remained attached. Comparative Examples 2 and 3
No polymer adhered, but the pH of the washing solution showed strong alkali or strong acidity, and therefore the washing solution had to be neutralized when it was discarded. In addition, Comparative Example 3
It was confirmed that the test piece had some black spots and was clearly corroded.

[0018]

[Table 1]

[0019]

[Table 2]

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Claims (1)

[Claims] 1. Polyalcohols 69 to 99.89% by weight, and alkali metal or alkaline earth metal hydroxides or mineral acids 0.1 to less than 1% by weight, and water 0.01 to.
A method for cleaning a polymerization device, comprising: cleaning a device having a condensation-type polymer attached thereto at a temperature equal to or higher than a softening point of the attached polymer using a cleaning liquid of 30% by weight.