CN102311557B - Manufacturing method of superabsorbent resin - Google Patents

Abstract

A simple method for producing a super absorbent resin, which has a rapid absorption rate by adding a foaming agent.

Description

Manufacturing method of superabsorbent resin

technical field

The invention relates to a production method of superabsorbent resin.

Background technique

Superabsorbent resins are widely used in water retaining agents in agriculture or gardening, anti-dew condensation agents in building materials and materials for removing moisture from petroleum, or outer waterproof coating agents in cables and sanitary products, Such as diapers, feminine hygiene products, disposable wipes, etc., especially for diapers.

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

When the superabsorbent resin or pulp fiber in the absorbent layer absorbs liquid, it will rapidly expand to cause the void space in the superabsorbent resin and pulp fiber or the pores in the superabsorbent resin to be closed, thereby inhibiting the flow of liquid. This phenomenon is called Gel-blocking (Gel-blocking); once this phenomenon occurs, the subsequent liquid can no longer penetrate the absorber, and it will flow to the absorber. edge flow, resulting in leakage.

In addition, colloidal clogging occurs in the superabsorbent resin near the swelling area, and the rest of the liquid cannot reach the deeper part, 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 blocking is to change the absorption rate of superabsorbent resin (U.S. Patent No. 4,548,847). Water-soluble compounds such as disodium diaminetetraacetic acid or ammonium hydrogen phosphate, and hydrogels formed by at least one divalent metal ion, use the method of reducing the cross-linking density in the hydrogel to make high water absorption Resin absorbs liquid more easily.

EP 0 631 768 A1 mentions an absorber which utilizes superabsorbent resins with different particle size distributions (type 1 in the range of 600-850um and type 2 in the range of less than 250um) to further produce Absorbents with different absorption rates, however, the differences in absorption rates are not large.

U.S. Patent No. 5,115,011 mentioned that the use of sulfate, acetate or nitrate compounds with aluminum, calcium, magnesium, and monovalent metal salts or ammonium salt compounds of sulfurous acid, mixed with less than 10 parts by weight, can reduce colloidal blocking occurrence of the phenomenon.

The above-mentioned U.S. Patent No. 5,115,011 also mentions an absorbent for absorbing blood and liquids, which uses a mixture of a superabsorbent resin and a halogen compound with a phosphoric acid group, a sulfite group or a sulfate group. This type of mixture is called The water-soluble mixture (stored at room temperature in the state of flowing powder, which is harmless to organisms) is dissolved in unsaturated monomers for polymerization, so that the diffusion speed of the liquid can be improved.

In addition, the use of water-soluble anionic compounds with carboxylic acid groups, sulfonic acid groups, and phosphoric acid groups and polyvalent metals with a valence of at least 3, such as antimony (Antimony), can also reduce the colloidal blocking phenomenon. occurs (US Patent No. 5,578,318).

Furthermore, the use of citrate or sulfate polyvalent metal salt solution mixed with superabsorbent resin can produce superabsorbent resin with low absorption rate, but it must be obtained through secondary processing, resulting in a significant reduction in production. Efficiency (US Patent Nos. 6,433,058, 6,579,958).

Use polyol compound and carbonate compound in fluid-bed spray granulator dryer (Fluid-bed spray granulator dryer) to mix and granulate, and then add unsaturated monomer to carry out polymerization reaction, although this can improve the absorption speed of liquid, However, the polyol compound is used for coating, that is, the superabsorbent resin produced by this method is prone to yellowing (Yellow-coloring change), and it must be mixed for about 60 to 120 minutes by a fluidized bed spray granulation dryer can be obtained, resulting in a significant reduction in production efficiency (US Patent No. 7,163,966).

The problem to be solved by the present invention is that ultra-thin diapers must have a high-density absorbing layer, especially for absorbers with multiple absorbing layers, preventing colloid blocking is a very important issue. One of the methods to solve this problem is to use a superabsorbent resin with a slow penetration rate or a fast absorption rate in the absorbent body. However, the above-mentioned methods cannot produce a satisfactory superabsorbent resin.

Contents of the invention

The object of the present invention is to provide a manufacturing method of superabsorbent resin to overcome the defects in the known technology.

In order to achieve the above object, the manufacturing method of the superabsorbent resin provided by the present invention includes:

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

(b) Adding 0.01wt% to 10wt% of the total amount of the resin to carry out the polymerization reaction through the foaming agent treated by coating;

(c) The hydrogel obtained after the polymerization reaction is sheared, granulated, dried, pulverized, and screened with hot air at a temperature of 100°C to 180°C;

(d) After being coated with a surface cross-linking agent accounting for 0.005wt%-5wt% of the total resin, the surface is treated by heating at a temperature of 80°C to 230°C.

