Gradient-color velvet spinning process

Abstract

The invention relates to the technical field of spinning, and particularly discloses a gradient velvet spinning process which comprises the following steps: S1, immersing velvet fibers into a pretreatment solution containing 3.5-4.2 wt% of sodium citrate, and carrying out ultrasonic cleaning at 32 + / -0.5 DEG C for 12 minutes under the ultrasonic frequency of 40kHz and the amplitude controlled to be 1.2-1.5 times of the diameter of the fibers; s2, the pretreated fibers are placed in a dyeing tank, gradient heating is conducted, dye liquor is injected synchronously, and the flow speed of the dye liquor is controlled to be opposite to the fiber movement direction; s3, after the dye liquor is discharged, a color fixing agent is injected, and treatment is conducted for 20 min in a 50 DEG C vortex field; s4, the color fixing fibers are guided into a spinning machine, the spindle speed is 9000-12000rpm, and the winding ratio is 1: 4.2. By means of the spinning process, high-quality velvet with the color fastness larger than or equal to 5 levels and the fluctuation ratio of a gradual transition area smaller than or equal to 6.8% can be obtained, and the risks that the hue is out of control and the fastness is insufficient are avoided.

Description

Technical Field

[0001] The present application relates to the technical field of spinning, and more particularly, to a gradient color velvet spinning process. Background Art

[0002] The spinning process is the process of converting natural fibers or chemical fibers into yarns through a series of processing steps. Its core is to put the loose fiber raw materials through the main links of opening, carding, drawing, roving, spinning, etc. to achieve fiber purification, straightening, parallelization, drafting and twisting, and finally form yarns with certain strength, fineness and uniformity. This process requires adjusting the process parameters according to the fiber characteristics and yarn usage. Chemical fiber spinning is often combined with melt spinning and other technologies to improve production efficiency. The quality of the spinning process directly affects the product quality of subsequent weaving, dyeing and finishing links.

[0003] The related spinning process adopts the same-direction dyeing method and carries out a three-stage separation process of dyeing, fixing and drawing to obtain velvet yarn. However, in this process, the dye solution and the fiber flow in the same direction, resulting in an insufficient probability of dye collision, and the use of mordants such as alum will generate Al(OH)3 colloidal precipitation when the pH is greater than 5.0, resulting in high volatility of the color gradient area and low color fastness. Summary of the Invention

[0004] In order to solve the problem of high color fluctuation and low color fastness in the color gradient area caused by the use of the same-direction dyeing method in the relevant spinning process, the present application provides a gradient color velvet spinning process.

[0005] In the first aspect, the present application provides a gradient color velvet spinning process, which adopts the following technical solutions:

[0006] The gradient color velvet spinning process includes the following steps:

[0007] S1. Fiber pretreatment: immerse the velvet fiber in a pretreatment solution containing 3.5-4.2 wt% sodium citrate, and ultrasonically clean it at 32±0.5°C for 12 min, with an ultrasonic frequency of 40 kHz and an amplitude controlled at 1.2-1.5 times the fiber diameter;

[0008] S2. Gradient dyeing: Place the pretreated fiber in a dyeing tank, increase the temperature to 65°C at a gradient of 1.2°C / min, and simultaneously inject a dye solution composed of the following parts by weight:

[0009] 15-22 parts of cationic dye,

[0010] Rare earth mordant LaCl 3: 0.8~1.5 parts,

[0011] 2-3 parts of pH buffer,

[0012] 1000 parts of deionized water,

[0013] Among them, the dye liquor flow rate is controlled in the opposite direction to the fiber movement direction, and the flow rate difference is 0.8-1.3 m / s;

[0014] S3. Color fixation and strengthening: After draining the dye liquor, inject the color fixing agent and treat in a 50℃ eddy current field for 20 minutes. The eddy current intensity and fiber linear density satisfy the relationship: Ψ=0.07ρ+3.2, where Ψ is the eddy current speed / rpm and ρ is the fiber linear density / dtex;

[0015] S4. Spinning: The fixed color fiber is introduced into the spinning machine with a drafting force of 0.6-0.9N / tex, a spindle speed of 9000-12000rpm, and a winding ratio of 1:4.2.

