CN100411691C

CN100411691C - Swellable hydrogel-forming polymers having a low fine dust concentration

Info

Publication number: CN100411691C
Application number: CNB2004800380861A
Authority: CN
Inventors: U·里格尔; T·丹尼尔; M·魏斯曼特尔; M·埃利奥特; D·赫尔梅林
Original assignee: BASF SE
Current assignee: BASF SE
Priority date: 2003-12-19
Filing date: 2004-12-17
Publication date: 2008-08-20
Anticipated expiration: 2024-12-17
Also published as: CN1897988A; DE10360394A1

Abstract

Disclosed are a swellable hydrogel-forming polymer containing at least one hydrophilic polymer with a dendritic structure, a method for producing said swellable hydrogel-forming polymer, and the use thereof in hygiene articles.

Description

Polymer, the Preparation Method And The Use of the formation hydrogel of swellable and the hygienic articles that comprises this polymer

The present invention relates to have the polymer of formation hydrogel of the swellable of low fine content, a kind of preparation has the method for polymer of formation hydrogel of swellable of low fine content and their purposes.

The polymer of the formation hydrogel of swellable is known by prior art, is called super absorbent polymer (SAP) or abbreviates superabsorbents as.

The polymer of the formation hydrogel of swellable especially for example (is total to) polymer of polymeric hydrophilic monomer, grafting (be total to) polymer of one or more hydrophilic monomers on suitable graft bases, crosslinked cellulose ether, crosslinked starch ether, crosslinked carboxymethyl cellulose, partial cross-linked polyoxyalkylene or can be in aqueous fluids swollen natural prodcuts such as guar gum derivatives. this class hydrogel is used for preparing diaper as the product that can absorb aqueous solution, tampon, cotton wool and other hygienic articles, also be used for the market garden or be used for thickening various refuses, especially clinical waste as water-retaining agent.

Based on used polymer, the polymer of the formation hydrogel of swellable preferably can absorb at least 10 times of their own wts, 0.9 preferred 20 times weight % sodium chloride solution. preference as in addition under the pressure of 0.7psi, also can obtain this absorption.

Usually make behind the polymer surfaces of formation hydrogel of swellable or the gel crosslinked to improve their performance characteristic. this back is crosslinked itself be known by those of ordinary skill in the art and preferably aqueous gel carry out in mutually or as make substrate and fractionated polymer beads surface after crosslinked.

Superabsorbents carries out milled processed in the preparation and the course of processing, and cause that there is the granule of abate in the corner, this has produced fine powder or fines. and the fine powder of generation causes the problem that plugged filter, viscous precipitate, caking and transmission superabsorbents obviously have. and the high surface area of powder causes from environment fast Absorption moisture and the precipitation powder is become sticky, this causes the pollution of production equipment. in addition, in pneumatic transmission system, form the hard caking of powder. in addition, hygienist and professional doctor's utmost point do not wish that thin triturate is arranged.

Unless fine powder is isolated especially, otherwise it will be in preparation during superabsorbents or throw into question before polymer is introduced hygienic articles, and the saline flow conductivity (SFC) when reducing gel greatly and using. this causes that breakthrough rate increases then.

Therefore, be used for the dust separating method of superabsorbents, propose among WO-A-94/22940 and the EP-A-0 679 678 at patent application WO-A-92/13912.

WO-A-92/13912 and WO-A-94/22940 have described by making the superabsorbents dedusting with the Polyethylene Glycol surface applied. and the disadvantage of Polyethylene Glycol is that they are linear water-soluble polymers, they have increased the viscosity around gel particle solution greatly, therefore reduced the flowability of solution. when using in hygienic articles, this causes in the swell gel saline flow conductivity (SFC) poor.

EP-A-0679678 has described a kind of wherein by reduce the method for powdery superabsorbents content of powder with the polysiloxanes post processing. and this list of references for example also advises using other dedusting agent such as Polyethylene Glycol and polyglycol ether. and polysiloxanes has undesirable hydrophobic interaction to superabsorbents, and this has reduced their swelling rate.

Yet EP-A-0755964 has described the surface applied of the superabsorbents that uses insoluble wax., the wax that uses in some cases to superabsorbents have hydrophobic interaction and not used additives be difficult to disperse. but have the surface activity feature as the conventional dispersant of auxiliary agent usually for this reason and reduced the surface tension of the liquid that falls into hygienic articles, this can cause seepage again.

US 5,641,561 and US 5,589,256 have described and use suitable polymerization and non-polymeric binding agent that superabsorbent particles is adhered on the fiber. in hygienic articles, binding agent should adhere to superabsorbent particles on the fiber by hydrogen bond. do not mention binding agent, especially for the saline flow conductivity of disclosed polymeric binder to swell gel, perhaps fall into the possible adverse effect of the surface tension of liquid of hygienic articles, any solution of these problems is not disclosed yet. in addition, it must be emphasized that for non-polymeric binding agent, because their permeation and they are to the influence of skin in use, not to wish very much these in hygienic articles as solvent. when openly not being taught in dedusting and adhering to granule on the fiber, make these solvents reduce to minimum.

