Viscose fiber absorbent core and method for manufacturing the same

Abstract

The application discloses a viscose fiber absorbent core and a preparation method thereof, and relates to the field of sanitary materials. The viscose fiber absorbent core comprises a first water-jet viscose fiber layer, a first adhesive layer, a first flexible layer, an absorbent core layer, a second flexible layer, a second adhesive layer and a second water-jet viscose fiber layer arranged in sequence; the first water-jet viscose fiber layer and the second water-jet viscose fiber layer are prepared from viscose fibers through a water-jet process; the first flexible layer and the second flexible layer are both viscose fiber layers without water-jet, and the viscose fiber layers without water-jet are obtained after viscose fibers are opened and carded into a viscose fiber net. The viscose fiber absorbent core has the advantages of good softness, fast diffusion and absorption speed, good air permeability, good anti-back seepage and stable structure, and is beneficial to improving the use comfort of users.

Description

Technical Field

[0001] This application relates to the field of sanitary materials, and in particular to a viscose fiber absorbent core and its preparation method. Background Technology

[0002] In the fields of hygiene products and medical care products, the absorbent core is a core functional component, and its performance directly affects the user experience and environmental characteristics of the product. Traditional absorbent cores typically use non-woven fabric layers made of synthetic fibers such as polyester or polypropylene through meltblown technology on both the upper and lower surfaces to achieve liquid conduction and structural support. However, these synthetic fiber materials have significant drawbacks: firstly, they are not very soft and tend to feel rough when in contact with the human body, reducing user comfort; secondly, materials such as polyester and polypropylene have limited hydrophilicity and liquid diffusion and permeability, causing liquid to easily accumulate on the core surface, leading to backflow problems and poor user comfort. Summary of the Invention

[0003] In order to improve the poor user comfort of absorbent cores in related technologies, this application provides a viscose fiber absorbent core and its preparation method.

[0004] Firstly, the viscose fiber absorbent core provided in this application adopts the following technical solution:

[0005] A viscose fiber absorbent core includes a first spunlace viscose fiber layer, a first adhesive layer, a first flexible layer, an absorbent core layer, a second flexible layer, a second adhesive layer, and a second spunlace viscose fiber layer arranged sequentially.

[0006] The first and second spunlace viscose fiber layers are made of viscose fibers through a hydroentangling process.

[0007] Both the first flexible layer and the second flexible layer are non-hydroentangled viscose fiber layers, and the non-hydroentangled viscose fiber layers are obtained by opening and carding viscose fibers into a viscose fiber web.

[0008] Traditional absorbent cores typically have two nonwoven fabric layers made of materials such as polyester or polypropylene through a melt-blown process on their upper and lower surfaces. This application uses a spunlace viscose fiber layer to replace the traditional polyester or polypropylene nonwoven fabric layer. Compared with the traditional polyester or polypropylene nonwoven fabric layer, the spunlace viscose fiber layer of this application (i.e., the first spunlace viscose fiber layer and the second spunlace viscose fiber layer) has better softness, rapid diffusion and permeability, and breathability. It is also biodegradable, which helps to improve user comfort and reduce backflow problems.

[0009] Secondly, the absorbent core of this application also includes a first flexible layer and a second flexible layer. The first flexible layer and the second flexible layer are viscose fiber layers obtained by opening and combing viscose fibers. The viscose fiber layers have better fluffiness and softness, and can also facilitate the stable adhesion of the absorbent core layer. There is no need to add an adhesive layer between the first flexible layer or the second flexible layer and the absorbent core layer. It can also promote the rapid diffusion and absorption of liquid, which is conducive to further improving comfort.

[0010] In addition, in order to improve the structural stability between the first spunlace adhesive fiber layer and the first flexible layer, and between the second spunlace adhesive fiber layer and the second flexible layer, this application adds a first adhesive layer between the first spunlace adhesive fiber layer and the first flexible layer, and adds a second adhesive layer between the second spunlace adhesive fiber layer and the second flexible layer.

[0011] In summary, the viscose fiber absorbent core of this application has the advantages of good softness, fast diffusion absorption speed, good air permeability, good anti-backflow properties, and structural stability, which are conducive to improving the user's comfort.

