Method for producing a composite nonwoven fabric

Abstract

The present application relates to the field of non-woven fabrics, and particularly relates to a preparation method of a composite non-woven fabric, comprising the following steps: in the first step, outputting fibers by using a first carding machine, the fibers pass through a first doffer to form an upper fiber layer, and / or the fibers pass through a second doffer to form a lower fiber layer; in the second step, outputting fibers by using a second carding machine, the fibers pass through a third doffer and / or a fourth doffer to form a middle fiber layer; in the third step, the upper fiber layer, the middle fiber layer and the lower fiber layer are combined in a composite station to form a body, and the ratio of the average porosity of the upper fiber layer and / or the lower fiber layer to the average porosity of the middle fiber layer is (2-10):1; in the fourth step, inputting an oven to perform hot melt bonding, so as to realize mutual bonding of the upper fiber layer, the lower fiber layer and the middle fiber layer to form a bonding part, and the area of the bonding part accounts for 5-100% of the area of the body. The present application solves the problem that the composite non-woven fabric cannot meet the purpose of bearing high molecules and is prone to cause loss of high molecules in the air absorption state.

Description

Technical Field

[0001] This invention relates to the field of nonwoven fabrics, and more particularly to a method for preparing composite nonwoven fabrics. Background Technology

[0002] Currently, as people's living standards improve, their demands for the comfort and functionality of disposable hygiene products are increasing, leading to a surge in demand. Among disposable hygiene products, fluffy nonwoven fabrics are widely used, primarily in core molding. During core molding, fluffy nonwoven fabrics mainly serve to support and embed superabsorbent polymers. For example, Chinese Patent Publication No. CN211512338U discloses a fluffy nonwoven composite core, which is composed of a first covering layer, a hot melt adhesive layer, a first superabsorbent resin layer, a high-fluffy nonwoven fabric layer, a second superabsorbent resin layer, a hot melt adhesive layer, and a second covering layer connected from top to bottom. The high-fluffy nonwoven fabric layer consists of a surface layer, a bottom layer, and an intermediate layer located between the surface and bottom layers. The surface and bottom layers are both long fiber web layers, and the intermediate layer is a mixed fiber web layer or a fluff pulp fiber web layer, connected integrally with the adjacent bottom and surface layers. The mixed fiber web layer has a thermoplastic microfiber web as its skeleton structure, and fluff pulp fibers are fixedly bonded within the thermoplastic microfiber web. The long fiber web layer is a coarse denier fiber web layer, in which the fiber size is 3.0-10.0D and the length is 38-51mm.

[0003] Under current manufacturing processes, both the upper and lower layers of nonwoven fabric use coarse denier fibers. This results in large pores, making the product prone to deformation. This leads to polymer loss during air absorption, resulting in reduced absorption and increased production costs, ultimately altering product quality and decreasing the core's absorbency and diffusion. To address this, a new method is needed to create a novel nonwoven fabric that effectively supports polymers and minimizes their loss during air absorption. Summary of the Invention

[0004] Therefore, in view of the above problems, the present invention proposes a method for preparing composite nonwoven fabric, which solves the problem that the composite nonwoven fabric produced under the existing process conditions cannot meet the purpose of carrying polymers and is prone to polymer loss under the air absorption state.

[0005] To achieve the above objectives, the present invention adopts the following technical solution: a method for preparing composite nonwoven fabric, comprising the following steps:

[0006] The first step involves using a first carding machine to output fibers, which are then passed through a first doffer to form an upper fiber layer, and / or the fibers are passed through a second doffer to form a lower fiber layer.

[0007] The second step involves using a second carding machine to output fibers, which then pass through a third and / or fourth doffer to form an intermediate fiber layer.

[0008] The third step involves the upper fiber layer, the middle fiber layer, and the lower fiber layer being composited at the composite station to form a body, satisfying the ratio of the average porosity of the upper fiber layer and / or the lower fiber layer to the average porosity of the middle fiber layer as (2-10):1.