In the method for producing superabsorbent resin, the coated foaming agent is a mixture of carbonate compounds and alum compounds.

In the method for producing a superabsorbent resin, the carbonate compound is a compound having carbonate or bicarbonate in its chemical structure.

The method for producing a superabsorbent resin, wherein the alum compound is potassium alum, sodium alum or ammonia alum containing crystal water.

In the method for producing superabsorbent resin, the weight mixing ratio of the carbonate compound and the alum compound is 5:95 to 95:5.

In the manufacturing method of the superabsorbent resin, the treatment temperature during the coating treatment is 40°C to 95°C.

In the method for producing superabsorbent resin, the vortex extinction index (VI value) of the produced superabsorbent resin is not greater than 35 sec/g.

The manufacturing method of the superabsorbent resin, wherein the retention force of the produced superabsorbent resin is not lower than 20g/g, and the water absorption capacity under the pressure of 49g/cm ² is not lower than 12g/g.

The invention provides a powdery, water-insoluble, superabsorbent resin capable of absorbing water, urine and blood. The resin has a fast absorption rate and has a high absorption rate under relatively high pressure.

Description of drawings

FIG. 1 is a diagram obtained by taking a SEM (scanning electron microscope) photograph of the high-performance superabsorbent resin particles obtained in Example 1. FIG.

FIG. 2 is a diagram obtained by taking a SEM (scanning electron microscope) photograph of the high-performance superabsorbent resin particles obtained in Comparative Example 1. FIG.

Detailed ways

The present invention provides a superabsorbent resin with fast absorption rate and high absorption rate under high pressure. Furthermore, the superabsorbent resin produced by the present invention has a rapid absorption rate for liquids, 0.9 The vortex disappearance index of % sodium chloride aqueous solution is not more than 35sec/g, and the water absorption capacity under the pressure of 49g/ ^cm2 is not less than 12g/g.

According to the present invention, the present invention prepares a kind of manufacturing method of superabsorbent resin with fast absorbing speed at least comprising:

(1) In the aqueous solution of acid group-containing monomers with a neutralization rate of 45 mole percent or more, the acid group-containing monomers are selected from acrylic acid or methacrylic acid or 2-propenylamine-2-methylpropanesulfonic acid or the above groups mixture;

(2) Adding the foaming agent treated by coating and the polymerization initiator to carry out free radical polymerization to generate superabsorbent resin gel;

(3) shearing the hydrogel into small hydrogels;

(4) The gel is then dried, crushed and screened with hot air at a temperature of 100°C to 250°C;

(5) Finally, a surface crosslinking reaction is performed on the surface of the superabsorbent resin.

The above method for producing a superabsorbent resin having the characteristics of fast absorption speed and high absorption rate under high pressure, wherein the coating-treated foaming agent added for polymerization reaction is a carbonate compound, And a mixture of alum compounds, the mixing ratio of the carbonate compound and alum compound is 5:95 to 95:5, the carbonate compound is a compound with carbonate or bicarbonate in the chemical structure, such as: sodium carbonate, Potassium carbonate, ammonium carbonate, magnesium carbonate, calcium carbonate, barium carbonate, sodium bicarbonate, potassium bicarbonate, ammonium bicarbonate, magnesium bicarbonate, calcium bicarbonate or barium bicarbonate, etc. Alum compounds are compounds containing crystal water, such as potassium alum, sodium alum or ammonia alum.

It is generally known that the water-soluble unsaturated monomers used in the manufacture of water-absorbent resins, in addition to acrylic acid, can also use other water-soluble monomers with acidic groups and unsaturated double bonds, such as: methacrylic acid, maleic acid, fumaric acid , 2-propenylamine-2-methylpropanesulfonic acid, maleic acid, maleic anhydride, fumaric acid, fumaric anhydride, etc. There are no specific restrictions on the selection of monomers. Only one type can be used, and multiple monomers can also be used together. Other hydrophilic monomers with unsaturated double bonds can also be added according to the situation, such as: acrylamide, methacryl Amide, 2-carboxyethyl acrylate, 2-carboxyethyl methacrylate, methyl acrylate, ethyl acrylate, dimethylamine acrylamide, acrylamide trimethylammonium chloride, but the amount added is not to damage the super absorbent The physical properties of the permanent resin are the principle.

