A method for producing a one-way wetting nonwoven fabric having a wetting gradient

Abstract

The application discloses a preparation method of a one-way wetting nonwoven fabric with a wetting gradient, and belongs to the technical field of nonwoven fabrics. The method comprises the following steps: performing semi-defatting treatment on a cotton web in a first defatting solution containing a composite enzyme and a surfactant to obtain a partially defatted cotton web, the treatment temperature is 50-80 DEG C, the treatment time is 30-40 min, the pH value is 7-8, the concentration of the composite enzyme is 0.2-0.8 g / L, and the concentration of the surfactant is 0.5-2.0 g / L; preparing an undefatted cotton web; performing reinforcement and compounding on the partially defatted cotton web and the undefatted cotton web through hydroentanglement to obtain a nonwoven fabric; performing semi-defatting treatment on the nonwoven fabric in a second defatting solution containing sodium hydroxide and a refining agent, the treatment temperature is 100-110 DEG C, the treatment time is 35-50 min, the concentration of the sodium hydroxide is 0.2-0.8 g / L, and the concentration of the refining agent is 0.5-2.0 g / L; and finally, the product is obtained through water washing and drying treatment.

Description

Technical Field

[0001] This invention belongs to the field of nonwoven fabric technology, and specifically relates to a method for preparing a unidirectional moisture-wicking nonwoven fabric with a wetting gradient. Background Technology

[0002] Currently, the surface materials of sanitary napkins and diapers on the market generally use nonwoven materials such as hot-air spunbond, spunbond, and spunlace (e.g., spunlace cotton, bamboo fiber, PLA, or hemp cotton). Each of these surface materials has its advantages and disadvantages. For example, spunbond is inexpensive but not very comfortable; hot-air spunbond is more comfortable than spunbond, but the chemical fibers can easily cause skin allergies in people with sensitive skin, and it is also difficult to degrade, easily causing environmental pollution; spunlace cotton is loved for its excellent skin-friendliness and softness, but it has a significant drawback—cotton fabric tends to stick to the skin after absorbing moisture, causing discomfort. Therefore, it is essential to develop a pure cotton spunlace nonwoven fabric that can quickly and unidirectionally wick away moisture while providing good comfort.

[0003] For example, patent application number CN201710206970.0 discloses a process for preparing a pure cotton unidirectional moisture-wicking nonwoven fabric, including: lamination, where a hydrophilic cotton web and a water-repellent spunlace nonwoven fabric are laminated together to form a composite cotton web; hydroentangling, where the composite cotton web is reinforced by hydroentangling, and the hydrophilic cotton web fibers and the spunlace nonwoven fabric are entangled and bound together by high-pressure water jets, forming a single unit; and drying and rolling, where the spunlace composite cotton nonwoven fabric is dried and rolled into a roll. The hydrophilic cotton web is prepared using degreased and bleached cotton. The water-repellent spunlace nonwoven fabric has a mesh count of 6-22 meshes and a basis weight of 30-40 g / m². 3 By combining hydrophilic cotton web with water-repellent spunlace nonwoven fabric through hydroentangling, the upper surface of the unidirectional moisture-wicking pure cotton spunlace nonwoven fabric has a mesh skeleton structure that is dry and water-repellent. However, some hydrophilic cotton fibers are brought up from the lower layer by water needles during the processing in the regularly arranged mesh, which accelerates the process of liquid absorption, conduction and dissipation, resulting in better unidirectional moisture wicking effect.

[0004] The applicant encountered the following problems when preparing unidirectional moisture-wicking nonwoven fabrics using the aforementioned method:

[0005] (1) Mesh-like water-repellent mesh needs to be made into special specifications, which is difficult to process;

[0006] (2) Water-repellent mesh cotton spunlace nonwoven fabric needs to be made of undegreased cotton fibers; in some usage scenarios, water-repellent mesh cotton spunlace nonwoven fabric needs to be used in close contact with the human body, and the mesh structure is not smooth enough, resulting in a poor user experience; at the same time, the undegreased nonwoven fabric is not soft enough, resulting in a poor user experience.

