CN102504117B - Aquagel with high water absorbing capacity and preparation method thereof - Google Patents

Abstract

The invention discloses aquagel with high water absorbing capacity. The aquagel is prepared from the following raw materials in percentage by weight: 4-12 percent of polyvinyl alcohol, 70-90 percent of water, 5-20 percent of water-soluble monomers, 0.04-0.4 percent of an initiator and 0.03-0.3 percent of a crosslinking agent. The aquagel with high water absorbing capacity has the appearance characteristics of colorlessness and transparency, has high water absorbing capacity, and is easy for film forming. The invention further discloses a preparation method of the aquagel with high water absorbing capacity. The method comprises the following steps of: dissolving polyvinyl alcohol into a part of water under the conditions of mechanical stirring and nitrogen protection; adding a first water-soluble monomer and a part of the initiator; reacting at the temperature of 70-80 DEG C for 1-2 hours; adding the remaining water, a second water-soluble monomer, the remaining initiator and the crosslinking agent; polymerizing for 2-4 hours, and raising the temperature to 85-95 DEG C; and preserving heat for 0.5-1.5 hours, and cooling to the room temperature to obtain aquagel with high water absorbing capacity. The aquagel has the advantages of high operability, high controllability, easiness for industrial implementation, and the like.

Description

A kind of hydrogel with high water absorption rate and preparation method thereof

technical field

The invention relates to the field of synthesis and modification of polymers, in particular to a hydrogel with high water absorption rate and a preparation method thereof.

Background technique

Hydrogel is a hydrophilic cross-linked polymer with a three-dimensional network structure that can swell in water, absorb and retain a large amount of water without dissolving in water. Hydrogels have a relatively fixed shape, and although the water molecules inside are bound in the gel network, they still have certain mobility. The special structure of the hydrogel system is similar to the structure of organisms, so it has the behavior similar to biological systems. Hydrogel has good biocompatibility, and has only weak interaction with immobilized enzymes or cells, which can keep biomolecules immobilized in hydrogel active for a long time. Due to the unique physical and chemical properties of hydrogels, they are widely used in food processing and preservation, water retaining agents for agriculture and forestry, sanitary products for women and children, industrial separation and concentration materials, water removers, and anti-corrosion materials for construction. Functional materials for various purposes such as leakage sealing materials and medical dressings.

There are many kinds of hydrogels, which can be divided into natural polymer hydrogels and synthetic polymer hydrogels according to the source of polymers. Natural polymer hydrogels mainly include starch series (starch grafting, carboxymethylated starch, etc.), cellulose series (cellulose grafting, carboxymethylated cellulose, etc.), protein series (soybean protein, silk protein, etc.) class, etc.), other natural products and their derivatives series (pectin, alginate, chitosan, etc.). Synthetic polymer hydrogels mainly include polyacrylic acid and its derivatives, polyacrylamide and its derivatives, polyvinyl alcohol, polyvinylpyrrolidone, polyepoxide, etc. Synthetic polymer hydrogels such as polyacrylic acid and its derivatives have attracted much attention because of their high molecular weight, low price and strong water absorption, and are the most widely used.

The preparation methods of hydrogel mainly include aqueous solution polymerization, reverse suspension polymerization, radiation polymerization and so on. Reversed-phase suspension polymerization requires the use of organic solvents, which is likely to cause environmental pollution. Solvent recovery devices need to be added in production, and a small amount of solvent may remain in the product. In addition, when the polymerization reaction temperature is not sensitively controlled, explosion accidents are prone to occur; Polymers have high purity, and the polymerization reaction can be carried out at low temperature and solid phase, and it is easier to control, but the radiation effect is non-selective, which will make the reaction more complicated. Health has a great harmful effect. Considering cost, safety, and environmental protection, aqueous solution polymerization is more suitable for hydrogel preparation.

Low mechanical strength and difficult processing are two significant disadvantages of current hydrogels. Therefore, it is necessary to modify the design of materials for hydrogels, and at the same time improve the water absorption of hydrogels. Polymer blending is an important means of material modification, and has become an effective way to modify polymer materials, which has attracted increasing interest and attention in recent years. Polymer blending can be divided into physical method and chemical method according to the preparation method. The physical method is divided into mechanical blending method, solution blending method and emulsion blending method according to the shape of the materials involved in the blending. The chemical methods include grafting, block copolymerization-blending method to prepare polymer blends and interpenetrating polymer network (IPN) method to form interpenetrating network polymer blends. The application of physical method is the earliest, the process operation is convenient and relatively economical, and it still plays an important role today. Polymer blends prepared by chemical methods have superior properties and have developed rapidly in recent years. The two major disadvantages of hydrogels determine that they are not easy to be modified by physical methods.

