WO2016179842A1 - Acrylic water absorbent resin with high liquid absorption rate and preparation method and use thereof - Google Patents

Abstract

Provided are an acrylic water absorbent resin with a high liquid absorption rate and a preparation method and a use thereof. The raw materials for preparing the acrylic water absorbent resin comprise acrylic acid, a base and water in a mass ratio of (25-45) : (7-22) : (33-68), and 0.001 wt%-1 wt% of a cross-linking agent, 0.01 wt%-2 wt% of a high-temperature resistant foaming agent, 0-10 wt% of a comonomer, 30 ppm-500 ppm of a reductant, and 0.001 wt%-1 wt% of an initiator, based on the mass of the acrylic acid. The liquid absorption rate of the acrylic water absorbent resin is 15 s-40 s. The water absorbent resin can be used as a liquid absorbent material in paper diapers, baby diaper pads, sanitary napkins and the like in the hygiene industry, and also can be used as a water absorbent and water retaining material in desertification control, water shutoff in oil field, agriculture and forestry water retention and other industries.

Description

Acrylic water absorbing resin with high liquid absorption rate, preparation method and use thereof Technical field

The present invention relates to the field of chemical engineering, and more particularly to a water absorbing resin having a high liquid absorption rate, a preparation method thereof and use thereof.

Background technique

The superabsorbent resin is a crosslinked network polymer containing a large number of strongly polar groups, which was first obtained by Fanta et al. using starch grafted polyacrylonitrile and then saponified. Since the 1960s, superabsorbent resins have been developed globally, and can be divided into two categories according to raw materials: the first is natural polymers such as starch and cellulose; the second is synthetic polymers such as poly. Acrylic acid, polyoxyethylene, polyvinyl alcohol, in which more than 80% of the super absorbent resin is currently polymerized from acrylic monomers. Since the crosslinked acrylic water absorbing resin has a network structure, it can absorb hundreds of times or even thousands of times of pure water of its own mass, and locks moisture without seeping out. Therefore, acrylic water absorbing resin is widely used in the sanitary industry such as baby diapers and diapers, and also has some applications in industries such as agriculture and forestry water conservation, desert management, and oil field water shutoff.

The hygienic industry has very high requirements for the performance of acrylic water-absorbing resin. One of them is the liquid absorption rate, which requires the diaper to absorb the baby or adult urine in a short time, and only the acrylic water-absorbing resin with high liquid absorption rate can meet this requirement. . In order to increase the liquid absorption rate, the general principle is to increase the specific surface area of the water absorbing resin by: (1) adding a porogen to decompose and release a gas during the reaction, such as sodium hydrogencarbonate or azobisisobutyronitrile. (2) adding a low-boiling liquid, which is susceptible to heat vaporization during the reaction, such as ethanol, n-propanol, and the like. However, due to the exothermic heat of acrylic acid, the temperature of the system is high. Under this condition, the bubbles generated by the first method are difficult to exist stably, and are easily aggregated and broken at high temperatures. The pores formed by the second method are limited because of the polymerization process. The large amount of moisture volatilizes, leaving large pores in the gel instead of tiny pores. Therefore, it is difficult to significantly improve the liquid absorption rate of the acrylic water absorbing resin simply by the above two methods.

Recently, it has been proposed to prepare an acrylic water absorbing resin having a high liquid absorption rate by changing the initiation mode or polymerization method of acrylic acid polymerization. Chinese public patent CN103360555A proposes to prepare a polymer gel by electron beam radiation crosslinking, and then extracting and freeze-drying to obtain a super absorbent resin. Chinese public patent CN103408689A proposes a method for synthesizing a transient suction type super absorbent resin, which is The water-absorbing resin was prepared by dispersing an aqueous solution of an acrylic monomer in an oil phase by inverse emulsion polymerization. These methods are difficult to industrialize because of the complexity of technology and high energy consumption, or because they are not environmentally friendly and do not meet the future development trend of the industry, so it is difficult to effectively improve the liquid absorption rate of acrylic water-absorbing resin to meet market demand.

Summary of the invention

One of the objects of the present invention is to provide an acrylic water absorbing resin having a high liquid absorption rate, which is a mixture of a conventional surfactant and an animal or vegetable protein surfactant as a high temperature resistant foaming agent. The foaming ability is strong, and the bubble is stable at high temperature, thereby overcoming the drawback that the bubble generated by the conventional porogenic technology is difficult to be stably existed in the high temperature environment of the thermally induced polymerization, so that the specific surface area of the acrylic water absorbing resin can be effectively improved. Since the surface of the water absorbing resin particles not only contains a large amount of hydrophilic groups, but also contains a large number of minute pores therein, the liquid absorption rate thereof is remarkably superior to the water absorbing resin products currently on the market, and is suitable for use in sanitary products to satisfy the market. demand.

To achieve the above object, the technical solution provided by the present invention is as follows:

A high liquid absorption rate acrylic water absorbing resin, wherein the raw material for preparing the same comprises: acrylic acid, alkali and water in a mass ratio of (25-45):(7-22):(33-68), further comprising: based on Acrylic mass meter,

Crosslinking agent: 0.001 to 1% by weight, preferably 0.005 to 0.8% by weight, more preferably 0.01 to 0.5% by weight;

High temperature resistant foaming agent: 0.01-2 wt%, preferably 0.05-1.8 wt%, more preferably 0.1-1.6 wt%;

Comonomer: 0-10% by weight, preferably 0.01-9% by weight, more preferably 0.1-8% by weight;

Reducing agent: 30-500 ppm, preferably 40-400 ppm, more preferably 50-300 ppm;

Initiator: 0.001 to 1 wt%, preferably 0.005 to 0.8 wt%, more preferably 0.01 to 0.5 wt%;

In one embodiment of the invention, the high liquid absorption rate acrylic water absorbing resin has a liquid absorption rate of from 15 to 40 s, preferably from 18 to 35 s, more preferably from 20 to 32 s.

