CN101062966A - Super water-absorbing resin and preparation method thereof - Google Patents

Abstract

The invention provides a superabsorbent resin and a preparation method thereof. The rubber emulsion added with a photoinitiator and a sensitizer is irradiated under ultraviolet light, and a dormant group is introduced on the surface of rubber particles, and then a crosslinking agent is added to the rubber emulsion. Heating until the dormant groups on the surface of the rubber particles break to generate surface free radicals, triggering the polymerization of the rubber emulsion with dormant groups on the surface of the rubber particles and the cross-linking agent to obtain a microscopic three-dimensional network of rubber composed of cross-linking agents and rubber particles Emulsion, adding a hydrophilic polymer monomer aqueous solution to the rubber emulsion, triggering the graft polymerization of the hydrophilic monomer, and preparing a star made of rubber particles as nodes and extending multiple water-absorbing molecular chains to the space. Microscopic three-dimensional cross-linked network structure water-absorbing resin composed of shaped water-absorbing units. The superabsorbent resin of the present invention has a water absorption rate of 5000 to 13000 times for pure water; for tap water with a hardness of 10, the water absorption rate reaches 350 to 650 times; The water absorption rate of %NaCl saline reaches 100-320 times.

Description

Super absorbent resin and its preparation method

Technical field:

The invention relates to a superabsorbent resin and a preparation method thereof, and relates to the technique of grafting polymerization on the surface of rubber latex particles initiated by ultraviolet light.

Background technique:

Superabsorbent resin refers to a hydrophilic polymer with a cross-linked network structure, which can absorb hundreds or even tens of thousands of times its own weight of water and maintain a gel state. Superabsorbent resin can be divided into the following two categories according to its composition, homopolymer superabsorbent resin: including polyacrylic acid (salt), polyacrylamide, polyethylene glycol, etc.; copolymer superabsorbent resin: including starch, cellulose system, protein-based graft superabsorbent resin, etc. From the perspective of microstructure, the existing superabsorbent resin mainly connects single molecular chains through cross-linking agent molecules, and the molecular chains are separated into several parts by cross-linking points (as shown in Figure 1). After being separated, the short hydrophilic molecular chains are greatly limited in their water absorption capacity. Therefore, the water absorption effect is not very high. Generally, the water absorption rate of pure water is about 800 to 2000 times, and the maximum water absorption rate of salt water (based on 0.9% sodium chloride (NaCl) solution by weight) is no more than 200 times. Therefore, An important content of superabsorbent resin preparation research is how to improve the water absorption ratio of superabsorbent resin. According to Flory's traditional water absorption formula of water-absorbent resin, it can be known that there are three main factors affecting the water absorption rate of superabsorbent resin: first, the hydrophilicity of the structural monomer of the superabsorbent resin itself, that is, the better the hydrophilicity of the monomer, the higher the superabsorbent. The higher the water absorption rate of the resin; second, the charge density in the super absorbent resin, the higher the charge density, the more discrete the molecular chains of the super absorbent resin, and the higher the water absorption rate; third, the crosslinking density of the super absorbent resin system , low cross-linking density, strong ability of molecular chains to move freely, and high water absorption rate.

At present, the preparation method of superabsorbent resin is generally obtained by adding monomer (or grafted main body), crosslinking agent and initiator into the reactor, and then polymerizing. The homopolymer superabsorbent resin is obtained by adding crosslinking agent and initiator to the monomer solution and polymerizing for a certain period of time. The copolymer superabsorbent resin is obtained by mixing pretreated starch (cellulose, protein, etc.) Then add cross-linking agent and initiator to polymerize. The difference between the different products obtained by polymerization by the above method lies in the selection and proportioning of monomers and crosslinking agents, but there is no ability to control the structure of the products.

The development space for improving the water absorption rate from the two aspects of monomer and charge density is very limited. The water absorption capacity of the water-absorbent resin is mainly controlled by the cross-linking density, which can be realized by two methods. The first is to adjust the amount of cross-linking agent. The second is to choose the type of crosslinking agent.

The water absorption rate of the superabsorbent resin has an inverse relationship with the amount of crosslinking agent. The more the amount of crosslinking agent is, the higher the crosslinking density is, and the lower the water absorption rate of the water absorbent resin is. In order to make the superabsorbent resin have a higher water absorption rate, the crosslink density must be reduced. However, if the cross-linking density is too low, the molecular chains of the superabsorbent resin will lack sufficient binding force to water, and the water absorption rate will decrease instead, and the gel content will also decrease. This is the root cause of the low water absorption capacity of traditional water-absorbent resins, thus restricting the further development of water-absorbent resins.

