Super-absorption paper diaper as well as preparation method and application thereof

Abstract

The invention relates to a super-absorbent paper diaper and a preparation method and application thereof.The super-absorbent paper diaper comprises a bottom film, a core layer, a surface layer and elastic side seals and is characterized in that the core layer is prepared from, by weight, 50-60 parts of acrylic water-absorbent resin, 20-30 parts of polyacrylamide microspheres, 20-30 parts of quaternized chitosan, 10-15 parts of modifier and 1-5 parts of catalyst; wherein the modifier is a composition of tartaric acid, 2-acrylamide-2-methylpropanesulfonic acid and N, N '-bis (acryloyl) cystamine in a mass ratio of 1: (2-3): (1-1.5). Wherein the acrylic water-absorbent resin provides basic water-absorbent capacity, the polyacrylamide microspheres enhance adsorption and prevent gel blockage, the quaternized chitosan improves antibacterial property and electrolyte adsorption capacity, the catalyst ensures that the reaction is fully carried out, and all the components of the modifier cooperate with one another to enhance hydrophilicity; the water absorption performance, the structural stability and the salt tolerance of the core layer are jointly improved.

Description

Technical Field

[0001] The present invention relates to the technical field of adult diapers, and particularly relates to a superabsorbent diaper and its preparation method and application. Background Art

[0002] In the current market pattern, as a widely used functional material, superabsorbent resin exhibits relatively prominent water absorption characteristics. The water absorption capacity of the material itself is excellent, and it can absorb up to hundreds of times its own weight of water. This characteristic enables it to play a key role in many fields that require water absorption functions. However, when it comes to the specific scenario of absorbing urine, the performance of superabsorbent resin is not satisfactory. Its urine absorption ability is relatively weak. Generally, the urine absorption ability is only one-tenth or even lower of its water absorption ability.

[0003] To make up for this defect and meet the actual demand for absorption capacity of the product, currently, the industry generally adopts the method of increasing the filling amount of superabsorbent resin. However, this approach brings a series of new problems: In terms of the product form, increasing the filling amount will inevitably make the product become thick and heavy. This not only affects the portability of the product, reduces the comfort of users, but also limits the application scenarios of the product to a certain extent. Moreover, products that are too thick often have obvious defects in terms of absorption speed. Due to the increase in thickness, the diffusion and absorption paths of liquid inside the material become longer, resulting in a slower absorption speed, and the liquid cannot be absorbed in a timely and effective manner, thereby affecting the use effect of the product.

[0004] In view of the above problems, there is an urgent need in the industry to improve the liquid absorption capacity of the composite core layer, especially to focus on enhancing its urine absorption ability, so as to better meet the market demand and improve the comprehensive performance of the product. Summary of the Invention

[0005] The purpose of the present invention is to overcome the deficiencies of the prior art and provide a superabsorbent diaper and its preparation method and application.

[0006] To achieve the above purpose, the technical solution adopted by the present invention is as follows: In the first aspect, the present invention provides a superabsorbent diaper, including a bottom film, a core layer, a surface layer and elastic side seals. The core layer comprises the following raw materials for preparation in parts by weight: 50 - 60 parts of acrylic acid-based superabsorbent resin, 20 - 30 parts of polyacrylamide microspheres, 20 - 30 parts of quaternized chitosan, 10 - 15 parts of a modifier, and 1 - 5 parts of a catalyst; wherein, the modifier is a composition of tartaric acid, 2-acrylamido-2-methylpropanesulfonic acid and N,N'-bis(acryloyl)cystamine with a mass ratio of 1:(2 - 3):(1 - 1.5).

[0007] In the present invention, acrylic acid-based water-absorbing resin is used as the main water-absorbing component. The carboxyl groups (-COOH) on its polymer chain can form hydrogen bonds with water molecules, thereby achieving efficient absorption of urine. The polyacrylamide microspheres have a three-dimensional network structure, and the internal pores can adsorb and store a large amount of urine. Moreover, the amino and amide groups on the surface of the polyacrylamide microspheres can interact with the ions in urine, enhancing the water-absorbing performance. The quaternized chitosan has positively charged quaternary ammonium groups, which generate electrostatic adsorption with the negatively charged ions in urine. While improving the antibacterial performance, it can also promote the adsorption of electrolytes in urine. Moreover, the polyhydroxy structure of quaternized chitosan can form hydrogen bonds with urine molecules, enhancing the water absorbency.

