TW201339231A - Manufacturing method of superabsorbent resins - Google Patents

Abstract

The present invention provides a manufacturing method of superabsorbent resin, comprising: mixing a mixed base, water, starch, and then with an unsaturated monomer component to form a reaction solution, polymerizing the reaction solution, and drying. Werein, the unsaturated monomer component including an alkene monomer with carboxyl groups, and the mixed base is a composition of an alkali metal compound and an alkaline earth metal compound. Werein, 5 to 15 mol% of alkene monomer with carboxyl group is neutralized by the alkaline earth metal compound. The manufacturing method can effectively improve water absorption, degradation rate and ability to promote plant growth of the resulting superabsorbent resin.

Description

Method for preparing super absorbent resin

The invention relates to a method for preparing a resin, in particular to a method for preparing a super absorbent resin, which is suitable for use in the technical fields of agriculture, forestry and the like.

Superabsorbent resin is a polymer material with high water absorption and water retention. It has been widely used in agriculture, forestry, medical, petroleum, chemical, chemical, building materials, food and other fields. It is used in superabsorbent resins for agriculture and forestry. There are widespread problems such as high cost and less additional functionality.

The method for producing a super absorbent resin for agriculture and forestry is mainly characterized by using an unsaturated ethylenic monomer (such as acrylic acid, acrylamide, etc.) as a main raw material, and after performing a copolymerization crosslinking reaction by adding a crosslinking agent and an initiator, After cutting, granulating, surface crosslinking, surface treatment and other procedures. However, such superabsorbent resins have the disadvantage of being difficult to decompose in the soil.

Some people have grafted copolymerization of starch and cellulose derivatives with acrylic acid, acrylamide, styrene, and then cross-linked with barium sulfate or ammonium sulfate to obtain a decomposable super absorbent resin for agriculture and forestry. However, its disadvantage is that barium sulfate is toxic, expensive, and complicated in manufacturing processes.

Chinese patents CN 1912006A and CN 1912007A disclose a method for obtaining a highly water-absorptive resin for agriculture and forestry using materials such as humic acid, acrylic acid and starch, but the highly water-absorbent resin obtained by the method can absorb water during soil cultivation application. The rate is too fast, and the uniformity of mixing with the soil is lowered, resulting in a decrease in applicability; and the starch needs to be gelatinized before being used, which is more energy and manufacturing cost.

In addition, the Chinese patent CN 101275004A discloses a method for producing a water retaining agent using attapulgite, humic acid and acrylic acid as raw materials. Although inorganic soil is used to reduce the cost, the overall water absorption ratio of the inorganic soil is low due to the low water absorption ratio of the inorganic soil. Good; and the method requires secondary drying, which is more energy-consuming.

Therefore, the development of an energy-saving method for a superabsorbent resin which has a good water absorption ratio and a water absorption rate and is easily degraded in the soil is sought by the industry.

Therefore, in view of the foregoing problems, the object of the present invention is to provide a process for preparing a superabsorbent resin comprising mixing a mixed base, water and starch, and mixing with an unsaturated monomer component to form a reaction solution, and The reaction solution is subjected to polymerization and drying, wherein the unsaturated monomer component comprises a carboxyl group-containing ethylenic monomer; the mixed base is a combination of an alkali metal compound and an alkaline earth metal compound; The neutralized carboxyl group-containing olefin monomer accounts for 5 to 15 mol% of the carboxyl group-containing olefin monomer.

The effect of the invention is that the superabsorbent resin obtained by the action of the mixed alkali and the starch containing the alkaline earth metal compound has better water absorption property than the conventional one, and the preparation method is simple and energy-saving, and can effectively improve the high water absorption of agriculture and forestry. Resin process technology.

The super absorbent resin of the present invention comprises the steps of: mixing a mixed base, water and starch, mixing with an unsaturated monomer component to form a reaction liquid, and subjecting the reaction liquid to polymerization and drying, wherein the unsaturated liquid is unsaturated. The monomer component comprises a carboxyl group-containing ethylenic monomer; the mixed base is a combination of an alkali metal compound and an alkaline earth metal compound; the carboxyl group-containing ethylenic monomer neutralized by the alkaline earth metal compound accounts for the carboxyl group-containing 5 to 15 mol% of the ethylenic monomer.

In the present invention, the method is to directly gelatinize the starch by utilizing the heat energy generated when the mixed alkali aqueous solution is hydrated with the starch, and neutralize the carboxyl group-containing ethylenic monomer to form the reaction liquid.

