TWI495674B - Process for the production of a superabsorbent polymer - Google Patents

Description

Method for producing super absorbent resin

Superabsorbent resins are widely used in water retaining agents for agriculture or horticulture, anti-dew beading agents in building materials, and materials for removing moisture from petroleum, or outer layer waterproofing agents in cable and sanitary articles, such as Diapers, feminine hygiene products, disposable wipes, etc., are especially used in diapers.

Ultra-thin diapers are currently the most important development direction because ultra-thin diapers must have a high-density absorbing layer, and the superabsorbent resin and pulp fiber mixture of such an absorbing layer must have higher absorption capacity. In order to make full use of the ability of the absorbing layer to store liquid, the distribution of liquid in the absorbing layer becomes very important. In general, the reduction of pulp fibers in the absorbent layer can have a negative impact on the distribution of liquid in the absorbent layer.

When the superabsorbent resin or the pulp fiber in the absorbing layer absorbs the liquid, the voids in the superabsorbent resin and the pulp fiber or the pores in the superabsorbent resin are closed because of rapid expansion, thereby suppressing the liquid. Conduction, causing the subsequent liquid to no longer penetrate the area that has been absorbed by the liquid and expand. This phenomenon is called gel-blocking; when this happens, the liquid can no longer penetrate the absorber, but Edge flow causes leakage to occur.

In addition, the superabsorbent resin near the expanded region is colloidally clogged, and the remaining liquid cannot reach the deeper portion, so that the ability of the absorbent layer to store liquid is greatly reduced.

It is known in the art that the method of reducing colloidal clogging is to change the rate of absorption of the superabsorbent resin (U.S. Patent No. 4,548,847), the disclosure of which is incorporated herein by reference to the utility of the "Cationic Complexing Agent" such as sodium hexametaphosphate, ethylene a water-soluble compound such as an amine tetraacetic acid disodium salt or ammonium hydrogen phosphate, and a hydrogel body containing at least one divalent metal ion, which is a high water-absorbent resin by reducing the crosslinking density in the hydrogel body. It is easier to absorb liquids.

EP 0 631 768 A1 mentions an absorbent body which utilizes superabsorbent resins of different particle size distributions (type 1 having a particle size range of from 600 to 850 um and type 2 having a particle size range of less than 250 um), further producing Absorbers with different absorption velocities, however, the difference in absorption speed is not large.

U.S. Patent No. 5,115,011 discloses the use of a sulfate, acetate or nitrate compound having aluminum, calcium or magnesium, and a monovalent metal salt or ammonium salt compound of sulfurous acid, mixed in an amount of less than 10 parts by weight to reduce colloidal clogging. happened.

An absorbent for absorbing blood and liquid is also mentioned in the above-mentioned U.S. Patent No. 5,115,011, which uses a mixture of a superabsorbent resin and a halogen compound having a phosphate group, a sulfite group or a sulfate group. The sexual mixture (stored at room temperature in the form of a flowing powder, which is harmless to the living body) is dissolved in an unsaturated monomer to carry out polymerization, and thus, the diffusion speed of the liquid can be increased.

In addition, the use of a water-soluble anionic compound having a carboxylic acid group, a sulfonic acid group, and a phosphoric acid group and a polyvalent metal having a valence of at least 3, such as an antimony, can also reduce colloidal blocking. Occurs (US Patent 5,578,318).

Further, a polyvalent metal salt solution using citrate or sulfate is mixed with a superabsorbent resin, and although a superabsorbent resin having a low absorption rate can be produced, it cannot be obtained by secondary processing, resulting in a drastic reduction in production. Efficiency (US Patent 6,433,058, 6,579,958).

The polyol compound and the carbonate compound are mixed and granulated in a fluid-bed spray granulator dryer, and then added to the unsaturated monomer to carry out polymerization reaction, so that the absorption rate of the liquid can be increased, but the rate of absorption of the liquid can be increased. Coating with a polyol compound, that is, the superabsorbent resin produced by this method is prone to yellow-coloring change, and must be mixed by a fluidized layer spray granulation dryer for about 60 to 120 minutes. Obtained, resulting in a significant reduction in production efficiency (US Patent 7,163,966).