[0007] (3) Hydrophilic cotton webs are usually treated with alkali. In order to achieve a better treatment effect, a high concentration of sodium hydroxide solution (about 10 g / L) is required for a long time (usually about 90 min). Long-term alkali treatment can easily damage cotton fibers. The treatment of wastewater with high concentration of sodium hydroxide solution is very difficult.

[0008] (4) Alkali treatment can easily damage fibers, resulting in a rough feel and a poor user experience. Summary of the Invention

[0009] To address the aforementioned problems, this invention provides a method for preparing a unidirectional moisture-wicking nonwoven fabric with a wetting gradient, employing a two-stage semi-degreasing process to achieve unidirectional moisture wicking. The technical solution is as follows:

[0010] This invention provides a method for preparing a unidirectional moisture-wicking nonwoven fabric with a wetting gradient, the method comprising the following steps:

[0011] (1) Partially degreased cotton webs are obtained by partially degreasing them in a primary degreasing solution containing a compound enzyme and a surfactant. The treatment temperature is 50-80℃, the treatment time is 30-40 min, the pH value is 7-8, the concentration of the compound enzyme is 0.2-0.8 g / L, and the concentration of the surfactant is 0.5-2.0 g / L. The compound enzyme consists of alkaline pectinase, neutral cellulase, and keratinase in a mass ratio of 1.5-2.0:2.0-4.0:1.2-1.8. In this step, the enzyme concentration is very low, which has two advantages: firstly, it can achieve partial degreasing treatment, and secondly, it reduces the difficulty of wastewater treatment, resulting in very low COD in the wastewater. In addition, this step is mainly used to remove pectin. The removal of pectin has two functions: firstly, other impurities exist in the pectin skeleton, and removing pectin makes subsequent alkaline treatment easier and improves the effect of alkaline treatment. Secondly, alkali treatment is effective at removing wax but not at removing pectin; enzymatic treatment allows the removal of wax and pectin from the degreased cotton mesh to be controlled within a suitable range.

[0012] Cellulase, pectinase, and cutinase can act on the cellulose, pectin, and waxes of the outermost structure of cotton fibers—the cuticle. Cutinase removes the waxes from the surface of cotton fibers, thereby promoting the penetration of other enzymes into the fiber interior; cellulase breaks down the cellulose in the cuticle into cellobiose and glucose; alkaline pectinase catalyzes the cleavage of the α-1,4 glycosidic bonds of polygalacturonic acid, and hydrolyzes pectin substances. The presence of surfactants improves the degreasing efficiency of the complex enzymes.

[0013] (2) Preparation of undegreased cotton web. This is consistent with conventional techniques.

[0014] (3) Partially degreased cotton web and undegreased cotton web are reinforced and composited by hydroentangling to obtain nonwoven fabric. This is consistent with conventional technology.

[0015] (4) The nonwoven fabric obtained in step (3) is subjected to a semi-degreasing treatment in a secondary degreasing solution containing sodium hydroxide and a refining agent. The treatment temperature is 100-110℃, the treatment time is 35-50 min, the concentration of sodium hydroxide is 0.2-0.8 g / L, and the concentration of the refining agent is 0.5-2.0 g / L. In this step, a very low concentration of sodium hydroxide and a very short treatment time are used, so it has virtually no effect on the strength of the fibers. In addition, although the partially degreased cotton web and the undegreased cotton web were treated with alkali under the same conditions, the partially degreased cotton web had previously undergone enzyme treatment, and the treatment effect of the partially degreased cotton web in this step was better, making the difference between the partially degreased cotton web and the undegreased cotton web more obvious.

[0016] (5) The nonwoven fabric processed in step (4) is washed and dried to obtain the product.

[0017] The weight of the cotton web in this invention is 20-80 g / m². 2 The weight of undegreased cotton mesh is 20-80 g / m². 2 The source of cotton web and undegreased cotton web is: raw cotton fibers obtained through opening, carding, and web laying.