Therefore, the purpose of this invention is to provide the method for polymer of formation hydrogel that a kind of preparation is called the swellable of superabsorbents, wherein obtained having the superabsorbents of low fine content, and compared with untreated superabsorbents, swellability and saline flow conductivity all do not have variation.

Another object of the present invention is the method for polymer that a kind of formation hydrogel for preparing swellable is provided, if wherein be exposed to mechanical stress fully, the fine powder content of gained superabsorbents only slightly increases. fine powder is meant the granule of diameter less than 10 μ m.

Another object of the present invention wherein use Powdered and/or powder additive post processing superabsorbents, and wherein superabsorbents has low fine content for a kind of method for preparing superabsorbents is provided.

Another object of the present invention is for providing a kind of method for preparing superabsorbents, wherein obtained having the superabsorbents of optimal transmission performance. for example in order to make them can be easy to be metered into the transmission screw rod, especially under high relative humidity, do not increase the tendency of any caking, should have certain viscosity at this superabsorbents that obtains.

We have found that these purposes realize surprisingly by the hydrophilic polymer that uses dendritic structure in the polymer of the formation hydrogel for preparing swellable, wherein superabsorbents especially has low fine content after being exposed to mechanical stress, the ability of improved adhesive powder shape and/or powder additive, high swelling rate, haline water flow conductivity and optimal flow characteristic.

Dendritic exists

Lexikon-Chemie, Georg Thieme Verlag, Stuttgart, the 10th edition, be defined as in the 898th page by on the monomer that connects before each, progressively connect two or more monomers at every turn, make per step of number of monomer end group be all that Exponential growth produces spherical tree at last and the synthetic macromolecule of constructing.

For the purpose of the present invention, the hydrophilic polymer of useful dendritic structure is for having 8 or more a plurality of, and preferred 16 or more a plurality of, the more preferably polyhydric alcohol of 32 or more a plurality of hydroxyls, and preferably 14 times of branching or more, more preferably 30 times or more non-linear skeleton.

The hydrophilic polymer of dendritic structure for example comprises by using C ₃-C ₂₀Hydroxy carboxylic acid is preferably used C ₄-C ₁₂Hydroxy carboxylic acid is more preferably used C ₅-C ₈Hydroxy carboxylic acid makes the polyhydric alcohol esterification and the polyester that obtains, wherein hydroxy carboxylic acid comprises at least two hydroxyls, preferred two hydroxyls and/or at least two carboxyls. especially preferably have the hydroxy carboxylic acid of two hydroxyls and a carboxyl, especially 2, the 2-dihydromethyl propionic acid. polyhydric alcohol is the chemical compound with at least two hydroxyls, example is an ethylene glycol, diethylene glycol, 2,2'-ethylenedioxybis(ethanol)., Polyethylene Glycol, propylene glycol, dipropylene glycol, tripropylene glycol, polypropylene glycol, butanediol, 1, ammediol, 1, the 4-butanediol, bisphenol-A, glycerol, trimethylolpropane, tetramethylolmethane and/or Sorbitol. preferred dendritic polyester, preferred especially

20,

30,

40 Hes

310 (Perstorp Specialty Chemicals AB, Sweden).

For the purpose of the present invention, the hydrophilic polymer of useful dendritic structure also comprises can be by making the polyol condensating with at least three hydroxyls, and alkoxylate and the polymer that obtains subsequently. the example of these polymer is for can be by making the glycerol molecule condensation, and ethoxylation subsequently and the polyethylene glycol that obtains.

For the purpose of the present invention, the hydrophilic polymer of useful dendritic structure also comprises can be by making the monomer addition polymerization with at least one hydroxyl, and alkoxylate and all polymer of obtaining subsequently. addition polymerization preferably carries out in the presence of cross-linking agent. because numerous hydroxyls from the teeth outwards, this has obtained having the polymer beads of water-wetted surface. for example, so-called star Polyethylene Glycol can be according to Makromol.Chem.189,2885 (1988) by making the polymerization of hydroxyethylbenzene ethylene free radical, and alkoxylate and obtaining subsequently.

Other example of useful polymer is according to the present invention

And Astramol

(DSM N.V., Holland) highly-branched polymers. they for example especially comprise and can repeat the highly branched polypropylen imine that multiple Michael addition and hydrogenation obtain by making butanediamine and acrylonitrile, the star polycaprolactone, the star nylon-6, for example be the highly branched polyesteramide of the addition compound product of 1: 1 succinic anhydrides and diethanolamine based on mol ratio. the inventive method also can use so-called PAMAM dendritic based on polyamide-amide to carry out, and this dendritic for example can obtain by making ammonia and acrylic acid methyl ester. and ethylenediamine repeat multiple reaction.

