Gauze printing imitation sand washing process

Abstract

The invention relates to the technical field of textile printing and after-finishing, and discloses a gauze printing imitation sand washing process which comprises the following steps: performing chemical activation pretreatment on a gauze base material to provide a suitable surface for subsequent treatment; the split type printing paste with the interpenetrating network characteristic and the dual response function is prepared, and the binding force with a base material is enhanced; a pressure grading response type superposition overprinting process is adopted, and preliminary construction of patterns is achieved; an interpenetrating polymer network is constructed through a thermally induced chain reaction, and a printing structure is stabilized; and performing purification treatment and shaping finishing on the gauze to obtain a finished product. Chemical activation pretreatment is carried out on a gauze base material, functional printing paste containing dual-response microcapsules is cooperatively adopted, pressure and heat energy are used for carrying out grading and response type printing and curing on the paste, and in the single technological process, a finished product is endowed with excellent durability and fastness, soft hand feeling and controllable sand washing imitating appearance.

Description

Technical Field

[0001] The invention relates to the technical field of textile printing and post-finishing, in particular to a gauze printing imitation sand washing process. Background Art

[0002] Textiles with a sand-washed look are popular in the clothing and home textile markets for their unique sense of age and retro appearance. Traditional techniques to achieve this visual effect usually rely on physical wear or chemical treatment of durable fabrics such as denim. Physical wear methods mainly use hard particles such as pumice and corundum to strongly rub the fabric surface; chemical treatment methods use strong oxidants such as potassium permanganate or biological agents such as cellulase to etch the fibers, thereby creating irregular fading and wear marks on the fabric surface.

[0003] However, the physical wear process will produce a large amount of wastewater containing stone powder and short fibers, causing environmental pollution. At the same time, the intense mechanical action significantly reduces the mechanical strength of the fabric. The chemical treatment process also consumes a lot of water resources and produces chemical wastewater, and the use of chemical reagents also damages the fabric fibers. These defects make the traditional imitation sand washing process difficult to apply to medical gauze, clothing gauze and other thin fabrics with loose structure and low inherent strength. Forcible application will cause the fabric to be damaged and cannot meet the use requirements.

[0004] To solve the above problems, technical personnel in the industry have tried to use paint printing to simulate the sandwashing effect on the surface of thin fabrics such as gauze. However, the existing paint printing sandwashing technology still has a series of unresolved problems. First, the film layer formed by ordinary adhesives after curing is stiff, which seriously affects the original soft feel of the gauze; second, the printing layer and the fiber substrate are only bonded by physical coating, and the bonding force is weak, resulting in poor washing and friction resistance of the finished product. The printed pattern is prone to cracking, delamination, and even falling off after repeated use. In addition, the existing printing, aging, and soft finishing processes are independent of each other, the process flow is long, and the production efficiency is low, which makes it difficult to meet the needs of modern industrial production. Summary of the Invention

[0005] The invention aims to provide a gauze printing imitation sand washing process, which solves the problems in the existing paint printing imitation sand washing technology, such as stiff feel of finished products, poor durability and fastness, and complicated and inefficient production process caused by adhesive selection, interface bonding mode and process design.

[0006] To achieve the above objectives, the present invention is implemented through the following technical solutions: A gauze printing imitation sand washing process comprises the following steps: S1. Activate and pre-treat the gauze substrate to provide a suitable surface for subsequent treatment; S2. Based on the activated pretreated gauze substrate, a split printing paste with interpenetrating network characteristics and dual response function is prepared to enable the paste to better bond with the substrate; S3, applying the prepared split printing paste to the activated pre-treated gauze substrate in a pressure-graded responsive overprinting manner to achieve preliminary construction of the pattern; S4. performing a thermal chain reaction and interpenetrating polymer network construction on the gauze substrate that has completed the pressure-graded responsive overprinting to form a stable printing structure; S5. Purify and shape the gauze constructed through the thermal chain reaction and interpenetrating polymer network to obtain a finished product that meets the requirements. Preferably, the step S1 includes: Dipping cotton gauze into an aqueous solution of an amino-modified organosilane coupling agent with a concentration of 10-50 g / L; The impregnated gauze is dried at 100-120°C for 2-3 minutes to allow the silane coupling agent to react with the hydroxyl groups on the fiber surface to form active amino groups.

[0007] Preferably, the split printing paste in step S2 includes: Base slurry: water-based acrylic emulsion containing epoxy groups, added in an amount of 20-40 parts by weight; Special particle slurry: containing 10-20 parts by weight of closed polyurethane prepolymer, 5-15 parts by weight of pressure-sensitive microcapsules, and 5-15 parts by weight of heat-sensitive microcapsules; The wall material of the pressure-sensitive microcapsule is melamine-formaldehyde resin, and the capsule core is hydroxyl-terminated polydimethylsiloxane; The wall material of the thermosensitive microcapsule is methyl methacrylate-acrylonitrile copolymer, and the capsule core contains isododecane, hydroxyethyl cellulose, sodium bicarbonate and polyol active substances.

[0008] Preferably, the weight ratio of isododecane, hydroxyethyl cellulose, sodium bicarbonate and polyol active ingredient in the capsule core of the thermosensitive microcapsule is 50-70:5-15:1-5:2-8.

[0009] Preferably, the scraper pressure of the pressure graded responsive overprinting in step S3 is 5-10 kg / cm 2 , and the rupture pressure threshold of the pressure-sensitive microcapsule is 4-8kg / cm 2 , the rupture temperature threshold of thermosensitive microcapsules is 120-140℃.

[0010] Preferably, the superimposition printing is completed in two steps: The first overprinting uses a 100-150 mesh screen to print the base slurry, and the slurry penetration depth is 30-50% of the fiber diameter; The second overprinting uses a 60-100 mesh screen to print a special particle slurry, and the slurry penetration depth covers 80-120% of the base slurry layer.

[0011] Preferably, step S4 includes: The overprinted gauze is passed through a hot air zone at 135-145°C for 40-70 seconds to deblock the blocked polyurethane prepolymer and release the active -NCO groups; The treated gauze was irradiated with a near-infrared radiation device in the 800-950nm band, with a radiation energy density of 15-35kW / m 2 , lasting 5-15 seconds, triggering the rupture of the thermosensitive microcapsule wall material; The polyol active substance released from the core of the thermosensitive microcapsule undergoes cross-linking reaction with the -NCO group of the polyurethane prepolymer, the acrylate epoxy group and the amino group on the fiber surface to form a three-dimensional interpenetrating network structure.

[0012] Preferably, in the cross-linking reaction, the molar ratio of -NCO group to epoxy group, amino group and polyol is 1:0.3-0.5:0.2-0.4:0.1-0.3.