During free radical polymerization, the concentration of the monomer aqueous solution is not particularly limited, but the preferred concentration should be controlled between 20wt% and 55wt%, and the appropriate concentration is between 30wt% and 45wt%. When the concentration is below 20wt%, the polymerized hydrogel is too soft and viscous, which is unfavorable for mechanical processing. The added concentration is above 55wt%, which is close to the saturation concentration, and it is difficult to prepare and the reaction is too fast. The pH value of the saturated monomer aqueous solution is not lower than 5.5. If it is lower 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 monomer aqueous solution before the radical polymerization reaction, adding the foaming agent that has been coated and treated to carry out the polymerization reaction in this reaction can increase the absorption speed of the super absorbent resin. The amount of the foaming agent that has been coated and treated is Accounting for 0.01-10wt% of the water-soluble unsaturated monomer, the additive amount has no effect below 0.01wt% by weight, and the polymerization reaction is too violent if the additive amount is above 10wt%, and the volume of the hydrogel becomes larger after the polymerization reaction , resulting in poor field operability.

When the carbonate compound weight ratio of the whipping agent that has been processed is lower than 5%, can't reach the expected effect of the present invention, when higher than 96%, then because the amount of alum compounds is too low, can't effectively coat carbonate Compound, make carbonate compound contact with unsaturated monomer aqueous solution immediately and form carbon dioxide gas escape, also can't reach the expected effect of the present invention. The suitable weight mixing ratio of carbonate compound and alum compound is 5:95 to 95:5, preferably 20:80 to 80:20.

After the carbonate compound and the alum compound are mixed, heat treatment is carried out at a temperature ranging from 40°C to 95°C, so that the alum compound can be coated with the carbonate compound uniformly and rapidly to achieve the effect of the present invention. If the heat treatment temperature is below 40°C, the coating time will be too long, which is not economical; if the heat treatment temperature is above 95°C, the coating effect will be poor and the quality will be affected. The heat treatment time is preferably 3 minutes to 20 minutes. Heat treatment devices suitable for the present invention include: tunnel-type mixing dryer, drum-type dryer, bench-type dryer, fluidized-bed dryer, air-flow dryer, infrared dryer, and the like.

In the aqueous monomer solution before free radical polymerization, water-soluble polymers can also be added to reduce costs, such as: partially saponified or fully saponified polyvinyl alcohol, polyethylene glycol, polyacrylic acid , polyacrylamide, starch or starch derivatives such as methyl cellulose, methyl cellulose acrylate, ethyl cellulose and other polymers, the molecular weight of these water-soluble polymers is not particularly limited, and its preferred water-soluble high The molecules are starch, partially saponified or fully saponified polyvinyl alcohol, etc., which can be used alone or in combination. The appropriate weight percentage of these water-soluble polymers added to the superabsorbent resin is 0wt% to 20wt%, but 0wt% to 10wt% is better, and 0wt% to 5wt% is especially preferred. Adding more than 20wt% will affect the physical properties. Make physical properties worse.

Add a free radical polymerization crosslinking agent to the unreacted monomer solution before the free radical polymerization. The free radical polymerization crosslinking agent can be a compound with two or more unsaturated double bonds, such as: N,N'-Bis(2-propenyl)amine, N,N'-Methylenebisacrylamide, N,N'-Methylenebismethacrylamide, Propylene Acrylate, Ethylene Glycol Diacrylate , Polyethylene glycol diacrylate, Ethylene glycol dimethacrylate, Polyethylene glycol dimethacrylate, Glycerin triacrylate, Glycerin trimethacrylate, Glycerin triacrylate with ethylene oxide added Or trimethacrylate, trimethylolpropane triacrylate or trimethacrylate with added ethylene oxide, trimethylolpropane trimethacrylate, trimethylolpropane triacrylate, N, N, N-tri( Two or two Compounds of the above epoxy groups, such as sorbitol polyglycidyl ether, polyglycerol polyglycidyl ether, ethylene glycol diglycidyl ether, diethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, bis Glycerol polyglycidyl ether, etc., can make superabsorbent resin have appropriate degree of crosslinking and processability after free radical reaction.

The above radical polymerization crosslinking agents may be used alone or in combination of two or more. The appropriate additive amount of free radical polymerization crosslinking agent is between 0.001wt% and 5wt% by weight (based on the total solid content of the reactant), and the more appropriate amount is between 0.01wt% and 3wt%. When the amount is less than 0.001 wt%, the hydrated body after polymerization is too soft and viscous to be unfavorable for mechanical processing, and when the additive amount is more than 5 wt%, the water absorption is too low, which reduces the performance of the resin.

