Double-layer slow-absorption spunlace material and preparation method thereof

Abstract

The invention discloses a double-layer slow-absorption spunlace material and a preparation method thereof, and belongs to the technical field of non-woven materials. The surface density of the material is 50-120 g / m, the material is formed by compounding a hydrophilic layer and a hydrophobic layer on line, and a liquid absorption channel is arranged between the hydrophilic layer and the hydrophobic layer. The hydrophilic layer accounts for 50-70% and is composed of plant pulp and / or regenerated cellulose fibers; and the hydrophobic layer accounts for 30-50% and is composed of hydrophobic fibers such as terylene and polypropylene fiber. The liquid absorption channels are distributed on the surface of the hydrophobic layer in a dotted or linear mode, the area proportion is 5-20%, the width is 2-8 mm, the thickness of the channels is 60-90% of the thickness of the material, and a downward concave structure is formed. During preparation, after the two layers of fiber webs are overlapped, the fiber webs are reinforced by multiple spunlaces under specific pressure, and a liquid absorption channel is formed by adopting a patterned water needle during the last spunlacing process of the hydrophilic surface, so that a chemical adhesive does not need to be used. The controllable slow absorption function is achieved, water on the surface of food can be prevented from being excessively absorbed while flow is effectively guided, the production cost is low, safety is high, and the slow absorption film is particularly suitable for the field of food packaging of fresh meat pads and the like.

Description

Technical Field

[0001] This invention relates to the field of nonwoven materials technology, and mainly to a double-layer slow-absorbing hydroentangled material and its preparation method. Background Technology

[0002] Food liners, especially those for fresh meat, need to absorb the moisture released from food to keep it fresh. At the same time, the absorbed moisture also slows down bacterial growth and delays spoilage. Existing food liners are structurally divided into two types: single-layer and double-layer. Single-layer liners, especially those made with absorbent polymers like SAP, are specifically designed for high-absorption applications. However, when used for low-absorption situations, the rapid and excessive absorption of liquids can cause the food to lose moisture, affecting its texture and taste.

[0003] Currently, commercially available double-layer mat materials are typically manufactured using "offline lamination" methods such as adhesive bonding or hot pressing. However, this offline lamination process has significant drawbacks: First, it requires additional production steps (such as adhesive application, lamination, and curing), leading to a significant increase in production costs; second, the use of adhesives may introduce chemical substances, posing a potential migration risk and requiring higher safety standards for food contact materials; third, the lamination interface may delaminate due to uneven adhesion, affecting the structural integrity and reliability of the material.

[0004] Therefore, there is an urgent need to develop a new type of double-layer pad material that can effectively control the liquid absorption rate, preserve the taste of food, and achieve safe and low-cost online production. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of the existing technology and provide a double-layer slow-absorbing hydroentangled material and its preparation method. By online composite of a hydrophilic layer and a hydrophobic layer, and then hydroentanglement to form liquid absorption channels on the material surface, the problem of excessively fast liquid absorption and high cost of existing fresh meat pads is solved.

[0006] To achieve the above-mentioned objectives, the technical solution provided by this invention is as follows: In a first aspect, the present invention provides a double-layer slow-absorbing hydroentangled material, the material having an areal density of 50 g / m³. 2 ~120g / m 2 The material consists of a hydrophilic layer and a hydrophobic layer, with liquid absorption channels existing between them. The hydrophilic layer accounts for 50%–70% of the total mass of the material, and the hydrophobic layer accounts for 30%–50%. The area of ​​the liquid absorption channels on the hydrophobic layer accounts for 5%–20% of the surface area of ​​the hydrophobic layer, and the width of the liquid absorption channels is 2–8 mm. The liquid absorption channels contain both hydrophobic and hydrophilic layer materials, wherein the ratio of hydrophilic fibers to hydrophobic fibers is between 1:5 and 1:3.

[0007] Preferably, the hydrophobic layer is composed of hydrophobic fibers, which are one or more of the following: polyester, polypropylene, PE / PET fiber, PE / PP fiber, hydrophobically treated lyocell or viscose fiber.

