Composite structure spunlace nonwoven fabric for paper diaper surface layer and preparation method thereof

Abstract

The application provides a composite structure spunlace non-woven fabric for a paper diaper surface layer and a preparation method thereof, comprising a first fiber web layer and a second fiber web layer that are spunlace entangled, the first fiber web layer comprises polyester fibers and first modified viscose fibers, the second fiber web layer comprises second modified viscose fibers and kapok fibers, a modifier of the first modified viscose fibers is alkyl silane coupling agent, and a modifier of the second modified viscose fibers is quaternary ammonium salt silane coupling agent; the amount of the alkyl silane coupling agent in the first modified viscose fibers is 10-20 wt% of the viscose fibers, and the amount of the quaternary ammonium salt silane coupling agent in the second modified viscose fibers is 1-5 wt% of the viscose fibers. The non-woven fabric prepared by using the first modified viscose fibers and the polyester fibers as the first fiber layer web and the second modified viscose fibers and the kapok fibers as the second fiber layer web is not prone to reverse seepage, is wettable but not water-absorbing, and can quickly allow water to pass through.

Description

Technical Field

[0001] This invention belongs to the field of nonwoven fabric technology, specifically relating to a composite structure spunlace nonwoven fabric for the surface layer of diapers and its preparation method. Background Technology

[0002] Since the beginning of the 21st century, my country has made significant progress in the production technology and application of disposable hygiene materials, with continuously growing consumer demand. A complete supply chain system has been formed, encompassing equipment manufacturing, raw material production, and product processing, with the production and application of nonwoven fabrics being particularly prominent. Nonwoven fabric products have a wide range of applications, including aerospace, agriculture, medical supplies, and daily necessities. In our daily lives, we encounter most frequently disposable hygiene materials made from nonwoven fabrics, such as diapers, sanitary napkins, and panty liners.

[0003] Nonwoven fabrics are mainly used in the top layer of absorbent products such as diapers, sanitary napkins, and panty liners. Their function is to act as a separator and filter, creating a clean barrier between the skin and the liquid reservoir. Simultaneously, when liquid is discharged, it allows the liquid to flow smoothly through this top layer into the reservoir. For example, patent CN201361291Y discloses a fully biodegradable diaper top layer material, which is formed by integrating upper and lower fiber webs. The upper web has larger pores, while the lower web has smaller pores, creating a tapered pore shape along its thickness, forming a gradient structure with larger pores at the top and smaller pores at the bottom. The upper web is a polylactic acid bicomponent fiber web, and the lower web is a kapok fiber web. The linear density of the polylactic acid bicomponent fibers in the upper web is 2.2–6.6 dtex, and the length is 38–65 mm. The length of the kapok fibers in the lower web is 16–30 mm, and the average linear density is 0.9–1.2 dtex. Patent CN113151977B discloses an ultra-soft, anti-reverse-leakage kapok diaper material and its preparation method. The material is composed of two fiber webs with different pore sizes. One layer is a kapok / viscose hydroentangled fiber web, and the other absorbent layer is a viscose / wood pulp wet-laid fiber web. The preparation method is as follows: ① A uniform kapok / viscose hydroentangled fiber web is initially prepared using a hydroentangling process; ② A viscose / wood pulp wet-laid fiber web is obtained by forming the web using a wet-laid process through an inclined wire; ③ The viscose / wood pulp wet-laid fiber web output from the inclined wire and the kapok / viscose hydroentangled fiber web output from the lower wire are then combined through a flat wire and a rotating drum hydroentangling process; ④ The composite fiber web is dried by a combination of drying cylinder and hot air, and after dehydration, the ultra-soft, anti-reverse-leakage kapok diaper material is obtained.

[0004] The aforementioned surface layer is soft, non-irritating, and permeable to human skin, forming an isolation barrier between the skin and the liquid storage layer. However, the fiber surface of this surface layer has a high hydroxyl content, making it prone to backflow, high moisture regain, and even some water absorption. This results in a long time for the liquid to seep into the liquid storage layer through the surface layer, and it can also generate a large amount of moisture backflow due to external forces.

