JPS6365203B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for cleaning and removing attached polyamide in order to reuse equipment that has become contaminated with polyamide. and dicarboxylic acid and/or dicarboxylic acid anhydride.
The present invention relates to a cleaning method that has high cleaning power by contacting at a temperature of 180° C. or higher, does not have an adverse effect on equipment, and furthermore allows easy processing of the cleaning liquid after use. Manufacturing equipment used in manufacturing polyamide fibers, such as polymerization equipment, molding equipment, spinning equipment, and their auxiliary equipment, becomes contaminated with polyamide during use. This adhered polyamide must be removed by washing when changing the type of polyamide or the type of polyamide composition. Further, the adhered polyamide may be denatured by long-term operation and become foreign matter that contaminates the product polyamide, and cleaning is also required in this case. Conventionally, in order to wash and remove polyamide adhering to polyamide production equipment, there have been two methods: cleaning the equipment by immersing it in a liquid in which nitrates of alkali metals, etc. are dissolved at high temperature, and cleaning the equipment by exposing it to hot sand. Methods such as washing or contacting with a high temperature dilute phosphoric acid solution have been adopted. These methods have the disadvantage of deforming or corroding the complex and sophisticated polyamide manufacturing equipment, and also generate flammable gas, requiring after-treatment, which poses safety issues. . In addition, various cleaning solutions using only organic solvents and additives have been proposed, but they are still insufficient as cleaning agents, or have satisfactory cleaning power but lack neutralization of additives. There were some drawbacks that were necessary, and there were practical problems. For example, German patent no.
The specifications of No. 1133212 and No. 1143375 propose a method using monohydric or polyhydric alcohol as a cleaning agent. In this method, the ability to dissolve polyamide is low under normal pressure, and it takes a long time to thoroughly clean the polyamide.Also, even if pressure is applied above the boiling point, the time is shorter than under normal pressure, but cleaning The drawback was that it was not yet powerful enough. Also, Tokko Akira
Publication No. 51-47477 proposes a method in which a composition in which an alkali metal or alkaline earth metal compound or a mineral acid is added to a polyhydric alcohol is used as a cleaning agent. must be neutralized with acid or alkali when disposed of; mineral acids may corrode the equipment material, while alkali metals or alkaline earth metal compounds may corrode the equipment material. The disadvantage was that there was a risk of corrosion cracking. The inventors of the present invention have developed the present invention as a result of extensive research into a cleaning solution that has sufficiently high cleaning ability, does not require neutralization when disposing of cleaning waste fluid, and does not cause corrosion to equipment materials. It is. That is, the present invention provides a cleaning solution consisting mainly of polyhydric alcohols and one or more compounds selected from the group of dicarboxylic acids and dicarboxylic acid anhydrides (hereinafter referred to as dicarboxylic acids) at a temperature of 180°C or higher. , a cleaning method in which the polyamide is separated and removed from the equipment by contacting the equipment with the polyamide attached,
It has excellent features in that there is no deformation, damage, or corrosion of equipment, and the pH of the cleaning fluid is neutral or close to neutral, making it easy to dispose of cleaning waste fluid. As the solvent for the cleaning liquid used in the present invention, polyhydric alcohols are used since they can be used with addition of dicarboxylic acids. Compounds that can be used as the polyhydric alcohols include diols and triols such as methylene glycol, ethylene glycol, propylene glycol, and glycerin, but particularly preferred are ethylene glycol, diethylene glycol, and triethylene glycol. . Compounds that can be used as dicarboxylic acids include succinic acid, methylsuccinic acid, glutaric acid, adipic acid, azelaic acid, sebacic acid, cyclohexanedicarboxylic acid, phthalic acid, isophthalic acid, terephthalic acid, succinic anhydride, methylsuccinic anhydride, Aliphatic compounds that do not decompose at the cleaning temperature, such as glutaric anhydride, maleic anhydride, phthalic anhydride, and compounds containing an alkyl group, alicyclic group, aromatic group, or heteroatom as a substituent in the main chain of these compounds, etc. , alicyclic and aromatic dicarboxylic acids and dicarboxylic acid anhydrides, among which aliphatic dicarboxylic acids and their anhydrides are preferred. If the boiling point of polyhydric alcohols and dicarboxylic acids used as cleaning liquids is less than 180℃,
A compound with a boiling point of 180°C or higher is preferable since it has the disadvantage that pressure must be applied when cleaning is carried out at a temperature of 180°C or higher. Similarly, in order to perform washing at normal pressure without pressurization, it is preferable to select a compound having a boiling point higher than the temperature during washing. The amount of dicarboxylic acids added is preferably 0.5% to 20% by weight, particularly preferably 1% to 10% by weight, based on the polyhydric alcohol.
