TWI473844B - Process for the production of a superabsorbent polymer - Google Patents

Description

Method for producing super absorbent resin

The invention relates to a water absorbing material with good absorption to an aqueous solution, which is called a super absorbent resin. The super absorbent resin has strong water retention capacity, can absorb water of 100 times or even thousands of times its own weight, and has a swelling after water absorption. The state of flow; even if pressure is applied, it will not leak, and the absorbed water can be slowly released in the atmosphere. At present, this superabsorbent resin is widely used in water retaining agents for agriculture or horticulture, anti-dew beading agents in building materials, materials for removing moisture in petroleum or outer layer waterproofing coatings in cable and sanitary Supplies such as diapers, feminine hygiene products, disposable wipes, etc.

Since the above superabsorbent resin is in direct contact with the human body, its safety becomes very important. In general, the physical properties of the superabsorbent resin include absorption rate, absorption, absorption under pressure, low monomer residual, and gel strength after absorption. The excellent superabsorbent resin not only has to satisfy the above physical properties, has good safety, and more importantly, must have low pollution and energy saving.

It is known that a component material for producing a super absorbent resin is a hydrolyzed starch acrylonitrile graft polymer (Japanese Patent Laid-Open Publication No. Sho 49 (1974)-43,395), and neutralized starch-acrylic acid. Branch polymer (Japanese Patent Publication No. Sho 51 (1976)-125,468), saponified ethylene acetate-propylene ester copolymer (Japanese Patent Laid-Open Publication No. Sho 52 (1977)-14, 689), hydrolyzed acrylonitrile copolymer or acrylamide copolymer (Japanese Patent Publication No. Sho 53(1978)-15,959), and partially neutralized polyacrylic acid (Japanese Patent Laid-Open Publication No. Sho 55 (1980)-84,304) and the like. Among them, the raw material for the production of the starch-acrylonitrile graft polymer is easily decomposed due to the inclusion of starch, and cannot be stored for a long period of time, and the manufacturing method thereof is also very complicated. Therefore, the general preparation method of the high water-absorbent resin is often used. The acrylic acid and/or acrylate containing an acid group-containing monomer is neutralized by NaOH and cross-linked and polymerized to produce a super absorbent resin, which is mainly because the raw material of the acrylate copolymer-acrylic acid can be rapidly mass-produced by industrialization, and The highly water-absorptive resin obtained has a high water absorption capacity, and has a low cost of production, is most economical, and is less likely to cause decomposition of rot, and thus is the most general-purpose superabsorbent resin in the technical field.

[Problems to be solved by the invention]

However, the above-mentioned superabsorbent resin still has a serious problem. When the superabsorbent resin absorbs the fluid, the fluid cannot be smoothly transferred to other superabsorbent resins which have not absorbed the fluid due to the excessively fast absorption speed, and cannot be completely presented. Superior absorption capacity of super absorbent resin.

In order to solve this problem, a solution disclosed in the international patent WO 91/04361 is to mix ethyl cellulose with an organic solvent and add it to a superabsorbent resin under heating to carry out a polymerization reaction to produce a The fluid transfer is smoother and has a high-absorbency resin with slow absorption. However, the manufacturing process and results are carefully investigated. It is found that this additive solution is sprayed with organic solvent and heat-treated, which may cause a fire crisis for large-scale industrial production. The added cellulose may have a tendency to be easily decomposed for long-term storage of the superabsorbent resin; in addition, the Chinese patent CN 101433733A discloses that a large amount of a metal salt aqueous solution is added to the superabsorbent resin and then dried to obtain a A highly absorbent resin that absorbs sluggishness, but it is required to be subjected to a drying process and a grinding screen after being sprayed with an aqueous solution to a highly water-absorptive resin to obtain an intended finished product. This method is disadvantageous for energy consumption and economic efficiency of superabsorbent resin production.

[Technical means to solve the problem]

In order to solve the above problem, it has been found that a highly water-absorptive resin having a water-repellent property can be obtained by applying a water-soluble thermoplastic resin to a superabsorbent resin. Promotes the expected efficacy of superabsorbent resins to slow absorption.

An object of the present invention is to provide a superabsorbent resin having excellent absorption ability and a method for producing the same.

Still another object of the present invention is to provide a production method in which a water-soluble thermoplastic resin is applied to a surface layer of a super absorbent resin to continue the free absorption speed.