Can use polyglycereol, star Polyethylene Glycol and other hydrophilic compounds, but the polyhydric alcohol of preferred sphere or cumulus shape (cumulus-shaped) isomolecule geometry.

Preference such as glass transition temperature T _gBe 20-100 ℃, more preferably 25-50 ℃ and/or mean molecule quantity are 1000-10000g/mol, more preferably the hydrophilic polymer of the dendritic structure of 2000-6000g/mol.

In the methods of the invention, the consumption of the hydrophilic polymer of dendritic structure is preferably 0.005-10 weight % based on the polymer of the formation hydrogel of swellable, more preferably 0.01-5 weight %, even more preferably 0.05-1 weight %, especially 0.10-0.80 weight %.

Preferably the hydrophilic polymer with dendritic structure mixes with exsiccant water absorption hydrogel. and drying is meant that preferred water content is less than 20 weight %, be more preferably less than 10 weight %. but also can before the crosslinked operation behind the surface, among and/or afterwards, the hydrophilic polymer of dendritic structure is added the polymer of the formation hydrogel of swellable, but preferably behind the surface, adds in the crosslinked operating process.

Blended mode is not carried out any restriction, but preferably use reaction mixer or mixing and drying baker, for example

Blender,

Blender,

Blender,

Blender,

Exsiccator and

In addition, also can use fluidized bed dryer. advantageously used 1-180 minute, preferred 5-20 minute the time of staying and 25-375rpm, the speed of preferred 100-150rpm is mixed.

When crosslinker solution uses behind the surface, cross-linking agent behind the surface can be used in solution with dendritic; Perhaps can independent liquid stream be spurted in the crosslinked blender in back by independent nozzle. when the additive used with powder or powder type, also dendritic can be dissolved in powdery wherein or Powdered additive and also can be scattered in wherein the solvent. this mixture also can be chosen wantonly and comprise back, surface cross-linking agent.

Useful solvent comprises and is used for all crosslinked conventional solvents of surface back. special preferred water, also preferred 1,2-propylene glycol, 1, ammediol, 1, yet 4-butanediol, isopropyl alcohol, ethanol, methanol, ethylene carbonate, propylene carbonate, glycerol and composition thereof. the mixture of special preferred water and one or more above-mentioned organic solvents., choice of Solvent determines and is not limited to above-mentioned solvent by the requirement that causes effectively preparing solution.

Can in solvent, choose wantonly and add one or more surfactants or dispersant. can preferably add non-ionic surface active agent for example sorbitan monolaurate (Span 20), anhydrosorbitol list dodecanoate, anhydrosorbitol list Palmitate, anhydrosorbitol monooctadecyl acid ester, dehydrating sorbitol monooleate, sorbitan sesquioleate, anhydrosorbitol trioleate, it can trade name Span40, Span60, Span80, Span83, Span85 obtain.

Yet, the preferred surfactant that in solution, does not add as dispersing aid.

Can choose wantonly and comprise one or more dispersive powderies or Powdered additive, can choose wantonly and comprise dispersing aid, also can choose the soluble metallic salt that comprises aluminum sulfate or some other 3 valencys or 4 valency metals wantonly, and can choose the dendritic solution that comprises at least a surface back cross-linking agent or dispersion wantonly preferably by with dendritic fusion (if necessary) and will melt body and inject solvent or inject partial solvent and dilute with another part subsequently and prepare. preferred operations is attended by abundant stirring, more preferably turbulences, for example use Ultraturax. or also can be with directly fusion in hot solvent or portion of hot solvent of dendritic. in addition, also can for example use ultrasonic or suitable nozzle dispersion dendritic.

When also disperseing powdery or Powdered additive, preferably use suitable continuous mixing device or batch mixer to prepare dispersion especially. especially preferably from IKA-Werke GmbH; The blender of the called after MHD 2000/4 of CoKG, MHD 2000/5 and CMS 2000/4. can certainly use the blender of like configurations and other structure. can also use the grinding pump described in DE10131606, for example the NEWX80-50-315 from Wernert-Pumpen GmbH prepares dispersion.

Under specific situation, also can prepare dispersion by the ultrasonication of operation in batches or continuously. can also use common conventional wet grinding to prepare dispersion. stir or do not stir the fine particle wet chemistry precipitation that makes chemical reaction between the soluble component during also especially preferably by heating. this produces precipitate in small, broken bits especially usually.

The present invention further provides the polymer of formation hydrogel that can swellable obtained by the method for the present invention, especially comprise less than 100 ppm by weight, preferably less than 50 ppm by weight, be more preferably less than the polymer of the diameter of 10 ppm by weight less than the formation hydrogel of the particulate swellable of 10 μ m, and they are at absorbing blood and/or body fluid, especially the purposes in the urine.

