TW201024358A - Production efficiency of superabsorbent polymer - Google Patents

Abstract

This invention relates to particulate water-absorbent resin particles which are modified by treating a surface cross-linking agent coated on to the particles by mixing the resin with the cross-linking agent in the mixer. These water-absorbent resin particles provide better performances of high absorption under load and high absorption capacity.

Description

201024358 VI. Description of the invention: [Technical field of invention], or water absorption of outer layer waterproof coated disposable wipes in cable. The present invention relates to water retaining agents and constructions widely used in agriculture or horticulture. Anti-dew beading agent for material p and materials for removing moisture from petroleum and sanitary articles such as diapers, feminine hygiene products, and methods for their manufacture. [Prior Art] A component material of a south water-absorbent resin which is known in the art of the art is a hydrolyzed stardiacrylonitrile graft polymer (Japanese Patent Publication No. 49 (1974)-43,395 'Zhonghe Temple Powder-Acrylic Graft Polymer (Japanese Patent Publication No. 88 (1976)-125,468) 'Saponified ethylene acetate-propylene ester copolymer (Japanese Patent Publication No. 52 (1977)-14, 689) A hydrolyzed acrylonitrile copolymer or a acrylamide copolymer (Japanese Patent Publication No. Sho 53 (1978)-15,959)' and a partially neutralized polyacrylic acid (Japanese Patent Laid-Open Publication No. 55 (1980)-84,304) and the like. Among them, the starch-acrylonitrile graft polymer contains a natural molecule-starch, which causes decomposition of rot, so it cannot be preserved for a long time; furthermore, its method is very complicated, so today's superabsorbent resin The preparation method is the most economical by using the superabsorbent resin obtained by crosslinking polymerization using acrylic acid and φ acrylate. The reason is that the raw material of the acrylate copolymer, acrylic acid, can be quickly purchased from the market, and the obtained super absorbent resin has high water absorption capacity, and has low manufacturing cost and most economical efficiency and does not cause rot. Decomposition is the most common superabsorbent resin. A method of polymerizing acrylic acid and propionate to form a superabsorbent resin can be obtained by several known methods, such as aqueous solution polymerization, reverse phase suspension polymerization, emulsion polymerization, or spraying or coating a monomer onto a fiber. A method such as polymerization on a substrate is carried out. In these methods, 'reverse phase suspension polymerization and ritual polymerization must use organic solvents, but if the temperature at the time of polymerization cannot be effectively controlled, the organic solvent will cause the temperature and pressure of the reaction system to increase. The fire phenomenon even caused an explosion, which threatened the safety of the personnel on the operation site and caused the environmental pollution to be ugly. The thief also had organic solvents. In addition, the water-absorbing resin liquid permeability has been paid more and more attention. Nowadays, the water absorption of the material of the diaper, sanitary napkin or the like is as well as the water-absorbing tree vinegar, the hydrophilic fiber and the like. The proportion of the water absorption meter that she made into the tree towel has a tendency to rise. The water-absorbent material that has not been used today has gradually reduced the amount of fiber, and the low-density hydrophilic fiber is used to gather paper. At the same time, hygienic products gradually include a higher proportion of water absorption, and a thinner sanitary buckle is not affected. Generally speaking, the water-absorbent tree g is in the shape of a particle, and the liquid is less permeable. · The life-month t* is the transmission capacity of the liquid, and indicates that after the liquid penetrates into the water-absorbing property, the particle 卩 or 卩, The water absorption is caused to swell. In the gel of the water-absorbing tree vinegar after the inflation is allowed to run, the capillary transfer is too slow due to the instability of the rotation, which is not conducive to the transport of the liquid. In general, the water-absorbing tree vinegar powder will be discolored (yellow and brown) due to the cleavage of the water-absorbing tree. What's more, in tropical or subtropical countries, the color change (yellow and color) of the water-moistened water-absorbing tree vinegar powder is accelerated (about four