Compared with the hydrolysis between the alkali metal compound and the acrylic acid, the hydrolysis rate between the alkaline earth metal compound and the acrylic acid in the preparation method of the invention is slow, and the water absorption expansion rate of the obtained super absorbent resin is also slow, which can effectively avoid The occurrence of soil clumps makes the superabsorbent resin easier to mix evenly with the soil to enhance its application efficiency.

Preferably, the alkaline earth metal compound is selected from the group consisting of alkaline earth metal hydroxides, alkaline earth metal carbonates, or combinations thereof. More preferably, the alkaline earth metal compound is selected from the group consisting of calcium hydroxide, magnesium hydroxide, calcium carbonate, magnesium carbonate or a combination thereof. Because calcium ions and magnesium ions are trace elements required for plant growth (calcium ions can regulate cell membrane permeability and constitute plant cell walls and help other elements to absorb; magnesium ions are the central ions that make up plant chlorophyll and can catalyze some enzymes. By reacting, promoting seed germination and promoting sugar synthesis), the addition of the alkaline earth metal compound can also effectively enhance the ability of the superabsorbent resin to promote plant growth. In a particular embodiment of the invention, the alkaline earth metal compound is calcium hydroxide.

If the amount of the alkaline earth metal compound used is too small, the effect of slowing the water absorption rate is not remarkable; if the amount used is too large, the degree of crosslinking of the superabsorbent resin is too high and the water absorption ratio is lowered, so that an appropriate amount of use is required. Preferably, the carboxyl group-containing ethylenic monomer neutralized by the alkaline earth metal compound accounts for 5 to 14 mol% of the carboxyl group-containing ethylenic monomer.

Preferably, the carboxyl group-containing ethylenic monomer may be selected from the group consisting of acrylic acid, methacrylic acid, maleic acid, fumaric acid, crotonic acid, and itaconic acid. ) or a combination thereof.

Preferably, the unsaturated monomer component further comprises an amidino group-containing ethylenic monomer. The mercapto group-containing ethylenic monomer can enhance the absorption capacity of the superabsorbent resin when the water quality is hard. Preferably, the acyl group-containing vinyl monomer selected from acrylamide, N - vinyl as acetamide (N -vinyl acetamide), methyl acrylamide (methacrylamide), N, N - dimethyl N , N- dimethyl methacrylamide or a combination thereof. In a particular embodiment of the invention, the guanamine containing olefinic monomer is acrylamide.

Preferably, the unsaturated monomer component further comprises a sulfonic acid group-containing ethylenic monomer. The sulfonic acid group-containing olefin monomer can enhance the absorption capacity of the super absorbent resin. Preferably, the sulfonic acid group-containing ethylenic monomer may be selected from the group consisting of vinyl sulfonic acid, 2-acrylamido-2-methylpropane sulfonic acid (2-acrylamido-2-methylpropane sulfonic acid). Acid, AMPS), methacryloxyalkane sulfonic acid or a combination thereof. In a particular embodiment of the invention, the sulfonic acid group-containing olefinic monomer is 2-acrylamido-2-methylpropane sulfonic acid.

If the ratio of the carboxyl group-containing ethylenic monomer neutralized by the mixed alkali is too low, the water absorption ratio of the obtained super absorbent resin is not good, and a large amount of use is required in application to achieve a predetermined effect; if it is neutralized If the ratio is too high, the acidity and alkalinity of the resulting highly water-absorptive resin is unfavorable for plant growth. Preferably, the carboxyl group-containing ethylenic monomer neutralized by the mixed base accounts for 30 to 85 mol%, more preferably 30 to 75 mol%, of the carboxyl group-containing ethylenic monomer. In a specific embodiment of the present invention, the carboxyl group-containing ethylenic monomer neutralized by the mixed base accounts for 35 to 65 mol% of the carboxyl group-containing ethylenic monomer.

In order to enhance the degree of degradability of the superabsorbent resin produced by the present invention, the present invention attempts to incorporate starch into the copolymer to participate in the copolymerization. If the amount of starch used is too small, the effect is not good; if the amount of starch used is too large, the water absorption ratio of the obtained super absorbent resin is lowered. Preferably, the weight ratio of the carboxyl group-containing monomer to the starch ranges from 10:1 to 3.3:1. In a specific embodiment of the invention, the weight ratio of the carboxyl group-containing monomer to the starch ranges from 10:1 to 5:1.

