Preparation method of dispersible non-woven fabric and dispersible non-woven fabric

Abstract

The preparation method of the non-woven fabric capable of being dispersed comprises the following steps that S10, a dry base body is formed, and the dry base body comprises a plurality of protruding structures; s20, mist water flow is sprayed to the surface of the dry base body, so that the protruding structures and the areas adjacent to the protruding structures are wetted; s30, the wetted area is dried, so that a fluffy microstructure is formed; s40, the cellulose dry base body is subjected to embossing treatment, continuous wavy-line-shaped embossing in the machine direction is formed, meanwhile, the cleaning efficiency can be improved, especially for cleaning the crissum, the usage amount is reduced so that the user experience can be improved, the wiping and using comfort can be improved, the flushable capacity is high, and the enough strength can meet the production requirement.

Description

TECHNICAL FIELD

[0001] The present application relates to a method for preparing a flushable nonwoven fabric and a flushable nonwoven fabric formed by the method. BACKGROUND

[0002] In the field of personal hygiene and care, the use of wet wipes has become increasingly popular, mainly due to their advantages in terms of cleaning efficiency and user experience. However, despite the wide variety of wet wipe products on the market, existing technical solutions still have significant limitations in meeting consumers' multiple needs. These needs cover multiple dimensions such as thorough cleaning, optimal user comfort, efficient production process, and minimal environmental impact. Current technical means are difficult to meet these key standards at the same time.

[0003] For example, the complex anatomical structure of the perianal region of the human body has many tiny folds and crevices, which poses a huge challenge to the traditional flat surface of the wet wipe. These surfaces often cannot thoroughly clean all hidden areas in one use. Therefore, users have to repeat the wiping to achieve a satisfactory level of cleanliness. Market research and consumer feedback show that an average of three to four wet wipes are needed for each bowel movement to achieve the desired level of hygiene, which is much more than the consumer's expectation of the amount used at a time.

[0004] In addition, there is a fundamental internal conflict between "flushability" and "product strength", i.e. improving flushability usually requires reducing product strength, but reducing product strength will increase the production breakage rate, making production difficult. Generally, the product MDT should be greater than 20N / 50mm in production to meet the basic production needs, and in some production lines, the MDT may need to be greater than or equal to 30N / 50mm.

[0005] Therefore, it is necessary to provide a new technical solution to solve the above technical problems, i.e. to improve cleaning efficiency, especially for the cleaning of the perianal region, reduce the amount of use to improve user experience, wiping comfort, high flushability and sufficient strength to meet production needs. SUMMARY

[0006] The present application provides a method for preparing a flushable nonwoven fabric, comprising the following steps: S10: forming a dry matrix, the dry matrix comprising a plurality of raised structures; S20: spraying a misty water flow on the surface of the dry matrix, so that the raised structures and the areas immediately adjacent to the raised structures are wetted; S30: drying the wetted areas to form a secondary dry matrix with fluffy microstructures; S40: embossing the secondary dried base to form continuous wavy lines of embossing along the machine direction.

[0007] The protruding structure is in the form of a hemisphere, the diameter of the bottom of the protruding structure is 3-6 mm, the height of the protruding structure is 2-3 mm, the distance between adjacent protruding structures is 2-5 mm, the protruding structures are arranged in rows along a first direction, and the rows of protruding structures are arranged in columns along a second direction, the dry base has a length direction, and the first direction is inclined to the length direction.

[0008] The angle between the first direction and the length direction is 20-35°.

[0009] In step S20, a misty water flow is sprayed onto the surface of the dry base by a spraying device, the spraying amount of the misty water flow is 5-40 ml / m2, the average diameter of the droplets in the misty water flow is 20-60 microns, and the total spraying amount of the misty water flow on the surface of the dry base is 0.15-0.45 times the basis weight of the dry base.

[0010] In step S30, the wetted area is dried by hot air penetration drying or hot air impact drying.

[0011] When the wetted area is dried by hot air impact drying, the hot air temperature is 90-110℃, the air speed is 10-15 m / s, the distance from the air outlet to the width of the surface is 50-80 mm, the single-point action time is 5-8 seconds, and the air flow angle is 0-15°.

