Interpenetrating network resin with high water retention rate and preparation method thereof

Abstract

The invention provides a high-water-retention-rate water-absorbent resin and a preparation method thereof. Aiming at the problems of poor water retention performance and the like of the traditional water-absorbent resin, in a polyacrylic acid-acrylamide and polyvinyl alcohol double-network system, a hyperbranched polysiloxane prepolymer and a traditional cross-linking agent are compounded for use to jointly prepare the high-water-retention-rate interpenetrating network water-absorbent resin, and the high-water-retention-rate interpenetrating network water-absorbent resin can be practically applied to the fields of agricultural water-retaining agents, industrial slow-release materials and the like.

Description

Technical Field

[0001] This invention belongs to the field of polymer material preparation, specifically relating to a high water retention water-absorbing resin and its preparation method. Background Technology

[0002] Water-absorbing resins are widely used in hygiene products, agricultural water-retaining agents, and industrial slow-release materials due to their excellent water absorption and retention properties.

[0003] Currently, the acrylic acid / acrylamide graft copolymer system is mainly used in industry to prepare superabsorbent polymers. These resins typically have extremely high water absorption rates, but their physical cross-linking network is relatively fragile, making them prone to swelling and cracking under pressure or after prolonged immersion, thus significantly reducing their water retention rate. Furthermore, to compensate for this deficiency, existing technologies often improve mechanical strength by adding inorganic fillers (such as clay or zeolite) or simple linear polymers, but this often comes at the cost of sacrificing water absorption rate or increasing production costs.

[0004] Polyvinyl alcohol / polyacrylic acid dual-network interpenetrating superabsorbent polymer (PVA) is a unique composite gel material formed by ingenious physical or chemical methods, which interpenetrate and entangle the strong but weakly hydrophilic PVA network with the highly absorbent but mechanically weak PAA network at the molecular level. This structure is not a simple physical blend, but rather forms two independent but interlocked three-dimensional networks, namely "interpenetrating polymer networks".

[0005] Hyperbranched polysiloxanes are unique organic-inorganic hybrid polymers with a structure intermediate between ordinary linear polymers and symmetrical dendritic macromolecules, possessing numerous terminal functional groups and a three-dimensional structure. Hyperbranched polysiloxanes can be used as multifunctional crosslinking agents or nanofillers. Their three-dimensional spherical structure and abundant surface functional groups serve as multifunctional crosslinking points, chemically bonding with acrylamide and acrylic acid. Hyperbranched polysiloxanes themselves possess the properties of organosilicon materials and can act as reinforcing nanofillers.

[0006] Currently, there is limited research on the application of hyperbranched polysiloxane prepolymers in superabsorbent polymers, especially their use as a composite crosslinking agent to improve the water retention performance of superabsorbent polymers. Summary of the Invention

[0007] The purpose of this invention is to provide a high water-retention rate water-absorbing resin and its preparation method. Addressing the problem of poor water retention in traditional water-absorbing resins, this invention utilizes a hyperbranched polysiloxane prepolymer and a traditional crosslinking agent in a polyacrylic acid-acrylamide and polyvinyl alcohol dual-network system to jointly prepare a high water-retention rate interpenetrating network water-absorbing resin. This resin can be practically applied in fields such as agricultural water-retaining agents and industrial slow-release materials.

[0008] To achieve the above objectives, the present invention adopts the following technical solution:

[0009] A method for preparing a high water retention interpenetrating network superabsorbent polymer (SAP) includes the following steps:

[0010] (1) Preparation of hyperbranched polysiloxane prepolymer: Take γ-methacryloxypropyltrimethoxysilane, add dilute hydrochloric acid, heat and stir to react, and rotary evaporate to obtain hyperbranched polysiloxane prepolymer;

[0011] (2) Preparation of interpenetrating network water-absorbing resin: A neutralizing agent is added to acrylic acid to obtain an acrylic acid solution, and then acrylamide, the hyperbranched polysiloxane prepolymer prepared in step (1), N,N-methylenebisacrylamide, and polyvinyl alcohol solution are added to it. After stirring and dispersing, an initiator is added to carry out a polymerization reaction. After the reaction is completed, the polymer is dried to obtain an interpenetrating network water-absorbing resin with high water retention rate.

[0012] Furthermore, in step (1), the molar ratio of water to siloxane in dilute hydrochloric acid is controlled to be 1.2-1.3:1.