[0013] Preferably, step S5 includes: The heat-treated gauze is soaped in warm water at 40-60°C for 1-2 minutes, then dipped in amino silicone oil softener, and dried at 110-130°C for setting.

[0014] Preferably, the padding concentration of the amino silicone oil softener is 20-50 g / L, the padding rate is 70-90%, and the cloth passes through the oven at a speed of 2-5 m / min during drying and shaping.

[0015] In summary, the present invention includes at least one of the following beneficial technical effects: 1. The present invention uses aminosilane to activate and pretreat gauze fibers, constructing chemically bonded "anchor points" on the fiber surface, and combining this with a three-dimensional interpenetrating polymer network constructed by subsequent thermal reaction to firmly bond the printing paste to the fibers through chemical bonds and physical entanglement. This helps to solve the problems of traditional pigment-printed imitation sand-washing products, such as stiff feel, poor washing and abrasion resistance, and easy shedding and delamination of the printed layer.

[0016] 2. This invention utilizes a specially designed dual-responsive microcapsule system. By precisely controlling printing pressure and subsequent radiation energy, it triggers the in-situ softening function of the pressure-sensitive microcapsules and the internal distressing effect generation of the heat-sensitive microcapsules. This graded response mechanism integrates the traditionally separate softening, printing, and distressing steps into an integrated chemical reaction process, shortening the production cycle while enabling the depth and texture of the distressing effect to be precisely controlled through process parameters.

[0017] 3. The present invention uses the internal chemical reaction of thermosensitive microcapsules after being heated to simulate the wear effect of physical sand washing, which helps to replace the physical grinding process that relies on large amounts of water, pumice and chemical additives in traditional processes. It eliminates the generation of stone powder-containing wastewater from the source, significantly reduces energy consumption such as water and electricity, and avoids the strength damage to the gauze substrate caused by mechanical grinding, making the final product performance better. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is a process flow chart of the present invention. DETAILED DESCRIPTION

[0019] Combined with attachment Figure 1 , further details of this application are given.

[0020] Example 1: Gauze printing imitation sand washing process (medium effect) S1. Activation pretreatment of gauze substrate: Select pure cotton gauze and put it into a padding machine to pad with an aqueous solution of an amino-modified organic silane coupling agent with a concentration of 30 g / L.

[0021] After padding, the gauze was placed in an oven at 110°C for drying for 2.5 minutes. This step was intended to allow the silane coupling agent to react with the hydroxyl groups of cellulose and graft active amino groups.

[0022] S2. Preparation of split printing paste: Basic paste: 300 g of epoxy-containing water-based acrylic emulsion, 10 g of thickener and water are mixed and stirred evenly.

[0023] Special particle slurry: Mix 150g of closed polyurethane prepolymer, 100g of pressure-sensitive microcapsules and 100g of heat-sensitive microcapsules.

[0024] The rupture pressure threshold of the pressure-sensitive microcapsule is 6 kg / cm 2 ; The rupture temperature threshold of the thermosensitive microcapsule is 130℃.

[0025] The weight ratio of the core components of the thermosensitive microcapsule is isododecane:hydroxyethyl cellulose:sodium bicarbonate:polyol active substance=60:10:3:5.

[0026] S3, pressure-graded responsive overlay printing First overprint: Use 120 mesh screen, 7.5kg / cm 2 The base slurry is printed with a blade pressure of 100%.

[0027] Second overprint: After 5 minutes, replace it with an 80-mesh screen and print the special particle slurry with the same pressure.

[0028] S4. Thermally induced chain reaction and interpenetrating polymer network construction Hot air treatment: The gauze was passed through a hot air oven at 140°C for 55 seconds.

[0029] Near infrared radiation: 25kW / m 2 The radiation energy density and near-infrared light in the 850nm band were irradiated for 10 seconds.

[0030] S5. Purification and shaping of finished products: Soap the gauze in 50°C warm water for 1.5 minutes to remove floating color and unreacted matter.

[0031] After soaping, the surface was padded with 35 g / L amino silicone oil softener, and the plucking rate was controlled to be 80%.

[0032] Finally, the gauze is dried and shaped at 120°C at a speed of 3.5m / min. The finished product has a soft hand feel, a clear distressed texture, and good color fastness.

[0033] Example 2: Gauze printing imitation sand washing process (slight effect) S1. Activation pretreatment of gauze substrate: Take pure cotton gauze, dip it into an aqueous solution of an amino-modified organic silane coupling agent with a concentration of 10 g / L, and then dry it at 100° C. for 2 minutes for later use.

[0034] S2. Preparation of split printing paste Base slurry: Contains 200g of water-based acrylic emulsion containing epoxy groups.

[0035] Special particle slurry: contains 100g closed polyurethane prepolymer, 50g pressure-sensitive microcapsules and 50g heat-sensitive microcapsules.

[0036] The rupture pressure threshold of the pressure-sensitive microcapsule is 4kg / cm 2 ; The rupture temperature threshold of the thermosensitive microcapsule is 120℃.

[0037] The weight ratio of the core components of the thermosensitive microcapsule is isododecane:hydroxyethyl cellulose:sodium bicarbonate:polyol active matter=50:5:1:2.

[0038] S3, pressure-graded responsive overlay printing First overprint: Use 100 mesh screen, 5kg / cm 2 The base slurry is printed with a blade pressure of 100%.

[0039] Second overprint: Change to 60 mesh screen, 5kg / cm 2 Special particle slurry is printed with superimposed blade pressure.

[0040] S4. Thermally induced chain reaction and interpenetrating polymer network construction Hot air treatment: The gauze was passed through a hot air zone at 135°C for 40 seconds.

[0041] Near infrared radiation: 15kW / m 2 The radiation energy density and near-infrared light in the 800nm ​​band were irradiated for 5 seconds.

[0042] S5. Finished product purification and shaping and finishing: The gauze is soaped in 40°C warm water for 1 minute, and then dipped in 20g / L amino silicone oil softener, with the liquid rate controlled to 70%.

[0043] Finally, the fabric is dried and shaped in a stentering machine at 110°C at a speed of 2m / min. The finished product has a delicate old-fashioned texture and the fabric strength is well maintained.

[0044] Example 3 Gauze printing imitation sand washing process (heavy effect) S1. Pretreatment of Gauze Base Material Activation: Take pure cotton gauze and dip it into a 50 g / L aqueous solution of an amino-modified organosilane coupling agent. After dipping, dry it at 120° C. for 3 minutes before use.

[0045] S2. Preparation of split printing paste Base slurry: Contains 400g of water-based acrylic emulsion containing epoxy groups.

