The preparation method of silicate/multifunctional organic alkoxy silane cross linked polyacrylate salt water-absorbing resin
Technical field
The present invention relates to a kind of synthetic method of polyacrylic absorbent resin, specifically relate to the preparation method of a kind of silicate/multifunctional organic alkoxy silane cross linked polyacrylate salt water-absorbing resin.
Background technology
Water-absorbing resin also claims super strength water absorbent, is the class new functional macromolecule material that nearly twenty or thirty developed rapidly over year.Because it has self tens of times and even thousands of times water-retaining capacity and the performance of pressurizeing and also not dewatering, and has therefore obtained using widely in industries such as farming, woods, health care, chemical industry, building materials.Wherein crosslinked salt polyacrylate class water-absorbing resin is owing to have non-toxic and safe, liquid absorbency rate height, good, a gel physical strength height of water retention property, and polymerization easily, and advantage such as comparatively cheap have become topmost commodity water-absorbing resin kind in the synthetic water-absorbing resin.
Water-absorbing resin is actually the cross-linked hydrophilic polymer.The linking agent of polyacrylic water-absorbing resin generally be can with the polyfunctional group organic compound of carboxyl reaction, as bisamide, polyvalent alcohol, unsaturated polyether, allyl ester class, urea ester class etc.; Or multivalent metal cation, as Ca
2+, Zn
2+, Fe
2+, Cu
2+Deng oxyhydroxide, oxide compound, inorganic salt and organic metal salt.The invention provides a kind of is the synthetic method of the polyacrylic water-absorbing resin of novel crosslinker with silicate or multifunctional organic alkoxy silane.By the pH value of the hierarchy of control, water glass or multifunctional organoalkoxysilane can be in solution a large amount of silanol of forming of hydrolysis.These silanols have than the reactive behavior higher with the methyl alcohol of its structural similitude (China Synthetic Rubber Industry 1998,21 (6): 365-368).Yin W.S., people such as Gu T.R. are verified, in polyacrylic acid and derivative system thereof, the silanol base can mutual polycondensation under the catalysis of acid, forms the aggregate of Si-O-Si network structure, and part silanol base will connect that (Polymer 1997 with carboxylate radical (COOH) takes place that condensation reaction forms Si-O-C simultaneously, 38 (20), 5173-5178) (Journal of Applied PolymerScience 1997,64 (5), 903-909).In reaction system of the present invention, vinylformic acid is partly neutralized, system still is slightly acidic, the silanol base that silicate or multifunctional organic alkoxy silane form is under the catalysis of acid, on the one hand from polycondensation, connecting of condensation reaction formation Si-O-C will take place with carboxylate radical (COOH) in part silanol base simultaneously, thereby play crosslinked effect.Finally obtain having the polyacrylic acid water-absorbing resin of higher imbibition ability and big rate of liquid aspiration.(this achievement in research has been published in Journal of Applied Polymer Science 2004,91 (2), 936-940)
Because the Si-O-C link button has certain water-disintegrable, therefore with the water-absorbing resin of present method preparation after the imbibition swelling, have the water-absorbing resin more crosslinked than common linking agent faster degradation speed, generally in a couple of days to several months, can degrade fully.And the crosslinked water-absorbing resin of common linking agent experiences the several months usually even the several years all is difficult to degrade fully.
High-absorbent material is according to the difference of its purposes, and arranged different duration of service.For disposable goods, as medicated napkin, sanitary towel, nappy or diaper, incontinence sheet, hemostatic cotton etc., the product requirement absorption speed is fast, and water regain is big; Simultaneously, the general consumption of this series products is many, and discarded amount is big, must consider problem of environmental pollution, should use the water-absorbing material of easy degraded as far as possible.Water-absorbing resin of the present invention is highly suitable for these occasions, and it is the pick up height not only, and rate of liquid aspiration is fast, and the degraded easily of suction back, is the environment amenable water-absorbing material of a class.Studies have shown that, water-absorbing resin of the present invention also can be used as preserving moisture of cement-based material (as mortar, concrete etc.) and improves admixture (South China Science ﹠ Engineering University's journal (natural science edition) 2003,31 (11), the 41-44) (chemical building material 2004 of workability energy, (5), 53-56).