[0005] Therefore, it is necessary to develop a nonwoven fabric that is not prone to backflow, is moist but not absorbent, and has good permeability, allowing liquid to pass smoothly through and transfer to the liquid storage layer. Summary of the Invention

[0006] To address the aforementioned technical problems, this invention provides a composite structure spunlace nonwoven fabric for diaper surface layers and its preparation method. Different dosages of silane coupling agents are used as modifiers to hydrophobically modify viscose fibers to varying degrees, reducing the number and density of hydroxyl groups on the viscose fiber surface to improve its absorbency. This yields a first modified hydrophobic viscose fiber and a second modified viscose fiber with reduced absorbency. The first modified viscose fiber is combined with polyester fiber to form a first fiber layer web, and the second modified viscose fiber is combined with kapok fiber to form a second fiber layer web. The nonwoven fabric obtained by combining the first and second fiber layer webs through a hydroentangling process is non-permeable, moisture-loving but not absorbent, and can quickly allow water to pass through, making it particularly suitable for diaper surface layers.

[0007] To achieve the above objectives, the present invention adopts the following technical solution:

[0008] A composite structure spunlace nonwoven fabric for the surface layer of a diaper includes a first spunlace entangled fiber web layer and a second fiber web layer. The first fiber web layer includes polyester fibers and a first modified viscose fiber, and the second fiber web layer includes a second modified viscose fiber and kapok fibers. The modifier for the first modified viscose fiber is an alkyl silane coupling agent, and the modifier for the second modified viscose fiber is a quaternary ammonium salt silane coupling agent. The amount of alkyl silane coupling agent in the first modified viscose fiber is 10-20 wt% of the viscose fiber, and the amount of quaternary ammonium salt silane coupling agent in the second modified viscose fiber is 1-5 wt% of the viscose fiber.

[0009] Preferably, the amount of alkylsilane coupling agent in the first modified viscose fiber is 10-15 wt% of the viscose fiber, and the amount of quaternary ammonium salt silane coupling agent in the second modified viscose fiber is 3-5 wt% of the viscose fiber.

[0010] Furthermore, the mass ratio of polyester fiber to first modified viscose fiber in the first fiber web layer is 100:15-20; the mass ratio of second modified viscose fiber to kapok fiber in the second fiber web layer is 50-70:30-50.

[0011] The alkylsilane coupling agent is selected from one or a combination of two or more of octyltrimethoxysilane, n-decyltrimethoxysilane, butyltrimethoxysilane, ethyltrimethoxysilane, methyltrimethoxysilane, and propyltrimethoxysilane.

[0012] The quaternary ammonium salt silane coupling agent is selected from one or a combination of two or more of dimethyloctadecyl[3-(trimethoxysilyl)propyl]ammonium chloride, 2-methacryloyloxyethyltrimethylammonium chloride, and 4-vinylbenzyldimethyl-(3-trimethoxysilyl)propyl)ammonium chloride.

[0013] The first modified viscose fiber is prepared by a method comprising the following steps:

[0014] An alcohol-water mixture is added to a reaction vessel to adjust the pH, and an alkylsilane coupling agent is added for hydrolysis to obtain a hydrolysate. The viscose fiber is then immersed in the hydrolysate, heated, and kept at a constant temperature for 1-3 hours, turning it over once every 15-20 minutes. The fiber is then filtered, washed, and dried. The amount of alkylsilane coupling agent used is 10-20 wt% of the viscose fiber, preferably 10-15 wt%.

[0015] The second modified viscose fiber is prepared by a method comprising the following steps:

[0016] The alcohol-water mixture is added to the reaction vessel to adjust the pH, and a quaternary ammonium salt silane coupling agent is added for hydrolysis to obtain a hydrolysate. The viscose fiber is immersed in the hydrolysate, heated and kept at a constant temperature for 1-3 hours, and turned over once every 15-20 minutes. The fiber is then filtered, washed, and dried. The amount of quaternary ammonium salt silane coupling agent used is 1-5 wt% of the viscose fiber, preferably 3-5 wt%.

[0017] The water concentration in the alcohol-water mixture is 80-95% by mass; the alcohol is selected from one or a combination of two of methanol and ethanol; the pH is adjusted to 4.5-5.5; the hydrolysis time is 3-10 min; the temperature is raised to 50-60℃; the reaction time after heating is 0.5-2 h; and the drying is carried out in an oven at 100-120℃ for 10-30 min.

[0018] The first modified viscose fiber is made by modifying viscose fiber with an excess of alkylsilane coupling agent. The excess alkylsilane coupling agent forms a strong silicone film on the surface of the viscose fiber, which facilitates the flow of liquid from the first fiber web layer to the second fiber web layer, making the nonwoven fabric feel comfortable.

