Bio-based super absorbent resin and preparation method thereof

Abstract

The invention relates to bio-based super absorbent resin and a preparation method thereof, and belongs to the technical field of polymer synthesis. The invention provides a bio-based super absorbent resin, the structural formula of which is as shown in formula I. In the formula I, x is equal to 0.300-0.600, y is equal to 0.100-0.300, z is equal to 0.102-0.600, x + y + z is equal to 1, a is equal to 0.001-0.01, and n is equal to 20-2000. The organic raw materials adopted in the invention are all 100% biological sources, and have the advantages of low carbon and environmental protection, and the obtained resin has the advantages of fast water absorption rate, high water absorption rate and good stability. # imgabs0 #

Description

Technical Field

[0001] The invention relates to a bio-based highly water-absorbent resin and a preparation method thereof, belonging to the technical field of polymer synthesis. Background Art

[0002] Water-absorbent materials are materials that can absorb several times or even thousands of times their own weight in water, and generally have porous and network structures. Traditional water-absorbent materials, such as fabrics and foams, can absorb up to about 20 times their own weight in water, and after absorbing water, the water is easily squeezed out under the action of external force. Super absorbent resin (SAP) is a type of polymer material that is insoluble in water and organic solvents, contains a large number of strong hydrophilic groups, and has a certain degree of cross-linking. It can absorb water from dozens to thousands of times its own weight. After absorbing water, super absorbent resin swells into a hydrogel, has excellent water retention, is not easy to lose water even if squeezed, and can still absorb water repeatedly after drying.

[0003] Bio-based super absorbent resins can be obtained by copolymerizing starch, cellulose, chitosan, humic acid and lignin from biological sources with acrylic acid, but most of these super absorbent resins are partially bio-based super absorbent resins and are easily decomposed by microorganisms and lose their water absorption and water retention functions. At the same time, chemically synthesized super absorbent resins represented by acrylic acid have the advantages of high water absorption rate and good stability.

[0004] Therefore, it is necessary to develop a highly stable 100% bio-based superabsorbent resin. Summary of the invention

[0005] The purpose of the present invention is to provide a bio-based super absorbent resin and a preparation method thereof in view of the deficiencies of the prior art. The invention is characterized in that methacrylic anhydride, amino acid and diamino compound are first reacted in water to obtain a mixed solution of methacrylic acid, methacrylamide carboxylic acid and a crosslinking agent; then itaconic acid, sodium hydroxide and / or methacrylic acid and water are added to prepare a mixed reaction solution, free radical polymerization occurs under the action of an initiator, and finally the obtained product is dried to obtain a fully bio-based super absorbent resin. Since the organic raw materials used in the present invention are all 100% biological in origin, it has the advantages of low carbon and environmental protection, and the obtained resin has the advantages of fast water absorption rate, high water absorption rate and good stability.

[0006] The technical solution of the present invention:

[0007] The first technical problem to be solved by the present invention is to provide a bio-based super absorbent resin, the structural formula of which is shown in Formula I:

[0008]

[0009] In formula I, x=0.300~0.600, y=0.100~0.300, z=0.102~0.600, x+y+z=1, a=0.001~0.01, n=20~2000;

[0010] R1=H, —CH3, —CH(CH3)2, —CH2CH(CH3)2, —CH(CH3)CH2CH3, —CH2CONH2,

[0011] —CH2CH2CONH2, —CH2COOM, —CH2CH2COOM, At least one of;

[0012] R2=—(CH2)5—,—(CH2)9—,—(CH2) 10 —, —(CH2) 13 — or —(CH2)4CH(COOM)—;

[0013] M=H or Na, the molar ratio of Na is 0.55~0.80; the wavy line represents the polymer chain.

[0014] The second technical problem to be solved by the present invention is to provide a method for preparing the above-mentioned bio-based super absorbent resin, which comprises: firstly reacting an amino acid, a diamino compound and methacrylic anhydride in water to obtain a mixed liquid; then adding itaconic acid, sodium hydroxide and / or methacrylic acid and water to prepare a mixed reaction liquid; then free radical polymerization is carried out under the action of an initiator to obtain a product; and finally, the obtained product is dried to obtain the bio-based super absorbent resin.