However, in the prior art, the hydrogel prepared by the chemical modification method usually has the technical defects of low water absorption rate and difficult processing, and it is necessary to further improve the performance of the hydrogel. Therefore, how to design and synthesize hydrogels with high water absorption and easy processing by chemical modification is of great significance.

Contents of the invention

The invention provides a hydrogel with a high water absorption rate. The hydrogel with a high water absorption rate has a colorless and transparent appearance feature, a high water absorption rate and is easy to process into a film.

A hydrogel with high water absorption rate is made of the following raw materials in weight percentage:

Polyvinyl alcohol 4% to 12%;

Water 70%～90%;

Water-soluble monomer 5% to 20%;

Initiator 0.04%～0.4%;

Cross-linking agent 0.03%～0.3%;

The water-soluble monomer is composed of a first water-soluble monomer and a second water-soluble monomer, and the first water-soluble monomer and the second water-soluble monomer are the same or different.

In order to obtain better invention effect, the present invention is optimized:

Described high water absorption rate hydrogel is made of the raw material of following percentage by weight:

Polyvinyl alcohol 4.15%～5.3%;

Water 78%～84%;

Water-soluble monomer 11%～17%;

Initiator 0.09%～0.15%;

Cross-linking agent 0.08% to 0.17%.

The present invention has no strict requirements on the degree of polymerization of polyvinyl alcohol, and commercially available products can be used, such as polyvinyl alcohol with a degree of polymerization of 500-3000.

In the present invention, there is a strict requirement on the weight percentage of the water-soluble monomer. When the water-soluble monomer is 11% to 17% by weight, the prepared high water absorption hydrogel has a particularly high water absorption.

The first water-soluble monomer is acrylic acid, methacrylic acid, acrylamide, acrylate-2-hydroxyethyl, acrylate-2-hydroxypropyl, methacrylate-2-hydroxyethyl, methacrylate-2 - one or more of hydroxypropyl esters; the second water-soluble monomer is acrylic acid, methacrylic acid, acrylamide, 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, methyl One or more of 2-hydroxyethyl acrylate and 2-hydroxypropyl methacrylate. Both the first water-soluble monomer and the second water-soluble monomer have more hydrophilic groups such as -COOH, -OH, etc., and have greater solubility in water. On the one hand, the first water-soluble monomer and the second water-soluble monomer have more hydrophilic groups, and the hydrophilic groups can form hydrogen bonds with water molecules, which helps to improve the final high water absorption hydrogel product water absorption rate; on the other hand, aqueous solution polymerization is preferred for the preparation of hydrogel. In order to make the polymerization reaction uniform, the reacted monomer must have good solubility in water, that is, it must be a water-soluble monomer, otherwise it will affect the water coagulation. The final properties of the glue.

The initiator is one or more of ammonium persulfate, potassium persulfate and sodium persulfate. The initiator of free radical polymerization is a compound that is easy to decompose into free radicals. It has weak bonds in the structure, and its dissociation energy is 100-170kJ/mol, which is far lower than the C-C bond energy of 350kJ/mol. Most of the initiators are azo and peroxide. Oxygen compounds, such as azobisisobutyronitrile, azobisisoheptanonitrile, tert-butyl hydroperoxide, dicumyl peroxide, dibenzoyl peroxide, tert-butyl peroxybenzoate, peroxide Bicyclocarbonate dicarbonate, potassium persulfate, ammonium persulfate, etc. The selection of the initiator needs to be considered from many aspects such as polymerization method, polymerization temperature, influence on polymer properties and storage and transportation stability. The polymerization method is the primary basis. For the aqueous solution polymerization reaction of the present invention, a water-soluble initiator should be selected, such as one or more of potassium persulfate, ammonium persulfate, sodium persulfate, etc., which is beneficial to the aqueous solution polymerization of the present invention. The reaction proceeds.