[0016] By adopting the above technical solution, velvet fibers are longitudinally arranged and immersed in a pretreatment liquid containing 3.5-4.2wt% sodium citrate, and the temperature is controlled in a constant temperature water bath within the range of 32°C ± 0.5°C; an ultrasonic generator is activated to cause the pretreatment liquid to form periodic compression and expansion. At this time, the ultrasonic amplitude is calibrated to a range of 1.2-1.5 times the fiber diameter. The amplitude selection is based on the balance between the fiber breaking strength and the cavitation effect threshold. Excessive amplitude will cause micro-damage to the fiber surface, while too low amplitude cannot effectively strip the hydrophobic film on the fiber surface; after 12 minutes of continuous treatment, uniform hydroxylation active sites are formed on the fiber surface. This activated state provides conditions for subsequent dye adsorption;

[0017] The pretreated fibers are then transferred to the dyeing tank, where they are directed at a linear speed of 0.8 M / s by electric guide rollers. Simultaneously, a metering pump injects a preset dye solution, with the mass ratio of red and blue dyes locked at 1.2±0.1. This ratio, as verified by a colorimetric model, can achieve a gradient spectrum coverage from violet to burgundy. The dye delivery pipeline is arranged 180 degrees in the opposite direction of fiber movement, and the dye flow rate is controlled to be 0.8-1.3 M / s higher than the fiber movement speed. This reverse flow rate difference increases the probability of collision between dye molecules and fiber active sites by 2.3 times. The dye tank temperature is raised in a stepwise manner. From 40 to 50°C, a slow rise rate of 0.8°C / min is used to fully swell the fibers. From 50 to 60°C, the speed is increased to 1.5°C / min to promote dye diffusion. From 60 to 65°C, the speed is reduced to 0.5°C / min to complete molecular orientation fixation.

[0018] After dyeing is completed, the valve is switched to discharge the dye liquor and a fixing agent containing a quaternary ammonium salt cationic polymer is injected, with a molecular weight distribution index of no more than 1.3. The vortex generator is started and the rotation speed Ψ is dynamically adjusted according to the fiber linear density ρ. The quantitative relationship between the two follows the formula Ψ = 0.07ρ + 3.2 to ensure that the fixing agent forms a nano-scale coating film on the fiber surface.

[0019] Finally, the fixed-color fiber is introduced into the ring spinning machine, and the drafting roller applies a tension of 0.6 to 0.9 N / tex. This tension range is determined by the material yield strength test to be 72%-85% of the critical value of fiber plastic deformation; the spindle speed is set to 9000-12000 rpm, and the winding ratio is 1:4.2. This parameter combination makes the yarn twist gradient and the dyeing gradient form a spatial match, and finally produces velvet yarn with a color fastness of more than level 5 and a gradient transition zone length fluctuation rate of no more than 8%.

[0020] Preferably, in step S1, 0.5 parts of a fiber swelling promoter is added to the pretreatment liquid, and the structural formula thereof is C 12 H 25 O-(CH2CH2O)3-SO3Na.

[0021] By adopting the above technical solution, when preparing the pretreatment solution, a fiber swelling promoter is quantitatively added to the solution containing sodium citrate. The molecular structure of the promoter consists of a dodecyl chain connected by an ether bond to three ethylene oxide units, with a sodium sulfonate group grafted to the end. The addition amount of the promoter is controlled at 0.5 parts by weight. This concentration can reduce the contact angle of velvet fiber from the original value of 103° to 38° as measured by the capillary rise method, proving that the promoter can improve the permeability of the solution.

[0022] The mechanism of action of the swelling promoter is divided into three stages: first, the alkyl chain is embedded in the hydrophobic area of ​​the fiber surface, destroying the hydrogen bond network through van der Waals force; then the polyethylene oxide chain forms a hydrogen bond complex with water molecules, inducing the expansion of the micro-voids in the amorphous area of ​​the fiber; the electrostatic repulsion generated by the terminal sulfonic acid group increases the fiber porosity; this process continues at a constant temperature of 32°C, and it is confirmed by electron microscopy observation of the fiber cross-section that the diameter increases after swelling, establishing a through channel with a diameter of 2-5nm for the subsequent diffusion of dye molecules.

[0023] Preferably, the S2 gradient heating is divided into three stages:

[0024] 40-50℃ stage: heating rate 0.8℃ / min,

[0025] 50-60℃ stage: heating rate 1.5℃ / min,

[0026] 60-65℃ stage: heating rate 0.5℃ / min.

[0027] By adopting the above technical solution, the programmed temperature rising device is started and the initial temperature of the dyeing tank is set to 40°C; in the first stage of heating to 50°C, a heating rate of 0.8°C per minute is adopted. This rate is calculated and verified by Fick's second law and matches the glass transition temperature of the amorphous region of the fiber. At this time, the expansion rate of the microporous channel inside the fiber is 0.12μm / min, ensuring that the dye enters the fiber cross section evenly by capillary penetration; after maintaining this rate for a period of time, the platinum resistance temperature sensor feedback confirms that the tank temperature has reached 50°C; then it switches to heating. In the second stage, the rate was increased to 1.5°C / min. At this rate, the deorientation rate of the edge of the fiber crystallization zone and the rotational diffusion rate of the cationic dye molecules reached a dynamic equilibrium. The heating process continued to the target temperature of 60°C, at which time the fiber swelling rate reached a peak of 62±3%; in the final stage, the temperature was raised to 65°C at a rate of 0.5°C / min. At this rate, the relaxation time of the fiber macromolecular segment movement was 120 seconds, allowing the rare earth-dye complex adsorbed on the fiber to complete conformational rearrangement, and differential scanning calorimetry was used to confirm that there was no local overheating during the heating process in this stage.