[Problems to be solved by the invention]

Ultra-thin diapers must have a high-density absorbent layer, especially for absorbent bodies with multiple layers of absorbent layers, to prevent the occurrence of colloidal clogging, which is an important issue. One of the methods for solving this problem is to infiltrate a superabsorbent resin having a slower speed or a fast absorption speed in the absorbent body. However, the above-mentioned method cannot produce a satisfactory superabsorbent resin.

In view of the above, an object of the present invention is to provide a super absorbent resin which has a fast absorption speed and a high absorption ratio characteristic under high pressure, and further, the super absorbent resin produced by the present invention has a fast liquid The absorption rate, the 0.9% sodium chloride aqueous solution vortex disappearance index is not more than 35 sec/g, and the water absorption ratio under the pressure of 49 g/cm ^{2 is} not less than 12 g/g.

[Technical means to solve the problem]

According to the present invention, the method for producing a superabsorbent resin having a rapid absorption rate according to the present invention comprises at least: (1) an acid group-containing monomer in an aqueous solution of an acid group-containing monomer having a neutralization ratio of 45 mol% or more. Selecting from a mixture of acrylic acid or methacrylic acid or 2-propenylamine-2-methylpropanesulfonic acid or the above group; (2) adding a radical polymerization reaction by a coating-treated blowing agent and a polymerization initiator Producing a superabsorbent resin gel; (3) shearing the hydrogel into a small hydrogel; (4) drying, pulverizing, and screening the gel at a temperature of 100 ° C to 250 ° C; (5) Finally, a surface crosslinking reaction is carried out on the surface of the super absorbent resin.

The above is a method for producing a superabsorbent resin having a high absorption rate and a high absorption ratio at a high pressure, wherein the coating-treated foaming agent used for the polymerization reaction is a carbonate compound, And a mixture of alum compounds, the ratio of the carbonate compound to the alum compound is 5:95 to 95:5, and the carbonate compound has a carbonate or hydrogencarbonate compound in a chemical structure, such as sodium carbonate or potassium carbonate. , ammonium carbonate, magnesium carbonate, calcium carbonate, barium carbonate, sodium hydrogencarbonate, potassium hydrogencarbonate, ammonium hydrogencarbonate, magnesium hydrogencarbonate, calcium hydrogencarbonate or barium hydrogencarbonate. The alum compound is a compound containing crystal water, such as potassium alum, sodium alum or ammine.

In general, in addition to acrylic acid, other water-soluble monomers having an unsaturated double bond having an acidic group, such as methacrylic acid, malic acid, and fuma, can be used in addition to acrylic acid. Acid, 2-propenylamine-2-methylpropanesulfonic acid, maleic acid, maleic anhydride, fumaric acid, fumaric anhydride, and the like. The monomer may be used in a single type, and may be used in combination with a plurality of monomers. It is also possible to add other hydrophilic monomers having unsaturated double bonds, such as acrylamide, methacrylamide, or the like. 2-carboxyethyl acrylate, 2-carboxyethyl methacrylate, methyl acrylate, ethyl acrylate, dimethylamine propylene acrylamide, chlorinated propylene acrylamide trimethylammonium, but not added to destroy high water absorption The physical properties of the resin are the principle.

The concentration of the aqueous monomer solution is not particularly limited in carrying out the radical polymerization reaction, but the preferred concentration is preferably controlled to be between 20% by weight and 55% by weight, and the appropriate concentration is between 30% by weight and 45% by weight. When the concentration is less than 20% by weight, the hydrogel after polymerization is too soft and sticky, and the mechanical concentration is not more than 55 wt%, close to the saturation concentration, difficult to formulate and the reaction is too fast. The reaction heat is not easy to control, The pH of the saturated monomer aqueous solution is not less than 5.5. If it is less than 5.5, the residual monomer content in the hydrogel after polymerization is too high, resulting in poor physical properties of the superabsorbent resin.

In the aqueous monomer solution before the radical polymerization reaction, the addition of the coating-treated foaming agent to carry out the polymerization reaction in the reaction can increase the absorption speed of the superabsorbent resin, and the amount of the coated foaming agent added is It accounts for 0.01-10wt% of the water-soluble unsaturated monomer, and the additive amount is less than 0.01wt% by weight. The polymerization amount is more than 10wt% by weight, the polymerization reaction is too intense, and the hydrogel volume becomes larger after the polymerization reaction. , resulting in poor on-site operation.

