A multi-layer absorbent structure sanitary napkin and its preparation method

Abstract

The invention discloses a sanitary napkin with a multi-layer absorbent structure and a preparation method thereof. The sanitary napkin comprises, from bottom to top, a base film, a second absorbent layer, a first absorbent layer and a skin-friendly layer. The first absorbent layer comprises the following components in parts by weight: 20 to 40 parts of sodium polyacrylate, 2 to 6 parts of an anticoagulant, 0.8 to 1.4 parts of a fatty acid amide and 0.2 to 0.5 parts of an organic fluorine compound; the second absorbent layer comprises the following components in parts by weight: 20 to 40 parts of sodium polyacrylate, 4 to 8 parts of a hydrophilic additive, 0.8 to 1.4 parts of a fatty acid amide and 0.2 to 0.5 parts of an organic fluorine compound. The prepared sanitary napkin with a multi-layer absorbent structure has good absorption capacity and absorption speed.

Description

Technical Field

[0001] The present invention relates to the technical field of sanitary napkins, in particular to a sanitary napkin with a multi-layer absorbent structure and a preparation method thereof. Background Art

[0002] At present, the surface of existing sanitary napkins will preferentially absorb menstrual blood when used. Since the menstrual blood will gradually coagulate after absorbing blood, the absorption speed and absorption amount of the sanitary napkin will be reduced. At the same time, the coagulated matter may make the user feel as if there is a foreign body in the napkin, affecting the user's experience of use. Summary of the Invention

[0003] In view of the above-mentioned defects in the prior art, the purpose of the present invention is to provide a sanitary napkin with a multi-layer absorbent structure and a preparation method thereof, so as to improve the absorption capacity and absorption speed of the sanitary napkin.

[0004] One of the purposes of the present invention is achieved by the following technical solution:

[0005] A multi-layer absorbent sanitary napkin comprises, from bottom to top, a base film, a second absorbent layer, a first absorbent layer and a skin-friendly layer. The first absorbent layer comprises the following components in parts by weight: 20 to 40 parts of sodium polyacrylate, 2 to 6 parts of an anticoagulant, 0.8 to 1.4 parts of a fatty acid amide and 0.2 to 0.5 parts of an organic fluorine compound; the second absorbent layer comprises the following components in parts by weight: 20 to 40 parts of sodium polyacrylate, 4 to 8 parts of a hydrophilic additive, 0.8 to 1.4 parts of a fatty acid amide and 0.2 to 0.5 parts of an organic fluorine compound.

[0006] The skin-friendly layer is made of cotton and other materials, which is comfortable and skin-friendly. The bottom film is made of breathable material, which prevents liquid seepage while ensuring moisture penetration. The skin-friendly layer and the bottom film are both made using existing technologies and will not be described here.

[0007] The first absorption layer contacts the menstrual blood before the second absorption layer. The anticoagulant in the first absorption layer can reduce the blood coagulation ability of the first absorption layer, prevent the menstrual blood from coagulating quickly, and avoid the menstrual blood from being blocked in the first absorption layer, providing more time and opportunities for the menstrual blood to seep into the second absorption layer. At the same time, the hydrophilic additive in the second absorption layer can promote the rapid absorption of menstrual blood in the second absorption layer. The second absorption layer cooperates with the first absorption layer to improve the absorption amount, absorption frequency and absorption efficiency of the sanitary napkin.

[0008] An organic fluorine compound is added to the two absorption layers. The molecular structure of the organic fluorine compound contains a large number of fluorine atoms. Fluorine atoms have an extremely small atomic radius and extremely strong electronegativity. Therefore, the organic fluorine compound has good chemical stability and surface activity, as well as strong temperature resistance. During the preparation process, it is not destroyed by the cross-linking structure of other components. The organic fluorine compound can form a protective layer on the surface of sodium polyacrylate, thereby improving its surface hydrophilicity.