[0028] Preferably, in step S2, the pH value of the dye solution is controlled at 4.5±0.2 by using a citric acid-sodium citrate buffer system.

[0029] By adopting the above technical solution, when preparing the dye solution, the operator weighs citric acid and sodium citrate in a molar ratio of 1:1.72. The ratio is calculated according to the following formula: pH = pKa2 + log ([A - ] / [HA]), where the secondary ionization constant of citric acid, pKa2, is 4.76, measured at 25°C. To achieve the target pH of 4.5, [hydrogen citrate] / [citric acid] is inversely deduced to be 0.55. The buffering mechanism of citric acid-sodium citrate is as follows: hydrogen citrate consumes free hydrogen ions in the dye solution, sodium ions maintain the solution ionic strength at 0.15±0.01M, and undissociated citric acid molecules chelate heavy metal ions.

[0030] By maintaining a constant pH value, the quaternary ammonium group of the cationic dye X-GRL molecule is kept in an ionized state, so that the Zeta potential of the dye remains constant; secondly, it can ensure that the rare earth lanthanum ion is La(H2O)7 3+ If the pH is lower than 4.0, it forms La(OH) 2+ The results show that the cleavage rate of glucosidic bonds on the fiber surface at pH 4.5 is 0.03 μmol / (g·h), which is 15 times lower than that at pH 3.5, further inhibiting the hydrolysis of ester bonds of cellulose fibers.

[0031] Preferably, the color fixing agent in step S3 is a quaternary ammonium salt cationic polymer, and its molecular weight distribution PDI is ≤1.3.

[0032] By adopting the above technical solution, a copolymer of dimethyldiallylammonium chloride and acrylamide is selected as a quaternary ammonium salt-type color fixing agent. The polymer is synthesized by a reversible addition-fragmentation chain transfer polymerization process. During the reaction, 4-cyano-4-[(dodecylsulfonylthio)thio]pentanoic acid is used as a chain transfer agent, the total monomer concentration is controlled to 28wt%, and the reaction is then constant-temperature reacted at 65°C for 12 hours. After synthesis, the product is purified using an ultrafiltration membrane package to ultimately obtain a product with a molecular weight distribution index (PDI) of 1.28±0.02. The PDI value is measured by gel permeation chromatography using a 0.1 mol / L sodium nitrate solution as the mobile phase. A PDI of ≤1.3 ensures that the hydrodynamic diameter distribution dispersion coefficient of the polymer in the 50°C eddy flow field in step S3 is ≤15%, thereby enabling the color fixing agent molecules to form a monomolecular adsorption layer with a thickness of 8.2±0.7 nm on the fiber surface.

[0033] Preferably, in the step S4, atomized lubricant is applied to the fiber before spinning, wherein the atomized particle size is controlled at 10-15 μm and the applied amount is 0.2 g / tex.

[0034] By adopting the above technical scheme, polyether-modified silicone and barium stearate are first compounded in a mass ratio of 4:1 to form a lubricant mother liquor, and then the mother liquor is kept warm and stirred in a constant temperature bath at 55±0.5℃ until the viscosity reaches 120±5mPa·s; a compressed air pressure of 0.15MPa is applied through a dual-fluid atomizing nozzle, and the liquid flow rate is adjusted to 0.8L / h, so that the atomized particle size distribution is concentrated in the range of 10-15μm, thereby forming monodisperse droplets; at the same time, under the action of the drafting roller, the lubricant forms an oil film on the surface of the fiber after S3 fixation treatment; the polyether chain segment of the lubricant adsorbs the carboxyl group on the fiber surface to form hydrogen bonds, and the methylsiloxane chain is arranged in a direction to reduce the friction coefficient. At the same time, the barium ions generated by the decomposition of barium stearate can neutralize the residual static charge of the fiber.

[0035] Preferably, in step S2, 0.05 parts of a defoaming agent is added to the dye solution, which is a polydimethylsiloxane-silicon dioxide composite.

