Method of forming a dispersable substrate

Abstract

The embodiment of the invention provides a method for forming a base material capable of being washed away. The method comprises the steps that S1, a single-layer wet web is formed through a forming device, and S2, the wet web is subjected to spunlace reinforcement; s3, the wet web subjected to spunlace reinforcement is subjected to primary drying, and a primary dry web is formed; s4, wetting liquid is sprayed to the primarily-dried web for wetting to form a wetted web, the wetting liquid comprises 0.2%-3% of PAE, and the moisture content of the primarily-dried web is made to be 10%-13%; s5, performing micro-embossing treatment on the wetted web to form a micro-embossed web; s6, secondary drying is conducted on the micro-embossed web to form a final-dried web, the water content of the final-dried web is 6-9%, through the treatment, more hydroxyl groups are formed on the surface layer to be combined with wood pulp fibers, the wood pulp fibers are fixed, in addition, fiber pores on the surface are actually reduced through micro-embossing, the situation that wood pulp fibers fall off to form falling scraps is further reduced, and the quality of the wood pulp fibers is improved. In addition, through the structural arrangement, the flushability is improved.

Description

Technical Field

[0001] The present invention relates to a method of forming a flushable substrate. Background Art

[0002] In recent years, with the rapid development of the economy, people's pursuit of quality of life has gradually increased, and non-woven products (such as facial masks, face towels, makeup remover towels, wet toilet paper, etc.) have become an important role in daily life. Non-woven fabrics, as a commonly used material for non-woven products on the market, have the advantages of a wide source of raw materials and a soft and fluffy feel. As people's environmental awareness increases, non-woven fabrics are developing in the direction of green and environmental protection, and flushable non-woven materials have come into being.

[0003] Typically, flushable non-woven fabrics include viscose fibers, wood pulp fibers and Tencel. Based on the above fiber composition, there is still a problem of chip shedding in actual use. Currently, documents such as CN101984177A, CN117867752A, and CN117966362A have proposed flushable non-woven fabrics that reduce chip shedding. However, these technical solutions are difficult to apply to existing production equipment or require the addition of special ingredients such as water-soluble gels, making these technical solutions difficult to be widely used.

[0004] Therefore, it is necessary to propose an improved technical solution to solve the above technical problems. Summary of the Invention

[0005] To this end, the present invention provides a method for forming a flushable substrate to solve the above technical problems.

[0006] A method of forming a flushable substrate, comprising: S1: forming a single-layer wet web by a forming device, wherein the single-layer wet web comprises a first fiber layer, a second fiber layer, and a third fiber layer, wherein the first fiber layer comprises 25% to 35% viscose fiber, 8% to 12% tencel, and 55% to 65% wood pulp fiber; the second fiber layer comprises 12% to 18% viscose fiber, 3% to 8% tencel, and 75% to 85% wood pulp fiber; the third fiber layer comprises 25% to 35% viscose fiber, 8% to 12% tencel, and 55% to 65% wood pulp fiber, and the wood pulp fiber in the second fiber layer accounts for more than 75% of the wood pulp fiber in the single-layer web; S2: hydroentanglement of wet webs; S3: performing primary drying on the hydroentangled wet web to form a primary dried web; S4: spraying a wetting liquid on the initially dried web to wet it to form a wetted web, wherein the wetting liquid includes 0.2-3% PAE and makes the moisture content of the initially dried web 10-13%; S5: performing micro-embossing treatment on the wetted web to form a micro-embossed web; S6: performing secondary drying on the slightly embossed web to form a final dried web, wherein the moisture content of the final dried web is 6-9%.

[0007] In step S4, a spraying device sprays the wetting liquid onto the pre-dried web. The spraying device atomizes the wetting liquid to form an atomized area. The pre-dried web passes through the atomized area so that the wetting liquid wets the surface of the pre-dried web.

[0008] Wherein, after the spraying device atomizes the wetting liquid, the wetting liquid forms droplets of 100 to 500 μm in the atomization area.

[0009] The wetting liquid includes a water-soluble adhesive, and the content of the water-soluble adhesive in the wetting liquid is 0.1-2%.

[0010] Wherein, the moisture content of the initially dried web is 7-9%.

