Flax roving scouring and bleaching process

Abstract

The invention provides a flax roving scouring and bleaching process which comprises the following steps: 1, loading flax roving into a creel with a Teflon coating in a loose uniform winding manner, and controlling the total yarn loading amount to be 75 + / -5% of the effective volume of a main scouring and bleaching pot; 2, soft water is injected into a saucepan according to the liquid ratio of 1: 10-1: 15, the temperature is increased to 65-75 DEG C, a nonionic penetrant is added, the creel in the step 1 is hung into the saucepan after operation is conducted for 5 minutes, heat preservation operation is conducted for 25-35 minutes in a positive and negative circulation alternating mode, and after waste liquid is discharged, normal-temperature soft water is used for washing twice in an overflow mode, and washing is conducted for 10 minutes each time; 3, formic acid and a metal ion chelating agent are added into a main pot, water is added till the liquid ratio is 1: 12, a circulating pump is started, the temperature is increased to 50-55 DEG C, the washed creel is put into the main pot, the temperature is kept, the stirring reaction is conducted for 20-30 minutes, the pH value is monitored and maintained to be 3.0-3.5 in the process, and after pickling is completed, waste liquid is pumped into a neutralization pool to be treated after being filtered through a stainless steel filter screen.

Description

A flax roving scouring and bleaching process Technical Field

[0001] This invention relates to a method for scouring and bleaching flax roving, specifically, to a process for scouring and bleaching flax roving. Background Technology

[0002] Scouring and bleaching of flax roving are essential pretreatment steps in the wet spinning process of flax. Their purpose is to remove natural byproducts such as pectin, lignin, and hemicellulose from glued flax fibers using chemical methods, while imparting a certain degree of whiteness and excellent capillary effect to the fibers. This improves the spinnability of the fibers and enhances the evenness, strength, and surface smoothness of the final yarn. Currently, the commonly used scouring and bleaching processes in the industry still have some problems: strong inorganic acids such as sulfuric acid are commonly used for acid washing, which are highly corrosive and easily cause localized acid damage to the fibers; this can easily lead to localized fiber burns and a decrease in polymerization degree, resulting in a high rate of loss in breaking strength. The lack of clear process standardization leads to inconsistent treatment levels at different locations within the scouring pan and between the inner and outer layers of the yarn, resulting in significant differences in whiteness and hand feel, affecting the uniformity of subsequent spinning.

[0003] Therefore, there is an urgent need for a flax roving scouring and bleaching process to achieve stable production with high quality, high efficiency, low damage, and environmental friendliness. Summary of the Invention

[0004] Design a scouring and bleaching process for flax roving to achieve stable production with high quality, high efficiency, low damage, and environmental friendliness.

[0005] A flax roving scouring and bleaching process includes the following steps: Step 1: Load the flax roving into a Teflon-coated yarn rack using a loose and uniform winding method. The total amount of yarn loaded should be controlled to 75% ± 5% of the effective volume of the main scouring and bleaching pot. Step 2: Pour soft water into the scouring pot at a liquid ratio of 1:10 to 1:15, raise the temperature to 65℃ to 75℃, add a non-ionic penetrant, and run for 5 minutes. Then, lower the yarn rack from Step 1 into the pot and maintain the temperature for 25 to 35 minutes using alternating forward and reverse circulation. After draining the waste liquid, rinse twice with room temperature soft water using an overflow method. Step 3: Add formic acid and metal ion chelating agent to the main pot, add water to a liquid ratio of 1:12, start the circulation pump, heat to 50℃~55℃, put in the washed yarn rack, keep warm and stir for 20~30 minutes, monitor the pH value during the process and maintain it at 3.0~3.5. After the acid washing is completed, the waste liquid is filtered through a stainless steel filter and then pumped into the neutralization tank for treatment; Step 4: Prepare the working mother liquor in the auxiliary tank, and accurately add the following per liter of working liquor: 2.0~2.5g of caustic soda (NaOH), 1.5~2.0g of soda ash (Na2CO3), 0.8~1.0g of penetrant JFC, 1.0~1.5g of stabilizer, 3.0~4.0g of sodium silicate (modulus 2.4), 5.0~6.0g of hydrogen peroxide (50%), and 0.3~0.5g of condensing agent DTPMPA (diethylenetriaminepentamethylenephosphonic acid). g; Inject the mother liquor into the main pot, add water to a liquor ratio of 1:10, heat to 90℃±2℃, and circulate at this temperature for 5 minutes to achieve equilibrium. Then, cool down to 72℃±2℃ at a rate of 1.5℃ / minute, place the yarn on the yarn rack, and keep warm for bleaching for 50~60 minutes. After bleaching, the discharged bleaching liquor is discharged into the wastewater treatment system after recovering residual heat through a heat exchanger. Step 5: Use a countercurrent rinsing system to wash the oxygen-bleached roving: the first stage is a 60℃ hot water wash for 10 minutes, the second stage is a 40℃ warm water wash for 10 minutes, and the third stage is a room temperature soft water wash for 10 minutes. Step 6: Remove the yarn rack, dehydrate it using a centrifugal dewatering machine, and then send it to a constant temperature and humidity equilibrium room for humidity conditioning. Once the internal and external humidity of the fiber is balanced, it can be used for wet spinning fine yarn process.