The present invention further provides the polymer of formation hydrogel that can swellable obtained by the method for the present invention, especially comprise less than 100 ppm by weight, preferably less than 50 ppm by weight, be more preferably less than the polymer of the diameter of 10 ppm by weight less than the formation hydrogel of the particulate swellable of 10 μ m, wherein the polymer of the formation hydrogel of swellable comprises at least a Powdered and/or powder additive, for example slaine such as aluminum sulfate and/or magnesium sulfate, the pyrolysismethod silicon oxide as

200, polysaccharide and derivant thereof, non-ionic surface active agent, wax, kieselguhr and/or tiny balloon, and they are at absorbing blood and/or body fluid, the purposes in especially urinating.

Tiny balloon is described in Chem.Ing.Techn.75, in 669 (2003). tiny balloon is that diameter is the inflation of 1-1000 μ m or the globular solids granule of finding time. the 1-10%. that their wall thickness is generally diameter to wall material without any restriction. wall material can be glass, form oxide or interoxides, silicate, aluminosilicate, polymer, condensation polymer and the metal of pottery.

The saline flow conductivity (SFC) of the polymer of the formation hydrogel of swellable of the present invention is generally at least 20 * 10 ^-7Cm ³S/g, preferably at least 40 * 10 ^-7Cm ³S/g, more preferably at least 60 * 10 ^-7Cm ³S/g, even more preferably at least 150 * 10 ^-7Cm ³S/g, most preferably at least 300 * 10 ^-7Cm ³The SFC value of the polymer of the formation hydrogel that s/g. very particularly preferably obtains according to the present invention is 500-2000 * 10 ^- ^-7Cm ³S/g.

The particle mean size of preferred powder powder additive is more preferably less than 400 μ m. less than 2000 μ m

The particle mean size of powder additive preferably less than 50 μ m, is more preferably less than 10 μ m less than 200 μ m.

The present invention further provides the hygienic articles that comprises superabsorbents prepared in accordance with the present invention.

The polymer that can be used for especially crosslinked (being total to) the polymeric hydrophilic monomer of the polymer of formation hydrogel of swellable of the inventive method, poly-aspartate, grafting (be total to) polymer of one or more hydrophilic monomers on suitable graft bases, crosslinked cellulose ether, crosslinked starch ether or can be in aqueous fluids swollen natural prodcuts such as guar gum derivatives. treat that preferably crosslinked polymer is the polymer that comprises the construction unit that is derived from acrylic acid or its ester, perhaps by making acrylic acid or its ester polymer that graft copolymerization obtains on water-soluble polymer matrix. these hydrogels will be known to those skilled in the art and for example be described in US-4,286,082, DE-C-27 06 135, US-A-4,340,706, DE-C-37 13 601, DE-C-28 40 010, DE-A-43 44 548, DE-A-40 20 780, DE-A-40 15 085, DE-A-39 17 846, DE-A-38 07 289, DE-A-35 33 337, DE-A-35 03 458, DE-A-42 44 548, DE-A-42 19 607, DE-A-40 21 847, DE-A-38 31 261, DE-A-35 11 086, DE-A-31 18 172, DE-A-30 28 043, DE-A-44 18 881, EP-A-0 801 483, EP-A-0 455 985, EP-A-0 467 073, EP-A-0 312 952, EP-A-0 205 874, EP-A-0 499 774, DE-A-26 12 846, DE-A-40 20 780, EP-A-0 205 674, US 5,145,906, EP-A-0 530 438, EP-A-0 670 073, US 4,057,521, US 4,062,817, US 4,525,527, US 4,295,987, US 5,011,892, US 4,076,663 or US 4, in 931,497. as long as the content of above-mentioned patent documentation relates to the type and the preparation of these hydrogels is a part of this disclosure obviously just.

But the example of the hydrophilic monomer of the polymer of the formation hydrogel of suitable these swellables of preparation is the acid such as the acrylic acid of addition polymerization, methacrylic acid, vinyl sulfonic acid, vinyl phosphonate, maleic acid, maleic anhydride, fumaric acid, the itaconic acid, 2-acrylamido-2-methyl propane sulfonic acid, 2-acrylamido-2-methylpropane phosphonic acids and their amide, hydroxy alkyl ester and contain amino or the ester of amino-contained and amide and acid functional monomer's alkali metal salt and/or ammonium salt. can also use water miscible N-vinylamide such as N-vinyl formamide or diallyldimethylammonium chloride. preferred hydrophilic monomer is the chemical compound of general formula I:

Wherein

R ¹Be hydrogen, C ₁-C ₄Alkyl such as methyl or ethyl, perhaps carboxyl,

R ²For-COOR ⁴, hydroxyl sulfonyl or phosphono, use C ₁-C ₄The group of the phosphono of alkanol esterification or formula II:

R ³Be hydrogen, C ₁-C ₄Alkyl such as methyl or ethyl,

R ⁴Be hydrogen, C ₁-C ₄Aminoalkyl, C ₁-C ₄Hydroxyalkyl, alkali metal ion or ammonium ion and

R ⁵Be sulfonyl, phosphono or carboxyl or alkali metal salts or ammonium salt separately.

