CN102597082A - Color-stable superabsorber - Google Patents

Abstract

The invention relates to a superabsorber comprising at least one stabilizer against discoloration, selected from phenols, phosphonic acid (HP(O)(OH)2), phosphoric acid (H3PO3), and the salts and esters of said acids, having improved stability against discoloration during storage at elevated temperatures or elevated humidity.

Description

The super-absorbent of colour stable

The present invention relates to a kind of super-absorbent (superabsorbent), Its Preparation Method And Use of colour stable and comprise its hygienic articles.The sense of the super-absorbent of colour stable be under temperature that improves and atmospheric moisture in storage process---if variable color---super-absorbent of variable color on not half only.

Super-absorbent is known.For this type material, also generally use such as titles such as " high swollen polymer ", " hydrogel (also using usually) ", " forming the polymkeric substance of hydrogel ", " water absorbent polymer ", " forming the material of water absorbent gel ", " swelling resin ", " water-absorbing resins " with dried forms.Said material grafting (being total to) polymkeric substance, cross-linked cellulose ether or starch ethers on suitable grafting base of cross-linked hydrophilic polymer (especially (being total to) polymkeric substance of the hydrophilic monomer that gathers), a kind of or more kinds of hydrophilic monomer, cross-linked carboxymethyl cellulose, partial cross-linked polyalkylene oxide are arranged or in aqueous liquid swollen natural product (for example guar derivative), be the most general wherein based on the acrylic acid water absorbent polymer of part neutral.The salient features of super-absorbent is that it can absorb several times to the aqueous liquid of himself weight and even under certain pressure, also no longer discharge the ability of this liquid.Usually the super-absorbent that uses with the form of dried powder after it absorbs liquid, is transformed into gel, correspondingly, after it absorbs water, is transformed into hydrogel as a rule.Crosslinked is vital for synthetic super-absorbent, and is the important difference with the pure thickening material of routine, because it causes polymkeric substance water insoluble.Soluble substance can not be used as super-absorbent.Super-absorbent most important applications field is an absorbed body fluid at present.Super-absorbent for example is used for, and hippen, adult use health product with incontinence product or women.Other Application Areass for example have as the water-holding agent of commodity truck garden, as being used for fp retaining agent, being used for the liquid-absorbent of food product pack or being usually used in moisture absorption.

Super-absorbent can absorb several times and keep the water that the residence absorbs to the water of himself weight and under certain pressure.Generally speaking, the CRC of this type super-absorbent (" centrifugal retention volume ", testing method vide infra) is at least 5g/g, preferably 10g/g and more preferably 15g/g at least at least." super-absorbent " also can be the mixture of each different superabsorbent materials or only when it interacts, just presents the mixture of the component of excess of export absorption characteristic; Material is formed so important unlike ultra water absorption character here.

Ability (the reservation that its receptivity also has retaining liquid under pressure of being not only that super-absorbent is overstated and wanted; Usually be expressed as " absorption under load " (AUL) or " absorption under pressure " (AAP); Testing method vide infra) and the liquid conductive ((SFC), testing method vide infra to be expressed as " salt solution water conservancy diversion rate " usually) of solvent swelling state.Compare with swollen super-absorbent not, swell gel can stop or prevent liquid conductive (" gel blocking ").The hydrogel that for example has a high-gel strength at solvent swelling state has liquid conductive characteristic preferably.The gel that only has low gel strength will be out of shape down in exert pressure (body pressure), thereby stop up the hole of super-absorbent/cellulosic fibre cartridge and stop further liquid-absorbent.The gel-strength that increases realizes through higher degree of crosslinking usually, yet higher degree of crosslinking can reduce the receptivity of product.A kind of method that increases gel-strength cleverly is to compare the degree of crosslinking that increases the particle surface place with the inside of superabsorbent particles.For this reason, it is other crosslinked superabsorbent particles dry and that have an average cross-linking density in the cross-linking step to be carried out in the thin upper layer of this particulate.Cross-linking density behind this surface in the crosslinked increase superabsorbent particles shell, it is increased to higher level with the absorption under the stress under compression.When the receptivity of superabsorbent particles upper layer descended, its nuclear---because existence of flowing copolymer chain---have improved receptivity with the shell facies ratio, thereby said shell structure had been guaranteed improved liquid conductive, and gel blocking can not occurred.Also knownly obtain higher generally crosslinked super-absorbent, the degree of crosslinking of granule interior is compared and possibly reduced with the particulate shell subsequently.

The method for preparing super-absorbent also is known.---it is the most common on the market---prepares through acrylic acid radical polymerization in the presence of linking agent (" internal crosslinker ") based on acrylic acid super-absorbent, wherein vinylformic acid usually through adding alkali (being generally aqueous sodium hydroxide solution) before polymerization, after the polymerization or part part before polymerization after polymerization, be neutralized to a certain degree.The polymer gel that obtains is thus pulverized (according to employed polymerization reactor, it can carry out with polymerization simultaneously) and drying.The dried powder that obtains thus (" stock polymer ") is crosslinked after on the particulate surface through itself and other linking agent is reacted usually; Said other linking agents are organic crosslinking agent or polyvalent cation for example---for example aluminium (usually using with the form of Tai-Ace S 150)---or the two, to obtain comparing higher crosslinked upper layer with granule interior.

The problem of frequent appearance is variable color for super-absorbent, and it appears in the storage process under the atmospheric moisture of temperature or raising of raising.This type situation appears at super-absorbent usually when in the torrid zone or subtropics country, storing.Super-absorbent tends to flavescence under this type situation; Itself in addition can appear brown or even be almost black.The variable color of the super-absorbent powder that this reality is colourless is not attractive in appearance and do not expect that because especially this is a visible in required thin health product, the human consumer can refuse inaesthetic health product.Cause the reason of variable color also not clear fully, but as if the stablizer in the impurity in use, monomer or the neutralizing agent of active compound (for example polymeric residual monomer), some initiators, surface back linking agent or the employed monomer in action.

Fredric L.Buchholz and Andrew T.Graham (eds.) are at " Modern Superabsorbent Polymer Technology "; J.Wiley & Sons, New York, U.S.A./Wiley-VCH; Weinheim; Germany, 1997, provide super-absorbent, its performance among the ISBN 0-471-19411-5 and prepared the comprehensive review of the method for super-absorbent.Wherein also mentioning the ion crosslinking agent of known calcium ion as super-absorbent at the 2.7.2 joint, is the available linking agent but have only trivalent ion (for example aluminium).

WO 2005/073260 A1 discloses the situation for preparing super-absorbent for the polymerization through supersaturated solution, and sodium acrylate monomers can completely or partially use the salt such as vinylformic acid magnesium, calcium acrylate, vinylformic acid strontium or vinylformic acid barium to substitute.WO 2005/011860 is divided into different linking agent kinds with the known internal crosslinker that is used for super-absorbent, and wherein one type comprises multivalent metal cation.It is included as magnesium, calcium and the strontium of divalent cation, but overall preferred trivalent aluminium.

WO 2008/055856 A1 has instructed through adding phosphoric acid or phosphoric acid salt and has prevented by in preparation super-absorbent process, being used for the neutralize variable color of crossing the super-absorbent that high Fe content causes of acrylic acid sodium hydroxide solution of part.JP 05/,086 251 A have instructed use phosphoric acid derivatives or its salt---and 1-hydroxy ethylene-1 especially, 1-di 2 ethylhexyl phosphonic acid, ethylenediamine tetraacetic (methylene phosphonic acid), NSC 446 five (methylene phosphonic acid) or its alkali metal salts or ammonium salt---the stablizer as super-absorbent suppresses variable color.WO 03/,059 962 A1 or consanguinity patented claim US 2005/0085604A1 disclose in the arbitrary steps of super-absorbent preparation, use metal chelator and before the aqueous polymers drying, add reduction or oxygenant as the method that suppresses variable color.WO 03/,014 172 A2 relate to the super-absorbent that use is formed by high purity acrylic acid, said super-absorbent especially not aldehyde-containing type to prevent its variable color.WO 00/55245 A1 instructed through be used in the inorganic reducing agent that adds after the polymerization and randomly metal-salt (for example alkaline earth salt) handle the stabilising method that suppress the super-absorbent variable color.Said inorganic reducing agent is generally hypophosphite, phosphite, hydrosulphite or sulphite.Said metal-salt is generally colourless (" colourless " characteristic also simply is called " white " usually) phosphoric acid salt, acetate or lactic acid salt, but be not halogenide.According to the instruction of WO 20,06/,058 682,, dry and back crosslinking reaction can avoid the variable color of super-absorbent when carrying out in the atmosphere of basic oxygen-free oxidizing gases.

EP 505 163 A1 disclose the purposes that surfactant and the binding substances that adds to compound on two keys (for example do not replace or substituted alkyl-or aryl--sulfinic acid or its salt) are used for reducing the content of super-absorbent residual monomer.------the purposes of the content that or polyamino acid or its salt are used to reduce residual back, surface linking agent after crosslinked behind the surface---especially as back, surface linking agent epoxy compounds---that but do not comprise the salt of organic acid or-sulfinic acid that EP 668 080 A2 and EP 1,570 869 A1 that divide an application relate to organic acid (comprising-sulfinic acid).EP 386 897 A2, EP441 975 A1 and EP 605 215 A1 have instructed sulphite, hydrosulphite or thiosulphate to be used to reduce the purposes of polymeric residual monomer content.EP 1 645 596 A1 have instructed the stabilising method that suppress the super-absorbent variable color through interpolation inorganic salt, aminocarboxylic acid sequestrant and organic oxidation-resistant agent.Employed inorganic salt have sulphite, hydrosulphite, pyrosulfite, hyposulfite, trithionate, tetrathionate, thiosulphate or nitrite.EP 1 577 349A1 have instructed these salt to be used for the purposes of identical purpose, but remain below 1 ppm by weight with the iron level of the super-absorbent of its processing.

WO 2009/060062 or International Patent Application PCT/EP2009/059793 have formerly instructed and in super-absorbent, have added sulfinate derivant so that super-absorbent is stablized nondiscoloration.WO2008/092 842 A1 have instructed the basic salt that in super-absorbent, adds divalent metal, and one of reason is to increase the stability that suppresses variable color.WO 20,08/,092 843 A1 disclose the basic salt that uses carboxylate salt and/or trivalent metal cation for same purpose.WO 2005/054 356A1 has instructed sterically hindered phenol to substitute p methoxy phenol (" toluhydroquinone ", " MEHQ ") commonly used in the industry purposes as the stablizer that suppresses acroleic acid polymerization, and it has the advantage that reduces the polymkeric substance variable color.

---especially to the flavescence look in the storage process under the atmospheric moisture of temperature that improves and/or raising or turn brown---has the super-absorbent of better stability to an object of the present invention is to seek other super-absorbent or to variable color.If the generation variable color, it also should only weaken receptivity (being included under the pressure) and the ability of water conservancy diversion thereof of use properties, especially its convection cell of super-absorbent slightly.Likewise, other performances should not weakened, smell for example, and it possibly be a problem for the situation of the sulfur-bearing reductive agent under moisture exists; Or its free-flowing property, it possibly be a problem for the situation of adding sodium hypophosphite; Or dust formation, it possibly be a problem for the situation of adding insoluble calcium phosphate.Other purposes of the present invention have the method for this type of searching preparation super-absorbent and the purposes of said super-absorbent.

The super-absorbent of the stablizer of this purpose through comprising at least a inhibition variable color realizes that said stablizer is selected from phenol, (HP (O) (OH) for phosphonic acids ₂), phosphorous acid (H ₃PO ₃) and these sour salt and esters.Find to prepare the purposes of the method for said super-absorbent, said super-absorbent in addition and comprised hygienic articles of said super-absorbent and preparation method thereof.

Super-absorbent of the present invention demonstrates the stability of unexpectedly good inhibition variable color, and its use properties (for example CRC, AUL or SFC) does not receive obvious weakening.

According to the present invention, with the stablizer adding super-absorbent of at least a inhibition variable color.

This stablizer can add by arbitrary form.Usually preferably with mainly insoluble (predominantly undissolved) form adding." mainly insoluble " refer to usually at least 50 weight %, preferred at least 70 weight % and more preferably the stablizer of at least 90 weight % add-ons adding fashionable being insoluble in the solvent.For this reason, said stablizer is introduced with dried forms or with the form of suspensoid in the suspension medium as powder.

Said stablizer can add in the super-absorbent in the random time in the preparation process.Preferably add and be used for monomer polymerized mixture or adding monomer, but only exist the back to add, promptly not early than polymerization process at cross-linked polymer.It can be in polymerization process for example, in the cross-linking step process of back, surface or crosslinked back, back, surface adds.When stablizer adds monomer mixture or monomer, its can add additionally all under any circumstance that any inhibition is not expected or the stablizer of premature polymerization in.Especially when said stablizer is sterically hindered phenol, preferably it is no earlier than polymerization process and adds.

Said stablizer is solvable or insoluble.Said stablizer is preferably water insoluble, and promptly its solubleness in water under 25 ℃ is at most 5g/l, preferred 1g/l at the most.

Said stablizer (one or more) is selected from phenol, (HP (O) (OH) for phosphonic acids ₂), phosphorous acid (H ₃PO ₃) and these sour salt and esters.