[0013] Furthermore, in step (1), the reaction temperature is 30-60℃ and the reaction time is 4-6h.

[0014] Furthermore, in step (2), the mass ratio of acrylic acid, acrylamide, hyperbranched polysiloxane prepolymer, N,N-methylenebisacrylamide, polyvinyl alcohol, and initiator is 50-100:10-50:0.01-0.1:0.01-0.1:10-50:0.1-0.5.

[0015] Furthermore, in step (2), the mass ratio of hyperbranched polysiloxane prepolymer to N,N-methylenebisacrylamide is 1:3-3:1.

[0016] Furthermore, in step (2), the mass ratio of hyperbranched polysiloxane prepolymer to N,N-methylenebisacrylamide is 1:1.

[0017] Furthermore, the neutralizing agent in step (2) is a NaOH solution, and the degree of neutralization of the acrylic acid solution is 70%.

[0018] Furthermore, in step (2), the initiator is ammonium persulfate, the reaction temperature is 60-80℃, and the reaction time is 4-6h.

[0019] Furthermore, in step (2), the polymer is dried in an oven at 60-80℃ for 8-10 hours.

[0020] A high water retention interpenetrating network water-absorbing resin is prepared by the above preparation method.

[0021] The significant advantages of this invention are:

[0022] (1) The water-absorbing resin prepared by the present invention contains two interpenetrating polymer networks, which greatly improves the mechanical strength, toughness and structural stability of the resin. The interpenetrating structure can achieve high water absorption in one network and provide support in the other network, thereby achieving both high water retention and excellent compressive and tensile strength.

[0023] (2) The chemically cross-linked poly(acrylic acid-acrylamide) network, the physically cross-linked PVA network, and the hyperbranched polysiloxane as a nano-reinforcing cross-linking agent jointly construct a strong and fatigue-resistant IPN structure, which enables the resin to maintain a good shape in the swollen state and has significantly better resistance to compression, shear and water retention than traditional resins.

[0024] (3) The present invention uses thermally initiated free radical polymerization, which does not require special equipment. The preparation method is simple and the conditions are mild. The main raw materials are all commercially available common chemicals, which are easy to achieve large-scale production and have high industrialization potential. Detailed Implementation

[0025] To provide a clearer understanding of the technical approach and beneficial effects of the present invention, the technical solution described below is further explained in conjunction with specific embodiments. The water absorption rate test method is as follows: a certain mass of water-absorbing resin is added to water to swell, and after fully absorbing water, the surface moisture is wiped off and the resin is weighed. Water absorption rate = mass of saturated water-absorbing resin / mass of dried resin. The water retention rate test method is as follows: saturated water-absorbing resin is placed in a 60°C constant temperature oven and dried for 6 hours. The weight of the water-absorbing resin before and after drying is measured to calculate the water retention rate. Water retention rate = mass of residual water-absorbing resin / mass of initial water-absorbing resin.

[0026] Example 1

[0027] A method for preparing a high water retention interpenetrating network superabsorbent polymer (SAP) includes the following steps:

[0028] (1) Preparation of hyperbranched polysiloxane prepolymer: γ-methyl lactoneoxynetrimethoxysilane was added to dilute hydrochloric acid and heated to 50°C for 5 hours. The hyperbranched polysiloxane prepolymer was obtained by rotary evaporation. The molar ratio of water to siloxane in dilute hydrochloric acid was controlled to be 1.3:1.

[0029] (2) Preparation of interpenetrating network water-absorbing resin: NaOH solution was added dropwise to 60g of acrylic acid to obtain an acrylic acid solution with a neutralization degree of 70%. Then, 10g of acrylamide, 0.02g of hyperbranched polysiloxane prepolymer prepared in step (1), 0.02g of N,N-methylenebisacrylamide, and 12g of polyvinyl alcohol solution were added to the solution. After stirring and dispersing, 0.4g of ammonium persulfate was added and reacted at 70℃ for 6h. After the reaction was completed, the polymer was placed in a 60℃ oven and dried for 8h to obtain an interpenetrating network water-absorbing resin with high water retention rate.

[0030] After testing, the water-absorbing resin prepared in Example 1 had a water retention rate of 92% and a water absorption rate of 1052 g / g.