By selecting an appropriate cross-linking agent, the cross-link density can be reduced without changing the number of cross-link points, so as to improve the water absorption capacity. Chinese patent 01136626.5 discloses a method for synthesizing a macromolecular cross-linking agent, in which both ends of oligoethylene glycol with different molecular weights are esterified with acryloyl chloride to obtain cross-linking agents with different chain lengths. The cross-linking agent is used to prepare super-absorbent resin, which overcomes the problems of small molecular size and fast reaction of common cross-linking agents, which lead to uneven cross-linking of the water-absorbing resin, and obtains a water-absorbing resin with a water absorption rate of more than 4,000 times. In addition, the water absorption rate of the water-absorbent resin can also be controlled by controlling the chain length of the cross-linking agent, and the long-chain cross-linking agent can be used to reduce the cross-linking point density in the resin to increase the water absorption rate. At the same time, the cross-linking agent itself participates in water absorption, which is also conducive to the improvement of water absorption ratio. Nevertheless, the improvement of the water absorption rate of the patented resin is actually achieved by reducing the cross-linking density, which does not break through the traditional water-absorbing resin structure, and the cross-linking density cannot be reduced indefinitely, otherwise the cross-linking density is too low, which will inevitably lead to a loss of strength. Decrease and water absorption rate decrease.

The applicant discloses a kind of preparation method of ultraviolet light triggering cross-linking superfine powder rubber in Chinese patent application 200410046163x, will add the rubber latex of photoinitiator and cross-linking sensitizer to place the strength to be 30-100 watts/square Irradiation under ultraviolet light instead of gamma ray high-energy rays triggers rubber cross-linking.

Invention content:

The purpose of the present invention is to provide a superabsorbent resin with a new microstructure. The water-absorbent structure of the resin can make the water-absorbent resin have a longer water-absorbent chain, which has enough freedom to combine water molecules, and at the same time, the molecular chain is connected through the cross-linking structure. The water molecules combined on the surface are fixed, so it has a high water absorption rate. The present invention also provides a method for preparing the water-absorbing resin. Under the condition of ultraviolet light, a hydrogen abstraction type photoinitiator is used to form a dormant group on the surface of the rubber particles through a two-step reaction of initiation-coupling, and then use the dormant group to initiate Hydrophilic monomers are polymerized, and water-absorbent polymers are grafted to prepare superabsorbent resins with a new structure and high water absorption rate.

The superabsorbent resin of the present invention is composed of rubber particles in a three-dimensional space network structure grafted with water-absorbing polymers, and each rubber particle in the network structure is used as a node to extend a plurality of water-absorbing and water-absorbing polymers into the space. The high molecular polymer molecular chains that store water form a water-absorbing unit in a star-shaped structure.

The above-mentioned water-absorbing high molecular polymer is a high molecular polymer obtained by polymerizing acrylic acid, acrylamide and its derivatives, acrylic ester or/and other common vinyl monomers.

The preparation method of the superabsorbent resin of the present invention comprises the following steps in turn: irradiating the rubber emulsion added with a photoinitiator and a sensitizer under ultraviolet light and under the protection of an inert gas, and reacting for 15 to 90 minutes, through two steps of initiation-coupling The reaction introduces dormant groups on the surface of rubber particles; adds a crosslinking agent to the irradiated rubber emulsion, heats to 75-90°C to break the dormant groups on the surface of rubber particles to generate surface free radicals, and then heats them at a temperature of 75-90 Stir the reaction at ℃, the reaction time is 0.5 hours to 2 hours, initiate the polymerization reaction of the rubber emulsion with dormant groups on the surface of the rubber particles and the cross-linking agent, and obtain the cross-linked rubber with a microscopic three-dimensional network composed of the cross-linking agent and rubber particles Emulsion, in which the network uses colloidal particles as nodes and cross-linking agent molecular chains as network lines; add hydrophilic monomer aqueous solution to the cross-linked rubber emulsion, and carry out grafting reaction at a temperature of 75-90 °C. The time is 4 to 20 hours. The unreacted dormant groups on the surface of the rubber particles are broken to generate primary free radicals to initiate the grafting reaction of the hydrophilic monomers, forming multiple hydrophilic polymer molecular chains extending from the surface of the rubber particles to the space. , forming a water-absorbing unit similar to a star-shaped structure, and obtaining a new structure of superabsorbent resin.

In the above method, the photoinitiator is the same as the hydrogen abstraction type ultraviolet photoinitiator disclosed in the patent application 200410046163x, such as: benzophenone and its derivatives, anthraquinone and its derivatives, thioxanthone and its derivatives or oxa Anthrone and its derivatives; the photoinitiator is used in an amount of 0.5-5% of the dry rubber, preferably 3-5%.

The sensitizer used in the above method, as disclosed in the patent application 200410046163x, is a monofunctional, difunctional or multifunctional polymerizable monomer or a mixture of multiple polymerizable monomers. The dosage is 1-5% of dry rubber by mass. Mixed use of monofunctional and multifunctional sensitizers can achieve better results.