[0019] The second modified viscose fiber is made by modifying viscose fiber with a small amount of quaternary ammonium salt silane coupling agent. The small amount of modifier is first hydrolyzed to generate silanol. The silanol reacts with the hydroxyl groups on the surface of the viscose fiber to obtain the second modified viscose fiber with surface-bonded silane coupling agent. In particular, the quaternary ammonium salt silane coupling agent has good hydrophilicity of quaternary ammonium salt cations, and at the same time has hydrophobic long carbon chain alkyl groups, which makes it easier to penetrate into water. This makes it difficult for small water droplets adsorbed on the fiber surface to merge into large water droplets, and makes the nonwoven fabric made from it less prone to moisture re-dampening when subjected to external force.

[0020] The areal density of the first and second fiber web layers is 15-30 g / m². 2 The areal density of the composite spunlace nonwoven fabric used for the surface layer of the diaper is 30-50 g / m². 2 .

[0021] The viscose fiber has a fineness of 1-1.5 dtex and a length of 30-40 mm; the kapok fiber has a fineness of 1-1.5 dtex and a length of 15-30 mm; and the polyester fiber has a fineness of 1-2 dtex and a length of 30-40 mm.

[0022] The cross-sectional shape of the polyester fiber is selected from one of the following: cross-shaped, circular, triangular, and I-shaped.

[0023] The present invention also provides a method for preparing the above-mentioned composite structure spunlace nonwoven fabric for the surface layer of diapers, comprising the following steps:

[0024] 4) The polyester fibers and the first modified viscose fibers are opened, mixed, and combed separately to form the first fiber web;

[0025] 5) The second modified viscose fiber and kapok fiber are opened, mixed, and combed separately to form a second fiber web;

[0026] 6) The first fiber web and the second fiber web are combined, reinforced by hydroentangling, dried and rolled to obtain the composite structure hydroentangled nonwoven fabric for the surface layer of diapers.

[0027] Step 3) The composite method is selected from one of cross-laying and parallel-laying, the hydroentangling pressure is 4-10MPa, and the number of hydroentangling channels is 3-7.

[0028] Compared with the prior art, the beneficial effects of the present invention are:

[0029] This invention utilizes different dosages of alkyl or quaternary ammonium silane coupling agents as modifiers to perform hydrophobic modification on viscose fibers to varying degrees, reducing the number and distribution density of hydroxyl groups on the surface of the viscose fibers to improve their water absorption. This results in a first modified hydrophobic viscose fiber and a second modified viscose fiber with reduced water absorption. The nonwoven fabric made by combining the first modified viscose fiber with polyester fiber as the first fiber layer web and the second modified viscose fiber with kapok fiber as the second fiber layer web is not prone to backflow, is moist but does not absorb water, and can quickly allow water to pass through. Detailed Implementation

[0030] The present invention will be further described below with reference to specific embodiments, but is not limited to the contents of the specification. Unless otherwise specified, all "parts" mentioned in the embodiments of the present invention are parts by weight. All reagents used are commercially available in the art.

[0031] The viscose fiber was purchased from Lenzing (Nanjing) Fiber Co., Ltd., with a fineness of 1.67 dtex and a length of 38 mm;

[0032] The polyester fiber was purchased from Sinopec; it is YZ310 polyester staple fiber with a fineness of 1.56 dtex and a length of 38 mm.

[0033] Kapok fiber was purchased from Shanghai Panzhihua Industrial (Group) Co., Ltd., with a fineness of 1.44 dtex and a length of 26 mm.

[0034] Preparation of the first modified viscose fiber

[0035] Preparation Example a1

[0036] Mix 90 parts water and 10 parts ethanol evenly, add acetic acid to adjust the pH to 5, add 5 parts octyltrimethoxysilane to hydrolyze for 5 minutes to obtain hydrolysate, immerse 33.5 parts viscose fiber in the hydrolysate, heat to 60℃ and react at a constant temperature for 3 hours, turn over once every 15 minutes, filter, wash with water 3 times, and dry in an oven at 120℃ for 10 minutes.

[0037] Preparation Example a2

[0038] The rest is the same as in preparation example a1, except that 50 parts of viscose fiber are immersed in the hydrolysate.

[0039] Comparative preparation example a1

[0040] The rest is the same as in Preparation Example a1, except that 5 parts of dimethyloctadecyl[3-(trimethoxysilyl)propyl]ammonium chloride are replaced with 5 parts of dimethyloctadecyl[3-(trimethoxysilyl)propyl]ammonium chloride.