[0012] In some specific embodiments, the viscose fiber is an aminosilane coupling agent modified viscose fiber, and the first adhesive layer and the second adhesive layer are made of a styrene block copolymer, a tackifier, a plasticizer, silane coupling agent modified talc, and a peroxide initiator in a weight ratio of (35-45):(25-35):(15-25):(7.4-8.3):(0.1-0.2).

[0013] The silane coupling agent modified talc powder is obtained by modifying talc powder with both alkenyl silane coupling agent and epoxy silane coupling agent.

[0014] In this application, the viscose fibers used to prepare the first / second spunlace viscose fiber layers and the first / second flexible layers are preferably viscose fibers modified with an aminosilane coupling agent. Appropriate amounts of silane coupling agent-modified talc powder, obtained by modifying talc powder with both alkenyl silane coupling agents and epoxy silane coupling agents, are added to the first and second adhesive layers respectively. This allows the alkenyl groups on the silane coupling agent-modified talc powder to react with the double bonds in the hot melt adhesive powder, thereby improving the dispersibility and bonding stability of the silane coupling agent-modified talc powder in the hot melt adhesive powder. Simultaneously, the epoxy groups on the silane coupling agent-modified talc powder react and bond with the amino groups in the first / second spunlace viscose fiber layers and the first / second flexible layers, further enhancing the stability between the first spunlace viscose fiber layer and the first flexible layer, as well as between the second spunlace viscose fiber layer and the second flexible layer. Furthermore, in this application, the thickness of the first and second adhesive layers can be as low as 1-2 μm, which can improve the structural stability of the absorbent core while maintaining its air permeability.

[0015] In some specific embodiments, the aminosilane coupling agent modified viscose fiber is prepared by mixing aminosilane coupling agent and viscose fiber in a weight ratio of (0.1-0.2):5, and the weight ratio of alkenylsilane coupling agent, epoxysilane coupling agent and talc in the silane coupling agent modified talc powder is (0.15-0.2):(0.3-0.4):10.

[0016] In this application, controlling the weight ratio of aminosilane coupling agent to viscose fiber, as well as the weight ratio of alkenylsilane coupling agent, epoxysilane coupling agent, and talc powder within the above-mentioned range, is beneficial to further improve the structural stability of the absorbent core while also taking into account air permeability.

[0017] In some specific embodiments, the alkenylsilane coupling agent is at least one of vinyltrimethoxysilane, vinyltri(2-methoxyethoxy)silane, and vinyltriethoxysilane.

[0018] In some specific embodiments, the absorbent core layer comprises wood pulp fibers and superabsorbent polymer particles.

[0019] In this application, the absorbent core layer comprises wood pulp fibers and superabsorbent polymer (SAP) particles. The wood pulp fibers have a porous network structure, enabling them to rapidly absorb liquid through capillary action and quickly disperse it throughout the core area. This prevents localized liquid accumulation and leakage, improving dryness and reducing stuffiness. The SAP particles can absorb tens or even hundreds of times their own weight in liquid, locking it firmly within their network molecular structure to form a hydrogel. This effectively stores and shrinks the liquid, preventing backflow and seepage even under pressure, ensuring a dry skin contact surface.

[0020] In some specific embodiments, the thickness of the absorbent core layer is 1.8-2.5 mm, wherein the mass percentage of wood pulp fiber is 35-45%, and the mass percentage of the superabsorbent polymer particles is 55-65%.

[0021] In some specific embodiments, the first spunlace viscose fiber layer and the second spunlace viscose fiber layer are obtained by sequentially opening the viscose fibers, combing them into a viscose fiber web, laying the viscose fiber web at 90° cross-laying, stretching, spunlace, and drying. In the spunlace step, spunlace pressures of 20-30 bar, 40-50 bar, and 80-100 bar are used sequentially.

[0022] In this application, the first / second spunlace viscose fiber web layers adopt a 90° cross-layout, which breaks the unidirectional arrangement of fibers and makes the web structure isotropic, which is beneficial to improve dimensional stability. The multidirectional fiber network can accelerate liquid diffusion. The spunlace pressure is divided into three gradients: 20-30 bar is beneficial to initially fix the fiber position to prevent displacement caused by direct high pressure impact; 40-50 bar is beneficial to form the main web skeleton and improve the basic strength; and 80-100 bar is beneficial to achieve permanent entanglement between fibers, which can improve the structural stability of the first / second spunlace viscose fiber web layers.