In order to enhance the efficacy of the superabsorbent resin produced by the present invention for promoting plant growth, the reaction solution may further comprise a humic acid derivative. Humic acid derivatives have functions such as enhancing fertilizer effects, improving soil, and stimulating plant growth. Preferably, the humic acid derivative is selected from the group consisting of humic acid, humate or a combination thereof. In a particular embodiment of the invention, the humic acid derivative is humic acid.

The present invention attempts to obtain a superabsorbent resin by adding humic acid to the reaction liquid to carry out a reaction, followed by drying.

If the amount of the humic acid derivative used is too small, the effect is not good; if it is used in an excessive amount, the cost is increased. Preferably, the weight ratio of the carboxyl group-containing ethylenic monomer to the humic acid derivative ranges from 100:1 to 10:1.

The ethylenic monomer of the present invention may be added with a radical polymerization crosslinking agent in the reaction monomer solution before the radical polymerization reaction, so that the obtained super absorbent resin has an appropriate degree of crosslinking, thereby adjusting its Mechanical and processing properties. The crosslinking agent may be selected from: (1) a compound having two or more unsaturated double bonds, for example: N , N '-bis(2-propenyl)amine, N , N '-methylcyclopropene ,amine ( N , N '-methylenebisacrylamide), N , N '-methyl dimethyl methacrylate, propylene acrylate, ethylene glycol diacrylate, polyethylene glycol diacrylate, ethylene glycol Acrylate, polyethylene glycol dimethacrylate, glycerol triacrylate, glycerol trimethacrylate, ethoxylated glycerol triacrylate or trimethacrylate, ethoxylated trimethylolpropane Ethoxylated trimethylolpropane trimethacrylate, ethoxylated trimethylolpropane triacrylate (ethoxylated TMPTA), trimethylolpropane trimethacrylate, trimethylolpropane triacrylate Ester, N , N , N -tris(2-propenyl)amine, ethylene glycol diacrylate, polyoxyethylene glyceryl triacrylate, diethyl polyoxyethylene glyceryl triacrylate, dipropylene triethylene glycol ester, etc. (2) has two or more rings Alkoxy compounds such as glycerol polyethylene glycol triglycidyl ether, sorbitol polyglycidyl ether, polyglycerol polyglycidyl ether, ethylene glycol diglycidyl ether, diethylene glycol diglycidyl ether , polyethylene glycol diglycidyl ether, diglycerol polyglycidyl ether and the like. These crosslinking agents may be used singly or in combination of two or more. In a particular embodiment of the invention, the crosslinking agent is ethoxylated trimethylolpropane triacrylate.

If the amount of the crosslinking agent used is too small, the resulting highly water-absorptive resin is soft and sticky, which is disadvantageous for subsequent mechanical processing; if the crosslinking agent is used in an excessive amount, the superabsorbent resin is lowered. Water absorption performance. Preferably, the crosslinking agent is used in an amount ranging from 0.001 to 5 wt% (100 wt% based on the total solid portion of the reactant), more preferably from 0.01 to 3 wt%.

The radical initiator of the present invention for use in the radical polymerization may be optionally a thermally decomposable initiator, and the suitable thermally decomposable initiator comprises a peroxide such as hydrogen peroxide or Di- tert -butyl peroxide (DTBP), persulfate, etc., and azo compounds such as 2,2'-azobis(2-amidinopropane) di-salt Acid salt [2,2'-azobis(2-amidinopropane) dihydrochloride, AAPH], 2,2'-azobis(2-methylpropionitrile), azobisisobutyronitrile, AIBN], etc. A redox type initiator such as bisulfite, thiosulfate, L-ascorbic acid, ferrous salt or the like can be used. In a particular embodiment of the invention, the starter is a combination of L-ascorbic acid, sodium persulfate and 2,2'-azobis(2-amidinopropane) dihydrochloride.

If the amount of the initiator used is too small, the reaction rate is too slow; if the amount of the initiator used is too large, it is difficult to control the reaction. Preferably, the initiator is used in an amount ranging from 0.001 to 10% by weight (based on the weight of the carboxyl group-containing ethylenic monomer neutralized by the mixed base to 100% by weight), more preferably 0.01 to 5% by weight.

The polymerization of the ethylenic monomer of the present invention can be carried out in a conventional batch reaction vessel, a conveyor belt reactor, or a kneader having a uniaxial or biaxial.

