TWI466933B - 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 swelling after absorbing water. The state of no flow; no leakage even if pressure is applied, 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 for building materials, materials for removing moisture from petroleum or outer layer waterproofing coatings for cable and sanitary articles. 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 superabsorbent resin must have physical properties including absorption rate, absorption, absorption under pressure, low monomer residual amount, and gel strength after absorption. Excellent superabsorbent resin must not only be satisfied. The physical properties described in the column are of good safety and, more importantly, must be low in pollution and energy efficient.

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 can not be stored for a long time, and the manufacturing method thereof is also very complicated. Therefore, the general preparation method of the high water-absorbent resin is often used. Acrylic acid and/or acrylate of acid-based monomer is neutralized with NaOH to carry out cross-linking polymerization to produce superabsorbent resin. The main reason is that the raw material of acrylate copolymer-acrylic acid can be rapidly produced by industrial mass production. 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 common 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 water or absorbs, for example, 0.9% physiological saline, it starts to moisturize, and colloidal clogging occurs here. If the superabsorbent resin is under pressure load, its absorption capacity and flow rate will decrease. The ability to block the absorption of the superabsorbent resin that is not absorbed or is still being absorbed.

In response to this problem, Chinese patent CN1845948A has disclosed a superabsorbent resin with a hydrophobic substance, which can promote the absorption capacity and the liquid passing speed of the superabsorbent resin under pressure load. It is inferred that the reason for the increase of the liquid passing rate may be The particulate solid hydrophobic substance is added to increase the gap between the superabsorbent resin and the absorbing aqueous solution; however, the method of CN1845948A and the hydrophobic substance used are complicated and have low operational applicability.

[Technical means to solve the problem]

In view of the above, the inventors of the present invention have been able to produce a pass through long-term thinking, research and repeated tests, and experience at the work site, when it is found that an aqueous solution containing cerium oxide is added to the surface modification stage in the process of producing a superabsorbent resin. A resin with good liquid speed and absorbability. The particle size of the aqueous cerium oxide solution is between 20 and 250 nm, and the particle diameter is less than 20 nm, which tends to lower the flow rate of the superabsorbent resin. If the particle size is larger than 250 nm, the precipitation of the aqueous cerium oxide solution is likely to occur. The homogeneity of the aqueous solution containing cerium oxide is lowered, and the dispersibility and usability of the superabsorbent resin are lowered. The pH of the aqueous solution of cerium oxide is between 3 and 6 or between 8 and 11. If the pH is outside this range, the homogenization of the aqueous cerium oxide solution may be lowered, and the precipitation may be utilized. Decrease; the solid content of the aqueous solution of cerium oxide is preferably between 10% and 30%, and if less than 10%, the water to be added is increased, and the operability is lowered; if more than 30%, the aqueous solution is precipitated. The phenomenon reduces the homogeneity and usability.

SUMMARY OF THE INVENTION An object of the present invention is to provide a process for producing a superabsorbent resin which has excellent flow rate and absorption capacity under pressure.

Still another object of the present invention is to provide an aqueous solution containing cerium oxide having a hydrophobic substance, which is added in a surface modification stage of a process for producing a superabsorbent resin to produce a high water absorbing property with good liquid passing rate and absorption. Resin.

A hydrophilic resin representing an acrylic polymer having a hydrophilic functional group such as an acid group, a mercaptoamine group, an amino group and a sulfonic acid group on the hydrophilic resin polymer chain, and the hydrophilic resin of the present invention comprises: Polyacrylic acid or a salt thereof which contains an alkali metal cation salt or an ammonium salt such as lithium, sodium or potassium, and a polymer of the above two, and the neutralization ratio of the neutralized acrylic acid (ie, partial neutralization of acrylic acid) It becomes 30 to 70 mol% as an acrylate. In addition, the above two may be copolymerized with a water-soluble or water-insoluble monomer, and the water-soluble or insoluble monomer may be methacrylic acid, maleic acid, fumaric acid, crotonic acid, itaconic acid, vinyl sulfonate. Acid, 2-(meth)acrylamide amine-2-methylpropane sulfonic acid, (meth) propylene decyloxy alkane sulfonic acid, and the associated alkali metal cation salt or ammonium salt, etc. Monomers such as vinyl acetamide, (meth) acrylamide, N, N-dimethyl acrylamide.