The carboxylic acid group part of the acid group-containing monomer should be neutralized to control the pH value of the finished product, making it neutral or slightly acidic. The neutralizer is the hydroxide or carbonate of the alkali metal group or alkaline earth group of the periodic table , such as: sodium hydroxide, potassium hydroxide, sodium carbonate, potassium carbonate, sodium bicarbonate, potassium bicarbonate or ammonia compounds; this neutralizer can be used alone or in combination.

The carboxylic acid groups of the monomers containing acid groups are partially neutralized into sodium salts, potassium salts or ammonium salts, and the molar percentage of the neutralization rate is between 45mol% and 85mol%, preferably between 50mol% and 75mol%, and the neutralization rate When the molar percentage is less than 45mol%, the pH value of the finished product will be low, and when the molar percentage of neutralization concentration is above 85mol%, the pH value of the finished product will be high. Both are less suitable and less safe to touch.

Prepolymerization starts with the decomposition of a polymerization initiator (initiator) to generate free radicals. Polymerization initiator can be selected thermal decomposition type initiator, and suitable thermal decomposition type initiator has peroxide, as: hydrogen peroxide, two-tertiary butyl peroxide, peroxide amide or persulfate ( Ammonium salts, alkali metal salts), etc., and azo compounds such as: 2.2'-Azobis(2-amidinopropane) dihydrochloride, 2.2'-Azobis(N,N-Diethylene isobutylamidine) dihydrochloride; reducing agents can also be used to make it a redox initiator, such as: acid sulfite, thiosulfate, ascorbic acid or ferrous salt; or redox initiator Agents and pyrolytic initiators are used in combination.

First, the oxidation-reduction initiator is first reacted to generate free radicals, and when the free radicals are transferred to the monomer, the polymerization reaction is initiated. Since the polymerization reaction will release a large amount of heat to increase the temperature, when it reaches the decomposition temperature of the thermal decomposition type initiator, it will trigger the decomposition of the second thermal decomposition type initiator, and the whole polymerization reaction will be more rapid. to perfection.

Generally, the appropriate amount of free radical polymerization initiator is 0.001wt% to 10wt% by weight (based on the weight of neutralized acrylate), and the more appropriate amount is between 0.1wt% and 5wt% by weight. When the percentage is less than 0.001wt%, the reaction is too slow, which is unfavorable to economic benefits; when the weight percentage is more than 10wt%, the reaction is too fast, the heat of reaction is difficult to control, and it is easy to overpolymerize to form a gel-like solid.

The polymerization reaction of the present invention can be carried out in a traditional batch reaction vessel or on a conveyor belt reactor. The gel obtained by the reaction is first cut into small gels with a diameter of 2.00mm or less with a diameter of 10mm by a grinder. The following is better, and then filter.

The diameter of the gel with a fixed particle size screened is preferably less than 2.00mm, preferably between 0.05mm and 1.50mm, and the gel with a particle size larger than 2.00mm is sent back to the reactor for re-shredding. Drying and pulverizing the gel with a particle size of less than 0.03mm is likely to increase the amount of fine powder in the finished product. When drying the gel with a particle size of 2.00mm or more, it is easy to cause the finished product to be in the residual sheet due to poor heat conduction effect. The disadvantages of high body and poor performance of physical properties. According to the present invention, the narrower the particle size distribution of the acrylate gel, the better. Not only can the physical properties of the gel reach the best state after drying, but it is also beneficial to control the drying time and temperature. to dry.

The drying temperature should be between 100°C and 180°C. If the drying temperature is below 100°C, the drying time will be too long, which is not economical. If the drying temperature is above 180°C, the crosslinking agent will undergo crosslinking reaction earlier. In the subsequent drying process, the residual monomers cannot be effectively removed due to too high cross-linking, so as to achieve the effect of reducing the residual monomers.

After drying, it is crushed, screened to fix the particle size, and then coated with a surface cross-linking agent. Screening and fixed particle size is preferably between 0.06mm and 1.00mm, preferably between 0.10mm and 0.850mm. Fine powder with a particle size below 0.06mm will increase the dust of the finished product, and particles with a particle size above 1.00mm will slow down the water absorption rate of the finished product. According to the invention, the particle size distribution of the acrylate polymer should be as narrow as possible.

