Cleaning agent for effectively removing carbides of polyester prepolymerization filter

Abstract

The invention relates to the technical field of polyester filament production, and discloses a cleaning agent for effectively removing carbides of a polyester prepolymerization filter and an application method of the cleaning agent. The cleaning agent is composed of 2-10% of an alkaline agent, 5-15% of a surfactant and the balance of water, the alkaline agent is selected from one or more of sodium hydroxide, potassium hydroxide and sodium bicarbonate, and the surfactant is selected from one or more of fatty alcohol-polyoxyethylene ether and other four compounds. When the cleaning agent is applied, a pre-polymerized filter subjected to hydrolysis and alkali washing is placed in an ultrasonic cleaning machine containing the cleaning agent to be cleaned for 30-60 min at the temperature of 30-70 DEG C, and the pre-polymerized filter can be prepared after being dried and assembled. Through the synergistic effect of the alkaline agent and the surfactant and in combination with ultrasonic and heating energizing, residual carbides in the filter element can be thoroughly stripped, thermal degradation of a melt is avoided, and the quality of downstream filaments is guaranteed; and meanwhile, the service cycle of the filter is prolonged, the cleaning and production cost is reduced, and the filter is suitable for different polyester melt production scenes such as semi-dull and bright polyester melts and has wide application prospects.

Description

Technical Field

[0001] This invention relates to the field of polyester filament production technology, specifically to a cleaning agent that effectively removes carbon deposits from polyester prepolymer filters. It is particularly suitable for deep cleaning of residual carbon deposits in the prepolymer filter element during polyester melt spinning, thereby ensuring melt cleanliness and downstream product quality. Background Technology

[0002] In the polyester filament production process, the melt filter is one of the key pieces of equipment. Its core component, the filter element, is made of stainless steel fiber felt, which is resistant to high temperature, high pressure, and corrosion, and can be repeatedly washed and reused. The main function of this filter is to separate agglomerated particles and mechanical impurities contained in the polyester melt, ensuring the cleanliness of the melt entering the subsequent spinning process, thereby guaranteeing the physical properties and appearance quality of the filament products.

[0003] During polyester polymerization and melt transport, oligomers and small molecule compounds are easily generated. These substances enter the ethylene glycol hot well via the gas phase pipeline with ethylene glycol vapor, and then flow sequentially into the ethylene glycol recovery tank and slurry tank. During multiple cycles of reuse, under the influence of high temperature and long residence time, they are prone to thermal polymerization and carbonization reactions, forming hard carbide particles. These carbide particles gradually accumulate inside and on the surface of the prepolymer filter element as the melt flows. Even with regular filter replacement and cleaning, some stubborn carbides remain in the tiny pores of the filter element, making them difficult to completely remove.

[0004] In existing technologies, the treatment of residual carbides often involves removing them through prolonged filling and venting during the next filter switchover. However, this method has significant drawbacks: Firstly, prolonged filling and venting significantly increases the residence time of the polyester melt in the system, leading to unnecessary thermal degradation. This not only causes the melt to turn yellow and degrade in quality but also directly affects key indicators such as the breaking strength and evenness of downstream filaments. Secondly, the venting process results in substantial melt waste, increasing production costs, extending the production cycle, and reducing production efficiency. Furthermore, the continuous accumulation of residual carbides accelerates the rise in filter differential pressure, shortens the filter's lifespan, increases the frequency of filter element cleaning and equipment maintenance costs, and further impacts the continuity and stability of production.

[0005] To address the aforementioned technical challenges, there is an urgent need to develop a highly efficient, mild, and environmentally friendly cleaning agent capable of deeply removing residual carbide particles from the filter element without damaging its structure and performance. This would reduce the risk of melt quality degradation during filter switching, extend the filter's service life, and achieve the production goals of improving quality and reducing costs. Based on this, this invention proposes a technical solution that combines effective cleaning with practicality through a systematic study of the cleaning agent's components, formulation, and application process. Summary of the Invention

[0006] The core objective of this invention is to provide a cleaning agent that effectively removes carbon deposits from polyester prepolymer filters, thereby solving the problems in the prior art such as the difficulty in removing residual carbon deposits from prepolymer filter cartridges, melt thermal degradation during filter switching, impact on product quality, and high production costs.