[0036] By adopting the above technical solution, polydimethylsiloxane and hydrophobic fumed silica are first premixed in a mass ratio of 9:1, and treated three times in a three-roll mill with a roller gap pressure of 0.25 MPa and a roller speed ratio of 1:3:9 to prepare a composite defoamer; before the dye liquor is injected in step S2, the composite defoamer is added to the circulation pipeline via a metering pump at a basis of 0.05 parts per 1000 parts of the dye liquor; the hydrophobic silica particles puncture the bubble film on the surface of the dye liquor to accelerate the drainage of the liquid film, thereby improving the defoaming efficiency.

[0037] In the second aspect, the present application provides gradient velvet, which adopts the following technical solutions:

[0038] Gradient color velvet, comprising the following components in parts by weight:

[0039] Cationic Red X-GRL: 8-12 parts,

[0040] Cationic blue YB: 7-10 parts,

[0041] Rare earth mordant LaCl3: 0.8-1.5 parts,

[0042] Citric acid-sodium citrate buffer: 2-3 parts,

[0043] Fiber swelling promoter: 1.8 parts,

[0044] Deionized water: 1000 parts;

[0045] The component content must meet the following requirements: cationic red X-GRL / cationic blue YB = 1.2 ± 0.1;

[0046] By adopting the above technical scheme, 10.0±0.5 parts of cationic red X-GRL dye and 8.3±0.4 parts of cationic blue YB dye were first weighed, and the mass ratio of the two was controlled to be 1.2±0.1. If the red-blue ratio is 1.2, the main wavelength of 583nm corresponds to a violet hue. Deviating from this ratio by ±0.15 will result in a hue angle shift of more than 8°. Then, 1.15 parts of rare earth lanthanum chloride was added, which dissociated into La(H2O)n in the dye solution. 3+ and forms a coordination bond with the dye sulfonate group through an empty orbital. X-ray photoelectron spectroscopy confirms that the decomposition temperature of the dye increases.

[0047] The buffer is a compound of citric acid monohydrate and sodium citrate dihydrate to ensure that the pH of S2 is 4.5±0.2 throughout the entire gradient heating process; the fiber swelling promoter contains sodium alkyl polyoxyethylene ether sulfate and cocamidopropyl betaine. The combination of the two reduces the surface tension of the solution and thus reduces the fiber contact angle. At this time, the spreading rate of the dye solution on the fiber surface is improved, and the time for the fiber to be completely wetted is shortened.

[0048] Preferably, the fiber swelling promoter comprises 80 wt % of alkyl polyoxyethylene ether sulfate and 20 wt % of cocamidopropyl betaine.

[0049] By adopting the above technical scheme, alkyl polyoxyethylene ether sulfate and cocamidopropyl betaine are weighed and premixed in a mass ratio of 4:1, wherein the alkyl polyoxyethylene ether sulfate provides a hydrophobic alkyl chain embedded in the amorphous region of the fiber, and the amide group of cocamidopropyl betaine forms a double hydrogen bond with the fiber hydroxyl group; the composite system reduces the surface tension of the solution in a 32°C pretreatment liquid, thereby reducing the contact angle of the velvet fiber. At this time, the spreading rate of the dye solution on the fiber surface is improved, and ultimately the time for the fiber to be completely wetted is shortened, saving the amount of dye.

[0050] Preferably, the color fastness of the gradient velvet is ≥ level 5.

[0051] By adopting the above technical solution, the rare earth mordant La 3+ It forms a coordination bond with the sulfonic acid group of the dye, and the narrow molecular weight distribution of the quaternary ammonium salt cationic polymer PDI≤1.3 enables it to form a coating layer with low thickness fluctuation; the composite structure has been tested by GB / T3920-2008 friction test, and the grayscale level change ΔL*≤2.3 after 100 dry rubbings / 20 wet rubbings, meeting the level 5 standard.

[0052] In summary, this application has the following beneficial effects:

[0053] 1. Since this application adopts a synergistic process of gradient dyeing and eddy current fixation, by controlling the reverse flow velocity difference of the dye solution and the staged heating program, the probability of dye molecules colliding at the active sites of the fiber is increased. At the same time, the rare earth mordant LaCl3 forms a stable complex under pH 4.5±0.2, and finally obtains high-quality velvet with color fastness ≥ level 5 and gradient transition zone fluctuation rate ≤6.8%, avoiding the risk of hue loss of control and insufficient fastness.

[0054] 2. In this application, an alkyl polyoxyethylene ether composite swelling agent is preferably used because its molecular structure can directionally destroy the hydrogen bond network of the fiber. Contact angle test and electron microscopy observation confirm that 2-5nm through-hole channels are formed, which improves the utilization rate of the dye. At the same time, the ultrasonic amplitude is limited to 1.2-1.5 times the fiber diameter, avoiding the risk of micro-damage when the amplitude is greater than 1.5 times.

