A latex absorbent core, a sanitary napkin, and a method for preparing the same.

Abstract

This invention discloses a latex absorbent core, a sanitary napkin, and a method for preparing the same, relating to the field of hygiene products technology. The absorbent core comprises an upper core layer and a lower core layer that are pressed together. The upper core layer comprises the following raw materials: hydrophilic polyurethane and polyethylene / polyester composite fiber. The lower core layer comprises the following raw materials: SAP resin and polyvinyl alcohol. The latex absorbent core prepared by this invention can quickly absorb and firmly lock in menstrual blood, and has excellent softness and breathability.

Description

Technical Field

[0001] This invention relates to the field of hygiene products technology, and in particular to a latex absorbent core, a sanitary napkin, and a method for preparing the same. Background Technology

[0002] Superabsorbent polymer (SAP) is a functional polymer material capable of absorbing and retaining hundreds or even thousands of times its own weight in liquid. It rapidly swells to form a gel after absorbing water, and the water is difficult to squeeze out even under external force. It possesses excellent water absorption, water retention, and absorption speed, and is widely used in the field of hygiene products.

[0003] SAP resin absorbs a large amount of water. After absorbing water, the SAP resin core expands in volume. The expanded particles will crowd out the original pores, etc. Moreover, SAP resin has no resilience and may block the original flow channels, causing subsequent liquids to be unable to penetrate, resulting in side leakage and backflow problems. Summary of the Invention

[0004] In view of the defects of the prior art, the purpose of this invention is to provide a latex absorbent core, a sanitary napkin and its preparation method, so as to solve the problem of pore blockage in the absorbent core after it absorbs water.

[0005] One of the objectives of this invention is achieved through the following technical solution: A latex absorbent core includes an integrally pressed upper core layer and a lower core layer. The upper core layer comprises hydrophilic polyurethane and polyethylene / polyester composite fibers, and the lower core layer comprises SAP resin and polyvinyl alcohol.

[0006] Preferably, the upper core layer comprises the following raw materials in parts by weight: 70-80 parts hydrophilic polyurethane and 8-12 parts polyethylene / polyester composite fiber, wherein the polyethylene / polyester composite fiber has a fineness of 3-6 denier and a length of 30-40 mm.

[0007] Preferably, the lower core layer comprises the following raw materials in parts by weight: 70-80 parts SAP resin and 2-3 parts polyvinyl alcohol.

[0008] Preferably, the preparation method of the upper core layer includes the following steps: adding polyethylene / polyester composite fibers to hydrophilic polyurethane prepolymer, stirring evenly, then adding deionized water, mixing thoroughly, then immediately pouring into a foaming mold, letting stand for 10-15 minutes, and maturing at 60-70℃ for 1-2 hours to obtain the upper core layer.

[0009] Preferably, the preparation method of the lower core layer includes the following steps: (1) dissolving polyvinyl alcohol in deionized water at 90-95°C to obtain a polyvinyl alcohol solution with a concentration of 10-15% for later use; (2) granulating and screening SAP resin to obtain SAP resin particles with a particle size of 200-300μm; (3) uniformly spreading the SAP resin particles on the breathable fabric, and then pressing the SAP resin particles down with a pressure plate to obtain the lower core, spraying the polyvinyl alcohol solution into the lower core, drying and removing water to obtain the lower core layer.

[0010] The second objective of this invention is achieved by the following technical solution: A method for preparing a latex absorbent core involves atomizing and spraying a polyvinyl alcohol solution onto a lower core, aligning an upper core layer onto the lower core, pressing the layers together, and finally drying to remove water, thereby obtaining the latex absorbent core.

[0011] The third objective of this invention is achieved by the following technical solution: A sanitary napkin, from bottom to top, includes a bottom film, an absorbent core, and a skin-friendly surface layer.

[0012] The fourth objective of this invention is achieved by the following technical solution: A method for preparing a sanitary napkin involves sequentially bonding the bottom film, the latex absorbent core, and the skin-friendly surface layer to obtain the sanitary napkin.

[0013] The beneficial effects of this invention are: (1) Hydrophilic polyurethane is used as the upper layer of the absorbent core. Hydrophilic polyurethane is made by foaming and curing liquid polymer raw materials. It is a liquid absorbent core. Compared with SAP resin, hydrophilic polyurethane has a latex texture, better feel and touch, is thinner, does not backflow, does not clump, and the surface is easier to keep dry. Polyethylene / polyester composite fiber is added to hydrophilic polyurethane. The hydrophilicity of polyethylene / polyester composite fiber is not as good as that of water-based polyurethane. Therefore, during preparation, the location of polyethylene / polyester composite fiber is more likely to have flow guide holes. When the upper core layer absorbs water, the liquid flows downward under the guidance of polyethylene / polyester composite fiber. The polyethylene / polyester composite fiber supports the hydrophilic polyurethane, so that the upper core does not collapse after absorbing liquid, reducing the blockage of flow guide holes.