In phenol, preferred sterically hindered phenol.The sense of sterically hindered phenol is at least on 2 of phenyl ring and optional also have substance or dual substitution in side chain base on 6 at the phenyl ring phenol of---preferred dual substitution in side chain base---.The sense of substitution in side chain base is: with atom that the phenyl ring of phenol links to each other on, except the carbon atom of coupled phenyl ring, also contain the substituting group of at least two non-hydrogen groups.Yet, sterically hindered phenol also have at least on 2 and optional also on 6, contain have space requirement unbranched substituent those.Its sense is such substituting group: its comprise at least 6, preferred at least 8 and more preferably at least 12 non-hydrogen atoms but with atom that the phenyl ring of phenol links to each other on, except the carbon atom of coupled phenyl ring, only contain a non-hydrogen group.The most simply the instance of substance substitution in side chain base has secondary alkyl (for example 2-propyl group, 2-butyl, 2-amyl group, 3-amyl group, ethylhexyl) or naphthenic base (for example cyclobutyl, cyclopentyl, cyclohexyl) or aryl (for example phenyl).The instance of the simplest dual substitution in side chain base has tertiary alkyl, for example the tertiary butyl, tert-pentyl or norcamphyl (norbornyl).The simplest unbranched examples of groups has hexyl, heptyl, octyl group, nonyl, decyl, undecyl and dodecyl, and neo-pentyl, new hexyl or dodecyl thiomethyl.Yet all these groups self also can be substituted or comprise the atom except carbon and hydrogen.The phenyl ring of phenol also can---except on 2 and randomly the substituting group on 6---randomly contain other substituting groups.The instance of preferred sterically hindered phenol has 2-tert.-butyl phenol, 2,6 di t butyl phenol, 2,6 di tert butyl 4 methyl phenol (to be also referred to as 2,6-di-t-butyl-p-Cresol or 3; 5-di-t-butyl 4-hydroxytoluene), 3, the ester that 5-di-t-butyl-4-hydroxyl phenylacetic acid, 3,5-di-t-butyl-4-hydroxy phenylpropionic acid and these acid and pure and mild polyvalent alcohol generate, for example itself and terepthaloyl moietie, glycerine, 1; 2-or 1, monoesters or polyester that ammediol, TriMethylolPropane(TMP) or tetramethylolmethane generate, for example tetramethylolmethane four (3-(3, the 5-di-tert-butyl-hydroxy phenyl) propionic ester) or 3; 5-di-tert-butyl-hydroxy phenyl propionic acid stearyl, 4,4-thiobis (the 6-tertiary butyl--cresols), 4, two (the dodecyl thiomethyl)-neighbour-cresols, 3 of 6-, 3 '; 3 ", 5,5 ', 5 "-six tertiary butyls-α; α ', α "-(1,3; 5-Three methyl Benzene-2,4,6-three bases) three-p-Cresol (2; 4,6-three [(4-hydroxyl-3,5-di-tert-butyl-phenyl) methyl] 1; 3, the another name of 5-Three methyl Benzene, CAS 1709-70-2; Can

1330 trade marks available from Ciba Specialty Chemicals, Basle, Switzerland AG), N; N-hexane-1,3-two bases two (3-(3,5-di-tert-butyl-hydroxy phenyl propionic acid amide)), 2; 2 '-ethylenebis [4,6-two (1, the 1-dimethyl ethyl) phenol] and ethylenebis (oxygen ethylidene) two-3-(5-tertiary butyl-4-hydroxy--tolyl) propionic ester) (CAS 36443-68-2; Can

245 trade marks available from Ciba Specialty Chemicals, Basle, Switzerland AG).

Other suitable stablizers of the present invention have phosphonic acids, and (HP (O) (OH) ₂) and phosphorous acid (H ₃PO ₃) salt and ester and phosphonic acids itself.Phosphonic acids and phosphorous acid are tautomers; The latter does not exist with the form of free acid.The real verivate of phosphorous acid has only its three ester, is commonly referred to phosphorous acid ester.Tautomeric phosphonic verivate is commonly referred to phosphonate.For example alkali-metal all primary-with secondary phosphine hydrochlorate---comprise primary of ammonium and earth alkali metal-and secondary phosphine hydrochlorate---all be suitable.Suitable instance comprises primary in addition-and/or the phosphonic acids aqueous solution and at least a cationic phosphonic acids aqueous solution that is selected from sodium, potassium, calcium, strontium of secondary phosphine acid ion.The suitable phosphorous acid ester or the instance of phosphonate have two [single ethyl (3,5-di-t-butyl-4-hydroxybenzene methyl) phosphonic acids] calcium, three (2, the 4-di-tert-butyl-phenyl) phosphorous acid esters, 3; Two (the octadecyl oxygen bases)-2 of 9-; 4,8,10-four oxa-s-3; 9-two phospha spiral shell [5.5] undecanes and two (2, the 4-di-tert-butyl-phenyl) pentaerythritol diphosphites.Stablizer can be phosphonate or phosphorous acid ester and sterically hindered phenol simultaneously.

If said stablizer is---insoluble---originally as particle; Therefore it mainly exists with form of powder in use.Median size is usually at least 0.001 μ m, preferred at least 0.002 μ m, more preferably at least 0.005 μ m and most preferably at least 0.01 μ m and 500 μ m, preferred 200 μ m at the most, more preferably 100 μ m and most preferably at the most in the scope of 50 μ m at the most at the most usually.Said particle itself can be the aggregate or the agglomerate of littler primary particle.Said particle diameter can be measured through screen analysis, but a kind of simpler and thereby preferable methods be to measure particle diameter through laser diffractometry.These methods be known and on the commercially available suitable apparatus that gets routine operation.

The add-on of the stablizer of aforementioned inhibition variable color---if interpolation---is generally at least 0.0001 weight %, preferably at least 0.001 weight % and more preferably at least 0.025 weight % separately; And 3 weight %, preferably 2 weight % and more preferably 0.5 weight % at the most at the most at the most usually are separately based on the gross weight meter of super-absorbent of the present invention.

According to the present invention, super-absorbent can mix with stablizer arbitrarily.Generally speaking, this type super-absorbent be grafting (being total to) polymkeric substance, cross-linked cellulose or starch ethers on suitable grafting base of cross-linked hydrophilic polymer (especially (being total to) polymkeric substance of polymerization hydrophilic monomer), a kind of or more kinds of hydrophilic monomer, cross-linked carboxymethyl cellulose, partial cross-linked polyalkylene oxide or can be in aqueous liquid swollen natural product (for example guar gum derivatives).Preferably use based on the acrylic acid super-absorbent of part neutral.The characteristic of super-absorbent especially is its absorption and keeps the fluidic ability.

The preferred super-absorbent of the present invention for example aqueous solution polymerization of the monomer mixture through comprising following material prepares

A) at least a contain at least one acidic group and the ethylenically unsaturated monomers that randomly exists with salt form at least in part,

B) at least a linking agent,

C) at least a initiator,

D) randomly a kind of or more kinds of can with a) in specified monomer copolymerization ethylenically unsaturated monomers and

E) randomly a kind of or more kinds of water-soluble polymerss.

Monomer is a) preferably water miscible, i.e. 1g/100g water, preferably 5g/100g water, more preferably 25g/100g water, the 35g/100g water at least most preferably at least at least at least usually of solubleness in water under 23 ℃.

Suitable monomers a) has, for example ethylenic unsaturated carboxylic acid or its salt, for example vinylformic acid, methylacrylic acid, toxilic acid or its salt, maleic anhydride and methylene-succinic acid or its salt.Preferred especially monomer has vinylformic acid and methylacrylic acid.Preferred very especially vinylformic acid.

Other suitable monomers a) have, for example ethylenic unsaturated sulfonic acid, for example styrene sulfonic acid and 2-acrylamido-2-methyl propane sulfonic acid (AMPS).

Impurity can have considerable influence to polymerization.Therefore employed raw material should have maximum purity.Therefore ad hoc the purifying monomer is a) normally favourable.Suitable purification process is set forth in for example WO 2002/055469 A1, WO 2003/078378 A1 and WO 2004/035514 A1.Suitable monomers a) has; For example; According to the vinylformic acid of WO 2004/035514 A1 purifying, it contains 99.8460 weight % vinylformic acid, 0.0950 weight % acetate, 0.0332 weight % water, 0.0203 weight % propionic acid, 0.0001 weight % furfural, 0.0001 weight % maleic anhydride, 0.0003 weight % diacrylate and 0.0050 weight % hydroquinone monomethyl ether.

Vinylformic acid and/or its salt monomer a) ratio in the total amount be preferably at least 50mol%, more preferably at least 90mol%, most preferably be 95mol% at least.

Monomer solution comprises preferred 250 ppm by weight at the most, preferred 130 ppm by weight at the most, more preferably 70 ppm by weight and preferred at least 10 ppm by weight, the more preferably quinhydrones monoether of at least 30 ppm by weight, especially about 50 ppm by weight at the most, a) counts based on unneutralized monomer separately;---being monomer salt a)---through the neutral monomer a) regards unneutralized monomer as based on computation purpose.For example, monomer solution can make through the ethylenically unsaturated monomers that use has an acidic group, and has the quinhydrones monoether of proper content.

Preferred quinhydrones monoether is hydroquinone monomethyl ether (MEHQ) and/or alpha-tocopherol (vitamin E).

Suitable crosslinking agent b) be to contain at least two compounds that are suitable for crosslinked group.This type group has, for example, and the ethylenic unsaturated group in free redical polymerization to the polymer chain and can form the functional group of covalent linkage with monomer acidic group a).In addition, can also be suitable as linking agent b with the polyvalent metal salt of monomer at least two acidic groups formation co-ordination bonds a)).

Linking agent b) is preferably the compound that contains the polymerizable groups at least two free redical polymerizations to the polymer network.Suitable crosslinking agent b) ethylene glycol dimethacrylate, diethylene glycol diacrylate, polyethyleneglycol diacrylate, allyl methacrylate(AMA), Viscoat 295, triallylamine, tetra allyl ammonium chloride, the tetraene propoxy-ethane that for example is set forth in EP 530 438 A1 is arranged; Be set forth in two of EP 547 847 A1, EP 559 476 A1, EP 632 068 A1, WO 93/21237 A1, WO 2003/104299 A1, WO 2003/104300 A1, WO 2003/104301 A1 and DE 103 31 450 A1-and triacrylate; Be set forth in the mixing propenoate that except acrylate group, also comprises other ethylenic unsaturated groups of DE 103 31 456 A1 and DE 103 55 401 A1, or for example be set forth in the linking agent mixture of DE 195 43 368 A1, DE 196 46 484 A1, WO 90/15830 A1 and WO 2002/32962 A2.

Preferred cross-linking agents b) be pentaerythritol triallyl ether, tetraene propoxy-ethane, methylene-bis USAF RH-1, the heavy ethoxylated trimethylolpropane triacrylate of 15-to 20-, the heavy ethoxylated glycerol base of 15-to 20-triacrylate, in molecular chain, contain 4 to 45-CH ₂CH ₂The unitary polyethyleneglycol diacrylate of O-, Viscoat 295 and triallylamine.

Very special preferred cross-linking agents b) polyethoxylated is arranged and/or gather propoxylated glycerol, it changes into two-or triacrylate with the acrylic or methacrylic acid esters, described in for example WO2003/104301 A1.Two of the heavy ethoxylated glycerol of 3-to 10-and/or triacrylate be particularly advantageous.Preferred very especially 1-to 5 is two-or triacrylate of ethoxylation and/or propoxylated glycerol heavily.The heavily triacrylate of ethoxylation and/or propoxylated glycerol, the especially triacrylate of 3 heavy ethoxylated glycerols of 3-to 5 most preferably.

Linking agent b) amount be preferably 0.05 to 1.5 weight %, more preferably 0.1 to 1 weight %, most preferably be 0.3 to 0.6 weight %, a) count based on monomer separately.Along with the raising of content of crosslinking agent, centrifugal retention volume (CRC) reduces, and the absorption value under the 0.3psi pressure (AUL0.3psi) improves.

Initiator c) can be all compounds that under polymerizing condition, produce radical, for example thermal initiator, redox initiator, photoinitiator.Suitable redox initiator has peroxo-two sodium sulfate/xitix, hydrogen peroxide/xitix, peroxo-two sodium sulfate/sodium sulfite anhy 96 and hydrogen peroxide/sodium sulfite anhy 96.The preferred mixture that uses thermal initiator and redox initiator, for example peroxo-two sodium sulfate/hydrogen peroxide/xitix.Yet employed reduction components is preferably sodium salt, the 2-hydroxyl-disodium salt of 2-sulfonic group acetate and the mixture of sodium sulfite anhy 96 (

FF6M or

FF7) of the 2-hydroxyl-2-sulfino acetate of hereinafter detailed description.

Can with a) the ethylenically unsaturated monomers d of copolymerization of the ethylenically unsaturated monomers that contains acidic group) have; For example, acrylic amide, USAF RH-1, Hydroxyethyl acrylate, Rocryl 400, dimethylaminoethyl acrylate methyl base ammonia ethyl ester, vinylformic acid dimethylamino ethyl ester, vinylformic acid dimethylamino propyl ester, vinylformic acid diethyl amino propyl ester, dimethylaminoethyl acrylate methyl base ammonia ethyl ester, methylacrylic acid diethyl amino ethyl ester, toxilic acid or its salt and maleic anhydride.

Employed water-soluble polymers e) can be Z 150PH, Vinylpyrrolidone polymer, starch, starch derivative, modified-cellulose (for example methylcellulose gum or Natvosol), gelatin, polyoxyethylene glycol or ROHM, preferred starch, starch derivative and modified-cellulose.

Usually use monomer solution.The water-content of monomer solution be preferably 40 to 75 weight %, more preferably 45 to 70 weight %, most preferably be 50 to 65 weight %.Also can use monomer suspension, promptly oversaturated monomer solution.Along with the raising of water-content, the energy requirement in subsequent drying increases; And along with the reduction of water-content, heat of polymerization only can be removed deficiently.

At least a water-soluble alkali earth metal salt that is selected from calcium, strontium and barium salt is randomly added in the super-absorbent of the present invention.Can use in the said element two kinds might make up or the mixture of the salt of whole three kinds of said elements.Aspect technique effect, there is not significant difference between calcium salt, strontium salt and the barium salt, be most preferred but start from the economic consideration calcium salt.Generally speaking, for the super-absorbent that comprises alkaline earth salt, the present invention suppress variable color stablizer requirement than the situation of alkali-free earth metal salt still less.

The negatively charged ion of alkaline earth salt can freely be selected in principle, and condition is that it can not produce detrimental action to super-absorbent and/or its purposes.The anionic instance of suitable alkaline earth salt has halogen ion (especially cl ions), hydroxide radical, carbonate, carboxylate radical (for example formate, acetate moiety, propionate or lactate), nitrate radical or sulfate radical.Also can use mixture.

Even preferred use the water-soluble alkali earth metal salt or those of reaction---they are less soluble in water rapidly with super-absorbent or monomeric acidic group.This type salt has---especially for routine prepare the situation of super-absorbent by the water-containing monomer mixture---can save the normal advantage of employed neutralizing agent originally.Negatively charged ion to alkaline earth salt is correspondingly selected; Preferred hydroxide radical, carbonate or lactate.