[0023] In some specific embodiments, the areal density of the viscose fiber web is 35-45 g / m². 2 When the viscose fiber web is laid in a 90° cross pattern, the number of viscose fiber web sheets is 6-8.

[0024] In some specific implementations, the stretching ratio in the stretching step is 2-2.5 times.

[0025] Secondly, the method for preparing a viscose fiber absorbent core provided in this application adopts the following technical solution:

[0026] A method for preparing a viscose fiber absorbent core includes the following steps:

[0027] A first adhesive layer is rolled onto the surface of a first spunlace viscose fiber layer, and then a first flexible layer is placed over the surface of the first adhesive layer. Next, an absorbent core layer is formed on the surface of the first flexible layer, and a second flexible layer is placed over the surface of the absorbent core layer to obtain a pre-formed core. A second adhesive layer is rolled onto the surface of a second spunlace viscose fiber layer, and then the second adhesive layer is placed over the surface of the second flexible layer of the pre-formed core and pressed together to obtain a viscose fiber absorbent core.

[0028] In summary, this application includes at least the following beneficial technical effects:

[0029] (1) This application uses a spunlace viscose fiber layer to replace the traditional polyester or polypropylene nonwoven fabric layer. Compared with the traditional polyester or polypropylene nonwoven fabric layer, the spunlace viscose fiber layer (i.e., the first spunlace viscose fiber layer and the second spunlace viscose fiber layer) of this application has better softness, rapid diffusion and permeability, and breathability. It is also biodegradable, which helps to improve user comfort and reduce backflow problems. Secondly, the absorbent core of this application also adds a first flexible layer and a second flexible layer. The first flexible layer and the second flexible layer are viscose fiber layers obtained by opening and combing viscose fibers. The viscose fiber layer has better fluffiness and softness, and it can also help the absorbent core layer to adhere stably. There is no need to add an adhesive layer between the first flexible layer or the second flexible layer and the absorbent core layer. It can also promote the rapid diffusion and absorption of liquid, which helps to further improve comfort. In addition, in order to improve the structural stability between the first spunlace adhesive fiber layer and the first flexible layer, and between the second spunlace adhesive fiber layer and the second flexible layer, this application adds a first adhesive layer between the first spunlace adhesive fiber layer and the first flexible layer, and adds a second adhesive layer between the second spunlace adhesive fiber layer and the second flexible layer.

[0030] (2) In this application, the viscose fibers used to prepare the first / second spunlace viscose fiber layer and the first / second flexible layer are preferably viscose fibers modified with an aminosilane coupling agent. The first adhesive layer and the second adhesive layer are respectively added with an appropriate amount of silane coupling agent modified talc obtained by modifying talc with alkenyl silane coupling agent and epoxy silane coupling agent. The alkenyl groups on the silane coupling agent modified talc can react with the double bonds in the hot melt adhesive powder, thereby improving the dispersibility and bonding stability of the silane coupling agent modified talc in the hot melt adhesive powder. At the same time, the epoxy groups on the silane coupling agent modified talc react and bond with the amino groups in the first / second spunlace viscose fiber layer and the first / second flexible layer, which is beneficial to further improve the stability between the first spunlace viscose fiber layer and the first flexible layer, as well as between the second spunlace viscose fiber layer and the second flexible layer. Meanwhile, in this application, the thickness of the first adhesive layer and the second adhesive layer can be as low as 1-2 μm, which can improve the structural stability of the absorbent core while taking into account the air permeability of the absorbent core. Attached Figure Description

[0031] Figure 1 This is a schematic diagram of the structure of the viscose fiber absorbent core of this application.

[0032] Explanation of reference numerals in the attached figures:

[0033] 1. First spunlace viscose fiber layer; 2. First adhesive layer; 3. First flexible layer; 4. Absorbent core layer; 5. Second flexible layer; 6. Second adhesive layer; 7. Second spunlace viscose fiber layer. Detailed Implementation

[0034] The following section provides further explanation of this application in conjunction with specific experiments.