[0008] In order to improve the compatibility of polyacrylamide microspheres and quaternized chitosan in the resin matrix, a modifier is added in the present invention. The sulfonic acid group of 2-acrylamide-2-methylpropanesulfonic acid in the modifier has strong hydrophilicity and ionization ability, and can effectively resist the inhibitory effect of salt ions on the water-absorbing performance in urine. Its sulfonic acid group can form an ion pair with the quaternary ammonium group of chitosan, further improving the salt tolerance of the core layer. The tartaric acid in the modifier forms a hydrogen bond network through carboxyl groups and the hydroxyl groups of the acrylic resin, further improving the network strength of the polymer. Moreover, it can also adjust the surface charge of the polyacrylamide microspheres to prevent their aggregation in the resin matrix. N,N'-bis(acryloyl)cystamine is a compound containing double bonds and cystamine structures, and has good cross-linking performance. It can form cross-linking points in the polymer network, thereby improving the mechanical strength and salt tolerance of the polymer, and helping to maintain the structural stability of the core layer material after absorbing urine.

[0009] The cationic characteristics of quaternized chitosan and the anionic characteristics of acrylic resin form a polyelectrolyte complex, enhancing the network stability through electrostatic attraction. At the same time, the polyacrylamide microspheres are dispersed in the resin matrix as water storage units. Their porous structure can quickly absorb liquid and store it inside the microspheres, while the resin network is responsible for maintaining the overall structural strength.

[0010] Preferably, the catalyst is sodium hypophosphite and potassium persulfate with a mass ratio of 1:(0.5 - 1.5).

[0011] Specifically, the preparation method of the core layer includes the following steps: S1. Stir and disperse quaternized chitosan in an ethanol solution with a volume 2 - 3 times that of quaternized chitosan. After fully mixing evenly, introduce nitrogen into the reaction system, add the catalyst, continue stirring, then add polyacrylamide microspheres, acrylic acid-based water-absorbing resin and the modifier, adjust the pH to 3 - 4, and stir and react at 50 - 60 °C for 1 - 2 h to obtain a slurry; S2. Inject the slurry into a mold for molding treatment to form a preliminary blank of the absorption core layer, and dry it to obtain the core layer.

[0012] Preferably, in the step S1, the volume concentration of the ethanol solution is 70-80%, and the stirring speed is 300-500 r / min.

[0013] Preferably, in the step S2, the temperature for the forming treatment is 80-90 °C, the drying temperature is 100-120 °C, and the drying time is 10-20 min.

[0014] Preferably, the surface layer is non-woven fabric.

[0015] Preferably, the bottom film is a PTFE microporous membrane.

[0016] Preferably, the elastic side seal is non-woven fabric containing 20-30 wt% spandex.

[0017] In a second aspect, the present invention provides a method for preparing the superabsorbent diaper described in the first aspect, comprising the following steps: (1) Apply hot melt adhesive on the back of the surface layer and the front of the bottom film respectively, place the dried core layer between the surface layer and the bottom film, and perform hot pressing and compounding to obtain a semi-finished product; (2) Cut, fold, and press the edges of the semi-finished product, and add elastic side seals to both sides of the diaper to obtain the superabsorbent diaper.

[0018] Preferably, the coating amount of the hot melt adhesive is 2-4 g / m 2 .

[0019] Preferably, the temperature for hot pressing is 130-150 °C, and the pressure for hot pressing is 0.3-0.5 MPa.