[0015] Furthermore, in the above preparation method, the ratio of each raw material is:

[0016] 75-612 parts by weight of amino acid, 1.0-21.4 parts by weight of diamino compound, 200-5000 parts by weight of water, 157.1-492.8 parts by weight of methacrylic anhydride, 390-780 parts by weight of itaconic acid, 0-240.8 parts by weight of methacrylic acid, 561-2880 parts by weight of sodium hydroxide aqueous solution, 1.0-20.0 parts by weight of oxidant, and 1.0-15.0 parts by weight of reducing agent.

[0017] Furthermore, in the above-mentioned method for preparing the bio-based super absorbent resin, the amino acid is selected from at least one of glycine, alanine, valine, leucine, isoleucine, asparagine, glutamine, aspartic acid, glutamic acid, phenylalanine or tryptophan.

[0018] Furthermore, in the above-mentioned method for preparing the bio-based super absorbent resin, the diamino compound is selected from at least one of pentamethylenediamine, nonanediamine, decanediamine, tridecanediamine or lysine.

[0019] Furthermore, in the above-mentioned method for preparing the bio-based super absorbent resin, the initiator is an oxidation-reduction initiator, comprising an oxidant and a reducing agent.

[0020] Furthermore, in the above-mentioned method for preparing the bio-based super absorbent resin, the oxidant is at least one of hydrogen peroxide, ammonium persulfate, potassium persulfate or sodium persulfate.

[0021] Furthermore, in the above-mentioned method for preparing the bio-based super absorbent resin, the reducing agent is at least one of sodium sulfite, sodium bisulfite, sodium thiosulfate or glucose.

[0022] Furthermore, the preparation method of the bio-based super absorbent resin comprises the following steps:

[0023] (1) adding 75-612 parts by weight of amino acid, 1.0-21.4 parts by weight of diamino compound and 200-2000 parts by weight of water into a reaction kettle equipped with a thermometer, nitrogen inlet and outlet pipes, a water cooling device and a shear stirrer, introducing nitrogen and starting stirring;

[0024] (2) cooling with water, adding 157.1 to 492.8 parts by weight of methacrylic anhydride dropwise over 0.5 to 1 hour, maintaining the temperature not exceeding 40° C.;

[0025] (3) adding 390 to 780 parts by weight of itaconic acid, 0 to 240.8 parts by weight of methacrylic acid and 0 to 3000 parts by weight of water, and dripping 561 to 2880 parts by weight of a 20 to 51 wt% aqueous sodium hydroxide solution over 0.5 to 1 hour, while maintaining the temperature at no more than 50° C.;

[0026] (4) cooling to 0-30° C., adding 1.0-20.0 parts by weight of an oxidant and 1.0-15.0 parts by weight of a reducing agent in sequence, and stirring until completely dissolved; heating to 60-100° C. within 0.5-1 hour, stopping nitrogen flow, stopping stirring, and keeping the temperature for reaction for 2-6 hours;

[0027] (5) Cooling, turning on the shear mixer to cut the material into gel particles, releasing the material, and drying to obtain a bio-based super absorbent resin.

[0028] Furthermore, in the above-mentioned method for preparing the bio-based super absorbent resin, all organic raw materials used are 100% of biological origin.

[0029] In the present invention, the parts of raw materials are all parts by weight unless otherwise specified.

[0030] Beneficial effects of the present invention:

[0031] 1. The present invention adopts 100% biologically derived organic raw materials to prepare bio-based super absorbent resin, which has the advantages of low carbon and environmental protection.

[0032] 2. The main raw material of the present invention, itaconic acid, has been industrialized, and the glutamic acid in the amino acid has a huge production capacity, and has the advantages of abundant raw material sources and low prices.

[0033] 3. The main raw material of the present invention, itaconic acid, is a dibasic unsaturated carboxylic acid, and its carboxyl content is twice that of a monobasic unsaturated carboxylic acid. The obtained bio-based super absorbent resin contains more water-absorbing groups and has the advantages of fast water absorption rate and high water absorption rate.