[0006] Preferably, in step one, "controlling the total amount of yarn loaded to 75% ± 5% of the effective volume of the main boiling and rinsing pot" involves using an electronic weighing system to weigh the yarn on each yarn rack and calculating the total volume percentage using a PLC control system, with the loading density controlled between 0.38 and 0.42 g / cm³. 3 between.

[0007] Preferably, soft water is used in both steps two and five.

[0008] Preferably, the acid used in the "catalytic acid washing" in step three is formic acid, a volatile organic acid.

[0009] Preferably, the "stabilizer" in step four is an organophosphate stabilizer, which is used in combination with sodium silicate.

[0010] Preferably, in step four, the temperature is reduced to 72℃±2℃ before the yarn is placed on the yarn rack, using a "preheating balance" method of first heating and then cooling.

[0011] Preferably, the specific process of the "three-stage countercurrent rinsing system" in step five is as follows: the final stage of cleaning and washing water is added to the third stage water washing tank, the water from the third stage overflows to the second stage water washing tank as washing water, the water from the second stage overflows to the first stage water washing tank for the first rinse, and finally only the high-concentration wastewater from the first stage is discharged and treated.

[0012] Preferably, the "humidification treatment" conditions in step six are: temperature 25℃±2℃, relative humidity 65%±5%, and equilibration time of not less than 4 hours.

[0013] Preferably, the process flow integrates a distributed control system (DCS), which monitors and automatically adjusts the temperature, pH value, liquid level, chemical injection volume and reaction time in steps two, three, four and five in real time, and all process parameters are recorded and stored.

[0014] The beneficial effects of this invention are as follows: This invention provides a scouring and bleaching process for flax roving. This process combines real-time monitoring and automatic adjustment with a distributed control system (DCS), reducing human error and ensuring process reproducibility, thus minimizing the fluctuation range of core quality indicators for each batch of products. Mild formic acid is used instead of highly corrosive sulfuric acid, and a chelating agent is added to pre-remove impurity ions such as iron and copper that would catalyze the excessive decomposition of hydrogen peroxide. In the oxygen bleaching stage, the bleaching liquor is first raised to a high temperature and then programmed to cool down to the optimal reaction temperature before feeding the fibers, avoiding thermal shock. This ensures uniform and smooth circulation of the scouring and bleaching liquor among the yarns. Combined with alternating forward and reverse circulation stirring during the process and precise temperature field control by the DCS, the chemical concentration and temperature distribution within the scouring pot are uniform. The use of a three-stage countercurrent rinsing system increases the reuse rate of washing water. Detailed Implementation

[0015] To make the technical solution of the present invention easier to understand, specific embodiments are now used to clearly and completely describe the technical solution of the present invention.