In one embodiment of the invention, the base is sodium hydroxide.

In one embodiment of the invention, the crosslinking agent is ethylene glycol, propylene glycol, glycerin, polyethylene glycol, ethylene glycol diglycidyl ether, ethoxylated glycerin triacrylate, N, N-methylene One or two or more of a bisacrylamide, a polyethylene glycol diglycidyl ether, a pentaerythritol triacrylate, and a pentaerythritol triallyl ether, preferably pentaerythritol triacrylate.

In one embodiment of the present invention, the high temperature resistant foaming agent is a compounding foaming agent comprising a conventional surfactant and an animal and vegetable protein surfactant, and the mass ratio of the conventional surfactant to the animal and vegetable protein surfactant is 6 to 9:1 to 4.

In one embodiment of the invention, the conventional surfactant is sodium lauryl sulfate, sodium dodecyl sulfate, sodium fatty acid polyoxyethylene ether sulfate, sodium dodecylbenzenesulfonate, and a disc One or two or more of (Span) and Tween, preferably sodium lauryl sulfate; the animal and vegetable protein surfactant is sodium rosinate, tea saponin, saponin, hydrolysis One or two or more of animal horns and hydrolyzed blood gel, preferably saponin.

In one embodiment of the invention, the comonomer is one or more of a cationic vinyl monomer having a charged group and an anionic vinyl monomer, preferably sodium allyl sulfonate, methacryl Sodium sulfonate, 2-acrylamide-2-methylpropanesulfonic acid, acryloyloxyethyltrimethylammonium chloride, methacryloyloxyethyltrimethylammonium chloride and dimethyldiallyl One or two or more kinds of ammonium chloride are more preferably sodium allylsulfonate.

In one embodiment of the present invention, the reducing agent is one or two or more of sodium sulfite, sodium hydrogen sulfite, sodium hypophosphite and ascorbic acid, preferably sodium sulfite; the initiator is ammonium persulfate, One or two or more kinds of sodium sulfate, potassium persulfate and hydrogen peroxide, preferably ammonium persulfate.

In one embodiment of the present invention, in one embodiment of the present invention, the raw material for preparing the acrylic water absorbing resin further comprises a surface crosslinking agent; and optionally, a water soluble polymer.

Wherein the surface crosslinking agent is composed of one or two or more of water, a polyol, a glycidyl ether, a ethylene carbonate, a propylene carbonate, and a polyvalent metal compound; wherein the polyol includes Not limited to ethylene glycol, propylene glycol or glycerol, the polyvalent metal compound includes, but is not limited to, aluminum chloride, magnesium chloride, aluminum sulfate or calcium chloride; the water-soluble polymer is polyethylene glycol, polyvinyl alcohol One or two or more of polyacrylamide and polyvinylpyrrolidone, preferably polyvinyl alcohol.

In one embodiment of the invention, the water is preferably deionized water. Among them, a part of water is used as a solvent for acrylic acid, and another part of water is used as a solvent for sodium hydroxide.

Another object of the present invention is to provide a process for producing the above-mentioned high liquid absorption rate acrylic water absorbing resin.

The method for preparing the above acrylic water absorbing resin comprises the following steps:

a) dissolving acrylic acid in water to form an aqueous solution of acrylic acid, and neutralizing the aqueous solution of acrylic acid with an alkali solution to obtain To an incomplete neutralization solution containing acrylic acid;

b) adding a crosslinking agent, a high temperature resistant foaming agent and a reducing agent to the neutralized liquid obtained in the step a), optionally adding a comonomer, mixing uniformly, adding an initiator, and performing aqueous solution polymerization to obtain a hydrogel;

c) chopping the hydrogel obtained in step b), drying, crushing, and sieving to obtain a primary acrylic water absorbing resin;

d) Surface crosslinking of the primary acrylic water absorbing resin obtained in the step c) using a surface crosslinking agent, and then optionally spraying a water-soluble polymer aqueous solution on the surface of the particles to obtain an acrylic water absorbing resin.

In one embodiment, the lye used in the step a) of the preparation method of the present invention is an aqueous sodium hydroxide solution having a lye concentration of 30-50% by weight; and the quality of the acrylic acid, sodium hydroxide and water in the step a) The ratio is (25-45):(7-22):(33-68), and the degree of neutralization of the acrylic acid in the step a) is 50-90%.

The inventors of the present invention have found that the concentration of the aqueous acrylic acid solution in the neutralizing solution is too low, which leads to a slow polymerization reaction of the step b), and the obtained hydrogel has a high water content, which tends to prolong the drying time and increase the energy consumption; If the concentration is too high, the sodium acrylate will be precipitated during the neutralization of step a), and the polymerization reaction is severe, the heat is difficult to be emitted, and there is a risk of explosion.

In one embodiment, the comonomer may or may not be added in step b) of the preparation method of the present invention, the comonomer being one of a cationic vinyl monomer having a charged group and an anionic vinyl monomer. Species or two or more, preferably sodium allyl sulfonate, sodium methacrylate sulfonate, 2-acrylamide-2-methylpropane sulfonic acid, acryloyloxyethyltrimethylammonium chloride, A One or two or more of acryloyloxyethyltrimethylammonium chloride and dimethyldiallylammonium chloride are more preferably sodium allylsulfonate. When such a comonomer is polymerized into an acrylic water-absorbent resin network, it can produce a polymer electrostatic effect and promote the gel expansion and water absorption process.