Preferred generally alkaline earth salt has calcium hydroxide, strontium hydroxide, hydrated barta, lime carbonate, Strontium carbonate powder, barium carbonate, lactic acid ca, strontium lactate, barium lactate, calcium sulfate, Strontium Sulphate, permanent white or its mixture.Special preferably calcium hydroxide, lime carbonate, lactic acid ca and calcium sulfate.

The add-on of said alkaline earth salt is generally at least 0.1 weight %, preferably at least 0.5 weight % and more preferably at least 1 weight %; And 20 weight %, preferably 10 weight % and more preferably 5 weight % at the most at the most at the most usually are separately based on the total amount meter of the ethylenically unsaturated monomers that contains at least one acidic group.It calculates with free acid; Any acidic group of neutral does not wholly or in part count in calculating.Some alkaline earth salts can comprise crystal water.It does not count in calculating yet.

Said alkaline earth salt (or mixture of alkaline earth salt) adds in the monomer mixture before polymerization or in the polymerization process; If or independent drying step is carried out in polymerization afterwards; Then before dry, add in the polymkeric substance, or a part before polymerization or in the polymerization process and a part before dry in the adding polymkeric substance.What expect is the uniform distribution of alkaline earth salt in super-absorbent.In principle, alkaline earth salt---aspect method and time---is as following said and sneak into to neutralizing agent.Also the simplest thereby preferable methods is before polymerization, to add in the monomer mixture.Yet alkaline earth salt also can be introduced in the formed polymer gel in polymerization process or after the polymerization, but under any circumstance all is before dry, to introduce.The adding of in polymerization process, carrying out simply mode is carried out, particularly for the situation of the polymeric material being carried out method of mixing, for example polymeric situation in kneader.The adding of carrying out after polymerization and before the drying simply mode is carried out; Particularly for the polymeric mixture is sent to the situation of the method for special drying step by polymerization procedure, i.e. the situation of polymerization and dry all methods of in independent device, carrying out especially.In this case, alkaline earth salt can be sneaked in the polymer gel through the blending means and the device of any known.

Said alkaline earth salt is as dry substance or as the solution in the solvent or dispersion-s and use.Employed solvent is preferably water.

For reaching the best use of, preferred stopper needs dissolved oxygen.Therefore, before polymerization, can make monomer solution not contain dissolved oxygen through inerting effect (promptly feed rare gas element, be preferably nitrogen or carbonic acid gas).Make the oxygen content of monomer solution preferably be reduced to before the polymerization, more preferably be low to moderate, most preferably be low to moderate less than 0.1 ppm by weight less than 0.5 ppm by weight less than 1 ppm by weight.

Monomer mixture can comprise other components.The instance of employed other components has for example sequestrant in this type of monomer mixture, so that metals ion is retained in the solution.

The acidic group of the polymer gel that is obtained by polymerization partly is neutralized usually.Neutralization is preferably carried out in monomer stage; In other words, contain the monomeric salt of acidic group or---(" acid of part neutral ") is used as component a) to the monomer that or rather---contains acidic group in polymerization with the mixture that contains the monomeric salt of acidic group.This is used for the monomer polymerized mixture or preferably sneaks into the monomer or its solution that contain acidic group and realize through the neutralizing agent of aqueous solution form or also preferred solid form is sneaked into usually.Degree of neutralization is preferably 25 to 95mol%, more preferably 50 to 80mol%, most preferably is 65 to 72mol%; Conventional neutralizing agent be can use for this reason, alkali metal hydroxide, alkalimetal oxide, alkaline carbonate or alkali metal hydrocarbonate and composition thereof are preferably.Also can use ammonium salt to replace an alkali metal salt.Preferred especially basic metal is sodium and potassium, but preferred very especially sodium hydroxide, yellow soda ash or sodium hydrogencarbonate and composition thereof.

Yet the polymer gel stage that also can form after polymerization, in polymerization neutralizes.Thereby also can be before polymerization through in monomer solution, add practically a part of neutralizing agent and only after polymerization, set required final degree of neutralization neutralization in polymer gel stage and be up to 40mol%, be preferably 10 to 30mol% and 15 to 25mol% acidic group more preferably.When polymer gel after polymerization by at least in part and the time, polymer gel is preferably carried out mechanical disintegration, for example pulverize through extrusion machine, in this case neutralizing agent sprayable, spray or topple on it and sneak into carefully then.For this reason, the gel piece that is obtained can push with homogenizing repeatedly.

Yet, preferably neutralize in monomer stage.In other words: at one very in the particularly preferred embodiment, employed monomer is 25 to 95mol%, more preferably 50 to 80mol%, more preferably 65 to 72mol% monomeric salt that contains acidic group and the monomeric mixture that contains acidic group that complements to the remainder of 100mol% a).This mixture is for example sodium acrylate and acrylic acid mixture or potassium acrylate and acrylic acid mixture.

In a preferred embodiment, the employed neutralizing agent that neutralizes is usually less than 10 ppm by weight, preferably is lower than 2 ppm by weight and more preferably less than the neutralizing agent of 1 ppm by weight for its iron level.Same expectation be the negatively charged ion of oxygen acid of cl ions and the chlorine of low levels.Suitable neutralizing agent has 50 weight % sodium hydroxide solution or the potassium hydroxide solutions of for example selling with " film rank (membrane grade) " usually, and purer and also suitable but also more expensive is 50 weight % sodium hydroxide solution or the potassium hydroxide solutions of selling with " amalgam rank (amalgam grade) " or " mercury method (mercury process) " usually.

Add therein in the of the present invention optional embodiment of alkaline earth salt; When though employed alkaline earth salt is the water-soluble alkali earth metal salt or is the lower but reaction of solubleness more rapidly during alkaline earth salt, can save the amount corresponding to the neutralizing agent of alkaline earth metal ion add-on.In other words, alkaline earth salt also can be used as neutralizing agent simultaneously, in the case the divalent alkaline-earth metal ion substitution two monovalent alkalimetal ions.The oxyhydroxide that earth alkali metal is especially arranged, carbonate and the lactic acid salt that are suitable for this purpose.

Method by preparing super-absorbent such as above those monomer mixtures through case description also is known.Suitable polymerization reactor has, for example, and knead reactor drum or belt reactor.Of WO 2001/38402 A1, in kneading machine, the polymer gel that monomer solution or suspension polymerization form is through for example pulverize changeing (contrarotatory) stirrer shaft continuously.With on polymerization be set forth in for example EP 955 086 A2, DE 38 25 366 A1 and US 6,241,928.As for example EP 445 619 A2 and DE 19 846 413 A1 are said; Polymerization in the belt reactor; Be similar in the same known batch operation or the polymerization in the tubular reactor, form polymer gel, it must be pulverized in other operation steps (like mincer, extrusion machine or kneading machine).Yet; Also can be as for example EP 457 660 A1 are said; Prepare spherical or difform superabsorbent particles through suspension polymerization or emulsion polymerization; Or of for example EP 348 180 A1, EP 816 383A1, WO 96/40427 A1, US 4 020 256, US 200,2/0 193 546 A1, DE 35 19 013A1, DE 10 2,005 044 035 A1, WO 2007/093531 A1, WO 20,08/,086 976 A1 or WO 2009/027356 A1, prepare spherical or difform superabsorbent particles through spray polymerization or dropping liquid polymerization (droplet polymerization).Also knownly wherein monomer mixture is applied to base material (for example non woven web (nonwoven web)) and carries out the polymeric method, of for example WO 02,/94 328 A2 and WO 02,/94 329 A1.

Then will by aqueous solution polymerization and randomly the polymer gel that obtains of subsequently neutralization preferably with the conveyor dryer drying up to residual regain be preferably 0.5 to 15 weight %, more preferably 1 to 10 weight %, most preferably be 2 to 8 weight % (the residual testing method that contains wet or water cut vide infra).Under the situation of residual excess moisture, through the second-order transition temperature T of exsiccant polymer gel _gCross lowly, possibly make it further to process difficultly.Under the low excessively situation of residual regain, too crisp through the exsiccant polymer gel, in pulverising step subsequently, obtain undesirable a large amount of polymer beads with small grain size (" fine powder ").Before dry the solid content of gel be generally 25 to 90 weight %, be preferably 30 to 80 weight %, more preferably 35 to 70 weight %, most preferably be 40 to 60 weight %.Yet, randomly, also can use fluid bed dryer or have the unitary Hot mixer (for example paddle dryer or have the similar drying machine of the mixing tool of different designs) that adds of mechanically mixing and carry out drying.Randomly, drying machine can be under nitrogen or another kind of non-oxide rare gas element or at least in the following operation of oxygen partial pressure that reduces in case oxidation flavescence process.Yet generally speaking, ventilating fully and removing water vapour to obtain acceptable product.For color and quality product, very short time of drying is normally favourable.

In drying process, the residual monomer content in the polymer beads also reduces, and the initiator of final residual also is destroyed.

Thereafter, will grind and classification through the exsiccant polymer gel, the device that is used to grind generally includes single-stage (singlestage) or multistage roller mill (being preferably secondary or three grades of roller mills), sells bar type grinding machine (pin mill), hammer grinding machine or vibration mill.Usually inner also undried excessive gel piece is elastic; When grinding, can have problems and preferably before grinding, remove, this removal process can realize with simple mode through air blast process (wind sifting) or through screen cloth (" the protection screen cloth " of grinding machine).In view of employed grinding machine, the mesh size of screen cloth should be chosen as and make the breaking of excessive, the elastic granule that produces minimum degree.

Excessive, fully do not grind ground superabsorbent particles (in health product) in it is mainly used and can be used as coarse particle and feel such as diaper; It has also reduced the average initial swelling ratio of super-absorbent.The two is not expected.Therefore, advantageously, the coarse grain polymer beads is removed from product.This realizes through progressive operation usually, for example air blast process or through mesh size for 1000 μ m at the most, preferred 900 μ m at the most, more preferably at the most 850 μ m and most preferably at the most the screen cloth of 800 μ m sieve.For example, use the screen cloth of mesh size 700 μ m, 650 μ m or 600 μ m.Through the crude polymer particle of removing (" oversize (oversize) "),, can return to and grind and screening circulation or further processing individually in order to optimize cost.

The polymer beads that granularity is low excessively can reduce perviousness (SFC).Therefore, also advantageously, thin polymer beads is removed in this classification process.If sieve, this point can be easily through mesh size at the most 300 μ m, preferred 200 μ m at the most, more preferably at the most 150 μ m and most preferably at the most the screen cloth of 100 μ m realize.Thin polymer beads (" undersize (undersize) " or " fine powder ") through removing for cost optimization, can return in the monomer stream, in the polymeric gel or before desiccant gel, return in the complete polymeric gel on demand.

The mean particle size of the polymer beads that shifts out as product section is at least 200 μ m, preferably at least 250 μ m and more preferably at least 300 μ m usually, usually 600 μ m and more preferably 500 μ m at the most at the most.The proportion of particles that granularity is at least 150 μ m is at least 90 weight % usually, more preferably is at least 95 weight % and most preferably be at least 98 weight %.The proportion of particles that granularity is at most 850 μ m is at least 90 weight % usually, more preferably is at least 95 weight % and most preferably be at least 98 weight %.

Among other known super-absorbent preparing methods (especially in suspension polymerization, spray polymerization or dropping liquid polymerization), size-grade distribution is by the method parameters of choice is confirmed at some.These methods directly obtain the particulate state super-absorbent of desired particle size, and common like this saving ground and the screening step.(especially for spraying or dropping liquid polymerization) often also can be saved special drying step in certain methods.

So the polymkeric substance of preparation has ultra absorption characteristic and is included in the term " super-absorbent ".Its CRC is usually than higher, but its AUL or SFC are lower.This type not crosslinked super-absorbent in back, surface is commonly referred to " stock polymer ", so that itself and the crosslinked super-absorbent in back, surface that is made by it are distinguished.

Suitable back linking agent be comprise can with the compound of the group of at least two Cheng Jian of functional group of superabsorbent particles.For common on the market super-absorbent based on acrylic acid/sodium acrylate, back, suitable surface linking agent be comprise can with the compound of the group of at least two carboxylate group Cheng Jian.Preferred back linking agent has the amide acetals or the carbamate of general formula (I)

Wherein

R ¹Be C ₁-C ₁₂Alkyl, C ₂-C ₁₂Hydroxyalkyl, C ₂-C ₁₂Thiazolinyl or C ₆-C ₁₂Aryl,

R ²Be X or OR ⁶,

R ³Be hydrogen, C ₁-C ₁₂Alkyl, C ₂-C ₁₂Hydroxyalkyl, C ₂-C ₁₂Thiazolinyl or C ₆-C ₁₂Aryl, or X,

R ⁴Be C ₁-C ₁₂Alkyl, C ₂-C ₁₂Hydroxyalkyl, C ₂-C ₁₂Thiazolinyl or C ₆-C ₁₂Aryl,

R ⁵Be hydrogen, C ₁-C ₁₂Alkyl, C ₂-C ₁₂Hydroxyalkyl, C ₂-C ₁₂Thiazolinyl, C ₁-C ₁₂Acyl group or C ₆-C ₁₂Aryl,

R ⁶Be C ₁-C ₁₂Alkyl, C ₂-C ₁₂Hydroxyalkyl, C ₂-C ₁₂Thiazolinyl or C ₆-C ₁₂Aryl, and

X is R ²And R ³Group common ketonic oxygen,

R wherein ¹And R ⁴And/or R ⁵And R ⁶Can be the C of bridging ₂-C ₆Alkane two base and wherein above-mentioned R ¹To R ⁶Group also can have overall for one or two free valency also can be connected at least one suitable substruction through these free valency,

Or polyvalent alcohol; The molecular weight of preferred said polyvalent alcohol be every hydroxyl less than 100g/mol, preferably less than 90g/mol, be more preferably less than 80g/mol, most preferably less than 70g/mol; And do not have vicinal-, geminal-, secondary-or tert-hydroxyl, polyvalent alcohol or be the glycol of general formula (IIa)

HO-R ⁷-OH (IIa)

R wherein ⁷Be formula-(CH ₂) _n-unbranched alkylene, wherein n is that an integer and two hydroxyls in 3 to 20, preferred 3 to 12 are end group, or R ⁷Be unbranched, side chain or cyclic alkylidene, or be the polyvalent alcohol of general formula (IIb)

R wherein ⁸, R ⁹, R ¹⁰, R ¹¹Group is hydrogen, hydroxyl, methylol, '-hydroxyethoxy ylmethyl, 1-hydroxyl third-2-base oxygen ylmethyl, 2-hydroxypropyl oxygen ylmethyl, methyl, ethyl, n-propyl, sec.-propyl, normal-butyl, n-pentyl, n-hexyl, 1 independently of one another; 2-dihydroxy ethyl, 2-hydroxyethyl, 3-hydroxypropyl or 4-hydroxybutyl; Always co-exist in the individual hydroxyl in 2,3 or 4 (preferred 2 or 3), and R ⁸, R ⁹, R ¹⁰, R ¹¹In the group at the most one be hydroxyl,

Or be the cyclic carbonate of general formula (III)

R wherein ¹², R ¹³, R ¹⁴, R ¹⁵, R ¹⁶And R ¹⁷Be hydrogen, methyl, ethyl, n-propyl, sec.-propyl, normal-butyl, sec.-butyl or isobutyl-independently of one another, n is 0 or 1.