[0008] Preferably, the hydrophilic layer material is one or a combination of two fibers selected from plant pulp and regenerated cellulose short fibers. The plant pulp includes hardwood pulp, softwood pulp, cotton pulp, hemp pulp, and bamboo pulp. The regenerated cellulose fiber is one or a combination of viscose fiber, lyocell fiber, and modal fiber, with a length of 3–15 mm.

[0009] Preferably, the liquid absorption channels are distributed in a dotted or linear pattern in the hydrophobic layer.

[0010] Preferably, the thickness of the material at the liquid absorption channel is lower than the thickness of the material itself, that is, the liquid absorption channel is recessed downward on the surface of the hydrophobic layer. Further, the thickness of the material at the liquid absorption channel is 60% to 90% of the thickness of the material itself.

[0011] Purpose: The downward indentation of the liquid absorption channel is to ensure that there is still some moisture between the material and the fresh meat, so as not to absorb the moisture on the surface of the fresh meat and to maintain the taste of the fresh meat.

[0012] Preferably, a layer of PP spunbond fabric is attached to the surface of the hydrophobic layer, and the areal density of the PP spunbond fabric is 8-15 g / m2.

[0013] Objective: PP spunbond fabric is a type of long-filament nonwoven fabric. PP material adheres less to fresh meat, and because it is long-filament, the probability of fiber shedding during the adhesion process is also lower.

[0014] Preferably, the double-layer slow-absorbing spunlace material is finished by single-sided calendering, with the hydrophobic layer side being the smooth side.

[0015] Purpose: Calendering is to reduce adhesion, because calendering reduces thickness. Single-sided calendering is used to reduce thickness as much as possible.

[0016] On the other hand, the present invention also provides a method for preparing a double-layer slow-absorbing hydroentangled material, comprising the following steps: (1) Preparation of hydrophilic layer fiber web: Plant pulp is made into slurry, and / or regenerated cellulose fiber is made into slurry, and the mixture is then processed into hydrophilic layer fiber web by a slant mesh forming system; (2) Preparation of hydrophobic fiber web: The hydrophobic fibers are opened, mixed and combed to form a hydrophobic fiber web; (3) Overlapping and hydroentanglement of fiber webs: The hydrophilic fiber web and the hydrophobic fiber web are overlapped and hydroentanglement is performed sequentially; wherein, the last hydroentanglement of the hydrophilic surface is dot-shaped or strip-shaped to form the liquid absorption channel; (4) Dehydration and drying: The hydroentangled fiber web is dehydrated and dried to obtain the double-layer slow-absorbing hydroentangled material.

[0017] Preferably, after drying in step (4), the material is further subjected to a single-sided calendering process to form a smooth surface on the side where the hydrophobic layer is located.

[0018] Preferably, in step (3), a layer of PP spunbond fabric is also laminated on the hydrophilic fiber web and / or the hydrophobic fiber web.

[0019] The beneficial effects of this invention are as follows: 1. Low cost and high production efficiency: The one-step process of directly hydroentanglement and reinforcement after online lamination of hydrophilic and hydrophobic layers completely eliminates the additional processes and equipment required for offline lamination, such as coating, lamination and curing, which significantly reduces production costs and improves production efficiency.

[0020] 2. Safe and environmentally friendly: The entire preparation process does not require the use of any chemical adhesives, avoiding the risk of chemical migration, and the product is more in line with the strict safety standards for food contact materials.

[0021] 3. Unique structure and superior performance: The liquid absorption channels formed through a specific hydroentangling process create a controllable flow path from the hydrophobic layer to the hydrophilic layer. This structure can not only guide exudate in a timely manner and prevent local water accumulation, but also regulate the overall liquid absorption rate by controlling the channel area, shape, and depth of the depression, avoiding excessive and rapid absorption of moisture from the surface of food (especially fresh meat) and effectively maintaining the original taste of the food.