When the present invention uses a monomer other than 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 water-absorbent resin is prepared by adding a radical polymerization crosslinking agent to a radical reaction in an unreacted monomer solution before the radical polymerization reaction, and the radical polymerization crosslinking agent may be selected from two or a compound having two or more unsaturated double bonds, such as: N,N'-bis(2-propenyl)amine, N,N'-methacrylic bis decylamine, N,N'-methine bismethyl Acrylamide, propylene acrylate, ethylene glycol diacrylate, polyethylene glycol diacrylate, ethylene glycol dimethacrylate, polyethylene glycol dimethacrylate, glycerin triacrylate, glycerol trimethacrylate Acrylate, glycerin plus ethylene oxide triacrylate or trimethacrylate, trimethylolpropane plus ethylene oxide triacrylate or trimethacrylate, trimethylolpropane trimethacrylate, three Methanol propane triacrylate, N,N,N-tris(2-propenyl)amine, ethylene glycol diacrylate, polyoxyethylene glyceryl triacrylate, diethyl polyoxyethylene glyceryl triacrylate, dipropylene Glycol 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, and the appropriate amount of the additive is between 0.001% by weight and 5% by weight based on the total solids of the reactants, and a more appropriate weight percentage is Between 0.01% by weight and 3% by weight, the amount of the additive is 0.001% by weight or less, the hydrated body after polymerization is too soft and sticky, and the amount of the additive is too low, and the amount of the additive is too low, and the amount of the additive is lower than 5% by weight. The performance of water absorbent resin.

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 from 0.001% by weight to 10% by weight based on the weight of the neutralized acrylate, and more suitably from 0.1% by weight to 5% by weight. When the weight percentage is 0.001% by weight or less, the reaction is too slow, which is unfavorable economical efficiency. When the weight percentage is 10% by weight or more, the reaction is too fast and the heat of reaction is not easily controlled.

The polymerization can be carried out in a conventional batch reaction vessel or on a conveyor belt reactor. 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 sieved. 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 above acrylate gel, the better the physical properties of the gel after drying, and the drying time and temperature are controlled.

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. The fine powder having a particle diameter of 0.06 mm or less improves the finished dust; the particle diameter of 1.00 mm or more makes the water absorption rate of the finished product slow, and after screening the fixed particle diameter, the surface crosslinking agent is applied.

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, that is, the use of a polyfunctional crosslinking agent capable of reacting with an acid group, has been disclosed in the prior art; for example, dispersing superabsorbent resin and The crosslinking agent is subjected to surface crosslinking treatment in an organic solvent (JP-A-56-131608, JP-A-57-44627, JP-A-58-42602, JP-A58-117222), and the crosslinking is directly carried out using an inorganic powder. The agent and the crosslinking agent solution are mixed with a superabsorbent resin (JP-A60-163956, JP-A-60-255814), and after adding a crosslinking agent, it is treated with steam (JP-A-1-113406), using an organic solvent, Water and polyol are surface-treated (JP-A-1-292004, US Pat. No. 6,346,569) and organic solution, water, ether compound (JP-A-2-153903), etc., although these surface treatment methods can Increase the absorption rate and increase the water absorption rate under pressure, but it still causes excessive retention and Adverse consequences of the low performance of practical 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.; also alkylene carbonate such as: ethylene glycol carbonate, 4-methyl-1,3-dioxolane-2-one, 4,5-dimethyl-1,3- Dioxolane-2-one, 4,4-dimethyl-1,3-dioxol-2-one, 4-ethyl-1,3-dioxolane- 2-keto, 1,3-dioxan-2-one, 4,6-dimethyl-1,3-dioxan-2-one or 1,3-dioxe Heptan-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. The invention finds that the surface of the crosslinking agent is added at the same time, and the surface crosslinking treatment (modification) agent and the aqueous solution containing cerium oxide are added for surface modification, and the liquid passing speed and absorption capacity of the super absorbent resin can be effectively improved. . A suitable additive amount of this aqueous cerium oxide solution is between 0.1% by weight and 10% by weight based on the total solids of the reactants, more suitably between 0.1% and 2% by weight. The amount of the additive of the aqueous cerium oxide solution cannot exhibit an effect at a weight percentage of 0.1% by weight or less, and the amount of the additive at a weight percentage of 2% by weight or more may lower the properties of the resin and its absorption performance.