Or be general formula (IV) De bisoxazoline

R wherein ¹⁸, R ¹⁹, R ²⁰, R ²¹, R ²², R ²³, R ²⁴And R ²⁵Be hydrogen, methyl, ethyl, n-propyl, sec.-propyl, normal-butyl, sec.-butyl or isobutyl-independently of one another, R ²⁶Be singly-bound, straight chain, side chain or cyclic C ₂-C ₁₂Alkylidene group or gather alkoxyl group two bases by what one to ten oxyethane and/or propylene oxide units formed is had like for example polyoxyethylene glycol dicarboxylicacid.

The back linking agent of preferred general formula (I) has 2-oxazolidine ketone (for example 2-oxazolidone and N-(2-hydroxyethyl)-2-oxazolidone, N-methyl-2-oxazolidone), N-acyl group-2-oxazolidine ketone (for example N-ethanoyl-2-oxazolidone), 2-oxo tetrahydrochysene-1; 3-oxazine, bicyclic amide acetals (5-methyl isophthalic acid-azepine-4 for example; 6-dioxa two ring [3.3.0] octanes, 1-azepine-4; 6-dioxa two ring [3.3.0] octane and 5-sec.-propyl-1-azepines-4,6-dioxa two is encircled [3.3.0] octanes), two-2-oxazolidine ketone and many-2-oxazolidine ketone.

The back linking agent of preferred especially general formula (I) has 2-oxazolidone, N-methyl-2-oxazolidone, N-(2-hydroxyethyl)-2-oxazolidone and N-hydroxypropyl-2-oxazolidone.

The back linking agent of preferred general formula (IIa) has 1, ammediol, 1,5-pentanediol, 1,6-pinakon and 1,7-heptanediol.Other instances of the back linking agent of formula (IIa) have 1,3 butylene glycol, 1,8-ethohexadiol, 1,9-nonanediol and decamethylene-glycol.

Said glycol is preferably water miscible; The water-soluble degree of the glycol of general formula (IIa) under 23 ℃ reach at least 30 weight %, preferably reach at least 40 weight %, more preferably reach at least 50 weight %, most preferably reach 60 weight % at least; Said glycol for example 1, ammediol and 1,7-heptanediol.Even be down those back linking agents of liquid more preferably at 25 ℃.

The back linking agent of preferred general formula (IIb) has butane-1; 2; 3-triol, butane-1; 2,4-triol, glycerine, TriMethylolPropane(TMP), trimethylolethane, tetramethylolmethane, 1-to 3 weight (per molecule) ethoxylated glycerol, trimethylolethane or TriMethylolPropane(TMP) and 1-to 3 weight (per molecule) propoxylated glycerol, trimethylolethane or TriMethylolPropane(TMP).Preferred in addition 2-is ethoxylation or ethoxylated neopentylglycol heavily.Preferred especially 2 heavy and 3 heavy ethoxylated glycerols, NSC 6366,2-methyl isophthalic acid, ammediol and TriMethylolPropane(TMP).

Preferred polyhydric alcohols (IIa) and (IIb) viscosity under 23 ℃ for less than 3000mPas, preferably less than 1500mPas, preferentially less than 1000mPas, be more preferably less than 500mPas, most preferably less than 300mPas.

The back linking agent of preferred especially general formula (III) has ethylene carbonate and Texacar PC.

The back linking agent of preferred especially general formula (IV) has 2,2 '-two (2-oxazolines).

Thereby preferred back linking agent makes side reaction and generates volatility and have minimizing with afterreaction of malodorous compound.Therefore, even the super-absorbent for preparing with preferred back linking agent also is tasteless under wetting regime.

Can use and be selected from the independent back linking agent of the selected scope of preceding text or any mixture of different linking agents.

The consumption of said back linking agent is generally at least 0.001 weight %, preferably at least 0.02 weight %, more preferably at least 0.05 weight %; And 2 weight %, preferably 1 weight %, more preferably 0.3 weight % (for example 0.15 weight % or 0.095 weight % at the most at the most) at the most at the most at the most usually are separately based on the quality meter of the stock polymer that is in contact with it (for example said sieve fraction).

The back is crosslinked extremely carries out on exsiccant polymerizable raw material composition granule through the solution spray with the back linking agent usually.After the spray application, the polymer beads that is coated with the back linking agent carries out heated drying, and back crosslinking reaction can or be carried out in the drying process before dry.If use back, surface linking agent with polymerizable groups, the radical formation thing of the crosslinked also routine capable of using in back, surface or utilize the free yl induction polymerization of high-energy radiation (for example UV-light) through this type group to realize then.This can with the use of back linking agent---it can form covalent linkage or ionic linkage in stock polymer particle surface and functional group---concurrently or alternative itself and carry out.

The spray application of back cross-linking agent solution is preferably carried out in having the mixing tank of movable mixing tool, for example screw mixer, pan type mixer or paddle stirrer, or have the mixing tank of other mixing tools.Yet, preferred especially vertical mixing tank.Yet, also can in fluidized-bed, spray the back cross-linking agent solution.Suitable mixing tank has; For example available from Gebr.

Maschinenbau GmbH; Elsener-Strasse 7-9; 33102 Paderborn;

colter formula mixing machine of Germany; Or available from Hosokawa Micron BV; Gildenstraat 26; 7000 AB Doetinchem,

mixing machine of the Netherlands,

mixing machine or

mixing machine.

Spendable nozzle has no restriction.Suitable nozzle and atomizing system for example are set forth in below with reference in the document:

von Fl ü ssigkeiten [Atomization of Liquids]; Expert-Verlag; Volume 660; Reihe Kontakt & Studium; Thomas Richter (2004) and

[Atomization Technology]; Springer-Verlag; VDI-Reihe, G ü nter Wozniak (2002).Can use single the dispersion and polydisperse spraying system.In polydisperse system, single material (single substance) pressurized nozzles (forming jet flow or laminar flow), rotary atomizer, two material spraying gun, ultrasonic atomizer and impinging injector are suitable.For two materials (two-substance) spraying gun, liquid phase can be mixed with gas phase inner or outside.The spraying curve (profile) of nozzle is not crucial, can present any desired shape, for example circular jet flow, planar spray, wide angle round-shaped pattern or annulus spraying curve.It is favourable using non-oxidizing gas when using two material spraying gun, special nitrogen, argon gas or carbonic acid gas.Liquid to be sprayed can be conducted to this type nozzle adding to depress.Liquid to be sprayed can reduce pressure in nib when reaching specific minimum velocity at it and atomize.In addition, also can use single substance nozzle for the purposes of the present invention, for example the slit type die or the bump chamber (solid-cone (type) nozzle) (for example available from D ü sen-Schlick GmbH, Germany or Spraying Systems Deutschland GmbH, Germany).This type nozzle also is set forth in EP 0 534 228 A1 and EP 1 191 051 A2.

Said back linking agent uses with the form of the aqueous solution usually.When only making water, advantageously tensio-active agent or deagglomeration auxiliary agent are added back cross-linking agent solution or actual the adding in the stock polymer as solvent.This can improve wettability and be lowered into piece trend.

All negatively charged ion, positively charged ion, nonionic and amphoterics all are suitable as the deagglomeration auxiliary agent, but consider skin compatibility, preferred nonionic and amphoterics.This tensio-active agent also can comprise nitrogen.For example, add anhydrosorbitol monoesters (for example anhydrosorbitol list cocounut oil acid esters and Span 20) or its ethoxylation variant (for example Polysorbat

).Other suitable deagglomeration auxiliary agents have the ethoxylation and the alkoxy derivative of 2-propyl enanthol; It sells (BASF SE with Lutensol and Lutensol

trade mark; Carl-Bosch-Strasse 38; 67056 Ludwigshafen, Germany).

The deagglomeration auxiliary agent can be metered into individually or add in the cross-linking agent solution of back.Preferably only the deagglomeration auxiliary agent is added in the cross-linking agent solution of back.

The consumption of deagglomeration auxiliary agent based on the stock polymer meter, is 0 to 0.1 weight % for example, preferred 0 to 0.01 weight %, more preferably 0 to 0.002 weight %.The deagglomeration auxiliary agent preferably is metered into; So that the surface tension of the aqueous extract of crosslinked water absorbent polymer is 0.060N/m at least, preferably 0.062N/m, more preferably 0.065N/m at least at least behind 23 ℃ of following swollen stock polymers and/or swollen, and 0.072N/m at the most advantageously.

The aqueous solution of back linking agent except containing at least a back linking agent, also can comprise cosolvent.The content of non-aqueous solvent or the total amount of solvent can be used for regulating the degree of depth that the back linking agent penetrates into polymer beads.The cosolvent that is easy to get in the industry has the C1-C6 alcohols, for example methyl alcohol, ethanol, n-propyl alcohol, Virahol, propyl carbinol, sec-butyl alcohol, the trimethyl carbinol or 2-methyl isophthalic acid-propyl alcohol; The C2-C5 glycols, terepthaloyl moietie, 1 for example, 2-Ucar 35 or 1,4-butyleneglycol; Ketone, for example acetone; Or carboxylic acid esters, for example ETHYLE ACETATE.The shortcoming of some said cosolvent is that it has typical intrinsic smell.

Ideally, cosolvent originally is not the back linking agent under reaction conditions.Yet under border condition and according to the residence time and temperature, cosolvent also can be to crosslinked some contribution.Thereby especially in the back linking agent be relative inertness and be above-mentioned situation when also can be used as himself cosolvent, for example in the situation of the polyvalent alcohol of the glycol of the cyclic carbonate that uses general formula (III), general formula (IIa) or general formula (IIb).Linking agent can be used as with the mixture use of bigger active back linking agent or as cosolvent and uses behind this type; Because real back crosslinking reaction is compared with the situation that does not contain bigger active linking agent, can under lower temperature and/or with the shorter residence time, carry out subsequently.Because cosolvent uses with bigger amount and part is retained in the product, so it must be nontoxic.

Also be suitable as the inventive method cosolvent be the glycol of general formula (IIa), the polyvalent alcohol of general formula (IIb) and the cyclic carbonate of general formula (III).It can be in general formula (I) and/or active back linking agent and/or two (IV)-or this function of realization down of triglycidyl group compound.Yet the cosolvent of preferred the inventive method is the glycol of general formula (IIa) especially, especially when the reaction of hydroxyl is obstructed because of the adjacent group space.Though this type glycol also is suitable as the back linking agent in principle, this need be than obvious higher temperature of reaction or the randomly higher consumption of no sterically hindered glycol.

The binding substances of linking agent cosolvent and active back linking agent has polyvalent alcohol and the amide acetals of general formula (I) or the binding substances of carbamate of two pure and mild general formulas (IIb) of preferred polyhydric alcohols, general formula (IIa) behind the preferred especially low activity.

Suitable binding substances has, 2-oxazolidone/1 for example, 2-Ucar 35 and N-(2-hydroxyethyl)-2-oxazolidone/1,2-Ucar 35, and ethylene glycol diglycidylether/1,2-Ucar 35.

Preferred very especially binding substances has 2-oxazolidone/1, ammediol and N-(2-hydroxyethyl)-2-oxazolidone/1, ammediol.

Other preferred binding substancess have ethylene glycol diglycidylether or glyceryl two-or the binding substances of triglycidyl ether and following solvent, cosolvent or co-crosslinker: Virahol, 1, ammediol, 1,2-Ucar 35 or its mixture.

Other preferred binding substancess have 2-oxazolidone or (2-hydroxyethyl)-2-oxazolidone those binding substancess in following solvent, cosolvent or co-crosslinker: Virahol, 1; Ammediol, 1,2-Ucar 35, ethylene carbonate, Texacar PC or its mixture.

Usually, the concentration in the cross-linking agent aqueous solution is 15 to 50 weight %, preferred 15 to 40 weight %, more preferably 20 to 35 weight % to cosolvent in the back, based on back cross-linking agent solution meter.For the situation of the cosolvent that only has limited water miscibility, make and only have a phase thereby advantageously regulate the back cross-linking agent aqueous solution, randomly implement through the concentration that reduces cosolvent.

In a preferred embodiment, do not use cosolvent.Back linking agent just uses with the form of solution in the water, randomly adds the deagglomeration auxiliary agent.

The concentration of at least a back linking agent in the aqueous solution of back linking agent is generally 1 to 20 weight %, preferred 1.5 to 10 weight %, more preferably 2 to 5 weight %, based on back cross-linking agent solution meter.

Based on stock polymer, the total amount of back cross-linking agent solution is generally 0.3 to 15 weight %, preferred 2 to 6 weight %.

The real back, surface of carrying out through the functional group reactions that makes surface back linking agent and stock polymer particle surface place is crosslinked carries out through heating wetting stock polymer of cross-linking agent solution after surperficial usually; Be commonly referred to " drying " (but the above-mentioned drying of the polymer gel that does not obtain with polymerization obscure, wherein must remove much more liquid usually).Said drying can be in mixing tank itself through to the chuck heating, through heat exchange surface or blast hot gas and carry out.Can carry out the blending and the drying of super-absorbent and back, surface linking agent simultaneously, for example in fluidized bed dryer, realize.Yet said drying is carried out in downstream dryer usually, but for example pan dryer, revolving tubular furnace, oar formula or disk dryer or heating spiral rod.Suitable moisture eliminator has; For example available from Bepex International LLC; 333 N.E.Taft Street; Minneapolis, MN 55413, of U.S.A. or

moisture eliminator; Or available from Nara Machinery Co.; Ltd., European Branch, Europaallee 46; 50226 Frechen, the pedal-type dryer of Germany or fluidized bed dryer.