After the carbonate compound is mixed with the alum compound, heat treatment is carried out in the range of 40 ° C to 95 ° C to allow the alum compound to be uniformly and rapidly coated with the carbonate compound to achieve the effect of the present invention. The heat treatment temperature is less than 40 ° C for too long, and it is not economical; if the heat treatment temperature is above 95 ° C, the coating effect is not good, and the heat treatment time is preferably from 3 minutes to 20 minutes. Heat treatment apparatuses suitable for use in the present invention include: tunnel type mixed dryers, drum dryers, table top dryers, fluidized bed dryers, air flow dryers, and infrared dryers.

In the aqueous monomer solution before the radical polymerization, a water-soluble polymer such as partially saponified or fully saponified polyvinyl alcohol, polyethylene glycol, polyacrylic acid may be added to reduce the cost. , polyacrylamide, starch or starch derivatives such as methyl cellulose, methyl cellulose acrylate, ethyl cellulose and other polymers, the molecular weight of such water-soluble polymers is not particularly limited, and its preferred water solubility The polymer may be starch, partially saponified or fully saponified polyvinyl alcohol, or the like, either alone or in combination. A suitable weight percentage of the superabsorbent resin containing such a water-soluble polymer is from 0 wt% to 20 wt%, preferably from 0 wt% to 10 wt%, more preferably from 0 wt% to 5 wt%, and when added more than 20 wt% Affecting physical properties, making physical properties worse.

The radical polymerization crosslinking agent is added to the unreacted monomer solution before the radical polymerization reaction, and the radical polymerization crosslinking agent may be a compound having two or more unsaturated double bonds, such as: N,N'-bis(2-propenyl)amine, N,N'-methine bis acrylamide, N,N'-methine bismethyl acrylamide, propylene acrylate, ethylene glycol Acrylate, polyethylene glycol diacrylate, ethylene glycol dimethacrylate, polyethylene glycol dimethacrylate, glycerin triacrylate, glycerol trimethacrylate, glycerin plus ethylene oxide Acrylate or trimethacrylate, trimethylolpropane plus ethylene oxide triacrylate or trimethacrylate, trimethylolpropane trimethacrylate, trimethylolpropane triacrylate, N, N, N- Tris(2-propenyl)amine, ethylene glycol diacrylate, polyoxyethylene glyceryl triacrylate, diethyl polyoxyethylene glyceryl triacrylate, dipropylene triethylene glycol ester, etc., may also have two or a compound of two or more epoxy groups, such as sorbitol polyglycidyl ether, polypropylene Polyglycidyl ether, ethylene glycol diglycidyl ether, diethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, diglycerol polyglycidyl ether, etc., after radical reaction The superabsorbent resin has an appropriate degree of crosslinking and appropriate processability.

The above-mentioned radical polymerization crosslinking agent may be used singly or in combination of two or more. The radical polymerization crosslinking agent is suitably added in an amount of from 0.001% by weight to 5% by weight based on the total solids of the reactants, more suitably in an amount of from 0.01% by weight to 3% by weight, based on the additive The amount of the hydrate after polymerization at a weight percentage of 0.001% by weight or less is too soft and viscous to be unfavorably mechanically processed, and the amount of the additive is too low at a weight percentage of 5 wt% or more to lower the resin property.

The carboxylic acid group of the acid group-containing monomer should be neutralized to control the pH of the finished product to make it neutral or slightly acidic. The neutralizing agent is a hydroxide or carbonate compound of the alkali or alkaline earth group of the periodic table. For example, sodium hydroxide, potassium hydroxide, sodium carbonate, potassium carbonate, sodium hydrogencarbonate, potassium hydrogencarbonate or an ammonia compound; the neutralizing agent may be used alone or in combination of two or more.

The carboxylic acid group of the acid group-containing monomer is neutralized to a sodium salt or a potassium salt or an ammonium salt, and the percentage of the molar ratio of the molar group is between 45 mol% and 85 mol%, preferably between 50 mol% and 75 mol%, and the neutralization is carried out. When the percentage of Mohr is 45mol% or less, the pH value of the finished product will be low. When the percentage of neutral concentration is 85mol% or more, the pH value of the finished product will be high. When the pH value of the finished product is not neutral or slightly acidic, if not Careful contact with the human body is not suitable and less safe.