[0012] In step S40, the wavy line embossing is arranged in groups, each group of wavy line embossing includes a pair of first wavy line embossing arranged in a symmetrical form, the first wavy line embossing includes a concave section in the form of a circular arc and a convex section, the concave sections of the pair of first wavy line embossing are arranged correspondingly, the convex sections of the pair of first wavy line embossing are also arranged correspondingly, and the width of the spacing area formed between the pair of first wavy line embossing continuously changes in the length direction of the embossed base.

[0013] The minimum spacing distance between the pair of first wavy line embossing arranged correspondingly is 4-8 mm, and the maximum spacing distance is 24-42 mm.

[0014] The application also provides the flushable non-woven fabric prepared by the above preparation method.

[0015] Beneficial effects: The embodiment of the present application provides a preparation method of flushable non-woven fabric, comprising the following steps: S10: forming a dry base body, wherein the dry base body comprises a plurality of protruding structures; S20: spraying a misty water flow on the surface of the dry base body, so that the protruding structures and the areas adjacent to the protruding structures are wetted; S30: drying the wetted areas to form fluffy microstructures; S40: embossing the cellulose dry base body to form continuous wavy line embossing along the machine direction, which can improve the cleaning efficiency, especially for the cleaning of the perianal area, reduce the usage amount to improve the user experience, improve the wiping comfort, has high flushable ability and has sufficient strength to meet the production needs. BRIEF DESCRIPTION OF DRAWINGS

[0016] Figure 1 Preparation method of high-basis-weight flushable non-woven fabric according to the embodiment of the present application; Figure 2 Enlarged view of protruding structure on the surface of dry base body; Figure 3 Schematic diagram of embossing form of dry base body; Element symbol: Water needle 11, holding net 12, spraying device 21, hot air impact drying box 31, dry base body 51, protruding structure 511, partially wetted base body 52, secondary dried base body 53, embossed base body 54, wavy line embossing 541, inner concave section 5411, outer convex section 5412, and interval area 5413. DETAILED DESCRIPTION

[0017] Please refer to Figure 1 The overall process of the preparation method of the flushable non-woven fabric according to one embodiment of the present application is shown in Figure 1 The preparation method of the flushable non-woven fabric according to one embodiment of the present application is specifically as follows: S10: forming a dry base body 51, wherein the dry base body 51 comprises a plurality of protruding structures 511.

[0018] The dry base body 51 is formed by the following specific steps: S101: providing fiber raw materials.

[0019] The fiber raw material includes natural fibers and regenerated fibers. The natural fibers can be at least one of wood pulp fibers, bamboo fibers, straw pulp fibers, cane pulp fibers, and cotton pulp fibers. Preferably, the natural fibers are wood pulp fibers with a length ranging from 2 to 4 mm, and the proportion in the fiber mixture is 60-80%. The wood pulp fibers have good hydrogen bond formation ability and mechanical strength, providing basic structural stability for the flushable nonwoven fabric. The regenerated fibers can be lyocell fibers with a length ranging from 8 to 14 mm and a linear density controlled between 1.2 and 1.8 denier, accounting for 20-40%. Lyocell fibers have excellent wet strength and biodegradability, which helps to improve the flushable properties of the product. It can be understood that the length is the average length, and the linear density is the average linear density.

[0020] In addition, the selection of fiber raw materials can be adjusted according to specific application requirements. In addition to wood pulp fibers and lyocell fibers, other types of natural fibers or synthetic fibers can also be added. For example, bamboo fibers have excellent antibacterial properties and biodegradability, making them suitable for medical dressing applications. Cotton fibers have good moisture absorption and comfort, making them suitable for personal care products. As a biodegradable synthetic fiber, polylactic acid fiber can provide specific mechanical properties and degradation characteristics.

[0021] S102: Fiber web formation.

[0022] The fiber web formation process can use wet laying. In the web formation process, the basis weight of the fiber web is controlled in the range of 85-200 grams per square meter, and the web formation speed is maintained at 50-200 meters per minute.

[0023] S103: Hydroentanglement reinforcement.