C ₁-C ₄The example of alkanol is methanol, ethanol, normal propyl alcohol, isopropyl alcohol or n-butyl alcohol.

Particularly preferred hydrophilic monomer is acrylic acid and methacrylic acid and their alkali metal salts or ammonium salt, for example sodium acrylate, potassium acrylate or ammonium acrylate.

Being applicable to can be for natural origin or synthetic source by the graft bases that makes the hydrophilic hydrogel that ethylenic unsaturated acid or their alkali metal salts or ammonium salt graft copolymerization obtains. and example is a starch, cellulose or cellulose derivative and other polysaccharide and oligosaccharide, polyoxyalkylene, especially polyoxyethylene and polyoxypropylene, and hydrophilic polyesters.

Suitable polyoxyalkylene for example is a formula III

Wherein

R ⁶, R ⁷Be hydrogen independently, C ₁-C ₁₂Alkyl such as methyl, ethyl, n-pro-pyl or isopropyl, C ₂-C ₁₂Alkenyl such as vinyl, positive acrylic or isopropenyl, C ₇-C ₂₀Aralkyl such as benzyl, 1-phenethyl or 2-phenethyl, perhaps aryl such as 2-aminomethyl phenyl, 4-aminomethyl phenyl or 4-ethylphenyl,

R ⁸For hydrogen or methyl and

N is the integer of 1-10000.

R ⁶And R ⁷Be preferably hydrogen, C separately ₁-C ₄Alkyl, C ₂-C ₆Alkenyl or phenyl.

Preferred hydrogel is polyacrylate, poly-methyl acrylate and US-4 especially, and 931,497, US-5,011,892 and US-5,041,496 graft polymers.

The preferred crosslinked polymer that has made the formation hydrogel of swellable, be that they comprise the chemical compound with at least two two keys that aggregates into polymeric network. suitable crosslinking agent is N especially, N '-methylene bisacrylamide and N, the two Methacrylamides of N '-methylene, the unsaturated monocarboxylic acid of polyhydric alcohol or the ester of polybasic carboxylic acid, for example diacrylate or triacrylate such as butanediol diacrylate, butanediol dimethylacrylate, glycol diacrylate or ethylene glycol dimethacrylate and trimethylolpropane triacrylate, and allyl compound is as (methyl) allyl acrylate, triallyl cyanurate, diallyl maleate, the polyene propyl diester, tetraene propoxyl group ethane, triallylamine, the tetraallyl ethylenediamine, phosphonic allyl ester and vinyl phosphonic acid derivative are for example described in EP-A-0343 427. and the inventive method can also be utilized and use polyallyl ether as cross-linking agent and by making the acid homopolymerization of acrylic acid prepare hydrogel. and suitable crosslinking agent is pentaerythritol triallyl ether, pentae-rythritol tetraallyl ether, the Polyethylene Glycol diallyl ether, the ethylene glycol bisthioglycolate allyl ether, the glycerol diallyl ether, glycerol triallyl ether, polyallyl ether and ethoxylated product thereof based on Sorbitol.

The method that preferred preparation can be used for the base polymer of the inventive method is described in " ModernSuperabsorbent Polymer Technology ", F.L.Buchholz and A.T.Graham, Wiley-VCH, 1998, in the 77-84 page or leaf. particularly preferably in the base polymer for preparing in the kneader, for example described in WO-A-01/38402, the base polymer that perhaps prepares in belt reactor is for example described in EP-A-0 955 086.

Water absorbent polymer is preferably polyacrylic acid or polyacrylate. and this water absorbent polymer can be by being prepared by the known method of document. preferably comprise 0.001-10mol%; the polymer of preferred 0.01-1mol% cross-linking comonomer; but the polymer that obtains by radical polymerization very particularly preferably; and wherein used the unsaturated free-radical crosslinking agent of polyfunctional olefinic (for example pentaerythritol triallyl ether or trimethylolpropane allyl ether) that has at least one free hydroxyl group in addition if. the polymer of the formation hydrogel of swellable is by known addition polymerization process preparation itself. the preferred addition polymerization that in aqueous solution, carries out with gel polymerisation. it comprises the aqueous solution and the suitable graft bases of one or more hydrophilic monomers that for example make 15-50 weight %; in the presence of radical initiator by utilizing Trommsdorff-Norrish (Trommsdorf-Norish) effect (Makromol.Chem.1; 169 (1947)) addition polymerization; preferably do not use mechanical mixture. sudden reaction can be at 0-150 ℃; under preferred 10-100 ℃ the temperature; also can under superatmospheric pressure or decompression, carry out at atmospheric pressure. usually; addition polymerization also can be under protective gas atmosphere; preferably under nitrogen, carrying out. addition polymerization can use high-energy electromagnetic rays or conventional chemical addition polymerization initiator to cause; these initiators are organic peroxide such as benzoyl peroxide for example; t-butyl hydroperoxide; methyl ethyl ketone peroxide; cumene hydroperoxide, azo-compound such as azodiisobutyronitrile and inorganic peroxide are as (NH ₄) ₂S ₂O ₈Or K ₂S ₂O ₈Or H ₂O ₂. if they can be suitable and Reducing agent such as sodium sulfite and ferrous sulfate (II), perhaps redox system is used in combination, wherein the reduction components that comprises of redox system is Mannich adduct, aldehyde and the amino-compound of aliphatic sulfinic acid and aromatic sulfinic acid such as benzenesulfinic acid and toluenesulfinic acid or these sour derivants such as sulfinic acid, for example described in the DE-A-13 01 566. the polymer properties feature can by with polymer gel at 50-130 ℃, post-heating a few hours under preferred 70-100 ℃ the temperature and further improving.

