Dispersible degradable sanitary towel and preparation method thereof

Abstract

The invention discloses a degradable sanitary napkin capable of being dispersed and a preparation method thereof, and relates to the technical field of hygienic products, and the sanitary napkin sequentially comprises a surface layer, a first absorption core body, a second absorption core body and a degradable bottom film from top to bottom, the first absorption core body is prepared from the following raw materials in parts by weight: 60 to 70 parts of sodium alginate modified polylactic acid fiber, 40 to 50 parts of bamboo fiber and 1 to 3 parts of fatty acid amide; the second absorption core body is prepared from the following raw materials in parts by weight: 60 to 70 parts of polyethylene glycol modified polylactic acid fiber, 40 to 50 parts of bamboo fiber and 8 to 10 parts of polyvinyl alcohol. The sanitary towel prepared by the invention has good biodegradability.

Description

Technical Field

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

[0002] Currently, the absorbent core of sanitary napkins on the market is usually made of superabsorbent polymer (SAP). SAP is a functional polymer, mainly sodium polyacrylate, which can absorb liquids dozens of times its own weight and lock them in firmly. However, the molecular structure of this type of SAP is very stable and it is difficult for microorganisms to decompose it in the natural environment, so its degradation is very poor. Summary of the Invention

[0003] To address the shortcomings of the existing technology, one objective of this invention is to provide a flushable biodegradable sanitary napkin that uses biodegradable polylactic acid as the main material of the absorbent core, exhibiting good biodegradability. Another objective is to provide a method for preparing a flushable biodegradable sanitary napkin that improves the absorbency of polylactic acid while ensuring the biodegradability of the absorbent core, thereby enhancing the absorbency of the sanitary napkin.

[0004] One of the objectives of this invention is achieved through the following technical solution:

[0005] A flushable biodegradable sanitary napkin comprises, from top to bottom, a surface layer, a first absorbent core, a second absorbent core, and a biodegradable bottom film. The first absorbent core comprises the following raw materials in parts by weight: 60-70 parts of sodium alginate-modified polylactic acid fiber, 40-50 parts of bamboo fiber, and 1-3 parts of fatty acid amide. The second absorbent core comprises the following raw materials in parts by weight: 60-70 parts of polyethylene glycol-modified polylactic acid fiber, 40-50 parts of bamboo fiber, and 8-10 parts of polyvinyl alcohol.

[0006] As a preferred embodiment, the preparation method of sodium alginate modified polylactic acid fiber includes the following steps: dissolving sodium alginate in water to obtain sodium alginate aqueous solution, adding polylactic acid fiber to sodium alginate aqueous solution, ultrasonically soaking for 30-40 minutes, taking out the soaked polylactic acid fiber, removing excess liquid from the polylactic acid fiber, adding it to calcium chloride aqueous solution, reacting for 30-60 minutes, taking it out, removing excess liquid from the polylactic acid fiber, and freeze-drying the polylactic acid fiber to obtain sodium alginate modified polylactic acid fiber.

[0007] Using the above method, sodium alginate is attached to polylactic acid fibers via hydrogen bonds, etc. On the one hand, the preparation method is simple; on the other hand, because the chemical bonds are not strong, the sodium alginate attached to the polylactic acid fibers may detach from the polylactic acid fibers and dissolve in water when it comes into contact with water, leaving pores in the first absorbent core.

[0008] As a preferred option, the concentration of sodium alginate aqueous solution is 2-4 w / v, and the concentration of calcium chloride aqueous solution is 3-5 w / v.

[0009] As a preferred embodiment, the preparation method of polyethylene glycol modified polylactic acid fiber includes the following steps: taking polylactic acid, polyethylene glycol, L-lactide and catalyst, dissolving polyethylene glycol, L-lactide and catalyst in a solvent, stirring and reacting at 150-170℃ for 1-2 hours under nitrogen protection to obtain a prepolymer, subjecting the prepolymer to methyl acetate dissolution treatment and methyl tert-butyl ether stirring precipitation treatment in sequence, drying the obtained precipitate to obtain polyethylene glycol modified polylactic acid, and then preparing polyethylene glycol modified polylactic acid fiber.