[0022] 4. Excellent user experience: The PP spunbond fabric covering the hydrophobic layer and the single-sided calendering treatment greatly reduce the adhesion of the material to wet foods (such as fresh meat), while reducing the risk of fiber shedding and improving the convenience and cleanliness of the pad.

[0023] 5. Adjustable overall performance: By adjusting the ratio of hydrophilic / hydrophobic layers, liquid absorption channel parameters (distribution, area, width, indentation), and areal density, the liquid absorption rate, water retention rate, air permeability, and mechanical strength of the material can be flexibly adjusted to meet the specific needs of different application scenarios. Attached Figure Description

[0024] Figure 1 This is a schematic diagram showing that the liquid absorption channels are linearly distributed in the hydrophobic layer in an embodiment of the present invention.

[0025] Figure 2 This is a schematic diagram showing that the liquid absorption channels are distributed in a dotted pattern in the hydrophobic layer in an embodiment of the present invention.

[0026] Figure 3 This is a schematic diagram of the liquid absorption channel having a downwardly recessed structure on the surface of the hydrophobic layer in an embodiment of the present invention.

[0027] Figure 4 This is a schematic diagram of the material structure of PP spunbond fabric attached to the surface of the hydrophobic layer in an embodiment of the present invention.

[0028] Figure labeling: 1. Hydrophobic layer; 2. Hydrophilic layer; 3. Liquid absorption channel; 4. Recessed portion; 5. PP spunbond fabric. Detailed Implementation

[0029] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of the present invention.

[0030] General Implementation Examples A double-layer slow-absorbing spunlace material, such as Figure 1 As shown, the hydrophobic layer 1 is composed of hydrophobic fibers, which are one or more of the following: polyester, polypropylene, PE / PET fiber, PE / PP fiber, hydrophobically treated lyocell or viscose fiber; the hydrophilic layer 2 is composed of one or two of the following: plant pulp and regenerated cellulose short fibers; and includes liquid absorption channels 3 penetrating the hydrophobic layer 1 and the hydrophilic layer 2.

[0031] In one specific embodiment, the hydrophilic layer accounts for 50% to 70% of the total mass of the material, and the hydrophobic layer accounts for 30% to 50% of the total mass of the material; the liquid absorption channels can be dotted on the surface of the hydrophobic layer. Figure 2 ) or linear ( Figure 1 The hydrophobic layer is distributed in a manner that the liquid absorption channel area accounts for 5% to 20% of the hydrophobic layer surface area, and the width of each liquid absorption channel (single channel) is 2 to 8 mm. The material thickness at the liquid absorption channel is lower than that of the surrounding material, being 60% to 90% of the average material thickness, forming a recessed portion 4. Figure 3 ).

[0032] In one specific embodiment, a layer of PP spunbond fabric 5 is attached to the surface of the hydrophobic layer, and the areal density of the PP spunbond fabric 5 is 8-15 g / m².

[0033] In one specific implementation, the double-layer slow-absorbing spunlace material is subjected to single-sided calendering, wherein the hydrophobic layer side is the smooth side.

[0034] A method for preparing a double-layer slow-absorbing hydroentangled material includes the following steps: 1) Preparation of hydrophilic fiber web ① Preparation of plant pulp slurry: Plant pulp is fed into a hydrapulper and stirred by the pulper to produce a 0.1-2 wt% slurry; ② Preparation of regenerated cellulose fiber slurry: The regenerated fibers are added to water and stirred to disperse the fibers, thus preparing a fiber mixed slurry with a concentration of 0.1-1.5 wt%; ③ Fiber web forming: Plant pulp slurry, regenerated cellulose fiber slurry and broken fiber slurry are mixed in proportion to make a mixed slurry. After thickening, the concentration of the mixed slurry is controlled at 0.5-1.5 wt%. After screening to remove cotton lumps and cotton knots, it is sent to the inclined web forming system. After being formed by the inclined web, a hydrophilic fiber web is made. 2) Preparation of hydrophobic fiber web ① Fiber mixing: The required fibers are fed into the feeding device in proportion and mixed through coarse opening; ② Fiber web forming: The loosened and mixed fibers are fed into a carding machine for carding, and a hydrophobic fiber web is output.