[0031] Example 2

[0032] A method for preparing a high water retention interpenetrating network superabsorbent polymer (SAP) includes the following steps:

[0033] (1) Preparation of hyperbranched polysiloxane prepolymer: Y-methacryloxypropyltrimethoxysilane was added to dilute hydrochloric acid and heated to 50°C for 5 hours. The hyperbranched polysiloxane prepolymer was obtained by rotary evaporation. The molar ratio of water to siloxane in dilute hydrochloric acid was controlled to be 1.3:1.

[0034] (2) Preparation of interpenetrating network water-absorbing resin: NaOH solution was added dropwise to 60g of acrylic acid to obtain an acrylic acid solution with a neutralization degree of 70%. Then, 10g of acrylamide, 0.03g of the hyperbranched polysiloxane prepolymer prepared in step (1), 0.01g of N,N-methylenebisacrylamide, and 12g of polyvinyl alcohol solution were added to the solution. After stirring and dispersing, 0.4g of ammonium persulfate was added and reacted at 70℃ for 6h. After the reaction was completed, the polymer was placed in a 60℃ oven and dried for 8h to obtain an interpenetrating network water-absorbing resin with high water retention rate.

[0035] After testing, the water-absorbing resin prepared in Example 2 had a water retention rate of 93% and a water absorption rate of 974 g / g.

[0036] Example 3

[0037] A method for preparing a high water retention interpenetrating network superabsorbent polymer (SAP) includes the following steps:

[0038] (1) Preparation of hyperbranched polysiloxane prepolymer: γ-methacryloxypropyltrimethoxysilane was added to dilute hydrochloric acid and heated to 50°C for 5 hours. The hyperbranched polysiloxane prepolymer was obtained by rotary evaporation. The molar ratio of water to siloxane in dilute hydrochloric acid was controlled to be 1.3:1.

[0039] (2) Preparation of interpenetrating network water-absorbing resin: NaOH solution was added dropwise to 60g of acrylic acid to obtain an acrylic acid solution with a neutralization degree of 70%. Then, 10g of acrylamide, 0.01g of the hyperbranched polysiloxane prepolymer prepared in step (1), 0.03g of N,N-methylenebisacrylamide, and 12g of polyvinyl alcohol solution were added to the solution. After stirring and dispersing, 0.4g of ammonium persulfate was added and reacted at 70℃ for 6h. After the reaction was completed, the polymer was placed in a 60℃ oven and dried for 8h to obtain an interpenetrating network water-absorbing resin with high water retention rate.

[0040] After testing, the water-absorbing resin prepared in Example 3 had a water retention rate of 89% and a water absorption rate of 1106 g / g.

[0041] Example 4

[0042] A method for preparing a high water retention interpenetrating network superabsorbent polymer (SAP) includes the following steps:

[0043] (1) Preparation of hyperbranched polysiloxane prepolymer: Y-methacryloxypropyltrimethoxysilane was added to dilute hydrochloric acid and heated to 50°C for 6 hours. The hyperbranched polysiloxane prepolymer was obtained by rotary evaporation. The molar ratio of water to siloxane in dilute hydrochloric acid was controlled to be 1.2:1.

[0044] (2) Preparation of interpenetrating network water-absorbing resin: NaOH solution was added dropwise to 65g of acrylic acid to obtain an acrylic acid solution with a neutralization degree of 70%. Then, 12g of acrylamide, 0.02g of hyperbranched polysiloxane prepolymer prepared in step (1), 0.02g of N,N-methylenebisacrylamide, and 14g of polyvinyl alcohol solution were added to the solution. After stirring and dispersing, 0.3g of ammonium persulfate was added and reacted at 75℃ for 5h. After the reaction was completed, the polymer was placed in a 70℃ oven and dried for 8h to obtain an interpenetrating network water-absorbing resin with high water retention rate.

[0045] After testing, the water-absorbing resin prepared in Example 4 had a water retention rate of 90% and a water absorption rate of 1012 g / g.

[0046] Example 5

[0047] A method for preparing a high water retention interpenetrating network superabsorbent polymer (SAP) includes the following steps:

[0048] (1) Preparation of hyperbranched polysiloxane prepolymer: Y-methacryloxypropyltrimethoxysilane was added to dilute hydrochloric acid and heated to 50°C for 4 hours. The hyperbranched polysiloxane prepolymer was obtained by rotary evaporation. The molar ratio of water to siloxane in dilute hydrochloric acid was controlled to be 1.2:1.