[0034] 4. The present invention uses diamino compounds with different carbon chain lengths to prepare crosslinking agents with different carbon chain lengths, and can flexibly adjust the crosslinking density and the size of the crosslinking grid. The obtained bio-based super absorbent resin has the advantages of adjustable network structure and good water absorption stability. DETAILED DESCRIPTION

[0035] The present invention provides a bio-based super absorbent resin and a preparation method thereof, which is characterized in that methacrylic anhydride, amino acids and diamino compounds are first reacted in water to obtain a mixed solution of methacrylic acid, methacrylamide carboxylic acid and a crosslinking agent; then itaconic acid, sodium hydroxide and / or methacrylic acid and water are added to prepare a mixed reaction solution, free radical polymerization occurs under the action of an initiator, and finally the obtained product is dried to obtain a fully bio-based super absorbent resin. Among them, itaconic acid is prepared by fermentation of sugar substances or converted from citric acid, and further catalytic decarboxylation is obtained to obtain methacrylic acid; methacrylic acid is dehydrated to obtain methacrylic anhydride, which is further reacted with amino acids to prepare methacrylamide carboxylic acid; among the diamino compounds, pentamethylenediamine is obtained by lysine enzyme catalytic decarboxylation, nonanediamine is obtained by oxidation and amination of oleic acid, decanediamine is obtained by amination of sebacic acid from castor oil, and tridecanediamine is obtained by oxidation and amination of erucic acid. Therefore, the organic raw materials used in the present invention are all 100% biologically derived, have the advantages of low carbon and environmental protection, and the obtained resin has the advantages of fast water absorption rate, high water absorption rate and good stability.

[0036] The present invention is described in detail below through examples. It is necessary to point out that the examples are only used to further illustrate the present invention and cannot be understood as limiting the scope of the present invention. Those skilled in the art can make some non-essential improvements and adjustments based on the contents of the present invention.

[0037] Example 1

[0038] 150g of glycine, 2.0g of pentamethylenediamine and 500g of water were added to a reactor equipped with a thermometer, a nitrogen inlet and outlet pipe, a water cooling device and a shearing stirrer, nitrogen was introduced, and stirring was started; water was passed for cooling, and 314.2g of methacrylic anhydride was added dropwise within 0.5 hours, maintaining the temperature not exceeding 40°C; then 650g of itaconic acid, 82.6g of methacrylic acid and 2300g of water were added, and 1500g of 30wt% sodium hydroxide aqueous solution was added dropwise to the reactor within 0.5 hours, maintaining the temperature not exceeding 50°C; the temperature was lowered to 30°C, 5.0g of ammonium persulfate and 2.5g of sodium sulfite were added in sequence, and stirred until completely dissolved; the temperature was raised to 80°C within 1 hour, the nitrogen was stopped, the stirring was stopped, and the reaction was kept warm for 5 hours; the temperature was lowered, the shearing stirrer was turned on to cut the material into gel particles, the material was discharged, and it was dried at 150°C to a water content of ≤0.2%, and a bio-based super absorbent resin was obtained, and the pure water absorption rate was: 211. The performance parameters of each embodiment are shown in Table 1.

[0039] Water absorption test: Take 3 portions of about 0.3g of bio-based super absorbent resin and add about 200g of pure water, saline (0.9% sodium chloride solution) and seawater (density 1.023g / cm 3 ) and soaked for 12 hours; filtered with a 100-mesh filter, and the ratio of the increased weight of the resin to the original weight is the corresponding water absorption rate. As shown in Table 1, the water absorption rates of the bio-based super absorbent resin obtained in Example 1 in pure water, physiological saline and seawater are 211, 45 and 20, respectively.

[0040] Example 2

[0041] 248.9g of leucine, 21.4g of tridecanediamine and 1500g of water were added to a reactor equipped with a thermometer, a nitrogen inlet and outlet pipe, a water cooling device and a shearing stirrer, nitrogen was introduced, and stirring was started; water cooling was performed, and 323.4g of methacrylic anhydride was added dropwise within 1 hour, maintaining the temperature not exceeding 40°C; 780g of itaconic acid was added, and 2560g of a 20wt% sodium hydroxide aqueous solution was added dropwise to the reactor within 1 hour, maintaining the temperature not exceeding 50°C; the temperature was lowered to 0°C, 15.0g of potassium persulfate and 6.0g of sodium bisulfite were added in sequence, and stirred until completely dissolved; the temperature was raised to 60°C within 0.5 hour, the nitrogen was stopped, the stirring was stopped, and the reaction was kept warm for 6 hours; the temperature was lowered, the shearing stirrer was turned on to cut the material into gel particles, the material was discharged, and it was dried at 150°C to a water content of ≤0.2%, and a bio-based super absorbent resin was obtained, and the pure water absorption rate was 188.