In the above method, the irradiation intensity of ultraviolet light is 30-100 W/m ² , and the suitable wavelength is 230-400 nm.

In the above method, the cross-linking agent added in the rubber emulsion after irradiation is a bisacrylamide water-soluble diene compound; the consumption of the cross-linking agent is 1 to 9% of the dry rubber mass percentage, and the preferred amount is 1-5% of the mass percentage.

The hydrophilic monomers used in the above method are common: acrylic acid and its derivatives, acrylamides and their derivatives, acrylates and their derivatives or/and other vinyl hydrophilic monomers; monomer amount It is 15 to 60 times the weight of rubber dry glue.

Effects of the present invention: The present invention constructs a water-absorbing unit with a new microscopic star-shaped structure by grafting water-absorbing polymers with rubber particles of a three-dimensional space network structure. The water-absorbing structure has a longer water-absorbing chain and has sufficient freedom It can combine water molecules, and at the same time, the three-dimensional cross-linking structure of the network space fixes the water molecules combined on the molecular chain, thereby greatly improving the water absorption rate of the water-absorbent resin. The water absorption rate of the super-absorbent resin of the present invention can reach 5000-13000 times, more preferably 5000-10000 times; for tap water with a hardness of 10, the water absorption rate can reach 350-650 times, more preferably 350-500 times; The magnification can reach 100-320 times, more preferably 100-250 times, which is much higher than the water absorption rate of general water-absorbing resins.

Description of drawings:

Figure 1 is a schematic diagram of the microstructure of the water-absorbing unit of the existing water-absorbent resin; in the figure, 1 is a single molecular chain, and 2 is a cross-linking agent molecule.

Fig. 2 is a schematic diagram of the microscopic star-shaped structure of the water-absorbing resin water-absorbing unit of the present invention; in the figure, 3 represents the rubber colloidal node, and 4 is the polymer water-absorbing chain

Fig. 3, Fig. 4 are the initiation and the coupling process schematic diagram that the preparation method of the present invention introduces the retriggerable dormant group on the surface of the rubber colloid;

Fig. 5 is a schematic diagram of the process of preparing a rubber emulsion with a microscopic three-dimensional network structure by reacting a rubber emulsion containing a dormant group and a crosslinking agent in the preparation method of the present invention;

Fig. 6 is a schematic diagram of the reaction process of the preparation method of the present invention initiating the grafting reaction of hydrophilic monomers on the nodes of the emulsion micro-network to prepare superabsorbent resins; in the figure, 3 represents the nodes of rubber particles, 4 represents the polymer water-absorbing chain, and 5 represents Three-dimensional cross-linked structure in network space.

Detailed ways:

Starting from the microstructure of the water-absorbing resin, the present invention first constructs a space network of rubber particles, and on the basis of the aforementioned ultraviolet light-induced crosslinking rubber technology, grafts a hydrophilic polymer on the surface of the rubber particles to obtain a novel structure and A water-absorbent resin that exhibits a super high water absorption capacity. The implementation method is as follows:

The first step: introducing reinitiative dormant groups on the surface of rubber particles: irradiating the rubber emulsion with added photoinitiator and sensitizer under ultraviolet light, and introducing dormant groups on the surface of rubber particles. Taking the hydrogen abstraction type photoinitiator benzophenone (BP) as an example, the semi-inhalol dormant group can be introduced on the surface of rubber particles through the initiation-coupling two-step reaction as shown in Figure 3 and Figure 4. Under the action of light or heat, the weak bond between the dormant group and the surface of rubber particles can be broken to regenerate free radicals to initiate polymerization. The specific method is: first dissolve the photoinitiator in the sensitizer to prepare a mixed solution of the photoinitiator and the sensitizer; add the rubber emulsion into the reactor with stirring, and add the photoinitiator and sensitizer dropwise while stirring. The mixed solution of the reagent; after it is completely dissolved, pass nitrogen to remove oxygen for at least 30 minutes, keep stirring, and then place the above-mentioned prepared reaction solution under ultraviolet light for 15 to 90 minutes under the protection of nitrogen to react.

The radiation light source used in the method of the present invention is the radiation light source commonly used in the UV-induced polymerization technology, including mercury arc lamps (including low-pressure mercury lamps, medium-pressure mercury lamps and high-pressure mercury lamps), electrodeless lamps or metal halide lamps. The suitable wavelength of the ultraviolet light used is 230-400 nm, and the irradiation intensity is 30-100 W/m ² . The reactor is a closed container, and the light transmittance of the part of the reactor facing the light source is required to be greater than 80%. It is generally made of light-transmitting materials, such as hard glass, quartz glass, resin film (such as polyethylene film, polypropylene film or polyester film), etc.