[0018] The surfactant used in this invention is selected from long-chain fatty alcohol polyoxyethylene ethers, alkylphenol polyoxyethylene ethers, polyoxyethylene alkylamines, polyethers, or fatty alcohol polyoxyethylene ethers, etc. Preferably, the surfactant is a fatty alcohol polyoxyethylene ether.

[0019] Preferably, the method provided by the present invention further includes: pre-washing the nonwoven fabric with a refining agent solution before step (4), wherein the pre-washing conditions are: temperature of 50-65℃, time of 20-45 min, and concentration of the refining agent solution of 0.5-2.0 g / L; correspondingly, in step (4), the treatment time is 35-40 min. Pre-washing can further reduce the alkali treatment time and further ensure the strength of the product.

[0020] The refining agent in this invention is selected from a compound of phosphate ester surfactants.

[0021] Specifically, the method for preparing a unidirectional moisture-wicking nonwoven fabric with a wetting gradient provided by the present invention includes the following steps:

[0022] S101: Partially degreased cotton webs are obtained by partially degreasing them in a primary degreasing solution containing a compound enzyme and a surfactant. The treatment temperature is 50-80℃, the treatment time is 30-40 min, the pH value is 7-8, the concentration of the compound enzyme is 0.2-0.8 g / L, the concentration of the surfactant is 0.5-2.0 g / L, and the basis weight of the cotton web is 20-80 g / m². 2 The complex enzyme is composed of alkaline pectinase, neutral cellulase and keratinase in a mass ratio of 1.5-2.0:2.0-4.0:1.2-1.8. The surfactant is selected from long-chain fatty alcohol polyoxyethylene ether, alkylphenol polyoxyethylene ether, polyoxyethylene alkylamine, polyether or fatty alcohol polyoxyethylene ether, etc.

[0023] S102: Preparation of undegreased cotton web; wherein the basis weight of the undegreased cotton web is 20-80 g / m². 2 .

[0024] S103: Nonwoven fabric is obtained by reinforcing and compounding partially degreased cotton web and undegreased cotton web through hydroentangling.

[0025] S104: The nonwoven fabric is pre-washed with a refining agent solution. The pre-washing conditions are: temperature of 50-65℃, time of 20-45 min, and concentration of refining agent solution of 0.5-2.0 g / L.

[0026] S105: The nonwoven fabric is subjected to a semi-degreasing treatment in a secondary degreasing solution containing sodium hydroxide and a refining agent. The treatment temperature is 100-110℃, the treatment time is 35-40 min, the concentration of sodium hydroxide is 0.2-0.8 g / L, and the concentration of the refining agent is 0.5-2.0 g / L.

[0027] S106: The product is obtained by washing and drying nonwoven fabric.

[0028] The refining agent is selected from a compound of phosphate ester surfactants.

[0029] The beneficial effects of the technical solution provided by the embodiments of the present invention are as follows:

[0030] (1) After the upper fiber web is partially degreased, it is combined with the original cotton fiber web and then partially degreased again, so that the upper fiber is further degreased and the lower fiber is less degreased. This creates a wettability gradient in the thickness of the nonwoven fabric and enhances the unidirectional moisture-wicking effect.

[0031] (2) The concentrations of enzyme treatment and alkali treatment are low, and the wastewater treatment is simple.

[0032] (3) The alkali treatment time is short and the concentration is low, so it has little impact on the strength of the fiber.

[0033] (4) The alkali treatment time is short, both sides of the product are smooth, the friction is small, and the user experience is good.

[0034] (5) The side of the undegreased cotton mesh is partially degreased, with low moisture absorption and a smoother surface, making it drier and smoother when used on the face. Detailed Implementation

[0035] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be described in further detail below.

[0036] Example 1:

[0037] Example 1 provides a method for preparing a unidirectional moisture-wicking nonwoven fabric with a wetting gradient, the method comprising the following steps:

[0038] (1) The weight obtained after opening, combing, and web laying is 60 g / m². 2 Partially degreased cotton webs were obtained by partially degreasing raw cotton webs in a primary degreasing solution containing a compound enzyme and a surfactant. The treatment temperature was 50℃, the treatment time was 35 min, the pH value was 7-8, the concentration of the compound enzyme was 0.6 g / L, and the concentration of the surfactant was 1.5 g / L. The compound enzyme consisted of alkaline pectinase, neutral cellulase, and keratinase in a mass ratio of 2.0:4.0:1.8.