[0011] The micro-embossing refers to an embossed pattern formed by indentations with a size of less than 2 mm and a depth of less than 1 mm, and the distribution density of the indentations on the micro-embossed web is greater than 20 / cm².

[0012] The indentation size is 0.8-1.2 mm and the depth is 0.5-0.8 mm. Among them, the forming device includes a slurry box and a forming net, the slurry box includes three slurry flow channels, and the three slurry flow channels are arranged in sequence along the movement direction of the forming net. The three slurry flow channels are respectively the first slurry flow channel, the second slurry flow channel and the third slurry flow channel. The first slurry flow channel receives the first slurry, the second slurry flow channel receives the second slurry and the third slurry flow channel receives the third slurry. The first slurry, the second slurry and the third slurry are formed into the first fiber layer, the second fiber layer and the third fiber layer on the forming net in sequence, and the first fiber layer, the second fiber layer and the third fiber layer are stacked to form a single layer form.

[0013] Among them, the first slurry, the second slurry and the third slurry all include viscose fiber, tencel and wood pulp fiber, among which the ratio of viscose fiber, tencel and wood pulp fiber is: 25-35:8-12:55-65, the ratio of viscose fiber, tencel and wood pulp fiber in the second slurry is: 12-18:3-8:75-85, and the ratio of viscose fiber, tencel and wood pulp fiber in the third slurry is: 25-35:8-12:55-65.

[0014] Among them, the length of viscose fiber is 3 to 8 mm, the length of tencel is greater than 15 mm, and the length of wood pulp fiber is 2 to 3.5 mm.

[0015] Beneficial effect: An embodiment of the present invention provides a method for forming a dispersible substrate, comprising: S1: forming a single-layer wet web by a forming device, wherein the single-layer wet web comprises a first fiber layer, a second fiber layer and a third fiber layer, wherein the first fiber layer comprises 25% to 35% of viscose fibers, 8% to 12% of tencel, and 55% to 65% of wood pulp fibers; the second fiber layer comprises 12% to 18% of viscose fibers, 3% to 8% of tencel, and 75% to 85% of wood pulp fibers; the third fiber layer comprises 25% to 35% of viscose fibers, 8% to 12% of tencel, and 55% to 65% of wood pulp fibers, and the wood pulp fibers in the second fiber layer account for more than 75% of the wood pulp fibers in the single-layer web; S2: hydroentangling the wet web; Solidification; S3: performing primary drying on the spunlace reinforced wet web to form a primary dry web; S4: spraying a wetting liquid on the primary dry web to wet it to form a wet web, wherein the wetting liquid includes 0.2-3% PAE, and the moisture content of the primary dry web is 10-13%; S5: performing micro-embossing treatment on the wet web to form a micro-embossed web; S6: performing secondary drying on the micro-embossed web to form a final dry web, wherein the moisture content of the final dry web is 6-9%. Through the above treatment, more hydroxyl groups are formed on the surface layer to combine with the wood pulp fibers, thereby fixing the wood pulp fibers. In addition, the micro-embossing actually reduces the fiber pores on the surface, further reducing the wood pulp fibers from falling out and forming debris. In addition, the structural arrangement improves the dispersibility. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 The device involved in the method for forming a flushable substrate according to an embodiment of the present invention; Figure 2 for Figure 1 Enlarged schematic diagram of the forming device.

[0017] Description of components in the picture: Forming device 10; forming wire 11; headbox 12; first pulp flow channel 121; second pulp flow channel 122; The third pulp flow channel 123; the water jet head 20; the drying ovens 30, 60; the spraying device 40; and the embossing device 50. DETAILED DESCRIPTION

[0018] Please refer to Figure 1 An embodiment of the present invention provides a method for forming a flushable substrate, which includes the following steps.

[0019] S1: A single-layer wet web is formed by a forming device 10, wherein the single-layer wet web includes a first fiber layer, a second fiber layer and a third fiber layer, wherein the first fiber layer includes 25% to 35% viscose fiber, 8% to 12% tencel, and 55% to 65% wood pulp fiber; the second fiber layer includes 12% to 18% viscose fiber, 3% to 8% tencel, and 75% to 85% wood pulp fiber; the third fiber layer includes 25% to 35% viscose fiber, 8% to 12% tencel, and 55% to 65% wood pulp fiber, and the wood pulp fiber in the second fiber layer accounts for more than 75% of the wood pulp fiber in the single-layer web.