Wherein the comonomer is added in an amount of from 0 to 10% by mass based on the mass of the acrylic monomer; preferably from 0.01 to 9% by weight, more preferably from 0.1 to 8% by weight.

In one embodiment, the crosslinking agent described in step b) of the preparation method of the present invention is ethylene glycol, propylene glycol, glycerin, polyethylene glycol, ethylene glycol diglycidyl ether, ethoxylated glycerol One or two or more of acrylate, N,N-methylenebisacrylamide, polyethylene glycol diglycidyl ether, pentaerythritol triacrylate, and pentaerythritol triallyl ether, preferably pentaerythritol triacrylate . The crosslinking agent is added in an amount of 0.001 to 1% by mass based on the mass of the acrylic monomer; preferably 0.005 to 0.8% by weight, more preferably 0.01 to 0.5% by weight.

In one embodiment, the initiator described in step b) of the preparation process of the invention is one or two or more of ammonium persulfate, sodium persulfate, potassium persulfate and hydrogen peroxide, preferably ammonium persulfate. . The initiator is added in an amount of 0.001 to 1% by mass based on the mass of the acrylic monomer; preferably 0.005 to 0.8% by weight, more preferably 0.01 to 0.5% by weight.

In one embodiment, the high temperature resistant foaming agent described in step b) of the preparation method of the present invention is a compounding foaming agent comprising a conventional surfactant and an animal and vegetable protein surfactant, and the mass ratio of the two is 6 to 9:1 to 4. The high temperature resistant blowing agent is added in an amount of from 0.01 to 2% by mass based on the mass of the acrylic acid; preferably from 0.05 to 1.8% by weight, more preferably from 0.1 to 1.6% by weight.

The conventional surfactant includes, but is not limited to, sodium lauryl sulfate, sodium dodecyl sulfate, sodium fatty acid polyoxyethylene ether sulfate, sodium dodecylbenzenesulfonate, Span, and Tween. Or two or more, preferably sodium lauryl sulfate.

The animal and vegetable protein surfactants include, but are not limited to, one or two or more of sodium rosinate, tea saponin, saponin, hydrolyzed animal horn and hydrolyzed blood gel, preferably saponin.

The high temperature resistant foaming agent used in the invention not only comprises a conventional surfactant, but also introduces an animal or vegetable protein surfactant. Under the action of stirring, not only the foaming ability is strong, but also the bubble can be stably existed for a long time under high temperature. Therefore, a large number of minute pores can still be produced in the gel under the high temperature environment of polymerization, and the specific surface area of the acrylic water absorbing resin particles is greatly improved.

In one embodiment, the reducing agent described in step b) of the preparation process of the invention is one or two or more of sodium sulfite, sodium hydrogen sulfite, sodium hypophosphite and ascorbic acid, preferably sodium sulfite. The reducing agent is added in an amount of 30 to 500 ppm with respect to the mass of the acrylic acid; preferably 40 to 400 ppm, more preferably 50 to 300 ppm.

By adjusting the amount of the reducing agent, the gel foaming time for controlling the reaction liquid can be from 5 to 100 s, preferably from 6 to 50 s, more preferably from 8 to 30 s.

In the preparation method of the invention, the amount of the reducing agent is extremely small, much smaller than the amount of the reducing agent required in the conventional redox system, which only promotes the generation of free radicals by a small amount of initiator, shortens the induction period of the heat-initiated polymerization, and thus is different. The traditional redox initiation system is also different from the pure thermal initiation system.

In one embodiment, the polymerization temperature of step b) of the preparation process of the invention is from 40 to 90 ° C and the polymerization time is from 3 to 30 min.

In one embodiment, the hydrogel described in the step c) of the preparation method of the present invention has a particle size of 4-14 mm after being chopped; a drying temperature of 100-200 ° C; and a drying time of 40-200 min. It is preferably 80-180 min.

In one embodiment, the primary acrylic water absorbing resin obtained in step c) of the preparation method of the present invention has a particle size ranging from 100 to 800 μm.

In one embodiment, the surface crosslinking agent that is surface crosslinked with the primary acrylic water absorbing resin in step d) of the preparation method of the present invention is water, polyol, glycidyl ether, ethylene carbonate, propylene carbonate, and multivalent. One or two or more of the metal compounds. The surface crosslinking agent is used in an amount of from 2 to 8% by mass based on the mass of the primary acrylic water absorbing resin of the step c). The reaction temperature of the surface crosslinking is 100-200 ° C, and the reaction time is 10-100 min.

Wherein, the polyol includes, but is not limited to, ethylene glycol, propylene glycol or glycerol, and the polyvalent metal compound includes, but is not limited to, aluminum chloride, magnesium chloride, aluminum sulfate or calcium chloride.

In one embodiment, in step d) of the preparation method of the present invention, a water-soluble polymer may be added or not, and the water-soluble polymer is polyethylene glycol, polyvinyl alcohol, polyacrylamide and polyethylene. One or two or more of pyrrolidone, preferably polyvinyl alcohol. Such water-soluble polymers all contain a large amount of hydrophilic polar groups, and after being applied to the surface of the acrylic water absorbing resin for hydrophilic strengthening, the wetting process of the acrylic water absorbing resin particles before water absorption can be greatly accelerated. The water-soluble polymer is added in an amount of from 0 to 10% by mass based on the mass of the primary acrylic water-absorbent resin powder of the step c).

In one embodiment, the acrylic water absorbing resin obtained in the step d) of the production method of the present invention has a particle diameter of from 100 to 800 μm, preferably from 300 to 500 μm. Among them, the acrylic acid water absorbing resin has a liquid absorption rate of 15 to 40 s, preferably 18 to 35 s, more preferably 20 to 32 s.

