WO2022095053A1 - Method for supercritical mixed-fluid flash-explosion treatment of natural fiber and product thereof - Google Patents

Abstract

Provided is a method for supercritical mixed-fluid flash-explosion treatment of a natural fiber and product thereof, including the following steps: filling a natural fiber or natural fiber product in a predetermined form in a flash-explosion treatment unit (10), and transferring the flash-explosion treatment unit (10) into a flash-explosion treatment apparatus; connecting the flash-explosion treatment apparatus to a non-CO2 medium apparatus, and introducing a non-CO2 medium into the interior of the flash-explosion treatment apparatus; connecting the flash-explosion treatment apparatus to the CO2 medium apparatus, and charging CO2 medium to the interior of the flash-explosion treatment apparatus, while simultaneously heating and increasing the temperature; when the modified treatment temperature and modified treatment pressure of the mixed fluid reach a preset value, sequentially treating in the order of fluid circulation and then fluid stasis; rapidly releasing the pressure or instantaneously releasing the pressure of the flash-explosion apparatus within the flash-explosion time, and causing the pressure inside the flash-explosion treatment apparatus to be reduced to atmospheric pressure, enabling flash-explosion treatment of a treatment sample. The method enables modified treatment of natural fiber or product thereof, improving dyeing performance in supercritical CO2 fluids.

Description

A kind of supercritical mixed fluid flash explosion treatment method of natural fiber and its products technical field

The invention relates to the technical field of textile dyeing and finishing technology, more particularly, to a supercritical mixed fluid flash explosion treatment method for natural fibers and their products.

Background technique

At present, the contradiction between my country's economic and social development and resource and environmental constraints has become increasingly prominent, and environmental protection is facing severe challenges. More and more traditional printing and dyeing industries are facing the crisis of being eliminated by competition and abandoned by the market because of the large amount of discharge and pollution. Therefore, it is urgent to find a green, safe and environment-friendly dyeing method.

Carbon dioxide is a colorless, odorless, and easy-to-obtain inert gas in its natural state. Its molecule is linear, and two oxygen atoms are symmetrically distributed on both sides of the carbon atom. It is a polar molecule. And because its critical temperature and critical pressure are relatively mild, at 31.1°C and 7.38MPa, it has become the most widely used dyeing medium in supercritical fluid dyeing; supercritical CO ₂ fluid dyeing technology uses CO ₂ fluid as dyeing medium, which can be completely replaced Moreover, the process is short, the operation is convenient, and no industrial waste water pollution is generated, which completely solves the problems caused by the environmental pollution caused by textile processing.

So far, supercritical CO ₂ fluid dyeing technology using disperse dyes in synthetic fibers such as polyester and polyamide has reached the commercial production demand. However, since the natural fibers traditionally used for dyeing contain hydroxyl and amino groups and are highly polar, direct dyes, reactive dyes, acid dyes and other polar dyes are generally used for dyeing in the dyeing process. However, since supercritical _CO2 is non-polar and has low solubility or insoluble to these polar dyes, the amount of dyes carried by the supercritical _CO2 fluid during dyeing is low, and the color depth after dyeing is extremely low, which has no commercial value. . And disperse dyes dissolved in supercritical CO ₂ fluid have small molecular weight, simple molecular structure, and lack of active functional groups, so that disperse dyes have less affinity for natural fibers, and thus cannot truly dye natural fibers. Therefore, natural fiber dyeing has always been a major difficulty in supercritical CO ₂ fluid dyeing.

SUMMARY OF THE INVENTION

The invention provides a supercritical mixed fluid flash explosion treatment method for natural fibers and their products, which can effectively realize the modification treatment of natural fibers or their products, improve their dyeing performance in supercritical CO ₂ fluid, and solve the problem of traditional water bath. In dyeing, high energy consumption, high pollution, high emission, and difficulty in recycling and disposing of dyestuffs.

According to one aspect of the present invention, there is provided a supercritical mixed fluid flash explosion treatment method of natural fibers and products thereof, comprising the following steps:

Filling the natural fiber or natural fiber product in the flash-detonation treatment unit according to a predetermined form, and transferring the flash-detonation treatment unit into the flash-detonation treatment device;

Connect the flash explosion treatment device to the non-CO ₂ medium device, under standard atmospheric pressure, pass the non-CO ₂ medium into the flash explosion treatment device, and disconnect the connection with the non-CO ₂ medium device after the end;

Connect the flash-explosion treatment device to the CO ₂ medium device, fill the CO ₂ medium into the flash-explosive treatment device, and heat up at the same time;

When the modification treatment temperature and modification treatment pressure of the mixed fluid inside the flash-detonation treatment device reach the preset values, the treatment sequence of fluid circulation and fluid static treatment is carried out for a predetermined modification treatment time, so that the fluid enters uniformly and fully Distributed in the inner phase of fibers;

Control the pressure and/or temperature of the separation and recovery unit, and perform flash explosion treatment with different temperature differences and/or different pressure differences;

The flash-explosion treatment device is quickly or instantaneously depressurized within the flash-explosion time, and the flash-explosion treatment is performed on natural fibers or natural fiber products;

Turn on the gas recovery pump of the separation and recovery unit to separate and recover different media, reduce the pressure in the flash explosion system to atmospheric pressure, and then take out the treated samples to complete the flash explosion treatment of dry natural fibers or natural fiber products.

