Preparation method of super absorbent resin material

Abstract

The invention relates to a preparation method of a super absorbent resin material, the resin is formed by polymerization of an acrylic monomer and konjac glucomannan, and the preparation method specifically comprises the following steps: adding konjac powder into water, adding a composite solvent and a dispersant Tween-80 to obtain a composite system 1, the composite solvent is composed of palm oil and any one of corn oil, soybean oil and rapeseed oil, and the dispersant Tween-80 is composed of a dispersant Tween-80 and a dispersant Tween-80. Continuously adding an initiator ammonium persulfate, initiating to obtain a compound system 2, then adding acrylic acid and NMBA, carrying out polymerization reaction, eluting the edible oil with diethyl ether and ethanol after the reaction is finished, drying, and crushing to obtain the super absorbent resin material. The acrylic monomer and the konjac glucomannan are polymerized to form the resin, the water absorption performance and the water retention performance of the material are effectively improved, the water absorption rate reaches 748.13 times, a small amount of ethyl alcohol is added on the basis to prepare the composite solvent, and the water absorption rate reaches 1018.96 times. The prepared resin material can be applied to hygienic products such as paper diapers and sanitary napkins.

Description

Technical Field

[0001] The invention relates to the technical field of high molecular polymer materials, and in particular to a method for preparing a highly water-absorbent resin material. Background Art

[0002] Super absorbent resin (SAP) is a lightly cross-linked hydrophilic polymer. Super absorbent resins are classified into three categories according to the source of raw materials: natural polymer modified super absorbent resins, synthetic polymer super absorbent resins, and super absorbent resin blends. Among natural polymer materials, starch and cellulose are the most widely studied. However, starch-based super absorbent resins have poor water retention and heat resistance, and low gel strength after absorbing water, which limits its development. Synthetic polymer absorbent resins have a simpler preparation process, strong water absorption and retention capacity, and good product stability. They are currently the most diverse and largest-yield super absorbent materials. However, this type of resin is not easily degraded and will cause environmental pollution.

[0003] Konjac glucomannan (KGM) is a natural high molecular weight polysaccharide with a large number of hydrophilic hydroxyl groups. These groups can form hydrogen bonds with water molecules, thus showing strong water absorption capacity. Therefore, it is one of the main raw materials for preparing SAP. There are many methods for preparing SPA, and solution polymerization is a more common one. Solution polymerization is a homogeneous polymerization process. Due to the presence of organic solvents, this method reduces the viscosity of the reaction system, facilitates the uniform mixing of the solution and the effective transfer of heat, and is beneficial to improving the quality and performance of the polymer. However, due to the large amount of solvents in the system, the monomer concentration is relatively low, which in turn slows down the polymerization rate, resulting in low production efficiency. Secondly, after the reaction, in order to reuse and reduce environmental pollution, the solvent needs to be recovered and purified, but this will increase production costs, and some solvents are difficult to recover.

[0004] In contrast, the reverse suspension polymerization method usually uses an oil-phase organic solvent as a dispersion medium. Its advantage is that the viscosity of the system can be controlled by adjusting the solvent, the reaction conditions are milder, and it is easy to obtain a granular product. However, the disadvantage of this method is that it also uses a large amount of organic solvents, which may cause environmental pollution problems and safety hazards. At the same time, it is difficult to wash and remove organic solvents and recover organic solvents in the later stage, which increases production costs. Secondly, during the reaction process, the uniformity of the droplet size is poor and the polymer particles are prone to adhesion, resulting in unsatisfactory performance of the final product. Summary of the invention

[0005] Based on the above problems, the present invention aims to provide a method for preparing a highly water-absorbent resin material based on a reverse suspension polymerization method. In the process of polymerizing acrylic acid monomer and konjac glucomannan, the method uses edible oil as a solvent, which reduces the use of organic solvents, reduces production costs, improves the uniformity of droplets in the preparation process, inhibits the adhesion of polymer particles, and effectively improves the water absorption performance of the material.