Until June), the time to maintain the water-absorbent tree_storage aging and extension (four) color has become a goal that today's industry should strive to overcome. The water-absorbent tree _ (4) does not change much in its materiality, but it directly affects the perception of consumers after the production of nine-products. The water-repellent fineness of discoloration will make the user feel the contaminated sanitary products' and thus affect the reputation of the sanitary product manufacturer. Therefore, 'the water-absorbent product in the water-repellent fine 1 will greatly reduce its price as the commodity of the eight solution spears' JA+05-086251 thinks that one of the factors is in the water-soluble resin cracks' therefore recommended, over time The problem of coloring can be solved by using 2 other to remove the transition metal. For the coloring evaluation method, refer to Japanese Catalyst China Patent No. 991_. No. 3, and put the water-absorbing fine powder on the 6 U. lG. 63w__ plus the water-reducing tree §, _ chromatic change after week can be suppressed by 201024358 12.4-13.0, there is a certain effect. However, the addition of an organophosphate compound complicates the manufacturing process and has a lack of safety issues. SUMMARY OF THE INVENTION The superabsorbent resin is produced by initiating a radical polymerization reaction, and the acid group-containing monomer having an unsaturated double bond is required to use other water-soluble unsaturated double bonds in addition to acrylic acid. Monomers such as mercaptoacrylic acid, marinic acid, fumaric acid, 2-propenylamine-2-mercaptopropanesulfonic acid and the like. The monomer may be used in a single type, and may be used in combination with a plurality of monomers. Optionally, other hydrophilic monomers having an unsaturated double bond, such as acrylamide, mercaptopropionamide, may be added. 2-hydrocarbyl ethyl acrylate, 2-hydrocarbyl ethyl methacrylate, methyl acrylate, ethyl acrylate, dimethylamine propylene decylamine, gasified acrylamide, triterpene, etc. (US Patent 4, 057) , Nos. 521, 4, 062, 817, 4, 525, 527, 4, 286, 082 and 4,295, 987), but the addition amount is based on the principle of not impairing the physical properties of the superabsorbent resin. Before the radical polymerization reaction, the concentration of the aqueous monomer solution is preferably controlled between 20% by weight and 55% by weight, the appropriate concentration is between 30% and 45% by weight, and the concentration is less than 20% by weight. Recorded and silky * occupational machinery processing, the added concentration is more than 55wt% of the weight of the heavy sputum, too close to the saturation concentration, there is a problem that is difficult to adjust and the reaction φ is too fast, too much reaction heat is difficult to control. The silk of the acid-containing monomer should be partially neutralized to control the pH of the finished product to make it neutral or slightly acidic: the neutralizing agent is the oxychloride or carbonic acid compound of the gold or soil test group in the periodic table. For example, Hydroxide #9 potassium hydroxide, sodium carbonate, carbonic acid unloading, sodium hydrogencarbonate, carbonation gas or gas compound; neutralizing agent may be used alone or in combination. The silk fraction of the acid-containing monomer neutralized into a squid potassium sputum, and the concentration of the t and the concentration material was 45 m. Run 85%, preferably 50 secrets to 75 mol%. When the concentration of neutralization concentration is below 45m〇i%, the value of the finished product will be low. The percentage of the concentration of the neutralization concentration is higher than that of the finished product. The pH value of the finished product will be higher, and the pH value of the finished product is not neutral or slightly acidic. When it is inadvertently in contact with the human body, it is not suitable, and it is less safe than 201024358. The aqueous monomer solution may also be added with a water-soluble polymer compound to reduce the cost before the radical polymerization reaction, such as partially saponified or fully saponified polyethylene glycol, polyethylene glycol, polypropylene. ; fep acid, polypropylene, amine powder, temple powder or temple powder derivatives such as cellulose, cellulose methyl cellulose, ethyl cellulose and other polymers. The molecular weight of the water-soluble polymer compound is not particularly limited, and among them, a preferred water-soluble polymer compound is used alone or in combination of starch, partially saponified or fully saponified polyethylene yeast. The superabsorbent resin containing such a water-soluble polymer compound in an appropriate weight percentage is from 〇 to 2%, but preferably from 〇 to 10 wt〇/〇❿, preferably from 〇 to 5% by weight, and when added by more than 20% by weight, Affecting physical properties, making physical properties worse. The radical polymerization crosslinking agent should be added to the unreacted monomer solution before the radical polymerization reaction. The radical polymerization crosslinking agent can be selected from compounds having two or more unsaturated double bonds, such as N,N'-bis(2-propenyl)amine, N,N,-methine bis acrylamide, N,N,_ decyl bis methacrylamide, propyl acrylate, B