Summary of the invention
The object of the present invention is to provide the preparation method of a kind of silicate/multifunctional organic alkoxy silane cross linked polyacrylate salt water-absorbing resin, obtain a kind ofly after the imbibition swelling, having degradation speed faster, and have higher suction and inhale the silicate/multifunctional organic alkoxy silane cross linked polyacrylate salt water-absorbing resin of salts solution ability.
The preparation method of silicate of the present invention/multifunctional organic alkoxy silane cross linked polyacrylate salt water-absorbing resin comprises the steps:
(1) earlier vinylformic acid being mixed with to weight concentration is 40~70% the aqueous solution;
(2) in the monomer solution that step (1) is joined, add silicate or multifunctional organic alkoxy silane as linking agent, and in ice-water bath monomer solution to be neutralized to degree of neutralization with the alkali neutralizing agent be 60~90%; Silica-based and monomeric mol ratio is 0.02~0.25;
During as linking agent, linking agent and alkali neutralizing agent are mixed with mixing solutions with inorganic silicate, with in the above-mentioned mixing solutions and monomer solution, being neutralized to degree of neutralization is 60~90% in ice-water bath;
With multifunctional organic alkoxy silane during, then multifunctional organic alkoxy silane cross linked dose is added directly in ice-water bath that to be neutralized to degree of neutralization with the alkali neutralizing agent be in 60~90% the monomer solution as linking agent;
(3) initiator of adding monomer weight 0.01~0.5% in the monomer solution of (2) step gained; Be warming up to 60~80 ℃ of reactions, the reaction times is 0.5~2 hour;
(4) after the reaction product of step (3) the gained cooling, be placed in 80~150 ℃ the baking oven dryly, make pulverous water-absorbing resin through pulverizing again after the drying.
Above reaction system is the homopolymerization system.
The present invention can also in step (1) or at second kind of monomer of step (2) the back preceding adding of step (3), second kind of monomer and acrylic acid weight ratio be 5~50: 95~50;
Described second kind of monomer adjoins pyridine, dicarboxylic monomers or anhydrides monomer for acrylic monomer, ester class vinyl monomer, acrylamide monomers, nitrile vinyl monomer, vinyl alcohols monomer, vinyl alkyl ethers class monomer, vinyl pyrrole, the vinyl except that vinylformic acid.
At this moment reaction system is a copolymerization system.
No matter be the homopolymerization system in the present invention, or copolymerization system, the weight concentration of total monomer is 15~40% in the reaction system.
The described alkali neutralizing agent of step (2) is sodium hydroxide, potassium hydroxide, yellow soda ash, sodium bicarbonate or ammoniacal liquor.
The described linking agent of step (2) is an inorganic silicate.
The described linking agent of step (2) is two functional groups and above organoalkoxysilane.
The described initiator of step (3) is persulphate, hydrogen peroxide or redox initiator.
The used initiator of the present invention is persulphate, hydrogen peroxide or redox initiator, as Potassium Persulphate, ammonium persulphate, hydrogen peroxide, ceric nitrate salt, persulphate-sodium bisulfite, hydrogen peroxide-ferrous sulfate etc., its consumption accounts for 0.01~0.5% of monomer weight.
The used linking agent of the present invention is selected from inorganic silicate, as water glass, Starso, silicic acid sylvite etc.; Also can be selected from the two functional groups organoalkoxysilane of above (containing two functional groups), as dimethyldiethoxysilane, phenylbenzene diethoxy silane, phenyl triethoxysilane, aminopropyl triethoxysilane etc.
Compared with the prior art, beneficial effect of the present invention is as follows:
(1) is novel crosslinker with silicate or multifunctional organoalkoxysilane, made the ability that absorbs distilled water and physiological saline and can reach the above water-absorbing resin of 1200ml/g and 100ml/g respectively;
(2) water-absorbing resin with cross-linking method of the present invention preparation has degradation rate faster after the imbibition swelling, its complete degradation time be a couple of days to the several months, degradation rate depends primarily on the liquid absorption of water-absorbing resin and absorbs the type of liquid.Liquid absorption is big more, degrades soon more; The gel that absorbs distilled water gets soon than the gel degradation that absorbs salts solution; The gel that absorbs the univalent cation salts solution gets soon than the gel degradation that absorbs the polyvalent cation salts solution.Water-absorbing resin of the present invention is applicable to disposable uses such as medicated napkin, sanitary towel, nappy or diaper, incontinence sheet, hemostatic cotton, the big goods of many, the discarded amounts of consumption, is the environment amenable water-absorbing material of a class;
(3) water-absorbing resin of the present invention also can be used as preserving moisture of cement-based material (as mortar, concrete etc.) and improve workability can admixture.