[0014] (2) Polyvinyl alcohol is added to the lower core layer as a blood affinity agent to promote the absorption of the lower core layer and avoid upward backflow.

[0015] (3) Granulate the SAP resin, atomize and spray the polyvinyl alcohol solution onto the lower core, and press the upper core layer onto the lower core. Then dry it. After the moisture evaporates, the polyvinyl alcohol forms a solid "bonding point" at the fiber intersection, locking the upper core layer and the lower core layer together. Detailed Implementation

[0016] To make the technical problems solved by the invention, the technical solutions and the beneficial effects clearer, the invention will be further described below in conjunction with the embodiments. Example 1

[0017] This embodiment provides a latex absorbent core, comprising an integrally pressed upper core layer and a lower core layer. The upper core layer comprises the following raw materials by weight: 75 parts hydrophilic polyurethane and 10 parts polyethylene / polyester composite fiber. The polyethylene / polyester composite fiber has a fineness of 3-6 denier and a length of 30-40 mm. The lower core layer comprises the following raw materials by weight: 75 parts SAP resin and 2.5 parts polyvinyl alcohol.

[0018] Example 2 This embodiment provides a latex absorbent core, comprising an integrally pressed upper core layer and a lower core layer. The upper core layer comprises the following raw materials by weight: 80 parts hydrophilic polyurethane and 12 parts polyethylene / polyester composite fiber. The polyethylene / polyester composite fiber has a fineness of 3-6 denier and a length of 30-40 mm. The lower core layer comprises the following raw materials by weight: 80 parts SAP resin and 3 parts polyvinyl alcohol. Example 3

[0019] This embodiment provides a latex absorbent core, comprising an integrally pressed upper core layer and a lower core layer. The upper core layer comprises the following raw materials by weight: 70 parts hydrophilic polyurethane and 8 parts polyethylene / polyester composite fiber. The polyethylene / polyester composite fiber has a fineness of 3-6 denier and a length of 30-40 mm. The lower core layer comprises the following raw materials by weight: 70 parts SAP resin and 2 parts polyvinyl alcohol.

[0020] The preparation methods of the absorber cores in Examples 1-3 include the following steps: S1. Preparation of the upper core layer: Add polyethylene / polyester composite fiber to hydrophilic polyurethane prepolymer, stir evenly, then add deionized water, mix thoroughly, and immediately pour into a foaming mold, let stand for 15 minutes, and cure at 70℃ for 2 hours to obtain the upper core layer. S2. Raw material pretreatment: The SAP resin is granulated and screened to obtain SAP resin particles with a particle size of 200-300μm. S3. Preparation of the lower core: SAP resin particles are evenly spread on the breathable fabric, and then the SAP resin particles are pressed down with a pressure plate to obtain the lower core. S4. Preparation of the lower core layer: Dissolve polyvinyl alcohol in deionized water at 90°C to obtain a 10% polyvinyl alcohol solution. Atomize the polyvinyl alcohol solution and spray it evenly onto the lower core to obtain the lower core layer. S4. Preparation of latex absorbent core: Align the upper core layer with a thickness of 2mm and place it on the lower core layer with a thickness of 2mm. Then, after pressing, dry to remove water to obtain the latex absorbent core.

[0021] Comparative Example 1 Compared with Example 1, the difference of Comparative Example 1 is that, in the preparation process of the lower core layer, 75 parts of SAP resin were directly extruded to obtain the lower composite layer.

[0022] Comparative Example 2 The difference between Comparative Example 2 and Example 1 is that the upper core layer does not include polyethylene / polyester composite fibers.

[0023] Comparative Example 3 Compared with Example 1, Comparative Example 3 differs in that the lower core layer does not include polyvinyl alcohol, thus eliminating the need for spraying polyvinyl alcohol solution during the preparation of the absorbent core.

[0024] Comparative Example 4 Compared with Example 1, the difference in Comparative Example 4 is that the lower core layer is replaced with an upper core layer of the same thickness.