Glycol dipropionate, polyethylene glycol diacrylate, ethylene glycol dimercapto acrylate, polyethylene glycol dimethacrylate, glycerol triacrylate, glycerol trimethacrylate, glycerin additional ring Ethylene oxide triacrylate or tridecyl acrylate, triterpene propylene, epoxidized triacetate or tridecyl acrylate, tris- propyl alcohol tridecyl Acrylate, trimethyl propylene triacrylate, N, N, N-tris(2-propenyl)amine, ethylene glycol diacrylate, polyoxyethylene glyceryl triacrylate, diethyl polyoxylate Ethylene glyceride, dipropylene triethylene glycol ester, etc., or compounds having two or more epoxy groups, such as sorbitol polycondensate Ethers, polyglycerol polyglycidol puzzle, ethylene glycol diglycidyl ether, diethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, glycerol polyglycidyl bis glycidyl ether and the like. After the radical reaction, the superabsorbent resin can have an appropriate degree of crosslinking to impart appropriate workability to the superabsorbent resin colloid. The above-mentioned radical polymerization crosslinking agent may be used singly or in combination of two or more. The amount of the appropriate additive of the radical polymerization crosslinking agent is from 0.001% by weight to 5% by weight. Between (based on the total solids of the reactants), a more appropriate amount of 201024358 is between G.Glwt% and 3% by weight. The addition of the seam is in the weight percentage of lwt%a, the hydrogel after polymerization is too soft and somewhat unfavorable for mechanical processing, and the amount of the additive is too low in water absorption of 5 wt% or more to lower the resin property. The polymerization begins with the decomposition of the free radical polymerization initiator to generate free radicals. The free radical initiator may be selected from a thermal decomposition type initiator, and the suitable thermal decomposition initiator may be a ruthenium compound such as hydrogen peroxide, mono-second butyl peroxide, guanidinium peroxide or persulfate. Salt (recording salt, metal salt), etc., and azo compounds such as 2.2,-azobis(2-amidinopropane) dihydrochloride, 22,_azobis(N,Nc) Dings) dihydrochloride; can also make the _ original agent into a redox type • starter, such as: acidic sulfite, thiosulfate, ascorbic acid or ferrous salt; or redox initiation The agent and the thermal decomposition type initiator are used in combination. First, the redox initiator starts to react to generate a radical. When the radical is transferred to the monomer, the polymerization is initiated. As the polymerization proceeds, a large amount of heat is released to raise the temperature, and when the temperature reaches the heat. When the decomposition temperature of the decomposition type initiator starts, the decomposition of the second stage thermal decomposition type initiator is caused, and the entire polymerization reaction is more complete. Generally, the radical polymerization initiator is suitably used in an amount of from 0.001 wt% to 1 wt% (based on the weight of the neutralized acrylate), and more suitably from 〇 iwt% to 5 wt%. When the weight percentage is below 〇.〇〇lwt%, the reaction is too slow to be economically effective. When the weight percentage is above 10% by weight, the reaction is too fast and the heat of reaction is not easily controlled. The production of polyacrylic superabsorbent resin, the polymerization reaction is generally carried out in a conventional batch reaction vessel or on a conveyor belt reactor, and the superabsorbent resin obtained by the reaction is first cut into a diameter of 20 mm by a mincer. The following small gels are preferably less than i〇mm in diameter and are then screened. The diameter of the gel having a fixed particle size is preferably 2.00 mm or less, preferably between 〇〇5 mm and 1.50 mm, and the gel having a particle diameter of more than 2.00 mm is returned to the mincer for re-shearing. When the gel body having a particle diameter of 0.03 mm or less is subjected to drying and pulverization treatment, it is easy to produce a high-yield product of 201024358 fine powder, and when the particle body having a particle diameter of 2. G0 mm or more is dried, the volume (4) is poor in heat conduction and causes rm. The residual monomer is biased, and the physical properties are not good. According to the present invention, the gamma-glycolate gel __ size distribution office does not make the _ county baking button performance to the best state, and for the time and temperature of the (iv) drying, after the screening is completed, the drying is performed. The drying temperature is 1 Torr. 〇: It is advisable to dry, and the dry temperature is below the dry time for too long. 'There is no economic benefit. The drying temperature is increased by the drying to make the cross-linking agent cross-link early, so that the subsequent (4) process towel The cross-linking degree is too high to remove the residual monomer, thereby reducing the residual monomer.