[0055] 3. The spinning forming method of the present application controls the eddy current speed and combines the critical plastic tension of 0.6 to 0.9 N / tex with a narrow distribution color fixing agent with PDI ≤ 1.3, so that the quaternary ammonium salt polymer forms a homogeneous coating layer. At the same time, the barium stearate component of the atomized lubricant neutralizes static electricity, thereby achieving zero-breakage spinning at a fixed winding ratio, thereby improving production efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0056] Figure 1 This is a schematic diagram of the process of the gradient color velvet spinning process proposed in this application; DETAILED DESCRIPTION

[0057] The present application is further described in detail below with reference to the accompanying drawings and examples.

[0058] The related spinning process adopts the same-direction dyeing method and carries out a three-stage separation process of dyeing, fixing and drawing to obtain velvet yarn. However, in this process, the dye solution and the fiber flow in the same direction, resulting in an insufficient probability of dye collision, and the use of mordants such as alum will generate Al(OH)3 colloidal precipitation when the pH is greater than 5.0, resulting in high volatility of the color gradient area and low color fastness.

[0059] The present application discloses a gradient color velvet spinning process, comprising the following steps: S1: immersing the velvet fiber in a pretreatment solution containing 3.5-4.2wt% sodium citrate, ultrasonically cleaning the velvet fiber at 32±0.5°C for 12 min, with an ultrasonic frequency of 40kHz and an amplitude controlled at 1.2-1.5 times the fiber diameter; S2: placing the pretreated fiber in a dyeing tank, gradually increasing the temperature, and synchronously injecting the dye solution, controlling the dye solution flow rate to be opposite to the fiber movement direction; S3: injecting a color fixing agent after discharging the dye solution, and treating the fiber in a 50°C eddy current field for 20 min; S4: introducing the color-fixing fiber into a spinning machine with a spindle speed of 9000-12000rpm and a winding ratio of 1:4.2.

[0060] This application adopts a collaborative process of gradient dyeing and eddy current fixation. By controlling the reverse flow velocity difference of the dye solution and the segmented heating program, the probability of dye molecules colliding at the active sites of the fiber is increased. At the same time, the rare earth mordant LaCl3 forms a stable complex under pH 4.5±0.2 conditions, and finally obtains high-quality velvet with color fastness ≥ level 5 and gradient transition zone fluctuation rate ≤6.8%, avoiding the risk of hue loss of control and insufficient fastness.

[0061] Example 1

[0062] This embodiment provides a gradient color velvet spinning process, comprising the following steps:

[0063] S1. Fiber pretreatment:

[0064] The velvet fibers were immersed in a pretreatment solution containing 3.5 wt% sodium citrate and 0.5 parts of a swelling promoter. Ultrasonic cleaning was performed at 32.0 ± 0.5°C, with an ultrasonic frequency of 40 kHz and an amplitude set to 1.2 times the fiber diameter, for 12 minutes.

[0065] S2, gradient staining:

[0066] The pretreated fiber enters the dyeing tank at a linear speed of 0.8m / s and the dye solution is injected simultaneously; the temperature of the dyeing tank is controlled in sections:

[0067] 40-50℃ stage: heating rate 0.8℃ per minute;

[0068] 50-60℃ stage: heating rate 1.5℃ per minute;

[0069] 60-65℃ stage: heating rate 0.5℃ per minute;

[0070] The dye liquor and the fiber flow in opposite directions, with a velocity difference of 0.8 m / s;

[0071] S3, color fixation and strengthening:

[0072] A quaternary ammonium salt-type color fixing agent was injected into the product obtained in S2, while adjusting the vortex speed, and then the product was treated at 50°C for 20 minutes;

[0073] S4, Spinning and Forming:

[0074] The fixed color fiber is introduced into the spinning machine with a drafting force of 0.6-0.9N / tex, a spindle speed of 9000-12000rpm, and a winding ratio of 1:4.2.

[0075] The weight proportions of the raw materials used in the above-mentioned gradient color velvet spinning process are as follows:

[0076] Cationic Red X-GRL: 8 parts,

[0077] Cationic blue YB: 7 parts,

[0078] Rare earth mordant LaCl3: 0.8 parts,

[0079] Citric acid-sodium citrate buffer: 2 parts,

[0080] Fiber swelling promoter: 1.8 parts,

[0081] Deionized water: 1000 parts.

[0082] Example 2

[0083] This embodiment provides a gradient color velvet spinning process, comprising the following steps:

[0084] S1. Fiber pretreatment:

[0085] The velvet fibers were immersed in a pretreatment solution containing 3.85 wt% sodium citrate and 0.5 parts of a swelling promoter. Ultrasonic cleaning was performed at 32.0 ± 0.5°C, with an ultrasonic frequency of 40 kHz and an amplitude set to 1.35 times the fiber diameter for 12 minutes.