Based on used monomer, the gained gel for example can be neutralized to 0-100mol%, preferred 5-90mol%, especially 25-80mol%, very preferably 30-55mol% and 70-75mol%, can be used for neutral conventional nertralizer and be preferably alkali metal hydroxide or alkali metal oxide, but more preferably sodium hydroxide, sodium carbonate and sodium bicarbonate.

Neutralization is sneaked in the gel and is realized by will or being preferably solid nertralizer as aqueous solution usually. for this reason, for example by meat grinder with the gel mechanical activation comminution, and nertralizer sprayed, scatter or pour into thereon, carefully sneak into then. the gelatinous mass that obtains can be come homogenize by meat grinder repeatedly then. then with neutral gelatinous mass with belt dryer or pot type exsiccator drying, preferably be lower than 10 weight % until residual moisture content, especially being lower than 5 weight %. grinds exsiccant hydrogel and screening then, usually can use three-stage roll mill, needle mill or oscillating mill grind. and the granularity of the hydrogel of screening is preferably 45-1000 μ m, more preferably 45-850 μ m, even more preferably 100-800 μ m, also more preferably 100-700 μ m. in addition preferred size be 100-500 μ m, 300-600 μ m, less than 400 μ m, be more preferably less than 300 μ m, most preferably less than 150 μ m. at least 80%, all granules of preferred at least 90% are in this scope.

The back crosslinked of the polymer of the formation hydrogel of swellable undertaken by cross-linking agent solution behind the surface is sprayed on the dry-basis polymer powder usually.

After spraying, with the polymer powder heated drying, and not only also cross-linking reaction can take place in dry run before drying.

The spraying cross-linking agent solution is preferably at reaction mixer or mixing and drying baker, for example

Blender,

Blender,

Blender,

Blender, Exsiccator and

In carry out. also can use fluidized bed dryer.

Drying can be undertaken by heating jacket or introducing thermal air current in blender self. can use downflow type exsiccator such as pan dryer, Rotary pipe type baking oven and heatable screw rod equally. but also can for example use azeotropic distillation as drying means.

Preferred baking temperature is 50-250 ℃, preferred 60-200 ℃, and more preferably 70-180 ℃. preferably the time of staying under this temperature preferably less than 30 minutes, was more preferably less than 10 minutes less than 60 minutes in reaction mixer or exsiccator.

Back, surface cross-linking agent can use separately or be used in combination with following other back, surface cross-linking agent; Ethylene glycol diglycidyl ether for example; the diethylene glycol diglycidyl ether; polyethyleneglycol diglycidylether; propylene glycol diglycidylether; the dipropylene glycol diglycidyl ether; polypropylene glycol diglycidyl ether; glycerin diglycidyl ether; the polyglycereol diglycidyl ether; chloropropylene oxide; ethylenediamine; ethylene glycol; diethylene glycol; 2,2'-ethylenedioxybis(ethanol).; Polyethylene Glycol; propylene glycol; dipropylene glycol; tripropylene glycol; polypropylene glycol; butanediol; 1; ammediol; 1; the 4-butanediol; bisphenol-A; glycerol; trimethylolpropane; tetramethylolmethane; sorbitol; diethanolamine; triethanolamine; ethylenediamine; ethylene carbonate; propylene carbonate; 2-oxazolidone such as 2-oxazolidone or N-ethoxy-2-oxazolidone; 2; 3-morpholine diketone such as N-2-ethoxy-2; the 3-morpholine diketone; N-methyl-2; the 3-morpholine diketone; N-ethyl-2; the 3-morpholine diketone and/or the N-tert-butyl group-2; the 3-morpholine diketone; 2-oxo tetrahydrochysene-1; the 3-piperazine; N-acyl group-2-oxazolidone such as N-acetyl group-2-oxazolidone; bicyclic amide acetal such as 5-methyl isophthalic acid-azepine-4; 6-two oxa-dicyclo [3.3.0] octanes; 1-oxa--4; 6-two oxa-dicyclo [3.3.0] octanes and/or 5-isopropyl-1-azepine-4; 6-two oxa-dicyclo [3.3.0] octanes, and/or two-2-oxazolidone and poly-2-oxazolidone.