Further, the natural fibers are one or more of cotton, hemp, silk, and wool, but are not limited to.

Further, the natural fiber product is one or more of fibers, yarns, and fabrics, but not limited to.

Further, when the sample is fiber, the fluffy fibers are extruded neatly and uniformly layer by layer by the action of mechanical external force, so that they can be flatly filled in the flash explosion treatment unit according to a certain tightness;

When the sample is yarn, use mechanical external force to process the yarn so that it can be wound neatly and evenly at a certain interval, so that it can be evenly and evenly wound in the flash treatment unit;

When the sample is a fabric, the flat fabric is wound neatly and evenly by mechanical external force, so that it can be evenly and evenly wound in the flash explosion treatment unit.

Further, the flash explosion treatment unit is made of a non-heat-causing surface material covered with a surface material, and a plurality of hollow holes are distributed around the flash explosion treatment unit and on the central hollow tube.

Further, the flash explosion treatment unit is made of polytetrafluoroethylene material.

Further, the non-CO ₂ medium is one or more of saturated steam, superheated steam, methanol, ethanol, acetone, acid and alkali.

Further, the modification treatment pressure is 0-30MPa.

Further, the modification treatment temperature is 90-180°C.

Further, the modification treatment time is 0-60min.

Further, the time ratio of the fluid circulation to the static state is 1:5-10:1.

Further, the flash explosion time is 0-40s.

Further, according to the required number of flash explosions, the natural fibers or natural fiber products are subjected to repeated operations for many times.

Further, the temperature of the separation and recovery unit is 0-180°C, and the pressure is 0-28MPa.

In the present invention, natural fibers or natural fiber products are packed tightly in layers in a special flash explosion treatment unit by means of mechanical compaction, so that natural fibers or natural fiber products are evenly distributed in the device; through a certain non-CO ₂ The treatment of the medium such as saturated steam, and the critical state of CO ₂ fluid; The degree of molecular freedom is increased, the amorphous region of the fiber is increased, and the dye molecules are more likely to enter the interior of the fiber molecule, improving the dyeing performance of natural fibers or their products in supercritical CO ₂ fluid. In addition, the method has the advantages of convenient operation, simple process, short process flow, no waste water pollution and high treatment efficiency.

The supercritical mixed fluid flash explosion treatment method for natural fibers and their products provided by the invention can effectively realize the modification treatment of natural fibers or their products, improve their dyeing properties in supercritical CO ₂ fluid, and solve the problem of traditional water bath. In dyeing, high energy consumption, high pollution, high emission, and difficulty in recycling and disposing of dyestuffs. At the same time, the invention is simple and convenient to operate, and can effectively realize the processing of natural fibers, improve the dyeing performance of the natural fibers without changing the excellent properties of the natural fibers.

Description of drawings

The accompanying drawings are used to provide a further understanding of the present invention, and constitute a part of the specification, and are used to explain the present invention together with the embodiments of the present invention, and do not constitute a limitation to the present invention. In the attached image:

Fig. 1 is the schematic diagram of the supercritical mixed fluid flash explosion treatment method of natural fiber and its product;

FIG. 2 is a cross-sectional view of a flash explosion processing unit.

In the figure: 1. _CO2 storage tank; 2. The first shut-off valve; 3. Condenser; 4. Compression pump; 5. Preheater; 6. The second shut-off valve; 7. Dye dissolving unit; 8. Filtration 9, the third cut-off valve; 10, the flash explosion processing unit; 11, the fourth cut-off valve; 11', the fifth cut-off valve; 12, the circulation pump; 12', the gas recovery pump; 13, the sixth cut-off valve; 14. Seventh stop valve; 15. Fine-tuning valve; 16. Thermometer; 17. Pressure gauge; 18. Separation kettle; 19. Dye thermometer; 20. Dye pressure gauge; 21. Purifier; 22, CO ₂ fluid and dye inlet ; 23, non-CO ₂ medium inlet and outlet shut-off valve; 24, fluid outlet; 25, quick opening structure; 26, flash explosion treatment unit sealing cover; 27, non-CO ₂ medium inlet.

Detailed ways

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

The fibers used in the examples of the present invention are cotton fibers, dry fibers that have not been treated before dyeing; the dye used is supercritical CO ₂ special reactive disperse yellow SCF-AY02, which is a laboratory product of the inventor.

Referring to Figures 1 and 2, the supercritical mixed fluid flash explosion treatment method of natural fibers and their products adopted in the embodiment of the present invention is carried out in a flash explosion treatment device.