Embodiment:
Embodiment 1
Take by weighing 100g vinylformic acid, use the 50g distilled water diluting, take by weighing the water glass (Na that accounts for vinylformic acid weight 10~25%
2SiO
39H
2O), for example, can select 10g, 15g, 20g, the water glass of 23g, water glass is dissolved among 40% the NaOH solution 110g, acrylic acid solution places the ice-water bath continuously stirring, above-mentioned mixed alkali liquor was added dropwise to acrylic acid solution continuously in 30 minutes neutralize, after the neutralizer cooling, add 0.01~0.5% Potassium Persulphate initiator that accounts for vinylformic acid weight, present embodiment is selected Potassium Persulphate 0.014g, 0.03g, 0.05g, 0.09g, 0.15g, after stirring question response solution is moved in the reaction vessel, be warming up to 60~80 ℃ and cause the aqueous phase solution reaction, as 65 ℃, 70 ℃, 75 ℃, 80 ℃, 0.5~2 hour reaction times, present embodiment selects 0.5,0.75,1.0,1.25,1.5 hour, after the product cooling, be placed in 100~120 ℃ the baking oven dryly, make pulverous water-absorbing resin through pulverizing again after the drying.
Embodiment 2
Take by weighing 100g vinylformic acid, use the 50g distilled water diluting, acrylic acid solution places the ice-water bath continuously stirring, in 30 minutes the NaOH solution of 110g 40% being added dropwise to acrylic acid solution continuously neutralizes, after the neutralizer cooling, be added dropwise to silica-based and acrylic acid mol ratio while stirring and be 0.02~0.25 multifunctional organic alkoxy silane, as dimethyldiethoxysilane, the phenylbenzene diethoxy silane, phenyl triethoxysilane, aminopropyl triethoxysilane etc., it is 0.04 that present embodiment is selected silica-based content and acrylic acid mol ratio of multifunctional organic alkoxy silane, 0.06,0.08,0.10,0.12,0.14,0.16,0.18, add 0.01~0.5% the Potassium Persulphate initiator account for vinylformic acid weight, present embodiment is selected Potassium Persulphate 0.014g, 0.03g, 0.05g, 0.09g, 0.15g, after stirring question response solution is moved in the reaction vessel, be warming up to 60~80 ℃ and cause the aqueous phase solution reaction, as 60 ℃, 65 ℃, 70 ℃, 75 ℃, 0.5~2 hour reaction times, present embodiment selects 0.5,0.75,1.0,1.25,1.5 hour, after the product cooling, be placed in 100~120 ℃ the baking oven dryly, make pulverous water-absorbing resin through pulverizing again after the drying.
Embodiment 3
Take by weighing 70g vinylformic acid, use the 73g distilled water diluting, take by weighing 14g water glass (Na
2SiO
39H
2O), water glass is dissolved among 40% the NaOH solution 78g, acrylic acid solution places the ice-water bath continuously stirring, above-mentioned mixed alkali liquor was added dropwise to acrylic acid solution continuously in 30 minutes neutralize, after the neutralizer cooling, add the dissolving of 30g acrylamide, add 0.03g Potassium Persulphate initiator, after stirring question response solution is moved in the reaction vessel, be warming up to 75 ℃ of reactions, 1.5 hours reaction times, was placed in 100~120 ℃ the baking oven dryly at product cooling back, made pulverous water-absorbing resin through pulverizing again after the drying.
Embodiment 4
Take by weighing 70g vinylformic acid, use the 73g distilled water diluting, acrylic acid solution places the ice-water bath continuously stirring, in 30 minutes the NaOH solution of 78g 40% being added dropwise to acrylic acid solution continuously neutralizes, after the neutralizer cooling, be added dropwise to aminopropyl triethoxysilane 20g while stirring, add the dissolving of 30g acrylamide, add 0.03g Potassium Persulphate initiator, after stirring question response solution is moved in the reaction vessel, be warming up to 70 ℃ of reactions, 1.5 hours reaction times, after the product cooling, be placed in 100~120 ℃ the baking oven dryly, make pulverous water-absorbing resin through pulverizing again after the drying.