[0009] The fourth step involves feeding the material into an oven for hot-melt bonding, which bondes the upper fiber layer, lower fiber layer, and middle fiber layer together to form an adhesive portion. The area of ​​the adhesive portion accounts for 5-100% of the total body area.

[0010] Furthermore, the fiber diameter of the upper fiber layer and / or the lower fiber layer is 4-12D.

[0011] Furthermore, the upper fiber layer and / or lower fiber layer have a basis weight of 12-50 gsm.

[0012] Furthermore, the fiber thickness of the intermediate fiber layer is 0.6-2D.

[0013] Furthermore, the intermediate fiber layer has a basis weight of 5-40 gsm.

[0014] Furthermore, the intermediate fiber layer includes a dense region and a sparse region. The dense region accounts for 80-99% of the area of ​​the intermediate fiber layer, and the remaining area is a sparse region. The sparse region has a basis weight of 5-10 gsm, and the dense region has a basis weight of 10-40 gsm.

[0015] Furthermore, when forming the intermediate fiber layer on the third and / or fourth doffer, airflow is added from bottom to top at the corresponding evacuation zone, so that a 1-10mm area on the evacuation zone forms resistance.

[0016] Furthermore, the thickness of the upper fiber layer and / or the lower fiber layer is 4-20 times the thickness of the intermediate fiber layer.

[0017] Furthermore, the body has a basis weight of 15-120 gsm.

[0018] Furthermore, the body has a basis weight of 38-45 gsm.

[0019] By adopting the aforementioned technical solution, the beneficial effects of the present invention are:

[0020] 1. This solution outputs fibers through a second carding machine to form an intermediate fiber layer, which can be a single-layer or double-layer structure. The upper fiber layer, intermediate fiber layer, and lower fiber layer are then bonded together at a composite station to form a main body. This main body is then fed into an oven for heat-melting bonding, achieving mutual adhesion between the upper, lower, and intermediate fiber layers to form an adhesive portion. The area of ​​the adhesive portion accounts for 5-100% of the main body area. Furthermore, the ratio of the average porosity of the upper and / or lower fiber layers to the average porosity of the intermediate fiber layer is (2-10):1, thus allowing polymer particles to enter the upper and lower fiber layers but preventing them from penetrating the intermediate fiber layer.

[0021] 2. The upper and / or lower fiber layers have a fiber thickness of 4-12D and a basis weight of 12-50 gsm. The intermediate fiber layer has a fiber thickness of 0.6-2D and a basis weight of 5-40 gsm. The intermediate fiber layer, with a fiber thickness of 0.6-2D and a basis weight of 5-50 gsm, exhibits a relatively denser state compared to the upper and lower fiber layers. This results in larger pores in the upper and lower fiber layers compared to the intermediate fiber layer. Furthermore, this arrangement allows for a thicker upper and lower fiber layer and a thinner intermediate fiber layer, enabling better storage of polymer particles in the upper and lower fiber layers. The thinner intermediate fiber layer also reduces overall thickness.

[0022] 3. By setting up sparse and dense zones, strip-shaped intervals can be effectively achieved in the nonwoven fabric. That is, the sparse zones form strips to separate the dense zones. This separation is quite noticeable when spreading polymer particles because the basis weight of the upper and / or lower fiber layers in the sparse zones is similar to that of the middle fiber layer, meaning their gaps are close. Furthermore, the basis weight of the upper and / or lower fiber layers in the sparse zones can be set to be slightly less than that of the middle fiber layer, allowing polymer particles to deposit and creating effective vertical pathways. This increases the amount of polymer in the sparse zones, resulting in strip-shaped absorption-enhancing strips after the absorption core is formed. The thickness of the sparse zones is less than that of the dense zones, determined by the degree of accumulation, which facilitates subsequent expansion.