[0010] As a preferred embodiment, the mass ratio of polylactic acid to polyethylene glycol is 1:2-4, and the mass ratio of polyethylene glycol to L-lactide is 1:2-4.

[0011] As a preferred option, the solvent is xylene or toluene, and the concentration of polyethylene glycol in the prepolymer is 5-8 w / v.

[0012] As a preferred option, the catalyst is stannous octoate, and the molar ratio of polyethylene glycol to catalyst is 1:0.1-0.2.

[0013] As a preferred embodiment, the volume of methyl acetate is 1-2 times the mass of the prepolymer, and the volume of methyl tert-butyl ether is 10-15 times the volume of methyl acetate.

[0014] As a preferred option, the obtained precipitate is dried at a temperature of 60-70℃.

[0015] The second objective of this invention is achieved by the following technical solution:

[0016] A method for preparing a flushable biodegradable sanitary napkin involves uniformly mixing sodium alginate-modified polylactic acid fiber, bamboo fiber, and fatty acid amide to obtain a first absorbent core; uniformly mixing polyethylene glycol-modified polylactic acid fiber, bamboo fiber, and polyvinyl alcohol to obtain a second absorbent core; and sequentially placing the bottom film, the second absorbent core, the first absorbent core, and the top layer onto an adhesive bonding device, which then bonds them together to obtain a flushable biodegradable sanitary napkin.

[0017] The beneficial effects of this invention are:

[0018] (1) Polylactic acid is a polyester polymer obtained by polymerization of lactic acid. It has good thermal stability and can be made into polylactic acid fiber by extrusion, spinning and other processes. Polylactic acid fiber has good biodegradability, biocompatibility and mechanical properties. Although polylactic acid fiber has a certain water absorption, it still has the problem of insufficient hydrophilicity and water absorption when applied in the field of sanitary products. In order to further increase the water absorption of sanitary napkins, bamboo fiber is added to the absorbent core. Bamboo fiber is a natural cellulose with good biodegradability. Its moisture absorption and breathability are much higher than cotton, and its water absorption is excellent.

[0019] (2) The absorbent core consists of two layers. The first absorbent core and the second absorbent core are cut and pasted separately, making them easier to flush away. At the same time, the first absorbent core is on top of the second absorbent core. The fatty acid amide has a lubricating and anti-sticking effect. The addition of fatty acid amide to the first absorbent core can prevent a large amount of menstrual blood from staying in the first absorbent core, providing favorable conditions for menstrual blood to seep into the second absorbent core and increasing the absorbency of the sanitary napkin.

[0020] (3) Sodium alginate is a natural polysaccharide that is easily soluble in water, forming a viscous colloidal solution. It is non-toxic and has good biocompatibility. Attaching sodium alginate to polylactic acid fibers can increase the hydrophilicity and absorbency of the polylactic acid fibers. Moreover, since menstrual blood contains a large amount of water, when the menstrual blood flows to the first absorbent core, the water in the menstrual blood can dissolve some of the sodium alginate. The sodium alginate dissolves in the menstrual blood and seeps down with the menstrual blood, leaving more pores on the first absorbent core. These pores can provide space for the next absorption of menstrual blood, so that the sanitary napkin can absorb multiple times quickly.

[0021] (4) Polyethylene glycol is a high molecular polymer that is non-irritating and has good water solubility. Adding polyethylene glycol to polylactic acid fiber can increase the hydrophilicity and absorbency of polylactic acid fiber. Polyethylene glycol is far less biocompatible and skin-friendly than sodium alginate, but its price is far lower than that of sodium alginate. Therefore, the first absorption layer close to the skin uses polylactic acid fiber modified with sodium alginate, while the second absorption layer below the first absorption layer uses polylactic acid fiber modified with polyethylene glycol. Detailed Implementation

[0022] To make the technical problems solved by the invention, the technical solutions and the beneficial effects clearer, the invention will be further explained below in conjunction with embodiments and comparative examples.