[0009] A small amount of fatty acid amide is added to the two absorption layers. Fatty acid amide has lubricating and anti-sticking effects, which can further promote the infiltration of menstrual blood. At the same time, fatty acid amide also has certain antibacterial and anti-inflammatory effects.

[0010] Preferably, the thickness of the first absorption layer is 1 to 2 times that of the second absorption layer.

[0011] Preferably, the anticoagulant is at least one of sodium citrate, ethylenediaminetetraacetic acid and heparin.

[0012] Preferably, the organic fluorine compound is methyl perfluoroisobutyl ether.

[0013] Preferably, the hydrophilic additive is polyvinyl alcohol.

[0014] Preferably, the preparation method of the first absorption layer comprises the following steps: firstly mixing sodium polyacrylate, an anticoagulant, a fatty acid amide and an organic fluorine compound, then adding them to water, placing the mixture in a high-pressure steam cooker, heating at 100-110°C, and mixing to obtain a first mixed liquid with a uniform texture; inverting the first mixed solution into a mold, performing electron beam radiation cross-linking treatment to obtain a first mixed copolymer, and freeze-drying, crushing and screening the first mixed copolymer to obtain the first absorption layer.

[0015] Preferably, the preparation method of the second absorption layer comprises the following steps: firstly mixing sodium polyacrylate, a hydrophilic additive, a fatty acid amide and an organic fluorine compound, then adding them to water, placing the mixture in a high-pressure steam cooker, heating at 100-110°C, and mixing to obtain a second mixed liquid with a uniform texture; inverting the second mixed solution into a mold, performing electron beam radiation cross-linking treatment to obtain a second mixed copolymer, and freeze-drying, crushing and screening the second mixed copolymer to obtain the second absorption layer.

[0016] The first and second absorbent layers are cross-linked using electron beam radiation. Alternatively, cross-linking with a cross-linking agent is also possible. Furthermore, the first and second absorbent layers are freeze-dried to completely remove moisture from the absorbent layers. The screened absorbent particles themselves possess a porous structure. The absorbent layer is formed by stacking and pressing a number of these absorbent particles. The resulting porous structure provides a channel for menstrual blood, allowing it to penetrate smoothly downward.

[0017] Preferably, the first absorption layer further comprises 1 to 2 parts of gelatin.

[0018] Gelatin, a partially hydrolyzed product of collagen, is more skin-friendly. Dried gelatin adsorbs onto the absorbent particles, providing mechanical strength and supporting their porous structure. This reduces the tendency of the first absorbent layer to collapse when exposed to blood, preventing a foreign body sensation and further enhancing the user experience. Gelatin also absorbs water, helping the first absorbent layer absorb menstrual blood. Furthermore, at low levels, gelatin is colorless and transparent, and does not affect the color of the first absorbent layer.

[0019] Preferably, the preparation method of the first absorption layer includes the following steps: first mixing sodium polyacrylate, anticoagulant, fatty acid amide and organic fluorine compound, then adding them to water, placing them in a high-pressure steam cooker, heating at 100-110°C, and mixing to obtain a first mixed liquid with a uniform texture; inverting the first mixed solution into a mold, performing electron beam radiation cross-linking treatment to obtain a first mixed copolymer, drying, crushing and screening the first mixed copolymer to obtain an absorption masterbatch of 200-400 μm; adding gelatin to water, stirring and dissolving it at 70°C to prepare a 3wt% gelatin aqueous solution, immersing the absorption masterbatch in the gelatin aqueous solution under negative pressure for 10-20 minutes, taking it out, draining off excess liquid, and then freezing it at -80°C, and then freeze-drying it to obtain the first absorption layer.