Superabsorbent resin is an insoluble hydrophilic polymer. The resin has a uniform bridging structure inside. Generally, in order to improve the quality, such as: increase the absorption rate, increase the colloid strength, improve the anti-caking property, liquid permeability, etc. Further bridging is carried out on the surface of the resin. This surface crosslinking treatment uses the report of a multifunctional crosslinking agent capable of reacting with acid groups. There have been many patent disclosures before the present invention; such as: dispersion of high water absorption Resin and crosslinking agent carry out surface crosslinking treatment in organic solvent (JP-A-56-131608, JP-A-57-44627, JP-A-58-42602, JP-A58-117222), use inorganic powder directly Mix the cross-linking agent and the cross-linking agent solution into the superabsorbent resin for treatment (JP-A60-163956, JP-A-60-255814), add the cross-linking agent and then treat it with steam (JP-A-1-113406), use Organic solvent, water and polyalcohol carry out surface treatment (JP-A-1-292004, U.S. Patent No. 6346569) use organic solution, water, ether (ether) compound (JP-A-2-153903) etc.; Although the method can increase the absorption rate and the water absorption rate under pressure, it also causes the adverse consequences of excessive reduction in the retention force and reduces the performance of practical applications.

According to the present invention, the cross-linking agent that can react simultaneously during surface treatment is polyalcohol such as: glycerol, ethylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol, propylene glycol etc.; Use polyamines such as: ethylenediamine, diethylenediamine, triethylenediamine; or compounds with two or more epoxy groups such as: sorbitol polyglycidyl ether, polyglycerol polyglycidyl ether , ethylene glycol diglycidyl ether, diethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, diglycerol polyglycidyl ether, etc.; also can use alkylene carbonate such as: ethylene glycol carbonate Esters, 4-methyl-1,3-dioxolan-2-one, 4,5-dimethyl-1,3-dioxolan-2-one, 4,4-di Methyl-1,3-dioxolane-2-one, 4-ethyl-1,3-dioxolane-2-one, 1,3-dioxolane-2 -ketone, 4,6-dimethyl-1,3-dioxan-2-one or 1,3-dioxepan-2-one, etc.

The usage of cross-linking agent can be used alone or in combination of two or more, and its appropriate additive amount is between 0.001wt% and 10wt% by weight (based on the total solid content of the reactant), and the more appropriate amount is 0.005wt% Between 5wt% and 0.001wt% of the crosslinking agent additive, the effect cannot be shown, and when the crosslinking agent additive is above 10wt%, the water absorption is too low and the performance of the resin is reduced.

Surface cross-linking agent coating treatment, the addition method of the surface cross-linking agent is divided into surface cross-linking agent added directly according to the type of surface cross-linking agent, or added as a surface cross-linking agent aqueous solution, or adjusted as a surface cross-linking agent Hydrophilic organic solvent aqueous solution is added, and hydrophilic organic solvents such as methanol, ethanol, propanol, isobutanol, acetone, methyl ether, ether, etc. are not particularly limited, they can form a solution, and methanol and ethanol are preferred ( U.S. Patent No. 6,849,665).

The invention provides a powdery, water-insoluble, superabsorbent resin capable of absorbing water, urine and blood. The resin has a fast absorption rate and has a high absorption rate under relatively high pressure. Its manufacturing methods include:

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

(b) adding the blowing agent processed through coating to carry out polymerization reaction;

(c) The hydrogel obtained after the polymerization reaction is sheared, granulated, dried, pulverized, and screened with hot air at a temperature of 100°C to 180°C;

(d) After the surface cross-linking agent is coated, the surface is treated by heating at a temperature of 80°C to 230°C.

The above-mentioned technical feature is that when the foaming agent treated by coating is used for polymerization reaction with water-soluble unsaturated monomer, the carbonate compound of the foaming agent will be released slowly so that the surface of the superabsorbent resin has a high degree of The effect of porosity (please refer to Figure 1 and Figure 2) can achieve the effect of rapid absorption rate; the multivalent metal ions in the alum compound also bond with the carboxylate in the superabsorbent resin to improve the absorption rate of the superabsorbent resin. The strength makes the superabsorbent resin produced by the present invention have the characteristics of high absorption rate under high pressure.

As far as the present invention is concerned, it is only necessary to add the coated blowing agent to the polymerization reaction during the polymerization reaction, that is, to produce a superabsorbent resin with an aqueous solution of water-soluble unsaturated monomers. The rapid absorption rate and the high water-absorbent resin with high absorption rate under high pressure make the present invention more suitable for various types of hygienic products, agricultural and food fresh-keeping water-absorbing agents.

