Nonwoven fabric for diapers or sanitary napkins, preparation method and application thereof

Abstract

The invention provides a nonwoven fabric for diapers or sanitary napkins, a preparation method and application thereof. The nonwoven fabric is made of three layers of fiber webs, upper, middle and lower, which are sequentially overlapped and reinforced by spunlace. The upper fiber web comprises the following raw materials: PET fiber and PVA fiber; the lower fiber web comprises the following raw materials: PET fiber and PVA fiber; the middle fiber web comprises the following raw materials: PET fiber and grafted modified PET fiber; the grafting modifier of the grafted modified PET fiber is glycyrrhizic acid, and the grafted modified PET fiber is obtained by grafting glycyrrhizic acid on the surface of hydrolyzed PET fiber. The grafted modified PET fiber has good hygroscopicity and antibacterial properties. The hygroscopicity of the nonwoven fabric composited with the three-layer fiber web presents a trend of being strong in the middle and weak at both sides, so that the nonwoven fabric is hygroscopic but not water-absorbent, and liquid can penetrate quickly, thereby maintaining the dryness of the skin-contacting surface; the nonwoven fabric prepared by the three-layer fiber web has a firm overall structure, will not be delaminated, and has good air permeability; and is suitable for being used as the surface layer of diapers and sanitary napkins.

Description

Technical Field

[0001] The invention belongs to the technical field of sanitary products, and in particular relates to a nonwoven fabric for diapers or sanitary napkins, a preparation method and application thereof. Background Art

[0002] Diapers mainly include a surface layer, a drainage layer, a core layer, and a leak-proof bottom film. Each layer of the diaper structure has its own function. The surface layer is the layer that directly contacts the human skin and has a critical impact on the user. It must not only be soft and breathable, but also have the property of not absorbing water so that urine can quickly penetrate it to keep the skin-contacting surface dry. At present, the surface layer materials of diapers mainly include non-woven fabrics made of hydrophobic fibers such as polypropylene, polyethylene, and PET. This is mainly because hydrophobic fibers such as polypropylene, polyethylene, and PET are hydrophobic, which can allow urine to quickly penetrate the surface layer of the diaper and enter the drainage layer.

[0003] For example, patent CN110341243B discloses a diaper with high air permeability, which includes a breathable surface layer, a grid-shaped composite core layer and a hygroscopic outer layer from top to bottom; the breathable surface layer includes water-permeable skin-friendly non-woven fabrics with different hydrophilicity from top to bottom, and the hydrophilic non-woven fabrics and the curly moisture-proof non-woven fabrics are formed by hot air bonding; the water-permeable skin-friendly non-woven fabrics are prepared by the following weight parts of raw materials: 100 parts of polypropylene, 0.4-0.8 parts of titanium dioxide, 0.1-1 parts of polyethylene, 0.2-1 parts of erucic acid amide, and 10 parts of ethylene propylene copolymer. This technology is a hydrophobic non-woven fabric made of PE, PP and ethylene propylene copolymer. The surface layer of the diaper made of it is soft, breathable and dry, but the diaper has poor hygroscopicity, which leads to a long time for urine to penetrate the surface layer and urine is easy to penetrate back to the surface layer, resulting in low dryness of the diaper, forming a humid environment at the skin contact point, and long-term wearing is not good for the skin health of users. Patent CN105963081B discloses a baby diaper and a preparation method thereof, wherein the baby diaper is mainly prepared by using a modified polypropylene microfiber nonwoven film as a surface hydrophilic nonwoven fabric, a thickened fluffy guide layer nonwoven fabric, an absorption layer and an anti-seepage bottom layer, and a polypropylene slice with a melt index of 25-40g / 10min is used, and a modified polypropylene microfiber nonwoven film is prepared by adding a chain scissor and a hydrophilic agent as the surface nonwoven fabric of the baby diaper. This technology shortens the urine penetration time of the surface layer by adding a small amount of hydrophilic additives, but the hydrophilic agent penetrates from the surface layer into the core layer with urine, and urine is still easy to penetrate back to the surface layer. Therefore, it is of great significance to improve the comfort of users to find a nonwoven fabric that is both hydrophilic and non-absorbent, can make urine penetrate quickly, is not easy to penetrate back, and has good dryness to manufacture diapers.