[0023] Example 1

[0024] This embodiment provides a flushable biodegradable sanitary napkin, which, from top to bottom, comprises a top layer, a first absorbent core, a second absorbent core, and a biodegradable bottom film. The first absorbent core comprises the following raw materials in parts by weight: 60 parts of sodium alginate-modified polylactic acid fiber, 50 parts of bamboo fiber, and 2 parts of fatty acid amide. The second absorbent core comprises the following raw materials in parts by weight: 60 parts of polyethylene glycol-modified polylactic acid fiber, 50 parts of bamboo fiber, and 9 parts of polyvinyl alcohol.

[0025] Example 2

[0026] This embodiment provides a flushable biodegradable sanitary napkin, which, from top to bottom, comprises a top layer, a first absorbent core, a second absorbent core, and a biodegradable bottom film. The first absorbent core comprises the following raw materials in parts by weight: 70 parts of sodium alginate-modified polylactic acid fiber, 40 parts of bamboo fiber, and 1 part of fatty acid amide. The second absorbent core comprises the following raw materials in parts by weight: 70 parts of polyethylene glycol-modified polylactic acid fiber, 40 parts of bamboo fiber, and 8 parts of polyvinyl alcohol.

[0027] Example 3

[0028] This embodiment provides a flushable biodegradable sanitary napkin, which, from top to bottom, comprises a top layer, a first absorbent core, a second absorbent core, and a biodegradable bottom film. The first absorbent core comprises the following raw materials in parts by weight: 65 parts of sodium alginate-modified polylactic acid fiber, 45 parts of bamboo fiber, and 3 parts of fatty acid amide. The second absorbent core comprises the following raw materials in parts by weight: 65 parts of polyethylene glycol-modified polylactic acid fiber, 45 parts of bamboo fiber, and 10 parts of polyvinyl alcohol.

[0029] Example 4

[0030] This embodiment provides a flushable biodegradable sanitary napkin, which, from top to bottom, comprises a top layer, a first absorbent core, a second absorbent core, and a biodegradable bottom film. The first absorbent core comprises the following raw materials in parts by weight: 65 parts of sodium alginate-modified polylactic acid fiber, 45 parts of bamboo fiber, and 2 parts of fatty acid amide. The second absorbent core comprises the following raw materials in parts by weight: 65 parts of polyethylene glycol-modified polylactic acid fiber, 45 parts of bamboo fiber, and 9 parts of polyvinyl alcohol.

[0031] In Examples 1-4, the preparation method of sodium alginate modified polylactic acid fiber is as follows: sodium alginate is dissolved in water to obtain a sodium alginate aqueous solution with a concentration of 4w / v%. Polylactic acid fiber is added to the sodium alginate aqueous solution, and the sodium alginate aqueous solution is sufficient to cover the polylactic acid fiber. The fiber is ultrasonically soaked for 40 minutes. After soaking, the polylactic acid fiber is taken out, and the excess liquid on the polylactic acid fiber is drained. Then, it is added to a calcium chloride aqueous solution with a concentration of 4w / v. After reacting for 60 minutes, the fiber is taken out, and the excess liquid on the polylactic acid fiber is drained. The polylactic acid fiber is then freeze-dried to obtain sodium alginate modified polylactic acid fiber.