Still another object of the present invention is to provide an acrylic water absorbing resin for use as a liquid absorbing material in sanitary diapers, baby diapers and sanitary napkins, and as a water absorption and storage in desert treatment, oil field water shutoff, agriculture and forestry water conservation, and the like. The use of water materials.

According to the above technical solution, the present invention has the following advantages compared with the prior art:

(1) Introducing a new type of high temperature resistant foaming agent into the preparation process of acrylic water absorbing resin. This foaming agent not only has strong foaming ability, but also stabilizes bubbles at high temperature, thereby overcoming the problems caused by conventional porogen technology. The bubble is difficult to stabilize in the high temperature environment where the polymerization is initiated by heat, so it can effectively improve propylene. The specific surface area of the acid water absorbing resin.

(2) On the basis of thermal initiation, using a very small amount of reducing agent (only 30-500 ppm relative to the mass of acrylic acid), adjusting the gel foaming time of the reaction solution is beneficial to control the progress of the polymerization reaction and the gel. Stomatal content.

(3) Optionally, a charged cationic or anionic vinyl comonomer is added during the polymerization process to enhance the electrostatic effect of the acrylic water absorbing resin and the osmotic pressure difference inside and outside the gel network during water absorption, thereby promoting the gel water swell expansion process.

(4) After the surface cross-linking, the water-soluble polymer is optionally applied to the surface of the acrylic water absorbing resin to carry out hydrophilic strengthening, which contributes to promoting the wetting process of the particles before water absorption.

Due to the above technical advantages, the acrylic water absorbing resin accelerates the wetting process before water absorption, and the water absorbing process during water absorption is also accelerated. Therefore, the acrylic water absorbing resin prepared by the method has a high liquid absorption rate and can well satisfy the hygiene product market. Strict requirements for pipetting rate.

detailed description

In order to better understand the present invention, the contents of the present invention will be further clarified below with reference to the embodiments, but the content of the present invention is not limited to the following embodiments.

Example 1

a) To the reactor with a high-speed stirring device, 1250 g of acrylic acid and 3020 g of deionized water were added, and then 730 g of a 48% aqueous sodium hydroxide solution was gradually added to the reaction vessel to control the temperature of the neutralizing solution to 60 °C.

b) To the neutralized liquid obtained in the step a), 3.125 g of pentaerythritol triacrylate, 0.125 g of a foaming agent and 0.0375 g of sodium sulfite are added, and the foaming agent is composed of sodium dodecyl sulfate and sodium rosinate in a mass ratio of 9 Prepared by :1, stirred and mixed uniformly, the reaction liquid was quickly added to the polymerization tank, and 25 g of the prepared 10 wt% aqueous ammonium persulfate solution was added at the same time, and polymerization was carried out for 20 minutes to obtain a hydrogel.

c) The hydrogel obtained in step b) is crushed by a screw extruder to obtain gel particles having a particle size of 8-14 mm, and then dried in an oven at 180 ° C for 120 min, and then crushed by a pulverizer and classified by a sifter. Thereafter, a primary acrylic water absorbing resin powder is obtained.

d) using water, glycerol, ethylene glycol diglycidyl ether, aluminum chloride to prepare a surface crosslinking agent in a ratio of 300:140:80:110, the amount of surface crosslinking agent and the primary acrylic acid obtained in step c) The ratio of the resin powder was 5:100 (mass ratio, the same below). In the high-speed rotary mixer, according to the above ratio requirements The surface crosslinking agent is evenly sprayed onto the surface of the primary acrylic water absorbing resin powder, and after stirring for 5 minutes, the acrylic water absorbing resin powder is placed in an oven at 180 ° C, heated for 60 minutes, and taken out, and after grading by a sieving machine, an acrylic water absorbing resin product is obtained. The particle size is 400-700 μm.

Example 2

a) 2250 g of acrylic acid and 460 g of deionized water were placed in a reaction vessel equipped with a high-speed stirring apparatus, and then 2290 g of a 48% aqueous sodium hydroxide solution was gradually added to the reaction vessel to control the temperature of the neutralizing solution to 60 °C.

b) To the neutralized solution obtained in step a), 1.125 g of N,N-methylenebisacrylamide, 45 g of a blowing agent and 1.125 g of sodium sulfite are added, and the blowing agent is selected from sodium lauryl sulfate and saponin. Prepared at 6:4, stirred and mixed uniformly, the reaction solution was quickly added to the polymerization tank, and 67.5 g of the prepared 10% ammonium persulfate aqueous solution was added at the same time, and polymerization was carried out for 5 minutes to obtain a hydrogel.

c) The hydrogel obtained in step b) is crushed by a screw extruder to obtain gel particles having a particle size of 6-12 mm, and then dried in an oven at 180 ° C for 120 min, and then crushed by a pulverizer and classified by a sifter. Thereafter, a primary acrylic water absorbing resin powder is obtained.

d) preparing a surface crosslinking agent, a surface crosslinking agent and a primary acrylic water absorbing resin obtained in the step c) with water, glycerol, ethylene glycol diglycidyl ether, aluminum chloride in a ratio of 300:140:80:110 The powder ratio was 7:100. In the high-speed rotary mixer, the surface crosslinking agent was uniformly sprayed onto the surface of the primary acrylic water-absorbent resin powder according to the above ratio requirement, and after stirring for 5 minutes, the acrylic water-absorbent resin powder was placed in an oven at 180 ° C, and then taken out after heating for 60 minutes. After the sieving machine is classified, an acrylic water absorbing resin product is obtained, and the particle size is 300-500 μm.