[0046] Special particle slurry: contains 200g closed polyurethane prepolymer, 150g pressure-sensitive microcapsules and 150g heat-sensitive microcapsules.

[0047] The rupture pressure threshold of the pressure-sensitive microcapsule is 8kg / cm 2 ; The rupture temperature threshold of the thermosensitive microcapsule is 140℃.

[0048] The weight ratio of the core components of the thermosensitive microcapsule is isododecane:hydroxyethyl cellulose:sodium bicarbonate:polyol active matter=70:15:5:8.

[0049] S3, pressure-graded responsive overlay printing First overprint: Use 150 mesh screen, 10kg / cm 2 The base slurry is printed with a blade pressure of 100%.

[0050] Second overprint: Change to 100 mesh screen, 10kg / cm 2 Special particle slurry is printed with superimposed blade pressure.

[0051] S4. Thermally induced chain reaction and interpenetrating polymer network construction Hot air treatment: The gauze was passed through a hot air zone at 145°C for 70 seconds.

[0052] Near infrared radiation: 35kW / m 2 The radiation energy density and near-infrared light in the 950nm band were irradiated for 15 seconds.

[0053] S5. Finished product purification and shaping and finishing: The gauze is soaped in 60°C warm water for 2 minutes, and then padded with 50g / L amino silicone oil softener, with the plucking rate controlled at 90%.

[0054] Finally, the fabric is dried and shaped in a stentering machine at 130°C at a speed of 5m / min. The finished product has a distinct antique style, rich hand feel and excellent wear resistance.

[0055] Comparative Example 1: Compared with Example 1, the difference is that the activation pretreatment of the gauze substrate in step S1 is omitted, and untreated ordinary cotton gauze is directly used for subsequent printing. The other steps and parameters are the same.

[0056] Comparative Example 2: Compared with Example 1, the difference is that in the slurry preparation of step S2, 300g of epoxy-containing aqueous acrylate emulsion and 150g of blocked polyurethane prepolymer that form the interpenetrating network are replaced by 450g of commercially available conventional self-cross-linking acrylate adhesive, and the remaining steps and parameters are the same.

[0057] Comparative Example 3: Compared with Example 1, the difference is that: in step S2, a split slurry is not prepared, but the base slurry and all components of the special particle slurry (acrylate emulsion, polyurethane prepolymer, two microcapsules, etc.) are directly mixed to form a single printing slurry, and an 80-mesh screen is used for printing once in step S3. The remaining steps and parameters are the same.

[0058] Comparative Example 4: Compared with Example 1, the difference is that in the preparation of the special particle slurry in step S2, the addition of 100g of pressure-sensitive microcapsules is omitted, and the remaining steps and parameters are the same.

[0059] Comparative Example 5: Compared with Example 1, the difference is that in the preparation of the special particle slurry in step S2, the addition of 100g of thermosensitive microcapsules is omitted, and the remaining steps and parameters are the same.

[0060] Comparative Example 6: Compared with Example 1, the difference is that the core component of the thermosensitive microcapsule used in step S2 does not contain sodium bicarbonate and polyol active ingredients, and is composed only of isododecane and hydroxyethyl cellulose. The remaining steps and parameters are the same.

[0061] Comparative Example 7: Compared with Example 1, the difference is that in step S3, the scraper pressure is reduced from 7.5 kg / cm 2 Reduced to 3kg / cm 2 (lower than the rupture pressure threshold of the pressure-sensitive microcapsule), and the remaining steps and parameters are the same.

[0062] Comparative Example 8: Compared with Example 1, the difference is that in step S4, the near-infrared radiation treatment step is cancelled, and the hot air treatment time is extended from 55 seconds to 85 seconds (that is, the total heating time is basically the same), and the remaining steps and parameters are the same.

[0063] Test Example 1: Quantitative evaluation of substrate activation pretreatment on wet friction resistance of printing Experimental materials and samples Example 1 Sample: The finished product of the imitation sand-washed gauze prepared according to the steps of the aforementioned "Example 1" (including the substrate activation pretreatment).

[0064] Comparative Example 1 sample: a finished product of imitation sand-washed gauze prepared according to the steps of the aforementioned "Comparative Example 1" (excluding substrate activation pretreatment).

[0065] Experimental equipment and consumables: Y571 type friction color fastness tester, spectrophotometer (or equipment with equivalent performance), standard friction cotton cloth, distilled water.

[0066] Experimental procedures Wet rubbing color fastness test sample preparation: from the finished fabric samples of "Example 1 sample" and "Comparative Example 1 sample", cut 5 samples each with a size of not less than 140 mm × 50 mm.

[0067] Preparation of the small white friction cloth: Take a standard friction cotton cloth and moisten it with distilled water to ensure that its moisture content reaches between 95% and 105% of its dry weight.

[0068] Friction operation: Fix the sample to the base of the friction meter, fix the moistened white friction cloth to the friction head, apply 9±0.2N vertical pressure, and rub back and forth 10 times at a frequency of 60±1 times per minute.

[0069] Quantitative evaluation of staining and data recording Drying: After each friction, carefully remove the stained white friction cloth and let it dry naturally at room temperature.

[0070] Instrument measurement: Use a spectrophotometer to measure the chromaticity value of the center point of the stained area of ​​5 pieces of dried stained white cloth, taking a piece of unrubbed standard rubbed white cloth from the same batch as the reference sample.

[0071] Data recording: The instrument automatically calculates and records the total color difference of each stained white cloth relative to the reference sample, and calculates the average value of 5 tests.

[0072] Color Difference Calculation and Definition The evaluation index of this test is the wet friction color difference ΔE ★s, defined as the total color difference between the stained white cloth and the reference sample, is calculated according to the following formula. The smaller the value, the lower the degree of staining and the better the color fastness to wet rubbing: Where ΔE ＊ s is wet friction staining, ΔL * The stained cloth and the reference cloth are * Difference on axis (brightness), Δa * The stained cloth and the reference cloth are * The difference between (red / green), Δb * The stained cloth and the reference cloth are in b * Difference on the axis (yellow / blue); Test data Table 1: Effects of different pretreatment methods on the color fastness to wet rubbing of finished products Sample Group <![CDATA[Wet rubbing color staining ΔE ★ s (average value)]]> Example 1 Sample 1.85 Comparative Example 1 Sample 7.52 Experimental Summary The test data clearly show that the wet friction color fastness of the sample of Example 1 using the substrate activation pretreatment process of the present invention is significantly better than that of the sample of Comparative Example 1 which has not been pretreated. Specifically, the total color difference value of the stained white cloth after rubbing with the sample of Example 1 is extremely low, proving that only a very small amount of pigment is transferred from the printing layer, showing excellent durability.