[0006] The purpose of the present invention is achieved through the following technical solutions: A method for preparing a super absorbent resin material, characterized in that it comprises the following steps: (1) Weigh konjac flour and add it to water. Stir it at 35-45°C (stirring speed 300 rpm) for more than 30-50 min to allow it to fully swell and form a solution. (2) adding a composite solvent and a dispersant Tween-80 to the solution of step (1), and stirring for 40 to 50 minutes to obtain a composite system 1, wherein the composite solvent is any one of corn oil, soybean oil and rapeseed oil and palm oil; (3) adding ammonium persulfate as an initiator to the composite system 1 of step (2) and initiating for 35 to 45 minutes to obtain a composite system 2; (4) Adding acrylic acid neutralized with sodium hydroxide and a crosslinking agent N,N'-methylenebisacrylamide (NMBA) to the composite system 2 of step (3), continuing stirring (stirring rate 300 rpm) and heating it to 65-75 °C for reaction for 40-60 min to obtain a composite system 3; (5) After the reaction is completed, the edible oil is eluted with ether and ethanol, and then dried and crushed to obtain a highly absorbent resin material.

[0007] Furthermore, in the step (1), the ratio of konjac flour to water is 0.5-2.0 g:100 mL.

[0008] Furthermore, in the step (2), any one of corn oil, soybean oil and rapeseed oil and palm oil are mixed in a volume ratio of 1:1-2 in the composite solvent.

[0009] Preferably, the composite solvent in step (2) is a mixture of rapeseed oil and palm oil in a volume ratio of 1:1.

[0010] More preferably, 5-8% of the total volume of ethanol is also added to the composite solvent.

[0011] Furthermore, in the step (2), the volume ratio of the solution, the composite solvent and Tween 80 in the composite system 1 is 100:80-200:3-5.

[0012] Furthermore, in the step (3) of the composite system 2, the mass ratio of konjac flour to initiator is 0.5-2.0:0.3-0.6.

[0013] Furthermore, the degree of neutralization of acrylic acid neutralized by sodium hydroxide in step (4) is 60-65%, and the amount used is 20-40 times that of konjac flour.

[0014] Furthermore, in the step (4) of the composite system 3, the mass ratio of konjac flour to NMBA is 0.5-2.0:0.10-0.25 g.

[0015] Most specifically, a method for preparing a super absorbent resin material is characterized by comprising the following steps: (1) Weigh konjac flour and add it to water. Stir it at 35-45°C and 250-350 rpm for 30-50 min to fully swell it and form a solution. The ratio of konjac flour to water is 0.5-2.0 g:100 mL. (2) adding a composite solvent and a dispersant Tween-80 to the solution of step (1), stirring at 250-350 rpm for 40-50 min to obtain a composite system 1, wherein the composite solvent is a mixture of any one of corn oil, soybean oil and rapeseed oil and palm oil in a volume ratio of 1:1-2, and then adding 5-8% of the total volume of ethanol to obtain a composite system 1, and the volume ratio of the solution, the composite solvent and Tween 80 is 100:80-200:3-5; (3) adding initiator ammonium persulfate to the composite system 1 of step (2) in a mass ratio of konjac flour to initiator of 0.5-2.0:0.3-0.6, and initiating for 35-45 minutes to obtain composite system 2; (4) Adding acrylic acid neutralized with sodium hydroxide to the composite system 2 of step (3), with a neutralization degree of 60-65%, an acrylic acid monomer amount of 20-40 times that of konjac flour, and a crosslinking agent N,N'-methylenebisacrylamide (NMBA), continuing to stir at 250-350 rpm and heating it to 65-75 °C for 40-60 min to obtain a composite system 3, in which the mass ratio of konjac flour to NMBA is 0.5-2.0:0.10-0.25 g; (5) After the reaction is completed, the edible oil is eluted with ether and ethanol, and then dried and crushed to obtain a highly absorbent resin material.

[0016] When preparing a highly absorbent resin, the present invention uses palm oil as the main component and any one of corn oil, soybean oil and rapeseed oil as the auxiliary component to form a composite oil-soluble system. Palm oil has a high melting point, high viscosity and good thermal stability. By adding components with slightly lower melting points and viscosities such as corn oil, soybean oil or rapeseed oil, the two can be mixed to adjust the viscosity and melting point, thereby adjusting the fluidity of the reaction solvent system. In addition to being used as a solvent, an appropriate amount of unsaturated fatty acids are introduced into the composite solvent, and some unsaturated fatty acids can be copolymerized with acrylic acid. While ensuring a certain water absorption performance, the mechanical strength and salt resistance of the resin can also be improved. Therefore, when the prepared konjac glucomannan material is applied to sanitary products, the water absorption performance and water retention performance are more excellent, and it is not easy to have the situation of back seepage.