After drying, pulverization, screening and fixing the particle size, and then surface crosslinking agent coating treatment, the surface crosslinking agent may be a polyol such as: glycerol 'ethylene glycol, diethylene glycol, triethylene glycol , polyethylene glycol, propylene glycol, yeast! , 4_butanediol, trihydrocarbylmethylpropane, sorbitol, etc.; or a compound having two or more epoxy groups such as: mountain _ polycondensation ganolin, polyglycerol polycondensation _, Ethylene glycol dimethyl condensate _, diethylene glycol dimethyl condensate, polyethylene glycol dimerized glycine _, diglycerin polyglycidyl mouth; can also use alkylene carbonate age: ethylene glycol carbonate Base·1,3_: oxo-heterophenone 4, (d)-yloxy-oxo-indenyl, 4,Φ-dimethyl-dioxacyclopentane, 4-ethyl-^•dioxacyclo戍 明 明, Oxyheterocycle 2 _'4,6-monomethyl:: Dioxane H Houting - Oxygen Heterocycle - 2 Na. The appropriate amount of this cross-linking agent is between the weight percent 删. 魏 thief (based on the total solids of the reactants) ‘more appropriate amount between the tears (4). Cross-linking agent added __% Please _ Next day round _ Su, money agent added to the «% (four) Weng X, the financial property is too low, the performance of the fat. This month, when the surface of the k-water-absorbing tree _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ And the color does not change with time, and the multivalent metal ion water coated with the surface crosslinking agent is required to be controlled below __, which is preferably less than i_m, less than 10ppm. optimal. The polyvalent metal ion aqueous solution is an aqueous solution of titanium dioxide or ilmenite, titanium triethoxide, titanium lactic acid, lining, sulphate, alumina, and a plurality of miscible solutions. When the surface of the coating treatment is applied, the surface crosslinking agent is added in such a manner that it is directly added to the surface crosslinking agent according to the type of the surface crosslinking agent, or is added to the surface crosslinking agent aqueous solution, or the surface crosslinking agent is adjusted. The aqueous solution of the hydrophilic organic solvent is added, and a hydrophilic organic solvent such as methanol or B is preferred, and decyl alcohol and ethylene glycol are preferred. After the surface cross-linking agent coating treatment, the surface cross-linking ship is uniformly and silk-crosslinked by 8 (rc to electric _ heat treatment), and the cross-linking agent is cross-linked to achieve cross-linking reaction. The effect of the invention is that the heat treatment temperature is 8 (the crosslinking reaction time is less than rc for a long time, and there is no economical place, the heat treatment temperature is above the resin, the quality of the resin is transferred, and the heat treatment time is

It is advisable to use the surface treatment effect of 2 minutes to the time of the tempering, and the heat treatment temperature is adjusted according to the surface treatment effect to be obtained. The fox degree (7) is treated intermittently. When the heat treatment temperature is low, the occupation temperature is long. The water-absorbent resin of the present invention is obtained by the following method; (4) the water-soluble unsaturated acid-based monomer, the neutralization ratio is in the range of Μ to Μ mol%, and the concentration is in the range of 2G to Μ _ Reaction to form a gel; 201024358 (9) The gel is dried by a shoe to a temperature-heated hot air, pulverized, and a CUmm~0.85mm particle size powdery water-absorbent resin is selected; (c) a low-content polyvalent metal ion is added to the inorganic bribe The end surface cross-linking agent is coated; after (d) is characterized by (4) to 2 pits plus silk noodles, the multivalent metal ion compound inorganic salt powder added in the β method is selected from the group consisting of dioxins or The additives of the iron ore, triethanol chin, titanium lactic acid, lactic acid amine, sulphate, oxidized, and multi-component aqueous solutions must be controlled below 500 Å, and