The prepolymerization begins with the decomposition of the initiation (starting) agent to generate free radicals. The polymerization initiator may be selected from a thermal decomposition type initiator, and a suitable thermal decomposition type initiator is a peroxide such as hydrogen peroxide, di-tert-butyl peroxide, guanidinium peroxide or persulfate. (ammonium salt, alkali metal salt), and the like, and an azo compound such as: 2. 2'-azobis(2-amidinopropane) dihydrochloride, 2. 2'-azobis (N, N - bis-methylisobutyl hydrazine) dihydrochloride; a reducing agent may also be used to make it a redox-type initiator, such as an acid sulfite, thiosulfate, ascorbic acid or ferrous salt; or A redox type initiator and a thermal decomposition type initiator are used in combination.

First, the redox initiator is reacted first to generate a radical, and when the radical is transferred to the monomer, the polymerization is initiated. Since the polymerization reaction proceeds, a large amount of heat is released to raise the temperature, and when the decomposition temperature of the thermal decomposition type initiator is reached, the decomposition of the second thermal decomposition type initiator is caused, and the entire polymerization reaction is further caused. It’s complete.

A suitable amount of the radical polymerization initiator is generally from 0.001% by weight to 10% by weight based on the weight of the neutralized acrylate, and more suitably in an amount of from 0.1% by weight to 5% by weight, based on the weight. When the percentage is 0.001% by weight or less, the reaction is too slow to be economically advantageous; when the weight percentage is 10% by weight or more, the reaction is too fast, the reaction heat is not easily controlled, and the polymerization is excessively easy to form a gel-like solid.

The polymerization reaction of the present invention can be carried out in a conventional batch reaction vessel or on a conveyor belt reactor, and the gel obtained by the reaction is first cut into a small gel body having a diameter of 2.00 mm or less by a mincer, and the diameter is 10 mm. The following is better, and then 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 reactor for re-shearing. The gel body having a particle diameter of 0.03 mm or less is subjected to drying and pulverization treatment, and the amount of fine powder of the finished product is easily increased. When the gel body having a particle diameter of 2.00 mm or more is dried, it is easy to cause a defective product due to poor heat conduction effect. The disadvantage of high body and poor physical performance. According to the invention, the narrower the particle size distribution of the acrylate gel, the better, not only can the gel body be in an optimal state after drying, but also beneficial to control the drying time and temperature, and after the screening is completed. Drying.

The drying temperature is preferably dried at a temperature of 100 ° C to 180 ° C. The drying time is less than 100 ° C for a long time, and the drying time is not economical. The drying temperature is above 180 ° C to dry the crosslinker to crosslink the reaction early. In the subsequent drying process, since the degree of crosslinking is too high, the residual monomer cannot be effectively removed, and the effect of reducing the residual monomer is achieved.

After drying, the powder is pulverized, the fixed particle diameter is screened, and the surface crosslinking agent coating treatment is performed. The screening fixed particle size 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 improve the finished dust, and the particles having a particle diameter of 1.00 mm or more slow the water absorption rate of the finished product. According to the present invention, the particle size distribution of the acrylate polymer is as narrow as possible.

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, and the liquid permeability, etc. The surface is further bridged, and the surface cross-linking treatment utilizes a report having a polyfunctional crosslinking agent capable of reacting with an acid group, which 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) using an organic solution, water, ether compound (JP-A-2-153903), etc.; Increase the absorption rate and increase the water absorption rate under pressure, but also cause the retention force to drop too much. Adverse consequences, reduce the performance of the 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, etc.; A polyamine such as ethylenediamine, diethylenediamine or triethylenediamine is used; or a compound having two or more epoxy groups such as sorbitol polyglycidyl ether or polyglycerol polyglycidyl ether can be used. , ethylene glycol diglycidyl ether, diethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, diglycerol polyglycidyl ether, etc.; an alkylene carbonate such as ethylene glycol carbonate can also be used. Ester, 4-methyl-1,3-dioxol-2-one, 4,5-dimethyl-1,3-dioxol-2-one, 4,4-di Methyl-1,3-dioxol-2-one, 4-ethyl-1,3-dioxol-2-one, 1,3-dioxane-2 a ketone, 4,6-dimethyl-1,3-dioxan-2-one or 1,3-dioxepane-2-one.