[0017] A small amount of polar solvent ethanol is further added to the composite solvent to adjust the viscosity of the solvent, making the mixing uniformity and dispersibility of the oil-soluble system higher, while improving the solubility of the initiator ammonium persulfate in the oil-soluble system. On the one hand, the reaction surface is increased, the initiation efficiency and polymerization efficiency are improved, and on the other hand, a stable buffer interface layer can be formed between the edible oil and the water phase, effectively preventing the collision and merging of the water phase droplets during the reaction process, and improving the stability of the entire system during the polymerization reaction, thereby improving the uniformity and performance consistency of the product and improving the water retention performance of the material. Finally, since the amount of ethanol used is extremely small and it is easy to remove by subsequent washing, the pollution to the environment is extremely small. At the same time, the addition of ethanol is also conducive to the subsequent washing of the edible oil and improves the washing efficiency.

[0018] The present invention has the following technical effects: The present invention uses acrylic acid monomer and konjac glucomannan as raw material polymerization to form resin material process by reverse suspension polymerization, by using composite edible oil as oil phase solvent, solves the problem of environmental pollution and potential safety hazard caused by a large amount of organic solvents used in traditional reverse suspension polymerization, and also effectively improves the water absorption and water retention performance of the material, and the water absorption multiple reaches 748.13 times, and on this basis, adds a small amount of ethanol to prepare composite solvent, further improves the water absorption and water retention performance of the material, and the water absorption multiple reaches 1018.96 times. For physiological saline and simulated blood, it also has excellent absorption performance and water retention performance, which is conducive to the application of the konjac glucomannan material prepared by the present invention in sanitary products such as diapers and sanitary towels, and reverse osmosis is not easy to occur. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 : The flow chart of the present invention for preparing highly water-absorbent konjac glucomannan material.

[0020] Figure 2 : Photos of various stages of the preparation of highly water-absorbent konjac material according to the present invention, a: product of reaction step (4); b: product after washing; c: final product after drying.

[0021] Figure 3 : Water absorption experiment picture of the highly water-absorbent konjac glucomannan material prepared by the present invention. DETAILED DESCRIPTION

[0022] The present invention is described in detail below through examples. It is necessary to point out that the following examples are only used to further illustrate the present invention and cannot be understood as limiting the scope of protection of the present invention. Those skilled in the art can make some non-essential improvements and adjustments to the present invention based on the above-mentioned contents of the present invention.

[0023] Example 1 A method for preparing a super absorbent resin material comprises the following steps: (1) Weigh 0.5 g of konjac flour and add it to 100 mL of water. Stir at 35 °C and 300 rpm for more than 30 min to allow it to fully swell and form a solution. (2) Add 80 mL of a composite solvent and 3.0 mL of Tween-80 to the solution of step (1), and stir at 300 rpm for 40 min to prepare a composite system 1, wherein the composite solvent is a mixture of corn oil and palm oil in a volume ratio of 1:2, and then 5% of the total volume of ethanol is added; (3) adding 0.3 g of initiator ammonium persulfate to the composite system 1 of step (2) and initiating for 40 minutes to obtain a composite system 2; (4) Adding acrylic acid neutralized with sodium hydroxide (neutralization degree 62%, mass ratio of konjac flour to acrylic acid 1:20) and 0.10 g of crosslinking agent N,N'-methylenebisacrylamide (NMBA) to the composite system 2 of step (3), stirring was continued at 300 rpm and the temperature was raised to 60 °C for reaction for 60 min to obtain a composite system 3; (5) After the reaction is completed, the edible oil is eluted with ether and ethanol, and then dried and crushed to obtain a highly absorbent konjac glucomannan material.