lOppra is the best. According to the method of the above-mentioned method, the water absorbing property is removed, which is miscellaneous (four) and does not have a problem of coloring with an increase in time. In order to demonstrate the good anti-staining ability of the water-absorbent resin of the present invention, the present invention is slightly modified by the method described on page 27 of the specification of Chinese Patent No. 99103660.3; the water-absorbing tree of 3._g is brewed (the dry powder of the granules) Tiled to the bottom of the glass culture dish, the container is 55 rounds and 25 inches high. And in the case of no cover, put in the 惶 怪 湿 wet box (four) ν XIANG C. · The LTD. AJH, :) keeps the water-absorbing tree vinegar powder in a two-week environment. Two weeks later, all the water-absorbing tree vinegar in the container was sedimented by a spectral color difference meter (10) to the surface of the water-based resin, and the yellowing index (%) was calculated. Yellowing index (%) = (chromaticity exposed to full temperature) / (chromaticity before exposure) χ 1 穿 The liquid permeability mentioned in this month is referred to Japanese Special Kaiping 9_5〇9591 The device described in the bulletin 'should absorb the water absorption fineness 〇.9〇0§ evenly into the cylinder with the bottom of the screen. In the artificial urine 10 201024358 column pressure, the pressure absorption - hour. The _% saline solution was passed through a round gel layer under a constant water M. The wear-in-test is in the room (four) _25 over-flat, as a function of time, with 20 seconds between the machine and the liquid-penetrating unit is 1 () · 7 · cm3 . s . g.i. V read the amount of liquid passing through the gel layer, set, butterfly, thin shirt _ force 贞: 2_2) to measure (four) i. will be according to the European patent G339461 A description of the seventh page described on the seventh page to 20, / The ( (4) water-based resin is placed in the cylinder at the bottom of the (4) net, the powder = r force, and then the bottle clear chest pottery _ « on, let this high suction, monthly selection of G. 9% of the chlorination solution „_ hours Then, the measured water absorption weight is divided by the weight of the water-absorbent resin, that is, the pressure-absorbing weight value is obtained. The retention force of the present invention is determined by the tea bag test method and the ancient value and the most healthy are removed by five measurement results. After taking the average value; 0.2g of high water absorption is placed in a tea bag, and soaking 0.9% of the aqueous sodium carbonate solution for 20 minutes, then placing the soaked tea bag in a centrifuge (diameter 23cm, speed just (four) The towel is centrifuged, three minutes later (four). The obtained value is first subtracted from the unfilled superabsorbent tree |_ the empty tea bag weight (8) and the same step operation) and then divided by the polymer weight to obtain the retention value. φ [Embodiment] The invention is illustrated by the examples, but the technical and patent scope of the invention is not limited by the examples. The inorganic salt used in the examples of the present invention is; the inorganic salt aqueous solution A: a commercially available poly-alloyed aluminum aqueous solution (polymerization international manufacturing H〇pax chemicals MFG. Co., Ltd. » PCA600) > ICP- The concentration of iron ions measured by MS (Inductively Coupled Plasma Mass Spectrometry) was 〇.〇2 ppm. Inorganic saline solution B: Commercially available multi-component aluminum solution (Popal chemicals MFG. Co., Ltd. > PC A300) &gt ; ICP-MS (Inductively Coupled Plasma 11 201024358