[0024] The fiber web is reinforced by a hydroentanglement device. The hydroentanglement device is equipped with multiple rows of high-pressure water needle beams, each row of water needle beam is provided with a plurality of water needles 11, the aperture of the water needles 11 is controlled in the range of 0.1-0.15 mm, and the water pressure is set to 20-80 bar. The water needles 11 are arranged in a staggered manner of 3-5 rows to ensure that each area of the fiber web can be uniformly impacted by the hydroentanglement. The impact of high-pressure water flow promotes the entanglement of fibers with each other, forming a stable network structure, and improving the mechanical strength of the flushable nonwoven fabric through the hydroentanglement reinforcement process.

[0025] The hydroentanglement device also includes a supporting net 12, which includes a plurality of recessed portions on the surface of the supporting net 12. It can be understood that the recessed portions correspond to the protruding structures 511. During the hydroentanglement process of the water needles 11, at least part of the fibers are filled into the recessed portions to form the protruding structures 511.

[0026] S104: First drying to form a dry base 51.

[0027] The drying temperature is controlled in the range of 80-140℃, the drying time is 0.5-5min, and the final moisture content should be reduced to 8% or less.

[0028] It can be understood that the protruding structure 511 is formed on the surface of the dry base body 51 after the first drying, please refer to Figure 2 , Figure 2 The protruding structure 511 on the surface of the dry base body 51 is shown, preferably, the protruding structure 511 is hemispherical, the bottom of the protruding structure 511 has a diameter of 3-6mm, and has a height of 2-3mm, the distance between adjacent protruding structures 511 is 2-5mm, and in addition, the protruding structure 511 is distributed in an array on the surface of the dry base body 51.

[0029] Further, the protruding structure 511 is arranged in rows along a first direction, and a plurality of rows of protruding structures 511 are arranged in columns along a second direction, the dry base body 51 has a length direction, then the first direction is inclined to the length direction, it can be understood that the length direction is the MD direction, and the direction perpendicular to the length direction is the CD direction.

[0030] Further, the angle between the first direction and the length direction is 20-35°.

[0031] It can be understood that the size of the protruding structure 511 takes into account the physiological characteristics of the perianal folds of the human body, ensuring that the cleaning can effectively penetrate the folds during wiping, and the time interval ensures sufficient protrusion density to provide cleaning effect, and avoids excessive density leading to fragile structure, and when the protruding structure 511 is arranged in an inclined manner to the MD direction, a diagonal movement is formed during wiping, reducing the probability of fiber falling off the protruding structure 511.

[0032] S20: Spraying a misty water flow on the surface of the dry base body 51, so that the protruding structure 511 and the area adjacent to the protruding structure 511 are wetted to form a partially wet base body 52.

[0033] In the embodiment, a spraying device 21 is used to spray a mist water flow on the surface of the dry base 51. Preferably, the spraying amount of the mist water flow is 5-40 ml / m2, the average diameter of the liquid droplets in the mist water flow is 20-60 microns, and the ratio of the total spraying amount of the mist water flow to the basis weight of the dry base 51 is 0.15-0.45, so that the mist water flow mainly wets the raised structure 511 and the peripheral area of the raised structure 511, and the mist water flow does not soak the dry base 51, thereby preventing the strength of the dry base 51 from greatly decreasing to cause paper breakage in the subsequent processing process. It is found in further research that when the ratio of the total spraying amount to the basis weight of the dry base is greater than 0.45, the strength of the dry base will decrease by more than 40%, so that the structure is damaged or the strength is insufficient during the transfer of the spraying device to the drying device. Meanwhile, because the soaking depth is too deep, the fiber pores are too large in the subsequent drying process, the fibers are scattered with the airflow during the hot air impact drying process, and thus the overall structure is damaged. When the ratio of the total spraying amount to the basis weight of the dry base is less than 0.15, the raised structure 511 cannot be completely soaked due to the insufficient soaking depth, and the strength and dispersibility cannot be met at the same time. Meanwhile, because the water is concentrated on the surface, the raised structure is difficult to rebound under the influence of the wind pressure during the hot air impact drying, so that the raised structure 511 cannot achieve the expected wiping effect.

