Method for continuous dyeing of cellulose material loose fibers with indigo

Abstract

The present application belongs to the field of textile printing and dyeing processing, and discloses a method for continuous dyeing of cellulose material loose fibers with indigo. The method is as follows: cellulose material loose fibers are combed into a fiber layer by a netting machine, the fiber layer is immersed in an indigo leuco dye solution by a continuous loose fiber dyeing machine, and then is sent into a continuous oxidation reaction box to realize oxidation and color development of the indigo leuco body and complete the dyeing process. The continuous oxidation reaction box comprises a cuboid box body and a conveying system, a reaction supply system and a negative pressure filtration system in the box body. The conveying system comprises a caterpillar conveyor belt. The negative pressure filtration system comprises a negative pressure cavity and a vacuum pump, and the negative pressure cavity is used for filtering the fiber layer carried on the upper surface of the caterpillar conveyor belt. The reaction supply system comprises a temperature control unit and an oxidation medium supply unit. The present application can improve production efficiency, ensure dyeing depth and uniformity of the fibers, save dyeing water, and reduce the amount of caustic soda and sodium hydrosulfite.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of textile printing and dyeing, and relates to a method for continuous dyeing of cellulose material loose fibers with indigo. BACKGROUND

[0002] At present, the yarn indigo dyeing process is adopted for dyeing of traditional denim fabrics. In order to fully oxidize and achieve the ideal dyeing depth, repeated oxidation and color development are required, which is extremely strict in terms of site and equipment requirements.

[0003] In addition, the main components of the dye liquor in each dyeing tank include indigo leuco, indigo suspended particles, sodium hydrosulfite, caustic soda, and dyeing dispersants and penetrants. This results in a large amount of wastewater discharge, and the wastewater contains a large amount of suspended matter, colloidal organic dyes, chemicals, and penetrants and other surfactants, which have the characteristics of high colority, high pollutant concentration, strong alkalinity, and poor biodegradability, and do not meet the requirements of green and sustainable development of the industry.

[0004] In the traditional process, loose fibers cannot be continuously dyed. To solve this problem, both the patent application with the application publication number CN105155166A and the patent application with the application publication number CN116971191A are to make the loose fibers into a stitched body by using a stitching device, and then to perform multiple dyeing and immersion of liquid oxidizing agent. However, the mechanical stitching and the interlayer structure naturally form a penetration barrier, uneven distribution of oxidizing agent, and residual liquid retention, which will cause "strip color difference" and "skin-core color difference"; and these structural defects cannot be completely solved by multiple dyeing, oxygen removal, or wastewater reuse.

[0005] The patent application with the application publication number CN111575940A is to make the loose fibers into a net shape by drawing, and to use active dye spray dyeing, and to dye after stacking for a certain time without oxidation and color development. This method is a netting cold stacking dyeing scheme for active dyes, which completely does not consider the core characteristics of indigo dye "reduction-oxidation cycle, accurate oxidation, and immediate fixation", and the structural design itself cannot meet the core needs of continuous indigo dyeing of loose fibers.

[0006] Therefore, it is necessary to provide a method for continuous dyeing of cellulose material loose fibers with indigo, so as to solve the above problems, which has very important significance. SUMMARY

[0007] The present application belongs to the field of textile printing and dyeing, and relates to a method for continuous dyeing of cellulose material loose fibers with indigo.

[0008] To achieve the above-mentioned purpose, the technical scheme adopted by the present application is as follows:

[0009] A method for continuous dyeing of cellulose material loose fibers with indigo, the cellulose material loose fibers are combed into a fiber layer by a netting machine, the fiber layer is immersed in an indigo leuco dye solution by a continuous loose fiber dyeing machine, and then is sent into a continuous oxidation reaction box to realize oxidation and color development of the indigo leuco body and complete the dyeing process.

[0010] The continuous oxidation reaction box comprises a cuboid box body and a conveying system, a reaction supply system and a negative pressure filtration system located in the box body.

[0011] The conveying system is located below the reaction supply system and extends through the front and rear ends along the length direction of the box body, and the core function is to continuously carry the loose fibers through the oxidation reaction box; the conveying system comprises a track-type conveyor belt, and the track-type conveyor belt is a nylon mesh conveyor belt; the negative pressure filtration system comprises a negative pressure cavity, a pressure regulating valve and a vacuum pump; the number of the negative pressure cavities is more than 3, which are arranged between the upper and lower tracks of the track-type conveyor belt and close to the lower surface of the upper track, and the negative pressure cavities are used for filtering the fiber layer carried on the upper surface of the upper track; the vacuum pump is arranged at the rear end of the box body, all the negative pressure cavities are connected to the vacuum pump through pipelines, and a pressure regulating valve is arranged on each pipeline close to each negative pressure cavity; along the conveying direction of the fiber layer, the pressure of the middle negative pressure cavity (i.e. the negative pressure cavity with a pressure of-35~-40 kPa) is greater than that of the rear negative pressure cavity (i.e. the negative pressure cavity with a pressure of-20~-30 kPa), and the pressure of the front negative pressure cavity (i.e. the negative pressure cavity with a pressure of-15~-20 kPa) is the smallest.

[0012] The reaction supply system is located above the conveying system and comprises a temperature control unit and an oxidation medium supply unit from top to bottom; the oxidation medium supply unit comprises a hydrogen peroxide atomizer, a mist conveying pipeline and a mist nozzle; the hydrogen peroxide atomizer is arranged at the rear end of the box body and above the vacuum pump; the number of the mist conveying pipelines is 3-10, preferably 6; the hydrogen peroxide atomizer is connected to all the mist conveying pipelines; each mist conveying pipeline is zigzag or arranged in multiple non-closed triangles; the extension direction of the mist conveying pipeline is the width direction of the box body; all the mist conveying pipelines are offset by 50-100 mm in the width direction of the box body in turn.

[0013] As a preferred technical solution:

[0014] The method for continuously dyeing cellulose material loose fibers with indigo as described above, the conveying system further comprises a transmission roller at the front end of the caterpillar conveyor and a guide roller at the rear end; the surface of the transmission roller is covered with a rubber non-slip layer (to prevent the caterpillar from slipping), the roller shaft is fixed to the inner walls on both sides of the box in the width direction through bearings, and one end is connected to a speed reducer motor (to provide circulating power for the caterpillar), which is the driving roller; the guide roller is fixed to the inner walls on both sides of the box in the width direction through bearings, the diameter and length of the guide roller and the transmission roller are the same, and the roller shafts are parallel and at the same height.

[0015] The method for continuously dyeing cellulose material loose fibers with indigo as described above, the aperture of the mesh on the caterpillar conveyor is 10-70 mm;

[0016] The top of the negative pressure cavity is a stainless steel mesh with a mesh aperture of 3-5 mm, and the bottom is a negative pressure interface with a diameter of 50 mm; the single negative pressure cavity is a cuboid structure (the width can be adjusted according to the width of the loose fibers), and the material is 304 stainless steel; along the direction from the transmission roller to the guide roller, the present application first removes 10-15% of the free solution on the surface layer by low negative pressure of-15 to-20 kPa, breaks the "continuous liquid film" easily formed under high liquid rate (roll-up rate), avoids the blockage of the mist by the liquid film, and then forms a thickness direction pressure difference by high negative pressure of-35 to-40 kPa to drive the airflow to penetrate the viscous solution, reduce the high liquid rate, and activate the fiber layer pores to open the channel for the penetration of the mist. Finally, the fiber layer liquid amount is controlled by medium pressure fine extraction of-20 to-30 kPa, which not only retains sufficient indigo leuco form on the fiber, but also avoids excessive dilution of the mist by the solution, solves the contradiction between "insufficient oxidation" and "waste of mist" under high liquid rate, and realizes dynamic adaptation to high liquid rate through this gradient negative pressure "staged liquid control", which is an innovative breakthrough that cannot be achieved by the existing single negative pressure system.

[0017] The gap between the negative pressure cavity and the lower surface of the upper caterpillar is ≤3 mm.

[0018] The method for continuously dyeing cellulose material loose fibers with indigo as described above, the temperature control unit comprises 3-10 (preferably 8) steam heating pipes uniformly distributed along the length direction of the box, the distance between every two adjacent steam heating pipes is 200 mm, and they are connected to each other in U shape at one end, and the surface of the pipe is provided with heat dissipation fins.

[0019] The method for continuously dyeing cellulose material loose fibers with indigo as described above, the steam heating pipe, the mist conveying pipe and the mist nozzle are wrapped by a heat preservation layer, and the material of the heat preservation layer is flame-retardant rock wool.