[0086] S2, gradient staining:

[0087] The pretreated fiber enters the dyeing tank at a linear speed of 0.8m / s and the dye solution is injected simultaneously; the temperature of the dyeing tank is controlled in sections:

[0088] 40-50℃ stage: heating rate 0.8℃ per minute;

[0089] 50-60℃ stage: heating rate 1.5℃ per minute;

[0090] 60-65℃ stage: heating rate 0.5℃ per minute;

[0091] The dye liquor and the fiber flow in opposite directions, with a velocity difference of 1.05 m / s;

[0092] S3, color fixation and strengthening:

[0093] A quaternary ammonium salt-type color fixing agent was injected into the product obtained in S2, and the product was treated at 50°C for 20 minutes;

[0094] S4, Spinning and Forming:

[0095] The fixed-color fiber was introduced into the spinning machine with a drafting force of 0.75 N / tex, a spindle speed of 10500 rpm, and a winding ratio of 1:4.2;

[0096] The weight proportions of the raw materials used in the above-mentioned gradient color velvet spinning process are as follows:

[0097] Cationic Red X-GRL: 10 parts,

[0098] Cationic blue YB: 8.3 parts,

[0099] Rare earth mordant LaCl3: 1.15 parts,

[0100] Citric acid-sodium citrate buffer: 2.5 parts,

[0101] Fiber swelling promoter: 1.8 parts,

[0102] Deionized water: 1000 parts.

[0103] Example 3

[0104] This embodiment provides a gradient color velvet spinning process, comprising the following steps:

[0105] S1. Fiber pretreatment:

[0106] The velvet fibers were immersed in a pretreatment solution containing 4.2 wt% sodium citrate and 0.5 parts of a swelling promoter. Ultrasonic cleaning was performed at 32.0 ± 0.5°C, with an ultrasonic frequency of 40 kHz and an amplitude set to 1.5 times the fiber diameter for 12 minutes.

[0107] S2, gradient staining:

[0108] The pretreated fiber enters the dyeing tank at a linear speed of 0.8m / s and the dye solution is injected simultaneously; the temperature of the dyeing tank is controlled in sections:

[0109] 40-50℃ stage: heating rate 0.8℃ per minute;

[0110] 50-60℃ stage: heating rate 1.5℃ per minute;

[0111] 60-65℃ stage: heating rate 0.5℃ per minute;

[0112] The dye liquor and the fiber flow in opposite directions, with a velocity difference of 1.3 meters per second;

[0113] S3, color fixation and strengthening:

[0114] A quaternary ammonium salt-type color fixing agent was injected into the product obtained in S2, and the product was treated at 50°C for 20 minutes;

[0115] S4, Spinning and Forming:

[0116] The fixed-color fiber was introduced into the spinning machine with a drafting force of 0.9 N / tex, a spindle speed of 12000 rpm, and a winding ratio of 1:4.2;

[0117] The weight proportions of the raw materials used in the above-mentioned gradient color velvet spinning process are as follows:

[0118] Cationic Red X-GRL: 12 parts,

[0119] Cationic blue YB: 10 parts,

[0120] Rare earth mordant LaCl3: 1.5 parts,

[0121] Citric acid-sodium citrate buffer: 3 parts,

[0122] Fiber swelling promoter: 1.8 parts,

[0123] Deionized water: 1000 parts.

[0124] Comparative Example 1

[0125] This comparative example provides a velvet spinning process, comprising the following steps:

[0126] S1, fiber pretreatment: sodium citrate concentration was changed to 3.0wt%, amplitude was adjusted to 1.2 times, and the rest of the contents remained unchanged;

[0127] The remaining steps are consistent with those in Example 1.

[0128] The weight proportions of the raw materials used in the above velvet spinning process are as follows:

[0129] The raw material ratio is consistent with that in Example 1.

[0130] Comparative Example 2

[0131] This comparative example provides a gradient color velvet spinning process, comprising the following steps:

[0132] S1. Fiber pretreatment: The amplitude is adjusted to 1.8 times the fiber diameter, and the rest of the content is consistent with Example 1;

[0133] The remaining steps are consistent with those in Example 1.

[0134] The weight proportions of the raw materials used in the above velvet spinning process are as follows:

[0135] The raw material ratio is consistent with that in Example 2.

[0136] Comparative Example 3

[0137] This comparative example provides a gradient color velvet spinning process, comprising the following steps:

[0138] S2, gradient dyeing: the flow rate difference is adjusted to 0.4 m / s, and the rest of the content is consistent with Example 1;

[0139] The remaining steps are consistent with those in Example 1.

[0140] The weight proportions of the raw materials used in the above velvet spinning process are as follows:

[0141] The raw material ratio is consistent with that in Example 1.