[0004] There are benzene ring chains and methylene chains in the macromolecular chain of PET. The combination of rigidity and flexibility makes PET fiber have good mechanical properties. However, due to the lack of hydrophilic groups in the macromolecular chain of PET, the hygroscopicity of its fiber is very low, and the moisture regain is only about 0.4%. PET has been industrialized for a long time and has a high level of production technology. It can be prepared into non-woven fabrics with the above-mentioned performance requirements through chemical, physical modification or molecular design methods. Summary of the invention

[0005] To solve the above problems, the present invention provides a non-woven fabric for diapers or sanitary napkins, a preparation method and an application thereof. The non-woven fabric comprises three layers of fiber webs, namely, an upper layer, a middle layer and a lower layer. The upper and lower layers are made of the same material and are both made of PET fibers and PVA fibers. The middle layer is made of PET fibers and grafted modified PET fibers, wherein the grafted modifier is glycyrrhizic acid. The PET grafted and modified by glycyrrhizic acid has good hygroscopicity and antibacterial properties. The hygroscopicity of the non-woven fabric composited with the three-layer fiber web shows a trend of being strong in the middle and weak on both sides, so that the non-woven fabric is wet-loving but not water-absorbent, and the liquid can penetrate quickly, thereby maintaining the dryness of the skin-contacting surface. In addition, the non-woven fabric prepared with the three-layer fiber web has a more uniform surface, a fluffy hand feel, and is soft and skin-friendly.

[0006] In order to achieve the above objectives, the following specific technical solutions are adopted:

[0007] A nonwoven fabric is made of upper, middle and lower fiber webs which are stacked in sequence and reinforced by water spunlace.

[0008] The upper fiber web comprises the following raw materials: PET fiber and PVA fiber;

[0009] The lower fiber web comprises the following raw materials: PET fiber and PVA fiber;

[0010] The middle-layer fiber web comprises the following raw materials: PET fiber and graft-modified PET fiber; the graft-modifying agent of the graft-modified PET fiber is glycyrrhizic acid.

[0011] Furthermore, the nonwoven fabric is made of upper, middle and lower fiber webs stacked in sequence at a mass ratio of 1:1-2:1 and reinforced by hydroentanglement, and the weight of the nonwoven fabric is 20-50g / m 2 ,

[0012] The upper fiber web comprises the following raw materials: 100 parts of PET fiber and 10-14 parts of PVA fiber;

[0013] The lower fiber web comprises the following raw materials: 100 parts of PET fiber and 10-14 parts of PVA fiber;

[0014] The middle-layer fiber web comprises the following raw materials: 100 parts of PET fibers and 55-85 parts of grafted modified PET fibers, wherein the grafting rate of the grafted modified PET fibers is 3.3-4.5 wt %.

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

[0016] S1: heating the alkali solution to a high temperature, adding PET fibers, reacting at a constant temperature, filtering after the reaction, immersing the fibers obtained after filtration in an acid solution, filtering again, washing the fibers obtained after water, and drying for use; the purpose of this step is to allow the PET fibers to have carboxyl groups after hydrolysis so as to react with the hydroxyl-containing compound added in the subsequent steps.

[0017] S2: dissolving the catalyst and the grafting modifier in water to prepare a solution, adding the fiber obtained in step S1 and soaking it, filtering it and placing it in a forced air drying oven, heating it and keeping the temperature constant to react, rinsing it with water after the reaction is completed, and drying it for later use.