Can be in downstream dryer through contact surface heated polymerizable composition granule to carry out drying and to implement the back, surface crosslinked, rare gas element that maybe can be through supplying heat or through a kind of or more kinds of rare gas element and steam mixture or only use steam to heat.For situation, can in rare gas element, react at a little or under reducing pressure completely through contact surface supply heat.For the situation of using steam direct heating polymer beads, the operation moisture eliminator under the pressure of standardpressure or raising advantageously according to the present invention.In this case, advantageously will the back cross-linking step be divided into the heating steps that uses steam and at rare gas element but do not contain the reactions step under the steam.This can realize in one or more device.According to the present invention, polymer beads can just be used steam heating in the crosslinked mixing tank in back.Employed stock polymer still can have 10 to 120 ℃ temperature in the operation steps formerly; Back cross-linking agent solution can have 0 to 70 ℃ temperature.Especially, can heat the back cross-linking agent solution to reduce viscosity.

Preferred drying temperature 100 to 250 ℃, preferred 120 to 220 ℃, more preferably 130 to 210 ℃, most preferably in 150 to 200 ℃ the scope.Be preferably at least 10 minutes in the preferred residence time in reaction mixer or moisture eliminator under this temperature, more preferably at least 20 minutes, most preferably at least 30 minutes, and at the most 60 minutes usually.Usually; Carry out drying so that the residual regain of super-absorbent is generally at least 0.1 weight %, preferably at least 0.2 weight % and at least 0.5 weight % most preferably, and 15 weight %, preferably 10 weight % and more preferably 8 weight % at the most at the most at the most usually.

Crosslinked can under standard atmosphere conditions, the carrying out in back." standard atmosphere conditions " refers to and do not take the dividing potential drop of technical measures with the oxidizing gas (for example atmosphericoxygen) in the device (" back crosslinking reaction device " is generally moisture eliminator) that reduces wherein main generation back crosslinking reaction.Yet, preferably depress and carry out the back crosslinking reaction at the oxidizing gas branch that reduces.Oxidizing gas be the vp under 23 ℃ be at least 1013mbar and in combustion processes as the material of oxygenant, for example oxygen, nitrogen oxide and nitrogen peroxide, especially oxygen.The dividing potential drop of oxidizing gas preferably less than 140mbar, preferably less than 100mbar, be more preferably less than 50mbar, most preferably less than 10mbar.When crosslinked under environmental stress after the heat, when promptly carrying out under the about 1013mbar of stagnation pressure, the total dividing potential drop of oxidizing gas is confirmed by its volume ratio.The ratio of oxidizing gas preferably less than 14 volume %, preferably less than 10 volume %, be more preferably less than 5 volume %, most preferably less than 1 volume %.

The back is crosslinked can be under reduced pressure, and promptly stagnation pressure is less than carrying out under the 1013mbar.Stagnation pressure usually less than 670mbar, preferably less than 480mbar, be more preferably less than 300mbar, most preferably less than 200mbar.When dry and back are crosslinked when in oxygen content is the air of 20.8 volume %, carrying out; Oxygen partial pressure corresponding to above-mentioned stagnation pressure is 139mbar (670mbar), 100mbar (480mbar), 62mbar (300mbar) and 42mbar (200mbar), is concrete stagnation pressure in the bracket.The another kind of method that reduces the oxidizing gas dividing potential drop is to introduce non-oxidizing gas to being used for the crosslinked device in back, especially rare gas element.Suitable rare gas element is the material that does not have oxygenizement in the component that in the crosslinked moisture eliminator in back, exists with gas form under back crosslinking temperature and the specified pressure and under these conditions, dried polymer pellets is used; For example nitrogen, carbonic acid gas, argon gas, steam, nitrogen.The amount of rare gas element is generally 0.0001 to 10m ³, preferred 0.001 to 5m ³, more preferably 0.005 to 1m ³And most preferably 0.005 to 0.1m ³, based on 1kg super-absorbent meter.

In the method for the invention,---it does not comprise steam---can blast in the crosslinked moisture eliminator in back through nozzle if rare gas element; Yet, especially preferably through the blending super-absorbent with surface back linking agent via be physically located in the mixing tank or only the nozzle at the mixing tank upper reaches in the polymer beads logistics, add rare gas element.

Should understand the steam of the cosolvent that from moisture eliminator, removes can be in the moisture eliminator outside condensation and randomly circulating once more.

In a preferred embodiment of the invention, except back linking agent, also in the crosslinked forward and backward cross-linking process in back or after afterwards crosslinked, polyvalent cation is applied to particle surface.This is that the back, other surface of carrying out through the ion non covalent bond is crosslinked on the principle, but is also referred to as with said metals ion " complexing " sometimes or simply is called with said material (" complexing agent ") " coating ".

Said polyvalent cation use through divalence-or polyvalent cation (normally divalence-, trivalent-or the tetravalent metal positively charged ion) and the spray application of the solution of polyvalent cation (polymkeric substance that for example completely or partially forms in form) by the vinyl-amine monomer realize; Said polymkeric substance is the polyvinyl lactam of hydrolysis (so-called " polyvinylamine ") partially or completely for example,---under very high pH value---partly exists to obtain ammonium with protonated form even its amido always.The instance of available divalent metal is the divalent cation of 2 families of the periodic table of elements (especially Mg, Ca, Sr, Ba), 7 families (especially Mn), 8 families (especially Fe), 9 families (especially Co), 10 families (especially Ni), 11 families (especially Cu) and 12 families (especially Zn) metal especially.The instance of available trivalent metal cation is the Tricationic of 3 families that comprise group of the lanthanides of the periodic table of elements (especially Sc, Y, La, Ce), 8 (especially Fe), 11 families (especially Au) and 13 families (especially Al) metal especially.The instance of available quadrivalent cation is the quadrivalent cation of the group of the lanthanides of the periodic table of elements (especially Ce) and 4 families (especially Ti, Zr, Hf) metal especially.Said metallic cation can use separately or use with the form of each other mixture.Especially preferably use trivalent metal cation.Very especially preferably use aluminium cations.

In the metallic cation of mentioning, suitable metal-salt is that all have enough solubleness those in solvent to be used.Specially suitable metal-salt is to contain those of weak complex anion, for example muriate, nitrate salt and vitriol, hydrosulfate, carbonate, supercarbonate, nitrate salt, phosphoric acid salt, hydrophosphate or dihydrogen phosphate.Preferred list-and dicarboxylicacid, hydroxy acid, ketone acid and amino acid whose salt or basic salt.Instance has acetate, propionic salt, tartrate, PHENRAMINE MALEATE, Citrate trianion, lactic acid salt, malate and SUMATRIPTAN SUCCINATE.Equally preferably use oxyhydroxide.Especially preferably use 2-hydroxyl carbonate (for example Citrate trianion and lactic acid salt).The instance of preferred especially metal-salt has basic metal and alkali earth metal aluminate and hydrate thereof, for example sodium aluminate and hydrate thereof, aluminum acetate, propionic acid aluminium, Tiorco 677 and Aluctyl.

Mentioned positively charged ion and salt can be pure form use or use with the form of mixtures of different positively charged ions or salt.Employed divalence-and/or the salt of trivalent metal cation can comprise other second components, an alkali metal salt of for example still unneutralized carboxylic acid and/or neutral carboxylic acid.Preferred an alkali metal salt is sodium salt and sylvite, and ammonium salt.It uses with the form of the aqueous solution usually, and the said aqueous solution is through obtaining solid salt is soluble in water; Or preferably directly obtain with itself, avoided any drying and purification step like this.Advantageously, also can use the hydrate of mentioned salt, it is more soluble in water quickly than anhydrous salt usually.

The usage quantity of metal-salt is generally at least 0.001 weight %, preferably at least 0.01 weight % and more preferably at least 0.1 weight %; At least 0.4 weight % for example; And 5 weight %, preferably 2.5 weight % and more preferably 1 weight % at the most at the most at the most usually; 0.7 weight % at the most for example is separately based on the quality meter of stock polymer.

The salt of trivalent metal cation can solution or the form of suspension-s use.The solvent that is used for metal-salt can be the mixture of water, alcohols, DMF, DMSO and these components.Special preferably water and water/alcohols mixture, for example water/methyl alcohol, water/1,2-Ucar 35 and water/1, ammediol.

Stock polymer comprises drying step to handle with the solution of divalence or polyvalent cation with using the identical mode of back, surface linking agent processing.Surface back linking agent and the combinable solution of polyvalent cation or independent solution form are sprayed.Can before or after crosslinked behind the surface, carry out to superabsorbent particles spray application metal salt solution.In a special preferable methods; The spray application of metal salt solution and the spray application of cross-linking agent solution are carried out in same step; Two kinds of solution separately and in turn or side by side spray through two nozzles, or linking agent and metal salt solution can be sprayed through a nozzle together.

If crosslinked behind the surface and/or handle with complexing agent after carry out drying step, behind drying step, be favourable but be not absolute necessary the product cooling.Said cooling can be carried out continuously or off and on; For this reason, product is sent in the water cooler that is connected in the moisture eliminator downstream easily continuously.For this reason; Can use the device that is used for removing heat of any known from powdery solid; Especially mention any device more than as drying installation; Condition for be not dress with heating medium but dress with heat-eliminating medium (for example water coolant), thereby do not have heat not have heat to pass through agitating unit or other heat exchange surfaces are introduced in the super-absorbent through wall and according to structure yet, but from wherein removing.The water cooler that preferably uses product to move therein, promptly through the refrigerative mixing tank, for example oar formula water cooler or disc type water cooler.Super-absorbent also can cool off through blasting cooling gas (for example cooling air) in fluidized-bed.Confirm that cooling conditions is to obtain having the super-absorbent of the required temperature of further processing.Usually; Mean residence time in water cooler confirms as at least 1 minute usually, preferably at least 3 minutes and more preferably at least 5 minutes; And at the most 6 hours, preferably at the most 2 hours and more preferably at the most 1 hour usually; Cooling operation is generally at least 0 ℃, preferably at least 10 ℃ and more preferably at least 20 ℃ for the temperature that make to generate product, and at the most 100 ℃, preferably at the most 80 ℃ and more preferably at the most 60 ℃ usually.

Crosslinked super-absorbent is randomly pulverized in a usual manner and/or is sieved behind the surface.Pulverizing is normally unwanted at this, but screens out formed agglomerate or fine powder is suitable for setting up required product size-grade distribution usually.Agglomerate and fine powder or abandon or preferably circulate in known manner and get in the said method at suitable point; Agglomerate circulates after pulverizing and gets in the said method.The required granularity of crosslinked super-absorbent and stock polymer is identical behind the surface.

Randomly provide the additive that other have the stabilization that suppresses variable color in the super-absorbent of the present invention.

The stablizer that known this type suppresses variable color has, for example sulfinate derivant.Specially suitable sulfinate derivant has, and for example descends the mixture of compound, its salt or said compound and/or its salt of formula V:

Wherein

M is valent metal ion or the divalent-metal ion of monovalent (one equivalent) of 1 family, 2 families, 8 families, 9 families, 10 families, 12 families or 14 families of Wasserstoffatoms, ammonium ion, the periodic table of elements;

R ²⁷Be OH or NR ³⁰R ³¹, R wherein ³⁰And R ³¹Be H or C independently of one another ₁-C ₆Alkyl;

R ²⁸Be H or alkyl, thiazolinyl, naphthenic base or aryl, wherein this group randomly has 1,2 or 3 substituting group, and it is selected from C independently of one another ₁-C ₆Alkyl, OH, O-C ₁-C ₆Alkyl, halogen and CF ₃And

R ²⁹Be COOM, SO ₃M, COR ³⁰, CONR ³⁰R ³¹Or COOR ³⁰, wherein M, R ³⁰And R ³¹Each is above freely define or---work as R ²⁸For randomly as more than during specified substituted aryl---be H,

In last formula V, alkyl represent has preferred 1-6 and especially the straight or branched alkyl of 1-4 carbon atom.The instance of alkyl has methyl, ethyl, n-propyl, sec.-propyl, normal-butyl, the tertiary butyl, n-hexyl etc.This also is applicable to the alkyl in the O-alkyl.The thiazolinyl representative has the straight or branched thiazolinyl of preferred 3-8 a carbon atom, an especially 3-6 carbon atom.Preferred thiazolinyl is an allyl group.Naphthenic base is C especially ₁-C ₆Naphthenic base, preferred especially cyclopentyl and cyclohexyl.Aryl (comprising the aryl in the aralkyl) is preferably phenyl or naphthyl.When aryl is a phenyl and when being substituted, it preferably has two substituting groups.They especially are on 2 and/or 4.

Halogen is F, Cl, Br and I, preferred Cl and Br.

M is preferably the earth alkali metal or the zine ion of ammonium ion, alkalimetal ion or monovalent.Suitable alkalimetal ion is sodium and potassium ion especially; Suitable alkaline earth metal ion is magnesium, strontium and calcium ion particularly.

R ²⁷Be preferably hydroxyl or amino.

R ²⁸Be preferably Wasserstoffatoms or can be like the substituted alkyl or aryl of preceding text.It preferably has one or two hydroxyl and/or alkoxy substituent.

R ²⁹Be preferably COOM or COO R ³⁰(M and R ³⁰Specified and define like preceding text separately) or---R worked as ²⁷For can be the time like the specified substituted aryl of preceding text---also be Wasserstoffatoms.

In a preferred embodiment, super-absorbent comprises such following formula compound, and wherein M is the earth alkali metal or the zine ion of alkalimetal ion or monovalent; R ²⁷Be hydroxyl or amino; R ²⁸Be H or alkyl and R ²⁹Be COOM or COO R ³⁰, wherein work as R ²⁹During for COOM, the M in this COOM group is the alkaline earth metal ion of H, alkalimetal ion or monovalent, works as R ²⁹Be COO R ³⁰The time, R ³⁰Be C ₁-C ₆Alkyl.

In another preferred embodiment, super-absorbent comprises such following formula compound, and wherein M is the earth alkali metal or the zine ion of alkalimetal ion or monovalent; R ²⁷Be hydroxyl or amino; R ²⁸For randomly specifying substituted aryl like preceding text, especially hydroxy phenyl or C ₁-C ₄Alkoxyl phenyl; R ²⁹Be Wasserstoffatoms.