[0020] It can be understood that the proportion of each fiber in the first fiber layer, the second fiber layer and the third fiber layer is the proportion of the fibers in the absolute dry pulp.

[0021] Please refer to Figure 2 ,exist Figure 2 1 shows a forming device 10 used in the present invention, comprising a headbox 12 and a forming wire 11. The forming wire 11 is constructed in an endless ring and is supported and moved by a plurality of rollers, wherein the rollers include a breast roll located upstream of the headbox 12. A portion of the forming wire 11 downstream of the breast roll is arranged to be inclined upward relative to the horizontal direction. This inclined upward section is called a forming section. The headbox 12 is arranged on the upper side of the forming section and applies slurry to the forming section from above. The slurry is dehydrated and formed into a wet web.

[0022] In this embodiment, the flow box 12 includes three slurry flow channels, which are arranged in sequence along the movement direction of the forming section. For the convenience of description, the three slurry flow channels arranged in sequence are respectively referred to as the first slurry flow channel 121, the second slurry flow channel 122 and the third slurry flow channel 123, and the three slurry flow channels are configured to receive the first slurry, the second slurry and the third slurry, that is, the first slurry flow channel 121 receives the first slurry, the second slurry flow channel 122 receives the second slurry and the third slurry flow channel 123 receives the third slurry. The first slurry, the second slurry and the third slurry are formed into the first fiber layer, the second fiber layer and the third fiber layer on the forming mesh 11 in sequence, and the first fiber layer, the second fiber layer and the third fiber layer are stacked to form a single-layer form. It can be understood that the stacked single-layer form is a wet web.

[0023] It can be understood that the first pulp includes viscose fiber, tencel and wood pulp fiber, wherein the ratio of viscose fiber, tencel and wood pulp fiber is: 25-35:8-12:55-65, so that the absolute dry pulp of the formed first fiber layer includes 25-35% viscose fiber, 8%-12% tencel and 55%-65% wood pulp fiber.

[0024] Similarly, the ratio of viscose fiber, tencel and wood pulp fiber in the second slurry is 12-18:3-8:75-85, and the ratio of viscose fiber, tencel and wood pulp fiber in the third slurry is 25-35:8-12:55-65.

[0025] Meanwhile, the wood pulp fibers in the second pulp account for more than 75% of the wood pulp fibers in the first pulp, the second pulp, and the third pulp.

[0026] In addition, the viscose fiber has a length of 3 to 8 mm and a fiber fineness of 1 to 3 dtex. More specifically, the viscose fiber can be ordinary viscose chopped fibers. The ordinary viscose chopped fibers are viscose fiber pulp (pulp of cellulose purified by steaming and other processes) impregnated into alkali cellulose, aged, sulfonated, dissolved, spun and cut into viscose staple fibers, with a degree of polymerization of generally 300 to 400; the strength requirement of the chopped viscose fibers is: ≥1.8cn / dtex.

[0027] The Tencel is also called Lyocell fiber, which is a viscose fiber product made by a tertiary amine oxide-NMMO solvent spinning technology. In this embodiment, the Tencel is short-cut Lyocell fiber with a strength requirement of ≥3.8cn / dtex and a length greater than 15mm.

[0028] The wood pulp fiber is a fiber made from wood. Specifically, the wood pulp fiber is coniferous wood pulp fiber, and the fiber length is 2 to 3.5 mm.

[0029] S2: Hydroentanglement of wet web.

[0030] The wet web is transferred to the spunlace mesh curtain. Along the running direction of the spunlace mesh curtain, multiple spunlace heads 20 spray high-pressure water needles from one side of the spunlace mesh curtain to impact the wet web, so that the fibers therein are entangled. The high-pressure water needles that pass through the wet fiber web are rebounded by the drum cover and impact the wet fiber web again, so that the fibers therein are entangled again to form a base sheet.

[0031] Furthermore, there are 5 to 10 water jet heads 20, each of which is arranged along the width direction of the water jet mesh curtain, and 5 to 10 water jet heads 20 are arranged at intervals along the length direction of the water jet mesh curtain, and sequentially spray high-pressure water needles to impact the wet web.