[0018] Step S1: the alkali solution is selected from one or a combination of two or more of sodium hydroxide solution and potassium hydroxide solution, the concentration of the alkali solution is 3-7 g / L, the weight ratio of the PET fiber to the alkali solution is 1:4-6, the heating is heated to 80-100°C, the constant temperature reaction time is 10-15 min, the acid solution is hydrochloric acid, the concentration of the acid solution is 1-1.2 mol / L, the acid solution immersion time is 1-3 min, the water washing times are 1-3 times, and the drying is carried out under the conditions of a vacuum degree of 0.05-0.10 MPa and a temperature of 40-60°C;

[0019] In step S2, the catalyst is selected from one or a combination of two or more of aminosulfonic acid, p-toluenesulfonic acid, potassium hydrogen sulfate, titanium chloride, tin chloride, and ferric chloride. The concentration of the catalyst in the solution is 3-5wt%, the concentration of the graft modifier in the solution is 7-10wt%, the soaking time is 5-10min, the heating is increased to 100-150°C for constant temperature, the reaction time is 15-25min, the number of rinses is 1-3 times, and the drying is carried out under the conditions of a vacuum degree of 0.05-0.10MPa and a temperature of 40-60°C.

[0020] The fibers in the upper and lower fiber web materials have a fineness of 1.50-1.70 dtex and a length of 37-51 mm; the fibers in the middle fiber web materials have a fineness of 1.50-1.70 dtex and a length of 20-40 mm.

[0021] The present invention also provides a method for preparing a nonwoven fabric, comprising the following steps:

[0022] 1) The raw materials of the upper and lower fiber webs are respectively taken and subjected to cotton addition, opening, mixing, combing, web forming and web laying to form the upper and lower fiber webs respectively;

[0023] 2) taking the middle layer fiber web raw material and adding cotton, opening, mixing, combing, web forming, and web laying to form the middle layer fiber web;

[0024] 3) The upper, middle and lower fiber webs are stacked step by step on a collecting net curtain in sequence, and the nonwoven fabric is obtained by pre-wetting, compacting, hydroentangling, sorting, dehumidifying, drying and winding.

[0025] Step 1) the web laying is cross-laying;

[0026] Step 2) the web laying is cross-laying;

[0027] Step 3) The hydroentanglement is double-sided hydroentanglement, the number of hydroentanglement heads is 5-10, and the preferred number of hydroentanglement heads is 6. The hydroentanglement pressure of hydroentanglement head No. 1 is 30-40 bar; the hydroentanglement pressure of hydroentanglement head No. 2 is 50-60 bar; the hydroentanglement pressure of hydroentanglement head No. 3 is 90-110 bar; the hydroentanglement pressure of hydroentanglement head No. 4 is 100-115 bar; the hydroentanglement pressure of hydroentanglement head No. 5 is 85-110 bar; the hydroentanglement pressure of hydroentanglement head No. 6 is 85-110 bar; the drying system is a two-stage drying system, and the drying temperature is 85-100°C.

[0028] The present invention also provides the use of the nonwoven fabric as a surface layer in diapers and sanitary napkins.

[0029] Compared with the prior art, the present invention has the following beneficial effects:

[0030] The nonwoven fabric prepared by the present invention comprises three layers of composite fiber webs, namely, an upper layer, a middle layer and a lower layer. The upper layer and the lower layer are made of the same material and are both made of PET fiber and PVA fiber. The middle layer is made of PET fiber and grafted modified PET fiber. The grafted modifier is glycyrrhizic acid. The PET grafted modified by glycyrrhizic acid has good hygroscopicity and certain antibacterial properties. The hygroscopicity of the nonwoven fabric composited with the three-layer fiber web shows a trend of being strong in the middle and weak on both sides, so that the nonwoven fabric is hygroscopic but does not absorb water. The liquid can quickly penetrate and the water absorption is almost zero, thereby maintaining the dryness of the skin-contacting surface.

[0031] Although the three-layer composite fiber web nonwoven fabric of the present invention is a three-layer fiber web, it is reinforced by double-sided spunlace, so the overall structure is firm and will not be delaminated. The double-sided spunlace reinforcement gives the nonwoven fabric a porous structure, which greatly improves the air permeability of the nonwoven fabric.