Example 3

a) 1500 g of acrylic acid and 2200 g of deionized water were placed in a reaction vessel equipped with a high-speed stirring apparatus, and then 1300 g of a 48% aqueous sodium hydroxide solution was gradually added to the reaction vessel to control the temperature of the neutralizing solution to 60 °C.

b) adding 4.5 g of polyethylene glycol diglycidyl ether, 6 g of a blowing agent and 0.12 g of sodium hydrogen sulfite to the neutralized liquid obtained in the step a), the foaming agent is sodium dodecylbenzenesulfonate and tea The saponin was prepared in a ratio of 7:3. After stirring and mixing uniformly, the reaction solution was quickly added to the polymerization tank, and 48 g of the prepared 10% aqueous ammonium persulfate solution was simultaneously added, and a polymerization reaction was carried out for 8 minutes to obtain a hydrogel.

c) The hydrogel obtained in step b) is crushed by a screw extruder to obtain a coagulation having a particle size of 4-10 mm. The gum particles were then dried in an oven at 180 ° C for 120 min, and then crushed by a pulverizer and classified by a sieving machine to obtain a primary acrylic water absorbing resin powder.

d) preparing a surface crosslinking agent, a surface crosslinking agent and a primary acrylic water absorbing resin obtained in the step c) with water, glycerol, ethylene glycol diglycidyl ether, aluminum chloride in a ratio of 300:140:80:110 The powder ratio was 4:100. In the high-speed rotary mixer, the surface crosslinking agent was uniformly sprayed onto the surface of the primary acrylic water absorbing resin powder according to the above ratio requirement, and after stirring for 5 minutes, the acrylic water absorbing resin powder was placed in an oven at 180 ° C, and then taken out after heating for 60 minutes. The polyethylene glycol aqueous solution having a concentration of 10% was sprayed onto the surface of the resin powder by a sprayer to carry out hydrophilic strengthening. The ratio of the polyethylene glycol aqueous solution to the resin powder was 4:100, and finally, the sieve was classified to obtain acrylic acid. A water absorbing resin product having a particle size of 100-600 μm.

Example 4

a) 1700 g of acrylic acid and 1920 g of deionized water were placed in a reaction vessel equipped with a high-speed stirring apparatus, and then 1380 g of a 48% aqueous sodium hydroxide solution was gradually added to the reaction vessel to control the temperature of the neutralizing solution to 60 °C.

b) adding 25.5 g of sodium methacrylate comonomer, 3.4 g of ethoxylated glycerol triacrylate, 3.4 g of foaming agent and 0.085 g of sodium hypophosphite to the neutralized liquid obtained in the step a) The foaming agent is prepared by the fatty alcohol polyoxyethylene ether sulfate and the hydrolyzed animal hoof foot by 6:4. After stirring and mixing uniformly, the reaction liquid is quickly added to the polymerization tank, and 51 g of the prepared 10% is added at the same time. An aqueous solution of ammonium sulfate was obtained after polymerization for 18 minutes to obtain a hydrogel.

c) The hydrogel obtained in step b) is crushed by a screw extruder to obtain gel particles having a particle size of 6-12 mm, and then dried in an oven at 180 ° C for 120 min, and then crushed by a pulverizer and classified by a sifter. Thereafter, a primary acrylic water absorbing resin powder is obtained.

d) preparing a surface crosslinking agent, a surface crosslinking agent and a primary acrylic water absorbing resin obtained in the step c) with water, glycerol, ethylene glycol diglycidyl ether, aluminum chloride in a ratio of 300:140:80:110 The powder ratio was 6:100. In the high-speed rotary mixer, the surface crosslinking agent was uniformly sprayed onto the surface of the primary acrylic water-absorbent resin powder according to the above ratio requirement, and after stirring for 5 minutes, the acrylic water-absorbent resin powder was placed in an oven at 180 ° C, and then taken out after heating for 60 minutes. After the sieving machine is classified, an acrylic water absorbing resin product is obtained, and the particle size is 300-800 μm.

Example 5

a) 1900 g of acrylic acid and 1670 g of deionized water were placed in a reaction vessel equipped with a high-speed stirring apparatus, and then 1430 g of a 48% aqueous sodium hydroxide solution was gradually added to the reaction vessel to control the temperature of the neutralizing solution to 60 °C.

b) adding 19 g of 2-acrylamide-2-methylpropanesulfonic acid comonomer, 2.85 g of pentaerythritol triallyl ether, 5.7 g of foaming agent and 0.19 g of ascorbic acid to the neutralized solution obtained in the step a) The foaming agent is prepared by sodium dodecyl sulfate and hydrolyzed blood gel according to 8:2. After stirring and mixing uniformly, the reaction liquid is quickly added to the polymerization tank, and 47.5 g of prepared 10% ammonium persulfate is simultaneously added. The aqueous solution was hydrolyzed after 12 minutes of polymerization.

c) The hydrogel obtained in step b) is crushed by a screw extruder to obtain gel particles having a particle size of 5-10 mm, and then dried in an oven at 180 ° C for 120 min, and then crushed by a pulverizer and classified by a sifter. Thereafter, a primary acrylic water absorbing resin powder is obtained.

d) preparing a surface crosslinking agent, a surface crosslinking agent and a primary acrylic water absorbing resin obtained in the step c) with water, glycerol, ethylene glycol diglycidyl ether, aluminum chloride in a ratio of 300:140:80:110 The powder ratio was 7:100. In the high-speed rotary mixer, the surface crosslinking agent was uniformly sprayed onto the surface of the primary acrylic water absorbing resin powder according to the above ratio requirement, and after stirring for 5 minutes, the acrylic water absorbing resin powder was placed in an oven at 180 ° C, and then taken out after heating for 60 minutes. The polyacrylamide aqueous solution having a concentration of 10% was sprayed onto the surface of the resin powder by a sprayer to carry out hydrophilic strengthening. The ratio of the polyacrylamide aqueous solution to the resin powder was 3:100, and finally, the acrylic acid was obtained by grading by a sieve. A resin product having a particle size of 200-600 μm.