[0032] S3: performing primary drying on the hydroentangled wet web to form a primary dried web.

[0033] The wet web is sequentially passed through a plurality of ovens 30 to perform primary drying on the wet web. Preferably, the temperature difference between adjacent ovens 30 is greater than or equal to 15°C. In a specific embodiment, the ovens 30 include a first oven, a second oven, and a third oven, wherein the temperature of the first oven is 105±2°C, the temperature of the second oven is 120±2°C, and the temperature of the third oven is 135±2°C.

[0034] Furthermore, a drying cylinder is provided in the drying oven 30, and the embossed substrate is dried by the drying cylinder.

[0035] After passing through several ovens 30, a hot air penetration drying oven is also included. The embossed substrate is subjected to hot air penetration drying in the hot air penetration drying oven, and during the hot air penetration drying process, the hot air temperature is less than or equal to 250°C, and the hot air pressure is less than or equal to 0.1MPa.

[0036] Furthermore, the moisture content of the initially dried web is 7-9%.

[0037] S4: spraying a wetting liquid on the initially dried web to wet it to form a wetted web, wherein the wetting liquid contains 0.2-3% PAE and makes the moisture content of the initially dried web 10-13%.

[0038] The wetting liquid is sprayed onto the pre-dried web by a spraying device 40. Preferably, the spraying device 40 atomizes the wetting liquid to form an atomized area. The pre-dried web passes through the atomized area so that the wetting liquid wets the surface of the pre-dried web.

[0039] Furthermore, after the spraying device 40 atomizes the wetting liquid, the wetting liquid forms droplets of 100 to 500 μm in the atomization area.

[0040] The PAE specifically refers to polyamide polyamine epichlorohydrin resin.

[0041] Furthermore, the wetting liquid may further include a water-soluble binder, specifically carboxymethyl cellulose, polyvinyl alcohol, starch or its derivatives, hydroxypropyl cellulose, sodium alginate, tropol, guar gum, xanthan gum, gum arabic, carrageenan, galactomannan, gelatin, casein, albumin, purulan, polyethylene oxide, dual adhesive components such as, of course, polyvinyl ethyl ether, sodium polyacrylate, sodium polymethacrylate, polyacrylamide, hydroxylated derivatives of polyacrylic acid and polyvinyl pyrrolidone / vinyl pyrrolidone-vinyl acetate copolymer.

[0042] Furthermore, the content of the water-soluble adhesive in the wetting liquid is 0.1-2%.

[0043] S5: performing micro-embossing treatment on the wet web to form a micro-embossed web.

[0044] The wet web can be micro-embossed by the embossing device 50. The micro-embossing refers to an embossing pattern with an indentation size of less than 2 mm and a depth of less than 1 mm formed on the surface of the wet web by the embossing device 50. At the same time, the distribution density of the indentations on the micro-embossed web is greater than 20 / cm². Preferably, the distribution density of the indentations on the micro-embossed web is 25 to 120 / cm², and more preferably, the distribution density of the indentations on the micro-embossed web is 35 to 75 / cm².

[0045] Furthermore, the indentation size is 0.8-1.2 mm, and the depth is 0.5-0.8 mm.

[0046] It can be understood that the embossing device 50 includes an embossing roller group, which includes an embossing roller and a bottom roller. Predetermined embossing protrusions are provided on the embossing roller to form a predetermined micro-embossing pattern on the wetted web. In this embodiment, the embossing roller group can be a point-to-point, point-to-flat or point-to-concave embossing form, which is not limited here.

[0047] S6: performing secondary drying on the slightly embossed web to form a flushable substrate, wherein the flushable substrate has a moisture content of 6-9%.

[0048] During secondary drying, the same apparatus as that for primary drying can be used, i.e., the micro-embossed web is sequentially passed through a plurality of ovens 60. Preferably, the temperature difference between adjacent ovens 60 arranged sequentially is greater than or equal to 15°C. In a specific embodiment, the ovens 60 include a first oven, a second oven, and a third oven, wherein the temperature of the first oven is 105±2°C, the temperature of the second oven is 120±2°C, and the temperature of the third oven is 135±2°C. Similarly, after passing through the plurality of ovens 60, a hot air through drying oven is further included. The embossed substrate is subjected to hot air through drying by passing through the hot air through drying oven. However, during the hot air through drying process, the hot air temperature is less than or equal to 210°C, and the hot air pressure is less than or equal to 0.1 MPa.