[0023] 4. By utilizing airflow settings, resistance is created in the 1-10mm area of ​​the detached zone. This significantly reduces the number of fibers in the detached zone during the formation of the intermediate fiber layer, thus achieving the formation of the detached zone within the intermediate fiber layer. The airflow magnitude can be adjusted according to actual needs. Since the airflow creates a diffusion effect after being blown out, the airflow outlet should be located in the center of the detached zone. The airflow is not intended to prevent fibers from entering the detached zone, but rather to create an obstruction to reduce fiber entry; its magnitude is actually very small. A better approach is to use a double-layer structure, which will result in a more balanced detached zone.

[0024] 5. The thickness of the upper fiber layer and / or the lower fiber layer is 4-20 times the thickness of the middle fiber layer. This thickness setting can form a better ratio. Attached Figure Description

[0025] Figure 1 This is a schematic diagram of the structure of the present invention;

[0026] Figure 2 This is a flowchart of the molding process of the composite nonwoven fabric of the present invention;

[0027] Figure 3 This is a schematic diagram of the intermediate fiber layer;

[0028] Figure 4 This is a schematic diagram of the structure in which the airflow hole and the evacuation zone work together. Detailed Implementation

[0029] The present invention will now be further described in conjunction with the accompanying drawings and specific embodiments.

[0030] refer to Figure 1 , Figure 3 This embodiment is provided for reference. Figure 1 , Figure 3This embodiment provides a composite nonwoven fabric, including a body 8. The body 8 includes an upper fiber layer 1, a lower fiber layer 2, and an intermediate fiber layer 3 sandwiched between the upper fiber layer 1 and the lower fiber layer 2. The upper fiber layer 1, the lower fiber layer 2, and the intermediate fiber layer 3 are bonded together to form an adhesive portion. The area of ​​the adhesive portion accounts for 5-100% of the area of ​​the body 8. The fiber thickness of the upper fiber layer 1 and / or the lower fiber layer 2 is 4-12D, and the fiber thickness of the intermediate fiber layer 3 is 0.6-2D. D. The intermediate fiber layer 3 includes a dense region 31 and a sparse region 32. The dense region 31 occupies 80-99% of the area of ​​the intermediate fiber layer 3, and the remaining area is the sparse region 32. The upper fiber layer 1 and / or the lower fiber layer 2 have a basis weight of 12-50 gsm, the sparse region 32 has a basis weight of 5-10 gsm, and the dense region 31 has a basis weight of 10-40 gsm. The thickness of the upper fiber layer 1 and / or the lower fiber layer 2 is 4-20 times the thickness of the intermediate fiber layer 3. The sparse regions 32 are distributed in strips on the intermediate fiber layer 3 to separate the dense regions 31. The thickness of the upper fiber layer 1 and / or the lower fiber layer 2 is 6-8 times the thickness of the intermediate fiber layer 3.

[0031] Preferably, the upper and / or lower fiber layers may have a basis weight of 15 gsm, and the intermediate fiber layer has a basis weight of 8-9 gsm. The upper, lower, and intermediate fiber layers are bonded together by heat-melt adhesive, with the bonded area accounting for 80-100% of the body area. The ratio of the average pore size of the upper and / or lower fiber layers to the average pore size of the intermediate fiber layer is (2-5):1, while the average pore size of the upper and / or lower fiber layers in the sparse region is close to that of the intermediate fiber layer. The body has a basis weight of 15-120 gsm. Alternatively, the body may have a basis weight of 38-45 gsm.

[0032] The intermediate fiber layer can be a single-layer structure or a double-layer structure. When the intermediate fiber layer is a double-layer structure, the intermediate fiber layer is staggered and bonded along the conveying direction during the composite process. The length of the staggered bonding is not less than 1 mm, and the optimal length is 5 mm.