[0041] Comparative preparation example a2

[0042] The rest is the same as in preparation example a1, except that 62.5 parts of viscose fiber were immersed in the hydrolysate.

[0043] Preparation of second modified viscose fiber

[0044] Preparation Example b1

[0045] Mix 90 parts water and 10 parts ethanol evenly, add acetic acid to adjust the pH to 5, add 5 parts dimethyloctadecyl[3-(trimethoxysilyl)propyl]ammonium chloride and hydrolyze for 5 min to obtain hydrolysate. Immerse 100 parts viscose fiber in the hydrolysate, heat to 60℃ and keep the temperature constant for 3 h, turn over once every 15 min, filter, wash with water 3 times, and dry in an oven at 120℃ for 10 min.

[0046] Preparation Example b2

[0047] Mix 90 parts water and 10 parts ethanol evenly, add acetic acid to adjust the pH to 5, add 3 parts dimethyloctadecyl[3-(trimethoxysilyl)propyl]ammonium chloride and hydrolyze for 5 min to obtain hydrolysate. Immerse 100 parts viscose fiber in the hydrolysate, heat to 60℃ and keep the temperature constant for 3 h, turn over once every 15 min, filter, wash with water 3 times, and dry in an oven at 120℃ for 10 min.

[0048] Comparative preparation example b1

[0049] The rest is the same as in preparation example b1, except that 5 parts of dimethyloctadecyl[3-(trimethoxysilyl)propyl]ammonium chloride are replaced with 5 parts of octyltrimethoxysilane.

[0050] Comparative preparation example b2

[0051] The rest is the same as in preparation example b1, except that 8 parts of dimethyloctadecyl[3-(trimethoxysilyl)propyl]ammonium chloride are added.

[0052] Composite structure spunlace nonwoven fabric for preparing the surface layer of diapers

[0053] Example 1

[0054] 1) 100 parts of polyester fiber and 20 parts of the first modified viscose fiber prepared in preparation example a1 are opened, mixed and combed to form a first fiber web;

[0055] 2) Open, mix, and comb 70 parts of the second modified viscose fiber prepared in preparation example b1 and 30 parts of kapok fiber respectively to form a second fiber web;

[0056] 3) The first and second fiber webs are cross-laid and reinforced with three hydroentangling processes. The pressure of the first hydroentangling process is 4.5 MPa, the pressure of the second hydroentangling process is 7.5 MPa, and the pressure of the third hydroentangling process is 4.5 MPa. Then, the web is dried and rolled up to obtain the composite structure hydroentangled nonwoven fabric for the surface layer of diapers.

[0057] Example 2

[0058] The rest is the same as in Example 1, except that in step 1), the first modified viscose fiber is prepared in preparation example a2.

[0059] Example 3

[0060] The rest is the same as in Example 1, except that in step 2), the second modified viscose fiber is prepared in preparation example b2.

[0061] Example 4

[0062] The rest is the same as in Example 1, except that in step 1), the amount of the first modified viscose fiber is 15 parts.

[0063] Example 5

[0064] The rest is the same as in Example 1, except that in step 2), the amount of the second modified viscose fiber is 50 parts and the amount of kapok fiber is 50 parts.

[0065] Comparative Example 1

[0066] The rest is the same as in Example 1, except that in step 1), the first modified viscose fiber was prepared in Comparative Preparation Example a1.

[0067] Comparative Example 2

[0068] The rest is the same as in Example 1, except that in step 2), the second modified viscose fiber is prepared as in Comparative Preparation Example b1.

[0069] Comparative Example 3

[0070] The rest is the same as in Example 1, except that in step 1), the first modified viscose fiber was prepared in Comparative Preparation Example a2.

[0071] Comparative Example 4

[0072] The rest is the same as in Example 1, except that in step 2), the second modified viscose fiber is prepared as in comparative preparation example b2.

[0073] The nonwoven fabrics of the above embodiments and comparative examples were subjected to the following performance tests:

[0074] Liquid penetration time: determined according to standard GB / T 24218 Textiles - Nonwovens Test Method.

[0075] Moisture reabsorption: Determined according to standard GB / T 24218 Textiles - Nonwovens Test Methods.

[0076] Water absorption resistance: The water absorption is tested according to the standard GB / T 23320-2009 Textiles - Determination of water absorption resistance - Turning absorption method. The lower the water absorption, the better the water absorption resistance.