[0016] Example 1: A scouring and bleaching process for flax roving, the specific steps of which are as follows: Step 1: Load the flax roving into a Teflon-coated yarn rack in a loose and uniform winding manner. The total amount of yarn loaded is controlled to be 75% ± 5% of the effective volume of the main scouring and bleaching pot to ensure that the scouring and bleaching liquid can circulate fully and evenly between the yarns; Step 2: Pour soft water into the scouring pot at a liquid ratio of 1:10 to 1:15, heat to 65℃ to 75℃, add a non-ionic penetrant, and after running for 5 minutes, suspend the yarn rack from Step 1 into the pot. Keep warm for 25 to 35 minutes by alternating forward and reverse circulation. After draining the waste liquid, use overflow... The first step involves rinsing the yarn twice with room temperature soft water for 10 minutes each time. The second step involves adding formic acid and a metal ion chelating agent to the main pot, adding water to a liquid ratio of 1:12, starting the circulation pump, and heating to 50℃~55℃. The washed yarn rack is then added, and the mixture is kept warm and stirred for 20~30 minutes. The pH value is monitored and maintained at 3.0~3.5 throughout the process. After acid washing, the waste liquid is filtered through a stainless steel filter and then pumped into a neutralization tank for treatment. The third step involves preparing the working mother liquor in the auxiliary tank, precisely adding the following per liter of working liquor: 2.0~2.5g of caustic soda (NaOH) and 1.5~2.0g of soda ash (Na2CO3). g, penetrant JFC 0.8~1.0 g, stabilizer 1.0~1.5 g, sodium silicate (modulus 2.4) 3.0~4.0 g, hydrogen peroxide (50%) 5.0~6.0 g, fusion agent DTPMPA (diethylenetriaminepentamethylenephosphonic acid) 0.3~0.5 g. g; Inject the mother liquor into the main pot, add water to a liquor ratio of 1:10, heat to 90℃±2℃, and circulate at this temperature for 5 minutes to achieve equilibrium. Then, cool down to 72℃±2℃ at a rate of 1.5℃ / minute, place the yarn on the yarn rack, and keep warm for bleaching for 50~60 minutes. After bleaching, the discharged bleaching liquor is discharged into the wastewater treatment system after recovering residual heat through a heat exchanger. Step 5: Use a countercurrent rinsing system to wash the oxygen-bleached roving: the first stage is a 60℃ hot water wash for 10 minutes, the second stage is a 40℃ warm water wash for 10 minutes, and the third stage is a room temperature soft water wash for 10 minutes to reduce water consumption. Step 6: Remove the yarn rack, dehydrate it using a centrifugal dewatering machine, and then send it to a constant temperature and humidity equilibrium room for humidification treatment. Once the internal and external humidity of the fiber is balanced, it can be used for the wet spinning fine yarn process.

[0017] In step one, "the total amount of yarn loaded is controlled to be 75% ± 5% of the effective volume of the main boiling and rinsing pot." An electronic weighing system is used to weigh the yarn on each yarn rack, and a PLC control system calculates the total volume percentage to ensure consistency in the amount of material fed into each batch. The loading density is controlled between 0.38 and 0.42 g / cm³. 3 between.

[0018] In both steps two and five, "soft water" is used to prevent calcium and magnesium ions from reacting with the bleaching aid to form insoluble flocs.

[0019] The acid used in the "catalytic acid washing" in step three is formic acid, a volatile organic acid; the added metal ion chelating agent can effectively complex catalytic metal ions such as iron and copper.

[0020] The "stabilizer" in step four is an organophosphate stabilizer. When used in combination with sodium silicate, it can form a more stable colloidal system. Its stabilization efficiency for hydrogen peroxide is higher than that of sodium silicate alone, allowing bleaching to be carried out at higher alkalinity and temperature.

[0021] In step four, the temperature is lowered to 72℃±2℃ before the yarn is placed on the yarn rack. The "preheating balance" method of first raising the temperature and then lowering it is used to ensure that the fiber enters the bleaching stage under mild conditions.

[0022] The specific process of the "three-stage countercurrent rinsing system" in step five is as follows: the final stage of cleaning and washing water is added to the third stage water washing tank, the water from the third stage overflows to the second stage water washing tank as washing water, the water from the second stage overflows to the first stage water washing tank for the first rinse, and finally only the high-concentration wastewater from the first stage is discharged and treated.

[0023] The conditions for the "humidification treatment" in step six are: temperature 25℃±2℃, relative humidity 65%±5%, and equilibration time of not less than 4 hours.

[0024] The process flow integrates a distributed control system (DCS), which monitors and automatically adjusts the temperature, pH value, liquid level, chemical injection volume, and reaction time in steps two, three, four, and five in real time. All process parameters are recorded and stored.