[0073] This performance improvement is due to the introduction of a key chemical anchoring step before printing in the present invention. By pretreating the gauze substrate with an amino-modified organosilane coupling agent, highly active amino functional groups can be grafted onto the cellulose macromolecules of the cotton fiber, thereby transforming the originally chemically relatively inert fiber surface into an active interface full of chemical reaction sites.

[0074] In comparison, the sample in Comparative Example 1 relies solely on the physical film-forming effect of the adhesive in the printing slurry. The adhesive and the fiber are bonded only by weak van der Waals forces, which are further weakened after swelling in water. Therefore, the printed layer is very easy to fall off during wet friction, resulting in a large amount of pigment being transferred to the friction cloth, thereby producing a huge color difference. The process of the present invention, through the strategy of "chemical anchoring first, then in-situ networking", upgrades traditional physical adhesion to molecular-level chemical bonding, fundamentally solving the problem of interfacial bonding between the paint printing layer and the substrate, and ensuring the excellent fastness of the product under harsh conditions.

[0075] Test Example 2: Quantitative evaluation of the softness and washability of finished products using the IPN system and conventional adhesives Experimental materials and samples Example 1 Sample: A finished product of imitation sand-washing gauze prepared according to the steps of the aforementioned "Example 1" (using a composite system of epoxy-containing water-based acrylate and blocked polyurethane prepolymer).

[0076] Comparative Example 2 Sample: A finished product of imitation sand-washing gauze prepared according to the steps of the aforementioned "Comparative Example 2" (using conventional self-crosslinking acrylic adhesive).

[0077] Experimental equipment and consumables: YG002B fabric stiffness tester, standard drum washing machine, spectrophotometer (or equipment with equivalent performance), standard neutral detergent.

[0078] Experimental procedures Fabric softness test (flexural stiffness test) Sample preparation: From the printed areas of the finished fabric samples of "Example 1 Sample" and "Comparative Example 2 Sample", five rectangular samples with a size of 25 mm × 200 mm were cut along the warp and weft directions respectively. Before testing, the samples were conditioned under standard atmospheric conditions (temperature 20 ± 2°C, relative humidity 65 ± 4%) for at least 24 hours.

[0079] Instrument operation: Place the sample flat on the horizontal platform of the stiffness tester, align one end of the sample with the edge of the platform, press the other end of the sample with a pressure block, and then push the platform at a constant speed so that the sample bends along a 41.5-degree slope due to its own weight. When the front end of the sample touches the slope, stop pushing immediately and read the extended length of the sample from the platform scale, which is the bending length (unit: mm). Both the front and back sides of each sample need to be tested.

[0080] Data processing: Calculate the average value of the warp and weft bending lengths of each group of samples respectively, and then calculate the total average bending length. This value is used as an evaluation index. The smaller the value, the lower the rigidity of the fabric, that is, the softer it is.

[0081] Washing resistance test This test is designed to quantify the color change of a sample after multiple wash cycles.

[0082] Pre-test measurement: Using a spectrophotometer, select 5 different locations within the printed area of ​​each sample to be tested (approximately 30 cm × 30 cm in size), measure their initial chromaticity values, and calculate the average value as the pre-washing reference.

[0083] Washing procedure: Place the sample in a household drum washing machine, add standard neutral detergent, set the standard washing procedure for cotton fabrics (water temperature 40°C, speed 800 rpm), and wash continuously for 20 times.

[0084] Measurement after testing: Dry the washed sample and adjust the humidity according to standard atmospheric conditions. Measure its chromaticity value again at the same five locations as before washing and calculate the average value.

[0085] Color Difference Calculation and Definition The evaluation index of this test is the color difference of washing resistance It is defined as the total color difference of the sample before and after washing, calculated according to the following formula. This value is an evaluation index. The smaller the value, the smaller the color change and the better the washability: in, is the total color difference before and after washing, ΔL *1 The samples before and after washing are in L *1 Difference on axis (brightness), Δa *1 The samples before and after washing are *1 Difference on the axis (red / green), Δb *1 The samples before and after washing are in b *1 Difference on the axis (yellow / blue); test data Table 2: Effects of IPN system and conventional adhesives on physical properties of finished products Experimental Summary The test data clearly shows that the sample of Example 1 using the IPN system of the present invention is significantly superior to the sample of Comparative Example 2 using a conventional adhesive in terms of two key physical indicators: softness and wash resistance. Specifically, the total average bending length value of the sample of Example 1 is smaller, demonstrating its better physical softness. At the same time, its total color difference value after 20 standard washing cycles is also significantly smaller, demonstrating its higher color stability and better wash fastness.

[0086] This performance advantage stems from the unique in-situ film-forming mechanism of the IPN system of the present invention during the heat treatment process. The two prepolymers, epoxy acrylate and blocked polyurethane, react to form a composite structure in which two polymer networks penetrate and entangle each other. Among them, the flexible polyurethane network segments, with their low bending modulus, give the final film layer good flexibility, thereby effectively reducing the overall rigidity of the fabric. At the same time, the physical interlocking structure formed by the two networks can more effectively encapsulate and fix the pigment particles, thereby enhancing the system's ability to resist external mechanical effects.

[0087] In comparison, Comparative Example 2, according to its definition, uses a conventional commercially available self-cross-linking acrylate adhesive. After curing, this type of adhesive can only form a single, rigid acrylate cross-linked network. Due to the lack of the introduction of flexible chain segments, this high-modulus film layer directly leads to a significant increase in the bending stiffness of the fabric, making its physical properties appear stiff. In addition, the single network structure is more likely to produce microscopic damage due to stress concentration under the swelling and external force of repeated washing, resulting in the loss of pigment particles, thereby leading to more significant color changes. Therefore, this comparative experiment verified the comprehensive performance advantages of the IPN system of the present invention compared with conventional technologies from objective data.

[0088] Test Example 3: Quantitative evaluation of physical properties and surface morphology of finished products using step-by-step and mixed printing processes Experimental materials and samples Example 1 Sample: The finished product of the imitation sand-washed gauze prepared according to the steps of the aforementioned "Example 1" (using A and B slurries for step-by-step overprinting).

[0089] Comparative Example 3 sample: a finished product of imitation sand-washed gauze prepared according to the steps of the aforementioned "Comparative Example 3" (mixing all components of slurries A and B and printing them at one time).

[0090] Experimental equipment and consumables: YG002B fabric stiffness tester, non-contact three-dimensional optical profilometer (or equipment with equivalent performance).