The bottom of the flash treatment unit 10 is provided with a CO ₂ fluid and a dye inlet 22, and the top is provided with a flash treatment unit sealing cover 26. The top of the flash treatment unit sealing cover 26 is also connected with a thermometer 16 and a pressure gauge 17, which are respectively used for measuring flash. The temperature and pressure values in the explosion treatment device; two quick opening structures 25 are provided on both sides of the sealing cover 26 of the explosion treatment unit for rapid pressure relief. The top of the flash explosion treatment unit 10 is provided with a non-CO ₂ medium inlet 27 and a fluid outlet 24, and the bottom is provided with a non-CO ₂ medium inlet and outlet shut-off valve 23,

The dry cotton fiber is mechanically compressed, and filled with a certain tightness in the flash processing unit 10, and then the flash processing unit is sealed with the flash processing unit sealing cover 26, and the flash processing unit sealing cover is closed. 26. Close the third shut-off valve 9 and the seventh shut-off valve 14 in the entire flash-explosion treatment device, open the non-CO ₂ medium inlet and outlet shut-off valve 23, and introduce a certain amount of non-CO ₂ medium into the flash-detonation treatment unit, which can be saturated steam , one or more of superheated steam, methanol, ethanol, acetone and other organic solvents, acids and alkalis, and adjust the opening and closing degree of the fifth shut-off valve 11' to flush CO ₂ into the flash explosion treatment device; keep the flash explosion The certain pressure in the treatment device is 0-10Mpa, and the fibers are processed for 0-30min; the system parameters such as temperature and pressure of the separation and recovery unit are controlled to predetermined values of 0-180℃, 0-28MPa, respectively. Then quickly open the medium outlet stop valve to release the pressure, and ensure that the pressure release time is 0-40s. Open the gas recovery pump of the separation and recovery system to separate and recover different treatment media, reduce the pressure in the flash explosion system to atmospheric pressure, and then take out the sample to complete the flash explosion treatment of dry natural fibers or natural fiber products.

After the treatment, close the non-CO ₂ medium and the CO ₂ medium inlet shut-off valve, close the fourth shut-off valve 11 and the fifth shut-off valve 11', open the third shut-off valve 9 of the dye dissolving unit, and use the flash explosion treatment unit 10 as the The dyeing unit is dyed in the flash-explosion processing unit 10, and the dissolved dye and CO ₂ fluid are introduced into the flash-explosive processing unit 10, and according to the predetermined dyeing process flow and parameters, start the CO ₂ storage tank 1, the condenser 3 The pressurization system including the pressurizing pump 4 and the preheater 5 pressurizes the dyeing circulation system and preheats and warms the fluid, opens the first cut-off valve 2 and the second cut-off valve 6, and makes the dye in the dye dissolving unit 7 The dye is fully dissolved; the dye dissolving unit 7 is connected with a dye thermometer 19 and a dye pressure gauge 20 . When the temperature of the dyeing circulation system reaches a predetermined temperature such as 130°C and the pressure reaches a preset value such as 20Mpa, the pressurizing pump 4 stops the pump, closes the second shut-off valve 6, turns on the circulating pump 12 in the dyeing circulation loop, and opens the sixth shut-off valve 13. The dissolved dye is filtered through the filter 8 and circulated with the fluid, and fully dyed with the sample to be dyed. The ratio of fluid circulation time to fluid static time during dyeing was 10:1. Under static and circulating conditions, the dissolved dyes fully contact with the pure cotton staple fibers in the dyeing unit through their own molecular thermal motion and fluid mass transfer, and complete the processes of adsorption, dyeing, diffusion and fixation.

After the heat preservation and pressure dyeing is completed, the fine-tuning valve 15 is opened to release the pressure of the system, and the dye and fluid in the dyeing circulation system are removed by the separation and recovery system composed of the gas recovery pump 12', the separation kettle 18, the purifier 21, the condenser 3, etc. separation and recovery.

After the separation and recovery of the fluid, repeat the above operation again to clean the fibers online. . After cleaning, the pressure relief system is used to separate and recover the gas and dye, and the pressure in the dyeing unit can reach atmospheric pressure. Finally, the fluid flash treatment unit 10 is turned on, and the dyed fibers are taken out from the device.

With reference to the above-mentioned processing steps and technology, the cotton fiber is dyed with reactive disperse dyes, and its analysis test and its results are as follows:

1. Determination of color depth value of fiber surface

The surface color depth value of fiber samples treated by supercritical CO ₂ fluid flash explosion was measured by Hunterlab Ultrascan PRO spectrophotometer. During the test, choose D ₆₅ light source, 10° viewing angle, and uniformly mix the fibers for sample preparation. 8 points are randomly tested for each sample, and the arithmetic mean is finally calculated.

Among them, i represents the i-th test point (i=1, 2, 3, .., n; here n=8);

Represents the surface color depth value of the i-th test point at the maximum absorption wavelength;

Represents the arithmetic mean of the surface color depth values of n test points at the maximum absorption, and the calculation method is shown in formula (1).

2. Determination of fiber water retention rate

According to the textile industry standard FZ/T 50040-2018. The water retention rate of short cotton fibers was tested to test whether the hydrophilic properties of the fibers were changed after treatment. The specific steps are:

(1) The cotton fiber after the fluid flash explosion is opened, so that the fiber crimp bundle is opened, and the whole is in a fluffy state, ready for use.

(2) Then take 2g of flash-exploded fibers under different conditions, open them, and put them in the same environment to balance for 24 hours to ensure that the moisture regain of the fibers is consistent and the moisture balance is achieved.

(3) Accurately weigh m ₀ (2.00±0.01) g of the fiber after the humidity adjustment and balance, and record it as the fiber mass m ₀ ; put the fiber into the prepared metal cylinder, and the cylinder specification is height (80 ±1)mm, diameter (50±1)mm, one end sealed.