According to the present invention, the water-soluble thermoplastic resin coating treatment can be directly carried out in a powder-feeding manner in the surface crosslinking reaction process section of the superabsorbent resin, without additional equipment or energy. The coating material used is selected from polyethylene glycol or polyvinyl alcohol; wherein the polyethylene glycol has a molecular weight of 1000 to 10000, the optimal molecular weight is 1000 to 8000, and the polyethylene glycol has a molecular weight of less than 1000. It is a fatty semi-solid or liquid. When it is added as a solid phase, its dispersibility is poor. If the molecular weight is 10,000 or more, its water solubility is low, which makes the superabsorbent resin after coating exhibit poor performance per unit time. It is not conducive to enhancing economic value, so the optimal molecular weight of polyethylene glycol is 1000~8000. The polyvinyl alcohol may be selected from a molecular weight of 300 to 2000, and the optimum molecular weight is 300 to 1000. The polyvinyl alcohol having a molecular weight of less than 300 is also semi-solid or liquid. If added by a solid phase, the dispersibility is poor; the molecular weight is above 2000. The polyvinyl alcohol has a low water solubility, so that the superabsorbent resin after coating has poor absorption performance per unit time, which is not conducive to economic value. The timing of the free water absorption of the present invention (free water absorption in a short time, that is, about one minute or longer than one minute) means absorption with a reduced or slower retardation, and absorbs water with a general superabsorbent resin until Can not absorb the difference, the latter usually 3 to 5 minutes.

The degree of alcoholysis of the polyvinyl alcohol used in the present invention is 60 mol% to 90% mol%, and the degree of alcoholysis is preferably 80 mol% to 89 mol%, because the degree of alcoholysis is representative of the water solubility of the corresponding polyvinyl alcohol. If the degree of alcoholysis is more than 90 mol% or less than 60 mol%, the solubility in water is low and slow in unit time, resulting in poor absorption of the superabsorbent resin after coating per unit time. The economic value thereof, the degree of alcoholysis refers to the degree of hydrolysis of the polyvinyl acetate obtained by the polymerization of the starting material ethylene acetate in the process of producing polyvinyl alcohol, and then obtained by hydrolysis. It is called the degree of alcoholysis.

The hydrophilic resin representing an acrylic polymer has a hydrophilic functional group such as an acid group, a mercaptoamine group, an amino group, a sulfonic acid group or the like on the hydrophilic resin polymer chain, and the hydrophilic resin of the present invention comprises: Polyacrylic acid or a salt thereof containing an alkali metal cation salt or an ammonium salt such as lithium, sodium or potassium, and a polymer of the foregoing, and neutralizing the acrylic acid after the neutralization (ie, the acrylic portion) And acrylates are in the range of 30 to 70 mol%, and may be copolymerized with water-soluble or water-insoluble monomers, which may be methacrylic acid, maleic acid, or rich. Horse acid, crotonic acid, itaconic acid, vinyl sulfonic acid, 2-(meth) acrylamide amine-2-methylpropane sulfonic acid, (meth) propylene decyloxy alkane sulfonic acid, and the base to which it belongs A metal cation salt or an ammonium salt or the like, and a monomer such as N-vinylacetamide, (meth) acrylamide or N,N-dimethyl acrylamide.

When the present invention uses a monomer other than the above acrylic acid, it is used in an amount of 50% or less, preferably 30% or less, based on the total amount of the acrylic acid, and the optimum use amount is not more than 10% of the acrylic monomer.

The present invention is used for producing an unsaturated monomer of a super absorbent resin, mainly one or a mixture of two or more of acrylic acid or a salt thereof, but based on functional and physical properties, the neutralization ratio of acrylic acid is relatively large. Preferably, it is 50 to 95 mol%, preferably 60 to 80 mol%; and the salt of the neutralized acrylate is an alkali metal salt or an ammonium salt, preferably a lithium or sodium salt.

It is generally known that the production of water-absorbent resins is carried out by adding a radical polymerization crosslinking agent to a radical reaction in an unreacted monomer solution before radical polymerization, and the radical polymerization crosslinking agent can be used with two or two. Compounds with more than one unsaturated double bond, such as: N,N'-bis(2-propenyl)amine, N,N'-methacrylic bis decylamine, N,N'-methine bismethacryl Indoleamine, propylene acrylate, ethylene glycol diacrylate, polyethylene glycol diacrylate, ethylene glycol dimethacrylate, polyethylene glycol dimethacrylate, glycerol triacrylate, trimethyl glycerol Acrylate, glycerin plus ethylene oxide triacrylate or trimethacrylate, trimethylolpropane plus ethylene oxide triacrylate or trimethacrylate, trimethylolpropane trimethacrylate, trimethylol Propane triacrylate, N,N,N-tris(2-propenyl)amine, ethylene glycol diacrylate, polyoxyethylene glyceryl triacrylate, diethyl polyoxyethylene glyceryl triacrylate, dipropylene triglyceride Alcohol ester or the like; may also be selected from two or more epoxy groups Compounds such as: sorbitol polyglycidyl ether, polyglycerol polyglycidyl ether, ethylene glycol diglycidyl ether, diethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, diglycerol poly Glycidyl ether and the like.