In order to show the water absorption ratio under pressure of the superabsorbent resin of the present invention, the present invention uses the holding force tea bag test method to measure, and after removing the highest value and the lowest value from the measurement results for five times, take the average value; 0.200±0.001g The superabsorbent resin was packed in a tea bag and soaked in 0.9% NaCl aqueous solution for 20 minutes, then the soaked tea bag was placed in a centrifuge (diameter 23 cm, rotating speed 1400 rpm) for three minutes and then weighed. The obtained value first subtracts the weight of the tea bag of the blank group not filled with superabsorbent resin (operate in the same procedure) and then divides it by the weight of the polymer to obtain the holding force value.

The water absorption capacity under pressure of the superabsorbent resin of the present invention is measured using the pressure absorption weight (pressure load: 20g/cm ² (0.3psi) and 49g/cm ² (0.7psi)), and the pressure absorption is based on The method described on page 7 of European Patent No. 0339461A specification; put the initially weighed superabsorbent resin in a cylinder with sieve shading, and add 20g/ ^cm2 and 49g/ ^cm2 to the powder pressure, then place the cylinder on the absorbency demand tester, let the superabsorbent resin absorb 0.9% sodium chloride aqueous solution for one hour, measure the water absorption weight, and then divide the obtained value by the weight of the superabsorbent resin, That is, the value of the absorption weight under pressure is obtained.

Vortex Index of the present invention (Vortex Index, VI) is to carry out according to the method described below, and with five measurement results, after removing the highest value and the lowest value, take the average value; Add 0.9% chlorine in the beaker of 100mL Put 50mL of sodium chloride aqueous solution into an electromagnetic stirring rod and place the beaker in an electromagnetic stirrer at a speed of 600rpm. Use an analytical balance to take 2.000±0.001 grams of superabsorbent resin, pour it into the beaker and start a stopwatch to record the time when the vortex disappears. It takes time. The value obtained was divided by the weight of the actual superabsorbent resin to obtain the value of the swirl disappearing index.

The weight of the actual superabsorbent resin of the present invention is carried out according to the method described below: weigh 5.000 ± 0.001 gram of superabsorbent resin (SAP) and place it in a thermal analysis balance glass dish and record the weight, set the analysis temperature The temperature is 140°C, and the analysis time is 15 minutes. After the analysis is completed, the moisture content of the superabsorbent resin is obtained, and the unit is percentage. The value obtained by multiplying the weight of the superabsorbent resin by the deducted percentage is the actual weight of the superabsorbent resin.

The present invention is illustrated below with the best reference and examples; however, the scope of rights of the application of the present invention is not limited by these examples.

Reference example one

Get the sodium carbonate of 200g (Taiwan Plastics Company, product name: FP-100A) and the ammonia alum of 800g (Taiwan Alum Company) with 50 ℃ of temperature heat treatment 15 minutes, after cooling, obtain the foaming agent ( A).

Reference example two

Get the calcium carbonate of 800g (Taiwan Plastics Company, product name: FP-100A) and the potassium alum (Taiwan Alum Company) of 200g with 80 ℃ of temperature heat treatment 25 minutes, after cooling, obtain the foaming agent ( B).

Reference example three

Get 500g of sodium bicarbonate (China Red Triangle Company, product name: AK-28) and 500g of potassium alum (Taiwan Alum Company) and heat treatment at 60°C for 30 minutes. agent (C).

Embodiment one

1) Take 218.7g of 48% sodium hydroxide aqueous solution and slowly add 270g of acrylic acid and 291.6g of water into a 3000c.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 keep the temperature of the neutralization reaction system in the bottle within the range of 20°C to 40°C; at this time, an aqueous solution with a monomer concentration of 42wt% was obtained, in which 70mol% (molar ratio) of acrylic acid was partially neutralized to become sodium acrylate.

2) Add 0.414g of N,N'-methylenebisacrylamide and 0.781g of blowing agent (A) to the water-soluble unsaturated monomer solution, and keep the temperature at about 20°C.

3) Add 0.144g hydrogen peroxide, 1.8g sodium bisulfite and 1.8g ammonium persulfate starter to react.

4) The gel body generated after the reaction is chopped with a cutting mill, and the gel body whose particle size is less than 2 mm in diameter is screened out.