[0035] 3) Lamination and Hydroentangling Reinforcement of Fiber Webs: The hydrophilic fiber web and the hydrophobic fiber web are laminated, resulting in a fiber web with hydrophilic and hydrophobic surfaces. During hydroentangling reinforcement, the hydrophilic surface is first hydroentangled at a pressure of 30–50 bar with 1–2 hydroentanglements; then the hydrophobic surface is hydroentangled at a pressure of 50–90 bar with 2–3 hydroentanglements; finally, the hydrophilic surface is hydroentangled again at a pressure of 50–90 bar with 1–2 hydroentanglements. In this final hydroentangling process, the hydronephrite needles do not perform full hydroentangling on the hydrophilic surface, but rather perform point-like or strip-like hydroentangling to form liquid absorption channels. A layer of PP spunbond fabric may also be laminated onto the hydrophilic fiber web and / or the hydrophobic fiber web, as needed.

[0036] 4) Dehydration and drying: The fiber layer reinforced by hydroentanglement is then dehydrated by vacuum suction and sent to the drying system for drying to form a double-layer slow-absorbing hydroentangled material.

[0037] 5) The dried fiber web can be calendered on one side to make the hydrophobic surface smoother.

[0038] Example 1 A double-layer slow-absorbing spunlace material, wherein the hydrophilic layer is composed of 60% hardwood pulp and 40% viscose fiber (8mm in length), accounting for 60% of the total mass of the material; the hydrophobic layer is composed of 100% polyester fiber, accounting for 40% of the total mass of the material; the liquid absorption channels are linearly distributed in the hydrophobic layer, with the area of ​​the liquid absorption channels accounting for 10% of the surface area of ​​the hydrophobic layer and a width of 5mm; the material thickness at the liquid absorption channels is 80% of the material's own thickness; a layer of PP spunbond fabric with an areal density of 10g / m² is attached to the surface of the hydrophobic layer. The material undergoes single-sided calendering, and the hydrophobic layer has a smooth surface. The unit area mass of the double-layer slow-absorbing hydroentangled material is 80 g / m².

[0039] A method for preparing a double-layer slow-absorbing hydroentangled material includes the following steps: (1) Preparation of hydrophilic layer fiber web: The hardwood pulp and viscose fiber were prepared into 0.8wt% and 1.0wt% pulps respectively, and after mixing, they were formed into a hydrophilic layer fiber web by oblique mesh forming, with a unit area mass of 48g / m². (2) Preparation of hydrophobic fiber web: 100% polyester fiber is coarsely opened and combed to make a hydrophobic fiber web with a unit area mass of 32g / m². (3) Fiber mesh stacking and hydroentanglement reinforcement: The hydrophilic layer and the hydrophobic layer are stacked, the hydrophilic surface is first hydroentangled (pressure 40 bar, 2 passes), the hydrophobic surface is then hydroentangled (pressure 70 bar, 2 passes), and finally the hydrophilic surface is hydroentangled in strips (pressure 80 bar, 1 pass) to form liquid absorption channels. (4) After dehydration and drying, perform single-sided calendering; (5) Finally, a double-layer slow-absorbing hydroentangled material was produced.

[0040] Example 2 A double-layer slow-absorbing spunlace material differs from Example 1 only in that: the liquid absorption channels are distributed in a dotted pattern in the hydrophobic layer, the area of ​​the liquid absorption channels accounts for 15% of the surface area of ​​the hydrophobic layer, and the width is 3mm; the material thickness at the liquid absorption channels is 70% of the material's own thickness; the mass of the hydrophilic layer accounts for 70% of the total mass of the material, and the mass of the hydrophobic layer accounts for 30% of the total mass of the material; the mass per unit area of ​​the material is 60g / m².