Existing IUPAC (International Union of Pure and Applied Chemistry(IUPAC) (International Union of Pure and Applied Chemistry); 104T.W.Alexander Drive; Building 19; Research Triangle Park, NC 27709, U.S.A.; Www.iupac.org) 1 family (H, Li, Na, K, Rb, Cs, Fr) of the periodic table of elements of---international organization that names in the chemical charge field---numbering, 2 families (Be, Mg, Ca, Sr, Ba, Ra), 8 families (Fe, Ru, Os), 9 families (Co, Rh, Ir), 10 families (Ni, Pd, Pt), 12 families (Zn, Cd, Hg) and 14 families (C, Si, Ge, Sn, Pb) are corresponding to CAS (CAS; 2540Olentangy River Road, Columbus, OH 43202; U.S.A., www.cas.org) Ia family, IIa family, IIb family, IVa family and the VIIIb family in the employed numbering.

The sulfinate derivant of following formula can be pure form use, but also can be randomly to use with the form of the mixture of the sulphite of corresponding metal ion and corresponding sulfonic acid---it generates in the said compound of preparation in a usual manner---.The preparation of the sulfinate derivant of said following formula is known and is set forth in for example WO 99,/18 067 A1.Commercially available prod that their are still conventional and for example sodium salt, the 2-hydroxyl-disodium salt of 2-sulfonic group acetate and the mixture of sodium sulfite anhy 96 of 2-hydroxyl-2-sulfino acetate form with

FF6M or

FF7 perhaps the trade(brand)name of FF6M or

FF7 (Salzstrasse 131 available from L.Br ü ggemann KG; 74076 Heilbronn; Germany, www.brueggemann.com).

Super-absorbent of the present invention is also randomly admixed with at least a water-fast inorganic particulate solid.In principle, any water-fast inorganic powder is suitable for this purpose.Instance has the normally material of solid, unreactiveness (promptly in super-absorbent, being nondestructive), for example oxide compound, oxide hydroxide (oxide hydroxide), oxyhydroxide, vitriol, carbonate, zeolite, mineral dye, mineral substance or clay.Instance has vitriol, for example sal epsom or permanent white; Carbonate, for example lime carbonate, magnesiumcarbonate or rhombspar; Silicate, for example Calucium Silicate powder or Magnesium Silicate q-agent; Carbide, for example perlite or silit, zeyssatite or floating dust.

The MOX that suitable oxide compound has 2 families of family to 14 of the periodic table of elements---to comprise group of the lanthanides and actinium series---.The instance of specially suitable oxide compound has Natural manganese dioxide, quicklime, strontium oxide, barium oxide, titanium oxide, ZIRCONIUM DIOXIDE 99.5, vanadium oxide, chromic oxide, molybdenum oxide, Tungsten oxide 99.999, Manganse Dioxide, red stone, powder blue, nickel oxide, cupric oxide, zinc oxide, boron oxide, aluminum oxide, silicon-dioxide, White tin oxide, plumbous oxide, lanthanum trioxide or cerium oxide.For clarity sake: the popular name of using MOX is not the stoichiometry that is intended to explain the valence state and the oxide compound of metal.If a kind of element forms more than a kind of oxide compound, then these oxide compounds all are suitable usually.Under individual cases, according to the concrete consideration of individual cases and the selective oxidation thing, for example according to cost, toxicity, stability or color.The silicon-dioxide that the instance of specially suitable oxide compound has titanium oxide (especially in anatase octahedrite or rutile polymorphic form), precipitated silica or prepares through pyrolysis.

Clay is silicate or aluminosilicate, and it obtains through exploiting natural sediment and also it further being processed sometimes usually.Yet some clays are synthetic preparations.

Also can use the mixture of these materials.

Said water-fast inoganic solids is granular; It is a powder-form.Mean particle size is usually at least 0.001 μ m, preferred at least 0.002 μ m, more preferably at least 0.005 μ m and most preferably at least 0.01 μ m and 500 μ m, preferred 200 μ m at the most, more preferably 100 μ m and most preferably at the most in the scope of 50 μ m at the most at the most usually.Said particle itself can be the aggregate or the agglomerate of littler primary particle.Said particle diameter can be measured through screen analysis, but a kind of simpler and thereby preferable methods be to measure particle diameter through laser diffractometry.These methods be known and on the suitable and commercially available instrument that gets routine operation.

Aforementioned optional other suppress the stablizer and the water-fast inorganic particulate solid of variable colors; When they add fashionable; Its add-on is generally at least 0.0001 weight %, preferably at least 0.001 weight % and more preferably at least 0.025 weight % separately; Usually 3 weight %, preferably 2 weight % and more preferably 0.5 weight % at the most at the most at the most are separately based on the gross weight meter of super-absorbent of the present invention.Generally speaking, comprise the situation of alkaline earth salt, compare during with the alkali-free earth metal salt, need the stablizer of the known inhibition variable color of less amount for super-absorbent of the present invention.

Super-absorbent can be through any known blending means mix with the stablizer of inhibition variable color used according to the invention, optional other stablizers and water-fast inorganic particulate solid.Stablizer of inhibition variable color used according to the invention---when being solid form---and water-fast inorganic particulate solid are sneaked into material itself or as the suspensoid in solvent or the suspension medium; The stablizer of inhibition variable color used according to the invention---when for dissolving or liquid form---can randomly also be sneaked into solution or liquid form with other optional stablizers.Owing to be easier to uniform distribution, said stablizer is preferably sneaked in the super-absorbent with the form of powder or suspension-s.This not necessarily obtains can be through mechanical means with the isolating physical mixture of plain mode.Said additive very might form combining of more confirming with super-absorbent, for example with the form of more firm adherent surface layer or with the particle form on the surface that is attached to superabsorbent particles securely.Additive is sneaked into known super-absorbent also can be understood that and be called " coating ".

If solution or suspension-s are used for coating, then employed solvent or suspension medium be and super-absorbent and additive the two equal chemical compatible solvent or suspension medium, the chemical reaction that promptly can not expect arbitrarily with its generation.Usually, make water or organic solvent, for example alcohol or polyvalent alcohol, or its mixture.The suitable solvent or the instance of suspension medium have water, isopropanol, 1, ammediol/water and propylene glycol/water, and wherein mass mixing ratio is preferably 20: 80 to 40: 60.When suspension medium was used for stablizer used according to the invention or particulate inorganic solid, water was preferred.Tensio-active agent can add in said solution or the suspension-s.

If stablizer and other additives---they are not added in monomer mixture or the polymeric gel---are as mentioned below usually to mix with super-absorbent to be used for crosslinked solution or the identical mode of suspension-s in back, surface with comprising surface back linking agent and be applied to super-absorbent.Said additive can be used as the composition that is used for one of the crosslinked solution in back, surface or its component and is applied to (still) not crosslinked super-absorbent (" stock polymer ") in back, in one of the solution of back, the surface of additive adding soon linking agent or its component.With after the super-absorbent of surface back linking agent and additive coating through crosslinked other the required operation stepss in back, surface, the reaction of linking agent and super-absorbent behind the for example thermoinducible surface.Fairly simple and the economically feasible of this method.

The stability of the inhibition variable color of superelevation if desired, then stablizer and additive are preferably used in the specialized operations step in crosslinked back behind the surface.If stablizer and additive be with the administered of solution or suspension-s, then to the crosslinked super-absorbent in back, surface use with the mode that linking agent is identical after the stock polymer application surface is carried out.Common but optional, carry out thereafter---in cross-linking step behind the surface---heating, with the after drying super-absorbent.Yet at the most 110 ℃, preferably at the most 100 ℃ and more preferably at the most 90 ℃ usually of the temperature of in this drying step, confirming are to prevent the not reaction of desired additive.Attemperation is so that---in view of the residence time in drying unit---obtain the water ratio of required super-absorbent.Also maybe and be easily fully; Additive adds separately or together adds with other conventional auxiliary agents; For example in the water cooler that is connected to cross-linking step downstream, back, surface, add; Said conventional auxiliary agent is the water of dust-proofing agent, anti-hard caking agent or rewetting super-absorbent for example, like the description of hereinafter to these auxiliary agents.In this case the temperature of polymer beads be 0 ℃ to 190 ℃, preferably less than 160 ℃, be more preferably less than 130 ℃ even be more preferably less than 100 ℃ and most preferably less than 70 ℃.Said polymer beads randomly is cooled to the temperature that is lower than any additives decompose temperature rapidly after coating.

Can be randomly in any operation steps of said preparation method, use---all known coating if desired---in addition to superabsorbent particles surface (no matter the back is crosslinked or the back is crosslinked); For example film-forming polymer, thermoplastic polymer, dendrimer (dendrimer), polycationic polymer (for example polyvinylamine, polymine or PAH); Or all water-soluble monos well known by persons skilled in the art-or polyvalent metal salt, for example Tai-Ace S 150, sodium salt, sylvite, zirconates or molysite.The instance of available an alkali metal salt has sodium sulfate and vitriolate of tartar, and Sodium.alpha.-hydroxypropionate and Potassium.alpha.-hydroxypropionate, Trisodium Citrate and Tripotassium Citrate and sodium sorbate and POTASSIUM SORBATE GRANULAR WHITE.This can obtain other effect, for example the caking trend of the reduction of final product or midbody, improved processing characteristics or the further salt solution water conservancy diversion rate (SFC) that increases in said preparing method's specific operation step.When additive was used to spray with the form of dispersion-s, it was preferably used as aqueous dispersion, and preferably uses dust-proofing agent in addition so that said additive is fixed in the surface of super-absorbent.Said dust-proofing agent directly adds in the dispersion-s of powdery inorganic additives; Randomly, it also can be used as independent solution before using the powdery inorganic additives, in the process or add through spray application afterwards.Most preferably simultaneously linking agent, dust-proofing agent and powdery inorganic additives after the spray application in the cross-linking step of back.Yet in another preferable methods modification, dust-proofing agent adds in water cooler separately, for example through up, below or carry out spray application from the side.Also can be used for making specially suitable dust-proofing agent that the powdery inorganic additives is fixed in the water-absorbing polymer particles surface that heavily ethoxylation polyvalent alcohol (for example TriMethylolPropane(TMP), glycerine, sorbyl alcohol and NSC 6366) of polyoxyethylene glycol (molecular weight be 400 to 20000g/mol), poly-glycerol, 3-to 100 is arranged.Specially suitable have 7-to 20 to weigh ethoxylated glycerol or TriMethylolPropane(TMP); For example Polyol TP

(Perstorp, Sweden).More specifically, the latter has the capillary advantage of the aqueous extract that only slightly reduces water-absorbing polymer particles.

Can regulate super-absorbent of the present invention to required water cut through adding water equally.

All coating, solid, additive and auxiliary agent can independently add in the operation steps separately;---they do not add in the process that stock polymer and back, surface linking agent are admixed---adds in water cooler in the super-absorbent if but the method for common most convenient is with them, for example adds through the spray application of solution or with solid form in small, broken bits or liquid form.

The centrifugal retention volume of super-absorbent of the present invention (CRC, testing method vide infra) is generally at least 5g/g, preferably 10g/g and more preferably 20g/g at least at least.It is no more than 40g/g usually.

Super-absorbent of the present invention---when its when surface back is crosslinked---absorbed dose (AUL0.7psi, testing method vide infra) under pressure is generally at least 18g/g, preferably 20g/g, preferential 22g/g and be no more than 30g/g usually at least at least.

In addition, the salt solution water conservancy diversion rate (SFC, testing method vide infra) of super-absorbent of the present invention is generally at least 10 x 10 ^-7Cm ³S/g, preferred at least 30 x 10 ^-7Cm ³S/g, preferential at least 40 x 10 ^-7Cm ³S/g and be no more than 1000 x 10 usually ^-7Cm ³S/g.

The L value of super-absorbent (CIE chromatic number) under stored condition not, is generally at least 75, preferably at least 80, more preferably at least 85 and at the most 100.

The a value of super-absorbent (CIE chromatic number), under stored condition not, be generally-2.5 to+2.5, preferred-2.0 to+2.0, more preferably-1.5 to+1.5.

The b value of super-absorbent (CIE chromatic number) under stored condition not, is generally 0 to 12, preferred 2 to 11.

After the described hereinafter heavily stressed relatively weathering test; Super-absorbent of the present invention---analyzing the back to L and a value---and comparing with stored condition not, more specifically with preferably be not more than 13, compare more preferably no more than 12 b value, only have the result of slight degradation.B value more than 12 is important as far as the women with hygienic articles and ultra-thin diaper; Even the b value greater than 15 also is important in conventional diaper, because this variable color can be awared by the human consumer in use.

The present invention also provides the hygienic articles that comprises super-absorbent of the present invention (preferred ultra-thin diaper); It comprises absorption layer; This absorption layer by 50 to 100 weight %, preferred 60 to 100 weight %, preferential 70 to 100 weight %, more preferably 80 to 100 weight %, most preferably the super-absorbent of the present invention of 90 to 100 weight % is formed, and does not comprise the shell of said absorption layer certainly.

Super-absorbent of the present invention also is very particularly advantageous for the preparation of laminated product and composite structure, described in for example US 2003/0181115 and US 2004/0019342.Except preparing the hot-melt adhesive of the new absorbing structure of this type in being used to described in above-mentioned two pieces of documents and especially by being set forth in US 2003/0181115 and being bonded with the fiber that the hot-melt adhesive of superabsorbent particles forms; Super-absorbent of the present invention also be suitable for through use can be UV-crosslinked Hotmelt Adhesive (it for example prepares the structure of all fours with AC (BASF SE Germany) sells).The advantage that these can UV-crosslinked Hotmelt Adhesive have even can under 120 to 140 ℃, handle; Therefore they can be compatible better with multiple thermoplastic matrix.Another tangible advantage be can be UV-crosslinked Hotmelt Adhesive aspect the toxicity be completely safe and in hygienic articles, can not cause any vaporization yet.Relevant with super-absorbent of the present invention one very significantly advantage be can be UV-crosslinked Hotmelt Adhesive in processing and crosslinked process, be not easy to flavescence.This is especially favourable when preparing the hygienic articles of ultra-thin or partially transparent.Therefore super-absorbent of the present invention and Hotmelt Adhesive that can be UV-crosslinked to combine be particularly advantageous.Suitable Hotmelt Adhesive that can be UV-crosslinked for example is set forth in EP 0 377 199 A2, EP 0 445 641 A1, US 5,026,806, EP 0 655 465 A1 and EP 0 377 191 A2.