[0091] Experimental procedures Fabric softness test (flexural stiffness test) Sample preparation: From the printed areas of the finished fabric samples of "Example 1 Sample" and "Comparative Example 3 Sample", five rectangular samples with a size of 25 mm × 200 mm were cut along the warp and weft directions respectively, and the samples were humidified under standard atmospheric conditions for at least 24 hours before testing.

[0092] Instrument operation: Place the sample flat on the horizontal platform of the stiffness tester, align one end of the sample with the edge of the platform, press the other end of the sample with a pressure block, and then push the platform at a constant speed so that the sample bends along a 41.5-degree slope due to its own weight. When the front end of the sample touches the slope, stop pushing immediately and read the extended length of the sample from the platform scale, which is the bending length (unit: mm). Both the front and back sides of each sample need to be tested.

[0093] Data processing: Calculate the average value of the warp and weft bending lengths of each group of samples respectively, and then calculate the total average bending length. This value is used as an evaluation index. The smaller the value, the lower the rigidity of the fabric, that is, the softer it is.

[0094] Surface 3D topography and roughness analysis This test is designed to quantify the degree of microscopic relief on the surface of the printed area of ​​a sample.

[0095] Sample preparation: 5 samples of about 10 mm × 10 mm in size were cut from the printed areas of the finished fabric samples of "Example 1 Sample" and "Comparative Example 3 Sample", respectively, ensuring that their surfaces were flat.

[0096] Instrument operation: Use a non-contact three-dimensional optical profilometer to randomly select five 1mm×1mm areas on the printed surface of each sample for scanning. The instrument collects surface height data and generates a three-dimensional topography map.

[0097] Data processing: Based on the data collected by the instrument, the arithmetic mean height (Sa) of each scanning area is calculated according to the ISO25178 standard, and the average value of each sample is calculated. This value is used as an evaluation index. The larger the value, the more severe the surface fluctuations and the more obvious the three-dimensional features.

[0098] Test data Table 3: Effects of step-by-step and mixed printing on the physical properties and surface morphology of finished products Sample Group Total average bending length (mm) (average value) Surface roughness Sa (μm) (average value) Example 1 Sample 76.9 5.8 Comparative Example 3 Sample 95.2 1.2 Experimental Summary The test data clearly show that the sample of Example 1 using the step-by-step printing process is superior to the sample of Comparative Example 3 using the mixed printing process in terms of both physical softness and surface texture characteristics. Specifically, the total average bending length value of the sample of Example 1 is smaller, proving that its finished product is softer; at the same time, the surface roughness Sa value of the sample of Example 1 is significantly greater than that of Comparative Example 3, proving that its surface has a more significant microscopic three-dimensional undulating structure.

[0099] This result stems from the "functional layering" design achieved by the step-by-step printing process of the present invention. The first printed basic slurry A mainly penetrates into the gaps between fabric fibers, constructing a soft base and providing basic adhesion, while the superimposed special particle slurry B can be concentrated on the surface of the fabric, so that the functional microcapsules therein can play a role in the most effective position (i.e., the surface) in subsequent processing, thereby generating a clear and three-dimensional surface texture. Moreover, since most of the film-forming materials are concentrated on the surface, the impact on the overall rigidity of the fabric is relatively small.

[0100] In comparison, in Comparative Example 3, all functional components are mixed in a single slurry and printed at one time, resulting in mutual interference and cancellation of functions. The microcapsule particles responsible for forming the surface texture are disorderly embedded in the entire printed film layer, and most of them cannot act on the final surface, resulting in a flat surface morphology and a low Sa value. At the same time, the homogeneous thick film layer formed after all the film-forming materials are mixed with the particles increases the bending stiffness of the fabric as a whole, resulting in an increase in its bending length value. Therefore, the orderly arrangement of different functional components in space through a step-by-step process in the present invention is the key to achieving both softness and a specific surface morphology. Its advantages have been confirmed by the above-mentioned objective quantitative data.

[0101] Test Example 4: Quantitative evaluation of the softness of finished products by pressure-sensitive microcapsules Experimental materials and samples Example 1 Sample: A finished product of imitation sand-washed gauze prepared according to the steps of the aforementioned "Example 1" (adding pressure-sensitive microcapsules to the special particle slurry).

[0102] Comparative Example 4 sample: a finished product of imitation sand-washed gauze prepared according to the steps of the aforementioned "Comparative Example 4" (without adding pressure-sensitive microcapsules to the special particle slurry).

[0103] Experimental equipment and consumables: YG002B fabric stiffness tester (or equipment with equivalent performance).

[0104] Experimental procedures Fabric softness test (flexural stiffness test) Sample preparation: From the printed areas of the finished fabric samples of "Example 1 Sample" and "Comparative Example 4 Sample", five rectangular samples with a size of 25 mm × 200 mm were cut along the warp and weft directions respectively. Before testing, the samples were conditioned under standard atmospheric conditions (temperature 20 ± 2°C, relative humidity 65 ± 4%) for at least 24 hours.

[0105] Instrument operation: Place the sample flat on the horizontal platform of the stiffness tester, align one end of the sample with the edge of the platform, press the other end of the sample with a pressure block, and then push the platform at a constant speed so that the sample bends along a 41.5-degree slope due to its own weight. When the front end of the sample touches the slope, stop pushing immediately and read the extended length of the sample from the platform scale, which is the bending length (unit: mm). Both the front and back sides of each sample need to be tested.

[0106] Data processing: Calculate the average value of the warp and weft bending lengths of each group of samples respectively, and then calculate the total average bending length. This value is used as an evaluation index. The smaller the value, the lower the rigidity of the fabric, that is, the softer it is.

[0107] Test data Table 4: Effect of adding pressure-sensitive microcapsules on the softness of the finished product Sample Group Total average bending length (mm) (average value) Example 1 Sample 76.9 Comparative Example 4 Sample 98.5 Experimental Summary The test data clearly show that the sample of Example 1 with the addition of pressure-sensitive microcapsules is significantly better than the sample of Comparative Example 4 without the addition of pressure-sensitive microcapsules in terms of physical softness. Specifically, the total average bending length value of the sample of Example 1 is significantly smaller. This quantitative indicator directly proves that the bending rigidity of its printed area is lower, that is, the finished product is softer.

[0108] The mechanism of this performance improvement lies in the functional design of the present invention. The slurry in Example 1 contains specially designed pressure-sensitive microcapsules. During the printing process, the 7.5kg / cm 2The pressure exceeds the rupture pressure threshold of the microcapsule, causing its capsule wall to rupture. The softening finishing agent (such as modified silicone) wrapped in the capsule core is released in situ and evenly dispersed into the uncured polymer network. These softener molecules play an internal plasticizing and lubricating role, effectively reducing the modulus of the final cured film layer, thereby giving the product excellent soft properties.