The 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 10% by weight based on the total solids of the reactants, and more suitably in the amount of 0.005wt. Between % 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, and when the amount of the crosslinking agent additive is 10% by weight or more, the water absorption is too low, and the resin property is lowered.

The coating treatment of the surface crosslinking agent, the surface crosslinking agent is added according to the type of the surface crosslinking agent, directly added to the surface crosslinking agent, or adjusted to form a surface crosslinking agent aqueous solution, or adjusted to a surface crosslinking agent. The aqueous solution of the hydrophilic organic solvent is added, and the hydrophilic organic solvent such as methanol, ethanol, propanol, isobutanol, acetone, methyl ether, diethyl ether or the like is not particularly limited, and a solution can be formed, wherein methanol and ethanol are preferred (US Patent) No. 6849665).

The object of the present invention is to provide a superabsorbent resin which is powdery, insoluble in water, and capable of absorbing water or urine and blood. The resin has a fast absorption speed and has a high absorption rate characteristic at a relatively high pressure. . Its manufacturing methods include:

(a) using a water-soluble unsaturated monomer containing an acid group-containing monomer, wherein the ratio is in the range of 45 mol% to 85 mol%, and the concentration is in the range of 20 wt% to 55 wt%;

(b) adding a polymerization reaction via a coating treated blowing agent;

(c) the hydrogel obtained after the polymerization is sheared, granulated and dried, pulverized and sieved using a hot air at a temperature of from 100 ° C to 180 ° C;

(d) After the surface crosslinking agent is coated, the surface treatment is heated using a temperature of 80 ° C to 230 ° C.

The above technical feature is that when a polymerization reaction is carried out by using a coating-treated blowing agent and a water-soluble unsaturated monomer, the carbonate compound of the foaming agent is slowly released to make the surface of the super absorbent resin highly porous. Sexuality (please refer to Figure 1 and Figure 2) for the effect of fast absorption speed; the polyvalent metal ions in the alum compound also bond with the carboxylate in the superabsorbent resin to improve the high water absorption. The strength of the resin makes the super absorbent resin produced by the present invention have a characteristic of having a high absorption ratio at a high pressure.

For the purpose of the present invention, it is only necessary to add a coating-treated foaming agent in the polymerization reaction, that is, to produce a superabsorbent resin in a water-soluble unsaturated monomer aqueous solution. The rapid absorption rate and the superabsorbent resin which has a high absorption ratio under high pressure make the invention more applicable to various types of sanitary products, agricultural materials and water absorption agents for food preservation.

In order to show the water absorption capacity under pressure under the pressure of the super absorbent resin of the present invention, the present invention is determined by the retention force tea bag test method, and after taking the highest value and the lowest value after five measurement results, the average value is taken; 0.200±0.001 g is used. The super absorbent resin was placed in a tea bag and immersed in a 0.9% NaCl aqueous solution for 20 minutes, and then the soaked tea bag was placed in a centrifuge for centrifugation (diameter 23 cm, rotation speed 1400 rpm) for three minutes and then weighed. The obtained value is first obtained by subtracting the weight of the blank group tea bag which is not filled with the super absorbent resin (operating in the same step) and dividing by the weight of the polymer to obtain the retention value.

The water absorption capacity under pressure of the superabsorbent resin of the present invention is measured by a pressure absorption weight (pressure load: 20 g/cm ² (0.3 psi) and 49 g/cm ² (0.7 psi)), and the pressure absorption amount is based on The method described in the seventh page of the specification of European Patent No. 0339461A; placing a superabsorbent resin of a preliminary weight in a cylinder according to the bottom of the screen, and applying a pressure of 20 g/cm ² and 49 g/cm ² to the powder. Then, the cylinder is placed on an absorbent demand tester, and the superabsorbent resin absorbs 0.9% sodium chloride aqueous solution for one hour, measures the water absorption weight, and then divides the obtained value by the weight of the super absorbent resin, that is, The pressure is absorbed by the weight.