[0032] The non-woven fabric prepared by the three-layer composite fiber net of the present invention has a uniform surface, a fluffy hand feel, is soft and skin-friendly, and is suitable for being used as the surface layer of diapers and sanitary napkins. DETAILED DESCRIPTION

[0033] The present invention will be further described below in conjunction with specific embodiments, but is not limited to the contents of the specification. Unless otherwise specified, the "parts" described in the embodiments of the present invention are all parts by weight. The reagents used are all commercially available reagents in the art.

[0034] Upper and lower fiber:

[0035] PET fiber was purchased from Taian Ruiyi Shengwei Synthetic Materials Co., Ltd. with a fineness of 1.50 dtex and a length of 50 mm;

[0036] PVA fiber was purchased from Taian Ruiyi Shengwei Synthetic Materials Co., Ltd. with a fineness of 1.60 dtex and a length of 38 mm;

[0037] Middle Fiber:

[0038] PET fiber was purchased from Taian Ruiyi Shengwei Synthetic Materials Co., Ltd. with a fineness of 1.50 dtex and a length of 26 mm;

[0039] The PET fiber for grafting modification was also purchased from Taian Ruiyi Shengwei Synthetic Materials Co., Ltd., with a fineness of 1.50 dtex and a length of 26 mm.

[0040] Preparation of grafted modified PET fibers

[0041] Preparation Example 1

[0042] S1: 60 parts of 5g / L sodium hydroxide solution are heated to 90°C, 10 parts of PET fiber are added, and the reaction is carried out at a constant temperature for 15 minutes. After the reaction is completed, the fiber is filtered, and the fiber obtained after filtration is immersed in 1.0mol / L hydrochloric acid for 3 minutes, filtered again, and the fiber obtained after repeated washing with water for 3 times is dried under the conditions of vacuum degree of 0.10MPa and temperature of 60°C for use;

[0043] S2: Dissolve 5 parts of ferric chloride and 10 parts of glycyrrhizic acid in 85 parts of water to prepare a solution, add the fiber obtained in step S1 and soak for 10 minutes, filter and place in a blast drying oven, heat to 150°C and keep the temperature constant for 15 minutes, rinse with water 3 times after the reaction, and dry at a vacuum degree of 0.10MPa and a temperature of 60°C for use.

[0044] Preparation Example 2

[0045] The rest is the same as Preparation Example 1, except that in step S2, the amount of glycyrrhizic acid used is 7 parts, the amount of ferric chloride used is 3 parts, and the amount of water used in the solution is 90 parts.

[0046] Comparative Preparation Example 1

[0047] The rest is the same as Preparation Example 1, except that an equal amount of polyethylene glycol is used instead of glycyrrhizic acid.

[0048] Preparation of nonwoven fabrics

[0049] Example 1

[0050] 1) 100 parts of PET fibers and 14 parts of PVA fibers are taken, and the upper fiber web is made by adding cotton, opening, mixing, carding, web forming, and cross-laying;

[0051] Take 100 parts of PET fibers and 14 parts of PVA fibers, add cotton, loosen, mix, card, form a web, and cross-lay the web to make a lower fiber web;

[0052] 2) 100 parts of PET fibers and 85 parts of the grafted modified PET fibers prepared in Preparation Example 1 were taken and cotton was added, opened, mixed, carded, web-formed, and cross-laid to form a middle-layer fiber web;

[0053] 3) The three-layer fiber webs prepared in steps 1), 2) and 1) are stacked step by step on a collecting screen in the order of upper, middle and lower at a weight ratio of 1:2:1, and are pre-wetted, compacted, double-sided hydroentangled, sorted, dehumidified, dried and wound. There are 6 hydroentanglement heads, the hydroentanglement pressure of hydroentanglement head No. 1 is 40 bar; the hydroentanglement pressure of hydroentanglement head No. 2 is 60 bar; the hydroentanglement pressure of hydroentanglement head No. 3 is 110 bar; the hydroentanglement pressure of hydroentanglement head No. 4 is 115 bar; the hydroentanglement pressure of hydroentanglement head No. 5 is 110 bar; the hydroentanglement pressure of hydroentanglement head No. 6 is 110 bar, the drying system is a two-stage drying system, the drying temperature of the first-stage drying system is 85°C, and the drying temperature of the second-stage drying system is 100°C, and the weight is 31 g / m 2 of nonwoven fabrics.