The superabsorbent resin is subjected to surface crosslinking agent coating and addition of an aqueous solution of cerium oxide, and then heat-treated at a temperature ranging from 90 ° C to 230 ° C to uniformly and rapidly carry out the surface crosslinking agent and the internal crosslinking agent. The crosslinking reaction is carried out to achieve the intended effects of the present invention. Since the heat treatment temperature is below 90 ° C, the crosslinking reaction time is too long to be economical, and the heat treatment temperature is above 230 ° C. 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 superabsorbent resin having a preferred liquid passing rate and excellent 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.

In order to show the water absorption capacity under pressure under the superabsorbent resin of the present invention, the present invention is measured using a pressure-absorbing absorption weight (pressure load: 20 g/cm ² and 49 g/cm ² ). The amount of pressure absorption is determined according to the method described on the seventh page of the specification of European Patent No. 0339461 A; the powder of the superabsorbent resin of the initial weight is placed in a cylinder having a bottom of the sieve to be 20 g/cm ² and 49 g / The pressure of cm ² is then placed on the absorption demand tester, and the superabsorbent resin powder is absorbed by 0.9% sodium chloride aqueous solution for one hour, and the measured water absorption weight value is divided by high water absorption. The initial weight of the resin is the value of the pressure absorbed weight.

The retention force of the present invention is the measurement method disclosed in CN 1845948A, which is added to a tea bag (length 20 cm, width 10 cm) made of a 250 mesh nylon mesh, and 1.00 g of the test sample is added, without stirring. The suspension was placed in 1000 mL of 0.9% physiological saline for 1 hour. After hanging for 15 minutes, the tea bag was placed in a centrifuge and centrifuged at 150 G for 90 seconds. After removing the remaining physiological saline, the weight of the tea bag was measured, and The retention force (X) was determined by the following formula, and the physiological saline used and the test ambient temperature were 25 ° C ± 2 ° C.

(X)={h1-h2-1.00}/1.00

H2 is the weight of the tea bag containing no test sample as determined by the same operating conditions as above.

The flow rate of the present invention is also measured by the method disclosed in CN 1845948A, in which 0.32 g of the sample to be tested is statically placed in 50 mL of physiological saline for 1 hour to obtain an aqueous gel particle, and further, with a plug and a capacity scale. The plug (ID = 25.4 mm, length 35 cm) of the closed column (screen: 10~15um) is closed (ID=5 mm, length 10 cm) and the vertical ground of the plug is fixed. On the column, the aforementioned hydrogel particles are poured into the above-mentioned column together with physiological saline, and a circular wire mesh (diameter of 150 um (JIS Z8801:2000)) is vertically provided at one end of the column. A 25 mm) pressurizing shaft (weight: 15.5 g, length 31.5 cm) was placed in such a manner that the wire mesh was placed on one side of the aqueous gel particles, and a weight (91.5 g) was placed and allowed to stand for one minute.

Open the plug under the column to reduce the measured liquid level from 60 mL to 40 mL (T1: sec.), then calculate the flow rate (Y, mL/min) using the following formula. And the test ambient temperature is 25 ° C ± 2 ° C.

Y=20(mL)x60/(T1-T2)

(T2) is the time required for the sample to pass the above operating conditions, that is, the time required for the liquid to be lowered from 60 mL to 40 mL after the column is added with physiological saline.

The invention is described in detail below with reference to preferred embodiments but the scope of the invention is not limited by the examples.

The aqueous cerium oxide solution used in the present invention:

1) Take 30 grams of cerium oxide and 269 gram of water produced by Wacker, and add 1N hydrochloric acid aqueous solution to 1 gram after mixing, to obtain cerium oxide with a solid content of 10% and a pH of 3.2. Aqueous solution (a)

2) Take 30 grams of cerium oxide and 269 grams of water produced by Wacker Company as H2050EP. After mixing and adding 1 gram of 1N sodium hydroxide solution, the solid form is 10% and the pH is 10.5 bis. Aqueous yttrium oxide solution (b)

3) Take the aqueous solution of cerium oxide produced by Wacker Company as D2012B. This aqueous solution is 12% solid solution and 4.6 aqueous solution of cerium oxide (c)

4) Take the aqueous solution of cerium oxide produced by Wacker Company as A3017. This aqueous solution is a solid solution of 17% and a pH of 10.3 cerium dioxide solution (d).