[0024] Example 2 A method for preparing a super absorbent resin material comprises the following steps: (1) Weigh 1.0 g of konjac flour and add it to 100 mL of water. Stir at 40 °C and 300 rpm for more than 35 min to allow it to fully swell and form a solution. (2) Adding 100 mL of a composite solvent and 4.0 g of Tween-80 to the solution of step (1), and stirring at 300 rpm for 45 min to prepare a composite system 1, wherein the composite solvent is a mixture of rapeseed oil and palm oil in a volume ratio of 1:1; (3) adding 0.4 g of initiator ammonium persulfate to the composite system 1 of step (2) and initiating for 35 minutes to obtain a composite system 2; (4) Adding acrylic acid neutralized with sodium hydroxide (neutralization degree of 65%, mass ratio of konjac flour to acrylic acid of 1:40) and 0.15 g of crosslinking agent N,N'-methylenebisacrylamide (NMBA) to the composite system 2 of step (3), stirring was continued at 300 rpm and the temperature was raised to 65 °C for reaction for 55 min to obtain a composite system 3; (5) After the reaction is completed, the edible oil is eluted with ether and ethanol, and then dried and crushed to obtain a highly absorbent konjac glucomannan material.

[0025] Example 3 A method for preparing a super absorbent resin material comprises the following steps: (1) Weigh 1.0 g of konjac flour and add it to 100 mL of water. Stir at 40 °C and 300 rpm for more than 35 min to allow it to fully swell and form a solution. (2) Adding 100 mL of a composite solvent and 4.0 g of Tween-80 to the solution of step (1), stirring at 300 rpm for 45 min to prepare a composite system 1, wherein the composite solvent is a mixture of rapeseed oil and palm oil in a volume ratio of 1:1, and then adding 6% of the total volume of ethanol; (3) adding 0.4 g of initiator ammonium persulfate to the composite system 1 of step (2) and initiating for 35 minutes to obtain a composite system 2; (4) Adding acrylic acid neutralized with sodium hydroxide (neutralization degree of 65%, mass ratio of konjac flour to acrylic acid of 1:40) and 0.15 g of crosslinking agent N,N'-methylenebisacrylamide (NMBA) to the composite system 2 of step (3), stirring was continued at 300 rpm and the temperature was raised to 65 °C for reaction for 55 min to obtain a composite system 3; (5) After the reaction is completed, the edible oil is eluted with ether and ethanol, and then dried and crushed to obtain a highly absorbent konjac glucomannan material.

[0026] The actual pictures of the materials prepared in this example at each stage are as follows Figure 2 shown.

[0027] Comparative Example 1 Compared with Example 3, in step (2), only palm oil is used as the solvent, and neither rapeseed oil nor ethanol is added. The remaining steps are the same as those in Example 3, that is, the composite solvent contains only palm oil.

[0028] Comparative Example 2 A method for preparing a super absorbent resin material comprises the following steps: (1) Weigh 1.0 g of konjac flour and add it to 100 mL of water. Stir at 40 °C for more than 35 min to allow it to fully swell and form a solution. (2) Add 100 mL of a composite solvent and 4.0 g of Tween-80 to the solution of step (1), stir for 45 min to obtain a composite system 1, wherein the composite solvent is palm oil, and then add 6% ethanol to the total volume; (3) adding 0.4 g of initiator ammonium persulfate to the composite system 1 of step (2) and initiating for 35 minutes to obtain a composite system 2; (4) Adding acrylic acid neutralized with sodium hydroxide (neutralization degree of 65%, mass ratio of konjac flour to acrylic acid of 1:30) and 0.15 g of crosslinking agent N,N'-methylenebisacrylamide (NMBA) to the composite system 2 of step (3), continuing to stir and heating it to 65 °C for 55 min to obtain a composite system 3; (5) After the reaction is completed, the edible oil is eluted with ether and ethanol, and then dried and crushed to obtain a highly absorbent konjac glucomannan material.

[0029] Compared with Example 3, in step (2) of Comparative Example 2, an equal amount of palm oil was used in the composite solvent to replace rapeseed oil, that is, the composite solvent was palm oil+ethanol.

[0030] Comparative Example 3 Compared with Example 3, cyclohexane is used as the solvent to replace the composite solvent in step (2), and the remaining steps are the same as Example 3.