[0054] Example 2

[0055] The rest is the same as Example 1, except that the grafted modified PET fiber prepared in Step 2) is the one prepared in Preparation Example 2.

[0056] Example 3

[0057] The rest is the same as Example 1, except that in step 3), the three-layer fiber webs prepared in steps 1), 2) and 1) are stacked step by step on the collecting mesh curtain in the order of upper, middle and lower at a weight ratio of 1:1:1.

[0058] Comparative Example 1

[0059] The rest is the same as Example 1, except that the grafted modified PET fiber prepared in step 2) is prepared in Comparative Preparation Example 1.

[0060] Comparative Example 2

[0061] The rest is the same as Example 1, except that in step 3), the three-layer fiber webs prepared in steps 1), 1), and 2) are stacked step by step on the collecting mesh curtain in the order of upper, middle, and lower at a weight ratio of 1:1:2.

[0062] Comparative Example 3

[0063] The rest is the same as Example 1, except that the middle fiber web prepared in step 2) is replaced by an equal amount of the upper fiber web prepared in step 1).

[0064] The grafted modified PET fibers prepared in the above preparation examples and comparative preparation examples were tested for grafting rate, and the results are shown in Table 1:

[0065] Grafting rate: The grafting rate G is calculated according to the following formula:

[0066] G=(m1-m0) / m0

[0067] Among them, m0 and m1 are the masses of PET fiber before and after grafting modification, respectively.

[0068] Table 1 Grafting rate of Preparation Examples 1-2 and Comparative Preparation Example 1

[0069] project Grafting rate % Preparation Example 1 4.5 Preparation Example 2 3.3 Comparative Preparation Example 1 1.6

[0070] The nonwoven fabrics prepared in the above examples and comparative examples were tested for rewet amount and liquid penetration time. The results are shown in Table 2:

[0071] Rewet volume: The rewet volume is equal to the sum of the liquid return volume and the liquid residual volume. The smaller the rewet volume, the better the dryness of the non-woven fabric. The test is carried out in accordance with the standard GB / T 28004-2011.

[0072] Liquid penetration time: refers to the time required for liquid to pass through the material in the vertical direction. The shorter the liquid penetration time, the better the permeability of the non-woven fabric. The test is carried out in accordance with the standard GB / T 24218.13-2010.

[0073] Table 2 Tests on the rewet amount and liquid penetration time of Examples 1-3 and Comparative Examples 1-3

[0074]

[0075] The nonwoven fabrics prepared in the above examples and comparative examples were tested for their anti-corrosion performance. The results are shown in Table 3.

[0076] The test method is based on the European Pharmacopoeia EP 10.0, 5.1.3. The tested bacteria are: Staphylococcus aureus (ATCC6538), Escherichia coli (ATCC 8739) and Candida albicans (ATCC 10231). 8The three strains were inoculated onto the nonwoven fabrics prepared in the embodiments and comparative examples, and the logarithmic reduction values ​​of these strains were measured after 14 days. The greater the reduction value, the better the antiseptic effect.

[0077] Table 3 Anticorrosion performance test of Examples 1-3 and Comparative Examples 1-3

[0078]

[0079]

[0080] The above detailed description is a specific description of one feasible embodiment of the present invention. The embodiment is not intended to limit the patent scope of the present invention. Any equivalent implementation or modification that does not deviate from the present invention should be included in the scope of the technical solution of the present invention.

Claims

1. A nonwoven fabric for diapers or sanitary napkins, characterized in that: The nonwoven fabric is made of upper, middle and lower fiber webs stacked in sequence and reinforced by water spunlace. The raw materials for preparing the upper fiber web include: PET fiber and PVA fiber; The raw materials for preparing the lower fiber web include: PET fiber and PVA fiber; The raw materials for preparing the middle-layer fiber web include: 100 parts of PET fibers and 55-85 parts of grafted modified PET fibers; the grafted modifier of the grafted modified PET fibers is glycyrrhizic acid, and the grafting rate is 3.3-4.5wt%; the grafted modified PET fibers are obtained by grafting glycyrrhizic acid on the surface of hydrolyzed PET fibers.