5) Take 90 grams of cerium oxide and 209.5 gram of water produced by Wacker Co., Ltd., and add 0.5N of 1N aqueous hydrochloric acid solution after mixing evenly to obtain cerium oxide with a solid content of 30% and a pH of 3.4. Aqueous solution (e)

6) Take 90 grams of cerium oxide and 209.5 gram of water produced by Wacker Company as H2050EP. After mixing and adding 0.5 gram of 1N sodium hydroxide solution, the solid type is 30% and the pH is 10.7. Aqueous yttrium oxide solution (f)

7) Take AZ Electronic Materials' product Klebosol model is 30CAL50 of cerium oxide aqueous solution, this aqueous solution is 30% solid solution, pH 4.2 cerium dioxide aqueous solution (g)

8) Take the aqueous solution of cerium oxide produced by Wacker Co., Ltd. model XK20030, this aqueous solution is 30% solid solution, and the aqueous solution of cerium oxide having a pH of 10.5 (h)

The pH values described above were all measured by a METTLER TOLEDO T70 automatic titrator from METTLER.

Embodiment 1: (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 is gradually added to the aqueous solution of acrylic acid for neutralization; at this time, a monomer concentration of 42 wt% aqueous solution is obtained, wherein the neutralization ratio of the acrylic acid partial neutralization to sodium acrylate is 70 mol% (mole ratio);

2) adding 0.046 g of glycerol polyethylene glycol triglycidyl ether (n = 7) to the partially neutralized acrylic acid solution, and maintaining the temperature at about 20 ° C;

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

4) After the reaction, the aqueous gel (A) is cut into a gel having a diameter of 2 mm or less by a cutter mill;

5) drying at 130 ° C for 2 hours; after grinding, using a sieve to screen a fixed particle size of 0.1mm ~ 0.85mm, to obtain a powdery superabsorbent resin (A);

Embodiment 2:

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

2) After cooling, the holding capacity of 35.5g / g, water absorption ratio of 30.1g / g under pressure of 20g / cm ² , water absorption capacity of 22.8g / g under pressure of 49g / cm ² (B);

3) The superabsorbent resin (B) was directly taken to evaluate the flow rate under pressure, and the results are shown in Table 1.

Embodiment 3:

1) Weigh 100g of superabsorbent resin (A), add 4.0g of ethylene carbonate/water = 1/1 (weight ratio) solution and 2.0g of cerium dioxide solution (a), and mix it by solid-liquid mixing machine. And heat treatment at 215 ° C for 10 minutes;

2) After cooling, a holding power of 35.2 g/g, a water absorption capacity of 30.3 g/g under a pressure of 20 g/cm ² , and a water-absorbent capacity (C) having a water absorption ratio of 23.0 g/g under a pressure of 49 g/cm ² were obtained, and The superabsorbent resin (C) was evaluated for the flow rate under the pressure, and the results are shown in Table 1.

Embodiment 4:

1) Weigh 100g of superabsorbent resin (A), add 4.0g of ethylene carbonate/water = 1/1 (weight ratio) solution and 2.0g of cerium dioxide solution (b), and mix it with liquid and liquid. And heat treatment at 215 ° C for 10 minutes;

2) After cooling, the holding capacity is 35.1 g/g, the water absorption capacity is 30.5 g/g under a pressure of 20 g/cm ² , and the super absorbent resin (D) having a water absorption ratio of 23.1 g/g under a pressure of 49 g/cm ^{2 is} obtained. The superabsorbent resin (D) was subjected to evaluation of the flow rate under pressure, and the results are shown in Table 1.

Embodiment 5:

1) Weigh 100g of superabsorbent resin (A), add 4.0g of ethylene carbonate/water = 1/1 (weight ratio) solution and 2.0g of ceria solution (c), and mix it with liquid and liquid. And heat treatment at 215 ° C for 10 minutes;

2) After cooling, the holding capacity is 35.3 g/g, the water absorption capacity is 30.5 g/g under a pressure of 20 g/cm ² , and the water-absorbent resin (E) having a water absorption ratio of 23.3 g/g under a pressure of 49 g/cm ^{2 is} obtained. The superabsorbent resin (E) was subjected to evaluation of the liquid flow rate under pressure, and the results are shown in Table 1.

Example 6:

1) Weigh 100g of superabsorbent resin (A), add 4.0g of glycol carbonate/water=1/1 (weight ratio) solution and 2.0g of cerium dioxide solution (d), and mix it with liquid and liquid. And heat treatment at 215 ° C for 10 minutes;

2) After cooling, the holding capacity is 35.0 g/g, the water absorption ratio is 30.1 g/g under a pressure of 20 g/cm ² , and the water-absorbent resin (F) having a water absorption ratio of 23.2 g/g under a pressure of 49 g/cm ^{2 is} obtained. The superabsorbent resin (F) was subjected to evaluation of the flow rate under pressure, and the results are shown in Table 1.