Preferably, the superabsorbent resin may be cut into a resin powder having a volume of 10 cm ³ or less by a pulverizer before the drying step of the method of the present invention, and then subjected to screening. The size of the resin powder to be screened is preferably less than 2 cm. Since the resin powder having a size larger than 2 cm is likely to be poor in heat conduction during subsequent drying, the residual monomer content is high and the physical properties are not good, so Return to the shredder for shredding. Further, the more concentrated the particle size distribution of the superabsorbent resin powder, the better the physical properties of the superabsorbent resin after the subsequent drying, and the time and temperature for controlling the drying.

Preferably, the drying temperature of the process of the present invention ranges from 100 to 180 °C. If the drying temperature is lower than 100 ° C, the process will be too time consuming; if the drying temperature is higher than 180 ° C, the crosslinking agent will crosslink prematurely, making it difficult to be effective due to excessive crosslinking in the drying process. Remove residual monomers. In a particular embodiment of the invention, the drying temperature is 130 °C.

The invention is further described in the following examples, but it should be understood that these examples are for illustrative purposes only and are not to be construed as limiting.

<Example 1>

The method for producing the super absorbent resin of Example 1 comprises the steps of:

(1) Take 10.42 g of 48 wt% sodium hydroxide solution and 0.77 g of calcium hydroxide in a 100 mL Erlenmeyer flask, then add 3 g of starch (purchased from Weidan Enterprise) with 10 g of deionized water and stir. After about 30 minutes, after the starch was gelatinized, add 3 g of acrylamide (purchased from Jingming Chemical Company) and 22.4 g of deionized water and stir for about 30 minutes, then slowly add 30 g of acrylic acid under ice bath (source is Taiwan Plastics Industry Co., Ltd.) to carry out neutralization to obtain a reaction monomer solution; wherein 35 mol% of acrylic acid is neutralized to be an acrylate.

(2) Further, 0.046 g of ethoxylated TMPTA was added to the above reaction monomer solution and stirred to obtain a reaction liquid, and the temperature was maintained at about 20 °C.

(3) Add 0.016 g of L-ascorbic acid, 0.2 g of sodium persulfate and 0.2 g of 2,2'-azobis(2-amidinopropane) dihydrochloride in the above reaction solution to initiate the reaction, and the reaction is about 1 A resin was obtained after an hour.

(4) The resin was cut into a resin powder having a size of 2 mm or less by a cutter mill (purchased from Rixi Co., model 200).

(5) The above resin powder was dried at 130 ° C for 2 hours, and a resin powder having a size ranging from 0.1 to 0.85 mm was sieved by a sieve.

<Example 2>

The preparation method and examples of Example 2 were carried out except that the amount of the aqueous sodium hydroxide solution and the calcium hydroxide in the step (1) were changed to 17.70 g and 2.15 g, respectively, wherein 65 mol% of the acrylic acid was neutralized to be an acrylate. 1 is the same.

<Example 3>

The amount of the aqueous solution of sodium hydroxide and calcium hydroxide in the step (1) was changed to 15.63 g and 2.32 g, respectively (60 mol% of the acrylic acid was neutralized to be an acrylate), and the starch in the step (1) After the gelatinization, 3 g of 2-acrylamido-2-methylpropanesulfonic acid (AMPS, purchased from Jingming Chemical Co., Ltd.) was additionally added, and the production method of Example 3 was the same as in Example 1.

<Example 4>

The preparation method and examples of Example 4 were carried out except that the amount of the aqueous sodium hydroxide solution and the calcium hydroxide in the step (1) were changed to 19.09 g and 0.77 g, respectively, wherein 60 mol% of the acrylic acid was neutralized to be an acrylate. 1 is the same.

<Example 5>

The preparation method of Example 5 was the same as that of Example 4 except that 0.3 g of humic acid (HA, purchased from Yuhua Industrial Co., Ltd.) was additionally added to the reaction liquid of the step (2).

<Example 6>

The preparation method of Example 6 was the same as that of Example 5 except that the amount of the humic acid in the step (2) was changed to 3 g.

<Example 7>

The preparation method of Example 7 was carried out except that the reaction monomer solution of the step (2) was changed to be placed in a uniaxial kneader (purchased from Qiyan Co., model JY N-05) and stirred at 70 rpm. The same as in the first embodiment.