[0041] Example 3 A double-layer slow-absorbing spunlace material differs from Example 1 only in that: the hydrophilic layer is composed of 100% softwood pulp; the hydrophobic layer is composed of 50% polyester and 50% polypropylene; the material thickness at the liquid absorption channel is 90% of the material's own thickness; and the material's unit area mass is 100 g / m².

[0042] Comparative Example 1 A double-layer slow-absorbing spunlace material differs from Example 1 only in that it does not have a liquid absorption channel.

[0043] Comparative Example 2 A double-layer slow-absorbing spunlace material differs from Example 1 only in that the material has a single-layer hydrophilic structure, is composed of 100% hardwood pulp, and has a unit area mass of 80g / m².

[0044] Comparative Example 3 A double-layer slow-absorbing spunlace material differs from Example 1 only in that the material has a unit area mass of 130 g / m² and a liquid absorption channel width of 1 mm (too narrow).

[0045] Test data comparison and analysis Test objective: To test Example 1, Example 2, Example 3, Comparative Example 1, Comparative Example 2, and Comparative Example 3 respectively, and to test the unit area mass, thickness, tensile strength, liquid absorption rate, water retention rate, air permeability, and other indicators of the materials respectively, and to conduct comparative analysis.

[0046] Test method: (1) Mass per unit area: Tested in accordance with GB / T 24218.1 "Textiles - Test methods - Part 1: Determination of mass per unit area"; (2) Thickness: Tested in accordance with GB / T 24218.2 "Textiles - Test methods - Part 2: Determination of thickness"; (3) Breaking strength: Tested in accordance with GB / T 24218.3 "Textiles - Test methods for nonwoven fabrics - Part 3: Determination of breaking strength and elongation at break (strip method)"; (4) Absorption rate: Refer to GB / T 24218.6 "Textiles - Test methods - Part 6: Determination of absorbency" and record the time (seconds) required for the material to absorb 0.1 mL of water droplets. (5) Water retention rate: Refer to GB / T24218.6 to test the water retention rate (%) of the material after centrifugation after saturation water absorption; (6) Air permeability: Tested in accordance with GB / T 24218.15 "Textiles - Nonwovens - Test Methods - Part 15: Determination of air permeability".

[0047] Test results analysis: Examples 1-3 all exhibited moderate liquid aspiration rates (3.5-4.2 seconds), significantly faster than Comparative Example 1 without channels (6.8 seconds), and much slower than Comparative Example 2 with a single layer of hydrophilic material (2.1 seconds). This proves that the liquid aspiration channel design of the present invention achieves an effective "slow aspiration" function, which can guide the flow in a timely manner while avoiding excessively rapid liquid aspiration.

[0048] 1. Compared with Example 1, Example 2 uses point-like liquid absorption channels with lower surface density, resulting in a slightly slower liquid absorption rate and a slightly lower water retention rate, but better air permeability, making it suitable for scenarios where water seepage is slow. 2. Compared with Example 1, Example 3 has a higher areal density, increased thickness, improved tensile strength, and good liquid absorption performance, but decreased air permeability, making it suitable for scenarios requiring stronger support. 3. Compared with Example 1, Example 1 does not have a liquid suction channel, which significantly slows down the liquid suction rate, making it difficult to guide the flow in a timely manner and easily causing local water accumulation; 4. Compared with Example 1, Comparative Example 2 has a single-layer hydrophilic structure, which has an excessively fast liquid absorption rate and excessively high water retention rate, which can easily lead to excessive absorption of moisture from the surface of food and affect the taste. 5. Compared with Example 1, Comparative Example 3 has excessively high surface density, too narrow liquid absorption channels, poor air permeability, slow liquid absorption rate, and poor overall performance.

[0049] Unless otherwise specified, the raw materials and equipment used in this invention are all commonly used in the field; unless otherwise specified, the methods used in this invention are all conventional methods in the field.

