Sanitary pad structure and preparation method therefor

Abstract

A sanitary pad, comprising: a fabric layer, an absorbent core body, and a water-repellent layer, wherein the absorbent core body comprises a star-shaped modified acrylic resin, and the star-shaped modified acrylic resin comprises: a star-shaped acrylic acid monomer, acrylate, acrylamide, and modified silica particles. The absorbent core body of the sanitary pad structure provided by the present invention can keep water molecules inside a star-shaped acrylate copolymer, preventing loss of water molecules and keeping the sanitary pad dry and comfortable. The core body is highly absorbent, absorbs water rapidly, and retains water effectively.

Description

A sanitary napkin structure and its preparation method Technical Field

[0001] This invention relates to the field of hygiene products technology, and in particular to a sanitary napkin structure and its preparation method. Background Technology

[0002] Sanitary napkins, as an essential product for women during menstruation, are designed to improve women's quality of life during menstruation. After years of development and improvement, they can now meet women's needs very well.

[0003] However, traditional sanitary napkins typically use a mixture of fluff pulp and superabsorbent polymer (SAP) as the absorbent core. While this combination improves absorbency to some extent, problems such as slow absorption, insufficient absorbency, and backflow can still occur during use. These issues not only affect the effectiveness of the sanitary napkin but may also cause discomfort or problems for women's menstrual health.

[0004] In conclusion, there is an urgent need to develop a new technical solution to address the problems existing in the current technology and meet the development needs of the current market. Summary of the Invention

[0005] Based on this, the present invention provides a sanitary napkin structure and its preparation method. The absorbent core of the sanitary napkin structure provided by the present invention is made from a mixed emulsion of star-shaped modified acrylic resin, acrylate, crosslinking agent, and other components. The modified acrylic resin is made from star-shaped acrylic monomer, acrylic-modified silica particles 1, and modified silica particles 2, and has strong water absorption capacity, fast water absorption rate, and excellent water retention performance.

[0006] One object of the present invention is to provide a sanitary napkin structure comprising, from bottom to top, a water-repellent layer, an absorbent core, and a fabric layer, wherein the absorbent core structure is as follows:

[0007] A thin film structure with permeable pores;

[0008] The raw material emulsion with the thin film structure includes the following components:

[0009] Star-shaped modified acrylic resin, acrylate, crosslinking agent, photoinitiator, initiator, additives, and solvent;

[0010] The raw materials for the star-shaped modified acrylic resin include:

[0011] The product comprises star-shaped acrylic monomers, acrylates, acrylamide, crosslinking agents, initiators, additives, solvents, and acrylic-modified silica particles 1 and modified silica particles 2.

[0012] The modified silica particles 1 are hydroxylated silica, a product of partial grafting with acrylic acid and partial grafting with oleic acid.

[0013] The modified silica particles 2 are hydroxylated silica, partially grafted with acrylic acid and partially grafted with alkyl acid.

[0014] Further, the mass ratio of the star-shaped acrylic monomer, acrylate, acrylamide, crosslinking agent, initiator, auxiliary agent, solvent, modified silica particles 1 and modified silica particles 2 is (20-40):(5-15):(5-15):(1-5):(0.1-2):(1-5):(40-100):(5-10):(5-10).

[0015] Furthermore, the pore size of the permeation pore is 60-130 μm.

[0016] Furthermore, the star-shaped acrylic monomer is trimethylolpropane trimethacrylate.

[0017] Furthermore, the crosslinking agent is N,N-methylenebisacrylamide.

[0018] Furthermore, the photoinitiator is 2-hydroxy-2-methyl-1-phenyl-1-propanone.

[0019] Furthermore, the initiator is selected from one or more of ammonium persulfate, sodium persulfate, potassium persulfate, and azo initiators.

[0020] Furthermore, the additive is selected from one or more of emulsifiers, surfactants, leveling agents, accelerators, or film-forming aids.

[0021] Furthermore, in the modified silica particles 1, the ratio of acrylate to oleic acid is 1:0.1-0.3.

[0022] Furthermore, in the modified silica particles 2, the ratio of acrylate to alkyl acid is 1:1-3.