[0035] Preparation Example

[0036]

Preparation Example 1-1

[0037] The preparation method of the spunlace viscose fiber layer is as follows:

[0038] Step 1: Open and card the viscose fiber (Fuhui, dry breaking strength 2.15 CN / dtex) sequentially to a surface density of 40 g / m². 2 viscose fiber web;

[0039] Step 2: Lay 7 viscose fiber webs in a 90° cross pattern. After laying the webs, stretch them to twice their original length. Then, spun them into a hydroentangled layer and dry them to obtain a hydroentangled viscose fiber layer. In the hydroentanglement step, hydroentanglement pressures of 25 bar, 450 bar, and 88 bar are used in sequence.

[0040]

Preparation Examples 1-2

[0041] The preparation method of the spunlace viscose fiber layer differs from that in [Preparation Example 1-1] in that: in step 1, the viscose fiber is replaced by viscose fiber modified with an aminosilane coupling agent. The preparation method of the aminosilane coupling agent modified viscose fiber is as follows:

[0042] 0.15 kg of silane coupling agent KH550 was added to 100 kg of 95% ethanol aqueous solution. After stirring and dissolving evenly, 5 kg of viscose fiber was added, and the mixture was heated to 45-50℃ to react. Then, the mixture was filtered, washed, and dried to obtain aminosilane coupling agent modified viscose fiber.

[0043]

Preparation Example 2-1

[0044] The flexible layer is the viscose fiber web obtained in step 1 of [Preparation Example 1-1].

[0045]

Preparation Example 2-2

[0046] The flexible layer is the viscose fiber web obtained in step 1 of [Preparation Examples 1-2].

[0047]

Preparation Example 3-1

[0048] A hot melt adhesive granule is obtained by melt extrusion, granulation, and cooling of styrene-isoprene-styrene copolymer (Baling Petrochemical grade 1105), C5 / C9 copolymer petroleum resin (Exxon 5690), naphthenic oil (4010 naphthenic oil), talc modified with silane coupling agent, and dicumyl peroxide in a weight ratio of 40:30:20:8:0.1 at 170-180℃.

[0049] The preparation method of silane coupling agent modified talc is as follows:

[0050] 0.165 kg of vinyltriethoxysilane and 0.35 kg of epoxysilane coupling agent KH560 were added to 100 kg of 95% ethanol aqueous solution. After stirring and dissolving evenly, 10 kg of talc powder was added, and the mixture was heated to 55-60℃ to react. Then, the mixture was filtered, washed, and dried to obtain silane coupling agent modified talc powder.

[0051]

Preparation Example 3-2

[0052] A type of hot melt adhesive granule differs from that in [Preparation Example 3-1] in that the silane coupling agent modified talc powder is different. In this preparation example, the preparation method of the silane coupling agent modified talc powder is as follows:

[0053] 0.515 kg of epoxy silane coupling agent KH560 was added to 100 kg of 95% ethanol aqueous solution. After stirring and dissolving evenly, 10 kg of talc powder was added, and the mixture was heated to 55-60℃ for reaction. Then, the mixture was filtered, washed, and dried to obtain silane coupling agent modified talc powder.

[0054]

Preparation Example 3-3

[0055] A type of hot melt adhesive granule differs from that in [Preparation Example 3-1] in that the silane coupling agent modified talc powder is different. In this preparation example, the preparation method of the silane coupling agent modified talc powder is as follows:

[0056] 0.515 kg of vinyltriethoxysilane was added to 100 kg of 95% ethanol aqueous solution and stirred until dissolved. Then, 10 kg of talc powder was added and the mixture was heated to 55-60℃ to react. The mixture was then filtered, washed, and dried to obtain silane coupling agent modified talc powder.

[0057] Example

[0058]

Example 1

[0059] A viscose fiber absorbent core, as described above Figure 1 It includes a first spunlace viscose fiber layer, a first adhesive layer, a first flexible layer, an absorbent core layer, a second flexible layer, a second adhesive layer, and a second spunlace viscose fiber layer arranged sequentially.