< Example 8>

The production method of Example 8 was the same as that of Example 1 except that the amount of the starch of the step (1) was changed to 6 g.

< Water absorption rate determination>

The method for measuring the water absorption ratio of the present invention is as follows: X g superabsorbent resin is placed in a mesh bag of mesh of 250 mesh, and the bag is immersed in deionized water for 60 minutes, and then the bag is taken out to Allow to stand in the air for 15 minutes, and finally measure the mass (Y g); in addition, a set of mesh bags without superabsorbent resin is also immersed in deionized water, and the weight (Z g) is left blank after hanging according to the above steps. Subtract and repeat 3 sets of tests to find the average. The absorption ratio of the super absorbent resin in the net bag can be calculated according to the following formula.

Absorption ratio of superabsorbent resin =

< Vortex disappearance time measurement>

The method for determining the vortex disappearance time of the present invention is as follows: 50 mL of a 0.9 wt% aqueous solution of sodium chloride is added to a 100 mL beaker. Place the electromagnetic stir bar and place the beaker on the electromagnetic stirrer and set it to 600 rpm. A 2.000 ± 0.001 g superabsorbent resin was weighed on an analytical balance, poured into a beaker and timed, and the time (in seconds) required for the vortex to disappear was recorded.

< Colloid strength measurement>

The invention utilizes a constant temperature and humidity device to make the super absorbent resin in a high temperature and high humidity environment to simulate the decomposition of the super absorbent resin in the soil environment. The method for determining the strength of the colloid of the present invention is as follows: 1.000±0.001 g of the super absorbent resin is slowly added to 100 mL of deionized water, and stirred on an electromagnetic stirrer for 1 minute, and then placed into a hydrocolloid and then placed in a constant temperature. Hygrostat (purchased from Xinqianxiang Company, model AJH-80, test conditions are 90 ° C and 70% relative humidity) for 1 hour, and then STEVENS colloidal strength tester (purchased from Quanhua Precision Co., model) The colloidal strength was measured for CNS FARNELL TA1000) (set the drop speed of the suspension column to 1.0 mm/sec and the drop distance to 25 mm). The above procedure was repeated, but the aqueous colloid was placed in a thermo-hygrostat for 168 hours, and then the colloidal strength was measured.

The resin powders obtained in the above Examples 1 to 8 were subjected to the above-described water absorption ratio measurement, vortex disappearance time measurement, and colloidal strength measurement, respectively, and the main components and measurement results thereof are shown in Table 1 below.

<Comparative Example 1>

In addition to changing the amount of the aqueous sodium hydroxide solution of the step (1) to 20.8 g (where 60 mol% of the acrylic acid is neutralized to be an acrylate), and without adding calcium hydroxide and starch, the preparation and implementation of Comparative Example 1 Example 1 is the same.

<Comparative Example 2>

The preparation method of Comparative Example 2 and Example 1 except that the amount of the aqueous sodium hydroxide solution of the step (1) was changed to 20.8 g (where 60 mol% of acrylic acid was neutralized to be an acrylate), and calcium hydroxide was not added. the same.

<Comparative Example 3>

Except that the amount of the aqueous sodium hydroxide solution of the step (1) was changed to 12.2 g (35 mol% of the acrylic acid was neutralized to be an acrylate), the amount of the starch was changed to 6 g, and no calcium hydroxide was added. The preparation method of Comparative Example 3 was the same as that of Example 1.

<Comparative Example 4>

Comparative Example 4 was prepared in the same manner as in Example 3 except that starch and AMPS were not added in this step (1).

< Comparative Example 5>

The superabsorbent resin of Comparative Example 5 was prepared according to the method of Example 3 of Chinese Patent No. CN 101275004A: 40 g of acrylic acid was placed in a reactor, dissolved by adding 408.91 g of deionized water, and the aqueous solution was adjusted with 31.09 g of potassium hydroxide. The pH value is up to 7, and 20 g of acrylamide is dissolved in 100 g of deionized water to prepare an aqueous solution of acrylamide, and added to the neutralized aqueous solution of acrylic acid, and then 50 g of attapulgite and 0.2 g of sodium persulfate are separately added. 0.1 g of sodium sulfite, 0.05 g of N , N -methylenebisacrylamide, 0.2 g of triethanolamine and uniformly mixed. Nitrogen gas was introduced into the reactor for 30 minutes, and polymerization was carried out at 70 ° C for 2 hours to obtain a gel product. The gelatinous product was chopped, dried, and pulverized to obtain a powdery acrylic-acrylamide copolymer. 5 g of a powdery acrylic-acrylamide copolymer was sprayed with 10 g of a 13% by weight aqueous solution of humic acid, and dried in a dry box at 60 ° C for 20 minutes to obtain a super absorbent resin of Comparative Example 5.