[0020] The temperature control unit further comprises a temperature sensing switch arranged at the steam inlet of the steam heating pipe, for controlling the temperature in the steam heating pipe, and further controlling the temperature in the continuous oxidation reaction box.

[0021] The temperature in the continuous oxidation reaction box is 20-80℃.

[0022] The temperature control of the U-shaped steam pipe provides a "thermodynamic optimization environment" for the oxidation reaction, and promotes the puffing of the fiber structure. The in-box temperature of 20-80℃ increases the decomposition rate of hydrogen peroxide, and the concentration of generated hydroxyl radicals (·OH) is also increased, which can quickly oxidize the indigo leuco form to indigo pigment (oxidized state). Without heating measures or using a non-U-shaped design (such as a single straight pipe) for the steam pipe, local low temperature and local high temperature will occur, resulting in uneven oxidation and failing to meet the uniformity requirements of continuous dyeing.

[0023] The number of mist spray nozzles on each mist conveying pipe is 10-100, the aperture of each mist spray nozzle is 10-20mm, the shape of the mist sprayed by each mist spray nozzle is fan-shaped, the spray angle is 30°-165°, and the directions of all mist spray nozzles are the same.

[0024] The cellulose material loose fiber is cotton loose fiber, viscose loose fiber or modal loose fiber.

[0025] The cellulose material loose fiber is carded into a fiber layer by using a double-air vibration pneumatic cotton box and an air-laid machine, and the grammage of the fiber layer is 500-2500g / m 2 ;

[0026] The speed of the continuous loose fiber dyeing machine is 2-15m / min, and the volume is 50-200L.

[0027] The concentration of the dye in the indigo leuco form dyeing solution is 1-100g / L, the concentration of the sodium hydrosulfite is 5-80g / L, the concentration of the sodium hydroxide is 5-60g / L, and the concentration of the sodium sulfate is 10-100g / L.

[0028] The fiber layer is immersed in the indigo leuco form dyeing solution, and the pick-up rate is 60-130%; the speed of the crawler belt conveyor is 2-15m / min.

[0029] The method for continuous dyeing of loose cellulose fibers with indigo, as described above, involves a hydrogen peroxide solution concentration of 1~50 g / L in a hydrogen peroxide atomizer; a vacuum pump pumping speed of 100 L / s with an ultimate vacuum degree ≤1 Pa; and a mist flow rate of 15~30 m / s.

[0030] This invention achieves precise control of the reaction rate by linking the spray volume and gradient negative pressure value in real time through a PLC system: when the oxidation rate is detected to be too fast, the PLC system immediately reduces the spray volume and simultaneously lowers the negative pressure in the strong suction chamber to slow down the oxidation reaction and allow time for the leuco form to diffuse to the center. If the oxidation rate is too slow, the spray volume is increased, the negative pressure in the strong suction chamber is increased, and the mist penetration power is enhanced to ensure that the leuco form in the center is fully oxidized.

[0031] Invention principle:

[0032] The purpose of this invention is to enable hydrogen peroxide mist to be fully dispersed on loose fibers, oxidizing and developing color, thereby achieving continuous indigo dyeing of cellulose loose fibers. Specifically, the continuous oxidation reaction chamber constructs an oxidation system of "uniform coverage - directional penetration - efficient reaction - continuous stability" through dynamic coupling of "spray + negative pressure filtration", fluid control of special pipeline configuration, and precise regulation of the temperature field, achieving full dispersion and deep penetration of hydrogen peroxide mist in loose fibers.

[0033] (1) Uniform dispersion of hydrogen peroxide mist;

[0034] The hydrogen peroxide mist delivery pipeline adopts a composite design of sawtooth or multiple non-closed triangles connected together, and multiple spray outlets, ensuring full-space coverage of hydrogen peroxide mist without dead angles. Multiple pipelines are offset alternately in a sawtooth shape along the width direction, and with multiple spray outlets in each pipeline, a "three-dimensional staggered spray field" is formed, thereby reconstructing the flow field dynamics. This allows the droplets to not only fall vertically but also diffuse horizontally, covering the full width of the fiber layer, eliminating blind spots at the edges of straight pipelines, and ensuring that the loose fibers, whether at the center or edge of the track, can contact an equal amount of oxidizing medium.

[0035] If a straight-lined pipe arrangement (without a serrated design) is used, the parallel spray direction will lead to "overlapping concentration in the middle and missed spraying on both sides," resulting in significant color differences in fiber oxidation and failing to meet the uniformity requirements of continuous dyeing. Furthermore, the straight-lined pipe design can only achieve surface coverage in a two-dimensional plane, and cannot meet the "full-layer penetration" requirement of a three-dimensional loose fiber layer under high liquid load conditions. The serrated design, on the other hand, supplements the edge spray through staggered coverage, reducing the standard deviation of the spray volume and avoiding the problems of oversaturation in the middle causing liquid film blockage of pores and insufficient edge spraying leading to inadequate oxidation, thus achieving uniform concentration across the entire width.

[0036] (2) The penetration of fog into the interior of the fiber layer;

[0037] The synergistic effect of the negative pressure chamber and the upper track creates a "top-down directional airflow field," providing an active driving force for mist penetration. Under negative pressure, the fiber layer adheres to the track through the stainless steel mesh, flattening the loose fibers into a uniform porous structure. A significant pressure difference is created between the upper and lower surfaces of the fiber layer, driving the mist to flow directionally from the upper spray nozzle (high-pressure zone) to the lower negative pressure chamber (low-pressure zone). The high-speed airflow "carries" mist droplets through the fiber gaps and even into the interior through micropores on the fiber surface.

[0038] If the negative pressure system is removed, the droplets cannot penetrate the fiber layer due to gravity settling alone, resulting in a layering phenomenon of "surface over-oxidation and internal unoxidation". The indigo chromophores cannot be completely converted into the oxidized state, and the color fastness (dry and wet rubbing) decreases.

[0039] If a single negative pressure chamber with a fixed negative pressure value is used, it can only achieve surface adsorption of two-dimensional fabrics, and cannot cope with the problem of "high-humidity solution agglomeration and surface liquid film blockage" in the loose fiber layer under a certain liquid carrying rate. This invention sets up multiple negative pressure chambers to construct a gradient negative pressure field of "low-pressure pre-extraction - high-pressure strong extraction - medium-pressure fine extraction" along the loose fiber conveying direction. By "stage-wise control of liquid carrying volume" of the gradient negative pressure, dynamic adaptation to high liquid carrying rates is achieved, which is an innovative breakthrough that existing single negative pressure systems cannot achieve. Specifically, the front end uses a low negative pressure to extract the surface free solution, breaking the "continuous liquid film" that is easily formed under high liquid carrying rate, thus preventing the mist from being blocked by the liquid film and unable to penetrate; the middle area uses a high negative pressure to form a pressure difference in the thickness direction, driving the airflow to penetrate the viscous solution, reducing the high liquid carrying rate, and at the same time activating the pores of the fiber layer, opening up channels for mist penetration; the rear end uses medium pressure to control the amount of liquid carried by the fiber layer, which not only retains sufficient indigo leuco on the fiber, but also avoids excessive dilution of the mist by the solution, thus resolving the contradiction of insufficient oxidation or mist waste under high liquid carrying rate.

[0040] A certain liquid retention rate is an inevitable state for loose fibers after being dipped in indigo leuco dye liquor in a continuous loose fiber dyeing machine (the process requirement is a retention rate of 60-130%). In this state, the loose fiber layer exhibits characteristics of "high moisture content, high viscosity, and three-dimensional looseness". The "spray + vacuum filtration" technology proposed in this invention is a necessary condition for realizing continuous indigo dyeing of loose fibers.

[0041] (i) The liquid film barrier must be broken through "gradient vacuum filtration"; otherwise, the mist cannot penetrate and will lead to oxidation failure.

[0042] Under high liquid carrying capacity, a continuous viscous liquid film (composed of a mixed solution of indigo leuco, caustic soda, and sodium hydrosulfite) easily forms on the surface of the loose fiber layer. If the existing single negative pressure technology (-5~-10kPa) is used, only surface adsorption can be achieved, and the liquid film cannot be broken: if the mist is blocked by the liquid film on the surface of the fiber layer, it can only oxidize the surface fiber, resulting in an extreme color difference of "deep blue on the surface and light yellow in the middle layer" (ΔE>2); the leuco solution under the liquid film cannot come into contact with the mist and will continue to hydrolyze in the alkaline environment, failing to meet the requirements for dyeing depth.

[0043] The gradient vacuum filtration of this invention, by extracting the solution in stages and breaking the liquid film, is a technical means to ensure that the mist can penetrate the fiber layer with a high liquid carrying rate, and it is irreplaceable.