[0042] Example 3

[0043] 262g of leucine, 131g of isoleucine, 7.3g of lysine and 2000g of water were added to a reactor equipped with a thermometer, a nitrogen inlet and outlet pipe, a water cooling device and a shear stirrer, nitrogen was introduced, and stirring was started; water was cooled, and 477.4g of methacrylic anhydride was added dropwise within 1 hour, maintaining the temperature not exceeding 40°C; then 390g of itaconic acid, 77.4g of methacrylic acid and 2000g of water were added, and 1148g of 25% sodium hydroxide aqueous solution was added dropwise to the reactor within 1 hour, maintaining the temperature not exceeding 50°C; the temperature was lowered to 15°C, and 3.3g of 30% hydrogen peroxide and 4.0g sodium thiosulfate are stirred until completely dissolved; the temperature is raised to 100°C within 1 hour, the nitrogen is stopped, the stirring is stopped, and the reaction is kept warm for 2 hours; the temperature is lowered, and the shear agitator is turned on to cut the material into gel particles, the material is released, and dried at 150°C to a moisture content of ≤0.2% to obtain a bio-based super absorbent resin with a pure water absorption rate of 225.

[0044] Example 4

[0045] 147g of glutamic acid, 3.2g of nonanediamine, 1.7g of decanediamine and 600g of water were added to a reactor equipped with a thermometer, nitrogen inlet and outlet pipes, a water cooling device and a shear stirrer, nitrogen was introduced, and stirring was started; water was cooled, and 163.2g of methacrylic anhydride was added dropwise within 0.5 hours, maintaining the temperature not exceeding 40°C; 668.2g of itaconic acid, 240.8g of methacrylic acid and 2500g of water were added, and 823g of 51% sodium hydroxide aqueous solution was added dropwise to the reactor, and the temperature was maintained at no more than 50°C; the temperature was lowered to 20°C, and 9.0g sodium persulfate and 5.0g glucose were added in sequence, and stirred until completely dissolved; the temperature was raised to 75°C within 0.5 hours, the nitrogen was stopped, the stirring was stopped, and the reaction was kept warm for 4 hours; the temperature was lowered, and the shear agitator was turned on to cut the material into gel particles, the material was discharged, and it was dried at 150°C to a water content of ≤0.2%, and a bio-based super absorbent resin was obtained, and the pure water absorption rate was: 257.

[0046] Example 5

[0047] 2.94 kg of glutamic acid, 31 g of pentamethylenediamine and 10.0 kg of water were added to a reactor equipped with a thermometer, a nitrogen inlet and outlet pipe, a water cooling device and a shearing stirrer, nitrogen was introduced, and stirring was started; water was passed for cooling, and 3.17 kg of methacrylic anhydride was added dropwise within 0.5 hours, maintaining the temperature not exceeding 40° C.; 5.20 kg of itaconic acid, 1.67 kg of methacrylic acid and 21.3 kg of water were added, and 14.0 kg of 32% sodium hydroxide aqueous solution was added dropwise to the reactor within 1 hour, maintaining the temperature not exceeding 50° C.; the temperature was lowered to 25° C., 50 g of potassium persulfate and 20 g of sodium sulfite were added in sequence, and stirred until completely dissolved; the temperature was raised to 90° C. within 1 hour, the nitrogen was stopped, the stirring was stopped, and the reaction was kept warm for 4 hours; the temperature was lowered, the shearing stirrer was turned on to cut the material into gel particles, the material was discharged, and it was dried at 150° C. to a water content of ≤0.2%, and a bio-based super absorbent resin was obtained, and the pure water absorption rate was 232.