[0109] In contrast, according to its definition, Comparative Example 4 eliminates the addition of pressure-sensitive microcapsules to the slurry. Therefore, although its printing process and adhesive system are exactly the same as those of Example 1, there is a lack of an in-situ release mechanism for the softener during the printing process, and the printed film layer formed does not have the function of internal lubrication. Its bending stiffness is only determined by the physical properties of the IPN polymer network itself, so it exhibits relatively higher rigidity, and its total average bending length measurement value is correspondingly larger. This comparative experiment irrefutably proves that the addition of pressure-sensitive microcapsules and their response under specific pressure are direct and key factors in achieving improved softness of the finished product.

[0110] Test Example 5: Quantitative evaluation of the surface morphology of finished products by thermosensitive microcapsules Experimental materials and samples Example 1 Sample: The finished product of the imitation sand-washing gauze prepared according to the steps of the aforementioned "Example 1" (adding thermosensitive microcapsules to the special particle slurry).

[0111] Comparative Example 5 sample: a finished product of imitation sand-washed gauze prepared according to the steps of the aforementioned "Comparative Example 5" (without adding thermosensitive microcapsules to the special particle slurry).

[0112] Experimental equipment and consumables: non-contact three-dimensional optical profiler (or equipment with equivalent performance).

[0113] Experimental procedures Surface 3D topography and roughness analysis This test is designed to quantify the degree of micro-relief in the printed area of ​​a sample in order to evaluate the distressed texture characteristics.

[0114] Sample preparation: 5 samples of about 10 mm × 10 mm in size were cut from the printed areas of the finished fabric samples of "Example 1 Sample" and "Comparative Example 5 Sample", respectively, to ensure that the sample surfaces were flat.

[0115] Instrument operation: Use a non-contact 3D optical profilometer to randomly select 5 1mm×1mm areas on the printed surface of each sample for scanning. The instrument collects surface height data and generates a 3D topography map.

[0116] Data processing: Based on the collected data, the arithmetic mean height (Sa) of each scanning area is calculated, and the average value of each sample is calculated. This value is the evaluation index. The larger the value, the more severe the surface undulation and the more obvious the three-dimensional features.

[0117] Test data Table 5: Effect of adding thermosensitive microcapsules on the surface morphology of the finished product Sample Group Surface roughness Sa (μm) (average value) Example 1 Sample 5.8 Comparative Example 5 Sample 1.3 Experimental Summary Test data show that the surface morphology of the sample in Example 1, which contains thermosensitive microcapsules, is significantly different from that of the sample in Comparative Example 5, which does not contain thermosensitive microcapsules. Specifically, the surface roughness Sa value of the sample in Example 1 is much greater than that of the sample in Comparative Example 5. This quantitative indicator proves that the sample surface has a measurable microscopic three-dimensional undulating structure, that is, the expected distressed texture.

[0118] The formation mechanism of this texture stems from the functional design of the present invention. In Example 1, during the near-infrared heating and curing stage, the azodicarbonamide (ADC) foaming agent encapsulated inside the thermosensitive microcapsules is thermally decomposed, releasing gases such as nitrogen. These gases generate pressure within the closed capsule cavity, causing microscopic rupture of the microcapsules, forming tiny pits and protrusions on the surface of the IPN network that has not yet been fully cured, thereby constructing a distressed texture that appears irregular on a macro scale.

[0119] In comparison, the formula of Comparative Example 5 does not contain thermosensitive microcapsules. Therefore, when undergoing the same heating and curing process, there is no gas production or physical rupture inside the printed layer, and a smooth IPN polymer cured film is finally formed. The measured surface roughness Sa value is at a lower level. This comparative experiment confirms that the addition of thermosensitive microcapsules and their internal chemical reaction under heat are the reasons for the formation of the distressed surface morphology.

[0120] Test Example 6: Quantitative evaluation of the physical properties of finished products using different thermal curing methods Experimental materials and samples Example 1 Sample: The finished product of the imitation sand-washed gauze prepared according to the steps of the aforementioned "Example 1" (using near-infrared radiation for thermal curing).

[0121] Comparative Example 6 sample: a finished product of imitation sand-washed gauze prepared according to the steps of the aforementioned "Comparative Example 6" (using a conventional hot air oven for heat curing).

[0122] Experimental equipment and consumables: YG002B fabric stiffness tester, non-contact three-dimensional optical profilometer (or equipment with equivalent performance).

[0123] Experimental procedures Fabric softness test (flexural stiffness test) Sample preparation: From the printed areas of the finished fabric samples of "Example 1 Sample" and "Comparative Example 6 Sample", five rectangular samples with a size of 25 mm × 200 mm were cut along the warp and weft directions respectively. Before testing, the samples were conditioned under standard atmospheric conditions (temperature 20 ± 2°C, relative humidity 65 ± 4%) for at least 24 hours.

[0124] Instrument operation: Place the sample flat on the horizontal platform of the stiffness tester, align one end of the sample with the edge of the platform, press the other end of the sample with a pressure block, and then push the platform at a constant speed so that the sample bends along a 41.5-degree slope due to its own weight. When the front end of the sample touches the slope, stop pushing and read the extended length of the sample from the platform scale, which is the bending length (unit: mm). Both the front and back sides of each sample need to be tested.

[0125] Data processing: Calculate the average value of the warp and weft bending lengths of each group of samples respectively, and then calculate the total average bending length. This value is used as an evaluation index. The smaller the value, the lower the rigidity of the fabric, that is, the softer it is.

[0126] Surface 3D topography and roughness analysis This test is designed to quantify the degree of micro-relief in the printed area of ​​a sample in order to evaluate the distressed texture characteristics.

[0127] Sample preparation: 5 samples of approximately 10 mm × 10 mm in size were cut from the printed areas of the finished fabric samples of “Example 1 Sample” and “Comparative Example 6 Sample”, respectively, to ensure that the sample surfaces were flat.

[0128] Instrument operation: Use a non-contact three-dimensional optical profilometer to randomly select five 1mm×1mm areas on the printed surface of each sample for scanning, and the instrument collects surface height data.

[0129] Data processing: Based on the collected data, the arithmetic mean height (Sa) of each scanning area is calculated, and the average value of each sample is calculated. This value is the evaluation index. The larger the value, the more severe the surface undulation and the more obvious the three-dimensional features.

[0130] Test data Table 6: Effects of different thermal curing methods on the physical properties of finished products Sample Group Total average bending length (mm) (average value) Surface roughness Sa (μm) (average value) Example 1 Sample 76.9 5.8 Comparative Example 6 Sample 95.2 2.5 Experimental Summary Test data show that samples prepared using different thermal curing methods have significant differences in two physical indicators: softness and surface morphology. Specifically, the sample of Example 1 using near-infrared curing has a lower bending length value and a higher surface roughness Sa value, proving that this process can simultaneously achieve better softness and a more significant distressed texture.

