CN116043410B - Unidirectional moisture-conducting non-woven fabric with concave-convex structure and preparation method thereof - Google Patents

Abstract

The invention discloses a unidirectional moisture-conducting nonwoven fabric with a concave-convex structure and a preparation method thereof, and belongs to the technical field of functional nonwoven fabrics. The method comprises: (1) preparing a composite cotton web: opening, combing and laying of degreased cotton fibers to obtain two layers of cotton webs, compounding polyurethane filaments between the two layers of cotton webs by laying, and then compounding the two layers of cotton webs together by hydroentanglement to obtain a composite cotton web, wherein the polyurethane filaments are arranged at intervals in the longitudinal direction of the composite cotton web; (2) preparing a planar cotton web layer: opening, combing and laying of debleached cotton fibers to obtain a planar cotton web layer; (3) alkali shrinkage: alkali shrinkage treatment is performed on the composite cotton web to obtain a concave-convex cotton web layer; (4) stretching: the concave-convex cotton web layer is stretched; (5) hydroentanglement: the planar cotton web layer and the concave-convex cotton web layer in a stretched state are hydroentangled by a jacquard hydroentanglement machine, and the concave-convex cotton web layer is allowed to shrink freely after the hydroentanglement is completed; (6) drying: drying the nonwoven fabric.

Description

One-way moisture-conducting nonwoven fabric with concave-convex structure and preparation method thereof

Technical Field

The invention belongs to the technical field of functional nonwoven fabrics, and particularly relates to a unidirectional moisture-conducting nonwoven fabric with a concave-convex structure and a preparation method thereof.

Background technique

At present, the surface materials of sanitary napkins and diapers on the market generally use non-woven materials such as hot air, spunbond, spunlace (such as cotton spunlace, bamboo fiber spunlace, PLA spunlace or hemp cotton soft spunlace, etc.). These surface materials have their own advantages and disadvantages. For example, spunbond materials have low costs, but poor comfort; hot air materials are more comfortable than spunbond materials, but chemical fibers are prone to skin allergies in people with sensitive skin, and are difficult to degrade and easily cause environmental pollution; cotton spunlace materials have always been popular for their excellent skin-friendliness and softness, but there is a prominent disadvantage: cotton fabrics are easy to fit the skin after absorbing moisture, making the human body feel uncomfortable. Therefore, it is very necessary to develop a pure cotton spunlace nonwoven fabric that can quickly conduct moisture in a single direction and has good comfort.

If the surface of the cotton nonwoven fabric is a concave-convex structure, the presence of the convex part will greatly reduce the contact area between the pure cotton nonwoven fabric and the human skin. At the same time, when there is a lot of liquid, the liquid will be retained in the concave part, which will greatly improve the comfort of the nonwoven fabric. In the prior art, alkali shrinkage treatment can be used to change the internal structure of the fabric, which may form a concave-convex structure. For example, the invention patent with publication number CN111519425A discloses an alkali shrinkage process for pure cotton jersey, which includes the following steps: 1. Pretreatment: pre-treat the pure cotton jersey through an open-width washing machine; 2. Alkali rolling of the pure cotton jersey; 3. Post-finishing processing of the pure cotton jersey; 4. Drying and shaping of the pure cotton jersey: shaping the pure cotton jersey through a shaping machine; and then performing a pre-shrinkage process. The aforementioned alkali shrinkage process is used to improve the dry and wet color fastness and anti-pilling grade of the pure cotton jersey. There is no mention of allowing the fabric to form a concave-convex structure; in addition, for nonwoven fabrics, it has the following problems:

(1) The processing time is long (20-30h), which affects production efficiency;

(2) The alkali concentration is high, making wastewater treatment difficult;

(3) High alkali concentration and long treatment time will affect the strength of nonwoven fabrics, resulting in lower strength;

(4) The treated nonwoven fabric does not have the function of unidirectional moisture conduction.

Summary of the invention

In order to solve the above problems, the present invention provides a unidirectional moisture-conducting nonwoven fabric with a concave-convex structure and a preparation method thereof. The concave-convex structure is provided on both sides to solve the problem that the pure cotton nonwoven fabric absorbs moisture and fits the skin, thereby improving comfort and providing a better user experience. At the same time, the concave-convex structure on both sides has different degrees of concave-convexity, so that it has a unidirectional moisture-conducting function. The technical solution is as follows:

On the one hand, the present invention provides a unidirectional moisture-conducting nonwoven fabric with a concave-convex structure, comprising a concave-convex cotton mesh layer treated with alkali shrinkage and a flat cotton mesh layer not treated with alkali shrinkage, wherein the concave-convex cotton mesh layer is formed by spunlacing two layers of cotton mesh and polyurethane filaments are arranged in a longitudinal direction of the concave-convex cotton mesh layer and the amount of the polyurethane filaments is 1-10% of the weight of the concave-convex cotton mesh layer. The flat cotton mesh layer and the concave-convex cotton mesh layer in a stretched state are spunlaced and reinforced to obtain a nonwoven fabric.