[0007] To achieve the above objectives, the present invention adopts the following technical solution:

[0008] A cleaning agent for effectively removing carbon deposits from polyester prepolymer filters, including cleaning agent preparation and application steps:

[0009] (1) Preparation of cleaning agent: by weight percentage, it is made by mixing 2-10% alkali, 5-15% surfactant and the balance water evenly;

[0010] (2) Ultrasonic cleaning: The prepolymer filter after conventional hydrolysis and alkaline washing is placed in an ultrasonic cleaner containing the cleaning agent for cleaning;

[0011] (3) Follow-up processing: Dry and assemble the cleaned filter element, and switch to use when the online filter pressure difference reaches the standard.

[0012] Furthermore, the alkaline agent is selected from one or more combinations of sodium hydroxide, potassium hydroxide, and sodium bicarbonate.

[0013] Furthermore, the surfactant is selected from one or more combinations of fatty alcohol polyoxyethylene ether, coconut oil fatty acid diethanolamide, dehydrated sorbitan monostearate, polyoxyethylene sorbitan monolaurate, dodecyl dimethyl benzyl ammonium chloride, and hexadecyl trimethyl ammonium bromide.

[0014] Furthermore, the pH value of the cleaning agent is 9-14.

[0015] Furthermore, the temperature for ultrasonic cleaning is 30-70℃.

[0016] Furthermore, the ultrasonic cleaning time is 30-60 minutes.

[0017] Furthermore, the polyester is either a semi-dull polyester melt or a bright polyester melt.

[0018] Furthermore, when the alkali agent is a combination of two or more, the weight percentage of each component is 1-8%, and the total percentage does not exceed 10%.

[0019] Furthermore, when there are two or more surfactants in combination, the weight percentage of each component is 1-10%, and the total percentage does not exceed 15%.

[0020] Furthermore, the ultrasonic cleaner has a power of 100-500W and an ultrasonic frequency of 20-80kHz.

[0021] This invention provides a cleaning agent that effectively removes carbon deposits from polyester prepolymer filters, compared with existing technologies:

[0022] Thorough cleaning effect and high carbon removal rate: Through the chemical action of alkali and surfactant, combined with the physical energy of ultrasound and heating, deep cleaning of residual carbon in the filter element is achieved, with a removal rate of over 95%, effectively solving the problem that traditional cleaning methods are difficult to remove stubborn carbon.

[0023] Ensuring melt quality and improving product stability: When switching to a cleaned filter, there are no obvious residual carbides in the melt, and the normal color can be restored without long-term waste discharge. This avoids yellowing and performance degradation caused by melt thermal degradation, ensuring the quality stability of downstream filament products. After testing, the L value of polyester chips after switching remains above 60.8, and the b value is controlled below 2.3.

[0024] Extend the service life of filters and reduce production costs: The filter element is thoroughly cleaned, with no carbon deposits on the surface and in the internal pores. The rate of increase in the pressure difference of the filter is significantly slowed down, and the service life is extended by 5-10 days compared with traditional cleaning methods. This greatly reduces the frequency of filter element cleaning, equipment maintenance costs and melt waste loss.

[0025] Gentle and non-damaging, protecting filter elements and equipment: The pH value of the cleaning agent is controlled between 9 and 14, and the alkalinity can be adjusted by sodium bicarbonate to avoid corrosion of stainless steel fiber felt filter elements. At the same time, the cleaning agent does not damage equipment such as ultrasonic cleaners, ensuring the reusability of equipment and filter elements.

[0026] The process is simple and efficient, and suitable for industrial production: the cleaning agent is easy to prepare, the ultrasonic cleaning process does not require manual intervention, batch processing can be achieved, the cleaning time is only 30-60 minutes, the subsequent drying and assembly processes are simple, it is highly compatible with existing production processes, and it is easy to promote and apply industrially.

[0027] Wide range of applications and adaptable to different production scenarios: The cleaning agent and cleaning method of the present invention have good removal effect on carbides generated during the production of different types of polyester melts (semi-dull and bright). At the same time, the cleaning agent composition ratio and cleaning process parameters can be flexibly adjusted according to the residual amount of carbides to adapt to different production conditions. Detailed Implementation

[0028] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to specific embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0029] Example 1

[0030] A cleaning agent for effectively removing carbon deposits from polyester prepolymer filters, the preparation and application methods are as follows:

[0031] (1) Prepare a cleaning agent for cleaning polyester prepolymer filters. The cleaning agent consists of 5% sodium hydroxide, 5% fatty alcohol polyoxyethylene ether, and 90% water. Mix well and set aside.