Preferably cross-linking agent behind the surface is dissolved in not can self-reacting solvent in, preferably be dissolved in lower alcohol for example methanol, ethanol, isopropyl alcohol, propylene glycol, ethylene glycol, in the preferred isopropyl alcohol, most preferably be dissolved in the aqueous solution of the suitable alcohol of this class, this moment, the pure content of solution was 10-90 weight %, more preferably 25-70 weight %, especially 30-50 weight %.

The consumption of back, surface cross-linking agent is 0.01-1 weight % based on used polymer, and the consumption of cross-linking agent solution itself is 1-20 weight % based on used polymer, preferred 3-15 weight %.

The AUL 0.7psi value [g/g] of the polymer of the formation hydrogel of swellable of the present invention can and be preferably greater than 10 by the measurement of institute's reported method in DE-A-199 09 653, especially greater than 15, more preferably greater than 20, especially greater than 25, especially is preferably greater than 30.

The polymer of the formation hydrogel of swellable of the present invention is used for absorbing blood and/or body fluid in hygienic articles such as incontinence articles, diaper, tampon, liner. and for this reason, usable fibers such as cellulose and fleece are handled the polymer of formation hydrogel of swellable of the present invention to form absorb composite material.

Be used for the dendritic of the inventive method because their nonlinear organization is hydrophilic, but their special geometric form have significantly reduced for crosslinked any undesirable tendency after the heat, make dendritic in surperficial post-processing operation process, to add. without any need for other blend step. for the viscosity in aqueous solution of the superabsorbents of initial stage or complete swelling, particularly advantageous at this is spherical. therefore, even under the high polymer consumption, still keep high saline flow conductivity.

The powder adhesive power excellence of dendritic, the ability of especially bonding powdery or Powdered additive. after the machinery of harshness exposes and after directly using, in fact not having in product can detected fine powder.

The influence of solvent for use when the transmission performance of end product also is subjected to the back, surface crosslinked. propylene glycol/water obviously is better than isopropanol. on the other hand, unconverted propylene glycol (being different from unconverted isopropyl alcohol) is difficult to remove and stay in the final products. when using propylene glycol, the pure content of exsiccant end product is generally the 5000-15000 ppm by weight, but when using preferred isopropyl alcohol, alcohol content is less than 1000 ppm by weight, preferably, be more preferably less than 100 ppm by weight less than 500 ppm by weight.

In the methods of the invention, the adding of dendritic make use in can be behind the surface crosslinked isopropanol (30 weight % isopropyl alcohols in water) as solvent only to obtain having so far the superabsorbents of the transmission performance that can just obtain by use propylene glycol/water (30 weight % propylene glycol in water).

For measuring the quality of post processing of the present invention, test exsiccant hydrogel by following method of testing described here:

Method:

Except as otherwise noted, measurement should be carried out under the relative humidity of 23 ± 2 ℃ ambient temperature and 50 ± 10%. the polymer of the formation hydrogel of swellable fully is mixed for measuring.

Centrifugal reserve capability (CRC)

This method has been measured the free swell of hydrogel in tea bag. 0.2000 ± 0.0050g dried hydrogel of weighing (particle fraction 106-850 μ m) and packing into then is of a size of in 60 * 85mm tea bag. tea bag was placed 30 minutes in 0.9 excessive weight % sodium chloride solution (0.83L sodium chloride solution/1g polymer powder at least). then under 250G, with centrifugal 3 minutes of tea bag. by the tea bag mensuration after centrifugal of weighing by the amount of liquid of hydrogel reservation.

Centrifugal reserve capability also can be measured by the centrifugal reserve capability method of testing No.441.2-02 that is recommended by EDANA (Europe is with promptly abandoning with non-weaving cloth association (European Disposables and Nonwovens Association)).

Absorbability under the load (AUL) 0.7psi (4830Pa)

The measuring cell that is used to measure AUL 0.7psi value is internal diameter 60mm, the Plexiglas cylinder of high 50mm. sticking to below it is at the bottom of mesh size is the stainless steel sift of 36 μ m. measuring cell comprises that also diameter is the vinyl disc of 59mm and counterweight that can be in vinyl disc places measuring cell. the altogether heavy 1344g. of measuring cell and counterweight by measuring empty Plexiglas cylinder the weight and the weight of vinyl disc and it is recorded as W ₀And measure AUL 0.7psi. weigh then 0.900 ± 0.005g swellable the formation hydrogel polymer (particle size distribution 150-800 μ m) and put into the Plexiglas cylinder and be evenly dispersed in very much at the bottom of the stainless steel sift on. then vinyl disc is put into carefully the Plexiglas cylinder, whole unit is weighed and is W weight record _a. counterweight is put on the vinyl disc of Plexiglas cylinder then. be 120mm with diameter then, high for 10mm and porosity be that to place diameter be 200mm for 0 ceramic filtering plate (from the Duran of Schott), height is the centre of the petri diss of 30mm, and introduce 0.9 enough weight % sodium chloride solution, liquid level is mutually neat with the filter plate surface, and the filter plate surface of not getting wet. be 90mm with diameter then, the aperture less than the round filter paper of 20 μ m (from Schleicher; The S ﹠amp of Sch ü ll; S 589 Schwarzband) place on the ceramic wafer. will be equipped with then the Plexiglas cylinder of polymer of formation hydrogel of swellable and vinyl disc and counterweight be placed on filter paper above, and placed 60 minutes. after this process finishes, the filter paper of whole unit from petri diss is taken out, from the Plexiglas cylinder, taking out counterweight then. the Plexiglas cylinder that swollen hydrogel will be housed is weighed with vinyl disc and counterweight, and is W with weight record _b.