[0039] (2) Prepare undegreased cotton web with a basis weight of 60 g / m. 2 .

[0040] (3) Partially degreased cotton web and undegreased cotton web are reinforced and composited by hydroentangling to obtain nonwoven fabric.

[0041] (4) The nonwoven fabric is pre-washed with a refining agent solution. The pre-washing conditions are: temperature of 60℃, time of 30min, and concentration of refining agent solution of 1.0g / L.

[0042] (5) The nonwoven fabric obtained in step (4) is subjected to a semi-degreasing treatment in a secondary degreasing solution containing sodium hydroxide and a refining agent. The treatment temperature is 100-110℃, the treatment time is 40min, the concentration of sodium hydroxide is 0.5g / L, and the concentration of the refining agent is 1.5g / L.

[0043] (6) The nonwoven fabric processed in step (5) is washed and dried to obtain the product.

[0044] Comparative Example 1:

[0045] Comparative Example 1 provides a method for preparing a common nonwoven fabric, which includes the following steps: opening, carding, and web-laying degreased cotton fibers to obtain a basis weight of 120 g / m². 2The cotton fiber web is reinforced by hydroentangling to obtain a fully degreased hydroentangled nonwoven fabric.

[0046] Comparative Example 2:

[0047] Comparative Example 2 provides a method for preparing a semi-degreased nonwoven fabric based on a biocomposite enzyme, the method comprising the following steps:

[0048] (1) The weight obtained after opening, combing, and web laying is 60 g / m². 2 The raw cotton fiber web was partially degreased by undergoing a semi-degreasing treatment in a primary degreasing solution containing a compound enzyme and a surfactant. The treatment temperature was 50℃, the treatment time was 35 min, the pH value was 7-8, the concentration of the compound enzyme was 0.6 g / L, and the concentration of the surfactant was 1.5 g / L. The compound enzyme consisted of alkaline pectinase, neutral cellulase and keratinase in a mass ratio of 2.0:4.0:1.8.

[0049] (2) The obtained degreased cotton web is subjected to hydroentanglement reinforcement treatment and then washed and dried to obtain the product.

[0050] Comparative Example 3:

[0051] Comparative Example 3 provides a method for preparing an alkali-treated semi-degreased nonwoven fabric, the method comprising the following steps:

[0052] (1) The weight obtained after opening, combing, and web laying is 60 g / m². 2 The raw cotton fiber web is first pre-washed with a refining agent, and then semi-degreased in a degreasing solution containing sodium hydroxide and a refining agent. The treatment temperature is 100-110℃, the treatment time is 45min, the concentration of sodium hydroxide is 0.5g / L, and the concentration of the refining agent is 1.5g / L.

[0053] (4) The obtained degreased cotton web is subjected to hydroentanglement reinforcement treatment and then washed and dried to obtain the product.

[0054] Comparative Example 4:

[0055] Comparative Example 4 provides a method for preparing ordinary raw cotton nonwoven fabric, the steps of which include: opening, carding and web-laying raw cotton fibers to obtain a basis weight of 60 g / m². 2 The raw cotton fiber web is then hydroentangled to obtain raw cotton hydroentangled nonwoven fabric.

[0056] Verification Example

[0057] Liquid penetration performance, wetting radius, and bursting strength were tested for Example 1 and Comparative Example 1. Liquid penetration performance was tested according to standard GB / T 24218.13-2010 "Textiles - Nonwovens - Test Methods - Part 13: Determination of Multiple Penetration Times of Liquids", using a YG814D liquid penetration meter. Wetting radius testing was performed according to standard ASTM D1776, after conditioning the samples at 21°C and 65% RH for 24 hours. Bursting strength testing was performed according to standard GB / T 19976—2005 "Textiles - Determination of Bursting Strength - Steel Ball Method", using a strength meter. The test performance is shown in Table 1.