The radical polymerization crosslinking agent can impart a proper degree of crosslinking and a suitable processability to the superabsorbent resin after the radical reaction.

The radical polymerization crosslinking agent may be used singly or in combination of two or more. A suitable amount of the additive is between 0.001% by weight and 5% by weight based on the total solids of the reactants, more suitably between 0.01% and 3% by weight. The added dose is 0.001% by weight or less, and the hydrated body after polymerization is too soft and viscous to be unfavorably mechanically processed. When the amount of the additive is 5% by weight or more, the water absorbing property is too low, and the performance of the superabsorbent resin is lowered.

The polymerization begins with the decomposition of the radical polymerization initiator to generate free radicals. The free radical initiator may be selected from a thermal decomposition type initiator, and the suitable thermal decomposition initiator is a peroxide such as hydrogen peroxide, di-tert-butyl peroxide, guanidinium peroxide or persulfate. Salt (ammonium salt, alkali metal salt), etc.; and azo compound such as: 2.2'-azobis(2-amidinopropane) dihydrochloride, 2.2'-azobis (N, N-dip) Methyl isobutyl hydrazine) dihydrochloride; a reducing agent may also be used as a redox-type initiator, such as an acidic sulfite, thiosulfate, ascorbic acid or ferrous salt; or a redox-type initiator The agent and the thermal decomposition type initiator are used in combination. First, the reaction is carried out by a redox initiator to generate a radical, and the radical is transferred to the monomer to initiate the polymerization reaction. As the polymerization proceeds, a large amount of heat is released to raise the temperature, and the temperature is reached. When the decomposition temperature of the thermal decomposition type initiator starts, the decomposition of the second stage thermal decomposition type initiator is again caused, so that the entire polymerization reaction is more complete.

A suitable amount of the radical polymerization initiator is usually 0.001% by weight to 10% by weight based on the weight of the neutralized acrylate, more preferably between 0.1% and 5% by weight, and 0.001 by weight. When the weight is less than wt%, the reaction is too slow to be economically advantageous. When the weight percentage is 10% by weight or more, the reaction is too fast and the reaction heat is not easily controlled.

The polymerization reaction can be carried out in a conventional batch reaction vessel or on a conveyor belt reactor, and the superabsorbent resin obtained by the reaction is first cut into small gels having a diameter of 2.00 mm or less by a mincer and then subjected to screening. The diameter of the gel with a fixed particle size is preferably 2.00 mm or less, preferably between 0.05 mm and 1.50 mm, and the gel having a particle diameter of more than 2.00 mm is returned to the mincer for re-shearing.

The gel having a particle diameter of 0.05 mm or less is subjected to drying and pulverization treatment, and it is easy to increase the amount of fine powder produced. When the gel having a particle diameter of 2.00 mm or more is dried, it is easy to cause residual monomer in the finished product due to poor heat conduction effect. High, the shortcomings of poor physical performance.

The more concentrated the particle size distribution of the acrylate gel, the better the physical properties of the gel after drying, and it is beneficial to control the drying time and temperature.

The drying temperature of the gel is preferably dried at 100 ° C to 180 ° C. If the drying temperature is below 100 ° C, the drying time is too long and has no economic benefit. If it is dried above 180 ° C, the crosslinking agent will be used. The cross-linking reaction is carried out early so that the subsequent drying process, because the degree of crosslinking is too high, cannot effectively remove the residual monomers to reduce the residual monomer.

After drying, the powder is pulverized and sieved, and the fixed particle diameter is preferably between 0.06 mm and 1.00 mm, preferably between 0.10 mm and 0.850 mm, and the fine powder having a particle diameter of 0.06 mm or less is used to increase the finished dust. The particle size is 1.00 mm. The above particles slow down the water absorption rate of the finished product, and after screening the fixed particle diameter, the surface crosslinking agent coating treatment is performed.