[0032] (2) Place the prepolymer filter after conventional hydrolysis and alkaline washing in an ultrasonic cleaner with added cleaning agent and ultrasonically clean it for 30 min at 30°C.

[0033] (3) Dry and assemble the filter element after ultrasonic cleaning, and switch it when the pressure difference of the filter on the line is high.

[0034] Example 2

[0035] A cleaning agent for effectively removing carbon deposits from polyester prepolymer filters, the preparation and application methods are as follows:

[0036] (1) Prepare a cleaning agent for cleaning polyester prepolymer filters. The cleaning agent consists of: 5% potassium hydroxide, 5% fatty alcohol polyoxyethylene ether, 5% coconut oil fatty acid diethanolamide, and 85% water. Mix well and set aside.

[0037] (2) Place the prepolymer filter after conventional hydrolysis and alkaline washing in an ultrasonic cleaner with added cleaning agent and ultrasonically clean it for 60 min at 40°C.

[0038] (3) Dry and assemble the filter element after ultrasonic cleaning, and switch it when the pressure difference of the filter on the line is high.

[0039] Example 3

[0040] A cleaning agent for effectively removing carbon deposits from polyester prepolymer filters, the preparation and application methods are as follows:

[0041] (1) Prepare a cleaning agent for cleaning polyester prepolymer filters. The cleaning agent consists of: 3% sodium hydroxide, 5% potassium hydroxide, 5% fatty alcohol polyoxyethylene ether, 5% dehydrated sorbitan monostearate, and 82% water. Mix well and set aside.

[0042] (2) Place the prepolymer filter after conventional hydrolysis and alkaline washing in an ultrasonic cleaner with added cleaning agent and ultrasonically clean it for 50 min at 50°C.

[0043] (3) Dry and assemble the filter element after ultrasonic cleaning, and switch it when the pressure difference of the filter on the line is high.

[0044] Example 4

[0045] A cleaning agent for effectively removing carbon deposits from polyester prepolymer filters, the preparation and application methods are as follows:

[0046] (1) Prepare a cleaning agent for cleaning polyester prepolymer filters. The cleaning agent consists of: 3% sodium hydroxide, 2% potassium hydroxide, 5% sodium bicarbonate, 5% fatty alcohol polyoxyethylene ether, 2% dehydrated sorbitan monostearate, 3% polyoxyethylene sorbitan monolaurate, and 80% water. Mix well and set aside.

[0047] (2) Place the prepolymer filter after conventional hydrolysis and alkaline washing in an ultrasonic cleaner with added cleaning agent and ultrasonically clean it for 40 minutes at 60°C.

[0048] (3) Dry and assemble the filter element after ultrasonic cleaning, and switch it when the pressure difference of the filter on the line is high.

[0049] Example 5

[0050] A cleaning agent for effectively removing carbon deposits from polyester prepolymer filters, the preparation and application methods are as follows:

[0051] (1) Prepare a cleaning agent for cleaning polyester prepolymer filters. The cleaning agent consists of: 6% sodium hydroxide, 4% sodium bicarbonate, 5% fatty alcohol polyoxyethylene ether, 5% coconut oil fatty acid diethanolamide, and 80% water. Mix well and set aside.

[0052] (2) Place the prepolymer filter after conventional hydrolysis and alkaline washing in an ultrasonic cleaner with added cleaning agent and ultrasonically clean it for 30 minutes at 70°C.

[0053] (3) Dry and assemble the filter element after ultrasonic cleaning, and switch it when the pressure difference of the filter on the line is high.

[0054] Example 6

[0055] A cleaning agent for effectively removing carbon deposits from polyester prepolymer filters, the preparation and application methods are as follows:

[0056] (1) Prepare a cleaning agent for cleaning polyester prepolymer filters. The cleaning agent consists of: 2% sodium hydroxide, 5% fatty alcohol polyoxyethylene ether, 5% coconut oil fatty acid diethanolamide, 5% polyethylene oxide sorbitol monolaurate, 5% dodecyl dimethyl benzyl ammonium chloride, 5% hexadecyl trimethyl ammonium bromide, and 73% water. Mix well and set aside.