[0031] Example 4 A method for preparing a super absorbent resin material comprises the following steps: (1) Weigh 1.5 g of konjac flour and add it to 100 mL of water. Stir at 35 °C and 250 rpm for more than 40 min to allow it to fully swell and form a solution. The ratio of konjac flour to water is 1.5 g:100 mL. (2) Adding 150 mL of a composite solvent and 4.0 g of Tween-80 to the solution of step (1), stirring at 250 rpm for 45 min to prepare a composite system 1, wherein the composite solvent is a mixture of soybean oil and palm oil in a volume ratio of 1:1.5, and then adding 7% of the total volume of ethanol; (3) adding 0.6 g of initiator ammonium persulfate to the composite system 1 of step (2) and initiating for 45 minutes to obtain the composite system 2; (4) Adding acrylic acid neutralized with sodium hydroxide (neutralization degree 60%, mass ratio of konjac flour to acrylic acid 1:20) and 0.20 g of crosslinking agent N,N'-methylenebisacrylamide (NMBA) to the composite system 2 of step (3), stirring was continued at 250 rpm and the temperature was raised to 70 °C for reaction for 50 min to obtain a composite system 3; (5) After the reaction is completed, the edible oil is eluted with ether and ethanol, and then dried and crushed to obtain a highly absorbent konjac glucomannan material.

[0032] Example 5 A method for preparing a super absorbent resin material comprises the following steps: (1) Weigh 2.0 g of konjac flour and add it to 100 mL of water. Stir at 40 °C and 350 rpm for more than 50 min to allow it to fully swell and form a solution. (2) Adding 200 mL of a composite solvent and 5.0 mL of Tween-80 to the solution of step (1), stirring at 350 rpm for 50 min to prepare a composite system 1, wherein the composite solvent is a mixture of rapeseed oil and palm oil in a volume ratio of 1:2, and then adding 8% of the total volume of ethanol; (3) 0.6 g of initiator ammonium persulfate was added to the composite system 1 of step (2) and the initiator was activated for 45 minutes to obtain the composite system 2; (4) Adding acrylic acid neutralized with sodium hydroxide (neutralization degree 65%, mass ratio of konjac flour to acrylic acid 1:30) and 0.25 g of crosslinking agent N,N'-methylenebisacrylamide (NMBA) to the composite system 2 of step (3), stirring was continued at 350 rpm and the temperature was raised to 75 °C for reaction for 40 min to obtain a composite system 3; (5) After the reaction is completed, the edible oil is eluted with ether and ethanol, and then dried and crushed to obtain a highly absorbent konjac glucomannan material.

[0033] Performance Testing: The prepared konjac glucomannan material was placed in distilled water, 0.9% saline and simulated blood, and its water absorption rate (weight of liquid absorbed by the sample / initial weight of the sample) was measured after it was fully swollen. Then it was placed in a specific pressure environment (simulating the pressure on the material under conditions such as human movement). After a period of time, the amount of liquid exuded from the material was observed and measured, and the water retention rate (residual water absorption / initial water absorption) was calculated. The simulated national standard artificial sperm blood component composition is: sodium carboxymethyl cellulose 5g, sodium chloride 10g, sodium carbonate 40g, glycerol 140mL, sodium phenylpropionate 1.0g, standard medium 1% 10mL, water 860mL. The results are shown in Table 1.

[0034] Table 1:

[0035] It can be seen from the above table that when palm oil is used as a solvent alone (Comparative Example 1), the water absorption performance of the prepared konjac glucomannan material is not ideal. On this basis, rapeseed oil and palm oil are used to form a composite solvent (Example 2), and the water absorption performance of the prepared material is significantly improved. On the basis of Example 2, a small amount of ethanol is further added to prepare a composite solvent (Example 3), and the water absorption performance and water retention performance of the prepared material are further significantly improved. Compared with Example 2, the water absorption rates of distilled water, saline and simulated blood are increased by 34.40%, 33.52% and 30.23%, respectively. In Comparative Example 2, a single palm oil and ethanol are used to prepare a composite solvent, and the water absorption rate of the prepared material is low, and although the water absorption performance is improved compared to Comparative Example 1 using palm oil as a solvent alone, the improvement effect is not obvious. Compared with Comparative Example 1, the water absorption rates of distilled water, saline and simulated blood are only increased by 6.37%, 5.71% and 4.79%, respectively. That is, the regulating and synergistic effect of ethanol is more significant in the system of the two edible oils composite described in the present invention. During the experiment, the performance of the product prepared directly using polar solvents such as ethanol as the oil phase solvent was extremely poor. The water absorption performance of the product prepared using cyclohexane as the solvent in Comparative Example 3 was significantly improved compared with Comparative Examples 1 and 2, but the difference was still large compared with Example 3, and the use of a large amount of organic solvents increased the subsequent washing, recovery and other costs.