[0023] Another object of the present invention is to provide a method for preparing the above-mentioned sanitary napkin structure, including a method for preparing an absorbent core, the method for preparing the absorbent core comprising the following steps:

[0024] S1. Add silica to strong acid and hydrogen peroxide for treatment to obtain hydroxylated silica 1; mix the hydroxylated silica 1 with acrylic acid and oleic acid, and react with ultrasonic heating to obtain modified silica particles 1.

[0025] S2. Add silica to strong acid and hydrogen peroxide for hydroxylation treatment to obtain hydroxylated silica 2; blend the hydroxylated silica 2 with acrylic acid and alkyl acid, and react with ultrasonic heating to obtain modified silica particles 2.

[0026] S3. The star-shaped acrylic monomer, acrylate, acrylamide, crosslinking agent, initiator, additive, solvent, modified silica particles 1 and modified silica particles 2 are blended, heated and reacted under an inert gas atmosphere, and purified to obtain a star-shaped modified acrylic resin.

[0027] S4. The star-shaped modified acrylic resin, acrylate, crosslinking agent, photoinitiator, initiator, additives, and solvent are blended to obtain an emulsion;

[0028] S5. The emulsion is coated onto the surface of the fabric, reacted under light, and then treated with steam to dehydrate and dry, thereby obtaining the absorbent core.

[0029] Furthermore, in step S1, the temperature of the heating reaction is 60-80℃; the heating reaction time is 8-12h.

[0030] Furthermore, in step S2, the temperature of the heating reaction is 60-80℃; the heating reaction time is 8-12h.

[0031] Furthermore, in step S3, the heating temperature is 60-100℃.

[0032] Furthermore, in step S5, the thickness of the emulsion coating is 0.5-2 mm.

[0033] The present invention has the following beneficial effects:

[0034] The absorbent core of the sanitary napkin structure provided by this invention is made from a mixed emulsion of star-shaped modified acrylic resin, acrylate, crosslinking agent, and other components. The modified acrylic resin is made from star-shaped acrylic monomer, acrylic and fatty acid-modified silica particles 1, and modified silica particles 2. This invention first hydroxylates silica to enhance its surface group activity, then reacts it with acrylic acid and oleic acid to obtain modified silica particles 1 with unsaturated double bonds on their surface. Using the same treatment method, modified silica particles 2 with unsaturated double bonds and alkyl chains are obtained. Then, using the star-shaped acrylic monomer as the core structure, it is copolymerized with acrylate, acrylamide, and modified silica particles 1 and 2 to obtain a star-shaped modified acrylic resin. This star-shaped modified acrylic resin possesses strong water absorption capacity and a fast absorption rate. On one hand, its molecules contain abundant hydrophilic groups such as ester and amide groups, which can form hydrogen bonds with water molecules, thereby attracting and fixing a large number of water molecules and quickly absorbing large amounts of menstrual blood. On the other hand, its star-shaped molecular structure increases the contact area between the polymer and water molecules, accelerating the adsorption and diffusion process of water molecules, allowing the sanitary napkin to absorb menstrual blood rapidly after contact, reducing the possibility of blood accumulating on the absorbent core surface or overflowing. In addition, through copolymerization, the modified silica particles 1 and 2 are uniformly dispersed in the star-shaped acrylic matrix, serving as spatial crosslinking sites to form a stable network structure. This results in a star-shaped acrylate copolymer with an extremely high specific surface area, thereby increasing its water absorption rate. At the same time, the stable network structure can extend the diffusion path of water molecules from the inside of the resin to the outside, thus retaining water molecules inside the star-shaped acrylate copolymer, preventing water molecule loss, and keeping the sanitary napkin dry and comfortable. Detailed Implementation

[0035] To more clearly illustrate the technical solution of the present invention, the following embodiments are provided. Unless otherwise stated, the raw materials, reactions, and post-processing methods appearing in the embodiments are all commercially available raw materials and technical methods well known to those skilled in the art.

[0036] The terms "preferred," "more preferably," and "more suitable" used in this invention refer to embodiments of the invention that provide certain beneficial effects under certain circumstances. However, other embodiments may also be preferred under the same or other circumstances. Furthermore, the description of one or more preferred embodiments does not imply that other embodiments are unavailable, nor is it intended to exclude other embodiments from the scope of this invention.