[0044] (ii) The reaction rate must be controlled by “spray-filtration synergy”, otherwise oxidation and diffusion mismatch will lead to staining defects;

[0045] At high liquid carrying rates, the diffusion rate of indigo leuco in viscous solutions is significantly reduced (the diffusion coefficient is only 10 at 20°C). -10 m 2 If the oxidation rate is too fast, the leuco form will be oxidized before it diffuses to the middle of the fiber layer, resulting in a large color difference and the dry rubbing color fastness will drop from grade 3 to 4 to grade 1 to 2. If the oxidation rate is too slow, there will be insufficient mist to oxidize the leuco form after it diffuses to the middle of the fiber layer, the hydrolysis rate will increase, and the color will be dull.

[0046] Beneficial effects:

[0047] (1) The present invention can uniformly spray the atomized hydrogen peroxide aqueous solution onto the surface of the fiber layer through the atomized conveying pipe of a specific shape, and rapidly adsorb and penetrate the atomized hydrogen peroxide aqueous solution into the fiber layer under the cooperation of the negative pressure filtration system. Under the rapid oxidation effect of the atomized hydrogen peroxide aqueous solution, the indigo leuco form is efficiently oxidized and fixed on the loose fiber, thereby completing the dyeing process. This can improve production efficiency, save dyeing water, reduce the amount of caustic soda, sodium hydrosulfite, etc., and significantly reduce wastewater discharge.

[0048] (2) This invention reduces the problems of large number of dyeing tanks, large water consumption, large chemical consumption and large wastewater discharge in the traditional yarn indigo dyeing process, improves production efficiency, and ensures the dyeing depth and dyeing uniformity of the fiber.

[0049] (3) The color difference ΔE between the upper and inner layers and the lower layer of the fiber layer after dyeing is less than 1, indicating that the dye solution penetrates evenly and the hydrogen peroxide mist has fully penetrated and oxidized the fiber layer. Attached Figure Description

[0050] Figure 1 This is a schematic diagram of the continuous oxidation reaction chamber of the present invention;

[0051] Figure 2 This is a schematic diagram of a single mist delivery pipe of the present invention when multiple non-closed triangles are connected and arranged together;

[0052] Figure 3 This is a schematic diagram of the single mist delivery pipe of the present invention being serrated;

[0053] Figure 4 This is a schematic diagram of the stainless steel mesh at the top of the negative pressure chamber of the present invention;

[0054] Figure 5 This is a top view of the mist delivery pipe and fiber layer of the present invention;

[0055] Among them, 1-tracked conveyor belt, 2-drive roller, 3-guide roller, 4-negative pressure chamber, 5-vacuum pump, 6-steam heating pipe, 7-temperature sensing switch, 8-hydrogen peroxide atomizer, 9-mist conveying pipe, 10-mist nozzle, 11-insulation layer, 12-filtration residue collection box, 13-gas-liquid separator, 14-pressure regulating valve, 15-fiber layer. Detailed Implementation

[0056] The present invention will be further described below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Furthermore, it should be understood that after reading the teachings of this invention, those skilled in the art can make various alterations or modifications to the invention, and these equivalent forms also fall within the scope defined by the appended claims.

[0057] To ensure that the performance of the substances used in each embodiment and comparative example is fully disclosed, the manufacturers and brands of the substances are specified. Other products from manufacturers and brands that conform to the limitations of this invention are also feasible.

[0058] The test methods for the relevant performance indicators in the following embodiments and comparative examples are as follows:

[0059] K / S value: The upper, middle and lower fiber layers of the dyed fiber layers in each embodiment and comparative example were used as samples. The apparent color depth (i.e., K / S value) of the samples was tested using a Datacolor 1000 computer colorimeter and the average value was taken. The test light source was D65 10°.

[0060] Color difference ΔE: The upper and middle fiber layers of the dyed fiber layers in each embodiment and comparative example were used as samples. The color difference (i.e., ΔE value) of the samples was tested and calculated using a Datacolor 1000 computer colorimeter. The test light source was D65 10°.

[0061] Dry rubbing color fastness grade and wet rubbing color fastness grade: The dyed fibers in each example and comparative example were used as samples, and the dry rubbing color fastness grade and wet rubbing color fastness grade of the samples were tested in accordance with GB / T 3920-2008 "Textiles - Tests for color fastness - Color fastness to rubbing" standard.

[0062] A continuous oxidation reaction chamber used in a method for continuous dyeing of loose cellulose fibers into indigo, such as... Figure 1 As shown, it includes a rectangular box and a conveying system, a reaction supply system and a negative pressure filtration system located inside the box;

[0063] The conveying system is located below the reaction supply system and runs through the front and rear ends along the length of the tank.

[0064] The conveying system includes a tracked conveyor belt 1, a drive roller 2 located at the front end of the tracked conveyor belt 1, and a guide roller 3 located at the rear end;

[0065] The tracked conveyor belt 1 is a nylon mesh conveyor belt with a mesh opening diameter of 10~70mm;

[0066] The surface of the transmission roller 2 is covered with a rubber anti-slip layer. Both ends of the roller shaft are fixed to the inner walls on both sides of the box in the width direction by bearings, and one end is connected to the reduction motor.

[0067] The guide roller 3 is fixed to the inner wall of both sides of the box in the width direction by bearings at both ends. The guide roller 3 and the transmission roller 2 have the same diameter and length, and the roller shafts are parallel and at the same height.

[0068] The negative pressure filtration system includes a negative pressure chamber 4, a pressure regulating valve 14, a filtration residue collection tank 12, and a vacuum pump 5;

[0069] like Figure 4 As shown, the top of the negative pressure chamber 4 is a stainless steel mesh with a mesh size of 3~5mm, and the bottom is a negative pressure interface with a diameter of 50mm.

[0070] There are three or more negative pressure chambers 4, which are set between the upper and lower tracks of the tracked conveyor belt 1 and are evenly distributed along the length of the upper track. The gap between the negative pressure chamber 4 and the lower surface of the upper track is ≤3mm. The negative pressure chamber 4 is used to filter the fiber layer 15 carried on the upper surface of the upper track.

[0071] The vacuum pump 5 is located at the rear end of the chamber. All negative pressure chambers 4 are connected to the vacuum pump 5 simultaneously through 304 stainless steel pipes with a diameter of 100mm. A pressure regulating valve 14 is installed on the pipe near each negative pressure chamber 4.

[0072] Along the conveying direction of fiber layer 15, the pressure of the middle negative pressure chamber 4 is greater than the pressure of the rear negative pressure chamber 4, which is greater than the pressure of the front negative pressure chamber 4.

[0073] The reaction supply system is located above the conveying system, and the reaction supply system includes a temperature control unit and an oxidation medium supply unit from top to bottom.

[0074] The temperature control unit includes 3 to 10 steam heating pipes 6 evenly distributed along the length of the chamber and a temperature sensing switch 7;

[0075] Temperature sensing switch 7 is installed at the air inlet of steam heating pipe 6 to control the internal temperature of continuous oxidation reaction chamber; the distance between each two adjacent steam heating pipes 6 is 200mm, and they are connected to each other in a U-shape at one end; heat dissipation fins are provided on the surface of steam heating pipe 6.

[0076] The oxidation medium supply unit includes a hydrogen peroxide atomizer 8, a mist delivery pipe 9, and mist nozzles 10 uniformly arranged on the mist delivery pipe 9;

[0077] The hydrogen peroxide atomizer 8 is located at the rear of the chamber and above the vacuum pump 5;

[0078] The hydrogen peroxide atomizer 8 has a volume of 50L and is made of 316L stainless steel. It has a liquid inlet on the top and a liquid level observation window (scale 0~50L) on the side. It is equipped with a high-pressure ultrasonic atomizing plate (frequency 2.4MHz, atomization volume 0~30L / h). The bottom outlet is connected to the mist delivery pipe 9 through a φ25mm solenoid valve pipe.

[0079] The number of atomizing delivery pipes 9 is 3 to 10, and the hydrogen peroxide atomizer 8 is connected to all atomizing delivery pipes simultaneously, such as... Figure 2 , Figure 3 As shown, a single mist delivery pipe 9 is either serrated or formed by multiple non-closed triangles connected together. The extension direction of the mist delivery pipe is the width direction of the box. All mist delivery pipes 9 are alternately offset by 50~100mm in the width direction of the box.