[0048] Table 1 Performance parameters of bio-based super absorbent resins obtained in Examples 1 to 5

[0049] Pure water absorption Water absorption rate of saline solution Seawater absorption Example 1 211 45 20 Example 2 188 43 16 Example 3 225 49 20 Example 4 257 57 22 Example 5 232 48 23

Claims

1. A bio-based super absorbent resin, characterized in that: Its structural formula is shown in Formula I: In formula I, x=0.300~0.600, y=0.100~0.300, z=0.102~0.600, x+y+z=1, a=0.001~0.01, n=20~2000; R1=H, —CH3, —CH(CH3)2, —CH2CH(CH3)2, —CH(CH3)CH2CH3, —CH2CONH2, — CH2CH2CONH2, —CH2COOM, —CH2CH2COOM, At least one of; R2=—(CH2)5—,—(CH2)9—,—(CH2) 10 —, —(CH2) 13 — or —(CH2)4CH(COOM) — One less; M=H or Na, and the molar ratio of Na is 0.55~0.

80.

2. The method for preparing the bio-based super absorbent resin according to claim 1, characterized in that: The preparation method comprises the following steps: firstly reacting an amino acid, a diamino compound and methacrylic anhydride in water to obtain a mixed liquid; then adding itaconic acid, sodium hydroxide and / or methacrylic acid and water to prepare a mixed reaction liquid; then subjecting the mixed reaction liquid to free radical polymerization under the action of an initiator to obtain a product; and finally drying the obtained product to obtain a bio-based highly absorbent resin.

3. The method for preparing a bio-based super absorbent resin according to claim 2, characterized in that: The proportion of each raw material is: 75-612 parts by weight of amino acid, 1.0-21.4 parts by weight of diamino compound, 200-5000 parts by weight of water, 157.1-492.8 parts by weight of methacrylic anhydride, 390-780 parts by weight of itaconic acid, 0-240.8 parts by weight of methacrylic acid, 561-2880 parts by weight of sodium hydroxide aqueous solution, 1.0-20.0 parts by weight of oxidant, and 1.0-15.0 parts by weight of reducing agent.

4. The method for preparing a bio-based super absorbent resin according to claim 2 or 3, characterized in that: The amino acid is selected from at least one of glycine, alanine, valine, leucine, isoleucine, asparagine, glutamine, aspartic acid, glutamic acid, phenylalanine and tryptophan.

5. The method for preparing a bio-based super absorbent resin according to claim 2 or 3, characterized in that: The diamino compound is selected from at least one of pentamethylenediamine, nonanediamine, decanediamine, tridecanediamine and lysine.

6. The method for preparing a bio-based super absorbent resin according to claim 2 or 3, characterized in that: The initiator is a redox initiator, comprising an oxidizing agent and a reducing agent.

7. The method for preparing a bio-based super absorbent resin according to claim 6, characterized in that: The oxidant is at least one of hydrogen peroxide, ammonium persulfate, potassium persulfate or sodium persulfate; The reducing agent is at least one of sodium sulfite, sodium bisulfite, sodium thiosulfate or glucose.

8. The method for preparing a bio-based super absorbent resin according to claim 2 or 3, characterized in that: The preparation method of the bio-based super absorbent resin comprises the following steps: (1) adding 75-612 parts by weight of amino acid, 1.0-21.4 parts by weight of diamino compound and 200-2000 parts by weight of water into a reaction kettle equipped with a thermometer, nitrogen inlet and outlet pipes, a water cooling device and a shear stirrer, introducing nitrogen and starting stirring; (2) cooling with water, adding 157.1 to 492.8 parts by weight of methacrylic anhydride dropwise over 0.5 to 1 hour, maintaining the temperature not exceeding 40° C.; (3) adding 390 to 780 parts by weight of itaconic acid, 0 to 240.8 parts by weight of methacrylic acid and 0 to 3000 parts by weight of water, and dripping 561 to 2880 parts by weight of a 20 to 51 wt% aqueous sodium hydroxide solution over 0.5 to 1 hour, while maintaining the temperature at no more than 50° C.; (4) cooling to 0-30° C., adding 1.0-20.0 parts by weight of an oxidant and 1.0-15.0 parts by weight of a reducing agent in sequence, and stirring until completely dissolved; heating to 60-100° C. within 0.5-1 hour, stopping nitrogen flow, stopping stirring, and keeping the temperature for reaction for 2-6 hours; (5) Cooling, turning on the shear mixer to cut the material into gel particles, releasing the material, and drying to obtain a bio-based super absorbent resin.

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