[0037] It should be understood that, except in any operational instance or otherwise indicated, the amounts or all figures representing ingredients used, for example, in the specification and claims, should be understood to be modified by the term "about" in all cases. Therefore, unless otherwise stated, the numerical parameters set forth in the following specification and appended claims are approximate values ​​varying according to the desired performance to be obtained according to the invention.

[0038] The azobisisobutylamidine hydrochloride used in the embodiments and comparative examples of this invention is V50, manufactured by Hubei Shixing Chemical Co., Ltd.

[0039] In the embodiments of this invention, "parts" refers to parts by mass.

[0040] Example 1

[0041] A sanitary napkin structure, from bottom to top, includes a water-repellent layer, an absorbent core, and a fabric layer, wherein the absorbent core structure is as follows:

[0042] A thin film structure with permeable pores having a pore size of 60-130 μm;

[0043] The raw material emulsion with the thin film structure includes the following components:

[0044] The mixture consists of 10 parts of star-shaped modified acrylic resin, 50 parts of isobutyl acrylate, 15 parts of N,N-methylenebisacrylamide, 1 part of 2-hydroxy-2-methyl-1-phenyl-1-propanone, 1 part of azobisisobutylamidine hydrochloride, 5 parts of dioctadecyl dimethylammonium bromide, and 200 parts of deionized water.

[0045] The raw materials for the star-shaped modified acrylic resin include:

[0046] 30 parts of trimethylolpropane trimethacrylate, 10 parts of sodium acrylate, 8 parts of acrylamide, 1 part of N,N-methylenebisacrylamide, 1 part of azobisisobutylammonium hydrochloride, 2 parts of dioctadecyl dimethylammonium bromide, 80 parts of deionized water, and 18 parts of acrylic acid-modified silica particles and 28 parts of modified silica particles.

[0047] The modified silica particles 1 are hydroxylated silica, a product of partial grafting with acrylic acid and partial grafting with oleic acid.

[0048] The modified silica particles 2 are hydroxylated silica, partially grafted with acrylic acid and partially grafted with lauric acid.

[0049] The preparation method of the above-mentioned absorber core includes the following steps:

[0050] S1. Add silica to a mixed solution of concentrated sulfuric acid and hydrogen peroxide (mass ratio of concentrated sulfuric acid to hydrogen peroxide m:m = 7:3, concentration of hydrogen peroxide is 30%), react at 80°C for 1 h, wash away unreacted concentrated sulfuric acid and hydrogen peroxide to obtain hydroxylated silica 1; use ethanol as solvent, mix the hydroxylated silica 1, acrylic acid and oleic acid, sonicate at 70°C for 10 h, then filter, wash and dry to obtain modified silica particles 1;

[0051] Wherein, the mass ratio of silicon dioxide, acrylic acid and oleic acid is m:m:m = 1:5:1;

[0052] S2. Add silica to a mixed solution of concentrated sulfuric acid and hydrogen peroxide (mass ratio of concentrated sulfuric acid to hydrogen peroxide m:m = 7:3, concentration of hydrogen peroxide is 30%), react at 80°C for 1 h, wash away unreacted concentrated sulfuric acid and hydrogen peroxide to obtain hydroxylated silica 2; use ethanol as solvent, mix the hydroxylated silica 2, acrylic acid and lauric acid, sonicate at 70°C for 10 h, then filter, wash and dry to obtain modified silica particles 2;

[0053] Wherein, the mass ratio of silicon dioxide, acrylic acid and lauric acid is m:m:m = 1:5:5;

[0054] S3. According to the above mass proportions, trimethylolpropane trimethacrylate, sodium acrylate, acrylamide, N,N-methylenebisacrylamide, azobisisobutylammonium hydrochloride, dioctadecyl dimethylammonium bromide, deionized water, and acrylic acid-modified silica particles 1 and modified silica particles 2 are blended and reacted at 70°C for 2 hours under a nitrogen atmosphere. After filtration, washing and drying, a star-shaped modified acrylic resin is obtained.

[0055] S4. The star-shaped modified acrylic resin, isobutyl acrylate, N,N-methylenebisacrylamide, 2-hydroxy-2-methyl-1-phenyl-1-propanone, azobisisobutylamidine hydrochloride, dioctadecyl dimethylammonium bromide and deionized water are blended to obtain an emulsion.