Example 7:

1) Weigh 100g of superabsorbent resin (A), add 4.0g of ethylene carbonate/water = 1/1 (weight ratio) solution and 2.0g of cerium dioxide solution (e), and mix it with liquid and liquid. And heat treatment at 215 ° C for 10 minutes;

2) After cooling, the holding capacity is 35.2 g/g, the water absorption ratio is 30.2 g/g under a pressure of 20 g/cm ² , and the super absorbent resin (G) having a water absorption ratio of 23.0 g/g under a pressure of 49 g/cm ^{2 is} obtained. The superabsorbent resin (G) was subjected to evaluation of the flow rate under pressure, and the results are shown in Table 1.

Example 8:

1) Weigh 100g of superabsorbent resin (A), add 4.0g of glycol carbonate/water=1/1 (weight ratio) solution and 2.0g of cerium dioxide solution (f), and mix it with liquid and liquid. And heat treatment at 215 ° C for 10 minutes;

2) After cooling, the holding capacity is 35.5 g/g, the water absorption ratio is 30.2 g/g under a pressure of 20 g/cm ² , and the water-absorbent resin (H) having a water absorption ratio of 23.0 g/g under a pressure of 49 g/cm ^{2 is} obtained. The superabsorbent resin (H) was subjected to evaluation of the flow rate under pressure, and the results are shown in Table 1.

Example 9:

1) Weigh 100g of superabsorbent resin (A), add 4.0g of glycol carbonate/water=1/1 (weight ratio) solution and 2.0g of cerium dioxide solution (g), and mix it with liquid and liquid. And heat treatment at 215 ° C for 10 minutes;

2) After cooling, the holding capacity is 35.1 g/g, the water absorption capacity is 30.3 g/g under a pressure of 20 g/cm ² , and the water-absorbent resin (I) having a water absorption ratio of 22.9 g/g under a pressure of 49 g/cm ^{2 is} obtained. The superabsorbent resin (I) was subjected to evaluation of the flow rate under pressure, and the results are shown in Table 1.

Example 10:

1) Weigh 100g of superabsorbent resin (A), add 4.0g of ethylene carbonate/water = 1/1 (weight ratio) solution and 2.0g of aqueous ceria solution (h), and mix it with liquid and liquid. And heat treatment at 215 ° C for 10 minutes;

2) After cooling, a holding power of 35.4 g/g, a water absorption capacity of 30.2 g/g under a pressure of 20 g/cm ² and a water absorption capacity of 23.0 g/g under a pressure of 49 g/cm ² (J) are obtained. The superabsorbent resin (J) was subjected to evaluation of the flow rate under pressure, and the results are shown in Table 1.

Example 11:

1) Weigh 100g of superabsorbent resin (A), add 4.0g of polyethylene glycol diglycidyl ether / water = 1 / 1 (weight ratio) solution, mix solid-liquid mixture with a mixer, and then heat at 215 ° C Processing for 10 minutes;

2) After cooling, a superabsorbent resin (K) having a holding power of 35.2 g/g, a water absorption ratio of 30.3 g/g under a pressure of 20 g/cm ² and a water absorption ratio of 22.9 g/g under a pressure of 49 g/cm ² was obtained.

3) The superabsorbent resin (K) was directly taken to evaluate the flow rate under pressure, and the results are shown in Table 1.

Example 12:

1) Weigh 100g of superabsorbent resin (A), add 4.0g of polyethylene glycol diglycidyl ether/water=1/1 (weight ratio) solution and 4.0g of cerium dioxide solution (a), and mix it with a mixer. Solid-liquid mixing, and then heat treatment at 215 ° C for 10 minutes;

2) After cooling, the holding capacity is 35.0 g/g, the water absorption capacity is 30.0 g/g under a pressure of 20 g/cm ² , and the water-absorbent resin (L) having a water absorption ratio of 22.9 g/g under a pressure of 49 g/cm ^{2 is} obtained. The superabsorbent resin (L) was subjected to evaluation of the flow rate under pressure, and the results are shown in Table 1.