[0049] The research found that the above process can bring the following effects: 1. The first fiber layer and the third fiber layer are located on the outside of the flushable substrate. Since the viscose fibers and Tencel fibers, which are longer and easier to be released from the structure, have a higher proportion in the structure, they can be released more easily under the action of water flow, causing them to disintegrate and the entire flushable substrate to be dispersed.

[0050] Second, the surface is moistened and a very small amount of PAE is added and micro-embossed to form more hydroxyl groups on the surface to combine with the wood pulp fibers and fix the wood pulp fibers. In addition, micro-embossing actually reduces the fiber pores on the surface, further reducing the wood pulp fibers from falling out and forming chips.

[0051] The following is further described with reference to specific examples.

[0052] Example 1: S11: A single-layer wet web is formed by a forming device 10, wherein the single-layer wet web includes a first fiber layer, a second fiber layer and a third fiber layer, wherein the first fiber layer includes 30% viscose fiber, 10% tencel, and 60% wood pulp fiber; the second fiber layer includes 15% viscose fiber, 5% tencel, and 80% wood pulp fiber; the third fiber layer includes 30% viscose fiber, 10% tencel, and 60% wood pulp fiber, and the wood pulp fiber in the second fiber layer accounts for 80% of the wood pulp fiber in the single-layer web.

[0053] S12: Hydroentanglement of wet web.

[0054] S13: performing primary drying on the hydroentangled wet web to form a primary dried web, wherein the moisture content of the primary dried web is 8.8%.

[0055] S14: spraying a wetting liquid on the initially dried web to wet it to form a wetted web, wherein the wetting liquid includes 0.8% PAE and makes the moisture content of the initially dried web 11.6%.

[0056] S15: performing micro-embossing on the wetted web to form a micro-embossed web, wherein the micro-embossing has an indentation size of 1 mm, a depth of 0.7 mm, and a distribution density of 35 embossments / cm².

[0057] S16: performing secondary drying on the slightly embossed web to form a flushable substrate, wherein the flushable substrate has a moisture content of 8.3%.

[0058] Comparative Example 1: The flushable substrate prepared by the prior art.

[0059] Comparative Example 2: S21: A single-layer wet web is formed by a forming device 10, wherein the single-layer wet web includes a first fiber layer, a second fiber layer and a third fiber layer, wherein the first fiber layer includes 30% viscose fiber, 10% tencel, and 60% wood pulp fiber; the second fiber layer includes 15% viscose fiber, 5% tencel, and 80% wood pulp fiber; the third fiber layer includes 30% viscose fiber, 10% tencel, and 60% wood pulp fiber, and the wood pulp fiber in the second fiber layer accounts for 80% of the wood pulp fiber in the single-layer web.

[0060] S22: Hydroentanglement of wet web.

[0061] S23: Drying to form a dispersible base material, wherein the dispersible base material has a moisture content of 8.7%.

[0062] That is, in Comparative Example 2, no wetting and micro-embossing treatments were performed.

[0063] The test results of Example 1, Comparative Example 2 and Comparative Example 3 are as follows:

[0064] in, The test method for basis weight is based on the method of GB / T 24218.1-2009 Textiles - Test methods for nonwovens - Part 1: Determination of mass per unit area.

[0065] The test method for thickness refers to the test method of "GB / T 24218.2-2009 Textiles - Nonwovens - Test Methods - Part 2: Determination of Thickness".

[0066] The test method of MDT refers to the test method of "GB / T24218.3-2010 Textiles - Test methods for nonwoven fabrics - Part 3: Determination of breaking strength and elongation at break", in which the sample width is 50mm, the clamp distance is 100mm, and the tensile speed is 100mm / min.

[0067] MDT-wet refers to the 5.2 test method of "GB / T 40181-2021 Test method and evaluation of flushability of disposable sanitary nonwovens", in which the sample width is 50mm, the clamp distance is 100mm, and the tensile speed is 100mm / min.

[0068] The flushability test is carried out with reference to the test steps of the 7 shaking box decomposition test in "GB / T 40181-2021 Test method and evaluation of flushability of disposable sanitary nonwovens".