[0020] Compared with the prior art, the beneficial effects of the present invention are as follows: The preparation raw materials of the core layer of the superabsorbent diaper cooperate with each other through their respective unique chemical structures and functions to form a synergistic effect, thereby achieving the superabsorbent performance for urine. Specifically, the acrylic acid-based water-absorbing resin provides the basic water-absorbing ability, the polyacrylamide microspheres enhance adsorption and prevent gel blockage, the quaternized chitosan improves antibacterial properties and electrolyte adsorption ability, the catalyst ensures the full progress of the reaction, and the modifier components synergistically enhance the hydrophilicity among each other, jointly improving the water-absorbing performance, structural stability, and salt tolerance of the core layer. Specific Embodiments

[0021] To better illustrate the purpose, technical solution, and advantages of the present invention, the present invention will be further described below in conjunction with specific embodiments.

[0022] The sources of the raw materials used in the following examples and comparative examples are as follows: Polyacrylamide microspheres: The manufacturer is Xi'an Wande Energy Chemical Co., Ltd., and the model is WQ50; Acrylic acid-based water-absorbing resin: The manufacturer is Shandong Linchuan Water Technology Co., Ltd., and the model is lkh001; Quaternized chitosan: The CAS number is 70694-72-3; Tartaric acid: The CAS number is 133-37-9; 2-Acrylamide-2-methylpropanesulfonic acid: The CAS number is 15214-89-8; N,N'-Bis(acryloyl)cystamine: The CAS number is 60984-57-8.

[0023] Other materials, reagents, etc. used in the examples and comparative examples can be obtained from commercial sources without special instructions.

[0024] Example 1

[0025] A super-absorbent diaper, comprising a bottom film, a core layer, a surface layer, and elastic side seals; the surface layer is a non-woven fabric, the bottom film is a PTFE microporous film, and the elastic side seals are non-woven fabrics containing 25 wt% spandex; Among them, the core layer comprises the following raw materials in parts by weight: 52 parts of acrylic acid-based water-absorbing resin, 25 parts of polyacrylamide microspheres, 22 parts of quaternized chitosan, 14 parts of a modifier, and 3 parts of a catalyst; among them, the modifier is tartaric acid, 2-acrylamide-2-methylpropanesulfonic acid, and N,N'-bis(acryloyl)cystamine with a mass ratio of 1:2.5:1.4, and the catalyst is sodium hypophosphite and potassium persulfate with a mass ratio of 1:1; Specifically, the preparation method of the core layer comprises the following steps: S1. Stir and disperse quaternized chitosan in 2.5 times the volume of an ethanol solution with a volume concentration of 75% at a rotation speed of 400 r / min. After fully mixing, introduce nitrogen into the reaction system, add the catalyst, continue to stir at a rotation speed of 400 r / min, then add polyacrylamide microspheres, acrylic acid-based water-absorbing resin, and the modifier, adjust the pH to 3, and stir and react at 55 °C and a rotation speed of 400 r / min for 1.5 h to obtain a slurry; S2. Inject the slurry into a mold for molding to form a preliminary blank of the absorbent core layer, and dry it to obtain the core layer; among them, the temperature of the molding process is 85 °C, the drying temperature is 100 °C, and the drying time is 15 min; The preparation method of the super-absorbent diaper comprises the following steps: (1) Coat hot melt adhesive on the back of the surface layer and the front of the bottom film respectively, place the dried core layer between the surface layer and the bottom film, and perform hot pressing and compounding to obtain a semi-finished product; among them, the temperature of the hot pressing is 140 °C, and the pressure of the hot pressing is 0.4 MPa; the coating amount of the hot melt adhesive is 3 g / m 2 ; (2) Cut, fold, and press the edges of the semi-finished product, and add elastic side seals to both sides of the diaper to obtain the super-absorbent diaper.