Claims

1. A method for preparing a super absorbent resin material, characterized in that: The steps include: (1) Weigh konjac flour and add it to water. Stir it at 35-45°C for more than 30-50 minutes to allow it to fully swell and form a solution. (2) adding a composite solvent and a dispersant Tween-80 to the solution of step (1), and stirring for 40 to 50 minutes to obtain a composite system 1, wherein the composite solvent is composed of any one of corn oil, soybean oil and rapeseed oil and palm oil; (3) adding initiator ammonium persulfate to the composite system 1 of step (2) and initiating for 35 to 45 minutes to obtain composite system 2; (4) Adding acrylic acid neutralized with sodium hydroxide and a crosslinking agent N,N'-methylenebisacrylamide (NMBA) to the composite system 2 of step (3), continuing to stir and heating it to 65-75°C, and polymerizing for 40-60 minutes to obtain a composite system 3; (5) After the reaction is completed, the edible oil is eluted with ether and ethanol, and then dried and crushed to obtain a resin material of highly absorbent konjac glucomannan and acrylic acid polymerization.

2. The method for preparing a super absorbent resin material according to claim 1, wherein: In the step (1), the dosage ratio of konjac flour to water is 0.5-2.0 g:100 mL.

3. A method for preparing a super absorbent resin material as claimed in claim 1 or 2, characterized in that: In the step (2), any one of corn oil, soybean oil and rapeseed oil and palm oil are mixed in the composite solvent at a volume ratio of 1:1-2.

4. A method for preparing a super absorbent resin material according to any one of claims 1 to 3, characterized in that: In the step (2), the volume ratio of the composite solvent to Tween 80 in the composite system 1 is 100:80-200:3-5.

5. A method for preparing a super absorbent resin material according to any one of claims 1 to 4, characterized in that: In the step (3), the mass ratio of konjac flour to initiator in the composite system 2 is 0.5-2.0:0.3-0.

6.

6. The method for preparing a super absorbent resin material according to claim 5, characterized in that: In the step (4), the degree of neutralization of the acrylic acid neutralized by sodium hydroxide is 60-65%, and the mass ratio of konjac flour to acrylic acid is 1:20-40.

7. The method for preparing a super absorbent resin material according to claim 6, characterized in that: The mass ratio of konjac flour to NMBA in the composite system 3 of step (4) is 0.5-2.0:0.10-0.25 g.

8. A method for preparing a super absorbent resin material, characterized in that: The steps include: (1) Weigh konjac flour and add it to water. Stir it at 35-45°C and 250-350 rpm for 30-50 min to fully swell it and form a solution. The ratio of konjac flour to water is 0.5-2.0 g:100 mL. (2) adding a composite solvent and a dispersant Tween-80 to the solution of step (1), stirring at 250-350 rpm for 40-50 min to prepare a composite system 1, wherein the composite solvent is a mixture of any one of corn oil, soybean oil and rapeseed oil and palm oil in a volume ratio of 1:1-2, and then adding 5-8% of the total volume of ethanol, and the volume ratio of the composite solvent to Tween 80 is 100:80-200:3-5; (3) adding initiator ammonium persulfate to the composite system 1 of step (2) in a mass ratio of konjac flour to initiator of 0.5-2.0:0.3-0.6, and initiating for 35-45 minutes to obtain composite system 2; (4) Adding acrylic acid neutralized with sodium hydroxide to the composite system 2 of step (3), with a neutralization degree of 60-65%, a monomer addition amount of 20-40 times that of konjac flour, and a crosslinking agent N,N'-methylenebisacrylamide (NMBA), stirring at 250-350 rpm and heating to 65-75 °C for 40-60 min to obtain a composite system 3, in which the mass ratio of konjac flour to NMBA is 0.5-2.0:0.10-0.25 g; (5) After the reaction is completed, the edible oil is eluted with ether and ethanol, and then dried and crushed to obtain a highly absorbent resin material.

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