The Vortex Index (VI) of the present invention is carried out according to the method described below, and the average value and the lowest value are removed after five measurements, and the average value is obtained; 0.9% is added to the 100 mL beaker. 50 mL of an aqueous solution of sodium chloride, placed in an electromagnetic stir bar and placed in a magnetic stirrer at a speed of 600 rpm. The analytical balance was taken to 2.000 ± 0.001 g of superabsorbent resin, poured into a beaker and the code table was started. Record the time it takes for the vortex to disappear. The value obtained is divided by the weight of the actual superabsorbent resin to obtain a vortex disappearance index value.

The weight of the actual superabsorbent resin of the present invention is carried out according to the method described below: weighing 5.000 ± 0.001 g of superabsorbent resin (SAP) is placed in a glass plate of a thermoanalytical balance and the weight is set, and the analysis temperature is set to At 140 ° C, the analysis time is 15 minutes. After the analysis is completed, the water content of the super absorbent resin is obtained in units of percentage. The value obtained by multiplying the weight of the superabsorbent resin by the percentage of deduction is the weight of the actual superabsorbent resin.

The invention is illustrated by the following description and examples; however, the scope of the invention is not limited by the examples.

Reference example 1:

Take 200g of sodium carbonate (Taiwan Plastics Co., Ltd., product name: FP-100A) and 800g of ammonia alum (Taiwan Alum) for heat treatment at 50 °C for 15 minutes. After cooling, the treated foaming agent is applied. A).

Reference example 2:

800 g of calcium carbonate (Taiwan Plastics Co., Ltd., product name: FP-100A) and 200 g of potassium alum (Taiwan Minghao Company) were heat-treated at 80 ° C for 25 minutes. After cooling, the treated foaming agent was applied. B).

Reference example three:

Take 500g of sodium bicarbonate (China Red Triangle Company, product name: AK-28) and 500g of potassium alum (Taiwan Alum) for heat treatment at 60 ° C for 30 minutes, after cooling, the coated foam Agent (C).

Embodiment 1:

1) Take 218.7 g of 48% sodium hydroxide aqueous solution and slowly add 270 g of acrylic acid and 291.6 g of water in a 3000 c.c conical flask. The dropping ratio of sodium hydroxide/acrylic acid is in the range of 0.85 to 0.95, and the dropping time is 2 hours. And maintaining the temperature of the neutralization reaction system in the bottle in the range of 20 ° C to 40 ° C; at this time, a monomer concentration of 42 wt% aqueous solution was obtained, in which 70 mol% (mole ratio) of the acrylic acid portion was neutralized to sodium acrylate.

2) 0.414 g of N,N'-methinebisacrylamide and 0.781 g of a foaming agent (A) were added to the water-soluble unsaturated monomer solution, and the temperature was maintained at about 20 °C.

3) Add 0.144 g of hydrogen peroxide, 1.8 g of sodium hydrogen sulfite and 1.8 g of ammonium persulfate initiator.

4) The gel formed after the reaction was chopped by a cutter mill, and a gel having a particle size of 2 mm or less was selected.

5) Drying at 130 ° C for 2 hours; using a 0.1 mm to 0.85 mm fixed particle size sieve to obtain a powdery superabsorbent resin.

6) Take 100 g of the powdery superabsorbent resin obtained in the above 5), and add 2.5 g of ethylene glycol, 1,4-butanediol (manufactured by Taiwan Plastics Co., Ltd.) and methanol 1/1/0.5 mixed solution to 150 ° C. The temperature was heat-treated for 1 hour, and after cooling, a high-performance superabsorbent resin was obtained. The measurement retention was 32.7 g/g, the water absorption ratio at a pressure of 20 g/cm ² was 29.6 g/g, the water absorption ratio under a pressure of 49 g/cm ² was 19.4 g/g, the water content was 0.92%, and the VI value was 28.56 sec/g.

Embodiment 2:

Example 1 was repeated, but the amount of the foaming agent (A) added was increased to 11.72 g. The same as the first example, a high performance superabsorbent resin was obtained, and the retention was 31.5 g/g, the water absorption ratio was 30.2 g/g under a pressure of 20 g/cm ² , and the water absorption ratio was 19.7 g/g under a pressure of 49 g/cm ² . It is 1.12% and the VI value is 20.75 sec/g.