Example 6

a) 2000 g of acrylic acid and 1300 g of deionized water were placed in a reactor equipped with a high-speed stirring apparatus, and then 1700 g of a 48% aqueous sodium hydroxide solution was gradually added to the reaction vessel to control the temperature of the neutralized liquid to 60 °C.

b) adding 24 g of sodium allyl sulfonate comonomer, 2.4 g of pentaerythritol triacrylate, 6 g of blowing agent and 0.18 g of sodium sulfite to the neutralized solution obtained in step a), the blowing agent is composed of sodium lauryl sulfate And hydrolyzed blood gelatin and saponin prepared in 7:1:2, stirred and mixed uniformly, the reaction liquid was quickly added to the polymerization tank, and simultaneously added 70g of prepared 10% ammonium persulfate aqueous solution, polymerization A hydrogel was obtained after 15 min.

c) The hydrogel obtained in step b) is crushed by a screw extruder to obtain gel particles having a particle size of 6-12 mm, and then dried in an oven at 180 ° C for 120 min, and then crushed by a pulverizer and classified by a sifter. Rear, A primary acrylic water absorbing resin powder is obtained.

d) preparing a surface crosslinking agent, a surface crosslinking agent and a primary acrylic water absorbing resin obtained in the step c) with water, glycerol, ethylene glycol diglycidyl ether, aluminum chloride in a ratio of 300:140:80:110 The powder ratio was 5:100. In the high-speed rotary mixer, the surface crosslinking agent was uniformly sprayed onto the surface of the primary acrylic water absorbing resin powder according to the above ratio requirement, and after stirring for 5 minutes, the acrylic water absorbing resin powder was placed in an oven at 180 ° C, and then taken out after heating for 60 minutes. The aqueous solution of polyvinyl alcohol having a concentration of 10% was sprayed onto the surface of the resin powder by a sprayer to carry out hydrophilic strengthening, and the ratio of the aqueous solution of the polyvinyl alcohol and the resin powder was 6:100, and finally, the acrylic resin was obtained by fractionation by a sieve. The product has a particle size of 200-500 μm.

Comparative example 1

a) 1750 g of acrylic acid and 1830 g of deionized water were placed in a reaction vessel equipped with a high-speed stirring apparatus, and then 1420 g of a 48% aqueous sodium hydroxide solution was gradually added to the reaction vessel to control the temperature of the neutralizing solution to 60 °C.

b) adding 2.1 g of pentaerythritol triacrylate to the neutralized liquid obtained in the step a), stirring and mixing uniformly, the reaction liquid is quickly added to the polymerization tank, and 52.5 g of the prepared 10% ammonium persulfate aqueous solution is simultaneously added. After the polymerization reaction for 10 min, a hydrogel was obtained.

c) The hydrogel obtained in step b) is crushed by a screw extruder to obtain gel particles having a particle size of 4-14 mm, and then dried in an oven at 180 ° C for 120 min, and then crushed by a pulverizer and classified by a sifter. Thereafter, a primary acrylic water absorbing resin powder is obtained.

d) preparing a surface crosslinking agent, a surface crosslinking agent and a primary acrylic water absorbing resin obtained in the step c) with water, glycerol, ethylene glycol diglycidyl ether, aluminum chloride in a ratio of 300:140:80:110 The powder ratio was 5:100. In the high-speed rotary mixer, the surface crosslinking agent was uniformly sprayed onto the surface of the primary acrylic water-absorbent resin powder according to the above ratio requirement, and after stirring for 5 minutes, the acrylic water-absorbent resin powder was placed in an oven at 180 ° C, and then taken out after heating for 60 minutes. After the sieving machine is classified, an acrylic water absorbing resin product is obtained, and the particle size is 300-500 μm.

Comparative example 2

a) 2000 g of acrylic acid and 1300 g of deionized water were placed in a reactor equipped with a high-speed stirring apparatus, and then 1700 g of a 48% aqueous sodium hydroxide solution was gradually added to the reaction vessel to control the temperature of the neutralized liquid to 60 °C.

b) adding 24 g of sodium allyl sulfonate comonomer and 2.4 g of pentaerythritol to the neutralized solution obtained in step a) After the triacrylate was stirred and mixed uniformly, the reaction liquid was quickly added to the polymerization tank, and 60 g of the prepared 10% ammonium persulfate aqueous solution was simultaneously added, and the polymerization was carried out for 10 minutes to obtain a hydrogel.

c) The hydrogel obtained in step b) is crushed by a screw extruder to obtain gel particles having a particle size of 4-14 mm, and then dried in an oven at 180 ° C for 120 min, and then crushed by a pulverizer and classified by a sifter. Thereafter, a primary acrylic water absorbing resin powder is obtained.

d) preparing a surface crosslinking agent, a surface crosslinking agent and a primary acrylic water absorbing resin obtained in the step c) with water, glycerol, ethylene glycol diglycidyl ether, aluminum chloride in a ratio of 300:140:80:110 The powder ratio was 5:100. In the high-speed rotary mixer, the surface crosslinking agent was uniformly sprayed onto the surface of the primary acrylic water-absorbent resin powder according to the above ratio requirement, and after stirring for 5 minutes, the acrylic water-absorbent resin powder was placed in an oven at 180 ° C, and then taken out after heating for 60 minutes. After the sieving machine is classified, an acrylic water absorbing resin product is obtained, and the particle size is 300-500 μm.