The crosslinking agent is N, N'-methylenebisacrylamide, N, N'-methylenebismethacrylamide, polyethylene glycol diacrylate, polyethylene glycol dimethacrylate , ethylene glycol diacrylate, ethylene glycol dimethacrylate or one or more of them. The network structure of the hydrogel plays a decisive role in the water absorption performance, and the absorbed water is mainly bound inside the network structure. According to measurements, when the effective chain length of the grid is 10-9~10-8m, the hydrogel has the maximum water absorption rate. Generally, uncrosslinked hydrogels basically have no water absorption function, and after a small amount of crosslinking, the water absorption will increase sharply, but after reaching a certain level, it will decrease with the increase of crosslinking density. In order to improve the water absorption rate of the high water absorption rate hydrogel of the present invention, it is necessary to use a cross-linking agent, considering the water-absorbing effect of a strong hydrophilic group such as -COOH in the hydrogel, select the above-mentioned cross-linking agent for use, and The amount of the cross-linking agent is strictly limited so that the cross-linking density of the high water absorption hydrogel of the present invention can be kept in an appropriate range.

The present invention also provides a preparation method of a high water absorption hydrogel, based on polyvinyl alcohol, by means of grafting, block copolymerization-blending and IPN interpenetrating network polymerization, the method of solution polymerization is used to complete the high water absorption Preparation of hydrogels.

The preparation method of described high water absorption rate hydrogel comprises the steps:

Under the conditions of mechanical stirring and nitrogen protection, dissolve polyvinyl alcohol in part of water, add the first water-soluble monomer and part of the initiator, and react at 70°C to 80°C for 1h to 2h, then add the remaining water, the second After the water-soluble monomer, the remaining initiator and crosslinking agent, polymerize at 70°C-80°C for 2h-4h, then raise the temperature to 85°C-95°C, keep it warm for 0.5h-1.5h, then lower it to 15°C-35°C to obtain high Water absorption hydrogel.

The water-soluble monomer can be added twice, the first water-soluble monomer and the second water-soluble monomer added later can be selected from the same type or different types, such as the first water-soluble monomer is selected from methacrylic acid- 2-hydroxyethyl ester and acrylic acid, acrylic acid is selected as the second water-soluble monomer, and at this time, the water-soluble monomer is acrylic acid and methacrylic acid-2-hydroxyethyl ester.

The weight ratio of the part of the initiator to the rest of the initiator is 2-3:2, and the part of the initiator is divided into several equal parts and added intermittently for several times. More preferably, the part of the initiator is divided into 2 to 4 equal parts, and added in equal amounts intermittently every 25 minutes to 35 minutes.

The weight ratio of the partial water to the remaining water is 2-4:1; the weight ratio of the first water-soluble monomer to the second water-soluble monomer is 1:1.3-3.

The polymerization reaction is an exothermic reaction, and with the increase of the conversion rate of water-soluble monomer and the degree of polymerization, the viscosity of the whole reaction system will rise rapidly. If effective measures are not taken to control the reaction process, it will seriously affect the heat transfer, mass transfer and momentum transfer inside the system, and finally manifest as the deterioration of the appearance and performance of the product. Therefore, the polymerization reaction of the present invention is carried out in two steps, and at the same time, part of the initiator is divided into several equal parts, added intermittently for several times, and then adding the remaining initiator, which can well meet the needs of controlling the reaction process, thereby The prepared high water absorption rate hydrogel has high water absorption rate.

The water absorption test adopts the sieve method, take hydrogel m ₁ (about 1g, accurate to 0.001), vacuum-dry at 60°C to constant weight, and weigh to obtain m ₂ , the water content of hydrogel k=m ₁ /m ₂ ; take another hydrogel m ₃ (about 1g, accurate to 0.001), put it in pure water to fully absorb water and swell, sieve and filter water and weigh it to obtain m ₄ , then the water absorption k′ of the dry gel is

The film-forming test method: take 1 g of hydrogel, add 10 g to 50 g of water, keep stirring in an oil bath at 90 ° C to 110 ° C, and let it stand for 2 hours after becoming a liquid, and cast it on the glass coated with silicone oil Place it on a flat plate and dry it in an oven at 80°C to 120°C to obtain a film.