Super-absorbent of the present invention also can be used for absorbing in other industrial circles of liquid (the especially water or the aqueous solution).These fields have, for example store, pack, transport (as the component of the wrapping material that are used for water sensitivity or wet quick property goods, for example be used for the flowers transportation, and as the protection thing of resisting mechanical effect); Animal health (in cat litter); Food product pack (the transportation of fish, fresh meat; The absorption of water, blood in fresh fishes or the meat Package); Medicine (trauma agent/ointment, be used for the water-absorbing material of burn dressing or other liquid permeability wounds), makeup (solid support material, rheumatism plaster, ultrasound gel, cooling gel, Thickener in cosmetics, the sunscreen that are used for pharmaceutical chemistry article and medicament); The thickening material that is used for oil/water or water/fat liquor; Textiles (moisture control of textiles, shoe-pad are used for the for example transpiration cooling of vest, gloves, hair filler); Chemical engineering is used (as the catalyzer of organic reaction, be used for fixing big functional molecular such as enzyme, as the tackiness agent in the agglomerate, heat accumulation agent, filtration adjuvant, the hydrophilic component of polymer laminate, dispersion agent, liquifier); Building with build in the industry as powder injection-molded auxiliary agent (install, in the bottom ash based on loam, in auxiliary agent, the cable sheath of tunnel excavation) as antivibration medium, water ground; Water treatment, refuse are removed, water removes (deicing agent, can utilize sandbag again); Cleaning; Agrochemicals industry (maintenance of irrigation, meltwater and dewfall, compost additive, conserve forests avoid the delay in plant of fungi/insect pest invasion and attack, activeconstituents discharge); Be used for fire-fighting or be used for fire prevention; The coextrusion agent of thermoplastic polymer (for example being used for the hydrophilization of multilayer film); Film that preparation can absorb water and thermoplastic molded article (for example are used for storing in agricultural the film of rainwater and dew; Comprise the fruits and vegetables fresh film of super-absorbent to be used to keep pack with wet film; Super-absorbent-PS coextrusion thing for example is used for sheathing foodstuff (for example meat, fish, bird, fruits and vegetables)); Or as the carrier substance (medicine, Crop protection) of active agent preparation.

The goods that the present invention is used for absorption fluids are that with the different of known embodiment it comprises super-absorbent of the present invention.

Also found a kind of method of absorption fluids with goods (especially hygienic articles) that be used to prepare, it is included in the said goods of preparation and uses at least a super-absorbent of the present invention.In addition, be known through the method for using super-absorbent to prepare said goods.

Testing method

Super-absorbent is tested with the testing method of following description.

The standard method of test of below describing that is called " WSP " is set forth in: " Standard Test Methods for the Nonwovens Industry ", and 2005 editions, by Worldwide Strategic Partners EDANA (European Disposables and Nonwovens Association; Avenue Eugene Plasky, 157,1030 Brussels; Belgium, www.edana.org) and INDA (Association of the Nonwoven Fabrics Industry, 1100 Crescent Green; Suite 115, Cary, North Carolina 27518; U.S.A., www.inda.org) combined publication.This publication can be available from EDANA and INDA.

All tests of below describing should---be carried out under the relative air humidity of 23 ± 2 ℃ envrionment temperature and 50 ± 10% unless otherwise mentioned---.Unless otherwise mentioned, superabsorbent particles mixes before test fully.

Centrifugal retention volume (CRC)

The centrifugal retention volume of super-absorbent is measured through standard method of test No.WSP 241.5-05 " Centrifuge Retention Capacity ".

0.3psi the absorption value under the load (AUL0.3psi)

The absorption value of super-absorbent under 2068Pa (0.3psi) load measured through standard method of test No.WSP 242.2-05 " Absorption under pressure ".

0.7psi the absorption value under the load (AUL0.7psi)

The absorption value of super-absorbent under 4826Pa (0.7psi) load is similar to standard method of test No.WSP 242.2-05 " Absorption under pressure " and measures, and difference is to use 49g/cm ²Weight (produce 0.7psi load) rather than 21g/cm ²Weight (produce 0.3psi load).

Salt solution water conservancy diversion rate (SFC)

As described in EP 0 640 330 A1; Absorb liquid and the salt solution water conservancy diversion rate of the swell gel layer that the forms gel coat rate of permeation as the swell gel layer of superabsorbent particles under the pressure of 0.3psi (2068Pa) is measured by super-absorbent; To improving with the device described in Fig. 8 at the 19th page of above-mentioned patented claim; So that do not use frit (glass frit) (40), plunger (39) is by the hole of forming and comprise now 21 equally distributed same sizes in entire contact surface is long-pending with the identical polymer materials of cylinder (37).The process of measuring and the assessment and EP 0 640 330 A1 of measuring result are remained unchanged.Automatically detect flow.

Salt solution water conservancy diversion rate (SFC) is calculated as follows:

SFC[cm ³s/g]＝(Fg(t＝0)xL0)/(dxAxWP)，

Wherein Fg (t=0) is the flow in the NaCl solution of g/s, and the linear regression analysis of Fg (t) data that its use traffic is measured obtains through being extrapolated to t=0; L0 is the thickness in the gel coat of cm; D is with g/cm ³The density of the NaCl solution of meter; A is with cm ²The area of the gel coat of meter; WP is with dyn/cm ²Static pressure on the gel coat of meter.

Free swell gel bed rate of permeation (FSGBP)

The said mensuration of [0061] to [0075] section among rate of permeation such as US 200,5/0 256 757 A1.

The regain of hydrogel (residual regain, water ratio)

The water ratio of water-absorbing polymer particles is measured through standard method of test No.WSP 230.2-05 " Moisture content ".

Mean particle size

The mean particle size of product part is measured through standard method of test No.WSP 220.2-05 " Particle size distribution ".

The CIE chromatic number (L, a, b)

Color analysis uses " LabScan XE S/N LX17309 " according to CIELAB method (Hunterlab rolls up the 8,1996,7th, 1 to 4 page), and (HunterLab, Reston U.S.A.) carry out tintometer.This method is described color through coordinate L, a and the b of three-dimensional system.L representes brightness, and wherein L=0 representes that black and L=100 represent white.The numerical value of a and b is represented the position of said color on red/green and yellow/blue axle respectively, wherein+a represent red ,-a represent green ,+b represent yellow and-b represents blueness.The HC60 value is calculated through formula HC60=L-3b.

Said color measuring is corresponding to three zones (three-area) method according to DIN 5033-6.

Weathering test

Measure 1 (priming color): interior diameter is the superabsorbent particles that overfill is housed in the vinyl disc of 9cm, subsequently it is flattened measurement CIE chromatic number and HC60 value along the edge with blade.

Measure 2 (aging backs): interior diameter is in the vinyl disc of 9cm superabsorbent particles to be housed, and subsequently it is flattened along the edge with blade.Then said plate opening is placed constant relative air humidity with 86% and the weather controlling box that is heated to 60 ℃.After 21 days, plate is taken out.After being cooled to room temperature, measure the CIE chromatic number.

Embodiment:

General (general) method I: drying composite

Component to be mixed is packed in the polyethylene specimen bottle (capacity 500ml) and with drum tumbler (model T2C; Willy A.Bachofen AG Maschinenfabrik, Basle; Switzerland) thorough mixing is 15 minutes.

Universal method II: wet mixing

With super-absorbent at

colter formula mixing machine (manufacturers: Gebr.

Maschinenbau GmbH; Elsener-Strasse 7-9; 33102 Paderborn, Germany; Model M5) in the axle speed of room temperature and 250 rev/mins down through two substance nozzle usefulness separately the concrete solution of specified amount be coated with.After the spray application, be blended in 80 rev/mins axle speed down a continuation carried out again 15 minutes, with product in vacuum drying chamber 80 ℃ with the pressure of 250mbar drying 60 minutes down, and remove agglomerate through the screen cloth of 850 μ m.

Embodiment 1 to 15 employed base-material is the commercially available super-absorbent that gets

B 7055 (BASF SE; Ludwigshafen, Germany).

Embodiment 1

According to universal method I;

B 7055 of 100g is mixed with the 2,6 di tert butyl 4 methyl phenol of 0.050g.

Embodiment 2

According to universal method I;

B 7055 of 100g and two [single ethyl (3,5-di-t-butyl-4-hydroxybenzene methyl) phosphonic acids] calcium of 0.060g are mixed.

Embodiment 3

According to universal method I; With

B 7055 and 3 of 0.075g of 100g, 5-di-tert-butyl-hydroxy phenyl propionic acid mixes.

Embodiment 4

According to universal method I; With

B 7055 and 4 of 0.100g of 100g, the 4-thiobis (the 6-tertiary butyl--cresols) mix.

Embodiment 5

According to universal method I;

B 7055 of 100g and the tetramethylolmethane four (3-(3, the 5-di-tert-butyl-hydroxy phenyl) propionic ester) of 0.040g are mixed.

Embodiment 6

According to universal method I;

B 7055 of 100g is mixed with 3-(3, the 5-di-tert-butyl-hydroxy phenyl) the propionic acid stearyl of 0.130g.

Embodiment 7

According to universal method I; With B 7055 and 4 of 0.050g of 100g, two (dodecyl sulphomethyl) ortho-cresols of 6-mix.

Embodiment 8

According to universal method I, with B 7055 and 3,3 ', 3 ' of the 0.070g of 100g; 5,5 ', 5 '-six tertiary butyls-α; α ', α '-(1,3; 5-Three methyl Benzene-2,4,6-three bases) three p-cresol mix.

Embodiment 9

According to universal method I; With

B 7055 of 100g and the N of 0.050g; N-hexane-1; 3-two bases two (3-(3,5-di-tert-butyl-hydroxy phenyl propionic acid amide)) mix.

Embodiment 10

According to universal method I;

B 7055 of 100g and three (2, the 4-di-tert-butyl-phenyl) phosphorous acid ester of 0.050g are mixed.

Embodiment 11

According to universal method I;

B 7055 and 3 of 0.060g with 100g; Two (the octadecyl oxygen bases)-2,4,8 of 9-; 10-four oxa-s-3,9-two phospha spiral shell [5.5] undecanes mix.

Embodiment 12

According to universal method I;

B 7055 of 100g and two (2, the 4-di-tert-butyl-phenyl) pentaerythritol diphosphites of 0.040g are mixed.

Embodiment 13

According to universal method II; The methanol solution of two [single ethyl (3, the 5-di-t-butyl-4-hydroxybenzene methyl) phosphonic acids] calcium of the 4.0 weight % of

B 7055 usefulness, 1.5 weight %---based on amount meter of super-absorbent---is coated with.

Embodiment 14

According to universal method II; The aqueous isopropanol of 2.5 weight % three (2, the 4-di-tert-butyl-phenyl) phosphorous acid ester of

B 7055 usefulness, 2.0 weight %---based on amount meter of super-absorbent---is coated with.

Embodiment 15

According to universal method II, with the 40 weight % ethylenebis (oxygen base ethylidene) of

B 7055 usefulness, 0.5 weight %---based on amount meter of super-absorbent---two-3-(5-tertiary butyl-4-hydroxy--tolyl) propionic ester) aqueous dispersion be coated with.Different with universal method II is that product does not carry out drying, but after mixing, directly screens out.

The super-absorbent through coating of preparation carries out weathering test thus.The result lists in the table 1.Said embodiment shows super-absorbent of the present invention, and obviously color is more shallow and more not easy to change in aging back.

Table 1

Embodiment C 16 (contrast)

At first, in the stainless steel vessel of 2l, pack into sodium hydroxide solution and the freezing deionized water of 675g of 326.7g 50 weight %.Under agitation add 392.0g vinylformic acid, the speed of in this process, regulating interpolation is so that temperature is no more than 35 ℃.Under agitation mixture is cooled off then by means of cooling bath.When the temperature of mixture is reduced to 20 ℃; The triacrylate (

PO 9044V, the BASF SE that add 1.08g triethoxy glycerine; Ludwigshafen; Germany), 0.041g 2-hydroxy-2-methyl-1-phenyl third-1-ketone (

1173; Ciba Specialty Chemicals Inc.; Basle, Switzerland) with 0.014g 2,2-dimethoxy-1; 2-phenylbenzene second-1-ketone (

651; Ciba Specialty Chemicals Inc., Basle, Switzerland).Mixture is further cooled off, when reaching 15 ℃, feed nitrogen and make mixture oxygen-free gas via frit.When reaching 0 ℃, add 0.51g Sodium Persulfate (being dissolved in the 5ml water) and 0.06g hydrogen peroxide (being dissolved in the 6ml water), monomer solution is transferred in the glass disc.This glass disc is of a size of and makes that the layer thickness of monomer solution is 5cm.Subsequently; Add and be dissolved in the following mixture of 0.047g in the 5ml water: the disodium salt of the sodium salt of 2-hydroxyl-2-sulfino acetate, 2-hydroxyl-2-sulfonic group acetate and sodium sulfite anhy 96 (

FF6; L.Br ü ggemann KG; Salzstrasse 131; 74076 Heilbronn, Germany), monomer solution simply stirs by means of glass stick.The glass disc that will comprise monomer solution places (uv intensity=25mW/cm under the uv lamp ²), polymerization begins in this process.After 16 minutes, the gel that obtains is pulverized three times by means of the commercially available mincer with 6mm porous disc, and following dry one hour at 160 ℃ in the loft drier of laboratory.Then product is ground and obtains the sieve fraction of 150-850 μ m.

Carrying out surface back when crosslinked; Said stock polymer is being furnished with

mixing machine of heating jacket (manufacturers: Gebr.

Maschinenbau GmbH; Elsener-Strasse 7-9; 33102 Paderborn, Germany; Model M5) in; In the axle speed of room temperature and 450 rev/mins down through pair substance nozzle; Ethylene glycol diglycidylether (

EX-810 with 0.10 weight %; Available from Nagase ChemteX Corporation, Osaka, Japan), 1.50 weight % 1; The mixture of the aluminum sulfate aqueous solution of the water of 2-Ucar 35,2.8 weight % and 0.4 weight % (26.8 weight %) is coated with, and each value is based on the stock polymer meter.