[0034] It is found that, through the above-mentioned precise local wetting, the hydrogen bonds of the fibers of the raised structure 511 and the adjacent area are selectively broken, so that the original tight structure is loosened, which creates necessary conditions for the subsequent formation of a fluffy microstructure.

[0035] Further, the spraying device 21 can be an ultrasonic atomization array. In another embodiment, the spraying device 21 is a microfluidic jet device. The microfluidic jet device includes a microfluidic chip jet head with a precision nozzle having a diameter of 30-50 microns, which can generate extremely small droplets with a volume of only 8-12 nanoliters. The microfluidic jet device can more accurately control the size and position of the droplets, while maintaining or even improving the uniformity of the wetting effect.

[0036] S30: drying the wetting area to form a secondary dry base 53 with a fluffy microstructure.

[0037] Specifically, the wetting area can be dried by hot air penetration drying or hot air impact drying.

[0038] Specifically, when the drying is hot air penetration drying, the temperature of the drying is controlled in the range of 100-140℃, the time is 1-3 min, and the wind speed is controlled in the range of 2-5 m / s.

[0039] Preferably, the wetted area is dried by hot air impact drying. Specifically, the wetted area can be dried by a multi-nozzle array hot air impact drying box 31.

[0040] During hot air impact drying, the hot air temperature is 90–110℃, the wind speed is 10–15 m / s, the airflow outlet height from the fabric is 50–80 mm, the single-point action time is 5–8 seconds, and the airflow angle is 0–15°. It is understood that a hot air temperature of 90–110℃ is higher than the boiling point of water to accelerate evaporation, but lower than the cellulose decomposition temperature to ensure product quality. A wind speed of 10–15 m / s ensures airflow penetration while reducing damage to the fabric surface or fiber removal. An airflow outlet height of 50–80 mm prevents fiber disturbance and reduces impact force. When the airflow angle is 0°, it is perpendicular to the fabric. Preferably, the airflow angle is 12–15° to enhance the shear force on the raised sides through the tilt angle, promoting fiber fluffiness.

[0041] Furthermore, during hot air impact drying, the width is supported by a conveyor belt, which is a polyester mesh belt with an air permeability of ≤5%.

[0042] Furthermore, in a specific embodiment, the multi-nozzle array hot air impact drying oven 31 includes several nozzles, the nozzles having a diameter of 2-4 mm and a spacing of 8-25 mm, arranged in a hexagonal pattern.

[0043] S40: Embossing is performed on the secondary dried substrate 53 to form a continuous wavy embossed pattern 541 along the length of the dried substrate.

[0044] Understandably, the secondary dried substrate 53 is subjected to embossing treatment to form the embossed substrate 54. Please refer to this as well. Figure 3 ,exist Figure 3 The diagram shows a schematic of the surface of the embossed substrate 54 after embossing treatment. The wavy linear embossing 541 extends along the machine direction, which is the MD direction. The wavy linear embossing 541 is arranged in groups, and each group of wavy linear embossing 541 includes a pair of first wavy linear embossings arranged symmetrically. The first wavy linear embossing includes an arc-shaped concave section 5411 and an arc-shaped convex section 5412. The concave sections 5411 of the pair of first wavy linear embossings are correspondingly arranged, and the arc-shaped convex sections 5412 of the pair of first wavy linear embossings are also correspondingly arranged, so that the width of the gap area 5413 formed between the pair of first wavy linear embossings changes continuously in the length direction of the embossed substrate 54.

[0045] The research finds that by setting the interval area width as 2-3 times of the fiber length, the ends of fibers of different lengths are staggered and overlapped in the interval area to form a continuous capillary network, which significantly reduces the liquid diffusion resistance. Specifically, the minimum interval distance between a pair of first wavy line embossing is set as 4-8 mm to adapt to 2-4 mm wood pulp fibers, preventing excessive accumulation from blocking the channel. The maximum interval distance between a pair of first wavy line embossing is set as 24-42 mm to adapt to 8-14 mm lyocell fibers, avoiding capillary rupture caused by fiber bending. Through this design, the liquid diffusion speed is increased by more than 20%.