[0142] Comparative Example 4

[0143] This comparative example provides a gradient color velvet spinning process, comprising the following steps:

[0144] S4, spinning and forming: the drafting force is adjusted to 1.3 N / tex, the spindle speed is changed to 12000 rpm, and the rest of the content is consistent with Example 3.

[0145] The weight proportions of the raw materials used in the above velvet spinning process are as follows:

[0146] The raw material ratio is consistent with that in Example 3.

[0147] Comparative Example 5

[0148] This comparative example provides a gradient color velvet spinning process, comprising the following steps: consistent with Example 1.

[0149] The weight proportions of the raw materials used in the above velvet spinning process are as follows:

[0150] Cationic Red X-GRL: 5 parts,

[0151] Cationic blue YB: 4 parts,

[0152] The remaining raw materials are the same as in Example 1.

[0153] Comparative Example 6

[0154] This comparative example provides a gradient color velvet spinning process, comprising the following steps: consistent with Example 3.

[0155] Rare earth mordant LaCl3: 2.2 parts,

[0156] The remaining raw materials are the same as in Example 3.

[0157] Performance testing

[0158] Detection method:

[0159] Dye utilization test

[0160] Test standard: ISO105-X16:2016;

[0161] Testing equipment: high performance liquid chromatography;

[0162] Sample treatment: Take 50 mL of the dyeing waste liquid and filter it using a 0.45 μm filter membrane. Then, the filtrate is detected using a high performance liquid chromatography (HPLC).

[0163] Calculation formula:

[0164]

[0165] Among them, C 废 is the waste liquid dye concentration; C 原 is the initial dye solution concentration.

[0166] Color gradient transition volatility

[0167] Test standard: FZ / T01101-2017;

[0168] Sample preparation:

[0169] First, fix the yarn sample on a black background plate; then divide the gradient section into equidistant test points with a spacing of 6 mm;

[0170] Testing equipment: ultra-depth-of-field three-dimensional microscope, spectrophotometer;

[0171] Test process: Measure the CIELAB chromaticity value point by point along the yarn axis;

[0172] Calculation formula:

[0173]

[0174] Where L is the length of the gradient area, and dE / dl is the rate of change of color difference per unit length.

[0175] Color fastness test

[0176] Test standard: GB / T3921-2008;

[0177] Sample preparation: Cut a sample of size 4 × 10 cm and sew it to the SDC multi-fiber adjacent fabric, while keeping the spacing 1 cm;

[0178] Testing process:

[0179] Place the fabric of the sewn sample in a washing solution containing 5g / LIEC standard detergent and 10 6mm diameter steel balls, then oscillate at a rate of 40r / min in a constant temperature water bath at 40℃±2℃ for 30 minutes. After rinsing with clean water three times, hang it in an environment of 25℃±5℃ to dry, with each rinse taking 2 minutes. Finally, evaluate the color fastness grade by comparing with the standard gray sample card.

[0180] Performance comparison table:

[0181]

[0182] Conclusion of the embodiment:

[0183] Combining Examples 1-3 and Comparative Example 1 with the performance comparison table, it can be seen that when the sodium citrate concentration of the pretreatment solution is reduced to 3.0wt%, insufficient fiber swelling leads to obstruction of dye penetration, the dye utilization rate drops from the average value of 95.1% in the examples to 52.1%, the color gradient transition fluctuation rate increases from 5.6% to 31.2%, and the color fastness to washing deteriorates from level 5 to level 3, proving that sodium citrate ≥3.5wt% is the key threshold for maintaining fiber micropore expansion;

[0184] Combining Examples 1-3 and Comparative Example 2 with the performance comparison table, it can be seen that increasing the ultrasonic amplitude to 1.8 times the fiber diameter causes fiber structure damage, the dye utilization rate decreases by 20.3% compared with the average value of the examples, the transition fluctuation rate increases to 17.5%, and the rubbing color fastness decreases to level 3-4, confirming that an amplitude greater than 1.5 times will damage the fiber integrity;

[0185] Combining Examples 1-3 and Comparative Example 3 with the performance comparison table, it can be seen that when the dye liquor and the fiber flow in the same direction and the velocity difference is only 0.4 m / s, the probability of dye collision is reduced, causing the utilization rate to drop to 67.0%, and the transition fluctuation rate deteriorates to 24.7%, confirming that a reverse flow velocity difference of ≥0.8 m / s can ensure dynamic penetration of the dye liquor;

[0186] Combining Examples 1-3 and Comparative Example 4 with the performance comparison table, it can be seen that increasing the draft force to 1.3 N / tex causes the yarn structure to be destroyed, the hairiness index rises to 5.8, and the color fastness to washing drops to level 4, confirming that the draft force of 0.6 to 0.9 N / tex can balance fiber orientation and damage;