[0056] S5. The emulsion is coated onto the upper and lower surfaces of the nonwoven fabric, each with a thickness of 1.5 mm, and then subjected to a wavelength of 450 nm and an intensity of 50 mW / cm. 2 The absorber core is obtained by irradiating it with light for 120 seconds, then placing it in a steam tunnel oven for 5 minutes to cure. After dehydration, drying, and slitting, the absorber core is obtained.

[0057] Example 2

[0058] A sanitary napkin structure, from bottom to top, includes a water-repellent layer, an absorbent core, and a fabric layer, wherein the absorbent core structure is as follows:

[0059] A thin film structure with permeable pores having a pore size of 60-130 μm;

[0060] The raw material emulsion with the thin film structure includes the following components:

[0061] The mixture consists of 10 parts of star-shaped modified acrylic resin, 55 parts of isobutyl acrylate, 16 parts of N,N-methylenebisacrylamide, 1 part of 2-hydroxy-2-methyl-1-phenyl-1-propanone, 1 part of azobisisobutylammonium hydrochloride, 5 parts of dioctadecyl dimethylammonium bromide, and 250 parts of deionized water.

[0062] The raw materials for the star-shaped modified acrylic resin include:

[0063] 25 parts of trimethylolpropane trimethacrylate, 8 parts of sodium acrylate, 7 parts of acrylamide, 1 part of N,N-methylenebisacrylamide, 1 part of azobisisobutylammonium hydrochloride, 2 parts of dioctadecyl dimethylammonium bromide, 70 parts of deionized water, and 16 parts of acrylic acid-modified silica particles and 27 parts of modified silica particles.

[0064] The modified silica particles 1 are hydroxylated silica, a product of partial grafting with acrylic acid and partial grafting with oleic acid.

[0065] The modified silica particles 2 are hydroxylated silica, partially grafted with acrylic acid and partially grafted with lauric acid.

[0066] The preparation method of the above-mentioned absorber core is the same as that in Example 1.

[0067] Example 3

[0068] A sanitary napkin structure, from bottom to top, includes a water-repellent layer, an absorbent core, and a fabric layer, wherein the absorbent core structure is as follows:

[0069] A thin film structure with permeable pores having a pore size of 60-130 μm;

[0070] The raw material emulsion with the thin film structure includes the following components:

[0071] The mixture consists of 12 parts of star-shaped modified acrylic resin, 60 parts of isobutyl acrylate, 20 parts of N,N-methylenebisacrylamide, 1 part of 2-hydroxy-2-methyl-1-phenyl-1-propanone, 1 part of azobisisobutylamidine hydrochloride, 5 parts of dioctadecyl dimethylammonium bromide, and 250 parts of deionized water.

[0072] The raw materials for the star-shaped modified acrylic resin include:

[0073] 35 parts of trimethylolpropane trimethacrylate, 12 parts of sodium acrylate, 10 parts of acrylamide, 1 part of N,N-methylenebisacrylamide, 1 part of azobisisobutylammonium hydrochloride, 2 parts of dioctadecyl dimethylammonium bromide, 90 parts of deionized water, and 110 parts of acrylic acid-modified silica particles and 29 parts of modified silica particles.

[0074] The modified silica particles 1 are hydroxylated silica, a product of partial grafting with acrylic acid and partial grafting with oleic acid.

[0075] The modified silica particles 2 are hydroxylated silica, partially grafted with acrylic acid and partially grafted with lauric acid.

[0076] The preparation method of the above-mentioned absorber core is the same as that in Example 1.

[0077] Comparative Example 1

[0078] A sanitary napkin structure, the difference between this comparative example and Example 1 is that: in the preparation method of the absorbent core, the modified silica particles 1 are replaced with unmodified silica, and the other components and preparation methods are the same as in Example 1.

[0079] Comparative Example 2

[0080] A sanitary napkin structure, the difference between this comparative example and Example 1 is that in the preparation method of the absorbent core, trimethylolpropane trimethacrylate is replaced with isobutyl acrylate, while other components and preparation methods are the same as in Example 1.