If it is less than 0.5% by weight, it takes a long time to dissolve the polyamide and the polymer may remain in equipment, which is not preferable. Further, if the amount exceeds 20% by weight, the cleaning liquid becomes viscous or paste-like at room temperature, resulting in poor handling and workability, and it takes time to rinse the equipment after cleaning, which is not preferable. The cleaning liquid used in the present invention is composed of the polyhydric alcohols and the dicarboxylic acids, or is composed mainly of these.In addition to the two components mentioned above, other solvents may be used in combination within the range that does not impede the cleaning effect. It's okay. The cleaning temperature may be 180° C. or higher and the equipment on which polyamide is attached may be brought into contact with the cleaning liquid. The cleaning time can also be accelerated by stirring the cleaning solution, circulating it with a pump, or bubbling it with an inert gas. The cleaning liquid used in the present invention has a sufficiently good cleaning effect even without pressurization if it is washed at 180°C or higher, so cleaning under normal pressure is preferable from the viewpoint of cleaning equipment. There is no problem. When washing at a temperature higher than the boiling point of each component of the washing liquid, it is preferable to use a pressure cooker to carry out the washing under pressure, but it may also be carried out under normal pressure by attaching a reflux device. Furthermore, even when cleaning is performed at a temperature below the boiling point, it is desirable to install a reflux device to prevent the cleaning liquid from evaporating, and to perform the process without causing any safety problems. If the cleaning temperature is less than 180℃, it will take a long time to dissolve the polyamide, or the polymer will remain in the equipment, making it impossible to fully achieve the purpose of cleaning and removing the polyamide.
It is necessary to wash with the above. When polyamide attachment devices are cleaned using the method of the present invention, the attached polyamide (including its modified products) can be sufficiently washed away, and there is no risk of corrosion of the attachments during cleaning. , suitable as a method for cleaning polyamide deposition equipment such as spinnerets, spinning packs, and polymerization kettles;
In particular, since there is no risk of corrosion of attachments, it is suitable as a method for cleaning equipment that requires precision, such as spinnerets and spinneret parts in spinning packs. Another advantageous effect is that there is no need to neutralize cleaning waste liquid when disposing of it. Next, the present invention will be specifically explained by giving examples. Example 1 A spinneret used for spinning nylon 6 and coated with polyamide was placed in a metal basket, and the basket and the spinneret were placed in a tank containing a cleaning solution consisting of 100 parts by weight of diethylene glycol and 5 parts by weight of succinic acid. Soaked. Next, a water-cooled reflux device is attached,
Heating was started while bubbling nitrogen gas from the bottom of the tank. After being kept at 240°C for 3 hours, the cleaning solution was drained, the basket was allowed to cool naturally, the spinneret was taken out, water washing, ultrasonic washing, and water washing were repeated twice, and the spinneret was dried by air blowing. When this spinneret was observed under a microscope, no adhesion of nylon 6 polymer was observed within the spinneret holes. This cleaning solution was subsequently used five times to clean spinnerets, porous metals, filters, and other spinnerets to which nylon 6 polymer had adhered, but no deposits remained on the spinnerets or spinneret parts after cleaning. Nakatsuta. We took 50 ml of the cleaning solution after 5 uses and diluted it with water to 250 ml. The pH of the solution was 4.7, and the pH of the cleaning solution after 1 use was 4.2, so we were able to discard it without neutralizing it. . Example 2 After completing the polymerization of nylon 66 and discharging the polymer, the volume of polymer adhering to the inner wall was 100.
A cleaning solution 75 consisting of 100 parts by weight of triethylene glycol and 4 parts by weight of adipic acid was charged into the polymerization kettle, and after it was sealed, heating and stirring were started.
The temperature was maintained at 260°C for 2 hours, and then cooling was started, and when the temperature reached 100°C, the washing liquid was drawn out from the bottom of the polymerization vessel. Fill the polymerization pot with water preheated to 950℃,
After stirring for 20 minutes, the water was drained and washing was repeated twice with room temperature water. After washing with water, the polymerization pot was disassembled and the inner wall and stirring rod were inspected, and as a result, no polymer was attached at all. After use, rinse the cleaning solution with water for 5 minutes.
Since the pH of the diluted solution was 4.5, it could be discarded without neutralization. Examples 3 to 10 Using a sample piece of SUS-304 stainless steel to which various polyamides were melted and adhered, a glass flask containing a cleaning solution having the composition shown in Table 1 was placed in an air-cooled reflux device made of a glass tube. The sample was then heated using a mantle heater at a predetermined temperature and time while bubbling nitrogen gas. After cooling, take out the sample piece and
After washing with water, the sample pieces were visually observed. The results and the pH of the cleaning solution after use are shown in Table 1. The method for measuring the pH of the cleaning solution was the same as in Example 1. Note that no change was observed in the appearance and color tone of the sample piece compared to before heating.

【table】

[Table] Comparative Examples 1 to 5 Sample pieces were cleaned in the same manner as Examples 3 to 8, except that the cleaning solution composition was changed as shown in Table 2. The results are shown in Table 2. In Comparative Examples 1 and 2, residual polymer remained attached. In Comparative Examples 3, 4, and 5, there was no polymer adhesion at all, but the pH of the cleaning solution was strongly alkaline or acidic, so the cleaning solution had to be neutralized when discarded. In addition, in Comparative Example 5, the cleaning liquid turned black, and some of the sample pieces had black spots, indicating that they were clearly corroded.

【table】

Claims (1)

[Claims] 1. A cleaning liquid mainly consisting of polyhydric alcohols and one or more compounds selected from the group of dicarboxylic acids and dicarboxylic acid anhydrides is brought into contact with equipment on which polyamide is attached at a temperature of 180°C or higher,
A method for cleaning equipment to which polyamide is attached, characterized in that the polyamide is removed by washing.