[0032] In Examples 1-4, the preparation method of polyethylene glycol modified polylactic acid (PLA) fiber is as follows: PLA, polyethylene glycol, and stannous octoate are taken, with a mass ratio of PLA to PLA of 1:3, a molar ratio of PLA to catalyst of 1:0.1, and a mass ratio of PLA to L-lactide of 1:3. PLA, L-lactide, and stannous octoate are dissolved in xylene, and the mixture is stirred and reacted at 150°C for 1 hour under nitrogen protection to obtain a prepolymer. The prepolymer is then subjected to methyl acetate dissolution treatment and methyl tert-butyl ether (MTBE) precipitation treatment, with the volume of methyl acetate being twice the mass of the prepolymer and the volume of MTBE being ten times the volume of methyl acetate. The resulting precipitate is dried at 60°C for 2 hours to obtain PLA modified with PLA. The PLA modified with PLA is then used to prepare PLA fiber.

[0033] The preparation method of the flushable biodegradable sanitary napkins in Examples 1-4 is as follows: sodium alginate-modified polylactic acid fiber, bamboo fiber and fatty acid amide are mixed evenly and pressed to obtain a first absorbent core; polyethylene glycol-modified polylactic acid fiber, bamboo fiber and polyvinyl alcohol are mixed evenly and pressed to obtain a second absorbent core; the bottom film, the second absorbent core, the first absorbent core and the top layer are placed in sequence on an adhesive bonding device and bonded together by the adhesive bonding device to obtain a flushable biodegradable sanitary napkin.

[0034] Comparative Example 1

[0035] Compared to Example 1, the first absorbent core of this comparative example does not include bamboo fiber.

[0036] Comparative Example 2

[0037] Compared with Example 1, the second absorbent core of this comparative example does not include bamboo fiber.

[0038] Comparative Example 3

[0039] Compared to Example 1, the first absorber core of this comparative example does not contain fatty acid amides.

[0040] Comparative Example 4

[0041] Compared to Example 1, the second absorber core in this comparative example does not contain polyvinyl alcohol.

[0042] Comparative Example 5

[0043] Compared with Example 1, this comparative example uses polylactic acid fiber instead of sodium alginate modified polylactic acid fiber.

[0044] Comparative Example 6

[0045] Compared with Example 1, this comparative example uses polylactic acid fiber instead of polyethylene glycol-modified polylactic acid fiber.

[0046] Performance tests were conducted on the sanitary napkins of Examples 1-4 and Comparative Examples 1-6.

[0047] Absorption rate test: Lay the sanitary napkin flat on the operating table, and inject (23±1)℃ menstrual blood simulation solution into the sanitary napkin about two-thirds of the way from the front end through the long tube. Inject 3ml of menstrual blood simulation solution each time, and record the absorption time S1 from when the menstrual blood simulation solution comes into contact with the sanitary napkin to when the simulation solution in the long tube is completely absorbed. After resting for three minutes, repeat the above action and record the second absorption time S2. After resting for three minutes, repeat the above action again and record the third absorption time S3.

[0048] Degradability test: The sanitary napkin was placed in a Bacillus subtilis environment, and the amount of carbon dioxide produced by the decomposition of the sanitary napkin was tested on the 60th day. The biodegradability rate of the sanitary napkin was calculated from the amount of carbon dioxide.

[0049] The test results for absorption rate and degradation are shown in Table 1.

[0050] Table 1 Performance test results of Examples 1-4 and Comparative Examples 1-6

[0051]

[0052] As shown in Table 1, the sanitary napkin prepared by the present invention has good biodegradability and menstrual blood absorbency. Comparing Example 1 with Comparative Examples 1 and 2, it can be seen that the lack of bamboo fiber in the absorbent core affects the absorption speed and amount of the sanitary napkin in multiple absorptions. Comparing Example 1 with Comparative Examples 3 and 4, it can be seen that the lack of fatty acid amide in the first absorbent core or the lack of polyvinyl alcohol in the second absorbent core will affect the absorption speed of the sanitary napkin in multiple absorptions. Comparing Example 1 with Comparative Examples 5 and 6, it can be seen that the absorption performance of unmodified polylactic acid fiber is much lower than that of modified polylactic acid fiber.