[0025] The final flax roving processed by this process has the following quality indicators: whiteness ≥75%, breaking strength loss rate ≤15%, weight loss rate controlled within the range of 12%~18%, residual wax content ≤0.3%, and capillary effect ≥10 cm.

[0026] Example 2: In using this method: The spun flax roving is wound onto a stainless steel yarn rack. Treated soft water is poured into a boiling pot. Water is added until the set level is reached, and indirect steam heating is activated. A non-ionic penetrant is added. The main circulation pump is turned on, and the circulation is repeated in both directions for 5 minutes to ensure uniform dispersion of the auxiliaries. The yarn rack is then lowered into the pot, and the alternating circulation continues for 30 minutes. After treatment, the wastewater in the pot is drained. Subsequently, the yarn in the pot is quickly rinsed twice with room temperature soft water via overflow to remove most suspended impurities.

[0027] After draining the washing liquid, close the drain valve. Add formic acid to the main tank using a metering pump. Simultaneously, add disodium EDTA, a metal ion chelating agent. Add soft water to the total volume, turn on the circulation pump and heating system, and place the yarn rack into the tank to begin the timed pickling process. After pickling, pump all the waste liquid into an intermediate storage tank, and then use a basket filter with a stainless steel mesh to intercept any loose short fiber debris and other solid impurities. The filtered acidic waste liquid is then pumped into the neutralization and equalization tank of the factory's wastewater treatment plant for centralized treatment.

[0028] In a separate mixing tank equipped with a stirrer, an appropriate amount of warm water is first added. While stirring, stabilizer, sodium silicate, soda ash, caustic soda flakes, penetrant, and chelating agent are added sequentially, ensuring each is dissolved before adding the next. Finally, hydrogen peroxide is slowly added, followed by soft water and stirring for 20 minutes to prepare a uniform bleaching mother liquor. The prepared mother liquor is then pumped into the main pot, which has already been drained of pickling liquid. Soft water is added to heat and circulate the bleaching liquor for 5 minutes. Subsequently, the control system activates the temperature-reducing module. After the temperature stabilizes, the yarn rack is lowered into the main pot. Under constant temperature conditions, heat preservation bleaching is performed. During bleaching, the main circulation pump operates continuously and automatically switches flow direction every 20 minutes. After bleaching, the bleaching residue is exchanged with the cold soft water that will soon enter the boiling pot to recover residual heat. The cooled residue then enters the oxidation and degradation section of the wastewater treatment system.

[0029] A three-stage counter-current rinsing system is used. The yarn racks are hoisted from the boiling pot and sequentially enter the first-stage hot water rinsing tank, where they are soaked and circulated for 10 minutes. This tank has the highest wastewater concentration and is periodically discharged to the treatment plant. Next, the yarn racks enter the second-stage warm water rinsing tank, where they are soaked and circulated for 10 minutes. The replenishment water for this tank comes from the relatively clean water overflowing from the third stage. Finally, the yarn racks enter the third-stage cold water rinsing tank, where they are soaked and circulated with room-temperature soft water for 10 minutes. This tank is continuously replenished with fresh soft water, and its overflow water is used as the washing water for the second stage.

[0030] After washing, the yarn frames are suspended in a centrifugal dewatering machine for 3 minutes. Then, the yarn frames are transferred to a constant temperature and humidity balancing room and conditioned for at least 4 hours to ensure sufficient balance between the internal and external humidity of the fibers and to eliminate internal stress. Finally, quality inspection is conducted to ensure that there is no color difference between the inner and outer layers of the yarn and between the yarn frames, and that the yarn has a soft and uniform feel.

[0031] It should be noted that the embodiments described herein are only some embodiments of the present invention, and not all implementations of the present invention. These embodiments are merely illustrative and are intended only to provide a more intuitive and clear way to understand the content of the present invention, not to limit the technical solutions described herein. All other implementation methods that can be conceived by those skilled in the art without creative effort, as well as other simple substitutions and variations of the technical solutions of the present invention, without departing from the concept of the present invention, are within the protection scope of the present invention.