The superabsorbent resin is an insoluble hydrophilic polymer, and has a bridge structure inside the resin. Generally, in order to improve the quality, such as: increasing the absorption rate, improving the strength of the colloid, improving the anti-caking property, liquid permeability, etc., the resin is The surface is further bridged. This surface crosslinking treatment utilizes a polyfunctional crosslinking agent capable of reacting with an acid group. Many patents have been disclosed before, such as dispersing superabsorbent resin and crosslinking. The surface crosslinking treatment is carried out in an organic solvent (Japanese Patent JP-A-56-131608, JP-A-57-44627, JP-A-58-42602, JP-A58-117222), and the inorganic powder is directly used. The crosslinking agent and the crosslinking agent solution are mixed with a super absorbent resin (Japanese Patent JP-A 60-163956, JP-A-60-255814), and the crosslinking agent is added and then treated with steam (Japanese Patent JP-A-1-113406) Surface treatment using an organic solvent, water, and a polyol (Japanese Patent JP-A-1-292004, US Pat. No. 6,346,569) and use of an organic solution, water, ether compound (Japanese Patent JP-A-2-153903) ), etc., these surface treatment methods can increase the absorption rate and increase the pressure. Water absorbency, but still keep the resulting decline in excessive force, and reduce the adverse consequences of the actual performance of the application.

According to the present invention, the crosslinking agent which can simultaneously react at the time of surface treatment is a polyhydric alcohol such as glycerin, ethylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol, propylene glycol, 1, 4 Butanediol, trimethylolpropane, sorbitol, etc.; or polyamines such as: ethylenediamine, diethylenediamine, triethylenediamine, polyethylenediamine; or having two or more epoxy Base compounds such as: sorbitol polyglycidyl ether, polyglycerol polyglycidyl ether, ethylene glycol diglycidyl ether, diethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, diglycerol poly Glycidyl ether, etc.; alkylene carbonate such as ethylene glycol carbonate, 4-methyl-1,3-dioxolane-2-one, 4,5-dimethyl-1, 3-dioxol-2-one, 4,4-dimethyl-1,3-dioxol-2-one, 4-ethyl-1,3-dioxole Alkan-2-one, 1,3-dioxan-2-one, 4,6-dimethyl-1,3-dioxan-2-one or 1,3-dioxo Heterocyclic heptane-2-one and the like.

The crosslinking agent may be used singly or in combination of two or more. The appropriate amount of the additive is between 0.001% by weight and 10% by weight based on the total solids of the reactants, more suitably between 0.005% and 5% by weight. The amount of the crosslinking agent additive cannot exhibit an effect at a weight percentage of 0.001% by weight or less; when the amount of the crosslinking agent additive is 10% by weight or more, the water absorption is too low to lower the resin property. At the stage of adding a crosslinking agent, polyvinyl alcohol may also be added at the same time, such as BP03, BP04, BP05, BP08 (Changchun chemical product), polyvinyl alcohol-1788 (Shanghai Meimenjia chemical product), PVA-10 (Wuxi gold) Silka Trading Company), polyvinyl alcohol -0588 (Shenzhen Hongxinyuan Chemical Products), etc. or polyethylene glycol such as PEG1000, PEG1500, PEG2000, PEG4000 (Donglian Chemical Products) for surface coating treatment, among which Suitable amounts of polyethylene glycol or polyvinyl alcohol are between 0.1% by weight and 10% by weight based on the total solids of the reactants, more suitably between 0.5% and 1% by weight. When the amount of the additive is less than 0.1% by weight by weight, the effect is not exhibited. When the amount of the additive is more than 10% by weight, the absorption of the superabsorbent resin after the coating treatment is poor and the economic performance is not good. .

After the superabsorbent resin is coated with the surface cross-linking agent, heat treatment is performed at a temperature ranging from 90 ° C to 230 ° C to enable the surface cross-linking agent and the internal cross-linking agent to uniformly and rapidly cross-link the reaction to achieve the present invention. The expected effect of the invention. When the heat treatment temperature is below 90 ° C, the crosslinking reaction time is too long and has no economic benefit. The heat treatment temperature is higher than 230 ° C and the resin is easily deteriorated to affect the quality. The invention is based on the purpose of obtaining a better surface treatment effect, and can be used for heat treatment temperature adjustment. When the heat treatment temperature is high, the heat treatment time is short, and when the heat treatment temperature is low, the heat treatment temperature is long, and the heat treatment time is preferably 30 minutes to 150 minutes. After this treatment, a highly water-absorptive resin excellent in absorption performance can be obtained.

The heat treatment apparatus suitable for the present invention includes a tunnel type mixing dryer, a drum type dryer, a table top dryer, a fluidized bed dryer, an air flow type dryer, and an infrared dryer.