Compared with prior art, the present invention has following advantage:

The preparation method of the hydrogel provided by the present invention adopts the method of polymer chemical modification, at first utilizing copolymerization-blending to form a loose polymer network, and grafting and introducing hydrophilic groups (such as -COOH) on polyvinyl alcohol , -COONa, etc.), increase the polarity of the polyvinyl alcohol chain, improve the compatibility of the blend, and accelerate the water absorption rate; then use the interpenetrating polymer network (IPN) to make the original polymer network denser and improve the mechanical strength. At the same time, the hydrophilic monomers participating in the polymerization are evenly distributed in the hydrogel network, which helps to improve the water absorption rate and water absorption rate. The preparation method has the advantages of strong operability, good controllability, easy industrial implementation and the like.

The hydrogel with high water absorption rate prepared by the method of the invention not only has a higher water absorption rate, but also makes up for the shortcomings of low mechanical strength and difficult processing, and is easy to process to prepare a water-absorbing gel film.

Description of drawings

Fig. 1 is the comparative optical photo before and after the water absorption test of the high water absorption hydrogel prepared in Example 3, wherein (a) is the optical photo of the high water absorption hydrogel (water content k=4.5) prepared in Example 3 Photo, (b) is an optical photo of the high water absorption hydrogel prepared in Example 3 after the water absorption test (water absorption k'=304);

Fig. 2 is the optical photograph of the film formation of the high water absorption hydrogel prepared in Example 3.

Detailed ways

The present invention is described further in conjunction with embodiment.

Example 1

In a 250ml four-necked flask, add 60g of water and 4.8g of polyvinyl alcohol (PVA-124, the degree of polymerization is 2450, Shanghai Aladdin Company), start mechanical stirring, the time of nitrogen is 30min, and heat up to 80°C , add 1/5 amount of ammonium persulfate (ie 0.0338g, the total amount is 0.169g), 3.09g-2-hydroxyethyl methacrylate and 1.71g acrylic acid, then add 1/5 amount of persulfuric acid at intervals of 0.5h Ammonium (ie 0.0338g). After reacting for 1.5h (1/5 amount of ammonium persulfate was added 3 times, totaling 0.1014g), 30g of water, N,N'-methylenebisacrylamide (0.185g), 14.4g of acrylic acid (neutralized 0.7) and the remaining ammonium persulfate (ie 0.0676g), continue the reaction at 80°C for 2.5h, raise the temperature to 85°C, keep it warm for 1h and then lower it to 25°C to obtain a high water absorption hydrogel product.

Example 2

In a 250ml four-neck flask, add 60g of water and 4.8g of polyvinyl alcohol (PVA-124, the degree of polymerization is 2450, Shanghai Aladdin Co., Ltd.), start the mechanical stirring, the time of nitrogen is 30min, and heat up to 70°C , add 1/5 amount of ammonium persulfate (ie 0.0186g, the total amount is 0.093g), 3.09g-2-hydroxyethyl methacrylate and 1.71g acrylic acid, and then add 1/5 amount of persulfuric acid at intervals of 0.5h Ammonium (ie 0.0186 g). After reacting for 1.5h (1/5 amount of ammonium persulfate was added 3 times, totaling 0.0558g), 20g of water, N,N'-methylenebisacrylamide (0.0822g), 6.4g of acrylic acid (neutralized 0.7) and the remaining ammonium persulfate (ie 0.0372g), continue the reaction at 70°C for 2.5h, raise the temperature to 95°C, keep it warm for 0.5h and then lower it to 15°C to obtain a high water absorption hydrogel product.

Example 3

In a 250ml four-necked flask, add 60g of water and 4.8g of polyvinyl alcohol (PVA-124, the degree of polymerization is 2450, Shanghai Aladdin Co., Ltd.), start the mechanical stirring, the time of nitrogen is 30min, and heat up to 75°C , add 1/5 amount of ammonium persulfate (ie 0.0248g, the total amount is 0.124g), 3.09g 2-hydroxyethyl methacrylate and 1.71g acrylic acid, then add 1/5 amount of persulfuric acid at intervals of 0.5h Ammonium (ie 0.0248g). After reacting for 1.5h, add 25g of water, N,N`-methylenebisacrylamide (0.123g), 9.6g of acrylic acid (0.7 in neutralization degree) and the remaining ammonium persulfate (0.0496g), at 75°C Continue to react for 3 hours, raise the temperature to 85°C, keep it warm for 1 hour and then lower it to 35°C to obtain a high water absorption hydrogel product.