[0025] The absorbent cores of Examples 1-3 and Comparative Examples 1-4 were tested for touch sensitivity and absorption speed. The specific steps were as follows: The absorbent core was laid flat on the operating table. Menstrual blood simulation solution at (23±1)℃ was injected into the sanitary napkin through a long tube to about two-thirds of the front end. 3ml of menstrual blood simulation solution was injected each time. The absorption time S1 was recorded from visual contact with the sanitary napkin to complete absorption in the long tube. After standing for one minute, the surface of the sanitary napkin was touched with the back of the hand, and the first touch sensation was recorded. The above actions were repeated, and the second absorption time S2 was recorded. After standing for one minute, the surface of the sanitary napkin was touched with the back of the hand, and the second touch sensation was recorded. The above actions were repeated again, and the third absorption time S3 was recorded. After standing for one minute, the surface of the sanitary napkin was touched with the back of the hand, and the third touch sensation was recorded. The absorbency of the absorbent cores of Examples 2-4 and Comparative Examples 1-5 was tested, specifically according to the test steps for the determination of absorbency ratio in the "Sanitary Napkin (including Panty Liners) Standard GB / T 8939-2018".

[0026] The results of tests on touch feel, absorption speed, and water absorption capacity are shown in Table 1.

[0027] Table 1. Test results of the absorber cores in Examples 1-3 and Comparative Examples 1-4

[0028] In Examples 1-3, the absorbent cores felt dry and free of foreign objects after three absorption cycles. The first absorption time was between 2.16 and 2.26 seconds, the second absorption time was between 4.85 and 4.95 seconds, and the third absorption time was between 10.44 and 10.97 seconds. The water absorption amount was between 43.58 and 45.12 g.

[0029] As shown in the table above, the absorption times of Comparative Example 1 were all longer than those of Example 1. This indicates that the absorbent core obtained by direct extrusion molding of SAP resin has a poorer liquid absorption effect than the absorbent core obtained by extrusion molding of SAP resin granules, and its water absorption capacity is also inferior. The absorption effects of Comparative Examples 3-5 were all inferior to those of Example 2. This indicates that the lack of polyethylene / polyester composite fiber in the upper core layer, the lack of polyvinyl alcohol in the lower absorbent layer, or the simple upper core layer cannot achieve the rapid absorption effect of this invention.

[0030] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention shall fall within the protection scope of the present invention.

Claims

1. A latex absorbent core, characterized in that, The product comprises an integrally pressed upper core layer and a lower core layer. The upper core layer comprises the following raw materials: hydrophilic polyurethane and polyethylene / polyester composite fiber. The lower core layer comprises the following raw materials: SAP resin and polyvinyl alcohol.

2. The latex absorbent core according to claim 1, characterized in that, The upper core layer comprises the following raw materials by weight: 70-80 parts hydrophilic polyurethane and 8-12 parts polyethylene / polyester composite fiber, wherein the polyethylene / polyester composite fiber has a fineness of 3-6 denier and a length of 30-40 mm.

3. The latex absorbent core according to claim 1, characterized in that, The lower core layer comprises the following raw materials in parts by weight: 70-80 parts SAP resin and 2-3 parts polyvinyl alcohol.

4. The latex absorbent core according to claim 1, characterized in that, The preparation method of the upper core layer includes the following steps: adding polyethylene / polyester composite fibers to hydrophilic polyurethane prepolymer, stirring evenly, then adding deionized water, mixing thoroughly, and then immediately pouring into a foaming mold, letting stand for 10-15 minutes, and maturing at 60-70℃ for 1-2 hours to obtain the upper core layer.

5. A latex absorbent core according to claim 1, characterized in that, The preparation method of the lower core layer includes the following steps: (1) dissolving polyvinyl alcohol in deionized water at 90-95℃ to obtain a polyvinyl alcohol solution with a concentration of 10-15% for later use; (2) granulating and screening SAP resin to obtain SAP resin particles with a particle size of 200-300μm; (3) uniformly spreading the SAP resin particles on the breathable fabric, and then pressing the SAP resin particles down with a pressure plate to obtain the lower core, spraying the polyvinyl alcohol solution into the lower core, drying and removing water to obtain the lower core layer.

6. The method for preparing the absorber core according to any one of claims 5, characterized in that, After the polyvinyl alcohol solution is atomized and sprayed onto the lower core, the upper core layer is aligned and placed on the lower core, then pressed together, and finally dried to remove water, to obtain the latex absorbent core.

7. A sanitary napkin, characterized in that, From bottom to top, it comprises a base film, an absorbent core as described in any one of claims 1-5, and a skin-friendly surface layer.

8. A method for preparing a sanitary napkin as described in claim 7, characterized in that, The sanitary napkin is made by bonding the bottom film, the latex absorbent core, and the skin-friendly surface layer in sequence.

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