[0060] The first and second spunlace viscose fiber layers are both made using the spunlace viscose fiber layers prepared in [Preparation Example 1-1]; the first and second flexible layers are both made using the flexible layers in [Preparation Example 2-1]; the first and second adhesive layers are both made using the hot melt adhesive particles in [Preparation Example 3-1]; the absorbent core layer includes wood pulp fiber and SAP superabsorbent polymer particles (Mingqi Chemical), with wood pulp fiber accounting for 40% by weight and SAP superabsorbent polymer particles accounting for 60% by weight.

[0061] In this embodiment, the viscose fiber absorbent core is prepared as follows:

[0062] Hot melt adhesive particles are rolled onto the surface of the first spunlace adhesive fiber layer to form the first adhesive layer, which has a thickness of 1 μm. Then, the first flexible layer is covered on the surface of the first adhesive layer. Next, wood pulp fiber and SAP superabsorbent polymer particles are sprayed onto the surface of the first flexible layer in sequence according to the ratio to form an absorbent core layer with a thickness of 1.8 mm. Finally, the second flexible layer is covered on the surface of the absorbent core layer to obtain the prefabricated core.

[0063] Hot melt adhesive particles are rolled onto the surface of the second spunlace viscose fiber layer to form a second adhesive layer with a thickness of 1 μm; then the second adhesive layer is covered on the surface of the second flexible layer of the preformed core and pressed together to obtain the viscose fiber absorbent core.

[0064]

Example 2

[0065] A viscose fiber absorbent core differs from [Example 1] in that: the first spunlace viscose fiber layer and the second spunlace viscose fiber layer are both made of spunlace viscose fiber layers prepared in [Preparation Examples 1-2]; the first flexible layer and the second flexible layer are both made of flexible layers in [Preparation Examples 2-2].

[0066]

Example 3

[0067] A viscose fiber absorbent core differs from [Example 2] in that both the first adhesive layer and the second adhesive layer are made from hot melt adhesive particles as described in [Preparation Example 3-2].

[0068]

Example 4

[0069] A viscose fiber absorbent core differs from [Example 2] in that both the first adhesive layer and the second adhesive layer are made from hot melt adhesive particles as described in [Preparation Example 3-3].

[0070]

Example 5

[0071] A viscose fiber absorbent core differs from [Example 1] in that the thickness of both the first adhesive layer and the second adhesive layer is 8 μm.

[0072] Comparative Example

[0073] Comparative Example 1

[0074] A viscose fiber absorbent core differs from [Example 1] in that the first flexible layer and the second flexible layer are omitted.

[0075] Performance testing

[0076] 1. Referring to QB / T 5650-2021 "Composite absorbent core for disposable paper sanitary products", the absorption rate and reabsorption volume of the core were tested. The test solutions were physiological saline and animal blood, and the volume of each test solution was 200 mL. The results are recorded in Table 1 below.

[0077] 2. Air permeability: The air permeability of the samples prepared in each embodiment and comparative example of this application was tested in accordance with GB / T 5453-1997, and the test results are recorded in Table 2 below.

[0078] 3. Structural stability: Take 200ml and 500mL of physiological saline (mass concentration 0.9%) and heat to 40℃ respectively. Then add the physiological saline to the core. Place the absorbent core sample in a test chamber at 40±1℃ and 65±1%RH for 10min. Then take out the absorbent core sample for testing. The tester holds both ends of the absorbent core sample with both hands. First, shake one end of the absorbent core sample with one hand and repeat 10 times. Then stretch both ends of the absorbent core sample back and forth with both hands and repeat 10 times. Then rub the core with both hands and repeat 10 times. Finally, observe whether the absorbent core shows clumping and record the results in Table 3.

[0079] Table 1

[0080] Table 2

[0081]

[0082] Table 3

[0083] Based on the test data in Example 1, Comparative Example 1, and Tables 1-3, it can be seen that when the first or second flexible layer of the absorbent core is omitted, the absorption rate of the absorbent core decreases. At the same time, the structural stability of the absorbent core also decreases. This is because the lack of the flexible layer's limiting and fixing effect on the wood pulp fiber and the superabsorbent polymer reduces the structural stability of the absorbent core.