[0057] (2) Place the prepolymer filter after conventional hydrolysis and alkaline washing in an ultrasonic cleaner with added cleaning agent and ultrasonically clean it for 40 minutes at 50°C.

[0058] (3) Dry and assemble the filter element after ultrasonic cleaning, and switch it when the pressure difference of the filter on the line is high.

[0059] Comparative Example 1

[0060] A cleaning agent for effectively removing carbon deposits from polyester prepolymer filters, the preparation and application methods are as follows:

[0061] (1) Prepare a cleaning agent for cleaning polyester prepolymer filters. The cleaning agent consists of 5% sodium hydroxide and 95% water. Mix well and set aside.

[0062] (2) Place the prepolymer filter after conventional hydrolysis and alkaline washing in an ultrasonic cleaner with added cleaning agent and ultrasonically clean it for 40 minutes at 50°C.

[0063] (3) Dry and assemble the filter element after ultrasonic cleaning, and switch it when the pressure difference of the filter on the line is high.

[0064] Comparative Example 2

[0065] A cleaning agent for effectively removing carbon deposits from polyester prepolymer filters, the preparation and application methods are as follows:

[0066] (1) Prepare a cleaning agent for cleaning polyester prepolymer filters. The cleaning agent consists of 5% fatty alcohol polyoxyethylene ether and 95% water. Mix well and set aside.

[0067] (2) Place the prepolymer filter after conventional hydrolysis and alkaline washing in an ultrasonic cleaner with added cleaning agent and ultrasonically clean it for 40 minutes at 50°C.

[0068] (3) Dry and assemble the filter element after ultrasonic cleaning, and switch it when the pressure difference of the filter on the line is high.

[0069] Comparative Example 3

[0070] A cleaning agent for effectively removing carbon deposits from polyester prepolymer filters, the preparation and application methods are as follows:

[0071] (1) Prepare a cleaning agent for cleaning the polyester prepolymer filter. The cleaning agent consists of 100% water.

[0072] (2) Place the prepolymer filter after conventional hydrolysis and alkaline washing in an ultrasonic cleaner with added cleaning agent and ultrasonically clean it for 40 minutes at 50°C.

[0073] (3) Dry and assemble the filter element after ultrasonic cleaning, and switch it when the pressure difference of the filter on the line is high.

[0074] Table 1. Pressure difference changes during filter use after cleaning in Example 1.

[0075]

[0076] Table 2. Pressure difference changes during filter use after cleaning in Example 3.

[0077]

[0078] Table 3. Color of polyester chips after filter switching in Examples 1-6

[0079]

[0080] Table 4 shows the pressure difference of the filters after 30 days of use following cleaning in Comparative Examples 1-3.

[0081]

[0082] Tables 1 and 2 show the pressure difference changes of the filters after cleaning in Examples 1 and 3 during use. As can be seen from the tables, the filter pressure difference was 0.57 and 0.55 MPa after 35 days of use, respectively. Compared to Comparative Examples 1-3 (Table 4), the pressure difference after 30 days of use was significantly reduced, and the filter's service life could be extended by at least 5 days. Table 3 shows the color of the polyester chips after filter switching in Examples 1-6. As can be seen from the table, the polyester chips still had a high L value and a low b value after filter switching, proving that the cleaning agent provided by this invention provides a certain guarantee for the color of the polyester chips during filter switching.

[0083] In summary, the cleaning agent that should have removed the carbides from the polyester prepolymer filter was:

[0084] This patent, through the synergistic design of cleaning agent components, optimization of process parameters, and innovation of the mechanism of action, has formed a technical solution that combines high efficiency, practicality, and economy. Its core advantages can be summarized in the following six aspects:

[0085] 1. Thorough cleaning effect with high carbon removal rate

[0086] By employing a scientifically formulated ratio of 2-10% alkali and 5-15% surfactant, combined with heating at 30-70℃ and ultrasonic activation at 100-500W, a synergistic effect of chemical decomposition and physical stripping is achieved. The surfactant reduces interfacial tension, promoting the penetration of the alkaline aqueous solution into the filter element pores; the alkali breaks the chemical bonds of carbides; and the ultrasonic shockwave removes stubbornly adhered particles, achieving a carbide removal rate of over 95%, completely solving the problem of residue from traditional cleaning methods.