The rubber emulsion used in the present invention can be a kind of rubber or a mixed rubber emulsion of multiple rubbers; the rubber emulsion can be in solution, emulsion, or fine suspension; The solid content is 40-60% by weight, generally 50% by weight, and the particle size of rubber colloids is generally about 50-500nm.

The photoinitiator used is a hydrogen abstraction type ultraviolet photoinitiator, which can be benzophenone (BP) and its derivatives, anthraquinone and its derivatives, thioxanthone (commonly used as isopropylthioxanthone -ITX, etc.) or xanthones and their derivatives, etc. The amount of the photoinitiator is generally 0.5-5% (mass percentage) of the dry rubber, preferably 3-5%.

The sensitizer used is, for example, a monofunctional, difunctional or multifunctional polymerizable monomer or a mixture of multiple polymerizable monomers disclosed in patent application 200410046163x. Mixed use of monofunctional and multifunctional sensitizers can achieve better results. The monofunctional sensitizer is selected from butyl acrylate, octyl methacrylate, isooctyl methacrylate or glycidyl methacrylate, etc.; the bifunctional sensitizer is selected from butylene glycol dimethacrylate, Hexylene glycol dimethacrylate, ethylene glycol dimethacrylate or triethylene glycol dimethacrylate, etc.; the multifunctional sensitizer is selected from trimethylolpropane triacrylate (TMPTA), Trimethylolpropane trimethacrylate, pentaerythritol trimethacrylate, pentaerythritol tetramethacrylate, and the like. The sensitizer mainly has two functions: firstly, the sensitizer can dissolve the solid photoinitiator, so that the initiator can be brought to the surface and inside of the rubber particle; Hydrogen produces dormant groups, and active hydrogen can also be captured from the interior of latex particles to generate dormant groups through the bridging effect of sensitizers. The existence of the sensitizer increases the content of dormant groups on the surface and inside of latex particles, which is beneficial to further crosslinking and grafting reactions.

The dosage of the sensitizer is generally 1-5% (mass percentage) of the dry rubber, preferably 3-5%.

In this step, it is better to adopt different light time for different photoinitiators. For BP photoinitiators, the light time is preferably 60 to 90 minutes; for ITX photoinitiators, the light time is preferably 15 to 30 minutes. If the light time is too short, the photoinitiator cannot be fully initiated, and the requirement for secondary initiation cannot be met. If the illumination time is too long, the dormant groups obtained will be consumed under the action of light, which is not conducive to the subsequent reaction and consumes more energy.

The second step: prepare a rubber emulsion with a microscopic three-dimensional network structure: that is, add a crosslinking agent to the rubber emulsion obtained in the first step, heat it to a certain temperature, and break the dormant group on the surface of the rubber particles to generate surface free radicals, and then initiate crosslinking. Linking agent polymerization (as shown in Figure 5), the obtained emulsion is composed of a microscopic three-dimensional network composed of crosslinking agent and rubber particles. The network uses the particles as nodes and the molecular chain of the crosslinking agent as network lines.

The specific method is: take a certain amount of the emulsion obtained in the first step above, dilute it with water, add a certain amount of cross-linking agent aqueous solution, and react at a certain temperature after deoxygenating with nitrogen for at least 30 minutes. The reaction temperature is 75-90°C, and the reaction time is 0.5-2 hours.

The crosslinking agent used in this step is a water-soluble diene compound, which can be bisacrylamide, such as N, N-methylene-bisacrylamide (MBA), piperazine bisacrylamide, etc., and the amount of crosslinking agent is general It is 1-10% (mass percentage) of rubber dry glue.

The third step: Initiate the grafting reaction of hydrophilic monomers on the colloidal nodes of the microscopic network of the emulsion to prepare superabsorbent resin: as shown in Figure 6, the unreacted dormant groups on the surface of the colloidal particles are formed on the microscopic network nodes obtained in the second step. The group breaks to generate primary free radicals, triggers the grafting reaction of hydrophilic monomers to prepare superabsorbent resins, and the formed hydrophilic polymer molecular chains extend from the surface of the rubber particles to the space, and the structural units are similar to star structures (see Figure 2) . Finally, a superabsorbent resin with a microscopic three-dimensional cross-linked network structure consisting of star-shaped water-absorbing units extending out multiple water-absorbing molecular chains to the space is obtained.

The specific method is: take a certain amount of the rubber emulsion obtained in the second step and add it to the reaction bottle, then add the aqueous solution of the hydrophilic monomer and mix evenly, pass nitrogen to remove oxygen for at least 30 minutes, and then heat up to a certain temperature for grafting reaction. The grafting reaction time is 4-24 hours, and the reaction temperature is 75-90°C.