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

6) Take 100 g of the powdered superabsorbent resin obtained in the above step 5, add ethylene glycol, 1,4-butanediol (manufactured by Taiwan Plastics Corporation) and methanol to mix 2.5 g of aqueous solution in a volume ratio of 1:1:0.5, and Heat treatment at 150°C for 1 hour, and after cooling, a high-performance superabsorbent resin can be obtained. The measured holding power is 32.7g/g, the water absorption rate under the pressure of 20g/ ^cm2 is 29.6g/g, the water absorption rate under the pressure of 49g/ ^cm2 is 19.4g/g, the water content is 0.92%, and the VI value is 28.56sec/g.

Embodiment two

Repeat embodiment one, but the addition of blowing agent (A) is brought up to 11.72g. The rest are the same as in Example 1 to obtain a high-performance superabsorbent resin. The measured retention force is 31.5g/g, the water absorption capacity under 20g/ ^cm2 pressure is 30.2g/g, and the water absorption rate under 49g/ ^cm2 pressure is 19.7g/g. The ratio was 1.12%, and the VI value was 20.75 sec/g.

Embodiment three

Example one was repeated, but using blowing agent (B) instead of blowing agent (A). The rest are the same as in Example 1 to obtain a high-performance superabsorbent resin. The measured retention force is 30.9g/g, the water absorption capacity under 20g/ ^cm2 pressure is 29.4g/g, and the water absorption rate under 49g/ ^cm2 pressure is 18.7g/g. The ratio was 1.23%, and the VI value was 21.47 sec/g.

Embodiment four

Repeat embodiment three, but the addition of foaming agent (B) is increased to 3.91g. The rest are the same as in Example 3, high-performance superabsorbent resin can be obtained, the measured retention force is 31.5g/g, the water absorption rate under 20g/ ^cm2 pressure is 29.1g/g, and the water absorption rate under 49g/ ^cm2 pressure is 18.7g/g, The water content was 1.08%, and the VI value was 20.02 sec/g.

Embodiment five

Example one was repeated, but using blowing agent (C) instead of blowing agent (A). The rest is the same as in Example 1 to obtain a high-performance superabsorbent resin. The measured retention force is 31.2g/g, the water absorption capacity under 20g/ ^cm2 pressure is 28.9g/g, and the water absorption rate under 49g/ ^cm2 pressure is 19.1g/g. The ratio was 1.14%, and the VI value was 25.71 sec/g.

Embodiment six

Repeat Example 1, use 0.391g blowing agent (C) and 0.391g blowing agent (A) simultaneously. The rest is the same as in Example 1 to obtain a high-performance superabsorbent resin, measured at 32.1g/g, the water absorption rate under 20g/ ^cm2 pressure is 29.2g/g, the water absorption rate under 49g/ ^cm2 pressure is 18.9g/g, and the water content is 1.12 %, VI value is 26.45sec/g.

Embodiment seven

1) Take 218.7g of 48% sodium hydroxide aqueous solution and slowly add 270g of acrylic acid and 291.6g of water into a 3000c.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 keep the temperature of the neutralization reaction system in the bottle within the range of 20°C to 40°C; at this time, an aqueous solution with a monomer concentration of 42 parts by weight is obtained, in which 70mol% (molar ratio) of acrylic acid is partially neutralized to become sodium acrylate.

2) Add 0.414g of N,N'-methylenebisacrylamide and 0.781g of foaming agent (C) to the water-soluble unsaturated monomer solution, and keep the temperature at about 20°C.

3) Add 0.144g hydrogen peroxide, 1.8g sodium bisulfite and 1.8g ammonium persulfate starter to react.

4) The gel body generated after the reaction is chopped with a cutting mill, and the gel body whose particle size is less than 2 mm in diameter is screened out.

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

6) Take 100g of superabsorbent resin, add ethylene glycol, 1,4-butanediol (manufactured by Taiwan Plastics Corporation) and methanol 1/1/0.5 mixed aqueous solution 2.5g, heat treatment at 150°C for 1 hour, after cooling , take 10g of this superabsorbent resin by weighing, add 0.1g of silicon dioxide powder, after mixing evenly, add polyethyleneimine: water=1:3 (weight ratio) solution 1.2g, carry out anti-caking treatment, to obtain High-performance superabsorbent resin. The measured holding power is 31.5g/g, the water absorption rate under 20g/ ^cm2 pressure is 28.4g/g, the water absorption rate under 49g/ ^cm2 pressure is 19.1g/g, the water content is 2.13%, and the VI value is 24.37sec/g.