[0081] Test case

[0082] Performance comparison tests were conducted on Examples 1-3 and Comparative Examples 1-2.

[0083] Test method: The water absorption rate and blood absorption rate were tested according to GB / T14207-2008.

[0084] The test results are shown in Table 1.

[0085] Table 1 Absorption performance test results

[0086]

[0087] Table 1 shows that the absorbent core prepared by the star-shaped modified acrylic resin, acrylate, crosslinking agent, and other components of the present invention exhibits excellent liquid absorption capacity. Its permeation time, reabsorption amount, and water absorption are significantly better than those of Comparative Examples 1-2. In Comparative Example 1, because unmodified silica was used instead of modified silica particles 1, the prepared star-shaped acrylate copolymer struggled to form a more three-dimensional and dense microporous structure, and its specific surface area was relatively low. Therefore, the absorption capacity of the prepared absorbent core was significantly reduced, its water retention performance was unsatisfactory, and the reabsorption amount of artificial menstrual blood was large. Comparative Example 2 used isobutyl acrylate instead of trimethylolpropane trimethacrylate. After modification, its molecules contained fewer hydrophilic groups, resulting in weaker water absorption capacity. Furthermore, it lacked a star-shaped structure, leading to a smaller contact area with water molecules. Therefore, the performance of the prepared absorbent core product was greatly reduced.

[0088] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from the spirit or essential characteristics of the invention. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, it is intended that all variations falling within the meaning and scope of equivalents of the claims be included within the present invention.

[0089] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A sanitary napkin, said sanitary napkin comprising: Fabric layer; Absorbing core; and water-repellent layer; The absorbent core comprises a star-shaped modified acrylic resin, wherein the star-shaped modified acrylic resin comprises: It consists of star-shaped acrylic monomers, acrylates, acrylamides, and modified silica particles.

2. The sanitary napkin according to claim 1, wherein the modified silica particles comprise first modified silica particles and second modified silica particles.

3. The sanitary napkin according to claim 2, wherein the absorbent core comprises star-shaped acrylic monomers, acrylates, acrylamide, first modified silica particles and second modified silica particles in a mass ratio of (20-40):(5-15):(5-15):(5-10):(5-10).

4. The sanitary napkin according to any one of claims 1-3, wherein the absorbent core includes permeation pores, wherein the diameter of the permeation pores is from 60 μm to 130 μm.

5. The sanitary napkin according to any one of claims 1-4, wherein the star-shaped acrylic monomer is trimethylolpropane trimethacrylate.

6. The sanitary napkin according to any one of claims 2-5, wherein the first modified silica particles are a product of hydroxylated silica, partially grafted acrylic acid, and partially grafted oleic acid.

7. The sanitary napkin according to claim 6, wherein the first modified silica particles comprise acrylic acid and partially grafted oleic acid in a ratio of 1:0.1-0.

3.

8. The sanitary napkin according to any one of claims 2-7, wherein the second modified silica particles are a product of hydroxylated silica, partially grafted acrylic acid, and partially grafted alkyl acid.

9. The sanitary napkin according to claim 8, wherein the second modified silica particles comprise acrylic acid and partially grafted alkyl acid in a ratio of 1:1-3.

10. A method for preparing an absorber core according to any one of claims 1-9, wherein the method comprises the following steps: a. Provide modified silica particles; b. Blend star-shaped acrylic monomers, acrylates, acrylamide and the modified silica particles, and heat to obtain a star-shaped modified acrylic resin; c. The star-shaped modified acrylic resin, acrylate, additives and solvent are blended to obtain an emulsion; d. Deposit the emulsion onto the surface; e. Expose the emulsion to light; f. Place the emulsion into a steam tunnel furnace; as well as g. Dehydrate and dry the emulsion to obtain the absorbent core.

11. The method according to claim 10, wherein in step (b), the heating temperature is 60-100°C.

12. The method according to any one of claims 10-11, wherein the additive is selected from one or more of emulsifiers, surfactants, leveling agents, accelerators or film-forming aids.

13. The method according to any one of claims 10-12, wherein step (c) further comprises an initiator.

14. The method of claim 13, wherein the initiator is one or more of ammonium persulfate, sodium persulfate, potassium persulfate, or an azo initiator.

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