The hydrophilic monomers used are generally known water-soluble ethylenic monomers, acrylic acid and its derivatives, acrylamide and its derivatives, acrylate and its derivatives or/and other vinyl hydrophilic monomers, such as: acrylamide N-alkyl derivatives of 2-acrylamido-2-methyl-1-propanesulfonic acid; 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, N-vinylpyrrolidone, allyl Phosphonic acids, sulfuric acids, sulfonic acids, etc.

The above-mentioned hydrophilic monomers can be used alone, or several kinds can be used in combination, and the amount of the monomers used is 15 to 60 times the weight of the dry rubber.

The measuring method of monomer transformation rate and gel content in the inventive method is as follows:

Take three pieces of prepared super absorbent resin, weigh them as W ₁ , W ₂ , and W ₃ respectively, and dry the first part of the super absorbent resin directly to constant weight (the drying process adopted in the present invention is: firstly dry at 50°C under normal pressure 24 hours, and then vacuum-dried at 50°C for 24 hours), and the weight was weighed as W ₄ ; the second part of the water-absorbent resin was soaked in acetone for 5 days, and the acetone was changed every 12 hours to remove unreacted monomers and retain the polymerization and then dried to constant weight, and the weight was weighed as W ₅ ; the third part of the water-absorbent resin was soaked in water for 72 hours, and the water was changed every 6 hours to remove the non-grafted part. Then dry to constant weight, and weigh to get the weight W ₆ . Conversion rate and gel content are calculated according to the following formula:

In the formula: W ₄ /W ₁ is the total amount of monomer added per gram of sample; W ₅ /W ₂ is the total amount of polymer per gram of sample; W ₆ /W ₃ is the total amount of gel.

The assay method of water absorption capacity in the inventive method is as follows:

1. Water absorption ratio of pure water: Take a small piece of super absorbent resin and soak it in three-distilled ultrapure water, change the water every 12 hours, soak for 5 days, take out a certain amount of super absorbent resin and weigh it as W ₇ , and then dry the superabsorbent resin at 50°C for 24 hours, then vacuum-dry it at 50°C for 24 hours, and weigh W ₈ . The water absorption ratio is calculated according to the following formula:

2. The water absorption rate of tap water and salt water: Take a small piece of super absorbent resin and soak it in tap water or 0.9% NaCl brine, change the water every 12 hours, soak for 5 days, take out a certain amount of super absorbent resin and weigh W ₉ , and then soak the gel in pure water, change the water every 12 hours, and soak for 5 days. Then dry at 50°C for 24 hours, then vacuum-dry at 50°C for 24 hours, take out and weigh W ₁₀ , and the ratio of absorbing tap water (salt water) is calculated according to the following formula:

The implementation of the present invention is further described by the following examples, but the present invention should not be limited to these examples, and should also include: without departing from the scope of the present invention, the disclosed method is carried out various changes obvious to those skilled in the art.

Example 1

Add 5g of photoinitiator benzophenone (BP) to 4g of sensitizer trimethylolpropane triacrylate (TMPTA) and 1g of n-butyl acrylate (n-BA), TMPTA and n-BA by mass The ratio of 4:1 is used together; the initiator is added to the sensitizer to dissolve it completely.

200g of nitrile rubber emulsion (100g of dry glue weight, product code: nitrile 26) is placed in a beaker, stirred, and the mixed solution of the photoinitiator and sensitizer prepared above is added dropwise to make it in the rubber Dissolves completely in emulsion.

Take 20ml of the above-mentioned prepared nitrile rubber emulsion and place it in a light reaction bottle, pass nitrogen for 30 minutes, and place it under ultraviolet light for light. The light source is a high-pressure halogen lamp, the intensity of the main wavelength light is 40 watts/square meter, the initiator absorbs the wavelength range, and the light time is 90 minutes to obtain a pre-polymerized emulsion.

Take 2 g of the above-mentioned prepolymer emulsion, 0.04 g of N,N-methylenebisacrylamide (MBA) and dissolve it in 98 g of water, pass nitrogen gas for 30 minutes, and react in a water bath at 85° C. for 120 minutes to obtain a reaction emulsion.

Take 10g of the above-mentioned reaction emulsion, mix it with 5g of water, 9g of 30% acrylamide (AM), and 6g of 5% acrylic acid (AA) in a reaction bottle, and the total monomer concentration is 10% by weight. Nitrogen was blown for 30 minutes, and the reaction was carried out in a water bath at 85° C. for 10 hours to obtain the product superabsorbent resin. After measurement, the monomer conversion rate is 60%, the gel content is 87.2%, the absorption rate of pure water is 6900 times, the absorption rate of tap water is 650 times, and the absorption rate of 0.9% saline is 138 times.

Example 2

The preparation method is the same as in Example 1, except that the reaction temperature in the last step of polymerization is lowered to 80° C., and the reaction time is extended to 20 hours. The product superabsorbent resin is determined to have a monomer conversion rate of 87.3%, a gel content of 98.7%, an absorption rate of 6,000 times for pure water, 500 times for tap water, and 184 times for 0.9% saline.