Embodiment eight

Example seven was repeated, but using blowing agent (B) instead of blowing agent (C). The rest are the same as in Example 1 to obtain a high-performance superabsorbent resin. The measured retention force is 30.9g/g, the water absorption capacity under 20g/ ^cm2 pressure is 29.4g/g, and the water absorption rate under 49g/ ^cm2 pressure is 19.3g/g. The ratio was 2.31%, and the VI value was 23.98 sec/g.

Comparative example one

Repeat embodiment one, use 1.4g calcium carbonate (Taiwan Plastics Company, product name: FP-100A). The rest are the same as in Example 1 to obtain a high-performance superabsorbent resin. The measured retention force is 32.2g/g, the water absorption capacity under 20g/ ^cm2 pressure is 28.7g/g, and the water absorption rate under 49g/ ^cm2 pressure is 17.4g/g. The ratio was 1.01%, and the VI value was 42.71 sec/g.

Comparative example two

Repeat Comparative Example 1, but replace calcium carbonate with sodium bicarbonate (China Red Triangle Company, product name: AK-28). The rest are the same as in Comparative Example 1 to obtain a high-performance superabsorbent resin. The measured retention force is 32.8g/g, the water absorption rate under 20g/ ^cm2 pressure is 28.4g/g, and the water absorption rate under 49g/ ^cm2 pressure is 17.1g/g. The ratio was 1.03%, and the VI value was 43.55 sec/g.

Comparative example three

Repeat comparative example two, but the addition amount of sodium bicarbonate reaches 2.8g. The rest is the same as in Comparative Example 2 to obtain a high-performance superabsorbent resin. The measured retention force is 32.5g/g, the water absorption capacity under 20g/ ^cm2 pressure is 25.6g/g, and the water absorption rate under 49g/ ^cm2 pressure is 10.7g/g. The ratio was 1.17%, and the VI value was 40.21 sec/g.

Comparative example four

Repeat comparative example two, but potassium alum (Taiwan Alum Company) replaces calcium carbonate. The rest are the same as in Comparative Example 2 to obtain a high-performance superabsorbent resin. The measured retention force is 28.7g/g, the water absorption rate under 20g/ ^cm2 pressure is 29.4g/g, and the water absorption rate under 49g/ ^cm2 pressure is 19.8g/g. The ratio was 1.26%, and the VI value was 51.72 sec/g.

Comparative example five

Repeat Comparative Example 2, but use calcined kaolin (China Guangying Company, product name: GF-60) instead of calcium carbonate. The rest is the same as in Comparative Example 2 to obtain a high-performance superabsorbent resin. The measured retention force is 29.1g/g, the water absorption rate under 20g/ ^cm2 pressure is 27.6g/g, and the water absorption rate under 49g/ ^cm2 pressure is 16.2g/g. The ratio was 1.13%, and the VI value was 49.37 sec/g.

Claims (7)

1. A manufacturing method of superabsorbent resin, comprising: (a) in a water-soluble unsaturated monomer containing an acid group monomer, the neutralization ratio is in the range of 45mol% to 85mol%, and the concentration is in an aqueous solution in the range of 20wt% to 55wt%; (b) Adding 0.01wt% to 10wt% of the total amount of the resin as a foaming agent for the mixture of carbonate compounds and alum compounds treated by coating to carry out polymerization reaction; (c) The hydrogel obtained after the polymerization reaction is sheared, granulated, dried, pulverized, and screened with hot air at a temperature of 100°C to 180°C; (d) After being coated with a surface cross-linking agent accounting for 0.005wt%-5wt% of the total resin, the surface is treated by heating at a temperature of 80°C to 230°C. 2. The method for producing a superabsorbent resin according to claim 1, wherein the carbonate compound is a compound having a carbonate group or a bicarbonate group in its chemical structure. 3. The method for producing a superabsorbent resin according to claim 1, wherein the alum-based compound is potassium alum, sodium alum, or ammonia alum containing crystal water. 4. The method for producing a superabsorbent resin according to claim 1, wherein the weight mixing ratio of the carbonate compound and the alum compound is 5:95 to 95:5. 5. The method for producing a superabsorbent resin according to claim 1, wherein a treatment temperature during the coating treatment is 40°C to 95°C. 6. The method for producing a superabsorbent resin according to claim 1, wherein the vortex extinction index of the produced superabsorbent resin is not more than 35 sec/g. 7. The method for producing a superabsorbent resin according to claim 1, wherein the retention force of the superabsorbent resin is not less than 20g/g, and the water absorption capacity under a pressure of 49g/ ^cm2 is not less than 12g/g .

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