[0049] (2) Preparation of interpenetrating network water-absorbing resin: NaOH solution was added dropwise to 50g of acrylic acid to obtain an acrylic acid solution with a neutralization degree of 70%. Then, 15g of acrylamide, 0.02g of the hyperbranched polysiloxane prepolymer prepared in step (1), 0.02g of N,N-methylenebisacrylamide, and 15g of polyvinyl alcohol solution were added to the solution. After stirring and dispersing, 0.5g of ammonium persulfate was added and reacted at 70℃ for 7h. After the reaction was completed, the polymer was placed in a 60℃ oven and dried for 10h to obtain an interpenetrating network water-absorbing resin with high water retention rate.

[0050] After testing, the water-absorbing resin prepared in Example 5 had a water retention rate of 91% and a water absorption rate of 1096 g / g.

[0051] Example 6

[0052] A method for preparing a high water retention interpenetrating network superabsorbent polymer (SAP) includes the following steps:

[0053] (1) Preparation of hyperbranched polysiloxane prepolymer: Y-methacryloxypropyltrimethoxysilane was added to dilute hydrochloric acid and heated to 60℃ for 6h. The hyperbranched polysiloxane prepolymer was obtained by rotary evaporation. The molar ratio of water to siloxane in dilute hydrochloric acid was controlled to be 1.3:1.

[0054] (2) Preparation of interpenetrating network water-absorbing resin: NaOH solution was added dropwise to 65g of acrylic acid to obtain an acrylic acid solution with a neutralization degree of 70%. Then, 8g of acrylamide, 0.02g of the hyperbranched polysiloxane prepolymer prepared in step (1), 0.02g of N,N-methylenebisacrylamide, and 15g of polyvinyl alcohol solution were added to the solution. After stirring and dispersing, 0.5g of ammonium persulfate was added and reacted at 80℃ for 4h. After the reaction was completed, the polymer was placed in a 70℃ oven and dried for 8h to obtain an interpenetrating network water-absorbing resin with high water retention rate.

[0055] After testing, the water-absorbing resin prepared in Example 6 had a water retention rate of 89% and a water absorption rate of 1115 g / g.

[0056] Comparative Example 1

[0057] The difference between this comparative example and Example 1 is that hyperbranched polysiloxane prepolymer is not added, and the amount of N,N-methylenebisacrylamide is adjusted. The specific steps are as follows:

[0058] A method for preparing a high water retention interpenetrating network superabsorbent polymer (SAP) includes the following steps:

[0059] Preparation of interpenetrating polymer network (IPN) water-absorbing resin: NaOH solution was added dropwise to 60g of acrylic acid to obtain an acrylic acid solution with a neutralization degree of 70%. Then, 10g of acrylamide, 0.04g of N,N-methylenebisacrylamide, and 12g of polyvinyl alcohol solution were added to the solution. After stirring and dispersing, 0.4g of ammonium persulfate was added and the reaction was carried out at 70℃ for 6h. After the reaction was completed, the polymer was placed in a 60℃ oven and dried for 8h to obtain an interpenetrating polymer network water-absorbing resin with high water retention rate.

[0060] After testing, the water-absorbing resin prepared in Comparative Example 1 had a water retention rate of 78% and a water absorption rate of 1290 g / g.

[0061] Comparative Example 2

[0062] The difference between this comparative example and Example 1 is that N,N-methylenebisacrylamide is not added, and the amount of hyperbranched polysiloxane prepolymer is adjusted. The specific steps are as follows:

[0063] A method for preparing a high water retention interpenetrating network superabsorbent polymer (SAP) includes the following steps:

[0064] (1) Preparation of hyperbranched polysiloxane prepolymer: Y-methacryloxypropyltrimethoxysilane was added to dilute hydrochloric acid and heated to 50°C for 5 hours. The hyperbranched polysiloxane prepolymer was obtained by rotary evaporation. The molar ratio of water to siloxane in dilute hydrochloric acid was controlled to be 1.3:1.