[0053] 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 flushable biodegradable sanitary napkin, characterized in that, From top to bottom, the structure comprises a surface layer, a first absorbent core, a second absorbent core, and a biodegradable bottom film. The first absorbent core comprises the following raw materials in parts by weight: 60-70 parts of sodium alginate-modified polylactic acid fiber, 40-50 parts of bamboo fiber, and 1-3 parts of fatty acid amide. The second absorbent core comprises the following raw materials in parts by weight: 60-70 parts of polyethylene glycol-modified polylactic acid fiber, 40-50 parts of bamboo fiber, and 8-10 parts of polyvinyl alcohol.

2. The flushable biodegradable sanitary napkin according to claim 1, characterized in that, The preparation method of sodium alginate modified polylactic acid fiber includes the following steps: dissolving sodium alginate in water to obtain sodium alginate aqueous solution, adding polylactic acid fiber to sodium alginate aqueous solution, ultrasonically soaking for 30-40 minutes, taking out the soaked polylactic acid fiber, removing excess liquid from the polylactic acid fiber, adding it to calcium chloride aqueous solution, reacting for 30-60 minutes, taking it out, removing excess liquid from the polylactic acid fiber, and freeze-drying the polylactic acid fiber to obtain sodium alginate modified polylactic acid fiber.

3. The flushable biodegradable sanitary napkin according to claim 2, characterized in that, The concentration of sodium alginate aqueous solution is 2-4 w / v, and the concentration of calcium chloride aqueous solution is 3-5 w / v.

4. The flushable biodegradable sanitary napkin according to claim 1, characterized in that, The preparation method of polyethylene glycol modified polylactic acid fiber includes the following steps: polylactic acid, polyethylene glycol, L-lactide and catalyst are taken, polyethylene glycol, L-lactide and catalyst are dissolved in solvent, and under nitrogen protection, the mixture is stirred and reacted at 150-170℃ for 1-2 hours to obtain a prepolymer. The prepolymer is subjected to methyl acetate dissolution treatment and methyl tert-butyl ether stirring precipitation treatment in sequence. The obtained precipitate is dried to obtain polyethylene glycol modified polylactic acid, and then the polyethylene glycol modified polylactic acid is made into polyethylene glycol modified polylactic acid fiber.

5. A flushable biodegradable sanitary napkin according to claim 4, characterized in that, The mass ratio of polylactic acid to polyethylene glycol is 1:2-4, and the mass ratio of polyethylene glycol to L-lactide is 1:2-4.

6. The flushable biodegradable sanitary napkin according to claim 4, characterized in that, The solvent is xylene or toluene, and the concentration of polyethylene glycol in the prepolymer is 5-8 w / v.

7. A flushable biodegradable sanitary napkin according to claim 4, characterized in that, The catalyst is stannous octoate, and the molar ratio of polyethylene glycol to catalyst is 1:0.1-0.

2.

8. A flushable biodegradable sanitary napkin according to claim 4, characterized in that, The volume of methyl acetate is 1-2 times the mass of the prepolymer, and the volume of methyl tert-butyl ether is 10-15 times the volume of methyl acetate.

9. A flushable biodegradable sanitary napkin according to claim 4, characterized in that, The obtained precipitate was dried at a temperature of 60-70℃.

10. A method for preparing a flushable biodegradable sanitary napkin as described in any one of claims 1-9, characterized in that, Sodium alginate-modified polylactic acid fiber, bamboo fiber, and fatty acid amide are mixed evenly to obtain the first absorbent core; polyethylene glycol-modified polylactic acid fiber, bamboo fiber, and polyvinyl alcohol are mixed evenly to obtain the second absorbent core; the bottom film, the second absorbent core, the first absorbent core, and the top layer are placed in sequence on an adhesive bonding device and bonded together sequentially by the adhesive bonding device to obtain a flushable biodegradable sanitary napkin.

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