The retention force of the present invention is tested by the measurement method disclosed in Chinese Patent No. CN 101433733A, and is tested in an environment at room temperature, and based on the average of two tests, firstly, about 0.2 +/- 0.005 g of the particles. The high water-absorbent resin with a diameter of 300-600 μm is sealed in a 3×5-inch rectangular tea bag, immersed in a 0.9% saline solution with a 4 cm height of the saline solution for 30 minutes, and then centrifuged at a diameter of 20 cm. Centrifuge at 1600 rpm for 3 minutes, and after using 2 tea bags as a blank, calculate the retention force by the following formula:

CRC=(W3-W2-W1)/W1

among them:

CRC = superabsorbent resin retention after 30 minutes of immersion

W1 = starting weight of superabsorbent resin

W2=Two blank average weights after centrifugation (two scales after the scale to the decimal point)

W3 = Test the weight of the tea bag after centrifugation (the scale is double digits after the decimal point).

The under load absorption (AUL) of the present invention uses the measurement method disclosed in Chinese Patent No. CN 101433733A, and the AUL measurement system is composed of the following components:

1. A plexiglass drum with a beveled edge with an inner diameter of 25 mm and a height of 33 mm, fitted with a 400 mesh (36 μm) size metal mesh at the bottom;

2. Plastic partition (diameter = 24 +/- 1 mm, weight 5.20 +/- 0.015 g);

3. Stainless steel code (diameter = 24 +/- 1 mm, weight of 98.35 +/- 0.05 g for AUL measurement at 0.3 psi pressure; 315.3 +/- 0.09 g for AUL measurement at 0.9 psi pressure) ;

4. Porous disc (from Knotes Glass, model number 9520001223);

5. Round filter paper (Whatman 3);

6. Petri dish (diameter = 150mm, height = 20mm);

7. Analyze the balance (requires an accuracy of 0.001g).

AUL analysis process:

First, place the porous disc in a petri dish. Before placing it, place the porous disc in 0.9% saline for more than one hour, then inject the saline into the Petri dish to make the liquid surface slightly lower than the porous circle. The tray was then placed on a porous disk and the saline solution was wetted, and 0.160 +/- 0.005 g of the super absorbent resin was uniformly fed into the metal mesh of the plexiglass drum, and the weight of the superabsorbent resin was recorded ( SA) Carefully place the plastic separator and the code into the plexiglass drum and record the weight of the complete unit (A). Place the entire set on the filter paper and allow it to absorb the brine for one hour. The entire process must be such that the brine level is slightly lower than the porous disk and the weight of the entire set is again weighed after one hour (B).

AUL calculation method: AUL (g/g) = (B-A) / SA of 0.3 psi or 0.9 psi

The invention is described in detail below with reference to the examples; however, the scope of the invention is not limited by the examples.

The 15 second free water absorption (FWA _{15 second} ) test of the present invention uses the measurement method disclosed in CN 101433733A to test the free water absorption of the super absorbent resin (SAP), and a vacuum device must be assembled first, to be more specific. The vacuum mercury was attached to the vacuum flask through a polyethylene tube, and the bottom of the porcelain funnel was placed on the top, the porcelain funnel and the flask were sealed by a single-hole rubber plug, a magnetic stirrer was placed beside the device, and the vacuum was connected. Mercury keeps it vacuum for _{15 seconds} throughout the FWA.

Using a 250 ml measuring cylinder, take 23.0 +/- 0.5 ° C tap water 150 ml +/- 0.1 ml, add to a 250 ml beaker containing a one-inch stir bar, and place the water-filled beaker on the stir plate to make the water produce a chaotropic liquid. A vortex of 2 to 3 cm. A dry 80 mesh (180 μm) screen was weighed and placed on top of the funnel, and then the vacuum mercury was started to press the screen until the screen was tightly fixed to the funnel; the scale was about 3.00+ on the aluminum pan. - 0.05 g of SAP, and incorporated into a vortex of stirred water, then start the stirrer for 15 seconds, then filter the wet polymer under a constant pressure of 5 inches Hg vacuum, and pay attention to the wet polymer transfer The screen with high water-absorbent resin is kept vacuum for 30 seconds in less than 3 seconds, then the screen and vacuum funnel are taken out, and the residual moisture in the lower part of the screen is wiped as much as possible with a paper towel, followed by a wet The screen of the superabsorbent resin was weighed, and the weight of the screen was subtracted from the total weight of the screen to determine the weight of the superabsorbent resin after moisture absorption, and the FWA value of _{15 seconds was} calculated by the following formula.