[0033] By adopting the aforementioned technical solution, the beneficial effects of the present invention are:

[0034] This solution uses an upper fiber layer, a middle fiber layer, and a lower fiber layer to form a composite. The fiber thickness of the upper and / or lower fiber layers is 4-12D, and the fiber thickness of the middle fiber layer is 0.6-2D. The upper and / or lower fiber layers have a basis weight of 5-50 gsm, and the middle fiber layer has a basis weight of 5-40 gsm. This results in a denser middle fiber layer compared to the upper and lower fiber layers, meaning the pores in the upper and lower fiber layers are larger than those in the middle fiber layer. When this composite nonwoven fabric is used in the molding of an absorbent core, polymer particles are embedded in the upper and lower fiber layers but cannot penetrate the middle fiber layer, thus achieving stable placement of the polymer particles. The fiber thickness and basis weight of the middle fiber layer can be set according to actual needs to meet the performance requirement of preventing specific polymer particles from passing through. Specifically, the upper, middle, and lower fiber layers are loose nonwoven fabrics. Furthermore, by setting up sparse and dense zones, strip-shaped intervals can be effectively achieved in the nonwoven fabric. That is, the sparse zones form strips to separate the dense zones. This separation is quite noticeable when spreading polymer particles, because the basis weight of the upper and / or lower fiber layers in the sparse zones is similar to that of the middle fiber layer, meaning their gaps are close. In fact, the basis weight of the upper and / or lower fiber layers in the sparse zones can be set to be slightly less than that of the middle fiber layer, allowing polymer particles to deposit and creating effective vertical pathways. This also increases the amount of polymer in the sparse zones, resulting in strip-shaped absorption-enhancing strips after the absorption core is formed. Moreover, the thickness of the sparse zones is less than that of the dense zones, determined by the degree of accumulation, which facilitates subsequent expansion. Furthermore, a basis weight of 15 gsm for the upper and / or lower fiber layers, and 8-9 gsm for the middle fiber layer, is a preferred value. Setting these values ​​ensures good flexibility and stability for the upper and / or lower fiber layers and the middle fiber layer, preventing polymer loss. Furthermore, the upper, lower, and middle fiber layers are bonded together using a thermal fusion adhesive, with the bonded area accounting for 80-100% of the body area. This specific area limitation minimizes the deformable space between the upper and middle fiber layers, and between the lower and middle fiber layers, effectively preventing the accumulation of polymer particles within this deformable space. Of course, the arrangement of the bonded portions can also reduce polymer particle mating, such as forming a mesh structure or a continuous polygonal structure. Furthermore, setting the average porosity ratio can effectively target the stable placement of specific polymer particles, and different polymer particles can be added to achieve specific effects.Furthermore, the body has a basis weight of 15-120 gsm, preferably 38-45 gsm, to ensure an appropriate weight.

[0035] See again Figure 2 The molding process of this composite nonwoven fabric includes:

[0036] The first step involves using the first carding machine 91 to output fibers, which are then output through the first doffer 92 to form an upper fiber layer, and / or the fibers are output through the second doffer 93 to form a lower fiber layer.

[0037] The second step involves using the second carding machine 94 to output fibers, which then pass through the third doffer 95 and / or the fourth doffer 96 to form an intermediate fiber layer.

[0038] The third step involves the upper fiber layer, the middle fiber layer, and the lower fiber layer being composited at the composite station 97 to form a body, satisfying the ratio of the average porosity of the upper fiber layer and / or the lower fiber layer to the average porosity of the middle fiber layer as (2-10):1.

[0039] The fourth step involves inputting the material into an oven 98 for hot-melt bonding, thereby bonding the upper fiber layer, lower fiber layer, and middle fiber layer together to form an adhesive part, the area of ​​which accounts for 5-100% of the body area.

[0040] The intermediate fiber can be composed of one or two layers of fiber. When there are two layers of fiber, the two layers of fiber are bonded together by hot melt bonding.