[0131] This performance is due to the near-infrared (NIR) curing process adopted by the present invention. NIR radiation energy is efficiently absorbed by specific components in the slurry, achieving rapid and concentrated heating of energy. This heating method can quickly reach the decomposition temperature of the thermosensitive microcapsules before the IPN network is completely cross-linked and cured, causing the microcapsules to rupture and form a maximized surface texture. At the same time, due to the short heating time, the heat is concentrated in the printed layer, avoiding long-term baking of the entire fabric substrate, thereby protecting the inherent softness of the cotton fiber.

[0132] In comparison, Comparative Example 6 uses a conventional hot air oven for curing, which is a slow, non-selective bulk heating method with low heat transfer efficiency. It requires a longer heating time for the slurry to reach the curing temperature. During this process, the IPN network has sufficient time to form a relatively dense cross-linked structure before the thermosensitive microcapsules decompose. This cured network will inhibit the surface undulations that can be formed by the rupture of the microcapsules, resulting in a lower final Sa value. In addition, long-term overall heating makes the fabric substrate and the adhesive itself stiffer, resulting in an increase in the bending length value. This comparative experiment confirms that near-infrared curing is a key process link in obtaining the target physical properties.

[0133] Test Example 7: Quantitative evaluation of different thickeners on slurry stability and finished product performance Experimental materials and samples Example 1 Sample and slurry: special particle slurry prepared according to the steps of the aforementioned "Example 1", and the finished product of imitation sand-washed gauze made from the slurry.

[0134] Comparative Example 7 Sample and slurry: a special particle slurry prepared according to the steps of the aforementioned "Comparative Example 7" (using a conventional acrylic thickener), and a finished product of imitation sand-washed gauze made from the slurry.

[0135] Experimental equipment and consumables: rotational viscometer, Y571 type friction color fastness tester, spectrophotometer, YG002B type fabric stiffness tester.

[0136] Experimental procedures Printing paste storage stability test This test is designed to quantify the change in viscosity of a printing paste after static storage.

[0137] Initial measurement: Take the newly prepared slurry of Example 1 and the slurry of Comparative Example 7, respectively, and measure their initial viscosity values ​​using a rotational viscometer at 25° C. and 60 rpm.

[0138] Storage and re-measurement: Seal the two slurries, store them at room temperature for 24 hours, and then measure their viscosity again under exactly the same conditions.

[0139] Data processing: Based on the measured viscosity value, calculate the rate of change of viscosity after 24 hours relative to the initial viscosity. This value is the evaluation index. The smaller the absolute value of the rate of change, the better the storage stability of the slurry.

[0140] Color fastness to wet rubbing test This test is designed to quantify the wet rub resistance of a finished printed area.

[0141] Sample preparation and operation: This test procedure is exactly the same as the “Wet Rubbing Color Fastness Test” in “Test Example 1”, using the sample of Example 1 and the sample of Comparative Example 7 as test objects.

[0142] Data processing: Calculate the wet friction staining color difference ΔE based on the chromaticity value measured by the instrument ★ s. The calculation formula and definition of this indicator are exactly the same as those in "Test Example 1".

[0143] Fabric softness test (flexural stiffness test) This test is designed to quantify the softness of a finished printed area.

[0144] Sample preparation and operation: This test procedure is exactly the same as the “Fabric Softness Test (Bending Rigidity Test)” in “Test Example 6”, using the sample of Example 1 and the sample of Comparative Example 7 as test objects.

[0145] Data processing: According to the bending length value measured by the instrument, the total average bending length is calculated. This value is the evaluation index. The smaller the value, the lower the rigidity of the fabric, that is, the softer it is.

[0146] Test data Table 7: Effects of different thickeners on slurry stability and finished product properties Experimental Summary The test data showed that the type of thickener has a significant impact on the stability of the printing paste and the physical properties of the final product. Specifically, the system of Example 1 using a polyurethane associative thickener showed better storage stability. At the same time, the finished product also had better wet friction color fastness (lower ΔE ★ s value) and softness (lower bending length value).

[0147] This performance advantage stems from the mechanism of action of polyurethane associative thickeners, which associate with polymer particles, pigment particles, etc. in the slurry through the hydrophobic groups at both ends of the molecular chain to form a dynamic, reversible three-dimensional network structure to provide viscosity. This associative network is insensitive to changes in the external environment, thereby ensuring the stability of the slurry viscosity. In addition, since the molecules themselves do not produce rigidity and do not remain as the main film-forming material during the film-forming process, they have little effect on the softness and water resistance of the final cured film.

[0148] In comparison, Comparative Example 7 uses a conventional acrylic thickener, which relies on the electrostatic repulsion of carboxyl groups under alkaline conditions to cause its own long-chain molecules to stretch and swell in water to thicken. This mechanism is highly sensitive to the pH value and electrolyte concentration of the system, and can easily cause the viscosity to change during storage. At the same time, the thickener itself, as a hydrophilic polymer, will remain in the cured film, reducing the water resistance of the film layer and resulting in a decrease in wet friction color fastness. In addition, the stretched rigid long chains will also increase the stiffness of the final film-forming material, resulting in an increase in the bending length value of the finished product. This comparative experiment confirms that the use of a polyurethane associative thickener is a necessary technical choice for obtaining a stable slurry and a high-performance finished product.

[0149] Test Example 8: Quantitative evaluation of the fastness of finished products after silane coupling agent pretreatment Experimental materials and samples Example 1 Sample: The finished product of the imitation sand-washed gauze prepared according to the steps of the aforementioned "Example 1" (including the substrate activation pretreatment).

[0150] Comparative Example 8 sample: a finished product of imitation sand-washed gauze prepared according to the steps of the aforementioned "Comparative Example 8" (excluding substrate activation pretreatment).

[0151] Experimental equipment and consumables: Y571 friction color fastness tester, standard drum washing machine, spectrophotometer (or equipment with equivalent performance), standard friction cotton cloth, standard neutral detergent, and distilled water.

[0152] Experimental procedures Color fastness to wet rubbing test This test is designed to quantify the wet rub resistance of a finished printed area.

[0153] Sample preparation and operation: This test procedure is exactly the same as the “color fastness to wet rubbing test” in “Test Example 1”, using the sample of Example 1 and the sample of Comparative Example 8 as test objects.

[0154] Data processing: Calculate the wet friction staining color difference ΔE based on the chromaticity value measured by the instrument ★ s. The calculation formula and definition of this indicator are exactly the same as those in "Test Example 1".