[0084] Based on the test data in Examples 1 and 2-4 and Tables 1-3, it can be seen that the first / second spunlace viscose fiber layer and the first / second flexible layer are both prepared by modifying viscose fibers with aminosilane coupling agents. At the same time, when talc powder, a silane coupling agent obtained by co-modifying alkenyl silane coupling agent and epoxy silane coupling agent, is added to the first / second adhesive layer, the thickness of the first / second adhesive layer can be as low as 1μm, which ensures the structural stability of the absorbent core while also allowing the absorbent core to have good air permeability.

[0085] Based on the test data in Examples 1 and 5 and Tables 1-3, it can be seen that increasing the thickness of the first / second adhesive layer can improve the structural stability of the absorbent core and make it less prone to clumping. However, the absorption rate and air permeability of the absorbent core decrease.

[0086] This specific embodiment is merely an explanation of this application and is not intended to limit it. After reading this specification, those skilled in the art can make modifications to this specific embodiment without contributing any inventive step, but such modifications are protected by patent law as long as they fall within the scope of the claims of this application.

Claims

1. A viscose fiber absorbent core, characterized in that: The device comprises, in sequence, a first spunlace viscose fiber layer, a first adhesive layer, a first flexible layer, an absorbent core layer, a second flexible layer, a second adhesive layer, and a second spunlace viscose fiber layer; the first and second spunlace viscose fiber layers are made of viscose fibers through a hydroentangling process; both the first and second flexible layers are non-spunlace viscose fiber layers, and the non-spunlace viscose fiber layers are obtained by opening and carding viscose fibers into a viscose fiber web; The viscose fiber is modified with an aminosilane coupling agent. The first adhesive layer and the second adhesive layer are prepared from a styrene block copolymer, a tackifier, a plasticizer, silane coupling agent-modified talc, and a peroxidation initiator in a weight ratio of (35-45):(25-35):(15-25):(7.4-8.3):(0.1-0.2). The silane coupling agent-modified talc is obtained by modifying talc with an alkenyl silane coupling agent and an epoxy silane coupling agent. The aminosilane coupling agent modified viscose fiber is prepared by mixing aminosilane coupling agent and viscose fiber in a weight ratio of (0.1-0.2):

5. In the silane coupling agent modified talc powder, the weight ratio of alkenylsilane coupling agent, epoxysilane coupling agent and talc powder is (0.15-0.2):(0.3-0.4):

10. The thickness of the first adhesive layer and the second adhesive layer is 1-2 μm.

2. The viscose fiber absorbent core according to claim 1, characterized in that: The alkenylsilane coupling agent is at least one of vinyltrimethoxysilane, vinyltri(2-methoxyethoxy)silane, and vinyltriethoxysilane.

3. The viscose fiber absorbent core according to claim 1, characterized in that: The absorbent core layer comprises wood pulp fibers and superabsorbent polymer particles.

4. The viscose fiber absorbent core according to claim 1, characterized in that: The first and second spunlace viscose fiber layers are obtained by sequentially opening and combing the viscose fibers into a viscose fiber web, laying the viscose fiber web at 90° cross-laying, stretching, hydroentangling, and drying. In the hydroentangling step, hydroentangling pressures of 20-30 bar, 40-50 bar, and 80-100 bar are used sequentially.

5. The viscose fiber absorbent core according to claim 4, characterized in that: The areal density of the viscose fiber web is 35-45 g / m2; when the viscose fiber web is laid in a 90° cross-lay, the number of viscose fiber web sheets is 6-8.

6. The viscose fiber absorbent core according to claim 4, characterized in that: During the stretching step, the stretching ratio is 2-2.5 times.

7. A method for preparing a viscose fiber absorbent core as described in any one of claims 1-6, characterized in that: Includes the following steps: A first adhesive layer is rolled onto the surface of a first spunlace viscose fiber layer, and then a first flexible layer is placed over the surface of the first adhesive layer. Next, an absorbent core layer is formed on the surface of the first flexible layer, and a second flexible layer is placed over the surface of the absorbent core layer to obtain a pre-formed core. A second adhesive layer is rolled onto the surface of a second spunlace viscose fiber layer, and then the second adhesive layer is placed over the surface of the second flexible layer of the pre-formed core and pressed together to obtain a viscose fiber absorbent core.

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