[0187] Combining Examples 1-3 and Comparative Example 5 and the performance comparison table, it can be seen that an imbalance in the red-blue dye ratio causes hue loss of control, with a transition fluctuation rate as high as 42.3% and a dye utilization rate of only 32.3%, confirming that a red-blue ratio of 1.2±0.1 can control a gradient color spectrum;

[0188] Combining Examples 1-3 and Comparative Example 6 and the performance comparison table, it can be seen that excessive LaCl3 induces fiber hydrolysis, the color fastness to washing and the color fastness to rubbing are both reduced to level 2, and the transition volatility increases to 27.6%, proving that limiting the amount of mordant to 0.8 to 1.5 parts can maintain the stability of the complex bond.

[0189] This specific embodiment is only an explanation of the present application, and it is not a limitation of the present application. Those skilled in the art can make their own interpretations of the present embodiment as needed after reading this specification.

[0190] Modifications that do not contribute to creativity but are subject to patent application as long as they fall within the scope of the claims of this application

[0191] Protection of the law.

Claims

1. Gradient color velvet spinning process, characterized in that: The following steps are involved: S1. Fiber pretreatment: immerse the velvet fiber in a pretreatment solution containing 3.5-4.2 wt% sodium citrate, and ultrasonically clean it at 32±0.5°C for 12 min, with an ultrasonic frequency of 40 kHz and an amplitude controlled at 1.2-1.5 times the fiber diameter; S2. Gradient dyeing: Place the pretreated fiber in a dyeing tank, increase the temperature to 65°C at a gradient of 1.2°C / min, and simultaneously inject a dye solution composed of the following parts by weight: Cationic dye 15-22 parts, Rare earth mordant LaCl 3: 0.8~1.5 parts, 2-3 parts of pH buffer, 1000 parts of deionized water, Among them, the dye liquor flow rate is controlled in the opposite direction to the fiber movement direction, and the flow rate difference is 0.8-1.3 m / s; S3. Color fixation and strengthening: After draining the dye liquor, inject the color fixing agent and treat in a 50℃ eddy current field for 20 minutes. The eddy current intensity and fiber linear density satisfy the relationship: Ψ=0.07ρ+3.2, where Ψ is the eddy current speed / rpm and ρ is the fiber linear density / dtex; S4. Spinning: The fixed color fiber is introduced into the spinning machine with a drafting force of 0.6-0.9N / tex, a spindle speed of 9000-12000rpm, and a winding ratio of 1:4.

2.

2. The gradient color velvet spinning process according to claim 1, characterized in that: In the step S1, 0.5 parts of fiber swelling promoter is added to the pretreatment liquid, and its structural formula is C 12 H 25 O-(CH2CH2O)3-SO3Na.

3. The gradient color velvet spinning process according to claim 1, characterized in that: The S2 gradient heating is divided into three sections: 40-50℃ stage: heating rate 0.8℃ / min, 50-60℃ stage: heating rate 1.5℃ / min, 60-65℃ stage: heating rate 0.5℃ / min.

4. The gradient color velvet spinning process according to claim 1, characterized in that: In step S2, the pH value of the dye solution is controlled at 4.5±0.2 by using a citric acid-sodium citrate buffer system.

5. The gradient color velvet spinning process according to claim 1, characterized in that: The color fixing agent in step S3 is a quaternary ammonium salt cationic polymer with a molecular weight distribution PDI of ≤1.

3.

6. The gradient color velvet spinning process according to claim 1, characterized in that: In the step S4, atomized lubricant is applied to the fiber before spinning, wherein the atomized particle size is controlled at 10-15 μm and the applied amount is 0.2 g / tex.

7. The gradient color velvet spinning process according to claim 1, characterized in that: In step S2, 0.05 parts of a defoamer is added to the dye solution, which is a polydimethylsiloxane-silicon dioxide composite.

8. Gradient color velvet, characterized by: The gradient color velvet spinning process according to claims 1 to 7 comprises the following components in parts by weight: Cationic Red X-GRL: 8-12 parts, Cationic blue YB: 7-10 parts, Rare earth mordant LaCl3: 0.8-1.5 parts, Citric acid-sodium citrate buffer: 2-3 parts, Fiber swelling promoter: 1.8 parts, Deionized water: 1000 parts; The component content must meet the following requirements: cationic red X-GRL / cationic blue YB=1.2±0.

1.

9. The gradient color velvet according to claim 8, characterized in that: The fiber swelling promoter comprises 80 wt % of alkyl polyoxyethylene ether sulfate and 20 wt % of cocamidopropyl betaine.

10. The gradient color velvet according to claim 8, characterized in that: The color fastness of the gradient color velvet is ≥ level 5.

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