[0020] The negative pressure can be -0.04Mpa, -0.05Mpa, etc. Under negative pressure conditions, the gelatin aqueous solution can completely penetrate into the interior of the absorbent masterbatch and adsorb on the internal pores. After freeze-drying, the moisture is completely removed. The gelatin provides a certain mechanical strength for the absorbent masterbatch. At the same time, the amount of gelatin used is controlled to increase the strength of the first absorption layer to a certain extent while avoiding discomfort caused by the first absorption layer being too hard.

[0021] The second object of the present invention is achieved by adopting the following technical solution:

[0022] According to the above-mentioned method for preparing a multi-layer absorbent structure sanitary napkin, the method includes the following steps: cutting the base film, the second absorbent layer, the first absorbent layer and the skin-friendly layer, and then placing them in a bonding device in order, and pasting them in sequence by the bonding device to prepare a multi-layer absorbent structure sanitary napkin.

[0023] The beneficial effects of the present invention are:

[0024] The anticoagulant in the first absorption layer can reduce the blood coagulation ability of the first absorption layer and prevent the menstrual blood from clotting quickly. The first absorption layer contacts the menstrual blood earlier than the second absorption layer, avoiding the blockage of menstrual blood in the first absorption layer and reducing the phenomenon of the first absorption layer collapsing into clumps when encountering blood during use, providing more time and opportunities for the menstrual blood to seep into the second absorption layer. At the same time, the hydrophilic additive in the second absorption layer can promote the rapid absorption of menstrual blood in the second absorption layer. The second absorption layer cooperates with the first absorption layer to improve the absorption amount, absorption frequency and absorption efficiency of the sanitary napkin, avoid the foreign body sensation, and further improve the feeling of use. DETAILED DESCRIPTION

[0025] In order to make the technical problems, technical solutions and beneficial effects solved by the invention more clearly understood, the invention is further described below in conjunction with the embodiments. It should be noted that the raw materials, equipment, etc. used in the following embodiments can be obtained by purchase unless otherwise specified.

[0026] Examples 1 to 4

[0027] Raw materials were weighed according to the ratios in Table 1, and sanitary napkins were made according to the preparation method in Table 1 to obtain sanitary napkins of different embodiments. See Table 1 for details:

[0028] Table 1 Raw material ratios of Examples 1 to 4 and Comparative Examples 1 to 7

[0029]

[0030]

[0031] The preparation method of the first absorption layer in Examples 1 to 3 of Table 1 is as follows: weigh the components of the formula amount for use, first mix sodium polyacrylate, anticoagulant, fatty acid amide and organic fluorine compound, and then add them to water, wherein the mass ratio of sodium polyacrylate to water is 1:3, and then place them in a high-pressure steam cooker, heat at 100-110° C. for 1 hour, and mix to obtain a first mixed liquid with a uniform texture. The first mixed solution is inverted in a mold and subjected to electron beam radiation cross-linking treatment, wherein the electron beam energy is 2 MeV, the beam current is 1000 μA, and the cumulative radiation dose is 45 kGy to obtain a first mixed copolymer. The first mixed copolymer is placed in a freezer at -80° C. for 24 hours, freeze-dried for 48 hours, and then crushed and sieved to obtain first absorption particles of 200-400 μm. A plurality of first absorption particles are stacked and pressed to obtain the first absorption layer.

[0032] The preparation method of the first absorption layer in Example 4 of Table 1 is as follows: weigh the components of the formula amount for use, first mix sodium polyacrylate, anticoagulant, fatty acid amide and organic fluorine compound, and then add them to water, wherein the mass ratio of sodium polyacrylate to water is 1:3, then place it in a high-pressure steam cooker, heat it at 100-110°C for 1 hour, and mix to obtain a first mixed liquid with uniform texture, invert the first mixed solution in a mold, and perform electron beam radiation cross-linking treatment, wherein the electron beam energy is 2MeV, the beam current is 1000μA, and the cumulative radiation is 1000μA. The dosage is 45kGy to obtain a first mixed copolymer, which is placed in an oven and dried at 50°C for 24 hours, and then crushed and sieved to obtain an absorbent masterbatch of 200-400μm; at 70°C, the absorbent masterbatch is immersed in a 3wt% gelatin aqueous solution under a negative pressure of -0.04Mpa for 20 minutes, then taken out, and the excess liquid is drained, and then placed at -80°C for freezing for 24 hours, and freeze-dried for 48 hours to obtain first absorbent particles, and a number of first absorbent particles are stacked and pressed to obtain a first absorbent layer.