[0065] (2) Preparation of interpenetrating network water-absorbing resin: NaOH solution was added dropwise to 60g of acrylic acid to obtain an acrylic acid solution with a neutralization degree of 70%. Then, 10g of acrylamide, 0.04g of the hyperbranched polysiloxane prepolymer prepared in step (1) and 12g of polyvinyl alcohol solution were added to it. After stirring and dispersing, 0.4g of ammonium persulfate was added and reacted at 70℃ for 6h. After the reaction was completed, the polymer was placed in a 60℃ oven and dried for 8h to obtain an interpenetrating network water-absorbing resin with high water retention rate.

[0066] After testing, the water-absorbing resin prepared in Comparative Example 2 had a water retention rate of 94% and a water absorption rate of 670 g / g.

[0067] A comparison of Example 1 and Comparative Examples 1-2 shows that adding hyperbranched polysiloxane and N,N-methylenebisacrylamide as a combination results in a superabsorbent resin with excellent water retention and absorption rates. Comparative Example 1 only added the traditional crosslinking agent N,N-methylenebisacrylamide, resulting in poor water retention. Comparative Example 2 only added hyperbranched polysiloxane, which slightly improved the water retention but significantly reduced the water absorption rate of the superabsorbent resin. A comparison of Examples 1-3 shows that a mass ratio of hyperbranched polysiloxane to N,N-methylenebisacrylamide between 1:3 and 3:1 can adequately balance the water absorption and water retention rates of the superabsorbent resin, and this range should be prioritized in practical applications.

[0068] The above description is only a preferred embodiment of the present invention. All equivalent changes and modifications made within the scope of the claims of the present invention should be included in the scope of the present invention.

Claims

1. A method for preparing a high water retention interpenetrating network superabsorbent polymer (SAP) resin, comprising the following steps: (1) Preparation of hyperbranched polysiloxane prepolymer: Take γ-methacryloxypropyltrimethoxysilane, add dilute hydrochloric acid, heat and stir to react, and rotary evaporate to obtain hyperbranched polysiloxane prepolymer; (2) Preparation of composite water-absorbing resin: A neutralizing agent is added to acrylic acid to obtain an acrylic acid solution, and then acrylamide, hyperbranched polysiloxane prepolymer prepared in step (1), N,N-methylenebisacrylamide, and polyvinyl alcohol solution are added to it. After stirring and dispersing, an initiator is added to carry out a polymerization reaction. After the reaction is completed, the polymer is dried to obtain a high water retention interpenetrating network water-absorbing resin.

2. The method for preparing the high water retention interpenetrating network water-absorbing resin according to claim 1, characterized in that: In step (1), the molar ratio of water to siloxane in dilute hydrochloric acid is controlled to be 1.2-1.3:

1.

3. The method for preparing the high water retention interpenetrating network water-absorbing resin according to claim 1, characterized in that: In step (1), the reaction temperature is 30-60℃ and the reaction time is 4-6h.

4. The method for preparing the high water retention interpenetrating network water-absorbing resin according to claim 1, characterized in that: In step (2), the mass ratio of acrylic acid, acrylamide, hyperbranched polysiloxane prepolymer, N,N-methylenebisacrylamide, polyvinyl alcohol, and initiator is 50-100:10-50:0.01-0.1:0.01-0.1:10-50:0.1-0.

5.

5. The method for preparing the high water retention interpenetrating network water-absorbing resin according to claim 1, characterized in that: In step (2), the mass ratio of hyperbranched polysiloxane prepolymer to N,N-methylenebisacrylamide is 1:3-3:

1.

6. The method for preparing the high water retention interpenetrating network water-absorbing resin according to claim 1, characterized in that: In step (2), the mass ratio of hyperbranched polysiloxane prepolymer to N,N-methylenebisacrylamide is 1:

1.

7. The method for preparing the high water retention interpenetrating network water-absorbing resin according to claim 1, characterized in that: The neutralizing agent in step (2) is NaOH solution, and the degree of neutralization of the acrylic acid solution is 70%.

8. The method for preparing the high water retention interpenetrating network water-absorbing resin according to claim 1, characterized in that: In step (2), the initiator is ammonium persulfate, the reaction temperature is 60-80℃, and the reaction time is 4-6h.

9. The method for preparing the high water retention interpenetrating network water-absorbing resin according to claim 1, characterized in that: In step (2), the polymer is dried in an oven at 60-80℃ for 8-10 hours.

10. A high water retention interpenetrating network water-absorbing resin prepared by the preparation method according to any one of claims 1-9.