Example 3

The preparation method is the same as in Example 1, except that the reaction time is shortened to 4 hours during the last step of polymerization. The product superabsorbent resin is determined to have a monomer conversion rate of 54.64%, an absorption rate of 12,500 times for pure water, 610 times for tap water, and 246 times for 0.9% salt water.

Example 4

The preparation method is as in Example 1, and the reaction emulsion of Example 1 is still used. Take 10g of the reaction emulsion, mix it with 2.5g of water, 8.5g of 30% acrylamide (AM), and 9g of 5% acrylic acid (AA) in a reaction flask, and the total monomer concentration is 10% by weight. Nitrogen was blown for 30 minutes, and the reaction was carried out in a water bath at 85° C. for 10 hours to obtain the product superabsorbent resin. It has been determined that the absorption rate of pure water is 7500 times.

Example 5

Take 1 g of the prepolymer emulsion in Example 1, and dissolve 0.02 g of N, N-methylenebisacrylamide (MBA) in 98 g of water, pass nitrogen gas for 30 minutes, and react in a water bath at 85° C. for 60 minutes to obtain a reaction emulsion.

Take 10g of the above reaction emulsion, mix it with 5.35g of water, 8.5g of 30% acrylamide (AM), 6g of 5% acrylic acid (AA), and 0.15g of N-vinylpyrrolidone (NVP) in a reaction flask. The concentration is 10% by weight. Nitrogen was blown for 30 minutes, and the reaction was carried out in an 80° C. water bath for 10 hours to obtain the product superabsorbent resin. The measured monomer conversion rate is 74.5%, the gel content is 96.9%, the absorption rate to pure water is 5000 times, the absorption rate to tap water is 550 times, and the absorption rate to 0.9% saline is 200 times.

Example 6

The preparation method was the same as in Example 5. The amount of N,N-methylenebisacrylamide (MBA) was reduced to 0.01 g, nitrogen gas was passed for 30 minutes, and the reaction was carried out in a water bath at 85° C. for 60 minutes to obtain a reaction emulsion.

Take 10g of the above-mentioned reaction emulsion, 8g of 30% acrylamide (AM), and 12g of 5% acrylic acid (AA) in a reaction bottle and mix them. The total monomer concentration is 10% by weight. Nitrogen was blown for 30 minutes, and the reaction was carried out in a water bath at 85° C. for 10 hours to obtain the product superabsorbent resin. It is determined that the monomer conversion rate is 75.4%, the gel content is 74.56%, the absorption rate for pure water is 6000 times, and the absorption rate for 0.9% saline is 300 times.

Example 7

With 5g photoinitiator benzophenone (BP), add in 4g sensitizer TMPTA and 1g n-butyl acrylate (n-BA), TMPTA and n-BA are used in conjunction with the ratio of 4: 1 by mass ratio; The initiator is added to the sensitizer to dissolve it completely.

200g carboxylated nitrile rubber emulsion (dry rubber weight 100g) is placed in a beaker, stirred, and gradually added the mixed solution of the photoinitiator and sensitizer prepared above, so that it is completely dissolved in the rubber emulsion.

Take 20ml of the above-mentioned prepared nitrile rubber emulsion and place it in a light reaction bottle, pass nitrogen for 30 minutes, and place it under ultraviolet light for light. The light source is a high-pressure halogen lamp, the intensity of the main wavelength light is 45 watts/square meter, the initiator absorbs the wavelength range, and the light time is 60 minutes to obtain a pre-polymerized emulsion.

Take 3 g of the above-mentioned prepolymer emulsion, 0.06 g of N, N-methylenebisacrylamide (MBA) and dissolve it in 147 g of water, pass nitrogen gas for 30 minutes, and react in a water bath at 85 ° C for 60 minutes to obtain a reaction emulsion.

Take 10g of the above-mentioned reaction emulsion, mix it with 10g of water, 9.3g of 30% acrylamide (AM), and 0.7g of 30% acrylic acid (AA) in a reaction bottle, and the total monomer concentration is 10% by weight. Nitrogen was blown for 30 minutes, and the reaction was carried out in a water bath at 85° C. for 10 hours to obtain the product superabsorbent resin. The measured conversion rate is 66.39%, the gel content is 85.78%, the absorption rate for pure water is 8900 times, the absorption rate for tap water is 540 times, and the absorption rate for 0.9% saline is 164 times.

Example 8

The preparation method was the same as in Example 7, only the reaction temperature during crosslinking and polymerization was increased to 90° C., and the reaction time was 8 hours. The product superabsorbent resin is determined to have a monomer conversion rate of 64.74% and an absorption rate of 13,000 times for pure water.

