JPS61192748A - Method for washing polymer containing unsaturated bond in molecule - Google Patents

Abstract

PURPOSE:To dissolve and remove a polymer deposited on an object inexpensively in a short time without requiring any manual operation or any physical removing means, by bringing a polymer contg. unsaturated bonds in the molecule deposited on an object into contact with a cleaning agent contg. an alkali and an oxygen-donating agent. CONSTITUTION:A polymer contg. unsaturated bonds in the molecule deposited on an object is brought into contact with a cleaning agent contg. an alkali and an oxygen-donating agent for a period of time sufficient to dissolve said polymer in said cleaning agent. Examples of the polymers are those of acrylonitrile, methacrylate ester and hydrocyanic acid. Examples of the alkalis are caustic soda and caustic potach. Examples of the oxygen-donating agents are potassium permanganate, potassium dichromate and hydrogen peroxide. As the solvent for the cleaning agent, water is preferred. Pref. the amount of the alkali in the solvent is 1-10wt% and the preferred weight ratio of the alkali to the oxygen-donating agent is 1/0.5-1/0.8.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a method for cleaning and removing polymers having unsaturated bonds in their molecules that adhere to objects, such as equipment such as chemical plants.

(Prior Art) Conventionally, a cleaning method has generally been used in which such equipment, such as a distillation tower, is dismantled and the polymer adhering to the tray is physically removed manually. Attempts have also been made to chemically clean the surface using an alkaline agent such as caustic soda.

(Problems to be Solved by the Invention) The manual method described above has drawbacks such as requiring a long time for cleaning and the like, and also requiring a large amount of money for this maintenance work. Furthermore, chemical cleaning simply causes the adhered polymer to swell, and physical removal is usually required to remove it from the device.

(Means for Solving the Problems) As a result of intensive research to improve this drawback, the present inventor found that after a polymer having unsaturated bonds such as C=C in its molecules was swollen with an alkaline agent, oxygen The present invention was completed based on the knowledge that it is possible to dissolve in the presence of and remove it from the apparatus.

That is, the present invention, when cleaning and removing a polymer having unsaturated bonds in its molecules attached to an object, for example, a device, uses a cleaning agent containing an alkaline agent and an oxygen donor and the polymer by releasing oxygen from the oxygen donor and using an alkaline agent. A method for cleaning deposited polymers characterized by contacting for a sufficient period of time for the polymer to swell and then be dissolved by the released oxygen.

(Main body structure) The polymer to be removed by the present invention is a polymer having an unsaturated bond in the molecule.

Examples of unsaturated bonds include C═C, CAN, and combinations thereof, such as unsaturated nitriles such as acrylonitrile, methacrylic acid ester, acetonitrile, and hydrocyanic acid. Examples of such polymers having unsaturated nitriles include acrylonitrile polymers, meccrylic acid ester polymers, and hydrocyanic acid polymers.

Examples of alkaline agents in the cleaning agent used in the present invention include caustic soda and potassium hydroxide. Oxygen donors used in the present invention include potassium permanganate, potassium dichromate, hydrogen peroxide, and the like.

The solvent in the cleaning agent is not particularly limited as long as it dissolves the alkali agent and oxygen donor and does not corrode the equipment. Preferably water is used.

The concentration of the alkaline agent and oxygen donor in the solvent varies depending on the characteristics of the polymer to be removed, its amount, and the proportion of the cleaning agent, but in -a, the alkaline agent is added at 0.5% by weight or more, preferably from 0.5% to 0.5% by weight. The content is preferably 15% by weight, more preferably 1 to 10% by weight.

Weight ratio of alkaline agent and oxygen donor in the above cleaning agent: 1:
The ratio is preferably 0.4 to 1:1, preferably 1:0.5 to 1:0.8.

Methods for bringing the cleaning agent into contact with the polymer include circulating the cleaning agent within the device to which the polymer is attached, or immersing the device in a cleaning solution. The contact conditions first require sufficient temperature and time for the oxygen donor in the cleaning agent to release oxygen into the liquid.

The temperature may be room temperature, but generally the higher the temperature, the faster the polymer dissolution rate. Usually room temperature to 100℃, preferably 50℃ to
It can be done at 90℃.

The contact time is related to the amount of polymer to be removed;
Usually about 2 hours, preferably 2 to 10 hours.

After cleaning according to the method of the present invention, it is preferable to neutralize the remaining alkaline agent in the apparatus as a post-treatment, if necessary. For example, sulfuric acid or the like is used as a neutralizing agent, and the neutralization treatment is performed to obtain p116-8.

(Effects of the Invention) The method of the present invention does not require physical polymer removal operations such as conventional manual removal or chemical treatment using only an alkaline agent, and dissolves and removes adhering polymers economically and inexpensively in a short time. I can do it.

(Example) Next, examples of the present invention will be described.

Example 1 Calcium hydroxide or sodium chloride was used as an alkaline agent, potassium permanganate or potassium dichromate was used as an oxygen donor, and water was used as a solvent.

As the target polymer, an attached polymer of an acrylonitrile polymer, a hydrocyanic acid polymer, and a methacrylic acid ester polymer produced in the acrylonitrile or methacrylonitrile manufacturing process was used.

The target polymer adhering to the polymer was immersed in a container in which the cleaning solution could be circulated using a pump, and the polymer was immersed at a temperature of 80°C for 4 hours.
Table 1 shows the results of investigating the swelling and dissolution of the polymer by circulating the cleaning solution of J. Experimental floor 4.8.12 in Table 1 is a comparative example. From the results in Table 1, according to the method of the present invention,
It will be appreciated that the polymer should be paper-like, fragmented or completely sludge-like, and should be dissolved and easily removed.

Below is a blank space Example 2 2g of acrylonitrile polymer was mixed with an alkali agent (potassium hydroxide), 7% by weight, an oxygen donor (permanganate acid power 1
Table 2 shows the results of immersion circulation at a temperature of 80°C at each concentration shown in Table 2 using a 3% by weight cleaning agent.

The solvent for the alkali agent and oxygen donor is water, each with a concentration of 1000.
ml! Using.

Below is a blank table 2 Example 3 2 g each of acrylonitrile polymer and cyanide polymer samples were mixed with 3.5 g of an alkaline agent (Ijium hydroxide).
Grain %, oxygen donor (permancanic acid power IJ) 1.5
The experiment was carried out in the same manner as in Example 1 since the solvent was water and a washing solution of 11% by weight was used. However, Table 3 shows the results obtained by changing the temperature as shown in Table 3.

Margin below Table 3

Claims (1)

[Claims] A polymer having an unsaturated bond in the molecule attached to an object is brought into contact with a cleaning agent containing an alkaline agent and an oxygen donor for a sufficient period of time to dissolve the polymer. A method for cleaning polymers containing unsaturated bonds.