(4) Take a 2000mL beaker, add distilled water to the scale, measure the water temperature, and keep the water temperature constant at (20±2)°C.

(5) Immerse the metal cylinder and the fibers in it in a beaker of distilled water, and start timing when the sample is completely submerged. After 10 minutes, pick up the immersed sample with stainless steel tweezers. When taking out the sample, be careful not to squeeze the fiber mass too much.

(6) Put the sample taken out on the draining device, drain the excess liquid in a constant temperature and constant pressure environment, and the draining time is (30±1) min. The drained fibers were placed in a glass dish, and the drained fibers were weighed with an electronic balance and recorded as m ₁ , accurate to 0.001 g. Work as gently and carefully as possible to prevent unnecessary moisture loss.

(7) After each test, use a dropper to refill the distilled water in the beaker to the mark, and keep the volume and temperature of the fiber water soaked each time consistent. Repeat the above steps to measure each sample and record the exact result.

(8) Substitute the mass m ₀ before fiber infiltration and the mass m ₁ after fiber infiltration and draining obtained in the above experimental steps into the calculation formula (3-1), and the water retention rate can be obtained.

In the formula: W: water retention rate; m ₁ : the mass of fibers after soaking and draining, in grams (g); m ₀ refers to the mass of fibers before soaking, in grams (g).

Example 1:

A certain amount of pure cotton fiber is modified, and 1g/L of saturated steam is introduced into the fluid flash treatment unit to seal the system. Start the booster pump to charge quantitative CO ₂ to make the pressure reach 5MPa. At the same time, the inside of the flash explosion treatment device was heated to a predetermined temperature of 130°C. When the temperature and pressure reach the set value, turn on the circulating pump with the ratio of fluid circulation and fluid static treatment time being 5:1, and process for 10min. According to the flash explosion process or requirements, the system parameters of the separation and recovery unit, such as temperature and pressure, are respectively controlled to be 20°C and 0.1MPa. Then open the pressure relief valve to quickly release the pressure. The pressure relief time, that is, the flash explosion time, is 8s, and the entire flash explosion process is processed once.

After the treatment was completed, ₂ g of the fluid-flashed cotton fibers were dyed in supercritical CO fluid. The dyeing process was as follows: the dyeing pressure was 20 MPa, the dyeing temperature was 120 °C, the dyeing time was 60 min, and the liquor ratio was 1:1000. After dyeing, the online cleaning temperature was 80°C, the pressure was 20MPa, and the total cleaning time was 30min. After cleaning, take out the sample and measure the surface color depth value with a spectrophotometer. Then take 2g of the treated cotton fiber, place it in the water retention rate device, wet the fiber according to the water retention rate measurement steps, then measure the mass m ₁ after it is wetted and drained, and then calculate its water retention rate value according to formula (2). .

After testing, the cotton fiber treated by fluid flash modification in Example 1 had a dyed surface depth value (K/S) of 1.04, and the water retention rate of the treated sample was 79.0%.

Parameter table of cotton fiber dyeing after flash-explosion modification treatment in Table 1-1 Example 1

Comparative Example 1:

This comparative example provides a blank comparative example, using untreated cotton fiber for dyeing in supercritical CO ₂ fluid, and the dyeing process is the same as that of Example 1. Then take 2g of the dyed fiber, place it in the water retention rate device, wet the fiber according to the water retention rate measurement steps, then measure the wetted and drained mass m ₁ , and then calculate its water retention rate value according to formula (2). . The surface color depth value (K/S) of dyeing was 0.75, and the water retention rate of the treated sample was 49.2%.

Table 1-2 Parameter table of cotton fiber dyeing after non-flashing modification treatment in Comparative Example 1

During the flash explosion treatment of the mixed fluid, saturated water vapor is applied to the cotton fibers, which will have a certain degree of swelling effect on the fibers, which is conducive to the penetration of water vapor into the fibers. During the instantaneous pressure relief process, the high temperature and high pressure The mixed fluid formed by water vapor and CO ₂ is instantly released in the voids inside the fiber, and the high-speed flow inside the fiber and hot steam causes a certain degree of mechanical bursting in the fiber, destroying the intramolecular hydrogen bond and weakening the intermolecular force. At the same time, the voids in the fibers are increased, and the pore size is increased. It makes it easier for water molecules to penetrate into the interior of the fiber and increase the water absorption performance of the fiber. Therefore, after the water retention rate measurement, the water retention rate of the cotton fiber after the mixed fluid flash explosion treatment is significantly improved, and the water retention rate increased from 49.2% to 79%. .