In this patent, the polyurethane fiber is an elastomeric fiber, which has good tensile resilience (the non-woven fabric itself has basically no resilience). After the concave-convex cotton mesh layer is treated with alkali shrinkage, it is compounded with the flat cotton mesh layer without alkali shrinkage treatment under external tension, and then the external force is removed, and the polyurethane fiber rebounds, causing the concave-convex cotton mesh layer to shrink, while driving the flat cotton mesh layer to shrink to a certain extent, and then a fine concave-convex structure appears, and a concave-convex difference is formed between the upper and lower layers. The concave-convex structure of the concave-convex cotton mesh layer is larger, the fiber expansion is larger, the fiber mesh surface density increases, and the gaps between the fibers decrease; the flat cotton mesh layer has not been treated with alkali shrinkage, the crystallinity does not change, the hygroscopic performance is smaller than that of the concave-convex cotton mesh layer, and the concave-convex structure is smaller, the gaps between the fibers are larger, and then the wettability difference and porosity difference are generated in the thickness of the composite non-woven fabric, achieving unidirectional moisture conduction.

That is, this patent adopts multiple methods to jointly realize the unidirectional moisture conduction function; first, alkali shrinkage can carry out a certain debleaching treatment on the cotton web, so that the crystallinity of the two layers of fibers will be different; second, the difference is formed in the physical structure, there are differences in concave and convexity on the concave and convex cotton web layer and the flat cotton web layer, and differences in pores between fibers.

The weight of the concave-convex cotton mesh layer is 20-80g/ ^m2 , the weight of the flat cotton mesh layer is 20-80g/ ^m2 , and the weight difference between the concave-convex cotton mesh layer and the flat cotton mesh layer is less than 10g/ ^m2 . The weight of the cotton mesh constituting the concave-convex cotton mesh layer is 10-40g/ ^m2 .

The polyurethane filaments of the present invention are required to have high elongation, low elastic modulus and high elastic recovery rate. Specifically, the elongation ratio of the polyurethane filaments is 5-7 times; when stretched to 200% of itself, the elastic modulus is 0.04-0.12 g/denier; when stretched to 200% of itself, the elastic recovery rate is 95%-99%.

Preferably, jacquard spunlace is used to compound and reinforce the flat cotton mesh layer and the concave-convex cotton mesh layer in a stretched state. Jacquard spunlace can further enhance the concave-convex effect.

On the other hand, the present invention also provides a method for preparing the aforementioned unidirectional moisture-conducting nonwoven fabric having a concave-convex structure, comprising the following steps:

(1) Preparation of composite cotton web: The degreased cotton fibers are opened, combed and laid to obtain two layers of cotton webs, and the polyurethane filaments are compounded between the two layers of cotton webs by laying, and then the two layers of cotton webs are compounded together by hydroentanglement to obtain a composite cotton web. The polyurethane filaments are arranged at intervals in the longitudinal direction of the composite cotton web.

(2) Preparation of a flat cotton web layer: The debleached cotton fibers are opened, combed, and laid to obtain a flat cotton web layer.

(3) Alkali shrinkage: The composite cotton mesh is subjected to alkali shrinkage treatment to obtain a concave-convex cotton mesh layer.

(4) Stretching: stretching the concave-convex cotton mesh layer.

(5) Hydroentanglement: The flat cotton mesh layer and the concave-convex cotton mesh layer in a stretched state are compounded and reinforced by jacquard hydroentanglement. After the hydroentanglement is completed, the concave-convex cotton mesh layer is allowed to shrink freely.

(6) Drying: Drying the nonwoven fabric treated in step (5) to obtain a product.

Wherein, in step (3), the process of alkali shrinkage treatment is: immersing in 8-10wt% caustic soda solution at room temperature for 10-15 minutes.

Wherein, in step (4), a tensile force of 5-10N is applied to the concave-convex cotton mesh layer for stretching; the stretching force applied to the flat cotton mesh layer is consistent with that in the conventional hydroentanglement process.

Specifically, in step (5), the concave-convex cotton mesh layer is located on the upper layer, the flat cotton mesh layer is located on the lower layer, and the hydroentanglement pressure is 5-30 MPa. During hydroentanglement, the concave-convex cotton mesh layer and the flat cotton mesh layer are stacked up and down.

The beneficial effects brought by the technical solution provided by the present invention are:

(1) The nonwoven fabric obtained by the method has a concave-convex structure on both sides. The alkali shrinkage treatment can prepare the cotton fiber into a concave-convex structure without applying external force, by utilizing the characteristics of cotton fiber swelling when treated with alkali solution and shrinking after washing and drying, so as to solve the defect that pure cotton nonwoven fabric absorbs moisture and fits the skin poorly.