Example 4

In a 250ml four-necked flask, add 60g of water and 4.8g of polyvinyl alcohol (PVA-124, the degree of polymerization is 2450, Shanghai Aladdin Co., Ltd.), start the mechanical stirring, the time of nitrogen is 30min, and heat up to 75°C , add 1/5 amount of ammonium persulfate (ie 0.0111g, the total amount is 0.0555g), 3.09g 2-hydroxyethyl methacrylate and 1.71g methacrylic acid, and then add 1/5 amount of Ammonium persulfate (ie 0.0111 g). After reacting for 1.5h, add 20g of water, N, N'-methylene bisacrylamide (0.0308g in dosage), 2.4g of methacrylic acid (0.7 in neutralization degree) and remaining ammonium persulfate (0.0222g), in Continue to react at 75°C for 3 hours, raise the temperature to 85°C, keep it warm for 1 hour and then lower it to 25°C to obtain a high water absorption hydrogel product.

Example 5

In a 250ml four-necked flask, add 60g of water and 4.8g of polyvinyl alcohol (PVA-124, the degree of polymerization is 2450, Shanghai Aladdin Company), start mechanical stirring, the time of nitrogen is 30min, and heat up to 80°C , add 1/5 amount of ammonium persulfate (ie 0.0248g, the total amount is 0.124g) and 4.8g of 2-hydroxyethyl methacrylate, then add 1/5 amount of ammonium persulfate (ie 0.0248 g). After reacting for 1.5h, add 25g of water, N,N`-methylenebisacrylamide (0.123g), 9.6g of acrylamide and the remaining ammonium persulfate (0.0496g), continue the reaction at 80°C for 2.5h, and raise the temperature to 85°C, keep warm for 1.5 hours and then lower to 25°C to obtain a high water absorption hydrogel product.

Example 6

In a 250ml four-necked flask, add 60g of water and 4.8g of polyvinyl alcohol (PVA-124, the degree of polymerization is 2450, Shanghai Aladdin Company), start mechanical stirring, the time of nitrogen is 30min, and heat up to 80°C , add 1/5 amount of ammonium persulfate (that is, 0.0248g, the total amount is 0.124g), 3.09g of 2-hydroxypropyl methacrylate and 1.71g of acrylamide, and then add 1/5 of the amount of persulfate at intervals of 0.5h Ammonium sulfate (ie 0.0248g). Add 25g of water, N, N'-methylenebisacrylamide (amount of 0.123g), 9.6g of methacrylate-2-hydroxypropyl methacrylate and remaining ammonium persulfate (0.0496g) after reacting for 1.5h. Continue to react at ℃ for 2.5 hours, raise the temperature to 85 ℃, keep it warm for 1.5 hours and lower it to 25 ℃ to obtain a high water absorption hydrogel product.

Example 7

In a 250ml four-necked flask, add 60g of water and 4.8g of polyvinyl alcohol (PVA-124, the degree of polymerization is 2450, Shanghai Aladdin Company), start mechanical stirring, the time of nitrogen is 30min, and heat up to 80°C , add 3/5 amount of ammonium persulfate (3/5 amount of ammonium persulfate is added at one time, that is, 0.0744g, the total amount is 0.124g), 3.09g of 2-hydroxypropyl methacrylate and 1.71g of acrylamide After 1.5h of reaction, 25g of water, N, N'-methylenebisacrylamide (0.123g), 9.6g of 2-hydroxypropyl methacrylate and the remaining ammonium persulfate (0.0496g) were added. Continue to react at 80°C for 2.5 hours, raise the temperature to 85°C, keep it warm for 1.5 hours and then lower it to 25°C to obtain a high water absorption hydrogel product.

The high water absorption hydrogels prepared in Examples 1-7 were tested for water absorption by the screen method, and the specific method was as follows: take hydrogel m ₁ (about 1 g, accurate to 0.001), vacuum-dry at 60°C to constant weight, Weigh to obtain m ₂ , the water content of the hydrogel is k=m ₁ /m ₂ ; take another hydrogel m ₃ (about 1g, accurate to 0.001), put it in pure water to fully absorb water and swell, sieve and filter the water and weigh to obtain m ₄ , then the water absorption k` of the xerogel is

(a) in Fig. 1 is the optical photo of the high water absorption hydrogel (water content k=4.5) prepared in embodiment 3, (b) in Fig. 1 is the high water absorption hydrogel prepared in embodiment 3 after water absorption Optical photographs after testing (water absorption k'=304).