[0046] The research finds that: by setting the convex structure 511 and strengthening the loft of the convex structure 511, on the one hand, the convex structure 511 can match the size of the perianal folds, and combined with the oblique arrangement to generate oblique shear force when wiping, deep into the folds to remove dirt, on the other hand, after loft strengthening, the liquid absorption capacity is increased by 20-30%, the dirt adsorption capacity is enhanced, and the soft convex structure 511 does not produce strong scratching feeling on the perianal skin, improving the use comfort, in addition, the soft convex structure 511 further increases the cleaning ability of the folded skin, on the third hand, the wavy line embossing 541 is used to strengthen the structure of the embossing base body 54 to increase the strength, on the fourth hand, the convex structure 511 increases the stress area during water flow impact, so that the convex structure 511 can be easily detached from the embossing base body 54, thereby making the entire embossing base body 54 more easily disintegrate and disperse, the research finds that the above structure can improve the dispersing performance by more than 10%, in addition, the wavy line embossing avoids pressure concentration leading to strength damage, at the same time, the wavy line embossing forms a guide groove on the embossing base body to increase the absorption effect, thereby accelerating the wet wipe liquid infiltration and improving the production efficiency.

[0047] The preparation method of the flushable non-woven fabric will be further described in combination with specific embodiments. Embodiment

[0048] S50: forming a dry base body, the dry base body comprising a plurality of convex structures.

[0049] S501 fiber preparation: 70wt% wood pulp fiber (length 2-4mm) and 30wt% lyocell fiber (length 12mm, linear density 1.4 denier).

[0050] S502 dry base forming: the fiber slurry is evenly laid on the forming wire cloth with a circular protrusion pattern through a wet forming process to form a wet paper sheet. The wet paper sheet is hydroentangled by 5 high-pressure water needle beams: water needle aperture 0.12 mm, water pressure 32 bar, 35 bar, 40 bar, 45 bar, 50 bar, dried by a drying cylinder, temperature 110℃, to reduce the moisture content to below 6%, to form a dry base, the protrusion structure on the dry base is hemispherical, the bottom diameter of the protrusion structure is 4 mm, the height is 2 mm, the distance between adjacent protrusion structures 511 is 3 mm, arranged in an inclined array, the inclination angle is 30°, the inclination angle is the included angle between the extension direction of the row formed by adjacent protrusion structures and the MD direction, the dry base basis weight is 55 g / m2.

[0051] S51: local mist water flow spraying: an ultrasonic atomizing nozzle array is used to spray the dry base, the spraying amount is 15 ml / m2, the average droplet diameter is 30 pm, the distance between the nozzle and the dry base is 10 cm, the total spraying amount is 27% of the basis weight of the dry base.

[0052] S52 drying treatment: the local wetting base treated by water spraying is dried by a hot air impact drying box, hot air temperature: 100℃, air speed: 12 m / s, air outlet distance from the web height: 60 mm, single point action time: 6 seconds, air flow angle: 15°, to form a fluffy microstructure.

[0053] S53 embossing treatment: an embossing roller with a wavy protrusion pattern is used in cooperation with a smooth counter roller for embossing, embossing depth 0.6 mm, minimum interval distance between wavy lines 6 mm, maximum interval distance 28 mm.

[0054] Comparative Example 1: the method shown in CN113718548A.

[0055] Fiber raw material: 70wt% wood pulp fiber, 15wt% lyocell fiber and 5wt% Tencel; Netting equipment: wet netting machine (working width 2.5 m, line speed 100 m / min) Hydroentanglement equipment: 5 rows of high-pressure water needle beams, the jetting pressures are set to 30±2 bar, 35±3 bar, 40±2 bar, 45±3 bar, 50±2 bar respectively.

[0056] Drying equipment: hot air circulating oven (the temperatures of the first, second and third ovens are set to 105±2℃, 120±2℃ and 135±2℃ respectively).

[0057] Comparative Example 2: the method shown in US6749718.

[0058] Fiber composition: 38% NBKP wood pulp, 32% viscose fiber, 30% microfibrillated cellulose (MFC, diameter 0.01 μm, viscosity 6000 mPa·s).