(2) When the structure is concave-convex, the presence of the convex part will greatly reduce the contact area between the pure cotton nonwoven fabric and the human skin. At the same time, when there is a lot of liquid, the liquid will be retained in the concave part, which will greatly improve the comfort of the nonwoven fabric.

(3) Through the wettability gradient and structural gradient, unidirectional moisture conduction is achieved, and the effect of unidirectional moisture conduction is very good. There is a difference in the concave-convex structure between the upper and lower fiber webs. The concave-convex structure of the upper fiber web is larger, and the concave-convex structure of the lower fiber is smaller. At the same time, the concave-convex structure changes the surface density of the fiber web; the surface density of the upper and lower fiber webs is different; at the same time, alkali shrinkage makes the crystallinity of the upper and lower fiber webs different. Then, a wettability gradient and a structural gradient are formed in thickness. The two effects work together to achieve rapid unidirectional moisture conduction of nonwoven fabrics.

(4) In this patent, the alkali shrinkage concentration is low, the alkali shrinkage time is very short, and the strength effect on the nonwoven fabric is very small.

Detailed ways

In order to make the purpose, technical solutions and advantages of the present invention more clear, the present invention is described in further detail below.

Embodiment 1:

Embodiment 1 provides a method for preparing a unidirectional moisture-conducting nonwoven fabric having a concave-convex structure, comprising the following steps:

(1) Preparation of composite cotton web: The degreased cotton fibers were opened, carded and laid to obtain two layers of cotton webs with a grammage of 30 g/ ^m2 . The polyurethane filaments were longitudinally spaced between the two layers of cotton webs by laying, and the two layers of cotton webs were then composited together by hydroentanglement to obtain a composite cotton web.

(2) Preparation of a flat cotton web layer: The debleached cotton fibers are opened, carded and laid to obtain a flat cotton web layer with a grammage of 60 g/ ^m2 .

(3) Alkali shrinkage: The composite cotton mesh is subjected to alkali shrinkage treatment to obtain a concave-convex cotton mesh layer; the process of alkali shrinkage treatment is: immersing in a 10 wt % caustic soda solution at room temperature for 12 minutes.

(4) Stretching: Apply a tensile force of 5-10N to the concave-convex cotton mesh layer for stretching.

(5) Spunlace: A jacquard spunlace machine is used to compound the flat cotton mesh layer and the concave-convex cotton mesh layer in a stretched state through spunlace. After the spunlace is completed, the tension is removed to allow the concave-convex cotton mesh layer to shrink freely.

(6) Drying: Drying the nonwoven fabric treated in step (5) to obtain a product.

Comparative Example 1:

The comparative example provides a method for preparing a conventional non-woven fabric, which comprises: opening, carding and web laying the cotton fibers to obtain a cotton fiber web with a grammage of 120 g/ ^m2 , and then reinforcing the cotton web with water spunlace to obtain a pure cotton water spunlace non-woven fabric.

Comparative Example 2:

Comparative Example 2 provides a method for preparing a double-layer composite non-woven fabric, and its preparation process is basically the same as that of Example 1, except that: the composite cotton web is not subjected to alkali shrinkage and stretching treatment.

Verification Example

The liquid penetration performance and wetting radius test were conducted on Example 1 and Comparative Examples 1-2. The liquid longitudinal diffusion performance test was conducted in accordance with the standard GB/T 24218.13-2010 "Textiles Nonwoven Fabrics Test Methods Part 13: Determination of Multiple Liquid Penetration Time", and the test was conducted using a YG814D liquid penetration meter. The wetting radius test was conducted in accordance with the standard ASTMD1776. The sample was humidified at a temperature of 21°C and a relative humidity of RH65% for 24 hours before being tested. The test performance is shown in Table 1:

Table 1

As can be seen from Table 1, in Example 1, when the liquid is dropped on the front side of the nonwoven fabric, the liquid is quickly diverted to the other side, while the back side does not divert, indicating that it has excellent unidirectional moisture conduction performance and anti-reverse osmosis effect, while the nonwoven fabrics of Comparative Examples 1 and 2 that do not simultaneously meet the conditions of alkali shrinkage and stretching of polyurethane fibers do not have unidirectional moisture conduction performance. At the same time, through the comparison of the lateral diffusion radius, it can be seen that in Comparative Examples 1 and 2, regardless of the front and back sides, the lateral diffusion radius is large and the difference is not large, while the front diffusion radius in Example 1 is only 0.42 cm, and the back diffusion radius is large, indicating that it has excellent unidirectional moisture conduction performance.

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 principle of the present invention should be included in the protection scope of the present invention.