[0033] The preparation method of the second absorption layer in Examples 1 to 4 of Table 1 is as follows: weighing the components in the formula amount for use, first mixing sodium polyacrylate, a hydrophilic additive, a fatty acid amide and an organic fluorine compound, and then adding them to water, wherein the mass ratio of sodium polyacrylate to water is 1:3, then placing the mixture in a high-pressure steam cooker, heating at 100-110° C. for 1 hour, and mixing to obtain a second mixed liquid with a uniform texture, inverting the second mixed solution into a mold, and performing electron beam radiation cross-linking treatment, wherein the electron beam energy is 2 MeV, the beam current is 1000 μA, and the cumulative radiation dose is 45 kGy, to obtain a second mixed copolymer, placing the second mixed copolymer in a freezer at -80° C. for 24 hours, freeze-drying for 48 hours, and then crushing and sieving to obtain second absorption particles of 300-500 μm, and stacking and pressing a plurality of the second absorption particles to obtain a second absorption layer.

[0034] The preparation method of the multi-layer absorbent structure sanitary napkin in Examples 1 to 4 of Table 1 is as follows: the base film, the second absorbent layer, the first absorbent layer and the skin-friendly layer are cut and then placed in a bonding device in order, and the bonding device is used to bond them in sequence to obtain a multi-layer absorbent structure sanitary napkin, wherein the thickness of the first absorbent layer is twice that of the second absorbent layer.

[0035] In Examples 1 to 4 in Table 1, sodium citrate was used as the anticoagulant, methyl perfluoroisobutyl ether was used as the organic fluorine compound, and polyvinyl alcohol was used as the hydrophilic additive.

[0036] Comparative Example 1

[0037] The difference between Comparative Example 1 and Example 1 is that the second absorption layer is replaced by the first absorption layer, and the second absorption layer and the first absorption layer are combined into one absorption layer, which adopts the raw materials, proportions and preparation method of the first absorption layer.

[0038] Comparative Example 2

[0039] The difference between Comparative Example 2 and Example 1 is that the first absorption layer is replaced by the second absorption layer, the first absorption layer and the second absorption layer are combined into one absorption layer, and the absorption layer adopts the raw materials, proportions and preparation method of the second absorption layer.

[0040] Comparative Example 3

[0041] The difference between Comparative Example 3 and Example 1 is that no anticoagulant is added to the first absorption layer.

[0042] Comparative Example 4

[0043] The difference between Comparative Example 4 and Example 1 is that no hydrophilic additive is added to the second absorption layer.

[0044] Comparative Example 5

[0045] The difference between Comparative Example 5 and Example 1 is that no organic fluorine compound is added to the first absorption layer and the second absorption layer.

[0046] Comparative Example 6

[0047] The difference between Comparative Example 6 and Example 1 is that no fatty acid amide is added to the first absorption layer and the second absorption layer.

[0048] Comparative Example 7

[0049] The difference between Comparative Example 7 and Example 4 is that the amount of gelatin added to the first absorption layer is 2.5 parts.

[0050] The appearance, touch, absorption rate and rewet amount of the sanitary napkins of Examples 1 to 4 and Comparative Examples 1 to 7 were tested as follows:

[0051] Appearance inspection: Observe and record the color and appearance of the sanitary napkins with the naked eye. Examples 1 to 4 and Comparative Examples 1 to 7 are the same in appearance and color.