[0058] Table 1

[0059]

[0060] As shown in Table 1, compared to the raw cotton nonwoven fabric in Comparative Example 1, the liquid on the nonwoven fabric obtained in Example 1 can flow unidirectionally from the front to the back, with a significant difference in wetting radii between the front and back sides, indicating superior unidirectional moisture conduction performance. Furthermore, compared to the raw cotton nonwoven fabric in Comparative Example 1, the bursting strength of the nonwoven fabric in Example 1, which underwent partial degreasing treatment, decreased, indicating that the partial degreasing treatment causes some damage to the strength of the cotton nonwoven fabric, but the damage is very small and negligible.

[0061] Semi-degreasing effect verification

[0062] The pectin content and cotton wax content of the nonwoven fabrics prepared in Comparative Examples 2-4 were tested, and the test methods are shown below:

[0063] 1. Pectin removal rate: The ammonium oxalate extraction-carbazole colorimetric method was used: 1.5g of dry cotton spunlace nonwoven fabric was weighed, cut into small pieces, and placed in a 250mL flask. 100mL of 0.5% ammonium oxalate solution was added, a condenser was attached, and the mixture was boiled in a boiling water bath for 1.5h. After filtration, 2mL of the filtrate was added to 12mL of concentrated H2SO4 and cooled with ice water. The mixture was then boiled in a boiling water bath for 10min and cooled with cold water at 0℃. Finally, 1mL of 0.15% carbazole anhydrous ethanol solution was added, mixed well, and allowed to stand for 30min. The absorbance was measured at a wavelength of 530nm using a 721 spectrophotometer. The mass fraction of galacturonic acid was calculated from the standard curve, thus obtaining the mass fraction of pectin.

[0064] 2. Cotton Wax Removal Rate: Weigh 10g (accurate to 0.0001g) of a sample that has been shredded and pre-dried to constant weight in an oven at 105℃. Place the sample in a paper tube made of filter paper, which is then placed in a fat extractor. The height of the tube should be 1-1.5 cm above the top of the siphon tube of the extractor, and the height of the sample in the filter paper tube should be 1-1.5 cm below the top of the siphon tube. Add 120mL of carbon tetrachloride to the flask of the fat extractor, place it in a constant temperature water bath, adjust the temperature, and maintain the solvent siphon circulation 3-4 times per hour. After extraction for 3 hours, cool the flask and filter the extract containing waxy substances into a pre-weighed Erlenmeyer flask. Wash the filter paper and funnel of the extractor flask three times with solvent and distill them in a water bath. After all the solvent has evaporated, place the Erlenmeyer flask in an oven and dry it to constant weight at 105℃. After cooling in a dry oven, weigh it accurately.

[0065] The test results are shown in Table 2:

[0066] Table 2

[0067]

[0068] As shown in Table 2, the pectin and wax content of the cotton nonwoven fabric treated with bio-enzymes decreased, with a pectin removal rate of 29% and a wax removal rate of 23%. The pectin removal rate of the cotton nonwoven fabric treated with alkali was 40%, and the wax removal rate was 51%. The removal rates of pectin and wax in the alkali-treated cotton nonwoven fabric were higher than those in the bio-enzyme-treated fabric, and the removal rates for pectin and wax were inconsistent. Furthermore, Table 2 shows that neither of the two degreasing processes in this patent completely removed pectin and wax, retaining a certain amount, resulting in better gloss and smoother texture in the product. Testing showed that the pectin and wax removal rates of the product in Example 1 were both less than 75% (generally, degreasing treatments can achieve a removal rate of up to 80%), retaining a certain amount of pectin and wax.

[0069] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing a unidirectional moisture-wicking nonwoven fabric with a wetting gradient, characterized in that, Includes the following steps: (1) Partially degreased cotton web is obtained by partially degreasing cotton web in a primary degreasing solution containing compound enzyme and surfactant. The treatment temperature is 50-80℃, the treatment time is 30-40min, the pH value is 7-8, the concentration of compound enzyme is 0.2-0.8g / L, and the concentration of surfactant is 0.5-2.0g / L. The compound enzyme is composed of alkaline pectinase, neutral cellulase and keratinase in a mass ratio of 1.5-2.0:2.0-4.0:1.2-1.