Mass Spectrometry) The concentration of iron ions was determined to be ppm 5 ppm 〇 Inorganic salt powder C: Commercially available sulfuric acid powder (Chinta Chemicals. 壹 grade.), and the concentration of iron ions was determined by ICP-MS to be 15 ppm. Inorganic salt powder D: Commercially available titanium dioxide powder, the concentration of iron ions was determined to be 1.2 ppm by ICP_MS. Example 1: ❹ 1) Take 48. /. 218.7 g of an aqueous solution of sodium cerium oxide was slowly added to a 2500 c.c conical flask of 27 gram g of acrylic acid and 291 known water. The dropping ratio of sodium hydroxide/acrylic acid was in the range of 0.85 to 0.95, and the dropping time was 2 hours, and was maintained. The temperature of the neutralization reaction system in the bottle was in the range of 汕 to 艽 ;; at this time, a monomer concentration of 42 wt ° / 〇 aqueous solution was obtained, wherein 7 〇 mol% (mole ratio) of the acrylic acid was partially neutralized to sodium acrylate. 2) Add 0.414 g of N,N,-decyl bis acrylamide to the water-soluble unsaturated monomer solution and maintain the temperature at about 20 °C. ❹ 3) Add 0. 144 δ hydrogen peroxide, 1.8 g of sodium hydrogen sulfite and 1.8 g of persulfate to start the reaction, and the anti-friction time is 25 minutes. 4) The gel formed after the reaction was chopped by a cutter mill, and a gel having a particle size of 2 mm or less was selected. 5) After drying at 130 °C for 2 hours, the sieve was used to screen a two-water-absorbent resin having a fixed particle size of 〇.imm~〇.85 mm. 6) Take this super absorbent resin i〇〇g, add 4.16g of ethylene carbonate carbonate / water / methanol / inorganic salt solution a = 1 / 1 / 1 / 0.6 (weight ratio) solution, 200 ° C The temperature is heat treated for 15 minutes, and after cooling, '12 201024358 is a high performance superabsorbent resin. The retention was determined to be 2645 g/g, the water absorption ratio under pressure of 2〇g/cm2 was 29.62 g/g, the liquid permeability was 61.52, and the yellowing index was 98 25%. Example 2: Repeat Example - 'Use only the inorganic salt aqueous solution A (U8 weight ratio) to replace the methanol/inorganic salt aqueous solution A of the step 6, and add ferric chloride _ 〇〇 lg, and determine the iron ion rolling degree to 1 2 via Icp_Ms. .35 ppm, the remaining steps were the same as in Experimental Example 1, and the reaction time was % minutes. The retention was determined to be 23.39 g/g, the water absorption ratio at 29 Torr was 29 勉, the liquid permeability was 1 〇 5 38, and the yellowing index was 96.51%. m Example 3: Repeat Example - with the addition of 5.00 (by weight) inorganic salt powder D, in place of the example - step 6 (4) / subtraction of A, _ Icp trap concentration of 5.87pPm, the remaining steps The same experimental example - the reaction time is % minutes. The retention strength was 22.42 g/g ′ at a pressure of 20 g/cm 2 and the water absorption ratio was 23 26 g/g, the liquid permeability was 2ΐ6·85, and the yellowing index was 99.68%.实施 Example 4: Repeat Example 3, adding 6.25 (by weight) aqueous solution of inorganic salt and mixing, replacing the inorganic salt, 11CP-MS', the cerium ion concentration is 0.68ppm, and the rest of the steps are the same as the experimental time. For 28 * - 'the gorge retention force is (1) she, the water absorption rate under pressure is 24.73g / g, the liquid permeability is 159·6, and the yellowing index is 9519%. . Example 5: Repeating Example 3 'mixed with 8.50 (by weight) inorganic salt powder c, replacing inorganic salt powder 201024358 terminal D 'determined iron ion concentration by ICP-MS was 2〇95 ppm, and the remaining steps were the same as experimental example 1. The reaction time was 28 minutes, the holding power was 22.95 g/g, the water absorption ratio was 23.68 g/g under the pressure of 2〇g/cm2, the liquid permeability was 189.66, and the yellowing index was 92 62〇/0. Comparative Example 1: By repeating Example 1, a 0.80 (by weight) inorganic salt powder c was added, instead of the first step of Example 6, and 0.0031 g of gasified iron powder was added, and the iron ion concentration was determined to be 127.82 ppm by Icp_MS. After 35 minutes, the remaining steps were the same as in Experimental Example, and a highly water-absorbent resin was obtained. The retention was determined to be 26.5 g/g, the water absorption ratio at 25 g/cm2 was 25.91 g/g, and the liquid permeability was 65.64% for the female 85.64'.