Example 13:

1) Weigh 100g of superabsorbent resin (A), add 4.0g of polyethylene glycol diglycidyl ether/water=1/1 (weight ratio) solution and 4.0g of cerium dioxide solution (b), and mix it with a mixer. Solid-liquid mixing, and then heat treatment at 215 ° C for 10 minutes;

2) After cooling, a superabsorbent resin (M) having a holding power of 35.0 g/g, a water absorption ratio of 30.2 g/g under a pressure of 20 g/cm ² and a water absorption ratio of 23.0 g/g under a pressure of 49 g/cm ^{2 is} obtained. The superabsorbent resin (M) was subjected to evaluation of the flow rate under pressure, and the results are shown in Table 1.

Embodiment 14:

1) Weigh 100g of superabsorbent resin (A), add 4.0g of polyethylene glycol diglycidyl ether/water=1/1 (weight ratio) solution and 4.0g of ceria solution (c), using a mixer Solid-liquid mixing, and then heat treatment at 215 ° C for 10 minutes;

2) After cooling, the holding capacity is 35.3 g/g, the water absorption ratio is 30.3 g/g under a pressure of 20 g/cm ² , and the water-absorbent resin (N) having a water absorption ratio of 22.9 g/g under a pressure of 49 g/cm ^{2 is} obtained. The superabsorbent resin (N) was subjected to evaluation of the flow rate under pressure, and the results are shown in Table 1.

Example 15:

1) Weigh 100g of superabsorbent resin (A), add 4.0g of polyethylene glycol diglycidyl ether / water = 1 / 1 (weight ratio) solution and 4.0g of aqueous ceria solution (d), using a mixer Solid-liquid mixing, and then heat treatment at 215 ° C for 10 minutes;

2) After cooling, the holding capacity is 35.1 g/g, the water absorption capacity is 30.1 g/g under a pressure of 20 g/cm ² , and the water-absorbent resin (O) having a water absorption ratio of 23.1 g/g under a pressure of 49 g/cm ^{2 is} obtained. The superabsorbent resin (O) was subjected to evaluation of the flow rate under pressure, and the results are shown in Table 1.

Example 16:

1) Weigh 100g of superabsorbent resin (A), add 4.0g of polyethylene glycol diglycidyl ether/water=1/1 (weight ratio) solution and 4.0g of cerium dioxide solution (e), and mix it with a mixer. Solid-liquid mixing;

2) After mixing, the holding power is 35.0 g/g, the water absorption capacity is 30.1 g/g under a pressure of 20 g/cm ² , and the water-absorbent resin (P) having a water absorption ratio of 22.9 g/g under a pressure of 49 g/cm ^{2 is} obtained. The superabsorbent resin (P) was subjected to evaluation of the flow rate under pressure, and the results are shown in Table 1.

Example 17:

1) Weigh 100g of superabsorbent resin (A), add 4.0g of polyethylene glycol diglycidyl ether/water=1/1 (weight ratio) solution and 4.0g of cerium oxide solution (f), and mix it with a mixer. Solid-liquid mixing;

2) After mixing, the holding capacity is 35.0 g/g, the water absorption capacity is 30.0 g/g under a pressure of 20 g/cm ² , and the water-absorbent resin (Q) having a water absorption ratio of 23.0 g/g under a pressure of 49 g/cm ^{2 is} obtained. The superabsorbent resin (Q) was evaluated for the flow rate under pressure, and the results are shown in Table 1.

Example 18:

1) Weigh 100g of superabsorbent resin (A), add 4.0g of polyethylene glycol diglycidyl ether/water=1/1 (weight ratio) solution and 4.0g of cerium dioxide solution (g), and mix it with a mixer. Solid-liquid mixing;

2) After mixing, the holding capacity is 35.3 g/g, the water absorption ratio is 30.1 g/g under a pressure of 20 g/cm ² , and the super absorbent resin (R) having a water absorption ratio of 23.1 g/g under a pressure of 49 g/cm ^{2 is} obtained. The superabsorbent resin (R) was subjected to evaluation of the flow rate under pressure, and the results are shown in Table 1.

Example 19:

1) Weigh 100g of superabsorbent resin (A), add 4.0g of polyethylene glycol diglycidyl ether / water = 1 / 1 (weight ratio) solution and 4.0g of aqueous solution of cerium oxide (h), using a mixer Solid-liquid mixing;

2) After mixing, the holding capacity is 35.0 g/g, the water absorption capacity is 30.3 g/g under a pressure of 20 g/cm ² , and the super absorbent resin (S) having a water absorption ratio of 23.0 g/g under a pressure of 49 g/cm ^{2 is} obtained. The superabsorbent resin (S) was subjected to evaluation of the liquid flow rate under pressure, and the results are shown in Table 1.