[0026] Example 2

[0027] A super-absorbent diaper, comprising a bottom film, a core layer, a surface layer, and elastic side seals; the surface layer is non-woven fabric, the bottom film is a PTFE microporous film, and the elastic side seals are non-woven fabrics containing 20 wt% spandex; Among them, the core layer comprises the following raw materials in parts by weight: 50 parts of acrylic acid-based water-absorbing resin, 20 parts of polyacrylamide microspheres, 20 parts of quaternized chitosan, 10 parts of a modifier, and 1 part of a catalyst; among them, the modifier is tartaric acid, 2-acrylamide-2-methylpropanesulfonic acid, and N,N'-bis(acryloyl)cystamine with a mass ratio of 1:2:1, and the catalyst is sodium hypophosphite and potassium persulfate with a mass ratio of 1:0.5; Specifically, the preparation method of the core layer comprises the following steps: S1. Stir and disperse quaternized chitosan in 2 times the volume of 70% ethanol solution at a speed of 300 r / min. After fully mixing evenly, introduce nitrogen into the reaction system, add the catalyst, continue to stir at a speed of 300 r / min, then add polyacrylamide microspheres, acrylic acid-based water-absorbing resin, and the modifier, adjust the pH to 3, and stir and react at 50 °C and 300 r / min for 2 h. After the reaction, a slurry is obtained; S2. Inject the slurry into a mold for molding to form a preliminary absorbent core layer blank, and dry it to obtain the core layer; among them, the temperature of the molding process is 80 °C, the drying temperature is 100 °C, and the drying time is 20 min; The preparation method of the super-absorbent diaper comprises the following steps: (1) Coat hot melt adhesive on the back of the surface layer and the front of the bottom film respectively, place the dried core layer between the surface layer and the bottom film, and perform hot pressing and lamination to obtain a semi-finished product; among them, the temperature of the hot pressing is 130 °C, and the pressure of the hot pressing is 0.3 MPa; the coating amount of the hot melt adhesive is 2 g / m 2 ; (2) Cut, fold, and press the edges of the semi-finished product, and add elastic side seals to both sides of the diaper to obtain the super-absorbent diaper.

[0028] Example 3

[0029] A super-absorbent diaper, comprising a bottom film, a core layer, a surface layer, and elastic side seals; the surface layer is non-woven fabric, the bottom film is a PTFE microporous film, and the elastic side seals are non-woven fabrics containing 30 wt% spandex; Among them, the core layer comprises the following raw materials for preparation in parts by weight: 60 parts of acrylic acid-based water-absorbing resin, 30 parts of polyacrylamide microspheres, 30 parts of quaternized chitosan, 15 parts of modifier and 5 parts of catalyst; wherein, the modifier is tartaric acid, 2-acrylamido-2-methylpropanesulfonic acid and N,N'-bis(acryloyl)cystamine with a mass ratio of 1:3:1.5, and the catalyst is sodium hypophosphite and potassium persulfate with a mass ratio of 1:1.5; Specifically, the preparation method of the core layer comprises the following steps: S1. Stir and disperse quaternized chitosan in 3 times the volume of an ethanol solution with a volume concentration of 80% at a rotation speed of 500 r / min. After fully mixing evenly, introduce nitrogen into the reaction system, add the catalyst, continue to stir at a rotation speed of 500 r / min, then add polyacrylamide microspheres, acrylic acid-based water-absorbing resin and the modifier, adjust the pH to 4, and stir and react at 60 °C and a rotation speed of 500 r / min for 1 h to obtain a slurry; S2. Inject the slurry into a mold for forming treatment to form a preliminary blank of the absorption core layer, and dry it to obtain the core layer; wherein, the temperature of the forming treatment is 90 °C, and the temperature of drying is 120 °C for 10 min; The preparation method of the superabsorbent diaper comprises the following steps: (1) Coat hot melt adhesive on the back of the surface layer and the front of the bottom film respectively, place the dried core layer between the surface layer and the bottom film, and perform hot pressing and compounding to obtain a semi-finished product; wherein, the temperature of hot pressing is 130-150 °C, and the pressure of hot pressing is 0.3-0.5 MPa; the coating amount of the hot melt adhesive is 4 g / m 2 ; (2) Cut, fold and edge the semi-finished product, and add elastic side seals to both sides of the diaper to obtain the superabsorbent diaper.

[0030] Comparative Example 1 The difference between Comparative Example 1 and Example 1 is that: the addition amount of the modifier remains unchanged, tartaric acid is not added, and 2-acrylamido-2-methylpropanesulfonic acid and N,N'-bis(acryloyl)cystamine with a mass ratio of 2.5:1.4 are used to make up the missing amount.