[0077] Table 1

[0078] Example 1 1.24 3.3 8.6 Example 2 1.26 3.4 8.8 Example 3 1.75 3.7 9.1 Example 4 1.58 3.9 8.8 Example 5 1.72 4.2 9.3 Comparative Example 1 2.17 5.3 10.5 Comparative Example 2 3.97 4.5 7.5 Comparative Example 3 5.21 6.6 11.9 Comparative Example 4 2.88 4.8 7.7

[0079] As can be seen from Table 1, the nonwoven fabric prepared by the present invention is not prone to backflow, has a small amount of backflow, is wet-friendly but does not absorb water, and can quickly allow water to pass through.

[0080] The above detailed description is a specific description of one of the feasible embodiments of the present invention. This embodiment is not intended to limit the patent scope of the present invention. All equivalent implementations or modifications that do not depart from the present invention should be included within the scope of the technical solution of the present invention.

Claims

1. A composite structure spunlace nonwoven fabric for the surface layer of a diaper, comprising a first fiber web layer and a second fiber web layer entangled by spunlace, characterized in that, The first fiber web layer comprises polyester fiber and first modified viscose fiber in a mass ratio of 100:15-20, and the second fiber web layer comprises second modified viscose fiber and kapok fiber in a mass ratio of 50-70:30-50. The modifier for the first modified viscose fiber is an alkyl silane coupling agent, and the amount of the alkyl silane coupling agent is 10-15 wt% of the viscose fiber. The modifier for the second modified viscose fiber is a quaternary ammonium salt silane coupling agent, and the amount of the quaternary ammonium salt silane coupling agent is 3-5 wt% of the viscose fiber. The first modified viscose fiber is manufactured by a method comprising the following steps. The modified viscose fiber is prepared by adding an alcohol-water mixture to a reaction vessel to adjust the pH, adding an alkylsilane coupling agent for hydrolysis, obtaining a hydrolysate, immersing the viscose fiber in the hydrolysate, heating and maintaining the temperature for 1-3 hours, turning it over once every 15-20 minutes, filtering, washing, and drying.

2. The composite structure spunlace nonwoven fabric for the surface layer of the diaper according to claim 1, characterized in that, The alkylsilane coupling agent is selected from one or a combination of two or more of octyltrimethoxysilane, n-decyltrimethoxysilane, butyltrimethoxysilane, ethyltrimethoxysilane, methyltrimethoxysilane, and propyltrimethoxysilane.

3. The composite structure spunlace nonwoven fabric for the surface layer of the diaper according to claim 1, characterized in that, The quaternary ammonium salt silane coupling agent is selected from one or a combination of two or more of dimethyloctadecyl[3-(trimethoxysilyl)propyl]ammonium chloride, 2-methacryloyloxyethyltrimethylammonium chloride, and 4-vinylbenzyldimethyl-(3-trimethoxysilyl)propyl)ammonium chloride.

4. The composite structure spunlace nonwoven fabric for the surface layer of the diaper according to claim 1, characterized in that, The areal density of the first and second fiber web layers is 15-30 g / m². 2 The areal density of the composite spunlace nonwoven fabric used for the surface layer of the diaper is 30-50 g / m². 2 .

5. The composite structure spunlace nonwoven fabric for the surface layer of diapers according to claim 1, characterized in that, The viscose fiber has a fineness of 1-1.5 dtex and a length of 30-40 mm; the kapok fiber has a fineness of 1-1.5 dtex and a length of 15-30 mm; and the polyester fiber has a fineness of 1-2 dtex and a length of 30-40 mm.

6. The composite structure spunlace nonwoven fabric for the surface layer of the diaper according to claim 1, characterized in that, The cross-sectional shape of the polyester fiber is selected from one of the following: cross-shaped, circular, triangular, and I-shaped.

7. The method for preparing the composite structure spunlace nonwoven fabric for the surface layer of diapers according to any one of claims 1-6, characterized in that, Includes the following steps: 1) The polyester fiber and the first modified viscose fiber are opened, mixed, and combed separately to form the first fiber web; 2) The second modified viscose fiber and kapok fiber are opened, mixed, and combed separately to form a second fiber web; 3) The first fiber web and the second fiber web are combined, reinforced by hydroentangling, dried and rolled to obtain the composite structure hydroentangled nonwoven fabric for the surface layer of diapers.