Example 9

The implementation method is the same as in Example 7, only after the product obtained in Example 7 is fully soaked in pure water, soak and hydrolyze with 0.5% sodium hydroxide solution, after the hydrolysis time is 18 hours, the absorption rate of pure water increases to 8000 times, when the hydrolysis time is 106 hours, the absorption rate of pure water reaches 10060 times.

Example 10

The implementation method is the same as in Example 7, except that 30% acrylamide (AM) in Example 7 is reduced to 9g, and 30% acrylic acid (AA) is increased to 1g, and placed in a reaction flask for mixing, and the total monomer concentration is 10% by weight. Nitrogen was blown for 30 minutes, and the reaction was carried out in a water bath at 85° C. for 10 hours to obtain the product superabsorbent resin. After measurement, the monomer conversion rate is 61.54%, the gel content is 88.36%, the absorption rate to pure water is 13000 times, the absorption rate to tap water is 560 times, and the absorption rate to 0.9% saline is 204 times.

Example 11

Implementation method is the same as in Example 7, only 30% acrylamide (AM) in Example 7 is reduced to 8.8g, and 0.15g of 2-hydroxyethyl methacrylate (HEMA) is added simultaneously, mixed in a reaction bottle, adjusted with water The total monomer concentration is 10% by weight. Nitrogen was blown for 30 minutes, and the reaction was carried out in a water bath at 85° C. for 10 hours to obtain the product superabsorbent resin. After measurement, the monomer conversion rate is 73.64%, the gel content is 88.41%, the absorption rate to pure water is 5000 times, the absorption rate to tap water is 350 times, and the absorption rate to 0.9% saline is 129 times.

Example 12

Get 6g of the pre-polyemulsion used in Example 7, 0.135g N, N-methylenebisacrylamide (MBA) was dissolved in 147g water, nitrogen was passed for 30 minutes, and reacted in a water bath at 85°C for 60 minutes to obtain a reaction emulsion.

Take 10g of the above-mentioned reaction emulsion, mix it with 10g of water, 9g of 30% acrylamide (AM), and 1g of 30% acrylic acid (AA) in a reaction flask, and the total monomer concentration is 10% by weight. Nitrogen was blown for 30 minutes, and the reaction was carried out in a water bath at 85° C. for 10 hours to obtain the product superabsorbent resin. It has been determined that the absorption rate for pure water is 7000 times, the absorption rate for tap water is 357 times, and the absorption rate for 0.9% salt water is 161 times.

Example 13

The implementation method is the same as in Example 10, only the gel product in Example 10 is cut into small pieces, and hydrolyzed with solid sodium hydroxide for 24 hours to obtain the hydrolyzed gel. It has been determined that the absorption rate for pure water is 10100 times, and the absorption rate for 0.9% salt water is 321 times.

Example 14

Add 0.5g of photoinitiator isopropylthioxanthone (ITX) to 4g of sensitizer TMPTA and 1g of n-butyl acrylate (n-BA), TMPTA and n-BA in a mass ratio of 4:1 Use in conjunction; add the initiator to the sensitizer to dissolve it completely.

200g carboxylated nitrile rubber emulsion (dry rubber weight 100g) is placed in a beaker, stirred, and gradually added the mixed solution of the photoinitiator and sensitizer prepared above, so that it is completely dissolved in the rubber emulsion.

Take 20ml of the above-mentioned prepared nitrile rubber emulsion and place it in a light reaction bottle, pass nitrogen for 30 minutes, and place it under ultraviolet light for light. The light source is a high-pressure halogen lamp, the intensity of the main wavelength light is 45 watts/square meter, the initiator absorbs the wavelength range, and the light time is 15 minutes to obtain a pre-polymerized emulsion.

Take 3 g of the above-mentioned prepolymer emulsion, 0.06 g of N, N-methylenebisacrylamide (MBA) and dissolve it in 147 g of water, pass nitrogen gas for 30 minutes, and react in a 75°C water bath for 30 minutes to obtain a reaction emulsion.

Take 10g of the above-mentioned reaction emulsion, mix it with 10g of water, 9.3g of 30% acrylamide (AM), and 0.7g of 30% acrylic acid (AA) in a reaction bottle, and the total monomer concentration is 10% by weight. Nitrogen was blown for 30 minutes, and the reaction was carried out in a water bath at 75° C. for 10 hours to obtain the product superabsorbent resin. The measured conversion rate is 55.28%, the absorption rate for pure water is 8100 times, the absorption rate for tap water is 500 times, and the absorption rate for 0.9% salt water is 295 times.

Example 15

Add 0.5g of photoinitiator isopropylthioxanthone (ITX) to 4g of sensitizer TMPTA and 1g of n-butyl acrylate (n-BA), TMPTA and n-BA in a mass ratio of 4:1 Use in conjunction; add the initiator to the sensitizer to dissolve it completely.