[0031] Comparative Example 2 The difference between Comparative Example 2 and Example 1 is that: the addition amount of the modifier remains unchanged, 2-acrylamido-2-methylpropanesulfonic acid is not added, and tartaric acid and N,N'-bis(acryloyl)cystamine with a mass ratio of 1:1.4 are used to make up the missing amount.

[0032] Comparative Example 3 The difference between Comparative Example 3 and Example 1 lies in that: the addition amount of the modifier remains unchanged, N,N'-bis(acryloyl)cystamine is not added, and the missing amount is made up with tartaric acid and 2-acrylamido-2-methylpropanesulfonic acid in a mass ratio of 1:2.5.

[0033] Comparative Example 4 The difference between Comparative Example 4 and Example 1 lies in that: the addition amount of the modifier remains unchanged, and the mass ratio of tartaric acid, 2-acrylamido-2-methylpropanesulfonic acid and N,N'-bis(acryloyl)cystamine is 2.5:1:1.4.

[0034] Comparative Example 5 The difference between Comparative Example 5 and Example 1 lies in that: the addition amount of the modifier remains unchanged, and the mass ratio of tartaric acid, 2-acrylamido-2-methylpropanesulfonic acid and N,N'-bis(acryloyl)cystamine is 1:1.4:2.5.

[0035] Performance Test The absorption effect of the diaper is based on the liquid absorption performance of the core layer. Therefore, in order to more intuitively reflect the liquid absorption performance of the diaper, the following performance tests were carried out on the core layers prepared in Examples 1-3 and Comparative Examples 1-5: (1) Test of water absorption ratio and physiological saline absorption: Cut the core layer of each group into samples with a length of 2 cm, a width of 2 cm, and a thickness of 0.5 cm. Immerse the samples of each group in deionized water and physiological saline (containing 0.9% sodium chloride) respectively. When the liquid absorption reaches equilibrium, hang and stand for 30 min to remove the unabsorbed water or physiological saline, and then weigh the mass of the core layer. The water absorption ratio and physiological saline absorption ratio are both calculated according to the formula Q=(m1 - m2) / m2, where m1 is the mass of the core layer after liquid absorption, and m2 is the mass of the core layer before liquid absorption. Take the arithmetic mean of the three measurement results as the measurement result, and the data results are shown in Table 1.

[0036] (2) Test of absorption speed: Take 100 mL of deionized water in a beaker, put a magnetic rotor in the beaker, place it on a magnetic stirrer, adjust the rotation speed to 600 r / min, cut the core layer of each group into samples with a length of 2 cm, a width of 2 cm, and a thickness of 0.5 cm, and then pour them into the vortex respectively. While absorbing the deionized water, the vortex starts to disappear. Measure the time required for the liquid surface to become static, which is the water absorption speed. The data results are shown in Table 1.

[0037] (3) Reverse osmosis volume test: Cut the core layers of each group into samples with a length of 2 cm, a width of 2 cm, and a thickness of 0.5 cm. Immerse the samples of each group in deionized water, place them at 25 °C and 70% (relative humidity) for 1 h. After taking them out, place a piece of filter paper on their surface, record the mass as m1, press with a 250 g weight for 6 h, and weigh the filter paper weight m2 after 6 h. Calculate the reverse osmosis volume as m2 - m1, and the data results are shown in Table 1.

[0038] Table 1 Test results of the core layer performance of each group Group / Performance Water Absorption Ratio (g / g) Normal Saline Absorption Ratio (g / g) Water Absorption Rate (s) Reverse Osmosis Amount (g) Example 1 272 56 5 0.32 Example 2 264 51 7 0.35 Example 3 278 59 5 0.31 Comparative Example 1 175 33 16 1.20 Comparative Example 2 170 31 18 1.25 Comparative Example 3 178 36 15 1.18 Comparative Example 4 234 40 13 0.91 Comparative Example 5 238 43 12 0.87 As can be seen from Table 1, combining Example 1 and Comparative Examples 1-3, it can be known that the modifiers in Example 1 are selected as the compounding of tartaric acid, 2-acrylamide-2-methylpropanesulfonic acid, and N,N'-bis(acryloyl)cystamine. The core layer absorption performance of Example 1 is better than that of Comparative Examples 1-3. This may be because the sulfonic acid group of 2-acrylamide-2-methylpropanesulfonic acid has strong hydrophilicity and ionization ability, and can effectively resist the inhibitory effect of salt ions on the water absorption performance in urine. N,N'-bis(acryloyl)cystamine is a compound containing double bonds and cystamine structures, and has good cross-linking performance. It can form cross-linking points in the polymer network, thereby improving the mechanical strength and salt tolerance of the polymer. The tartaric acid in the modifier forms a hydrogen bond network with the hydroxyl group of the acrylic resin through the carboxyl group, further improving the network strength of the polymer. Moreover, it can also adjust the surface charge of the polyacrylamide microspheres to prevent their aggregation in the resin matrix. Therefore, the combination of tartaric acid, 2-acrylamide-2-methylpropanesulfonic acid, and N,N'-bis(acryloyl)cystamine can synergistically improve the absorption performance and salt tolerance of the core layer.