2. The nonwoven fabric for diapers or sanitary napkins according to claim 1, characterized in that: The nonwoven fabric is made of upper, middle and lower fiber webs which are stacked in sequence at a mass ratio of 1:1-2:1 and reinforced by water spunlace. The raw materials for preparing the upper fiber web include: 100 parts of PET fiber and 10-14 parts of PVA fiber; The raw materials for preparing the lower fiber web include: 100 parts of PET fibers and 10-14 parts of PVA fibers.

3. The nonwoven fabric for diapers or sanitary napkins according to claim 1, characterized in that: The nonwoven fabric has a grammage of 20-50 g / m 2 .

4. The nonwoven fabric for diapers or sanitary napkins according to claim 1, characterized in that: The grafted modified PET fiber is prepared by a method comprising the following steps: S1: heating the alkali solution to a high temperature, adding the PET fiber, and reacting at a constant temperature. After the reaction is completed, filtering is performed, and the fiber obtained after filtering is immersed in an acid solution, filtered again, and the fiber obtained after washing with water is dried for later use; S2: dissolving the catalyst and the grafting modifier in water to prepare a solution, adding the fiber obtained in step S1 and soaking it, filtering it and placing it in a forced air drying oven, heating it and keeping the temperature constant to react, rinsing it with water after the reaction is completed, and drying it for later use.

5. The nonwoven fabric for diapers or sanitary napkins according to claim 4, characterized in that: The concentration of the alkali solution in step S1 is 3-7 g / L, and the weight ratio of the PET fiber to the alkali solution is 1:4-6.

6. The nonwoven fabric for diapers or sanitary napkins according to claim 4, characterized in that: In step S2, the concentration of the catalyst in the solution is 3-5wt%, the concentration of the graft modifier in the solution is 7-10wt%, the immersion time is 5-10min, the temperature is raised to 100-150°C for constant temperature, and the reaction time is 15-25min.

7. The nonwoven fabric for diapers or sanitary napkins according to claim 1, characterized in that: The fibers in the upper and lower fiber web materials have a fineness of 1.50-1.70 dtex and a length of 37-51 mm; the fibers in the middle fiber web materials have a fineness of 1.50-1.70 dtex and a length of 20-40 mm.

8. The method for preparing the nonwoven fabric for diapers or sanitary napkins according to any one of claims 1 to 7, comprising the following steps: 1) The raw materials of the upper and lower fiber webs are respectively taken and subjected to cotton addition, opening, mixing, combing, web forming and web laying to form the upper and lower fiber webs respectively; 2) Take the middle layer fiber web raw material and add cotton, open, mix, comb, web and lay the web to form the middle layer fiber web; 3) The upper, middle and lower fiber webs are stacked step by step on a collecting net curtain in sequence, and the nonwoven fabric is obtained by pre-wetting, compacting, hydroentangling, sorting, dehumidifying, drying and winding.

9. The preparation method according to claim 8, characterized in that: Step 1) the web laying is cross-lapping; Step 2) the web laying is cross-lapping; Step 3) the spunlace is double-sided spunlace, and the number of spunlace heads is 5-10; the drying system is a two-stage drying system, and the drying temperature is 85-100°C.

10. The preparation method according to claim 9, characterized in that: There are 6 water jet heads, the water jet pressure of water jet head No. 1 is 30-40 bar; the water jet pressure of water jet head No. 2 is 50-60 bar; the water jet pressure of water jet head No. 3 is 90-110 bar; the water jet pressure of water jet head No. 4 is 100-115 bar; the water jet pressure of water jet head No. 5 is 85-110 bar; and the water jet pressure of water jet head No. 6 is 85-110 bar.

11. Use of the nonwoven fabric for diapers or sanitary napkins according to any one of claims 1 to 7 as a surface layer in diapers or sanitary napkins.

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