Embodiment 3:

Example 1 was repeated except that the blowing agent (B) was used instead of the blowing agent (A). Examples of a same rest, to obtain a high-performance water-absorbent resin, measuring the holding power of 30.9g / g, water absorption ratio 18.7g / g, water content of water absorption capacity under a ^pressure under a ^pressure of 20g / cm 29.4g / g, 49g / cm It was 1.23% and the VI value was 21.47 sec/g.

Embodiment 4:

Example 3 was repeated, but the amount of the blowing agent (B) added was increased to 3.91 g. With the remaining three examples, high-performance water-absorbing resin can be obtained, measuring the holding power was 31.5g / g, water absorption ratio of water absorption capacity under a ^pressure of 29.1g / g, 49g / cm 18.7g / g, under a ^pressure of an aqueous 20g / cm The rate was 1.08% and the VI value was 20.02 sec/g.

Embodiment 5:

Example 1 was repeated except that a blowing agent (C) was used instead of the blowing agent (A). Examples of a same rest, to obtain a high-performance water-absorbent resin, measuring the holding power of 31.2g / g, water absorption ratio 19.1g / g, water content of water absorption capacity under a ^pressure under a ^pressure of 20g / cm 28.9g / g, 49g / cm It is 1.14% and the VI value is 25.71 sec/g.

Example 6:

By repeating Example 1, 0.391 g of a foaming agent (C) and 0.391 g of a foaming agent (A) were used at the same time. In the same manner as in the first embodiment, a high-performance superabsorbent resin was obtained, and the water absorption ratio was 29.2 g/g under a pressure of 20 g/cm ² and the water absorption ratio at a pressure of 49 g/cm ² was 18.9 g/g, and the water content was 1.12. %, the VI value is 26.45 sec/g.

Example 7:

1) Take 218.7 g of 48% sodium hydroxide aqueous solution and slowly add 270 g of acrylic acid and 291.6 g of water in a 3000 c.c conical flask. The dropping ratio of sodium hydroxide/acrylic acid is in the range of 0.85 to 0.95, and the dropping time is 2 hours. And maintaining the temperature of the neutralization reaction system in the bottle in the range of 20 ° C to 40 ° C; at this time, a monomer concentration of 42 parts by weight of an aqueous solution in which 70 mol % (mole ratio) of the acrylic acid portion was neutralized to sodium acrylate was obtained.

2) 0.414 g of N,N'-methine bis acrylamide and 0.781 g of a foaming agent (C) were added to the water-soluble unsaturated monomer solution, and the temperature was maintained at about 20 °C.

3) Add 0.144 g of hydrogen peroxide, 1.8 g of sodium hydrogen sulfite and 1.8 g of ammonium persulfate initiator.

4) The gel formed after the reaction was chopped by a cutter mill, and a gel having a particle size of 2 mm or less was selected.

5) Drying at 130 ° C for 2 hours; using a 0.1 mm to 0.85 mm fixed particle size sieve to obtain a powdery superabsorbent resin.

6) 100 g of superabsorbent resin, 2.5 g of ethylene glycol, 1,4-butanediol (manufactured by Taiwan Plastics Co., Ltd.) and 1/1/0.5 mixed methanol solution, and heat-treated at 150 ° C for 1 hour. 10g of this superabsorbent resin was weighed and 0.1g of cerium oxide powder was added. After mixing evenly, 1.2 g of polyethyleneimine:water=1:3 (weight ratio) solution was added to carry out anti-caking treatment. High performance super absorbent resin. The measurement retention was 31.5 g/g, the water absorption ratio under a pressure of 20 g/cm ² was 28.4 g/g, the water absorption ratio under a pressure of 49 g/cm ² was 19.1 g/g, the water content was 2.13%, and the VI value was 24.37 sec/g.

Example 8:

Example 7 was repeated except that a blowing agent (B) was used instead of the blowing agent (C). Examples of a same rest, to obtain a high-performance water-absorbent resin, measuring the holding power of 30.9g / g, water absorption ratio 19.3g / g, water content of water absorption capacity under a ^pressure under a ^pressure of 20g / cm 29.4g / g, 49g / cm It was 2.31% and the VI value was 23.98 sec/g.