Claims (9)

1. A unidirectional moisture-conducting nonwoven fabric with a concave-convex structure, characterized in that it comprises a concave-convex cotton mesh layer treated with alkali shrinkage and a flat cotton mesh layer not treated with alkali shrinkage, the concave-convex cotton mesh layer is formed by two layers of cotton mesh being compounded by hydroentanglement and there are polyurethane filaments between the two layers of cotton mesh, the polyurethane filaments are arranged at intervals in the longitudinal direction of the concave-convex cotton mesh layer and the amount thereof is 1-10% of the weight of the concave-convex cotton mesh layer, the flat cotton mesh layer and the concave-convex cotton mesh layer in a stretched state are compounded and reinforced by hydroentanglement to obtain a nonwoven fabric; The method comprises the following steps: (1) Preparation of composite cotton web: The degreased cotton fibers are loosened, combed and laid to obtain two layers of cotton webs, polyurethane filaments are compounded between the two layers of cotton webs by laying, and the two layers of cotton webs are compounded together by hydroentanglement to obtain a composite cotton web, wherein the polyurethane filaments are arranged at intervals in the longitudinal direction of the composite cotton web; (2) Preparation of a flat cotton web layer: the debleached cotton fibers are opened, combed and laid to obtain a flat cotton web layer; (3) Alkali shrinkage: the composite cotton web is subjected to alkali shrinkage treatment to obtain a concave-convex cotton web layer; (4) stretching: stretching the concave-convex cotton mesh layer; (5) Spunlace: The flat cotton mesh layer and the concave-convex cotton mesh layer in a stretched state are compounded and reinforced by jacquard spunlace. After the spunlace is completed, the concave-convex cotton mesh layer is allowed to shrink freely; (6) drying: drying the nonwoven fabric treated in step (5) to obtain a product; In step (3), the alkali shrinkage treatment process is: immersing in 8-10wt% caustic soda solution at room temperature for 10-15 minutes. 2. The unidirectional moisture-conducting nonwoven fabric with a concave-convex structure according to claim 1, characterized in that the gram weight of the concave-convex cotton mesh layer is 20-80g/ ^m2 , the gram weight of the flat cotton mesh layer is 20-80g/ ^m2 , and the gram weight difference between the concave-convex cotton mesh layer and the flat cotton mesh layer is less than 10g/ ^m2 . 3 . The unidirectional moisture-conducting nonwoven fabric with a concavo-convex structure according to claim 2 , wherein the cotton mesh constituting the concavo-convex cotton mesh layer has a gram weight of 10-40 g/m ² . 4. The unidirectional moisture-conducting nonwoven fabric with a concave-convex structure according to claim 1 is characterized in that the elongation ratio of the polyurethane filaments is 5-7 times; when stretched to 200% of its own, the elastic recovery rate is 95%-99%. 5. The unidirectional moisture-conducting nonwoven fabric with a concave-convex structure according to claim 1 is characterized in that jacquard water spunlace is used to compound and reinforce the flat cotton mesh layer stack and the concave-convex cotton mesh layer in a stretched state. 6. The method for preparing the unidirectional moisture-conducting nonwoven fabric with a concave-convex structure according to any one of claims 1 to 5, characterized in that the method comprises the following steps: (1) Preparation of composite cotton web: The degreased cotton fibers are loosened, combed and laid to obtain two layers of cotton webs, polyurethane filaments are compounded between the two layers of cotton webs by laying, and the two layers of cotton webs are compounded together by hydroentanglement to obtain a composite cotton web, wherein the polyurethane filaments are arranged at intervals in the longitudinal direction of the composite cotton web; (2) Preparation of a flat cotton web layer: the debleached cotton fibers are opened, combed and laid to obtain a flat cotton web layer; (3) Alkali shrinkage: the composite cotton web is subjected to alkali shrinkage treatment to obtain a concave-convex cotton web layer; (4) stretching: stretching the concave-convex cotton mesh layer; (5) Spunlace: The flat cotton mesh layer and the concave-convex cotton mesh layer in a stretched state are compounded and reinforced by jacquard spunlace. After the spunlace is completed, the concave-convex cotton mesh layer is allowed to shrink freely; (6) Drying: Drying the nonwoven fabric treated in step (5) to obtain a product. 7. The preparation method according to claim 6, characterized in that in step (3), the alkali shrinkage treatment process is: immersing in 8-10wt% caustic soda solution at room temperature for 10-15 minutes. 8. The preparation method according to claim 6, characterized in that, in step (4), a tensile force of 5-10N is applied to the concave-convex cotton mesh layer for stretching. 9. The preparation method according to claim 6 is characterized in that, in step (5), the concave-convex cotton mesh layer is located in the upper layer, the flat cotton mesh layer is located in the lower layer, and the water entanglement pressure is 5-30 MPa.