[0052] Tactile sensation and absorption speed test: Lay the sanitary napkin flat on the operating table. Inject 3ml of menstrual blood simulating liquid at (23±1)°C into the front two-thirds of the sanitary napkin through the long tube. Record the absorption time (S1) from the time the menstrual blood simulating liquid visually contacts the sanitary napkin to the time the simulating liquid in the long tube is completely absorbed. After three minutes of rest, touch the surface of the sanitary napkin with the back of your hand and record the first touch. Repeat the above action again and record the second absorption time (S2). After three minutes of rest, touch the surface of the sanitary napkin with the back of your hand and record the second touch. Repeat the above action again and record the third absorption time (S3). After three minutes of rest, touch the surface of the sanitary napkin with the back of your hand and record the third touch.

[0053] Back-seepage test: Lay the sanitary napkin flat on the operating table, and quickly inject (23±1)℃ menstrual blood simulation liquid into the front two-thirds of the sanitary napkin through the long tube, inject 3ml of menstrual blood simulation liquid each time, and after a 30s interval, take a 1Kg pressing block to press the filter paper flat on the surface of the sanitary napkin. After 10s of rest, remove the filter paper, record the weight of the filter paper before and after absorbing the back-seepage liquid, and calculate the first back-seepage liquid mass W1; take a new sanitary napkin flat on the operating table, and quickly inject (23±1)℃ menstrual blood simulation liquid into the front two-thirds of the sanitary napkin through the long tube, and inject 3ml of menstrual blood simulation liquid each time. After three minutes of rest, repeat the above actions, and after a 30s interval, Take a 1kg pressing block to press the filter paper flat on the surface of the sanitary napkin. Remove the filter paper after letting it stand for 10 seconds, record the weight of the filter paper before and after absorbing the back-permeate liquid, and calculate the second back-permeate liquid mass W2; then take a new sanitary napkin and lay it flat on the operating table, and quickly inject (23±1)℃ menstrual blood simulation liquid into the sanitary napkin about two-thirds of the front end through the long tube, injecting 3ml of menstrual blood simulation liquid each time. After letting it stand for three minutes, repeat the above steps, and then let it stand for another three minutes, and then repeat the above steps again. After an interval of 30 seconds, take a 1kg pressing block to press the filter paper flat on the surface of the sanitary napkin. Remove the filter paper after letting it stand for 10 seconds, record the weight of the filter paper before and after absorbing the back-permeate liquid, and calculate the third back-permeate liquid mass W3.

[0054] The test results of the above touch, absorption speed and rewet amount are shown in Table 2.

[0055] Table 2 Test results of implementations 1 to 4 and comparative examples 1 to 7

[0056]

[0057]

[0058] In conjunction with the above table, a comparison of Example 1 with Comparative Example 3 revealed that when no anticoagulant was added to the first absorbent layer, under specific test conditions, the third menstrual blood was not completely absorbed. This was because, without the effect of the anticoagulant, the menstrual blood simulation fluid was preferentially absorbed by the first absorbent layer. After the first absorbent layer absorbed 3 ml of the simulation fluid twice, the third simulation fluid had difficulty entering the second absorbent layer, significantly reducing the absorption rate of the simulation fluid. A large amount of the simulation fluid was absorbed by the first absorbent layer and formed clots, resulting in an uneven surface to the touch, which could cause discomfort during use.

[0059] By comparing Example 1 with Comparative Examples 1 and 2, it was found that although there was no defect in the touch due to the lack of the first absorption layer or the lack of the second absorption layer, after absorbing the simulated liquid once, the speed of reabsorption of the simulated liquid decreased within a specific time, and the absorption amount decreased. This shows that compared with Comparative Examples 1 and 2, when the first absorption layer and the second absorption layer are provided at the same time, the second absorption layer cooperates with the first absorption layer, and menstrual blood is more likely to seep into the second absorption layer, thereby increasing the absorption amount, number of absorptions and absorption efficiency.