FWA _{15 seconds} (g/g) = (weight of superabsorbent resin after moisture absorption - weight of superabsorbent resin before moisture absorption) / weight of superabsorbent resin before moisture absorption

Reference example (prior art):

1) Add 100g of acrylic acid (produced by Formosa Plastics AE Factory) and 32.4g of water to the 100c.c conical flask; and weigh 24.3g of 48% sodium hydroxide solution in 100c.c conical flask, under ice cooling The sodium hydroxide aqueous solution was gradually added to the aqueous acrylic acid solution for neutralization; at this time, a monomer concentration of 42 wt% aqueous solution was obtained, and the neutralization ratio of the acrylic acid partial neutralization to sodium acrylate was 70 mol% (mol ratio).

2) Further, 0.046 g of glycerol polyethylene glycol triglycidyl ether (n = 7) was added to the partially neutralized acrylic acid solution, and the temperature was maintained at about 20 °C.

3) 0.016 g of L-ascorbic acid, 0.2 g of sodium persulfate and 0.2 g of 2.2-azobis(2-amidinopropane) dihydrochloride were added to initiate the reaction.

4) After the reaction, the superabsorbent resin was cut into a gel having a diameter of 2.00 mm or less by a cutter.

5) It is dried at a temperature of 130 ° C for 2 hours; after grinding, a fixed particle diameter of 0.1 mm to 0.85 mm is sieved by a sieve to obtain a powdery superabsorbent resin (a).

Embodiment 1:

1) Weigh 10g of superabsorbent resin (a), add 0.4g of ethylene carbonate/water = 1/1 (weight ratio) solution, mix with solid-liquid by mixer, and heat treatment at 215 °C for 30 minutes. ;

2) After cooling, the superabsorbent resin (b) having a holding force of 32.5 g/g and AUL (0.3 psi) = 33.3 g/g and AUL (0.9 psi) = 22.9 g/g;

3) The superabsorbent resin (b) was directly taken for evaluation of the absorption rate, and the results are shown in Table 1.

Embodiment 2:

1) Weigh 10g of superabsorbent resin (a), add 0.4g of ethylene carbonate/water = 1/1 (weight ratio) solution, and 0.05g of polyethylene glycol PEG1000 (average molecular weight 1000, Donglian Chemicals) Solid-liquid mixing by a mixer, and heat treatment at a temperature of 215 ° C for 30 minutes;

2) After cooling, the superabsorbent resin (c) having a holding force of 32.5 g/g and AUL (0.3 psi) = 33.1 g/g and AUL (0.9 psi) = 22.8 g/g;

3) The superabsorbent resin (c) was directly taken for evaluation of the absorption rate, and the results are shown in Table 1.

Embodiment 3:

1) Weigh 10g of superabsorbent resin (a), add 0.4g of ethylene carbonate/water = 1/1 (weight ratio) solution, and 0.1g of polyethylene glycol PEG1000 (average molecular weight of 1000, Donglian Chemicals) Solid-liquid mixing by a mixer, and heat treatment at a temperature of 215 ° C for 30 minutes;

2) After cooling, the superabsorbent resin (d) having a holding force of 32.3 g/g and AUL (0.3 psi) = 33.2 g/g and AUL (0.9 psi) = 22.9 g/g;

3) The superabsorbent resin (d) was directly taken for evaluation of the absorption rate, and the results are shown in Table 1.

Embodiment 4:

1) Weigh 10g of superabsorbent resin (a), add 0.4g of ethylene carbonate/water = 1/1 (weight ratio) solution, and 0.05g of polyethylene glycol PEG8000 (average molecular weight 8000, Donglian Chemicals) Solid-liquid mixing by a mixer, and heat treatment at a temperature of 215 ° C for 30 minutes;

2) After cooling, the superabsorbent resin (e) having a holding force of 32.1 g/g and AUL (0.3 psi) = 33.0 g/g and AUL (0.3 psi) = 22.7 g/g;

3) The superabsorbent resin (e) was directly taken for evaluation of the absorption rate, and the results are shown in Table 1.

Embodiment 5:

1) Weigh 10g of superabsorbent resin (a), add 0.4g of ethylene carbonate/water = 1/1 (weight ratio) solution, and 0.1g of polyethylene glycol PEG8000 (average molecular weight 8000, Donglian Chemicals) Solid-liquid mixing by a mixer, and heat treatment at a temperature of 215 ° C for 30 minutes;

2) After cooling, the superabsorbent resin (f) having a holding force of 32.3 g/g and AUL (0.3 psi) = 33.1 g/g and AUL (0.9 psi) = 22.9 g/g;

3) The superabsorbent resin (f) was directly taken for evaluation of the absorption rate, and the results are shown in Table 1.