The acrylic acid water absorbing resin products obtained in the above examples and comparative examples were subjected to a liquid absorption rate test (see Table 1), and the test method was a vortex method, and the specific steps were as follows:

(1) Weigh 50g of normal saline and pour it into a beaker with a capacity of 100ml;

(2) placing the beaker on a constant temperature magnetic stirrer, controlling the temperature of the physiological saline to 25 ° C, placing a 25 mm diameter iron core PTFE stirrer, and starting to stir;

(3) After observing the vortex of the solution in the beaker and stabilizing, add 2g of acrylic water absorbing resin and start timing. When the vortex disappears, the time is the product's liquid absorption rate.

Table 1 Acrylic water absorption resin absorption rate table

	Suction rate (s)
		Example 1	32
Example 2	twenty three
		Example 3	twenty four
Example 4	26
		Example 5	twenty one
Example 6	20
		Comparative example 1	51
Comparative example 2	48

As seen from Table 1, the acrylic acid water absorbing resin of the present invention has a much higher liquid absorption rate than the acrylic water absorbing resin prepared in Comparative Example 1-2.

Claims (28)

1. A high liquid absorption rate acrylic water absorbing resin characterized in that the raw material for preparing the same comprises: acrylic acid, alkali and water in a mass ratio of (25-45):(7-22):(33-68), and includes : based on acrylic mass,

   Crosslinking agent: 0.001 to 1% by weight, preferably 0.005 to 0.8% by weight, more preferably 0.01 to 0.5% by weight;

   High temperature resistant foaming agent: 0.01-2 wt%, preferably 0.05-1.8 wt%, more preferably 0.1-1.6 wt%;

   Comonomer: 0-10% by weight, preferably 0.01-9% by weight, more preferably 0.1-8% by weight;

   Reducing agent: 30-500 ppm, preferably 40-400 ppm, more preferably 50-300 ppm;

   Initiator: 0.001 to 1 wt%, preferably 0.005 to 0.8 wt%, more preferably 0.01 to 0.5 wt%.
2. The acrylic water absorbing resin according to claim 1, wherein the acrylic water absorbing resin has a liquid absorption rate of from 15 to 40 s, preferably from 18 to 35 s, more preferably from 20 to 32 s.
3. The acrylic water absorbing resin according to claim 1 or 2, wherein the base is sodium hydroxide.
4. The acrylic water absorbing resin according to claim 1 or 2, wherein the crosslinking agent is ethylene glycol, propylene glycol, glycerin, polyethylene glycol, ethylene glycol diglycidyl ether, ethoxylated glycerin One or two or more of acrylate, N,N-methylenebisacrylamide, polyethylene glycol diglycidyl ether, pentaerythritol triacrylate, and pentaerythritol triallyl ether, preferably pentaerythritol triacrylate .
5. The acrylic water absorbing resin according to claim 1 or 2, wherein the high temperature resistant foaming agent is a compounding foaming agent comprising a conventional surfactant and an animal or vegetable protein surfactant; a conventional surfactant and a moving agent The mass ratio of the vegetable protein surfactant is from 6 to 9:1 to 4.
6. The acrylic water absorbing resin according to claim 5, wherein the conventional surfactant is sodium lauryl sulfate, sodium dodecyl sulfate, sodium polyoxyethylene ether sulfate, and dodecyl group. One or two or more of sodium benzenesulfonate, Span and Tween, preferably sodium lauryl sulfate; the animal and vegetable protein surfactants are sodium rosinate, tea saponin, saponin, One or two or more of hydrolyzed animal horns and hydrolyzed blood gel, preferably saponin.
7. The acrylic water absorbing resin according to claim 1 or 2, wherein the The original agent is one or two or more of sodium sulfite, sodium hydrogen sulfite, sodium hypophosphite and ascorbic acid, preferably sodium sulfite.
8. The acrylic water absorbing resin according to claim 1 or 2, wherein the initiator is one or two or more kinds of ammonium persulfate, sodium persulfate, potassium persulfate and hydrogen peroxide, preferably ammonium persulfate. .
9. The acrylic water absorbing resin according to claim 1 or 2, wherein the comonomer is one or more of a cationic vinyl monomer and an anionic vinyl monomer having a charged group, preferably an olefin. Sodium propyl sulfonate, sodium methacrylate sulfonate, 2-acrylamide-2-methylpropane sulfonic acid, acryloyloxyethyltrimethylammonium chloride, methacryloyloxyethyltrimethyl chloride One or two or more of ammonium and dimethyldiallylammonium chloride, more preferably sodium allylsulfonate.
10. The acrylic water absorbing resin according to claim 1 or 2, wherein the water is deionized water.
11. A method of preparing the acrylic water absorbing resin according to any one of claims 1 to 10, comprising the steps of:

    a) dissolving acrylic acid in water to form an aqueous solution of acrylic acid, and neutralizing the aqueous solution of acrylic acid with an alkali solution to obtain an incomplete neutralization liquid containing acrylic acid;

    b) adding a crosslinking agent, a high temperature resistant foaming agent and a reducing agent to the neutralized liquid obtained in the step a), optionally adding a comonomer, mixing uniformly, adding an initiator, and performing aqueous solution polymerization to obtain a hydrogel;

    c) chopping the hydrogel obtained in step b), drying, crushing, and sieving to obtain a primary acrylic water absorbing resin;