Comparative example 1:

The superabsorbent resin gel (A) of Example 1 was added to 40 parts of the hydrophobic material in 400 parts (CN 1845948A, Example 6: 0.0005 parts of Sanyo Chemical Co., Ltd. product SANWAX 165-P) was dissolved in 10 parts. In cyclohexane, 5 parts of cerium oxide "Aerosil 200 PE" produced by Japan Aerosil Co., Ltd. was added, and the mixture was stirred at 25 ° C for two minutes using Biomixer, then dried at 60 ° C for 1 hour to obtain a hydrophobic material, and diffused. 0.4 parts (SANMORIN OT 70 manufactured by Sanyo Chemical Co., Ltd.) was placed in a chopper for 5 minutes, and then placed on a vented belt dryer to dry at a temperature of 135 ° C and a wind speed of 2 m / sec. The product is further pulverized by a commercially available juice extractor to obtain a super absorbent resin (T), sieved through a sieve having a mesh opening of 0.25 mm to 0.6 mm, and then 100 parts of the above-mentioned sieved superabsorbent resin is sprayed in a high speed mixer. 2 parts of diol diglycidyl ether 10% water/methanol mixture (water/methanol weight ratio = 7/3), and then heating to obtain a holding force of 35.0 g / g, 20 g / cm ² pressure under water absorption ratio of 30.1 g water absorption ratio 22.9g / g of superabsorbent polymer (T), takes this superabsorbent polymer (T) under a ^pressure / g, 49g / cm for Through rate estimates under pressure, a result as shown in Table.

Comparative example 2:

The super absorbent resin (T) is sieved through a sieve having a mesh opening of 0.15 mm to 0.85 mm, and 100 parts of the above-mentioned sieved superabsorbent resin is sprayed with 2 parts of the diol diglycidyl ether 10 in a high speed mixer. % water/methanol mixture (water/methanol weight ratio = 7/3), and then heated to obtain a holding force of 35.2 g/g and a water absorption ratio of 30.0 g/g under a pressure of 20 g/cm ² and a water absorption under a pressure of 40 g/cm ² The superabsorbent resin (U) having a rate of 22.8 g/g was taken, and the superabsorbent resin (U) was taken to evaluate the flow rate under pressure, and the results are shown in Table 1.

From the results of the examples and Table 1, it can be found that whether the added aqueous solution of cerium oxide is self-adapted or is a commercialized aqueous solution of cerium oxide, the desired target for increasing the flow rate under pressure can be achieved, and There is no significant negative impact on the physical properties of the absorption ratio under retention and pressure. Comparing the superabsorbent resin of the present invention with CN 1845948A, the superabsorbent resin under pressure of the present invention performs much better than the performance described in CN 1845948A, and the superabsorbent resin disclosed in CN 1845948A. The manufacturing method does not mention the absorption magnification performance under excellent pressure, and there is no performance report that the superabsorbent resin of the present invention has an excellent liquid passing speed under pressure.

The present inventors have found that when the surface of the superabsorbent resin is easily dust-producing, the surface modification is carried out by adding an aqueous ceria solution to enhance the physical properties of the superabsorbent resin, thereby effectively reducing the dust generated by the process. And to enhance the production operability of the super absorbent resin, thereby promoting the development of the superabsorbent resin production process.

Claims (3)

A method for producing a super absorbent resin, comprising: (a) in a superabsorbent resin particle having an internal crosslinked structure formed by radical polymerization of an aqueous solution containing an acid group; (b) adding a method for producing a surface crosslinking agent having a total amount of 0.001% by weight to 5% by weight of the resin and a surface crosslinking reaction agent comprising 0.1% by weight to 2% by weight of the total amount of the aqueous solution of the cerium oxide solution; The particle size of the cerium oxide particles of the speed promoter is between 20 and 250 nm. The method for producing a super absorbent resin according to claim 1, wherein the crosslinking agent is selected from the group consisting of ethylene glycol carbonate and polyethylene glycol diglycidyl ether. The method for producing a super absorbent resin according to claim 1, wherein the pH of the aqueous solution of the cerium oxide solution of the liquid passing rate accelerator is between 3 and 6 or 8 to 11.