During the flash-expansion process of cotton fiber in mixed fluid, water vapor and CO ₂ fluid flow inside the fiber, and friction is generated between the unit cells in the cotton fiber molecule, which makes the intramolecular crystalline region split smaller and weakens the hydrogen bond in the fiber. The macromolecular segments in the amorphous region are rearranged, and the fiber accessibility is increased; after the mixed fluid formed by high-pressure and high-heat water vapor and CO ₂ penetrates into the fiber, it is instantly released from the closed pores while the pressure is released, making the cotton The tightly packed structure inside the fiber is effectively loosened, and the inner pore size of the fiber increases; at the same time, the large amount of energy generated by the mixed fluid flash explosion treatment also greatly destroys the intramolecular hydrogen bonds and changes the arrangement of macromolecular segments in the fiber. Therefore, after the mixed fluid flash-explosion treatment, the increase of the amorphous region and the rupture of hydrogen bonds make the dye more easily diffused into the fiber in the supercritical CO ₂ fluid. Therefore, after the mixed fluid flash treatment, the surface color depth value of the fibers increased from 0.75 to 1.04.

Example 2:

This embodiment provides a supercritical mixed fluid flash explosion treatment method, the steps of which are basically the same as those in Embodiment 1, except that the modification treatment temperature is 70°C.

Using the process in Example 2 to treat the cotton fiber, the dyed surface color depth value (K/S) after treatment was 0.64, and the water retention rate of the treated sample was 60.0%.

Parameter table of cotton fiber dyeing after flash-explosion modification treatment in table 2 embodiment 2

Example 3:

This embodiment provides a supercritical mixed fluid flash explosion treatment method, the steps of which are basically the same as those in Embodiment 1, except that the modification treatment temperature is 110°C.

Using the process in Example 3 to treat the cotton fiber, the dyed surface color depth value (K/S) after treatment was 0.93, and the water retention rate of the treated sample was 70.9%.

Parameter table of cotton fiber dyeing after flash-explosion modification treatment in table 3 embodiment 3

It can be seen from Example 1, Example 2 and Example 3 that in the modification treatment temperature range of 70°C to 130°C, with the increase of temperature, the water retention rate gradually increases. Since the increase of temperature makes it easier for water molecules to penetrate into the interior of the fiber and increase the water absorption performance of the fiber, the water retention rate of the fiber after the mixed fluid flash explosion treatment is significantly improved after the measurement of the water retention rate.

Therefore, with the increase of the modification treatment temperature, the water absorption and water retention capacity of the fibers is enhanced, which leads to an increase in the water retention rate of the fibers after the flash explosion treatment. , it can reach 79.0% when it is raised to 130 °C.

When the treatment temperature was from 70 ℃ to 130 ℃, with the increase of the treatment temperature, the color depth value of the cotton fiber surface of the mixed fluid flash explosion increased significantly. As the temperature increases, the kinetic energy of the molecules increases, the friction between the molecular cells of the cotton fiber is more frequently generated by the mixed fluid, and the energy released by the flash explosion is greater. The more obvious the arrangement of molecular segments.

Therefore, after the mixed fluid flash-exploded cotton fibers were dyed in supercritical CO ₂ fluid, as the modification temperature increased, the color depth value of the fiber surface was higher. At 70°C, the surface color depth value of the fiber is 0.64, rising to 110°C, the surface color depth value of the fiber is 0.93, and rising to 130°C, the surface color depth value of the fiber is 1.04.

Example 4:

This embodiment provides a supercritical mixed fluid flash explosion treatment method, the steps of which are basically the same as those in Embodiment 1, except that the modification treatment pressure is 8 MPa.

Using the process in Example 4 to treat the cotton fiber, the dyed surface color depth value (K/S) after treatment was 0.93, and the water retention rate of the treated sample was 80.6%.

Parameter table of cotton fiber dyeing after flash explosion modification treatment in table 4 embodiment 4

Example 5:

This embodiment provides a supercritical mixed fluid flash explosion treatment method, the steps of which are basically the same as those in Embodiment 1, except that the modification treatment pressure is 12 MPa.

Using the process in Example 5 to treat the cotton fiber, the dyed surface color depth value (K/S) after treatment was 0.97, and the water retention rate of the treated sample was 87.6%.

Parameter table of cotton fiber dyeing after flash explosion modification treatment in table 5 embodiment 5

Example 6:

This embodiment provides a supercritical mixed fluid flash explosion treatment method, the steps of which are basically the same as those in embodiment 1, except that the modification treatment pressure is 16 MPa.

Using the process in Example 6 to treat the cotton fiber, the dyed surface color depth value (K/S) after treatment was 0.92, and the water retention rate of the treated sample was 76.3%.

Parameter table of cotton fiber dyeing after flash-explosion modification treatment in table 6 embodiment 6

Example 7:

This embodiment provides a supercritical mixed fluid flash explosion treatment method, the steps of which are basically the same as those in Embodiment 1, except that the modification treatment pressure is 20 MPa.

In Example 7, the cotton fiber was treated by the process, and the dyed surface color depth value (K/S) after the treatment was 1.03, and the water retention rate of the treated sample was 77.4%.

Parameter table of cotton fiber dyeing after flash-explosion modification treatment in table 7 embodiment 7

From Example 1, Example 4, Example 5, Example 6, and Example 7, it can be seen that the water retention rate of the mixed fluid flash-exploded cotton fiber varies slightly from 5 MPa to 20 MPa in the treatment pressure range, basically ranging from 75% to 80%. %between.