<Comparative Example 6>

The superabsorbent resin of Comparative Example 6 was prepared according to the method of Example 1 of Chinese Patent No. CN 1912006A: 10 g of coal humic acid was dissolved in 200 mL of a 4% by weight NaOH solution to prepare a sodium humate solution. The supernatant was taken, and 21 g of starch was added to 39 g of deionized water and gelatinized at 80 ° C to prepare a hydrogel. 50 g of acrylic acid was neutralized with a 20% by weight NaOH solution to a neutralization degree of 75%. The above three groups were sequentially added to the container, and then 18 g of 0.8% N,N -methylenebispropene decylamine was added and stirred uniformly, and 36 g of a 4% potassium persulfate aqueous solution was gradually stirred. Add it, keep the water bath temperature at 60 ° C, stop when the reaction forms a viscous gel product, take out the product and cool it to room temperature, cut into 5~10 mm pieces and put it in an oven at 80 ° C for 24 hours to constant weight. The machine was pulverized, and sieved at a certain particle size to obtain the super absorbent resin of Comparative Example 6.

<Comparative Example 7>

The superabsorbent resin of Comparative Example 7 was prepared according to the method of Example 9 of Chinese Patent No. CN 101451056A: 115.2 g of acrylic acid, 227.2 g of 50% acrylamide aqueous solution and 562.5 g of water were added to a 1 L beaker, and cooled to 5 ° C. The solution was placed in an insulated polymerization tank and nitrogen gas was introduced to reduce the dissolved oxygen amount to 0.1 ppm, and 35% hydrogen peroxide 0.00016 g, L-ascorbic acid 0.00008 g and 4,4'-azobis(4-cyanoshikimate) were added. 0.04 g was used as the initiator, and the polymerization was completed after 5 hours. After the obtained polymer was kneaded by a kneader for about 2 hours, the mixture was further mixed with 17.8 g of a 50% calcium hydroxide dispersion and 113.3 g of a 48% aqueous sodium hydroxide solution, followed by stirring in a kneader for about 2 hours to carry out mixing. Thereafter, the mixture was dried at 120 ° C for 1 hour using a belt dryer, and pulverized to obtain a dry powder having an average particle diameter of 500 μm, which was further heated by a circulating air dryer at 160 ° C for 120 minutes to thermally crosslink, and Comparative Example 7 was obtained. Super absorbent resin (average particle size 3300 μm).

<Comparative Example 8>

The superabsorbent resin of Comparative Example 8 was prepared according to the method of Example 10 of Chinese Patent No. CN 101451056A: except for the use of acrylic acid, 50% acrylamide aqueous solution, 50% calcium hydroxide dispersion and 48% sodium hydroxide aqueous solution. Comparative Example 8 was prepared in the same manner as in Comparative Example 7 except that it was changed to 187.2 g, 71.0 g, 77.0 g, and 43.3 g, respectively (average particle diameter was 1800 μm).

The resin powders obtained in the above Comparative Examples 1 to 8 were subjected to the above-described water absorption ratio measurement, vortex disappearance time measurement, and colloidal strength measurement, respectively, and the main components and measurement results thereof are shown in Table 2 below.

From the results of Table 1 and Table 2, we can find:

(1) Water absorption ratio: The water absorption ratio of the super absorbent resin of Examples 1 to 8 was all 400 or more, indicating that the super absorbent resin obtained by the present invention has good water absorption properties. The water absorption ratio of the superabsorbent resin of Example 3 was 600 or more, indicating that the water absorption ratio of the obtained super absorbent resin can be remarkably improved by the addition of AMPS in the present invention.