[0080] Each mist delivery pipe 9 has 10 to 100 mist nozzles 10, which are evenly distributed along the length of the pipe. The distance between two adjacent spray outlets is 150 mm. The diameter of each mist nozzle 10 is 10 to 20 mm. The mist sprayed from each mist nozzle 10 is fan-shaped, and the spray angle is 30° to 165°. All mist nozzles 10 face the same direction.

[0081] The steam heating pipe 6, the mist conveying pipe 9 and the mist nozzle 10 are all wrapped by the insulation layer 11, which is made of flame-retardant rock wool.

[0082] The filtration residue collection box 12 is located at the rear end of the box body and below the vacuum pump 5. It has a rectangular structure (length 0.6m, width 0.5m, height 0.5m), a volume of 100L, is made of PPR, and is connected to the liquid outlet of the gas-liquid separator 13.

[0083] Example 1

[0084] A method for continuous dyeing of loose cellulose fibers with indigo, comprising the following steps:

[0085] (1) Preparation of raw materials and equipment used;

[0086] Cellulose material loose fiber: cotton loose fiber, manufacturer Aksu Hongxin Cotton Industry Co., Ltd., variety 65435;

[0087] Dye: Indigo, manufactured by Shanghai Binyou New Material Technology Co., Ltd., brand name: Indigo ID923;

[0088] Sodium dithionite;

[0089] Indigo leuco dye solution: composed of dye at a concentration of 5 g / L, sodium hydrosulfite at a concentration of 10 g / L, sodium hydroxide at a concentration of 5 g / L, and sodium sulfate at a concentration of 20 g / L;

[0090] Continuous oxidation reaction chamber: The above-mentioned continuous oxidation reaction chamber is adopted, wherein the mesh aperture of the nylon mesh conveyor belt is 50mm; there are 5 negative pressure chambers, and along the direction from the drive roller to the guide roller, the mesh aperture of the top of the 5 negative pressure chambers is 5mm, and the pressure values ​​of the 5 negative pressure chambers are -15kPa, -35kPa, -35kPa, -25kPa, and -20kPa, respectively; the gap between the negative pressure chamber and the lower surface of the upper conveyor belt is 2mm; there are 5 steam heating pipes and 5 mist conveying pipes. The shape of each mist conveying pipe is serrated, and each mist conveying pipe has 60 mist nozzles, each mist nozzle has an aperture of 15mm, and the spray angle is 90°;

[0091] The total height of the continuous oxidation reaction chamber is 2.5m, the total length from front to back (i.e., from the front track inlet to the rear track outlet) is 5m, and the total width from left to right is 2.5m.

[0092] The tracked conveyor belt is 1.8m wide, 5mm thick, and has a closed-loop circumference of 9.6m (i.e., 4.6m for the upper layer + 4.6m for the lower layer + 0.4m for the arc length of the front and rear rollers).

[0093] The drive roller and guide roller are made of 304 stainless steel, with a diameter of 300mm and a length of 1.8m.

[0094] The material of a single steam heating pipe is 304 stainless steel, with a pipe diameter of 50mm and a wall thickness of 3mm;

[0095] The mist delivery pipe is made of PPR, with a single pipe diameter of 40mm and a length of 4.6m;

[0096] (2) The loose fibers of cellulose material are combed into a weight of 800 g / m by using a double-air vibration pneumatic cotton box and an airflow web forming machine. 2 Fiber layer;

[0097] (3) The fiber layer is impregnated with indigo leuco dye liquor in a continuous loose fiber dyeing machine with a volume of 100L and a speed of 15m / min; wherein the pick-up rate of the fiber layer impregnated with indigo leuco dye liquor is 100%;

[0098] (4) The impregnated fiber layer is fed into a continuous oxidation reaction chamber at a temperature of 30°C via a crawler conveyor belt. The conveying system will uniformly spray atomized hydrogen peroxide aqueous solution onto the surface of the fiber layer (where the top view of the mist conveying pipe and the fiber layer is shown in the figure). Figure 5 As shown in the figure, the atomized hydrogen peroxide solution is then rapidly adsorbed and penetrated into the cotton fiber layer through a negative pressure filtration system to achieve oxidation and fixation of the indigo leuco form. After the fiber layer comes out of the continuous oxidation reaction chamber, it undergoes deoxygenation washing, acid washing, soaping, water washing, drying, and packaging in sequence to complete the dyeing process. The speed of the conveyor belt is 5 m / min, the concentration of hydrogen peroxide solution in the hydrogen peroxide atomizer is 2 g / L, the atomizer flow rate is 15 m / s, the spray volume (i.e., the amount of atomized gas) is 15 L / h, the vacuum pump pumping speed is 100 L / s, and the ultimate vacuum degree is 0.1 Pa.

[0099] The spray volume of the above-mentioned conveying system is linked with the negative pressure value of each negative pressure chamber in real time through the PLC system, so that the amount of atomized hydrogen peroxide solution sprayed can be adjusted synchronously with the negative pressure value of each negative pressure chamber, ensuring that the mist penetrates in a directional manner along the three-dimensional direction of "thickness-width-length" under the pressure difference drive, and the middle fiber layer can be almost completely oxidized.

[0100] The core of the PLC system consists of a signal acquisition module, a PLC control center, and an execution drive module, ensuring precise coordination between spray volume and gradient negative pressure value;

[0101] The signal acquisition module includes a spray volume detection unit and a negative pressure detection unit;

[0102] The spray volume detection unit includes a mass flow sensor installed on the hydrogen peroxide mist delivery pipeline, which is used to collect the actual total spray volume data in real time;

[0103] The negative pressure detection unit includes high-precision absolute pressure sensors installed on the branch negative pressure pipes of each gradient negative pressure chamber, which are used to collect the actual negative pressure value of each negative pressure chamber in real time.

[0104] The data acquired by the sensors in the spray volume detection unit and the negative pressure detection unit are all connected to the PLC analog input module to ensure the real-time performance and accuracy of data acquisition;

[0105] The PLC control center includes a built-in linkage control algorithm program that supports preset basic parameters such as "spray volume - negative pressure value", real-time display of operating data (such as current spray volume and negative pressure value of each chamber) and fault alarms.

[0106] The actuation drive module includes an electronic spray volume regulating valve installed on the main outlet pipe of the hydrogen peroxide atomizer and electronic pressure regulating valves installed on the branch pipes of each negative pressure chamber.

[0107] The K / S value of the dyed fiber layer is 7.34, the color difference ΔE is 0.32, the dry rubbing color fastness grade is 4, and the wet rubbing color fastness grade is 3-4.

[0108] Example 2

[0109] A method for continuous dyeing of loose cellulose fibers with indigo, comprising the following steps:

[0110] (1) Preparation of raw materials and equipment used;

[0111] Cellulose material loose fiber: cotton loose fiber, manufacturer is Aksu Hongxin Cotton Industry Co., Ltd., variety is 65435;

[0112] Dye: Indigo, manufactured by Shanghai Binyou New Material Technology Co., Ltd., brand name: Indigo ID923;

[0113] Sodium dithionite;

[0114] Indigo leuco dye solution: composed of dye with a concentration of 50 g / L, sodium hydrosulfite with a concentration of 80 g / L, sodium hydroxide with a concentration of 50 g / L, and sodium sulfate with a concentration of 100 g / L.

[0115] Continuous oxidation reaction chamber: The above-mentioned continuous oxidation reaction chamber is adopted, wherein the mesh aperture of the nylon mesh conveyor belt is 50mm; there are 5 negative pressure chambers, and along the direction from the drive roller to the guide roller, the mesh aperture of the top of the 5 negative pressure chambers is 5mm, and the pressure values ​​of the 5 negative pressure chambers are -18kPa, -40kPa, -40kPa, -30kPa, and -25kPa, respectively; the gap between the negative pressure chamber and the lower surface of the upper conveyor belt is 2mm; there are 5 steam heating pipes and 5 mist conveying pipes. The shape of each mist conveying pipe is serrated, and each mist conveying pipe has 60 mist nozzles, each mist nozzle has an aperture of 15mm, and the spray angle is 90°;

[0116] The total height of the continuous oxidation reaction chamber is 2.5m, the total length from front to back (i.e., from the front track inlet to the rear track outlet) is 5m, and the total width from left to right is 2.5m.

[0117] The tracked conveyor belt is 1.8m wide, 5mm thick, and has a closed-loop circumference of 9.6m (i.e., 4.6m for the upper layer + 4.6m for the lower layer + 0.4m for the arc length of the front and rear rollers).

[0118] The drive roller and guide roller are made of 304 stainless steel, with a diameter of 300mm and a length of 1.8m.