In this method, in the process of separation of CO ₂ below 5MPa, CO ₂ and water vapor in the state of subcritical fluid are rapidly converted into gas in the process of rapid decompression. This transformation makes the _CO2 fluid and water vapor originally inside the fiber release huge energy inside the fiber, and the fluid distributed in the gap is instantly flushed out, which increases the pore size of the fiber and increases the micro-gap in the fiber. The pore size makes it easier for water molecules to penetrate into the fiber. The hydrophilic performance of the fiber is improved, and the water retention performance of the mixed fluid flash cotton fiber is improved. The CO ₂ and water vapor higher than 5MPa are separated and recovered into the separation kettle of the system through the internal circulation of the system. The decompression rate of this process is slow, the time is long, and the puffing effect of the fiber is small. Therefore, when the treatment pressure is from 5MPa to 20MPa, the water retention rate of the mixed fluid flash-exploded fibers does not change much.

When the treatment pressure ranges from 5 MPa to 20 MPa, the surface color depth value of the dyed fibers changes little. In this experiment, in the process of separation of CO ₂ below 5MPa, the mixed fluid flashes to make the fiber mechanically bulk up, the intermolecular hydrogen bonds of the fiber are weakened or broken, the pore size of each micropore in the fiber is increased, and the fiber is increased at the same time. The ratio of the amorphous area to the dye molecule makes it easier for the dye molecules to enter the interior of the fiber, promotes the dyeing of the fiber, and makes the reactive disperse yellow SCF-AY02 dye more easily dyed in supercritical CO ₂ fluid. However, the _CO2 and water vapor above 5MPa have less bulking effect on the fibers due to the slow pressure release rate and the longer time. Therefore, when the treatment pressure is from 5MPa to 20MPa, the surface color depth value of the mixed fluid flash-exploded fibers does not change much.

Example 8:

This embodiment provides a supercritical mixed fluid flash explosion treatment method, the steps of which are basically the same as those in Embodiment 1, except that the modification treatment time is 5 min.

The cotton fiber was treated with the process in Example 8, and the dyed surface color depth value (K/S) after the treatment was 0.73, and the water retention rate of the treated sample was 64.6%.

Parameter table of cotton fiber dyeing after flash-explosion modification treatment in Table 8 Example 8

Example 9:

This embodiment provides a supercritical mixed fluid flash explosion treatment method, the steps of which are basically the same as those in Embodiment 1, except that the modification treatment time is 30 min.

Using the process in Example 9 to treat the cotton fiber, the dyed surface color depth value (K/S) after the treatment was 0.75, and the water retention rate of the treated sample was 53.2%.

Parameter table of cotton fiber dyeing after flash explosion modification treatment in table 9 embodiment 9

It can be seen from Example 1, Example 8 and Example 9 that with the prolongation of the treatment time, more moisture remains in the fiber voids. During the flash-explosion treatment, the mixed fluid flashes to increase the pore size of the cotton fibers. , the voids increase, and the water molecules are more likely to penetrate into the cotton fiber, and the fiber has better hydrophilic performance. When the treatment time is 5min, the water retention rate of cotton fiber is 64.6. When the treatment time was 10min, the water retention rate of cotton fiber was 79.0%. When the treatment time continued to prolong, the water vapor in the fiber continued to enter the fluid medium and lost more, which made the expected effect worse. When the treatment time was 30min, the water retention rate of the fiber was 53.2.

When the treatment time was from 5min to 10min, the surface color depth value of the dyed fibers increased significantly. During the high-pressure and high-temperature treatment of the mixed fluid, with the appropriate extension of time, the water vapor contained in the cotton fiber can further fully penetrate and diffuse into the fiber, and the fiber can be fully expanded. At the same time, the mixed fluid of _CO2 fluid and water vapor formed in the inner void of the fiber is released instantaneously during the flash explosion, and the resulting violent expansion causes the fiber to mechanically expand, destroying or weakening the hydrogen in the macromolecular system of the cotton fiber. bond, increasing the pore size of each micropore in the fiber. Thereby, the accessibility and dyeability of the fibers are increased, and the reactive disperse yellow SCF-AY02 dye is easier to dye the fibers in supercritical CO ₂ , so the surface color depth value is improved.

When the treatment time continued to be prolonged, the water vapor lost too much from the fiber voids, so that the surface color depth value of the mixed fluid flash-exploded fibers decreased, so that the expected results decreased. When the treatment time is 30min, the color depth value of the fiber surface is 0.75.

Example 10:

This embodiment provides a supercritical mixed fluid flash explosion treatment method, the steps of which are basically the same as those in Embodiment 1, except that the flash explosion time is 12s.

Using the process in Example 10 to treat the cotton fiber, the dyed surface color depth value (K/S) after the treatment was 1.01, and the water retention rate of the treated sample was 65.6%.

Parameter table of cotton fiber dyeing after flash-explosion modification treatment in Table 10 Example 10

Example 11:

This embodiment provides a supercritical mixed fluid flash explosion treatment method, the steps of which are basically the same as those in Embodiment 1, except that the flash explosion time is 16s.

Using the process in Example 11 to treat the cotton fiber, the dyed surface color depth value (K/S) after the treatment was 0.97, and the water retention rate of the treated sample was 47.6%.