[0069] The chipping rate 1 refers to the test method of "GB / T 21196.3-2007 Textiles - Determination of abrasion resistance of fabrics by Martindale method - Part 3: Determination of mass loss".

[0070] The dust loss rate 2 refers to the test method of "GB / T 20810-2018 Toilet Paper Appendix B Dust Loss Rate".

[0071] From the above test results, it can be seen that under different test methods, the chip drop rate is significantly improved, and the strength is improved compared to the existing flushable substrate.

[0072] The above description is only an embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structure or equivalent process transformation made by using the contents of the description and drawings of the present invention, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present invention.

Claims

1. A method for forming a disintegrable substrate, characterized in that: include: S1: forming a single-layer wet web by a forming device, wherein the single-layer wet web comprises a first fiber layer, a second fiber layer, and a third fiber layer, wherein the first fiber layer comprises 25% to 35% viscose fiber, 8% to 12% tencel, and 55% to 65% wood pulp fiber; the second fiber layer comprises 12% to 18% viscose fiber, 3% to 8% tencel, and 75% to 85% wood pulp fiber; the third fiber layer comprises 25% to 35% viscose fiber, 8% to 12% tencel, and 55% to 65% wood pulp fiber, and the wood pulp fiber in the second fiber layer accounts for more than 75% of the wood pulp fiber in the single-layer web; S2: hydroentanglement of wet webs; S3: performing primary drying on the hydroentangled wet web to form a primary dried web; S4: spraying a wetting liquid on the initially dried web to wet it to form a wetted web, wherein the wetting liquid includes 0.2-3% PAE and makes the moisture content of the initially dried web 10-13%; S5: performing micro-embossing treatment on the wetted web to form a micro-embossed web; S6: performing secondary drying on the slightly embossed web to form a final dried web, wherein the moisture content of the final dried web is 6-9%.

2. The method according to claim 1, wherein In step S4, a wetting liquid is sprayed onto the pre-dried web by a spraying device. The spraying device atomizes the wetting liquid to form an atomized area. The pre-dried web passes through the atomized area so that the wetting liquid wets the surface of the pre-dried web.

3. The method according to claim 2, wherein After the spraying device atomizes the wetting liquid, the wetting liquid forms droplets of 100 to 500 μm in the atomization area.

4. The method according to claim 2, wherein The wetting liquid includes a water-soluble adhesive, and the content of the water-soluble adhesive in the wetting liquid is 0.1-2%.

5. The method according to claim 1, wherein The moisture content of the initially dried web is 7-9%.

6. The method according to claim 1, wherein The micro-embossing refers to an embossed pattern formed by indentations with a size of less than 2 mm and a depth of less than 1 mm. The distribution density of the indentations on the micro-embossed web is greater than 20 / cm².

7. The method according to claim 6, wherein The indentation size is 0.8-1.2 mm, and the depth is 0.5-0.8 mm.

8. The method according to claim 1, wherein The forming device includes a slurry box and a forming net. The slurry box includes three slurry flow channels, which are arranged in sequence along the movement direction of the forming net. The three slurry flow channels are respectively a first slurry flow channel, a second slurry flow channel and a third slurry flow channel. The first slurry flow channel receives a first slurry, the second slurry flow channel receives a second slurry and the third slurry flow channel receives a third slurry. The first slurry, the second slurry and the third slurry are formed into a first fiber layer, a second fiber layer and a third fiber layer on the forming net in sequence, and the first fiber layer, the second fiber layer and the third fiber layer are stacked to form a single layer.

9. The method according to claim 8, wherein The first slurry, the second slurry and the third slurry all include viscose fiber, tencel and wood pulp fiber, wherein the ratio of viscose fiber, tencel and wood pulp fiber is: 25-35:8-12:55-65, the ratio of viscose fiber, tencel and wood pulp fiber in the second slurry is: 12-18:3-8:75-85, and the ratio of viscose fiber, tencel and wood pulp fiber in the third slurry is: 25-35:8-12:55-65.

10. The method according to claim 9, wherein The length of viscose fiber is 3 to 8 mm, the length of tencel is greater than 15 mm, and the length of wood pulp fiber is 2 to 3.5 mm.

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