Example 6:

1) Weigh 10g of superabsorbent resin (a), add 0.4g of ethylene carbonate/water = 1/1 (weight ratio) solution, and 0.05g of polyvinyl alcohol BP03 (average molecular weight 300, alcoholysis degree 86 mol) %~89mol%, Changchun Chemical Products) mixed with solid-liquid mixture, and then heat treated at 215 °C for 30 minutes;

2) After cooling, the superabsorbent resin (g) having a holding force of 32.1 g/g and AUL (0.3 psi) = 33.4 g/g and AUL (0.9 psi) = 23.0 g/g;

3) The superabsorbent resin (g) was directly taken for evaluation of the absorption rate, and the results are shown in Table 1.

Example 7:

1) Weigh 10g of superabsorbent resin (a), add 0.4g of glycol carbonate/water=1/1 (weight ratio) solution, and 0.1g of polyvinyl alcohol BP03 (average molecular weight 300, alcoholysis degree 86 mol) %~89mol%, Changchun Chemical Products) mixed with solid-liquid mixture, and then heat treated at 215 °C for 30 minutes;

2) After cooling, the superabsorbent resin (h) having a holding force of 32.0 g/g and AUL (0.3 psi) = 33.3 g/g and AUL (0.9 psi) = 22.9 g/g;

3) The superabsorbent resin (h) was directly taken for evaluation of the absorption rate, and the results are shown in Table 1.

Example 8:

1) Weigh 10g of superabsorbent resin (a), add 0.4g of ethylene carbonate/water = 1/1 (weight ratio) solution, and 0.05g of polyvinyl alcohol BP08 (average molecular weight of 800, alcoholysis degree 86 mol) %~89mol%, Changchun Chemical Products) mixed with solid-liquid mixture, and then heat treated at 215 °C for 30 minutes;

2) After cooling, the superabsorbent resin (i) having a holding force of 32.0 g/g and AUL (0.3 psi) = 33.2 g/g and AUL (0.9 psi) = 22.8 g/g;

3) The superabsorbent resin (i) was directly taken for evaluation of the absorption rate, and the results are shown in Table 1.

Example 9:

1) Weigh 10g of superabsorbent resin (a), add 0.4g of ethylene carbonate/water = 1/1 (weight ratio) solution, and 0.1g of polyvinyl alcohol BP08 (average molecular weight of 800, alcoholysis degree 86 mol) %~89mol%, Changchun Chemical Products) mixed with solid-liquid mixture, and then heat treated at 215 °C for 30 minutes;

2) After cooling, the superabsorbent resin (j) having a holding force of 32.3 g/g and AUL (0.3 psi) = 33.0 g/g and AUL (0.9 psi) = 22.9 g/g;

3) The superabsorbent resin (j) was directly taken for evaluation of the absorption rate, and the results are shown in Table 1.

Comparative example 1:

1) Weigh 10g of superabsorbent resin (a), add 0.4g of ethylene carbonate/water = 1/1 (weight ratio) solution, and 1.0g of polyethylene glycol PEG1000 (average molecular weight of 1000, Donglian Chemicals) Solid-liquid mixing by a mixer, and heat treatment at a temperature of 215 ° C for 30 minutes;

2) After cooling, the superabsorbent resin (k) having a holding force of 28.3 g/g and AUL (0.3 psi) = 27.2 g/g and AUL (0.9 psi) = 14.5 g/g;

3) The superabsorbent resin (k) was directly taken for evaluation of the absorption rate, and the results are shown in Table 1.

Comparative example 2:

1) Weigh 10g of superabsorbent resin (a), add 0.4g of ethylene carbonate/water = 1/1 (weight ratio) solution, and 1.0g of polyvinyl alcohol BP03 (average molecular weight 300, alcoholysis degree 86 mol) %~89mol%, Changchun Chemical Products) mixed with solid-liquid mixture, and then heat treated at 215 °C for 30 minutes;

2) After cooling, the superabsorbent resin (1) having a holding force of 29.1 g/g and AUL (0.3 psi) = 28.4 g/g and AUL (0.9 psi) = 15.1 g/g;

3) The superabsorbent resin (1) was directly taken for evaluation of the absorption rate, and the results are shown in Table 1.