[0060] Comparing Example 1 with Comparative Examples 4 to 6, it was found that the lack of a hydrophilic additive, the lack of an organic fluorine compound, or the lack of a fatty acid amide all had a certain negative impact on the absorption efficiency of the sanitary napkin.

[0061] By comparing Example 1 with Example 4 and Comparative Example 7, it was found that adding a certain amount of gelatin can effectively improve the absorption efficiency and absorption amount of the sanitary napkin, but excessive gelatin will cause a foreign body sensation on the surface of the sanitary napkin.

[0062] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent replacements and improvements made within the spirit and principles of the present invention should fall within the scope of protection of the present invention.

Claims

1. A multi-layer absorbent sanitary napkin, characterized in that: From bottom to top, it includes a base film, a second absorption layer, a first absorption layer and a skin-friendly layer. The first absorption layer is composed of the following components by weight: 20 to 40 parts of sodium polyacrylate, 2 to 6 parts of anticoagulant, 1 to 2 parts of gelatin, 0.8 to 1.4 parts of fatty acid amide and 0.2 to 0.5 parts of organic fluorine compound; the second absorption layer is composed of the following components by weight: 20 to 40 parts of sodium polyacrylate, 4 to 8 parts of hydrophilic additive, 0.8 to 1.4 parts of fatty acid amide and 0.2 to 0.5 parts of organic fluorine compound.

2. A multi-layer absorbent structure sanitary napkin according to claim 1, characterized in that: The thickness of the first absorption layer is 1 to 2 times that of the second absorption layer.

3. The multi-layer absorbent structure sanitary napkin according to claim 1, characterized in that: The anticoagulant is at least one of sodium citrate, ethylenediaminetetraacetic acid and heparin.

4. The multi-layer absorbent sanitary napkin according to claim 1, characterized in that: The organic fluorine compound is methyl perfluoroisobutyl ether.

5. The multi-layer absorbent sanitary napkin according to claim 1, characterized in that: The hydrophilic additive is polyvinyl alcohol.

6. The multi-layer absorbent sanitary napkin according to claim 1, characterized in that: The preparation method of the first absorption layer includes the following steps: first, sodium polyacrylate, an anticoagulant, a fatty acid amide and an organic fluorine compound are mixed, then added to water, placed in a high-pressure steam cooker, heated at 100-110°C, and mixed to obtain a first mixed solution with a uniform texture; the first mixed solution is inverted into a mold, subjected to electron beam radiation cross-linking treatment to obtain a first mixed copolymer, and the first mixed copolymer is dried, crushed and sieved to obtain an absorption masterbatch of 200-400 μm; gelatin is added to water, stirred and dissolved at 70°C to prepare a 3wt% gelatin aqueous solution, the absorption masterbatch is immersed in the gelatin aqueous solution under negative pressure for 10-20 minutes, then taken out, excess liquid is drained, and then placed at -80°C for freezing, and then freeze-dried to obtain the first absorption layer.

7. The multi-layer absorbent structure sanitary napkin according to claim 1, characterized in that: The preparation method of the second absorption layer includes the following steps: firstly mixing sodium polyacrylate, a hydrophilic additive, a fatty acid amide and an organic fluorine compound, then adding the mixture to water, placing the mixture in a high-pressure steam cooker, heating the mixture at 100-110°C, and mixing the mixture to obtain a second mixed solution with a uniform texture; inverting the second mixed solution into a mold, performing electron beam radiation cross-linking treatment to obtain a second mixed copolymer, and freeze-drying, crushing and screening the second mixed copolymer to obtain the second absorption layer.

8. The method for preparing the multi-layer absorbent sanitary napkin according to any one of claims 1 to 7, comprising the following steps: The base film, the second absorption layer, the first absorption layer and the skin-friendly layer are cut and then placed in a bonding device in order, and the bonding device is used to stick them in sequence to produce a multi-layer absorption structure sanitary napkin.

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