Film performance was tested by film formation: take 1 g of the high water absorption hydrogel prepared in Examples 1 to 7, add 30 g of water, and keep stirring in an oil bath at 100° C. After becoming liquid, let it stand for 2 hours, and drain it. Spread it on a glass plate coated with silicone oil, and dry it in an oven at 100°C to obtain a film. Fig. 2 is the optical photograph of the film formation of the high water absorption hydrogel prepared in Example 3.

The water absorption test data and membrane performance test data are shown in Table 1.

Table 1

For Example 4, the water absorption of the high water-absorbing hydrogel product prepared by it is low, mainly by the type of water-soluble monomer, the proportioning ratio of the first water-soluble monomer and the second water-soluble monomer, and the amount of initiator , the amount of cross-linking agent and other factors are jointly determined, especially the amount of cross-linking agent, which makes the cross-linking degree of the prepared high water absorption hydrogel product insufficient.

The difference between embodiment 6 and embodiment 7 lies in that: embodiment 6 adopts adding part of the initiator in 3 equal amounts, and embodiment 7 adopts adding part of the initiator at one time. It can be seen from Table 1 that compared with Example 7, the high water absorption hydrogel prepared in Example 7 has higher water absorption and better film-forming effect.

Claims (7)

1. the preparation method of an aquagel with high water absorbing capacity is characterized in that, comprises the steps:

Described aquagel with high water absorbing capacity is made by the raw material of following weight percent:

Described water-soluble monomer is comprised of the first water-soluble monomer and the second water-soluble monomer, and described the first water-soluble monomer and the second water-soluble monomer are identical or different, and the weight ratio of described the first water-soluble monomer and the second water-soluble monomer is 1:1.3～3;

Described linking agent is N, N ＇-methylene-bisacrylamide, N, one or more in N ＇-methylene-bis Methacrylamide, polyethyleneglycol diacrylate, polyethylene glycol dimethacrylate, glycol diacrylate, the ethylene glycol dimethacrylate;

Under mechanical stirring and nitrogen protection condition; polyvinyl alcohol is dissolved in the part water; add the first water-soluble monomer and part initiator; behind 70 ℃～80 ℃ lower reaction 1h～2h; after adding again residue water, the second water-soluble monomer, residue initiator and linking agent; behind 70 ℃～80 ℃ polymerization 2h～4h, be warming up to 85 ℃～95 ℃, be down to 15 ℃～35 ℃ behind insulation 0.5h～1.5h, obtain aquagel with high water absorbing capacity.

2. the preparation method of aquagel with high water absorbing capacity according to claim 1, it is characterized in that described the first water-soluble monomer is a kind of or two or more in vinylformic acid, methacrylic acid, acrylamide, 2-Hydroxy ethyl acrylate, 2-hydroxypropyl acrylate, methacrylic acid-2-hydroxy methacrylate, the methacrylic acid-2-hydroxy propyl ester;

Described the second water-soluble monomer is a kind of or two or more in vinylformic acid, methacrylic acid, acrylamide, 2-Hydroxy ethyl acrylate, 2-hydroxypropyl acrylate, methacrylic acid-2-hydroxy methacrylate, the methacrylic acid-2-hydroxy propyl ester.

3. the preparation method of aquagel with high water absorbing capacity according to claim 1 is characterized in that, described initiator is a kind of or two or more in ammonium persulphate, Potassium Persulphate, the Sodium Persulfate.

4. the preparation method of aquagel with high water absorbing capacity according to claim 1 is characterized in that, described part initiator is 2～3:2 with the weight ratio of residue initiator.

5. the preparation method of aquagel with high water absorbing capacity according to claim 1 is characterized in that, described part initiator is divided into some equivalent parts, intermittently adds several times.

6. the preparation method of aquagel with high water absorbing capacity according to claim 5 is characterized in that, described part initiator is divided into 2～4 equivalent parts, every intermittently equivalent adding of 25min～35min.

7. the preparation method of aquagel with high water absorbing capacity according to claim 1 is characterized in that, described part water is 2～4:1 with the weight ratio of residue water.

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