Comparative example three:

1) According to the method of Chinese patent CN 101433733A, a super absorbent resin (b) having a holding force of 32.5 g/g and AUL (0.3 psi) = 33.3 g/g and AUL (0.9 psi) = 22.9 g/g is taken, and 2 g of a 50% Ca(NO ₃ ) ₂ aqueous solution was sprayed on the superabsorbent resin, and the resin was placed in a convection oven and dried at 100 ° C for one hour;

2) The superabsorbent resin after drying is ground and sieved with a mesh of 20 to 100 mesh to obtain a super absorbent resin (m), and the absorption speed and related physical properties of the superabsorbent resin are evaluated. The results are shown in Table 1.

Comparative Example 4:

1) According to the method of Chinese patent CN 101433733A, a super absorbent resin (b) having a holding force of 32.5 g/g and AUL (0.3 psi) = 33.3 g/g and AUL (0.9 psi) = 22.9 g/g is taken, and 2 g of a 50% aqueous solution of MgCl _{2 was} sprayed on the superabsorbent resin, and the resin was placed in a convection oven and dried at 100 ° C for one hour;

2) The superabsorbent resin after drying is ground and sieved with a mesh of 20 to 100 mesh to obtain a super absorbent resin (n), and the absorption speed and related physical properties of the superabsorbent resin are evaluated. The results are shown in Table 1.

Comparative Example 5:

1) Weigh 10g of superabsorbent resin (a), add 0.4g of ethylene carbonate/water = 1/1 (weight ratio) solution, and 0.05g of polyethylene glycol PEG10000 (average molecular weight 10000, Donglian Chemicals) Solid-liquid mixing by a mixer, and heat treatment at a temperature of 215 ° C for 30 minutes;

2) After cooling, the superabsorbent resin (o) having a holding force of 27.2 g/g and AUL (0.3 psi) = 26.3 g/g and AUL (0.9 psi) = 14.0 g/g;

3) The superabsorbent resin (o) was directly taken for evaluation of the absorption rate, and the results are shown in Table 1.

Comparative Example 6:

1) Weigh 10g of superabsorbent resin (a), add 0.4g of ethylene carbonate/water = 1/1 (weight ratio) solution, and 0.05g of polyvinyl alcohol BP28 (average molecular weight 2800, alcoholysis degree 86 mol) %~89mol%, Changchun Chemical Products) mixed with solid-liquid mixture, and then heat treated at 215 °C for 30 minutes;

2) After cooling, the superabsorbent resin (p) having a holding force of 27.3 g/g and AUL (0.3 psi) = 26.0 g/g and AUL (0.9 psi) = 14.2 g/g;

3) The superabsorbent resin (p) was directly taken for evaluation of the absorption rate, and the results are shown in Table 1.

It can be found from Examples 1 to 9 that when the superabsorbent resin is subjected to a coating treatment at the stage of surface modification in the manner of the present invention, a superabsorbent resin having a property of retarding absorption-related absorption property can be obtained, and The amount of the substance applied to the superabsorbent resin as a whole reaches 0.5% by weight of the resin, and the ability to absorb slowly is also improved; however, the superabsorbent resin treated in the manner of the patent CN 101433733A has a poor absorption property. It is expected that the superabsorbent resin produced in the manner of CN 101433733A requires more energy consumption and is cumbersome to process, and it is believed that the proposed embodiment of the present invention is expected to enhance the production process of the superabsorbent resin.

Claims (5)

A method for producing a superabsorbent resin, which comprises: (a) a superabsorbent resin particle having an internal crosslinked structure formed by radical polymerization of an aqueous acid monomer solution; (b) adding to the total resin a surface crosslinking agent in an amount of 0.001% by weight to 5% by weight and a surface coating agent in an amount of 0.5% by weight to 1% by weight based on the total amount of the resin, and then heat-treated at a temperature ranging from 90 ° C to 230 ° C to make the surface crosslinking agent and the interior The cross-linking agent is capable of uniformly and rapidly performing a surface crosslinking reaction as a manufacturing method characterized by the same. The method for producing a super absorbent resin according to claim 1, wherein the surface coating agent is selected from the group consisting of polyethylene glycol or polyvinyl alcohol. The method for producing a super absorbent resin according to claim 2, wherein the polyethylene glycol has a molecular weight of from 1,000 to 10,000. The method for producing a super absorbent resin according to claim 2, wherein the polyvinyl alcohol has a molecular weight of from 300 to 2,000. According to the method for producing a super absorbent resin according to the first aspect of the invention, the superabsorbent resin produced by the method has a retention of not less than 27 g/g after absorption by 0.9% saline, and AUL (absorption ratio under pressure) , 0.9 psi) not less than 14 g/g.