[0059] Example 1, Comparative Example 1 and Comparative Example 2 were tested, and the results are as follows: Parameter Example 1 Comparative Example 1 Comparative Example 2 Test Method Basis Weight 55 g / m2 55 g / m2 55 g / m2 GB / T 451.2-2023 MDT Strength 43 N / 50 mm 44 N / 50 mm 41 N / 50 mm ISO 9073-3 FTTS Dispersion 91% 79% 73% INDA / EDANA GD4 Dispersion Time ≤120s 163s 156s EDANA Dispersion Test Guide Item Example 1 Comparative Example 1 Comparative Example 2 Average Usage 2.6 pieces 3.6 pieces 3.4 pieces

[0060] From the above test and trial, the dispersion performance of Example 1 is increased by 15% and 24% compared with Comparative Example 1 and Comparative Example 2, respectively, while the average usage is reduced by 27% and 23%, respectively, and the MDT strength of Example 1, Comparative Example 1 and Comparative Example 2 is basically the same.

[0061] The above description is only an embodiment of the present application, and does not limit the patent scope of the present application, and any equivalent structure or equivalent process transformation using the content of the specification and drawings, or direct or indirect application in other related technical fields, are also included in the patent protection scope of the present application.

Claims

1. A method for producing a flushable nonwoven fabric, characterized by, The method comprises the following steps: S10: forming a dry base body, wherein the dry base body comprises a plurality of protruding structures; S20: spraying a mist water flow on the surface of the dry base body, so that the protruding structures and the areas adjacent to the protruding structures are wetted; S30: drying the wetted areas to form a secondary dry base body with fluffy microstructures; S40: embossing the secondary dry base body to form wave line-shaped embossing structures continuously along a machine direction.

2. The method for preparing the washable nonwoven fabric as described in claim 1, characterized in that, The protruding structures are in a semispherical shape, the diameter of the bottom of the protruding structures is 3-6 mm, the height of the protruding structures is 2-3 mm, the distance between adjacent protruding structures is 2-5 mm, the protruding structures are arranged in rows along a first direction, and the rows of protruding structures are arranged in columns along a second direction, the dry base body has a length direction, and the first direction is inclined to the length direction.

3. The method for preparing the washable nonwoven fabric as described in claim 2, characterized in that, The angle between the first direction and the length direction is 20-35°.

4. The method for preparing the washable nonwoven fabric as described in claim 2, characterized in that, In step S20, a mist water flow is sprayed on the surface of the dry base body by a spraying device, the spraying amount of the mist water flow is 5-40 ml / m2, the average diameter of the droplets in the mist water flow is 20-60 microns, and the total spraying amount of the mist water flow on the surface of the dry base body is 0.15-0.45 times the basis weight of the dry base body.

5. The method for preparing the washable nonwoven fabric as described in claim 4, characterized in that, In step S30, the wetted areas are dried by hot air penetration drying or hot air impact drying.

6. The method for preparing the washable nonwoven fabric as described in claim 5, characterized in that, When the wetted areas are dried by hot air impact drying, the hot air temperature is 90-110℃, the air speed is 10-15 m / s, the distance between the air outlet and the width of the base body is 50-80 mm, the single-point action time is 5-8 seconds, and the air flow angle is 0-15°.

7. The method for preparing the washable nonwoven fabric as described in claim 6, characterized in that, In step S40, the wave line-shaped embossing structures are arranged in groups, each group of wave line-shaped embossing structures comprises a pair of first wave line-shaped embossing structures arranged in a symmetrical form, wherein the first wave line-shaped embossing structures comprise a concave section in a circular arc shape and a convex section, the concave sections of the pair of first wave line-shaped embossing structures are arranged correspondingly, the convex sections of the pair of first wave line-shaped embossing structures are also arranged correspondingly, so that the width of the interval area between the pair of first wave line-shaped embossing structures continuously changes along the length direction of the embossed base body.

8. The method for preparing the washable nonwoven fabric as described in claim 7, characterized in that, The minimum interval distance between the pair of first wave line-shaped embossing structures arranged correspondingly is 4-8 mm, and the maximum interval distance is 24-42 mm.

9. A flushable nonwoven web, characterized by, The method is prepared by using the method according to any one of claims 1-8.

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