200g styrene-butadiene rubber emulsion (dry rubber weight 100g) is placed in a beaker, stirred, and the mixed solution of the above-mentioned prepared photoinitiator and sensitizer is gradually added to make it dissolve completely in the rubber emulsion.

Take 50ml of the above-prepared styrene-butadiene rubber emulsion and place it in an illumination reaction bottle, pass nitrogen for 30 minutes, and place it under ultraviolet light for illumination. The light source is a high-pressure halogen lamp, the intensity of the main wavelength light is 45 watts/square meter, the initiator absorbs the wavelength range, and the illumination time is 30 minutes to obtain a pre-polymerized emulsion.

Take 2 g of the above-mentioned prepolymer emulsion, 0.04 g of N, N-methylenebisacrylamide (MBA) and dissolve it in 98 g of water, pass nitrogen gas for 30 minutes, and react in a water bath at 85 ° C for 60 minutes to obtain a reaction emulsion.

Take 10g of the above-mentioned reaction emulsion, mix it with 10g of water, 9g of 30% acrylamide (AM), and 1g of 30% acrylic acid (AA) in a reaction flask, and the total monomer concentration is 10% by weight. Nitrogen was blown for 30 minutes, and the reaction was carried out in a water bath at 85° C. for 10 hours to obtain the product superabsorbent resin. The measured conversion rate is 76.93%, the gel content is 84.91%, the absorption rate for pure water is 9400 times, the absorption rate for tap water is 350 times, and the absorption rate for 0.9% saline is 120 times.

Claims (10)

1, a kind of super moisture absorbing resin, it is characterized in that: constitute by the rubber micelle grafting suction high molecular polymer that is the solid space network structure, each rubber micelle in the network structure is a node, stretch out a plurality of can the suction and the suction high molecular polymer molecular chain of water storage to the space, form the suction unit that is star structure.

2, the preparation method of the described super moisture absorbing resin of a kind of claim 1, may further comprise the steps successively: will add the rubber latex of light trigger and sensitizing agent under UV-light, under protection of inert gas, shine, reacted 15～90 minutes, and introduced the dormancy group on rubber micelle surface by initiation-coupling two-step reaction; In postradiation rubber latex, add linking agent, being heated to 75～90 ℃ makes the dormancy base fracture on rubber micelle surface produce surface free radical, stirring reaction 0.5～2 hour, cause rubber latex and linking agent polyreaction that the micelle surface has the dormancy group, obtain the rubber latex of the microcosmic cubic network that constitutes by linking agent and rubber micelle; Add the hydrophilic monomer aqueous solution in the microcosmic cubic network rubber latex of gained, carry out graft reaction under 75～90 ℃ of temperature, the graft reaction time is 4～20 hours.

3, preparation method according to claim 2 is characterized in that, used light trigger is the hydrogen-abstraction ultraviolet initiator, and consumption is 0.5～5% of a rubber dry glue quality per-cent; Used sensitizing agent is a kind of polymerisable monomer of single functionality, difunctionality or polyfunctionality or the mixture of multiple polymerisable monomer, and consumption is 1～5% of a rubber dry glue quality per-cent.

4, preparation method according to claim 3 is characterized in that, the hydrogen-abstraction ultraviolet initiator is benzophenone and derivative thereof, anthraquinone and derivative thereof, thioxanthone and derivative thereof or xanthone and derivative thereof.

5, preparation method according to claim 2 is characterized in that, adding linking agent in postradiation rubber latex is water-soluble double vinyl compound.

6, preparation method according to claim 5 is characterized in that, water-soluble double vinyl compound is: N, N-methylene radical-bisacrylamide or piperazine diacrylamine.

7, preparation method according to claim 2 is characterized in that, the consumption of linking agent is the mass percent 1～9% of the dried glue of rubber.

8, preparation method according to claim 2 is characterized in that, used hydrophilic monomer is: vinylformic acid and derivative thereof, acrylamide and derivative thereof, its derivative of acrylate are or/and other vinyl hydrophilic monomer; Amount of monomer is 15～60 times of the dried glue weight of rubber.

9, preparation method according to claim 2, it is characterized in that used hydrophilic monomer is to be selected from one or more of following material: the N-alkyl derivative of (methyl) vinylformic acid, (methyl) acrylamide, (methyl) acrylamide, 2-acrylamido-2-methyl isophthalic acid-propanesulfonic acid; Vinylformic acid 2-hydroxy methacrylate, 2-hydroxyethyl methacrylate; The N-vinyl pyrrolidone, allylic phosphonic acid based, sulfuric acid based, sulfonic acid class.

10, preparation method according to claim 2 is characterized in that, for the benzophenone photoinitiator, and light application time 60～90 minutes; For thioxanthone photoinitiator, light application time 15～30 minutes.

Images