Claims

1. A scouring and bleaching process for flax roving, characterized in that, The specific steps are as follows: Step 1: Load the flax roving into the Teflon-coated yarn frame using a loose and even winding method. The total amount of yarn loaded should be controlled to 75% ± 5% of the effective volume of the main boiling and rinsing pot. Step 2: Pour soft water into the boiling pot at a liquid ratio of 1:10 to 1:15, raise the temperature to 65℃ to 75℃, add a non-ionic penetrant, and run for 5 minutes. Then, lower the yarn frame from Step 1 into the pot and maintain the temperature for 25 to 35 minutes using alternating forward and reverse circulation. After draining the waste liquid, rinse with room temperature soft water using an overflow method. Step 3: Add formic acid and metal ion chelating agent to the main pot, add water to a liquid ratio of 1:12, start the circulation pump, heat to 50℃~55℃, put in the washed yarn rack, keep warm and stir for 20~30 minutes, monitor the pH value during the process and maintain it at 3.0~3.

5. After acid washing, the waste liquid is filtered through a stainless steel filter and then pumped into the neutralization tank for treatment; Step 4: Prepare the working mother liquor in the auxiliary tank, and accurately add the following per liter of working liquor: 2.0~2.5 g of caustic soda (NaOH), 1.5~2.0 g of soda ash (Na2CO3), 0.8~1.0 g of penetrant JFC, 1.0~1.5 g of stabilizer, 3.0~4.0 g of sodium silicate (modulus 2.4), 5.0~6.0 g of hydrogen peroxide (50%), and 0.3~0.5 g of condensing agent DTPMPA (diethylenetriaminepentamethylenephosphonic acid). g; Inject the mother liquor into the main pot, add water to a liquor ratio of 1:10, heat to 90℃±2℃, and circulate at this temperature for 5 minutes to achieve equilibrium. Then, cool down to 72℃±2℃ at a rate of 1.5℃ / minute, place the yarn on the yarn rack, and keep warm for bleaching for 50~60 minutes. After bleaching, the discharged bleaching liquor is discharged into the wastewater treatment system after recovering residual heat through a heat exchanger. Step 5: Use a countercurrent rinsing system to wash the oxygen-bleached roving: the first stage is a 60℃ hot water wash for 10 minutes, the second stage is a 40℃ warm water wash for 10 minutes, and the third stage is a room temperature soft water wash for 10 minutes. Step 6: Remove the yarn rack, dehydrate it using a centrifugal dewatering machine, and then send it to a constant temperature and humidity equilibrium room for humidity conditioning. Once the internal and external humidity of the fiber is balanced, it can be used for wet spinning fine yarn process.

2. The scouring and bleaching process for flax roving as described in claim 1, characterized in that: In step one, "the total amount of yarn loaded is controlled to be 75% ± 5% of the effective volume of the main boiling and rinsing pot." An electronic weighing system is used to weigh the yarn on each yarn rack, and the total volume percentage is calculated using a PLC control system. The loading density is controlled between 0.38 and 0.42 g / cm³. 3 between.

3. The scouring and bleaching process for flax roving as described in claim 1, characterized in that: Both steps two and five use "soft water".

4. The scouring and bleaching process for flax roving as described in claim 1, characterized in that: The acid used in the "catalytic pickling" step three is formic acid, a volatile organic acid.

5. The scouring and bleaching process for flax roving as described in claim 1, characterized in that: The "stabilizer" in step four is an organophosphate stabilizer, which is used in combination with sodium silicate.

6. The scouring and bleaching process for flax roving as described in claim 1, characterized in that: In step four, the temperature is lowered to 72℃±2℃ before being placed into the yarn rack, using a "preheating balance" method of first raising the temperature and then lowering it.

7. The scouring and bleaching process for flax roving as described in claim 1, characterized in that: The specific process of the "three-stage countercurrent rinsing system" in step five is as follows: the final stage of cleaning and washing water is added to the third stage water washing tank, the water from the third stage overflows to the second stage water washing tank as washing water, the water from the second stage overflows to the first stage water washing tank for the first rinse, and finally only the high-concentration wastewater from the first stage is discharged and treated.

8. The scouring and bleaching process for flax roving as described in claim 1, characterized in that: The conditions for "humidification treatment" in step six are: temperature 25℃±2℃, relative humidity 65%±5%, and equilibration time of not less than 4 hours.

9. The scouring and bleaching process for flax roving as described in claim 1, characterized in that: The process flow integrates a distributed control system (DCS), which monitors and automatically adjusts the temperature, pH value, liquid level, chemical injection volume, and reaction time in steps two, three, four, and five in real time. All process parameters are recorded and stored.