[0119] The material of a single steam heating pipe is 304 stainless steel, with a pipe diameter of 50mm and a wall thickness of 3mm;

[0120] The mist delivery pipe is made of PPR, with a single pipe diameter of 40mm and a length of 4.6m;

[0121] (2) The loose fibers of cellulose material are combed into a weight of 1800 g / m by using a double-air vibration pneumatic cotton box and an airflow web forming machine. 2 Fiber layer;

[0122] (3) The fiber layer is immersed in indigo leuco dye liquor in a continuous loose fiber dyeing machine with a volume of 100L and a speed of 8m / min; wherein the pick-up rate of the fiber layer in the indigo leuco dye liquor is 100%;

[0123] (4) The impregnated fiber layer is fed into a continuous oxidation reaction chamber at a temperature of 60°C by a crawler conveyor belt. The conveying system will spray the atomized hydrogen peroxide aqueous solution evenly onto the surface of the fiber layer. Then, the atomized hydrogen peroxide aqueous solution will be rapidly adsorbed and penetrated into the cotton fiber layer by a negative pressure filtration system to achieve oxidation and fixation of indigo leuco. After the fiber layer comes out of the continuous oxidation reaction chamber, it will be subjected to deoxygenation water washing, acid washing, soap washing, water washing, drying, and packaging in sequence to complete the dyeing process. The speed of the crawler conveyor belt is 5m / min, the concentration of hydrogen peroxide aqueous solution in the hydrogen peroxide atomizer is 50g / L, the atomization flow rate is 25m / s, the spray volume (i.e. the amount of atomized gas) is 30L / h, the pumping speed of the vacuum pump is 100L / s, and the ultimate vacuum degree is 0.6Pa.

[0124] The spray volume of the above-mentioned conveying system is linked with the negative pressure value of each negative pressure chamber in real time through the PLC system, so that the amount of atomized hydrogen peroxide solution sprayed can be adjusted synchronously with the negative pressure value of each negative pressure chamber, ensuring that the mist penetrates in a directional manner along the three-dimensional direction of "thickness-width-length" under the pressure difference drive, and the middle fiber layer can be almost completely oxidized.

[0125] The core of the PLC system consists of a signal acquisition module, a PLC control center, and an execution drive module, ensuring precise coordination between spray volume and gradient negative pressure value;

[0126] The signal acquisition module includes a spray volume detection unit and a negative pressure detection unit;

[0127] The spray volume detection unit includes a mass flow sensor installed on the hydrogen peroxide mist delivery pipeline, which is used to collect the actual total spray volume data in real time;

[0128] The negative pressure detection unit includes high-precision absolute pressure sensors installed on the branch negative pressure pipes of each gradient negative pressure chamber, which are used to collect the actual negative pressure value of each negative pressure chamber in real time.

[0129] The data acquired by the sensors in the spray volume detection unit and the negative pressure detection unit are all connected to the PLC analog input module to ensure the real-time performance and accuracy of data acquisition;

[0130] The PLC control center includes a built-in linkage control algorithm program that supports preset basic parameters such as "spray volume - negative pressure value", real-time display of operating data (such as current spray volume and negative pressure value of each chamber) and fault alarms.

[0131] The actuation drive module includes an electronic spray volume regulating valve installed on the main outlet pipe of the hydrogen peroxide atomizer and electronic pressure regulating valves installed on the branch pipes of each negative pressure chamber.

[0132] The K / S value of the dyed fiber layer is 27.86, the color difference ΔE is 0.68, the dry rubbing color fastness grade is 3, and the wet rubbing color fastness grade is 2.

[0133] Example 3

[0134] A method for continuous dyeing of loose cellulose fibers with indigo, comprising the following steps:

[0135] (1) Preparation of raw materials and equipment used;

[0136] Cellulose material loose fiber: cotton loose fiber, manufacturer is Aksu Hongxin Cotton Industry Co., Ltd., variety is 65435;

[0137] Dye: Indigo, manufactured by Shanghai Binyou New Material Technology Co., Ltd., brand name: Indigo ID923;

[0138] Sodium dithionite;

[0139] Indigo leuco dye solution: composed of dye at a concentration of 10 g / L, sodium hydrosulfite at a concentration of 20 g / L, sodium hydroxide at a concentration of 10 g / L, and sodium sulfate at a concentration of 30 g / L.

[0140] Continuous oxidation reaction chamber: The above-mentioned continuous oxidation reaction chamber is adopted, wherein the mesh aperture of the nylon mesh conveyor belt is 50mm; there are 5 negative pressure chambers, and along the direction from the drive roller to the guide roller, the mesh aperture of the top of the 5 negative pressure chambers is 5mm, and the pressure values ​​of the 5 negative pressure chambers are -16kPa, -36kPa, -36kPa, -26kPa, and -21kPa, respectively; the gap between the negative pressure chamber and the lower surface of the upper conveyor belt is 2mm; there are 5 steam heating pipes and 5 mist conveying pipes. Each mist conveying pipe is arranged in the shape of multiple non-closed triangles connected together, and each mist conveying pipe has 60 mist nozzles, each mist nozzle has an aperture of 15mm, and the spray angle is 90°;

[0141] The total height of the continuous oxidation reaction chamber is 2.5m, the total length from front to back (i.e., from the front track inlet to the rear track outlet) is 5m, and the total width from left to right is 2.5m.

[0142] The tracked conveyor belt is 1.8m wide, 5mm thick, and has a closed-loop circumference of 9.6m (i.e., 4.6m for the upper layer + 4.6m for the lower layer + 0.4m for the arc length of the front and rear rollers).

[0143] The drive roller and guide roller are made of 304 stainless steel, with a diameter of 300mm and a length of 1.8m.

[0144] The material of a single steam heating pipe is 304 stainless steel, with a pipe diameter of 50mm and a wall thickness of 3mm;

[0145] The mist delivery pipe is made of PPR, with a single pipe diameter of 40mm and a length of 4.6m;

[0146] (2) The loose fibers of cellulose material are combed into a weight of 1000 g / m by using a double-air vibration pneumatic cotton box and an airflow web forming machine. 2 Fiber layer;

[0147] (3) The fiber layer is impregnated with indigo leuco dye liquor in a continuous loose fiber dyeing machine with a volume of 100L and a speed of 15m / min; wherein the pick-up rate of the fiber layer impregnated with indigo leuco dye liquor is 100%;

[0148] (4) The impregnated fiber layer is fed into a continuous oxidation reaction chamber at a temperature of 30°C by a crawler conveyor belt. The conveying system will spray the atomized hydrogen peroxide aqueous solution evenly onto the surface of the fiber layer. Then, the atomized hydrogen peroxide aqueous solution will be rapidly adsorbed and penetrated into the cotton fiber layer by a negative pressure filtration system to achieve oxidation and fixation of indigo leuco. After the fiber layer comes out of the continuous oxidation reaction chamber, it will be subjected to deoxygenation water washing, acid washing, soap washing, water washing, drying, and packaging in sequence to complete the dyeing process. The speed of the crawler conveyor belt is 5m / min, the concentration of hydrogen peroxide aqueous solution in the hydrogen peroxide atomizer is 10g / L, the atomization flow rate is 15m / s, the spray volume (i.e. the amount of atomized gas) is 19L / h, the pumping speed of the vacuum pump is 100L / s, and the ultimate vacuum degree is 0.2Pa.

[0149] The spray volume of the above-mentioned conveying system is linked with the negative pressure value of each negative pressure chamber in real time through the PLC system, so that the amount of atomized hydrogen peroxide solution sprayed can be adjusted synchronously with the negative pressure value of each negative pressure chamber, ensuring that the mist penetrates in a directional manner along the three-dimensional direction of "thickness-width-length" under the pressure difference drive, and the middle fiber layer can be almost completely oxidized.

[0150] The core of the PLC system consists of a signal acquisition module, a PLC control center, and an execution drive module, ensuring precise coordination between spray volume and gradient negative pressure value;

[0151] The signal acquisition module includes a spray volume detection unit and a negative pressure detection unit;

[0152] The spray volume detection unit includes a mass flow sensor installed on the hydrogen peroxide mist delivery pipeline, which is used to collect the actual total spray volume data in real time;

[0153] The negative pressure detection unit includes high-precision absolute pressure sensors installed on the branch negative pressure pipes of each gradient negative pressure chamber, which are used to collect the actual negative pressure value of each negative pressure chamber in real time.

[0154] The data acquired by the sensors in the spray volume detection unit and the negative pressure detection unit are all connected to the PLC analog input module to ensure the real-time performance and accuracy of data acquisition;

[0155] The PLC control center includes a built-in linkage control algorithm program that supports preset basic parameters such as "spray volume - negative pressure value", real-time display of operating data (such as current spray volume and negative pressure value of each chamber) and fault alarms.