[0041] During the formation of the intermediate fiber layer, a directional spinneret process is used to create sparse and dense zones. The shapes of these zones can be customized according to actual needs, such as... Figure 3 The fibers can be strip-shaped, or they can be S-shaped, diamond-shaped, mesh-like, etc. When forming the sparse zone, airflow is increased at the third and / or fourth doffers, causing the airflow to rise from bottom to top. This effectively creates airflow resistance above the sparse zone, reducing fiber falling into it and thus achieving the formation of the sparse zone. By adjusting the airflow magnitude, the stacking thickness and density of the sparse zone can be adjusted. For example... Figure 3 , 4 As shown, the airflow is emitted from the airflow hole 961, which is elongated. The width A of the airflow hole 961 is less than half the width B of the evacuation zone 32. The distance C between the airflow hole and the edge of the evacuation zone is such that when the airflow is blown out and diffuses outward, it will not obstruct the fiber stacking in the dense zone.

[0042] This solution uses a second carding machine to output fibers, forming an intermediate fiber layer, which can be a single-layer or double-layer structure. The upper, intermediate, and lower fiber layers are then bonded together at a composite station to form a main body. This main body is then fed into an oven for heat-melting bonding, achieving mutual adhesion between the upper, lower, and intermediate fiber layers to form an adhesive portion. The area of ​​the adhesive portion accounts for 5-100% of the main body area. Furthermore, the ratio of the average porosity of the upper and / or lower fiber layers to the average porosity of the intermediate fiber layer is (2-10):1, allowing polymer particles to enter the upper and lower fiber layers but preventing them from penetrating the intermediate fiber layer.

[0043] Although the invention has been specifically shown and described in conjunction with preferred embodiments, those skilled in the art should understand that various changes in form and detail may be made to the invention without departing from the spirit and scope of the invention as defined in the appended claims, all of which shall be within the scope of protection of the invention.

Claims

1. A method for producing a composite nonwoven fabric, characterized by, The method comprises the following steps: In the first step, fibers are output by a first carding machine, and the fibers form an upper fiber layer through a first doffer and / or a lower fiber layer through a second doffer; In the second step, fibers are output by a second carding machine, and the fibers form an intermediate fiber layer through a third doffer and / or a fourth doffer, the intermediate fiber layer comprises a dense area and a sparse area, the dense area accounts for 80-99% of the area of the intermediate fiber layer, and the remaining area is the sparse area, the sparse area has a basis weight of 5 gsm, and the dense area has a basis weight of 10-40 gsm, the sparse area and the dense area are arranged to realize effective passage of the upper and lower layers and increase the amount of macromolecules in the sparse area, so that a strip-shaped absorption enhancement strip is formed after the absorption core is formed; In the third step, the upper fiber layer, the intermediate fiber layer, and the lower fiber layer are combined at a composite station to form a body, and the ratio of the average porosity of the upper fiber layer and / or the lower fiber layer to the average porosity of the intermediate fiber layer is (2-10):1; In the fourth step, an oven is input to perform hot melting and bonding, so as to realize mutual bonding of the upper fiber layer, the lower fiber layer, and the intermediate fiber layer to form a bonding part, and the area of the bonding part accounts for 5-100% of the area of the body.

2. The method of claim 1, wherein: The fiber thickness of the upper fiber layer and / or the lower fiber layer is 4-12D.

3. The method for preparing a composite nonwoven fabric according to claim 2, characterized in that: The upper fiber layer and / or the lower fiber layer has a basis weight of 12-50 gsm.

4. The method of claim 1, wherein: The fiber thickness of the intermediate fiber layer is 0.6-2D.

5. The method for preparing a composite nonwoven fabric according to claim 4, characterized in that: The intermediate fiber layer has a basis weight of 5-40 gsm.

6. The method of claim 1, wherein: When the intermediate fiber layer is formed on the third doffer and / or the fourth doffer, air flow is added from bottom to top at the position corresponding to the sparse area, so that a 1-10 mm area on the sparse area forms resistance.

7. The method for preparing a composite nonwoven fabric according to claim 1, characterized in that: The thickness of the upper fiber layer and / or the lower fiber layer is 4-20 times the thickness of the intermediate fiber layer.

8. The method of claim 1, wherein: The body has a basis weight of 15-120 gsm.

9. The method of claim 8, wherein the composite nonwoven fabric is prepared by the steps of: The body has a basis weight of 38-45 gsm.

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