After the spray application, the product temperature rises to 150 ℃, reaction mixture is remained on following 60 minutes of the axle speed of this temperature and 80 rev/mins.The product that generates is cooled to room temperature once more and sieves.Crosslinked super-absorbent is that the sieve fraction of 150 μ m to 850 μ m obtains as granularity behind the surface.

Embodiment 16 to 20

According to universal method I; Super-absorbent and hydrophobic precipitated silica (

D-17 of 0.15g of separately 150g being obtained by Embodiment C 16; Evonik Degussa GmbH; Frankfurt am Main; Germany) and quantitative two [single ethyl (3, the 5-di-t-butyl-4-hydroxybenzene methyl) phosphonic acids] calcium of following table 2 middle fingers mix.

The super-absorbent through coating of preparation is thus carried out weathering test.The result lists in the table 2.Even said embodiment is presented in the weathering process a spot of stablizer and also can stablizes super-absorbent of the present invention and suppress variable color.

Table 2

^*) separately based on the amount of super-absorbent meter;

^*) priming color L=88.7; A=-0.4; B=9.0; HC60=61.7

Embodiment 21 to 25

According to universal method I; Super-absorbent and hydrophobic precipitated silica (

D-17 of 0.15g of separately 150g being obtained by Embodiment C 16; Evonik Degussa GmbH; Frankfurt am Main; Germany) and following table 3 middle fingers quantitative three (2, the 4-di-tert-butyl-phenyl) phosphorous acid ester mix.

The super-absorbent through coating of preparation is thus carried out weathering test.The result lists in the table 3.Even said embodiment is presented in the weathering process a spot of stablizer and also can stablizes super-absorbent of the present invention and suppress variable color.

Table 3

^*) separately based on the amount of super-absorbent meter;

^*) priming color L=88.7; A=-0.4; B=9.0; HC60=61.7

Embodiment 26

Repeat Embodiment C 16, different is in further being cooled to 15 ℃ of forward direction monomer solutions, to add two [single ethyl (3, the 5-di-t-butyl-4-hydroxybenzene methyl) phosphonic acids] calcium of 0.59g in addition.

Embodiment 27

Repeat Embodiment C 16, different is in process of lapping, in gel, to add two [single ethyl (3, the 5-di-t-butyl-4-hydroxybenzene methyl) phosphonic acids] calcium of 0.59g.

The super-absorbent of preparation is thus carried out weathering test.The result lists in the table 4.Even said embodiment is presented in the weathering process a spot of stablizer and also can stablizes super-absorbent of the present invention and suppress variable color.

Table 4

^*) separately based on the amount of super-absorbent meter;

^*) priming color L=88.7; A=-0.4; B=9.0; HC60=61.7

Embodiment C 28 (contrast)

Triacrylate ( PO 9044V, BASF SE with the triethoxy glycerine of the deionized water of the vinylformic acid of the sodium acrylate aqueous solution (deionized water solutions of 37.5 weight %) of 14.3kg, 1.4kg and 350g and 18.5g; Ludwigshafen Germany) mixes.This solution is being full of (180 ℃ in the dropping liquid tower (dropletization tower) through heating of nitrogen atmosphere; High 12m, diameter 2m, gas velocity 0.1m/s in the concurrent; Liquid-drop machine diameter 40mm; In high 2mm, the drip tray that to contain 60 diameters be the hole of 200 μ m) in carry out dropping liquidization with the speed of 32kg/h, its temperature is 25 ℃ in this process.Only, monomer solution is mixed with two kinds of initiator solutions through static mixer at the upper reaches of liquid-drop machine.Employed initiator 1 is 2 of 3 weight %, the deionized water solution of two [2-(2-tetrahydroglyoxaline-2-yl) propane] dihydrochlorides of 2 '-azo; The deionized water solution of peroxo-two sodium sulfate that employed initiator 2 is 6.1 weight %.The speed that is metered into of initiator solution 1 is 1.462kg/h; The speed that is metered into of solution 2 is 0.629kg/h.The polymer beads that generates is sieved any agglomerate that forms to remove.The sieve fraction of 150 to 850 μ m obtains as product.

Embodiment 28

According to universal method I, 100g is mixed by the tetramethylolmethane four (3-(3, the 5-di-tert-butyl-hydroxy phenyl) propionic ester) of super-absorbent that obtains in the Embodiment C 28 and 0.10g.

Embodiment 29

According to universal method I, 100g is mixed by three (2, the 4-di-tert-butyl-phenyl) phosphorous acid ester of super-absorbent that obtains in the Embodiment C 28 and 0.10g.

Embodiment 30

According to universal method I, 100g is mixed by the tetramethylolmethane four (3-(3, the 5-di-tert-butyl-hydroxy phenyl) propionic ester) of super-absorbent that obtains in the Embodiment C 28 and 0.05g and three (2, the 4-di-tert-butyl-phenyl) phosphorous acid ester of 0.05g.

The super-absorbent of preparation carries out weathering test thus.The result lists in the table 5.This embodiment shows super-absorbent of the present invention, and obviously color is more shallow and more not easy to change in aging back.Yet it shows that also mixture can work synergistically.

Embodiment C 31 (contrast)

Triacrylate (

PO 9044V, BASF SE with the triethoxy glycerine of the deionized water of the vinylformic acid of the sodium acrylate aqueous solution (deionized water solutions of 37.5 weight %) of 14.3kg, 1.4kg and 350g and 6.6g; Ludwigshafen Germany) mixes.This solution is being full of (180 ℃ in the dropping liquid tower through heating of nitrogen atmosphere; High 12m, diameter 2m, gas velocity 0.1m/s in the concurrent; Liquid-drop machine diameter 40mm; In high 2mm, the drip tray that to contain 60 diameters be the hole of 200 μ m) in carry out dropping liquidization with the speed of 32kg/h, its temperature is 25 ℃ in this process.Only, monomer solution is mixed with three kinds of initiator solutions through static mixer at the upper reaches of liquid-drop machine.Employed initiator 1 is 2 of 3 weight %, the deionized water solution of two [2-(2-tetrahydroglyoxaline-2-yl) propane] dihydrochlorides of 2 '-azo; The deionized water solution of peroxo-two sodium sulfate that employed initiator 2 is 6.1 weight %; Employed initiator 3 is the deionized water solution of the xitix of 3 weight %.The speed that is metered into of initiator solution 1 is 0.548kg/h; The speed that is metered into of solution 2 is 0.449kg/h; The speed that is metered into of solution 3 is 0.183kg/h.The polymer beads that generates is sieved any agglomerate that forms to remove.The sieve fraction of 150 to 850 μ m obtains as product.

Embodiment C 32 (contrast)

Triacrylate (

PO 9044V, BASF SE with the triethoxy glycerine of the deionized water of the vinylformic acid of the sodium acrylate aqueous solution (deionized water solutions of 37.5 weight %) of 14.3kg, 1.4kg and 350g and 6.6g; Ludwigshafen Germany) mixes.This solution is being full of (180 ℃ in the dropping liquid tower through heating of nitrogen atmosphere; High 12m, diameter 2m, gas velocity 0.1m/s in the concurrent; Liquid-drop machine diameter 40mm; In high 2mm, the drip tray that to contain 60 diameters be the hole of 200 μ m) in carry out dropping liquidization with the speed of 32kg/h, its temperature is 25 ℃ in this process.Only, monomer solution is mixed with three kinds of initiator solutions through static mixer at the upper reaches of liquid-drop machine.Employed initiator 1 is 2 of 3 weight %, the deionized water solution of two [2-(2-tetrahydroglyoxaline-2-yl) propane] dihydrochlorides of 2 '-azo; The deionized water solution of peroxo-two sodium sulfate that employed initiator 2 is 6.1 weight %; The sodium salt of the 2-hydroxyl that employed initiator 3 is 3 weight %-2-sulfino acetate, the 2-hydroxyl-disodium salt of 2-sulfonic group acetate and the mixture of sodium sulfite anhy 96 (

FF7; L.Br ü ggemann KG; Salzstrasse 131; 74076 Heilbronn, deionized water solution Germany).The speed that is metered into of initiator solution 1 is 0.548kg/h; The speed that is metered into of solution 2 is 0.449kg/h; The speed that is metered into of solution 3 is 0.183kg/h.The polymer beads that generates is sieved any agglomerate that forms to remove.The sieve fraction of 150 to 850 μ m obtains as product.

Embodiment 31

According to universal method I, 100g is mixed by two [single ethyl (3,5-di-t-butyl-4-hydroxybenzene methyl) phosphonic acids] calcium of super-absorbent that obtains in the Embodiment C 31 and 0.10g.

Embodiment 32

According to universal method I, 100g is mixed by (3,5-di-t-butyl-4-hydroxybenzene methyl) diethyl phosphonate of super-absorbent that obtains in the Embodiment C 32 and 0.10g.

The super-absorbent of preparation carries out weathering test thus.The result lists in the table 6.This embodiment shows super-absorbent of the present invention, and obviously color is more shallow and more not easy to change in aging back.

Embodiment C 33 (contrast)

At first be

pedal-type dryer (manufacturers: Gebr.

Maschinenbau GmbH of 5l at the capacity of being furnished with heating/cooling jacket; Elsener-Strasse 7-9; 33102 Paderborn, Germany; Model VT 5R-MK) pack in sodium acrylate solution (the 100mol% neutral vinylformic acid of 37.3 weight % of 478g water, 244.3g vinylformic acid, 1924.9g; Promptly do not contain free vinylformic acid or free sodium salt), triacrylate (

PO 9044V, the BASF SE of 16.0g lime carbonate and 2.52g triethoxy glycerine; Ludwigshafen, Germany), and through making its inerting in 20 minutes with nitrogen jet.The axle of reactor drum is with 96 rev/mins of rotations consistently.Simultaneously, make initiator subsequently add down from the externally cooled reaction mixture at about 20 ℃.At last, under agitation promptly the aqueous hydrogen peroxide solution of 2.139g Sodium Persulfate (being dissolved in 12.12g water), 0.046g xitix (being dissolved in 9.12g water) and 0.127g30 weight % (with the dilution of 1.15g water) is in turn added in the kneader.Beginning, when internal temperature reached 30 ℃, chuck heated so that reaction is carried out with very sufficient adiabatic method fully through 80 ℃ of heat-carrying agent mediums with being swift in response.When reaching maximum temperature, reactor drum cools off (12 ℃ cooling fluids) once more, makes the gel that forms be cooled to below 50 ℃, subsequently with its discharge.Said then gel is following dry one hour at 160 ℃ in the loft drier of laboratory.Then product is ground and obtains the sieve fraction of 150-700 μ m.

Carrying out surface back when crosslinked; Said stock polymer is being furnished with

colter formula mixing machine of heating jacket (manufacturers: Gebr.

Maschinenbau GmbH; Elsener-Strasse 7-9; 33102 Paderborn, Germany; Model M5) in; In the axle speed of room temperature and 450 rev/mins down through pair substance nozzle; With 1 of the water of N-(2-hydroxyethyl)-2-oxazolidone of 0.125 weight %, 1.5 weight %, 1.5 weight %; The mixture of the 25 weight % Aluctyl aqueous solution of the anhydrous sorbitol list cocounut oil acid esters of ammediol, 0.003 weight % ("

20 ") and 2.8 weight % is coated with, and each value is based on the stock polymer meter.After the spray application, the product temperature rises to 150 ℃ and reaction mixture in the maintenance 80 minutes down of the axle speed of this temperature and 80 rev/mins.The product that obtains is cooled to room temperature once more and sieves.Crosslinked super-absorbent is that the sieve fraction of 150 μ m to 710 μ m obtains as granularity behind the surface.

Embodiment 33

According to universal method I, by 2 of super-absorbent that obtains in the Embodiment C 26 and 0.050g, 2 '-ethylenebis [4, two (1, the 1-dimethyl ethyl) phenol of 6-] is mixed with 100g.

Embodiment 34

Repeat Embodiment C 33, different is behind the surface, in the cross-linking process stock polymer to be used three (2, the 4-di-tert-butyl-phenyl) phosphorous acid ester coating based on 0.2 weight % of stock polymer meter in addition.

Embodiment 35

Repeat Embodiment C 33 (contrast); Different is in polymerization process;, the internal temperature of reaction mixture in

pedal-type dryer also adds 1.2g tetramethylolmethane four (3-(3, the 5-di-tert-butyl-hydroxy phenyl) propionic ester) when reaching 60 ℃.

The super-absorbent of preparation carries out weathering test thus.The result lists in the table 7.This embodiment shows super-absorbent of the present invention, and obviously color is more shallow and more not easy to change in aging back, and can the impair absorption performance.

Claims (11)

1. super-absorbent that comprises the stablizer of at least a inhibition variable color, said stablizer is selected from phenol, (HP (O) (OH) for phosphonic acids ₂), phosphorous acid (H ₃PO ₃) and these sour salt and esters.

2. the super-absorbent of claim 1, it comprises calcium, strontium or barium.

3. claim 1 or 2 super-absorbent, it also comprises at least a compound and/or at least a water-fast inorganic particulate solid that is selected from sulfinate derivant.

4. the super-absorbent of claim 1 to 3, it comprises crosslinked, the part neutral polymkeric substance of at least a ethylenically unsaturated monomers that contains at least one acidic group.

5. each super-absorbent in the claim 1 to 4, wherein said monomer is a vinylformic acid.

6. each super-absorbent in the claim 1 to 5, it is that the back, surface is crosslinked.

7. each super-absorbent in the claim 1 to 5, said stablizer adds wherein with main insoluble form.

8. a method for preparing the super-absorbent that claim 1 to 7 limits wherein is selected from phenol, phospho acid (H ₃PO ₂), (HP (O) (OH) for phosphonic acids ₂), phosphorous acid (H ₃PO ₃) and the stablizer of the inhibition variable color of these sour salt and ester in the preparation process of super-absorbent or join wherein afterwards.

9. the method for claim 8, wherein said stablizer adds with main insoluble form.

10. goods that are used for absorption fluids, it comprises a kind of super-absorbent that claim 1 to 7 limits.

11. a method for preparing the goods that are used for absorption fluids, it is included in and uses the super-absorbent that claim 1 to 7 limited in the preparation.