W Comparative Example 2: Repeating Example 1, adding 1.52 (by weight) aqueous solution of inorganic salt A, replacing step 6 of Example 1, and adding iron chloride powder 〇. 25g ICP-MS to determine the iron ion concentration is 293.85 ppm 'reaction time 35 minutes, the remaining steps are the same as experimental one, then the superabsorbent resin can be obtained. The retention was determined to be 24.52 g/g, the water absorption ratio at 23 g/cm 2 was 23.85 g/g, the liquid permeability was 106.38, and the yellowing index was 58.28%. Comparative Example 3: Repeating Example 1, adding 5.86 (by weight) inorganic salt powder c, instead of the first step of Example 6, and adding iron chloride powder _035g, ICp_MS determination of iron ion concentration is about 85 Peng, reaction time For 35 minutes, the rest of the steps were the same as in the experimental example, and a super absorbent resin was obtained. The measurement retention was 23.51 g/g, the water absorption ratio under pressure of 20 g/cm2 was 24 75 g/g, and the liquid permeability was 125.6, and the yellowing index was 41.08%. Comparative Example 4: Repeated Example -, adding 8.95 (by weight) of inorganic salt powder D was mixed, instead of the first step 6' of Example 1, and adding G.()(K) 31g at the end of the system, Icp was defeated by iron Dish 62 Peng, 14 201024358 The reaction time is 40 minutes, and the rest of the steps are the same as in Experimental Example 1, and the superabsorbent resin can be obtained. The measurement was maintained at a pressure of 22.51 g/g '20 g/cm 2 under a pressure of 18.25 g/g, a liquid permeability of 183.52, and a yellowing index of 43.21%. [Simple diagram description] [Main component symbol description]

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Claims (1)

201024358 VII. Patent application scope: 1. A method for producing a water-absorbent resin, which comprises: (4) making the water-soluble unsaturated acid-based monomer' neutralization ratio 45 to 85 m. /. Within the range, the concentration of the aqueous solution of the unsaturated monomer is polymerized in a range of 20 to 55 parts by weight to form a gel; (b) the hydrogel is dried, pulverized, and screened by hot air at a temperature of rC to 180 °C. 〇 mm·0.85 mm particle size powdery water-absorbent resin; (c) Adding a surface cross-linking agent containing a low content of multivalent metal ion inorganic powder; after (d) heating at 80 ° C and 230 ° C The surface treatment is a feature of the method. 2. The method for producing a superabsorbent resin according to the above-mentioned claim, wherein the surface crosslinking agent is treated by adding a low content of an inorganic salt aqueous solution of a polyvalent metal ion, wherein The surface crosslinking agent is mixed with the inorganic salt polyvalent metal ion compound, and is mixed with the superabsorbent resin in the form of an aqueous solution. The method for producing the super absorbent resin according to the above application, the surface crosslinking The joint agent contains inorganic salt, and the money is mixed with the weight of GQlwt%. The method for producing a super absorbent resin according to the invention of claim i, wherein the inorganic salt polyvalent metal ion compound aqueous solution has an iron ion concentration of less than 5 〇〇 ppm. 5. The method for producing a high-yield resin according to the above-mentioned patent application, the high-absorbency resin having a liquid permeability of not less than 3 〇 (1〇·7 . cm 3 · s . g-&gt) ; ===== 16