8. (2) Preparation of undegreased cotton web; (3) Partially degreased cotton web and undegreased cotton web are reinforced and composited by hydroentangling to obtain nonwoven fabric; (4) The nonwoven fabric obtained in step (3) is subjected to a semi-degreasing treatment in a secondary degreasing solution containing sodium hydroxide and a refining agent. The treatment temperature is 100-110℃, the treatment time is 35-50min, the concentration of sodium hydroxide is 0.2-0.8g / L, and the concentration of the refining agent is 0.5-2.0g / L. (5) The nonwoven fabric processed in step (4) is washed and dried to obtain the product.

2. The method for preparing a unidirectional moisture-wicking nonwoven fabric with a wetting gradient according to claim 1, characterized in that, The weight of the cotton web is 20-80 g / m. 2 The weight of the undegreased cotton web is 20-80 g / m². 2 The cotton web and undegreased cotton web are obtained from raw cotton fibers through opening, carding and web laying.

3. The method for preparing a unidirectional moisture-wicking nonwoven fabric with a wetting gradient according to claim 1, characterized in that, The surfactant is selected from long-chain fatty alcohol polyoxyethylene ethers, alkylphenol polyoxyethylene ethers, polyoxyethylene alkylamines, polyethers, or fatty alcohol polyoxyethylene ethers.

4. The method for preparing a unidirectional moisture-wicking nonwoven fabric with a wetting gradient according to claim 1, characterized in that, The surfactant is a fatty alcohol polyoxyethylene ether.

5. The method for preparing a unidirectional moisture-wicking nonwoven fabric with a wetting gradient according to claim 1, characterized in that, The method further includes: before step (4), the nonwoven fabric is pre-washed with a refining agent solution. The pre-washing conditions are: temperature of 50-65℃, time of 20-45 min, and concentration of refining agent solution of 0.5-2.0 g / L. Correspondingly, in step (4), the treatment time is 35-40 min.

6. The method for preparing a unidirectional moisture-wicking nonwoven fabric with a wetting gradient according to claim 5, characterized in that, The refining agent is selected from a compound of phosphate ester surfactants.

7. The method for preparing a unidirectional moisture-wicking nonwoven fabric with a wetting gradient according to claim 1, characterized in that, Includes the following steps: S101: Partially degreased cotton web is obtained by partially degreasing cotton web in a primary degreasing solution containing a compound enzyme and a surfactant. The treatment temperature is 50-80℃, the treatment time is 30-40 min, the pH value is 7-8, the concentration of the compound enzyme is 0.2-0.8 g / L, the concentration of the surfactant is 0.5-2.0 g / L, and the basis weight of the cotton web is 20-80 g / m². 2 The complex enzyme is composed of alkaline pectinase, neutral cellulase and keratinase in a mass ratio of 1.5-2.0:2.0-4.0:1.2-1.8, and the surfactant is selected from long-chain fatty alcohol polyoxyethylene ether, alkylphenol polyoxyethylene ether, polyoxyethylene alkylamine, polyether or fatty alcohol polyoxyethylene ether. S102: Prepare undegreased cotton web, wherein the basis weight of the undegreased cotton web is 20-80 g / m². 2 ; S103: A nonwoven fabric is obtained by reinforcing and compounding partially degreased cotton web and undegreased cotton web through hydroentangling; S104: The nonwoven fabric is pre-washed with a refining agent solution. The pre-washing conditions are: temperature 50-65℃, time 20-45 min, and concentration of refining agent solution 0.5-2.0 g / L. S105: The nonwoven fabric is subjected to a semi-degreasing treatment in a secondary degreasing solution containing sodium hydroxide and a refining agent. The treatment temperature is 100-110℃, the treatment time is 35-40 min, the concentration of sodium hydroxide is 0.2-0.8 g / L, and the concentration of the refining agent is 0.5-2.0 g / L. S106: The product is obtained by washing and drying nonwoven fabric; The refining agent is selected from a compound of phosphate ester surfactants.

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