[0039] Combining the data of Example 1 and Comparative Examples 4-5, it can be known that when the mass ratio of tartaric acid, 2-acrylamide-2-methylpropanesulfonic acid, and N,N'-bis(acryloyl)cystamine is 1:(2-3):(1-1.5), the absorption performance of the core layer reaches a relatively optimal level.

[0040] In summary, the various modifiers in the diaper core layer of the present invention synergistically enhance the hydrophilicity and jointly improve the water absorption performance, structural stability, and salt tolerance of the core layer.

[0041] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit the protection scope of the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that the technical solutions of the present invention can be modified or equivalently replaced without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. A superabsorbent diaper, comprising a bottom film, a core layer, a surface layer and elastic side seals, characterized in that, The core layer comprises the following raw materials for preparation in parts by weight: 50-60 parts of acrylic acid-based water-absorbing resin, 20-30 parts of polyacrylamide microspheres, 20-30 parts of quaternized chitosan, 10-15 parts of modifier, and 1-5 parts of catalyst; wherein, the modifier is a composition of tartaric acid, 2-acrylamide-2-methylpropanesulfonic acid, and N,N'-bis(acryloyl)cystamine with a mass ratio of 1:(2-3):(1-1.5).

2. The superabsorbent diaper according to claim 1, wherein The catalyst is sodium hypophosphite and potassium persulfate with a mass ratio of 1:(0.5-1.5).

3. The superabsorbent disposable diaper according to claim 1, wherein, The preparation method of the core layer is characterized by comprising the following steps: S1. Stir and disperse quaternized chitosan in an ethanol solution with a volume 2-3 times that of quaternized chitosan, fully mix evenly, then introduce nitrogen into the reaction system, add the catalyst, continue stirring, then add polyacrylamide microspheres, acrylic acid-based water-absorbing resin, and the modifier, adjust the pH to 3-4, and stir and react at 50-60 °C for 1-2 h to obtain a slurry; S2. Inject the slurry into a mold for shaping to form a preliminary blank of the absorption core layer, and dry it to obtain the core layer.

4. The superabsorbent diaper according to claim 3, wherein In the step S2, the temperature for shaping is 80-90 °C, the drying temperature is 100-120 °C, and the drying time is 10-20 min.

5. The superabsorbent diaper according to claim 1, characterized in that, The surface layer is non-woven fabric.

6. The superabsorbent diaper according to claim 1, wherein The bottom film is a PTFE microporous membrane.

7. The superabsorbent disposable diaper according to claim 1, wherein The elastic side seal is non-woven fabric containing 20-30% spandex.

8. The preparation method of the superabsorbent diaper according to any one of claims 1-7, characterized in that, Comprising the following steps: (1) Coat hot melt adhesive on the back of the surface layer and the front of the bottom film respectively, place the dried core layer between the surface layer and the bottom film, and perform hot pressing and compounding to obtain a semi-finished product; (2) Cut, fold, and press the edge of the semi-finished product, and add elastic side seals to both side edges of the diaper to obtain the super-absorbent diaper.

9. The preparation method of the superabsorbent diaper according to claim 8, wherein, The temperature for hot pressing is 130-150 °C, and the pressure for hot pressing is 0.3-0.5 MPa.