[0087] II. Protects equipment and filter elements, with excellent reusability.

[0088] The pH value of the cleaning agent is controlled between 9 and 14, and the alkalinity can be flexibly adjusted with sodium bicarbonate to avoid corrosion of the stainless steel fiber felt filter element. After cleaning, the tensile strength of the filter element decreases by less than 3%. At the same time, the cleaning agent does not damage equipment such as ultrasonic cleaners, ensuring the long-term reusability of equipment and filter elements and reducing the cost of replacing parts.

[0089] III. Ensure melt quality and stabilize product quality

[0090] When switching back to the cleaned filter, there are no residual carbides in the melt, and the normal color can be restored without prolonged waste discharge, avoiding the yellowing problem caused by melt thermal degradation. Testing showed that after switching, the L-value of the polyester chips remained above 60.8, and the b-value was controlled below 2.3, effectively ensuring the stability of the physical properties and appearance quality of the downstream filaments.

[0091] IV. Extend the service life and reduce production costs

[0092] With no carbon deposits in the filter element pores, the rate of increase in filter differential pressure is significantly slowed down, and the service life is extended by 5-10 days compared to traditional cleaning methods. At the same time, it reduces the frequency of filter element cleaning, melt waste discharge loss, and equipment maintenance, thereby reducing the overall production cost from multiple dimensions and achieving the goal of improving quality and reducing costs.

[0093] V. The process is simple and efficient, and suitable for industrial production.

[0094] The cleaning agent only requires mixing of alkali, surfactant and water. The ultrasonic cleaning process requires no manual intervention, can be processed in batches, and the cleaning time is only 30-60 minutes. The subsequent drying and assembly processes are simple. It is highly compatible with existing polyester production processes, does not require modification of existing equipment, and is easy to promote and apply on a large scale.

[0095] VI. Wide range of applications, adaptable to diverse scenarios

[0096] The cleaning agent composition and process parameters can be flexibly adjusted, and it has a good removal effect on carbides generated by different types of polyester melts, such as semi-dull and bright. At the same time, the ratio of alkali agent and surfactant and ultrasonic parameters can be optimized according to actual working conditions such as carbide residue and filter cartridge usage time to adapt to different production needs.

[0097] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A cleaning agent for effectively removing carbon deposits from polyester prepolymer filters, characterized in that, Including cleaning agent preparation and application steps: (1) Preparation of cleaning agent: by weight percentage, it is made by mixing 2-10% alkali, 5-15% surfactant and the balance water evenly; (2) Ultrasonic cleaning: The prepolymer filter after conventional hydrolysis and alkaline washing is placed in an ultrasonic cleaner containing the cleaning agent for cleaning; (3) Follow-up processing: Dry and assemble the cleaned filter element, and switch to use when the online filter pressure difference reaches the standard.

2. The cleaning agent according to claim 1, characterized in that, The alkaline agent is selected from one or more combinations of sodium hydroxide, potassium hydroxide, and sodium bicarbonate.

3. The cleaning agent according to claim 1, characterized in that, The surfactant is selected from one or more combinations of fatty alcohol polyoxyethylene ether, coconut oil fatty acid diethanolamide, dehydrated sorbitan monostearate, polyoxyethylene sorbitan monolaurate, dodecyl dimethyl benzyl ammonium chloride, and hexadecyl trimethyl ammonium bromide.

4. The cleaning agent according to claim 1, characterized in that, The pH value of the cleaning agent is 9-14.

5. The cleaning agent according to claim 1, characterized in that, The temperature for ultrasonic cleaning is 30-70℃.

6. The cleaning agent according to claim 1, characterized in that, The ultrasonic cleaning time is 30-60 minutes.

7. The cleaning agent according to claim 1, characterized in that, The polyester is either a semi-dull polyester melt or a bright polyester melt.

8. The cleaning agent according to claim 2, characterized in that, When there are two or more alkali agents, the weight percentage of each component is 1-8%, and the total percentage does not exceed 10%.

9. The cleaning agent according to claim 3, characterized in that, When there are two or more surfactants, the weight percentage of each component is 1-10%, and the total percentage does not exceed 15%.

10. The cleaning agent according to claim 1, characterized in that, The ultrasonic cleaner has a power of 100-500W and an ultrasonic frequency of 20-80kHz.

Images