[0156] The actuation drive module includes an electronic spray volume regulating valve installed on the main outlet pipe of the hydrogen peroxide atomizer and electronic pressure regulating valves installed on the branch pipes of each negative pressure chamber.

[0157] The K / S value of the dyed fiber layer is 13.47, the color difference ΔE is 0.39, the dry rubbing color fastness grade is 4, and the wet rubbing color fastness grade is 3.

[0158] Example 4

[0159] A method for continuous dyeing of loose cellulose fibers with indigo, comprising the following steps:

[0160] (1) Preparation of raw materials and equipment used;

[0161] Cellulose material loose fiber: cotton loose fiber, manufacturer is Aksu Hongxin Cotton Industry Co., Ltd., variety is 65435;

[0162] Dye: Indigo, manufactured by Shanghai Binyou New Material Technology Co., Ltd., brand name: Indigo ID923;

[0163] Sodium dithionite;

[0164] Indigo leuco dye solution: composed of dye at a concentration of 30 g / L, sodium hydrosulfite at a concentration of 50 g / L, sodium hydroxide at a concentration of 30 g / L, and sodium sulfate at a concentration of 60 g / L;

[0165] Continuous oxidation reaction chamber: The above-mentioned continuous oxidation reaction chamber is adopted, wherein the mesh aperture of the nylon mesh conveyor belt is 50mm; there are 5 negative pressure chambers, and along the direction from the drive roller to the guide roller, the mesh aperture of the top of the 5 negative pressure chambers is 5mm, and the pressure values ​​of the 5 negative pressure chambers are -18kPa, -38kPa, -38kPa, -28kPa, and -23kPa, respectively; the gap between the negative pressure chamber and the lower surface of the upper conveyor belt is 2mm; there are 5 steam heating pipes and 5 mist conveying pipes. Each mist conveying pipe is arranged in the shape of multiple non-closed triangles connected together, and each mist conveying pipe has 60 mist nozzles, each mist nozzle has an aperture of 15mm, and the spray angle is 90°;

[0166] The total height of the continuous oxidation reaction chamber is 2.5m, the total length from front to back (i.e., from the front track inlet to the rear track outlet) is 5m, and the total width from left to right is 2.5m.

[0167] The tracked conveyor belt is 1.8m wide, 5mm thick, and has a closed-loop circumference of 9.6m (i.e., 4.6m for the upper layer + 4.6m for the lower layer + 0.4m for the arc length of the front and rear rollers).

[0168] The drive roller and guide roller are made of 304 stainless steel, with a diameter of 300mm and a length of 1.8m.

[0169] The material of a single steam heating pipe is 304 stainless steel, with a pipe diameter of 50mm and a wall thickness of 3mm;

[0170] The mist delivery pipe is made of PPR, with a single pipe diameter of 40mm and a length of 4.6m;

[0171] (2) The loose fibers of cellulose material are combed into a weight of 1200 g / m by using a double-air vibration pneumatic cotton box and an airflow web forming machine. 2 Fiber layer;

[0172] (3) The fiber layer is impregnated with indigo leuco dye liquor in a continuous loose fiber dyeing machine with a volume of 100L and a speed of 10m / min; wherein the pick-up rate of the fiber layer impregnated with indigo leuco dye liquor is 100%;

[0173] (4) The impregnated fiber layer is fed into a continuous oxidation reaction chamber at a temperature of 40°C by a crawler conveyor belt. The conveying system will spray the atomized hydrogen peroxide aqueous solution evenly onto the surface of the fiber layer. Then, the atomized hydrogen peroxide aqueous solution will be rapidly adsorbed and penetrated into the cotton fiber layer by a negative pressure filtration system to achieve oxidation and fixation of indigo leuco. After the fiber layer comes out of the continuous oxidation reaction chamber, it will be subjected to deoxygenation water washing, acid washing, soap washing, water washing, drying, and packaging in sequence to complete the dyeing process. The speed of the crawler conveyor belt is 10 m / min, the concentration of hydrogen peroxide aqueous solution in the hydrogen peroxide atomizer is 40 g / L, the atomization flow rate is 20 m / s, the spray volume (i.e. the amount of atomized gas) is 26 L / h, the pumping speed of the vacuum pump is 100 L / s, and the ultimate vacuum degree is 0.4 Pa.

[0174] The spray volume of the above-mentioned conveying system is linked with the negative pressure value of each negative pressure chamber in real time through the PLC system, so that the amount of atomized hydrogen peroxide solution sprayed can be adjusted synchronously with the negative pressure value of each negative pressure chamber, ensuring that the mist penetrates in a directional manner along the three-dimensional direction of "thickness-width-length" under the pressure difference drive, and the middle fiber layer can be almost completely oxidized.

[0175] The core of the PLC system consists of a signal acquisition module, a PLC control center, and an execution drive module, ensuring precise coordination between spray volume and gradient negative pressure value;

[0176] The signal acquisition module includes a spray volume detection unit and a negative pressure detection unit;

[0177] The spray volume detection unit includes a mass flow sensor installed on the hydrogen peroxide mist delivery pipeline, which is used to collect the actual total spray volume data in real time;

[0178] The negative pressure detection unit includes high-precision absolute pressure sensors installed on the branch negative pressure pipes of each gradient negative pressure chamber, which are used to collect the actual negative pressure value of each negative pressure chamber in real time.

[0179] The data acquired by the sensors in the spray volume detection unit and the negative pressure detection unit are all connected to the PLC analog input module to ensure the real-time performance and accuracy of data acquisition;

[0180] The PLC control center includes a built-in linkage control algorithm program that supports preset basic parameters such as "spray volume - negative pressure value", real-time display of operating data (such as current spray volume and negative pressure value of each chamber) and fault alarms.

[0181] The actuation drive module includes an electronic spray volume regulating valve installed on the main outlet pipe of the hydrogen peroxide atomizer and electronic pressure regulating valves installed on the branch pipes of each negative pressure chamber.

[0182] The K / S value of the dyed fiber layer is 18.4, the color difference ΔE is 0.46, the dry rubbing color fastness grade is 3-4, and the wet rubbing color fastness grade is 3.

[0183] Comparative Example 1

[0184] A method for continuous dyeing of loose cellulose fibers into indigo is basically the same as in Example 4, except that a negative pressure filtration system is not installed below the conveyor belt in the continuous oxidation reaction chamber.

[0185] The final dyed fiber layer has a color difference ΔE of 1.7, a dry rubbing color fastness grade of 2-3, and a wet rubbing color fastness grade of 1.

[0186] Comparing Comparative Example 1 and Example 4, it can be seen that the color difference ΔE of the dyed fibers in this comparative example is larger, and the dry and wet rubbing fastness is reduced to varying degrees. This is because without a negative pressure filtration system, the mist cannot penetrate the fiber layer by relying solely on the gravity sedimentation of the droplets. The penetration depth is less than 1 / 3 of the fiber layer thickness, resulting in a layering phenomenon of "over-oxidation on the upper surface and unoxidation inside". Moreover, during the subsequent multiple water washing, the unoxidized indigo leuco is washed away, which also leads to uneven oxidation of the fiber layer, worsening of the color difference, reduced color yield, and decreased dry and wet rubbing fastness.

[0187] Comparative Example 2

[0188] A method for continuous dyeing of loose cellulose fibers with indigo is basically the same as in Example 4, except that the hydrogen peroxide atomizer in the continuous oxidation reaction chamber does not perform atomization, but directly delivers an aqueous solution of hydrogen peroxide.

[0189] The final color difference ΔE of the dyed fiber layer is 0.9.

[0190] Comparing Comparative Example 2 and Example 4, it can be seen that the color difference ΔE of the dyed fiber in this comparative example is larger. This is because after the loose fiber is impregnated with the indigo leuco solution, it is not oxidized in time. Directly delivering the hydrogen peroxide aqueous solution will wash away most of the unreacted dye solution, resulting in a decrease in the amount of color obtained by the fiber, waste of dye, and a decrease in the fixation rate, which ultimately leads to a larger color difference ΔE.

[0191] Comparative Example 3

[0192] A method for continuous dyeing of loose cellulose fibers with indigo is basically the same as in Example 4, except that the single mist delivery pipe in the continuous oxidation reaction chamber is straight.

[0193] The final dyed fiber layer has a color difference ΔE of 0.8, a dry rubbing color fastness grade of 3, and a wet rubbing color fastness grade of 1.