Table 11 Parameter table of cotton fiber dyeing after flash explosion modification treatment in Example 11

It can be seen from Examples 10-11 that with the extension of the flash explosion time, the water retention rate of the mixed fluid flash explosion cotton fiber gradually decreases. In the process of mixed fluid flash explosion, prolonging the flash explosion time will lead to the slow release of the mixed fluid formed in the fiber, which will have a poorer effect on fiber expansion. Therefore, the number of voids in the fiber and the pore size of the void in the fiber will be smaller, and the affinity of the fiber will be smaller. Water performance declines.

Therefore, with the extension of the flash time, the water retention rate of the fiber decreases. When the flash time was 8s, the fiber water retention rate was 79.0%; when the flash time was 12s, the fiber water retention rate was 65.6%; when the flash time was 16s, the fiber water retention rate was 47.6%.

At the same time, with the extension of flash time, the surface color depth value of dyed fibers decreased. In the process of mixed fluid flash explosion treatment, the greater the instantaneous extrusion force of the mixed fluid on the fibers during the deflation process, the greater the energy released, which makes the intermolecular hydrogen bonds of the fibers break or weaken, and the degree of freedom of the fiber macromolecules increases. The fiber pore size becomes larger, and the proportion of the amorphous region of the fiber increases at the same time. However, prolonging the flash explosion time results in the slow release of the mixed fluid in the fiber during the flash explosion, which reduces the effect of the mixed fluid flash explosion on intermolecular hydrogen bonds, reduces the degree of freedom of macromolecules, and reduces the internal pore size of the fiber. The ratio of the amorphous area decreases, which is not conducive to the entry of the dye into the fiber, and the surface color depth value of the mixed fluid flashing decreases. When the flash time is 8s, the surface color depth of the fiber is 1.04; when the flash time is 12s, the surface color depth of the fiber is 1.01; when the flash time is 16s, the surface color depth of the fiber is 0.97 .

Example 12:

This embodiment provides a method for flash explosion treatment of supercritical mixed fluid, the steps of which are basically the same as those in embodiment 1, the difference is that the modification treatment is treated twice according to the process of embodiment 1.

Using the process in Example 12 to treat the cotton fiber, the dyed surface color depth value (K/S) after the treatment was 1.08, and the water retention rate of the treated sample was 246.3%.

Table 12 Parameter table of cotton fiber dyeing after flash explosion modification treatment in Example 12

Example 13:

This embodiment provides a method for flash explosion treatment of supercritical mixed fluid, the steps of which are basically the same as those in embodiment 1, the difference is that the modification treatment is processed three times according to the process of embodiment 1.

Using the process in Example 13 to treat the cotton fiber, the dyed surface color depth value (K/S) after the treatment was 1.19, and the water retention rate of the treated sample was 334.8%.

Table 13 Parameter table of cotton fiber dyeing after flash explosion modification treatment in Example 13

Example 14:

This embodiment provides a supercritical mixed fluid flash explosion treatment method, the steps of which are basically the same as those in embodiment 1, the difference is that the modification treatment is processed 4 times according to the process of embodiment 1.

Using the process in Example 14 to treat the cotton fiber, the dyed surface color depth value (K/S) after the treatment was 1.29, and the water retention rate of the treated sample was 541.3%.

Parameter table of cotton fiber dyeing after flash-explosion modification treatment in table 14 Example 14

From Example 1, Example 12, and Example 14, it can be seen that the water retention rate of the fiber increases with the increase of the number of flash explosions of the fiber. Especially as the number of flash explosions increases to more than 1 time, it can be seen that the fiber water retention rate increases sharply, even reaching 541.3% in the fourth treatment. It may be because some hydrogen bonds between fiber molecules are completely broken after multiple flash explosions of the mixed fluid, and the pore size of each micropore in the fiber continues to increase after multiple flash explosions, making it easier for water molecules to penetrate into the fiber. Therefore, as the number of flash explosions increases, the water retention rate of the fibers increases.

With the increase of the number of flash explosions, the surface color depth value of the mixed fluid flash explosion fibers increases. After the fiber is subjected to the mixed fluid flash explosion treatment, the intermolecular hydrogen bonds of the fiber are broken or weakened, the degree of freedom of the fiber macromolecules increases, the fiber pore size becomes larger, and the proportion of the amorphous region of the fiber is increased, so that the reactive disperse yellow SCF-AY02 dye is in the supercritical state. It is easier to dye fibers in CO ₂ , so the surface depth value increases. Compared with the untreated fiber, the fiber surface color depth value of the fiber after one treatment is significantly improved. However, with the increase of the number of flash explosions, the process of the mixed fluid flash explosion occurs again, the degree of rupture or weakening of the intermolecular hydrogen bonds increases, the degree of freedom of the fiber macromolecules continues to increase, the pore size of the pores inside the fiber continues to increase, and the amorphous The area ratio continues to increase, making it easier for the dye to dye the fiber, and the value of the color depth on the fiber surface increases. At the same time, after multiple flash explosion treatments, the water retention rate of the fibers also increased significantly.