    d) Surface crosslinking of the primary acrylic water absorbing resin obtained in the step c) using a surface crosslinking agent, and then optionally spraying a water-soluble polymer aqueous solution on the surface of the particles to obtain an acrylic water absorbing resin.
12. The method according to claim 11, wherein the alkali liquid used in the step a) is an aqueous sodium hydroxide solution, and the concentration of the alkali liquid is 30 to 50% by weight.
13. The method according to claim 12, wherein the mass ratio of acrylic acid, sodium hydroxide and water in step a) is (25-45):(7-22):(33-68).
14. The method according to claim 11, wherein the high temperature resistant foaming agent in the step b) is a mixture comprising a conventional surfactant and an animal and vegetable protein surfactant, and the mass ratio of the two is 6 to 9:1 to 4; the amount of the high temperature resistant foaming agent added is relative to the mass of the acrylic acid 0.01-2%, preferably 0.05-1.8 wt%, more preferably 0.1-1.6 wt%.
15. The method according to claim 14, wherein said conventional surfactant is selected from the group consisting of sodium lauryl sulfate, sodium dodecyl sulfate, sodium fatty acid polyoxyethylene ether sulfate, and dodecylbenzene. One or two or more of sodium sulfonate, spar and Tween, preferably sodium lauryl sulfate; the animal and vegetable protein surfactant is selected from the group consisting of sodium rosinate, tea saponin, saponin, One or two or more of hydrolyzed animal horns and hydrolyzed blood gel, preferably saponin.
16. The method according to claim 11, wherein the comonomer in step b) is one or more of a cationic vinyl monomer and an anionic vinyl monomer having a charged group, preferably Sodium allyl sulfonate, sodium methacrylate sulfonate, 2-acrylamide-2-methylpropane sulfonic acid, acryloyloxyethyltrimethylammonium chloride, methacryloyloxyethyltrimethyl chloride One or two or more of ammonium hydride and dimethyl diallyl ammonium chloride, more preferably sodium allyl sulfonate; the comonomer is added in an amount of 0-10 relative to the mass of the acrylic acid. %, preferably 0.01 to 9 wt%, more preferably 0.1 to 8 wt%.
17. The method according to claim 11, wherein the crosslinking agent in the step b) is ethylene glycol, propylene glycol, glycerin, polyethylene glycol, ethylene glycol diglycidyl ether, ethoxylated glycerin. One or two or more of triacrylate, N,N-methylenebisacrylamide, polyethylene glycol diglycidyl ether, pentaerythritol triacrylate, and pentaerythritol triallyl ether, preferably pentaerythritol triacrylate The ester; the crosslinking agent is added in an amount of 0.001 to 1%, preferably 0.005 to 0.8% by weight, more preferably 0.01 to 0.5% by weight based on the mass of the acrylic monomer.
18. The method according to claim 11, wherein the initiator in the step b) is one or two or more kinds of ammonium persulfate, sodium persulfate, potassium persulfate and hydrogen peroxide, preferably persulfuric acid. Ammonium; the initiator is added in an amount of 0.001 to 1%, preferably 0.005 to 0.8% by weight, more preferably 0.01 to 0.5% by weight based on the mass of the acrylic monomer.
19. The method according to claim 11, wherein the reducing agent in the step b) is one or two or more of sodium sulfite, sodium hydrogen sulfite, sodium hypophosphite and ascorbic acid, preferably sodium sulfite; The amount of the agent added is 30 to 500 ppm with respect to the mass of the acrylic acid.
20. The method according to any one of claims 11 to 19, wherein the polymerization temperature of the step b) is 40 to 90 ° C and the polymerization time is 3 to 30 minutes.
21. The method according to claim 11, wherein the hydrogel in step c) is chopped to have a particle size of 4-14 mm; the drying temperature is 100-200 ° C, and the drying time is 40-200 min, preferably 80-180 min.
22. The method according to claim 21, wherein the primary acrylic water absorbing resin obtained in the step c) has a particle size ranging from 100 to 800 μm.
23. The method according to claim 11, wherein the surface crosslinking agent which is surface-crosslinked with the primary acrylic water absorbing resin in the step d) is water, polyol, glycidyl ether, ethylene carbonate, propylene carbonate and One or two or more of the valent metal compounds; the surface crosslinking agent is used in an amount of from 2 to 8% by mass based on the mass of the primary acrylic water absorbing resin of the step c).
24. The method according to claim 23, wherein the polyol comprises ethylene glycol, propylene glycol or glycerin; and the polyvalent metal compound comprises aluminum chloride, magnesium chloride, aluminum sulfate or calcium chloride.
25. The method according to claim 23 or 24, wherein the surface crosslinking has a reaction temperature of 100 to 200 ° C and a reaction time of 10 to 100 min.
26. The method according to claim 11, wherein the water-soluble polymer in the step d) is one or two or more of polyethylene glycol, polyvinyl alcohol, polyacrylamide and polyvinylpyrrolidone. Preferably, the polyvinyl alcohol is added; the water-soluble polymer is added in an amount of from 0 to 10% by mass based on the mass of the primary acrylic water-absorbent resin of the step c).
27. The method according to claim 11, wherein the acrylic water absorbing resin obtained in the step d) has a liquid absorption rate of from 15 to 40 s, preferably from 18 to 35 s, more preferably from 20 to 32 s.
28. The acrylic water absorbing resin according to any one of claims 1 to 10 or the acrylic water absorbing resin prepared by the method according to any one of claims 11 to 27 for use as a liquid absorbing material for sanitary diapers, baby diapers and sanitary napkins, and It is used as a water-absorbing and water-storing material in desert control, oil field water shutoff, and agriculture, forestry, and water conservation industries.