[0194] Comparing Comparative Example 3 and Example 4, it can be seen that the color difference ΔE of the dyed fibers in this comparative example is larger, and the dry and wet rubbing fastness is reduced to varying degrees. This is because there is a certain blind zone in the spray coverage, and the droplets move in parallel directions, making it difficult to form a cross-penetration flow field. The straight pipe, due to the consistent spray direction, results in a distribution defect of "concentrated in the middle and light on both sides", which destroys the oxidation uniformity. The unoxidized indigo leuco is washed away, and the other part remains on the fiber surface after oxidation, ultimately leading to a larger color difference ΔE and a reduced dry and wet rubbing fastness.

[0195] Example 5

[0196] A method for continuous dyeing of loose cellulose fibers with indigo, comprising the following steps:

[0197] (1) Preparation of raw materials and equipment used;

[0198] Cellulose material loose fiber: viscose loose fiber, manufactured by Tangshan Sanyou Group, specification 1.1dtex;

[0199] Dye: Indigo, manufactured by Shanghai Binyou New Material Technology Co., Ltd., brand name: Indigo ID923;

[0200] Sodium dithionite;

[0201] Indigo leuco dye solution: composed of dye at a concentration of 30 g / L, sodium hydrosulfite at a concentration of 50 g / L, sodium hydroxide at a concentration of 30 g / L, and sodium sulfate at a concentration of 60 g / L;

[0202] Continuous oxidation reaction chamber: The above-mentioned continuous oxidation reaction chamber is adopted, wherein the mesh aperture of the nylon mesh conveyor belt is 50mm; there are 5 negative pressure chambers, and along the direction from the drive roller to the guide roller, the mesh aperture of the top of the 5 negative pressure chambers is 5mm, and the pressure values ​​of the 5 negative pressure chambers are -18kPa, -38kPa, -38kPa, -28kPa, and -23kPa, respectively; the gap between the negative pressure chamber and the lower surface of the upper conveyor belt is 2mm; there are 5 steam heating pipes and 5 mist conveying pipes. The shape of each mist conveying pipe is serrated, and each mist conveying pipe has 60 mist nozzles, each mist nozzle has an aperture of 15mm, and the spray angle is 90°;

[0203] The total height of the continuous oxidation reaction chamber is 2.5m, the total length from front to back (i.e., from the front track inlet to the rear track outlet) is 5m, and the total width from left to right is 2.5m.

[0204] The tracked conveyor belt is 1.8m wide, 5mm thick, and has a closed-loop circumference of 9.6m (i.e., 4.6m for the upper layer + 4.6m for the lower layer + 0.4m for the arc length of the front and rear rollers).

[0205] The drive roller and guide roller are made of 304 stainless steel, with a diameter of 300mm and a length of 1.8m.

[0206] The material of a single steam heating pipe is 304 stainless steel, with a pipe diameter of 50mm and a wall thickness of 3mm;

[0207] The mist delivery pipe is made of PPR, with a single pipe diameter of 40mm and a length of 4.6m;

[0208] (2) The loose fibers of cellulose material are combed into a weight of 1200 g / m by using a double-air vibration pneumatic cotton box and an airflow web forming machine. 2 Fiber layer;

[0209] (3) The fiber layer is impregnated with indigo leuco dye liquor in a continuous loose fiber dyeing machine with a volume of 100L and a speed of 10m / min; wherein, the pick-up rate of the fiber layer impregnated with indigo leuco dye liquor is 90%;

[0210] (4) The impregnated fiber layer is fed into a continuous oxidation reaction chamber at a temperature of 40°C by a crawler conveyor belt. The conveying system will spray the atomized hydrogen peroxide aqueous solution evenly onto the surface of the fiber layer. Then, the atomized hydrogen peroxide aqueous solution will be rapidly adsorbed and penetrated into the cotton fiber layer by a negative pressure filtration system to achieve oxidation and fixation of indigo leuco. After the fiber layer comes out of the continuous oxidation reaction chamber, it will be subjected to deoxygenation water washing, acid washing, soap washing, water washing, drying, and packaging in sequence to complete the dyeing process. The speed of the crawler conveyor belt is 2m / min, the concentration of hydrogen peroxide aqueous solution in the hydrogen peroxide atomizer is 40g / L, the atomization flow rate is 20m / s, the spray volume (i.e. the amount of atomized gas) is 26L / h, the pumping speed of the vacuum pump is 100L / s, and the ultimate vacuum degree is 0.4Pa.

[0211] The spray volume of the above-mentioned conveying system is linked with the negative pressure value of each negative pressure chamber in real time through the PLC system, so that the amount of atomized hydrogen peroxide solution sprayed can be adjusted synchronously with the negative pressure value of each negative pressure chamber, ensuring that the mist penetrates in a directional manner along the three-dimensional direction of "thickness-width-length" under the pressure difference drive, and the middle fiber layer can be almost completely oxidized.

[0212] The core of the PLC system consists of a signal acquisition module, a PLC control center, and an execution drive module, ensuring precise coordination between spray volume and gradient negative pressure value;

[0213] The signal acquisition module includes a spray volume detection unit and a negative pressure detection unit;

[0214] The spray volume detection unit includes a mass flow sensor installed on the hydrogen peroxide mist delivery pipeline, which is used to collect the actual total spray volume data in real time;

[0215] The negative pressure detection unit includes high-precision absolute pressure sensors installed on the branch negative pressure pipes of each gradient negative pressure chamber, which are used to collect the actual negative pressure value of each negative pressure chamber in real time.

[0216] The data acquired by the sensors in the spray volume detection unit and the negative pressure detection unit are all connected to the PLC analog input module to ensure the real-time performance and accuracy of data acquisition;

[0217] The PLC control center includes a built-in linkage control algorithm program that supports preset basic parameters such as "spray volume - negative pressure value", real-time display of operating data (such as current spray volume and negative pressure value of each chamber) and fault alarms.

[0218] The actuation drive module includes an electronic spray volume regulating valve installed on the main outlet pipe of the hydrogen peroxide atomizer and electronic pressure regulating valves installed on the branch pipes of each negative pressure chamber.

[0219] The K / S value of the dyed fiber layer is 16.75, the color difference ΔE is 0.35, the dry rubbing color fastness grade is 3-4, and the wet rubbing color fastness grade is 3.

[0220] Example 6

[0221] A method for continuous dyeing of loose cellulose fibers with indigo, comprising the following steps:

[0222] (1) Preparation of raw materials and equipment used;

[0223] Cellulose material loose fiber: Modal loose fiber, manufactured by Tangshan Sanyou Group, brand name Tangsi® Modal;

[0224] Dye: Indigo, manufactured by Shanghai Binyou New Material Technology Co., Ltd., brand name: Indigo ID923;

[0225] Sodium dithionite;

[0226] Indigo leuco dye solution: composed of dye at a concentration of 30 g / L, sodium hydrosulfite at a concentration of 50 g / L, sodium hydroxide at a concentration of 30 g / L, and sodium sulfate at a concentration of 60 g / L;

[0227] Continuous oxidation reaction chamber: The above-mentioned continuous oxidation reaction chamber is adopted, wherein the mesh aperture of the nylon mesh conveyor belt is 50mm; there are 5 negative pressure chambers, and along the direction from the drive roller to the guide roller, the mesh aperture of the top of the 5 negative pressure chambers is 5mm, and the pressure values ​​of the 5 negative pressure chambers are -18kPa, -38kPa, -38kPa, -28kPa, and -23kPa, respectively; the gap between the negative pressure chamber and the lower surface of the upper conveyor belt is 2mm; there are 5 steam heating pipes and 5 mist conveying pipes. The shape of each mist conveying pipe is serrated, and each mist conveying pipe has 60 mist nozzles, each mist nozzle has an aperture of 15mm, and the spray angle is 90°;

[0228] The total height of the continuous oxidation reaction chamber is 2.5m, the total length from front to back (i.e., from the front track inlet to the rear track outlet) is 5m, and the total width from left to right is 2.5m.

[0229] The tracked conveyor belt is 1.8m wide, 5mm thick, and has a closed-loop circumference of 9.6m (i.e., 4.6m for the upper layer + 4.6m for the lower layer + 0.4m for the arc length of the front and rear rollers).

[0230] The drive roller and guide roller are made of 304 stainless steel, with a diameter of 300mm and a length of 1.8m.