It can be concluded from the above examples that the natural fibers or natural fiber products are packed tightly in layers in the special flash-explosion treatment unit by means of mechanical compaction, so that the natural fibers or natural fiber products are evenly distributed in the device; The treatment of non-CO ₂ media such as saturated steam is under the combined action of critical CO ₂ fluid; after a period of treatment, rapid pressure relief is carried out, and the instantaneous pressure difference causes the internal pore size of natural fibers to expand and the intermolecular hydrogen bonds of fibers to break. , The degree of freedom of fiber macromolecules is increased, the amorphous region of the fiber is increased, and the dye molecules are more likely to enter the interior of the fiber molecule, improving the dyeing performance of natural fibers or their products in supercritical CO ₂ fluid. In addition, the method has the advantages of convenient operation, simple process, short process flow, no waste water pollution and high treatment efficiency.

The method can also be applied to tops, yarns, woven fabrics, knitted fabrics, non-woven fabrics and other materials. Also, fibers, yarns or fabrics can be processed simultaneously to fully utilize the space in the flash processing unit.

The supercritical mixed fluid flash explosion treatment method for natural fibers and their products can effectively realize the modification treatment of natural fibers or their products, improve their dyeing performance in supercritical CO ₂ fluid, and solve the problem of high energy in traditional water bath dyeing. consumption, high pollution, high emissions, and difficulty in recycling and disposing of dyes. At the same time, the invention is simple and convenient to operate, and can effectively realize the processing of natural fibers, improve the dyeing performance of the natural fibers without changing the excellent properties of the natural fibers.

Finally, it should be noted that the above are only preferred embodiments of the present invention, and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, for those skilled in the art, it is still The technical solutions described in the foregoing embodiments may be modified, or some technical features thereof may be equivalently replaced. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims (10)

1. A kind of supercritical mixed fluid flash explosion treatment method of natural fiber and its product is characterized in that: comprise the following steps:

   Filling the natural fiber or natural fiber product in the flash-detonation treatment unit according to a predetermined form, and transferring the flash-detonation treatment unit into the flash-detonation treatment device;

   Connect the flash explosion treatment device to the non-CO ₂ medium device, under standard atmospheric pressure, pass the non-CO ₂ medium into the flash explosion treatment device, and disconnect the connection with the non-CO ₂ medium device after the end;

   Connect the flash-explosion treatment device to the CO ₂ medium device, fill the CO ₂ medium into the flash-explosive treatment device, and heat up at the same time;

   When the modification treatment temperature and modification treatment pressure of the mixed fluid inside the flash-detonation treatment device reach the preset values, the treatment sequence of fluid circulation and fluid static treatment is carried out for a predetermined modification treatment time, so that the fluid enters uniformly and fully Distributed in the inner phase of fibers;

   Control the pressure and/or temperature of the separation and recovery unit, and perform flash explosion treatment with different temperature differences and/or different pressure differences;

   The flash-explosion treatment device is quickly or instantaneously depressurized within the flash-explosion time, and the flash-explosion treatment is performed on natural fibers or natural fiber products;

   Turn on the gas recovery pump of the separation and recovery unit, separate and recover different media, reduce the pressure in the flash explosion system to atmospheric pressure, take out the processed samples, and complete the flash explosion treatment of dry natural fibers or natural fiber products.
2. A kind of supercritical mixed fluid flash explosion treatment method of natural fiber and product thereof according to claim 1, is characterized in that:

   The natural fiber is one or more of cotton, hemp, silk and wool.
3. A kind of supercritical mixed fluid flash explosion treatment method of natural fiber and product thereof according to claim 2, is characterized in that:

   The natural fiber product is one or more of fibers, yarns and fabrics.
4. A kind of supercritical mixed fluid flash explosion treatment method of natural fiber and product thereof according to claim 3, is characterized in that:

   When the sample is fiber, the fluffy fibers are extruded neatly and uniformly layer by layer by the action of mechanical external force, so that they can be flatly packed in the flash explosion treatment unit according to a certain tightness;

   When the sample is yarn, use mechanical external force to process the yarn so that it can be wound neatly and evenly at a certain interval, so that it can be evenly and evenly wound in the flash treatment unit;

   When the sample is a fabric, the flat fabric is wound neatly and evenly by mechanical external force, so that it can be evenly and evenly wound in the flash explosion treatment unit.
5. A kind of supercritical mixed fluid flash explosion treatment method of natural fiber and product thereof according to claim 4, is characterized in that:

   The flash-explosion processing unit is made of a non-heat-causing surface material covered with a surface material, and a plurality of hollow holes are distributed around the flash-explosion processing unit and on the central hollow tube.
6. A supercritical mixed fluid flash explosion treatment method for natural fibers and their products according to claim 5, wherein the flash explosion treatment unit is made of polytetrafluoroethylene material.
7. A kind of supercritical mixed fluid flash explosion treatment method of natural fiber and its product according to claim 6, is characterized in that: described non- _CO medium is saturated steam, superheated steam, methanol, ethanol, acetone, One or more of acid and alkali.
8. The supercritical mixed fluid flash explosion treatment method for natural fibers and their products according to claim 7, wherein the modification treatment pressure is 0-30 MPa.
9. The supercritical mixed fluid flash explosion treatment method for natural fibers and their products according to claim 8, wherein the modification treatment temperature is 90-180°C.
10. A kind of supercritical mixed fluid flash explosion treatment method of natural fiber and product thereof according to claim 9, is characterized in that: described modification treatment time is 0-60min.

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