Comparative example 1:

Repeating Example 1, 1.4 g of calcium carbonate (Taiwan Plastics Co., Ltd., product name: FP-100A) was used. In the same manner as in the first embodiment, a high-performance superabsorbent resin was obtained, and the retention was 32.2 g/g, the water absorption ratio under pressure of 20 g/cm ² was 28.7 g/g, and the water absorption ratio under pressure of 49 g/cm ² was 17.4 g/g. The rate was 1.01% and the VI value was 42.71 sec/g.

Comparative example 2:

Repeat the comparison example 1, but replace the calcium carbonate with sodium bicarbonate (China Red Triangle Company, product name: AK-28). Comparative Example a, to obtain a high-performance water-absorbent resin was measured with the remaining holding force of 32.8g / g, water absorption ratio of water absorption capacity under a ^pressure of 28.4g / g, 49g / cm 17.1g under a ^pressure of 20g / cm / g, the aqueous The rate was 1.03% and the VI value was 43.55 sec/g.

Comparative example three:

Comparative Example 2 was repeated, but the amount of sodium hydrogencarbonate added was 2.8 g. Comparative Example with the remaining two to obtain high-performance water-absorbent resin, measuring the holding power of 32.5g / g, water absorption ratio of water absorption capacity under a ^pressure of 25.6g / g, 49g / cm 10.7g under a ^pressure of 20g / cm / g, the aqueous The rate was 1.17% and the VI value was 40.21 sec/g.

Comparative Example 4:

Repeat Comparative Example 2, but potassium alum (Taiwan Alum) replaces calcium carbonate. Comparative Example with the remaining two to obtain high-performance water-absorbent resin, measuring the holding power of 28.7g / g, water absorption ratio of water absorption capacity under a ^pressure of 29.4g / g, 49g / cm 19.8g under a ^pressure of 20g / cm / g, the aqueous The rate was 1.26% and the VI value was 51.72 sec/g.

Comparative Example 5:

Repeat Comparative Example 2, but replace the calcium carbonate with calcined kaolin (China Guangying Company, product name: GF-60). Comparative Example with the remaining two to obtain high-performance water-absorbent resin, measuring the holding power of 29.1g / g, water absorption ratio of water absorption capacity under a ^pressure of 27.6g / g, 49g / cm 16.2g under a ^pressure of 20g / cm / g, the aqueous The rate was 1.13% and the VI value was 49.37 sec/g.

Fig. 1 is a view showing an SEM (scanning electron microscope) photograph of the high-performance superabsorbent resin particles obtained in Example 1.

Fig. 2 is a view showing an SEM (scanning electron microscope) photograph of the high-performance superabsorbent resin particles obtained in Comparative Example 1.

Claims (7)

A method for producing a super absorbent resin, comprising: (a) a water-soluble unsaturated monomer having an acid group-containing monomer, wherein a neutralization ratio is in the range of 45 mol% to 85 mol%, and a concentration is 20 wt% to 55 wt% a range of aqueous solutions; (b) adding 0.01% by weight to 10% by weight of the total amount of the resin, a polymerization reaction is carried out via a mixture of a coated carbonate compound and an alum compound; (c) a polymerization reaction The hydrogel body is sheared, granulated and dried by hot air at a temperature of 100 ° C to 180 ° C, pulverized, and screened; (d) after being coated with a surface crosslinking agent in an amount of 0.005 wt% to 5 wt% of the total amount of the resin, The surface treatment is heated using a temperature of 80 ° C to 230 ° C. The method for producing a super absorbent resin according to claim 1, wherein the carbonate compound has a carbonate or a hydrogencarbonate compound in a chemical structure. The method for producing a super absorbent resin according to claim 1, wherein the alum compound is potassium alum, sodium alum or ammine which contains water of crystallization. The method for producing a super absorbent resin according to claim 1, wherein a mixing ratio of the carbonate compound to the alum compound is from 5:95 to 95:5. The method for producing a super absorbent resin according to claim 1, wherein the treatment temperature during the coating treatment is from 40 ° C to 95 ° C. The method for producing a super absorbent resin according to claim 1, wherein the superabsorbent resin produced has a vortex disappearance index (VI value) of not more than 35 sec/g. The method for producing a super absorbent resin according to claim 1, wherein the superabsorbent resin produced has a holding power of not less than 20 g/g, and the water absorption ratio under a pressure of 49 g/cm ^{2 is} not less than 12 g/g. .