[0155] Washing resistance test This test is designed to quantify the color change of a sample after multiple wash cycles.

[0156] Sample preparation and operation: This test procedure is exactly the same as the “Washing Resistance Test” in “Test Example 2”, using the sample of Example 1 and the sample of Comparative Example 8 as test objects.

[0157] Data processing: Calculate the color difference of washing resistance based on the color value measured by the instrument The calculation formula and definition of this indicator are exactly the same as those in "Test Example 2".

[0158] Test data Table 8: Effect of silane coupling agent pretreatment on the fastness of finished products Experimental Summary The test data show that the sample of Example 1 pretreated with silane coupling agent is superior to the sample of Comparative Example 8 which is not pretreated in terms of both wet friction color fastness and washing resistance. The specific data are: ΔE ★ s value and The values ​​are significantly lower than those of the samples in Comparative Example 8.

[0159] The improvement in performance can be attributed to the role played by the amino-modified silane coupling agent in the pretreatment step. The silane coupling agent undergoes hydrolysis and condensation on the surface of the cotton fiber, and the highly reactive amino functional groups are grafted onto the cellulose macromolecules through chemical bonds. This grafting transforms the cotton fiber surface, which is originally chemically relatively inert, into an active interface full of chemical reaction sites, providing an anchor point for the chemical bonding of the IPN system in the subsequent printing paste.

[0160] In comparison, the preparation process of Comparative Example 8 omits the substrate activation pretreatment step. The bonding between the printing layer and the gauze substrate relies only on the coating effect of the IPN network physical film formation and the weak intermolecular force. When swollen in water or subjected to repeated mechanical action, the interfacial bonding force between the printing layer and the fiber is insufficient to resist external effects, resulting in peeling of the printing layer or falling off of pigment particles. As a result, the sample of Comparative Example 8 exhibits a large color difference value in the wet friction resistance test and the washing resistance test. This comparative experiment confirms that the pretreatment of silane coupling agent is the basis for improving the comprehensive fastness of the finished paint printing product.

[0161] The examples of this specific embodiment are all preferred embodiments of this application and are not intended to limit the scope of protection of this application. Identical components are represented by the same reference numerals. Therefore, any equivalent changes made based on the structure, shape, and principle of this application should be included in the scope of protection of this application.

Claims

1. A gauze printing imitation sand washing process, characterized in that: The following steps are involved: S1. Activate and pre-treat the gauze substrate to provide a suitable surface for subsequent treatment; S2. Based on the activated pretreated gauze substrate, a split printing paste with interpenetrating network characteristics and dual response function is prepared to enable the paste to better bond with the substrate; S3, applying the prepared split printing paste to the activated pre-treated gauze substrate in a pressure-graded responsive overprinting manner to achieve preliminary construction of the pattern; S4. performing a thermal chain reaction and interpenetrating polymer network construction on the gauze substrate that has completed the pressure-graded responsive overprinting to form a stable printing structure; S5. Purify and shape the gauze constructed through the thermal chain reaction and interpenetrating polymer network to obtain a finished product that meets the requirements.

2. A gauze printing imitation sand washing process according to claim 1, characterized in that: The step S1 comprises: Dipping cotton gauze into an aqueous solution of an amino-modified organosilane coupling agent with a concentration of 10-50 g / L; The padded gauze is dried at 100-120°C for 2-3 minutes to allow the silane coupling agent to react with the hydroxyl groups on the fiber surface to form active amino groups.

3. The gauze printing imitation sand washing process according to claim 1, characterized in that: The split printing paste in step S2 includes: Base slurry: water-based acrylic emulsion containing epoxy groups, added in an amount of 20-40 parts by weight; Special particle slurry: containing 10-20 parts by weight of closed polyurethane prepolymer, 5-15 parts by weight of pressure-sensitive microcapsules, and 5-15 parts by weight of heat-sensitive microcapsules; The wall material of the pressure-sensitive microcapsule is melamine-formaldehyde resin, and the capsule core is hydroxyl-terminated polydimethylsiloxane; The wall material of the thermosensitive microcapsule is methyl methacrylate-acrylonitrile copolymer, and the capsule core contains isododecane, hydroxyethyl cellulose, sodium bicarbonate and polyol active substances.

4. A gauze printing imitation sand washing process according to claim 3, characterized in that: The weight ratio of isododecane, hydroxyethyl cellulose, sodium bicarbonate and polyol active ingredient in the capsule core of the thermosensitive microcapsule is 50-70:5-15:1-5:2-8.

5. The gauze printing imitation sand washing process according to claim 1, characterized in that: In step S3, the scraper pressure of the pressure-graded responsive overprinting is 5-10 kg / cm², the rupture pressure threshold of the pressure-sensitive microcapsule is 4-8 kg / cm², and the rupture temperature threshold of the heat-sensitive microcapsule is 120-140°C.

6. A gauze printing imitation sand washing process according to claim 5, characterized in that: The superimposition overprinting is completed in two steps: The first overprint uses a 100-150 mesh screen to print the base slurry, and the slurry penetration depth is 30-50% of the fiber diameter; The second overprinting uses a 60-100 mesh screen to print a special particle slurry, and the slurry penetration depth covers 80-120% of the base slurry layer.

7. The gauze printing imitation sand washing process according to claim 1, characterized in that: The step S4 comprises: The overprinted gauze is passed through a hot air zone at 135-145°C for 40-70 seconds to deblock the blocked polyurethane prepolymer and release the active -NCO groups; The treated gauze is irradiated with a near-infrared radiation device in the 800-950nm band, with a radiation energy density of 15-35kW / m² for 5-15 seconds, triggering the rupture of the thermosensitive microcapsule wall material; The polyol active substance released from the core of the thermosensitive microcapsule undergoes cross-linking reaction with the -NCO group of the polyurethane prepolymer, the acrylate epoxy group and the amino group on the fiber surface to form a three-dimensional interpenetrating network structure.

8. A gauze printing imitation sand washing process according to claim 7, characterized in that: In the cross-linking reaction, the molar ratio of -NCO group to epoxy group, amino group and polyol is 1:0.3-0.5:0.2-0.4:0.1-0.

3.

9. The gauze printing imitation sand washing process according to claim 1, characterized in that: The step S5 comprises: The heat-treated gauze is soaped in warm water at 40-60°C for 1-2 minutes, then dipped in amino silicone oil softener, and dried at 110-130°C for setting.

10. A gauze printing imitation sand washing process according to claim 9, characterized in that: The padding concentration of the amino silicone oil softener is 20-50 g / L, the padding rate is 70-90%, and the cloth passes through the oven at a speed of 2-5 m / min during drying and shaping.

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