(2) Vortex disappearing time: The vortex disappearing time of the highly water-absorbent resin of Examples 1 to 8 is between 105 and 688 seconds, which indicates that the superabsorbent resin obtained by the present invention has a suitable water absorption rate, presumably because it is It is prepared by containing 15 mol% or less of acrylic acid neutralized with calcium hydroxide; in comparison, the acrylic monomers used in the superabsorbent resins of Comparative Examples 1 to 3 and Comparative Examples 5 to 6 do not contain The calcium hydroxide neutralizes the obtained acrylate, so the vortex disappearing time is less than 100 seconds, indicating that the water absorption rate is too fast, which is disadvantageous for the dispersibility required when applied to the soil, thereby causing agglomeration; The superabsorbent resin of Comparative Example 8 was prepared from acrylic acid containing 40 mol% of calcium hydroxide neutralized, and thus had a long vortex disappearing time (1450 seconds), indicating that its water absorption rate was extremely slow, and The manufacturing process contains a large amount of calcium ions, resulting in poor water absorption ratio (205) and low production efficiency.

(3) Colloidal strength: The superabsorbent resin of Examples 1 to 8 has a colloidal strength of less than 50 g after 168 hours in a high-temperature and high-humidity environment, indicating that the superabsorbent resin obtained by the present invention is high-temperature and high-humidity. It is easy to degrade under the soil environment and is not easy to cause environmental burden. It is presumed to be caused by the addition of starch during the manufacturing process; in comparison, the super absorbent resin of Comparative Example 1, Comparative Examples 4 to 5 and Comparative Examples 7 to 8 No starch is added during the manufacturing process, so the colloidal strength after 168 hours in a high temperature and high humidity environment is maintained above 150 g, and the degradation rate is relatively slow.

In addition, the present invention utilizes the exothermic heat of hydration of the mixed alkali to facilitate gelatinization of the starch for subsequent reaction, and is an energy-saving method for producing a highly water-absorbent resin. Compared with the method disclosed in Chinese Patent No. 101275004A (after drying the super absorbent resin, spraying the humic acid aqueous solution on the surface of the superabsorbent resin and performing secondary drying), the present inventions 5 to 6 show that the use is The reaction of the monomer solution in the step (2), that is, the addition of humic acid, is more energy-efficient and simpler than the method disclosed in the aforementioned patent.

In summary, the method for producing the super absorbent resin of the present invention has the characteristics of energy saving and simplicity, can effectively improve the production efficiency and improve the degradation rate of the super absorbent resin obtained therefrom, and the high water absorption thereof is obtained. The resin has excellent water absorption ratio and water absorption rate, and a humic acid derivative can be further added to promote plant growth.

The above is only the preferred embodiment and the specific examples of the present invention, and the scope of the invention is not limited thereto, that is, the simple equivalent change according to the scope of the invention and the description of the invention. And modifications are still within the scope of the invention patent.

Claims (9)

The invention relates to a method for preparing a super absorbent resin, comprising: mixing a mixed base, water and starch, mixing with an unsaturated monomer component to form a reaction liquid, and subjecting the reaction liquid to polymerization reaction and drying, wherein the The saturated monomer component comprises a carboxyl group-containing ethylenic monomer; the mixed base is a combination of an alkali metal compound and an alkaline earth metal compound; and the carboxyl group-containing ethylenic monomer neutralized by the alkaline earth metal compound accounts for the carboxyl group 5 to 15 mol% of the ethylenic monomer. The method for producing a super absorbent resin according to claim 1, wherein the alkaline earth metal compound is selected from the group consisting of alkaline earth metal hydroxides, alkaline earth metal carbonates, or a combination thereof. The method for producing a super absorbent resin according to claim 2, wherein the alkaline earth metal compound is selected from the group consisting of calcium hydroxide, magnesium hydroxide, calcium carbonate, magnesium carbonate or a combination thereof. The method for producing a super absorbent resin according to claim 1, wherein the unsaturated monomer component further comprises a sulfonic acid group-containing ethylenic monomer. The method for producing a super absorbent resin according to claim 4, wherein the sulfonic acid group-containing ethylenic monomer is 2-acrylamido-2-methylpropanesulfonic acid. The method for producing a super absorbent resin according to claim 1, wherein the carboxyl group-containing ethylenic monomer neutralized by the mixed base accounts for 30 to 65 mol% of the carboxyl group-containing ethylenic monomer. The method for producing a super absorbent resin according to claim 1, wherein the weight ratio of the carboxyl group-containing ethylenic monomer to the starch ranges from 10:1 to 3.3:1. The method for producing a super absorbent resin according to claim 1, wherein the reaction solution further comprises a humic acid derivative. The method for producing a super absorbent resin according to claim 8, wherein the weight ratio of the carboxyl group-containing ethylenic monomer to the humic acid derivative ranges from 100:1 to 10:1.