[0231] The material of a single steam heating pipe is 304 stainless steel, with a pipe diameter of 50mm and a wall thickness of 3mm;

[0232] The mist delivery pipe is made of PPR, with a single pipe diameter of 40mm and a length of 4.6m;

[0233] (2) The loose fibers of cellulose material are combed into a weight of 1200 g / m by using a double-air vibration pneumatic cotton box and an airflow web forming machine. 2 Fiber layer;

[0234] (3) The fiber layer is impregnated with indigo leuco dye liquor in a continuous loose fiber dyeing machine with a volume of 100L and a speed of 10m / min; wherein, the pick-up rate of the fiber layer impregnated with indigo leuco dye liquor is 110%;

[0235] (4) The impregnated fiber layer is fed into a continuous oxidation reaction chamber at a temperature of 40°C by a crawler conveyor belt. The conveying system will spray the atomized hydrogen peroxide aqueous solution evenly onto the surface of the fiber layer. Then, the atomized hydrogen peroxide aqueous solution will be rapidly adsorbed and penetrated into the cotton fiber layer by a negative pressure filtration system to achieve oxidation and fixation of indigo leuco. After the fiber layer comes out of the continuous oxidation reaction chamber, it will be deoxygenated, acid washed, soaped, washed, dried, and packaged in sequence to complete the dyeing process. The speed of the crawler conveyor belt is 15 m / min, the concentration of hydrogen peroxide aqueous solution in the hydrogen peroxide atomizer is 40 g / L, the atomization flow rate is 20 m / s, the spray volume (i.e. the amount of atomized gas) is 26 L / h, the pumping speed of the vacuum pump is 100 L / s, and the ultimate vacuum degree is 0.4 Pa.

[0236] The spray volume of the above-mentioned conveying system is linked with the negative pressure value of each negative pressure chamber in real time through the PLC system, so that the amount of atomized hydrogen peroxide solution sprayed can be adjusted synchronously with the negative pressure value of each negative pressure chamber, ensuring that the mist penetrates in a directional manner along the three-dimensional direction of "thickness-width-length" under the pressure difference drive, and the middle fiber layer can be almost completely oxidized.

[0237] The core of the PLC system consists of a signal acquisition module, a PLC control center, and an execution drive module, ensuring precise coordination between spray volume and gradient negative pressure value;

[0238] The signal acquisition module includes a spray volume detection unit and a negative pressure detection unit;

[0239] The spray volume detection unit includes a mass flow sensor installed on the hydrogen peroxide mist delivery pipeline, which is used to collect the actual total spray volume data in real time;

[0240] The negative pressure detection unit includes high-precision absolute pressure sensors installed on the branch negative pressure pipes of each gradient negative pressure chamber, which are used to collect the actual negative pressure value of each negative pressure chamber in real time.

[0241] The data acquired by the sensors in the spray volume detection unit and the negative pressure detection unit are all connected to the PLC analog input module to ensure the real-time performance and accuracy of data acquisition;

[0242] The PLC control center includes a built-in linkage control algorithm program that supports preset basic parameters such as "spray volume - negative pressure value", real-time display of operating data (such as current spray volume and negative pressure value of each chamber) and fault alarms.

[0243] The actuation drive module includes an electronic spray volume regulating valve installed on the main outlet pipe of the hydrogen peroxide atomizer and electronic pressure regulating valves installed on the branch pipes of each negative pressure chamber.

[0244] The K / S value of the dyed fiber layer is 20.56, the color difference ΔE is 0.41, the dry rubbing color fastness grade is 3, and the wet rubbing color fastness grade is 2-3.

Claims

1. A method for continuous dyeing of loose cellulose fibers with indigo, characterized in that: Cellulose loose fibers are combed into fiber layers by a web forming machine. After the fiber layers are immersed in indigo leuco dyeing solution by a continuous loose fiber dyeing machine, they are sent to a continuous oxidation reaction chamber. In the continuous oxidation reaction chamber, the indigo leuco dyeing is oxidized and fixed, thus completing the dyeing process. The continuous oxidation reaction chamber includes a cuboid chamber and a conveying system, a reaction supply system, and a negative pressure filtration system located inside the chamber; The conveying system is located below the reaction supply system and runs through the front and rear ends along the length of the container. The conveying system includes a tracked conveyor belt, which is a nylon mesh conveyor belt. The negative pressure filtration system includes negative pressure chambers and a vacuum pump. There are three or more negative pressure chambers, which are located between the upper and lower tracks of the conveyor belt and close to the lower surface of the upper track. The vacuum pump is located at the rear end of the housing. All negative pressure chambers are connected to the vacuum pump through pipelines, and a pressure regulating valve is installed on the pipeline near each negative pressure chamber. Along the fiber layer conveying direction, the pressure of the middle negative pressure chamber is greater than the pressure of the rear negative pressure chamber, which is greater than the pressure of the front negative pressure chamber. The reaction supply system is located above the conveying system. From top to bottom, the reaction supply system includes a temperature control unit and an oxidation medium supply unit. The oxidation medium supply unit includes a hydrogen peroxide atomizer, a mist delivery pipe, and mist nozzles evenly arranged on the mist delivery pipe. The hydrogen peroxide atomizer is located at the rear end of the chamber and above the vacuum pump. There are 3 to 10 mist delivery pipes. The hydrogen peroxide atomizer is connected to all the mist delivery pipes. A single mist delivery pipe is serrated or arranged in multiple non-closed triangles. The extension direction of the mist delivery pipe is the width direction of the chamber. All the mist delivery pipes are alternately offset by 50 to 100 mm in the width direction of the chamber.

2. The method for continuous dyeing of loose cellulose fibers with indigo according to claim 1, characterized in that, The conveying system also includes a drive roller at the front end of the crawler conveyor belt and a guide roller at the rear end; the surface of the drive roller is covered with a rubber anti-slip layer, and the two ends of the roller shaft are fixed to the inner walls on both sides of the box width direction by bearings, and one end is connected to a geared motor; the two ends of the guide roller are fixed to the inner walls on both sides of the box width direction by bearings, and the guide roller and the drive roller have the same diameter and length, and the roller shafts are parallel and at the same height.

3. The method for continuous dyeing of loose indigo fibers from cellulose material according to claim 1, characterized in that, The aperture of the mesh hole in the tracked conveyor belt is 10~70mm; The top of the negative pressure chamber is made of stainless steel mesh with a mesh size of 3~5mm, and the bottom is a negative pressure interface with a diameter of 50mm; The gap between the negative pressure chamber and the lower surface of the upper track is ≤3mm.

4. The method for continuous dyeing of loose indigo fibers from cellulose material according to claim 1, characterized in that, The temperature control unit includes 3 to 10 steam heating pipes evenly distributed along the length of the chamber, with each pair of adjacent steam heating pipes connected to each other in a U-shape at one end.

5. The method for continuous dyeing of loose cellulose fibers with indigo according to claim 4, characterized in that, The steam heating pipes, mist conveying pipes, and mist nozzles are all wrapped in an insulation layer made of flame-retardant rock wool.

6. The method for continuous dyeing of loose indigo fibers from cellulose material according to claim 4, characterized in that, The temperature control unit also includes a temperature sensing switch, which is located at the air inlet of the steam heating pipe and is used to control the internal temperature of the continuous oxidation reaction chamber. The temperature inside the continuous oxidation reaction chamber is 20~80℃.

7. The method for continuous dyeing of loose cellulose fibers with indigo according to claim 1, characterized in that, Each mist delivery pipe has 10 to 100 mist nozzles, each with a diameter of 10 to 20 mm. The mist emitted from each nozzle is fan-shaped with a spray angle of 30° to 165°. All mist nozzles face the same direction.

8. The method for continuous dyeing of loose indigo fibers from cellulose material according to claim 1, characterized in that, The loose fibers of cellulose material are cotton loose fibers, viscose loose fibers, or modal loose fibers; The loose cellulose fibers are combed into fiber layers using a dual-air vibration pneumatic cotton box and an airflow web forming machine, with a fiber layer weight of 500~2500 g / m². 2 ; The continuous loose fiber dyeing machine has a speed of 2~15m / min and a volume of 50~200L.

9. The method for continuous dyeing of loose indigo fibers from cellulose material according to claim 1, characterized in that, In the indigo leuco dyeing solution, the concentration of dye is 1~100g / L, the concentration of sodium hydrosulfite is 5~80g / L, the concentration of sodium hydroxide is 5~60g / L, and the concentration of sodium sulfate is 10~100g / L; The fiber layer is impregnated with indigo leuco dye liquor, with a pick-up rate of 60-130%; the speed of the conveyor belt is 2-15 m / min.

10. The method for continuous dyeing of loose indigo fibers from cellulose material according to claim 1, characterized in that, The concentration of hydrogen peroxide solution in the hydrogen peroxide atomizer is 1~50g / L; the pumping speed of the vacuum pump is 100L / s, and the ultimate vacuum degree is ≤1Pa; the atomized gas flow rate is 15~30m / s.

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