[0050] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Any simple modifications, alterations, and equivalent transformations made to the above embodiments based on the technical essence of the present invention shall still fall within the protection scope of the present invention.

Claims

1. A double-layer slow-absorbing spunlace material, characterized in that: The material has an areal density of 50 g / m² to 120 g / m², and is composed of a hydrophilic layer and a hydrophobic layer, with liquid absorption channels existing between the hydrophilic layer and the hydrophobic layer; the mass of the hydrophilic layer accounts for 50% to 70% of the total mass of the material, and the mass of the hydrophobic layer accounts for 30% to 50% of the total mass of the material; on the hydrophobic layer, the area of ​​the liquid absorption channel accounts for 5% to 20% of the surface area of ​​the hydrophobic layer, and the width of the liquid absorption channel is 2 mm to 8 mm; the liquid absorption channel contains hydrophobic layer material and hydrophilic layer material, and the mass ratio of hydrophilic fibers to hydrophobic fibers therein is 1:5 to 1:

3.

2. The double-layer slow-absorbing spunlace material according to claim 1, characterized in that: The liquid absorption channels are distributed in a dotted or linear pattern on the surface of the hydrophobic layer.

3. The double-layer slow-absorbing spunlace material according to claim 1 or 2, characterized in that: The material thickness at the liquid absorption channel is lower than the thickness of the material itself, that is, the liquid absorption channel is recessed downward on the surface of the hydrophobic layer, and the material thickness at the liquid absorption channel is 60% to 90% of the thickness of the material itself.

4. The double-layer slow-absorbing spunlace material according to claim 1, characterized in that: The hydrophobic layer is composed of hydrophobic fibers, which are one or more of polyester, polypropylene, PE / PET fiber, PE / PP fiber, hydrophobically treated lyocell fiber or viscose fiber.

5. The double-layer slow-absorbing spunlace material according to claim 1, characterized in that: The hydrophilic layer material is one or a combination of two fibers selected from plant pulp and regenerated cellulose short fibers; the plant pulp includes one or more of hardwood pulp, softwood pulp, cotton pulp, hemp pulp, and bamboo pulp; the regenerated cellulose short fibers are one or more of viscose fiber, lyocell fiber, and modal fiber, with a length of 3mm to 15mm.

6. The double-layer slow-absorbing spunlace material according to claim 1, characterized in that: A layer of PP spunbond fabric is attached to the surface of the hydrophobic layer, and the areal density of the PP spunbond fabric is 8 g / m² to 15 g / m².

7. The double-layer slow-absorbing spunlace material according to claim 1, characterized in that: The material is finished by single-sided calendering, and the side containing the hydrophobic layer is smooth.

8. A method for preparing a double-layered slow-absorbing hydroentangled material as described in any one of claims 1 to 7, characterized in that, Includes the following steps: (1) Preparation of hydrophilic layer fiber web: Plant pulp is made into slurry, and / or regenerated cellulose fiber is made into slurry, and the mixture is then processed into hydrophilic layer fiber web by a slant mesh forming system; (2) Preparation of hydrophobic fiber web: The hydrophobic fibers are opened, mixed and combed to form a hydrophobic fiber web; (3) Overlapping and hydroentanglement of fiber webs: The hydrophilic fiber web and the hydrophobic fiber web are overlapped and hydroentanglement is performed sequentially; wherein, the last hydroentanglement of the hydrophilic surface is dot-shaped or strip-shaped to form the liquid absorption channel; (4) Dehydration and drying: The hydroentangled fiber web is dehydrated and dried to obtain the double-layer slow-absorbing hydroentangled material.

9. The method for using a double-layer slow-absorbing hydroentangled material according to claim 8, characterized in that, After drying in step (4), the material is further subjected to a single-sided calendering process to make the side containing the hydrophobic layer smooth.

10. The method for using a double-layer slow-absorbing hydroentangled material according to claim 8, characterized in that, In step (3), a layer of PP spunbond fabric is also laminated on the hydrophilic fiber web and / or the hydrophobic fiber web.

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