Absorbability under the following computational load (AUL):

AUL?0.7psi[g/g]＝[W _b-W _a]/[W _a-W ₀]

Absorbability under the load also can be measured by the method for testing No.442.2-02 that absorbs under pressure that is recommended by EDANA (Europe is with promptly abandoning and non-weaving cloth association).

Saline flow conductivity (SFC)

Described in EP-A-0 640 330, measure the saline flow conductivity of swell gel layer under the confined pressure of 0.3psi (2070Pa), gel layer permeability as the swell gel layer of super absorbent polymer, although it mainly is not re-use glass dust (40) that the device described in the 19th page of the patent application that will before quote and Fig. 8 changes into, piston (39) is made by the plastic material identical with cylinder (37) and is contained 21 holes that are evenly distributed on the same size on the whole contact surface now. and compare with EP-A-0 640 330, the evaluation of program and measurement remains unchanged. write down flow velocity automatically.

Following calculating saline flow conductivity (SFC):

SFC[cm ³s/g]＝(F _g(t＝0)×L ₀)/(d×A×WP)，

F wherein _g(t=0) be F from flow-speed measurement _g(t) data are by the flow velocity (g/s) of the NaCl solution that is extrapolated to the t=0 linear regression analysis and obtains; L ₀Be gel thicknesses (cm); D is the density (g/cm of NaCl solution ³); A is the area (cm of gel layer ²); WP is the hydrostatic pressure (dyn/cm on the gel layer ²).

Flow velocity (FLR)

The polymer that this method has been measured the formation hydrogel of swellable flows through the speed of funnel (funnel). the 100 ± 0.01g dried hydrogel and put into sealable metal funnel of weighing. and with the weight record of the polymer of the formation hydrogel of swellable is W ₁. funnel is 145.0 ± 0.5mm corresponding to the height of deutsche industrie norm DIN 53492. funnel effusers, and internal diameter is 10.00 ± 0.01mm. hopper walls with respect to the inclination angle of level is 20 °. with metal funnel ground connection. subsequently funnel is opened and the bucket that leaks hunting becomes the empty required time. and will the time be designated as t.

Carry out twice measurement. the difference of twice measured value of gained must be no more than 5%.

Following calculating flow velocity (FLR):

FLR[g/s]＝W ₁/t

Flow velocity also can be measured by the flow rate test method No.450.2-02 that EDANA (Europe is with promptly abandoning and non-weaving cloth association) recommends.

Pour out (pour-out) weight (ASG)

This method has been measured the density of polymer after pouring out of the formation hydrogel of swellable. measures according to the cylindrical density bottle of DIN 53466 usefulness. and the volume of density bottle (V) is 100.0 ± 0.5ml, internal diameter is 45.0 ± 0.1mm, highly is the bare weight that 63.1 ± 0.1mm. claims density bottle. weight is designated as W ₁. the about 100g dried hydrogel and put into sealable metal funnel of weighing. with this weight record is W ₁. funnel is 145.0 ± 0.5mm corresponding to the height of deutsche industrie norm DIN 53492. funnel effusers, internal diameter is 10.00 ± 0.01mm. hopper walls with respect to the inclination angle of level is 20 °. with metal funnel and density bottle ground connection. subsequently funnel is emptied into density bottle, the polymer of the formation hydrogel of excessive swellable overflows. and the polymer of the formation hydrogel of the swellable that will overflow with scraper strikes off. the density bottle that weighing is filled, and be W with weight record ₂.

Weight (ASG) is poured out in following calculating:

ASG[g/ml]＝[W ₂-W ₁]/V

Pouring out weight also can be measured by the density measurement method No.460.2-02 that EDANA (Europe is with promptly abandoning and non-weaving cloth association) recommends.

The fragility test

The polymer that fragility test is used for measuring the formation hydrogel of swellable is exposed to the behavior under the mechanical stress.To test with sealable porcelain cup. the diameter of porcelain cup is 85.7mm (33/8 inch), and height is 111.1mm (43/8 inch), and volume is 379cm ³(0.1 gallon). the diameter of opening is 31.8mm (11/4 inch). height with cover is 139.7mm (51/2 inch). the cylindrical porcelain mill medium of the polymer of the formation hydrogel of the 50g swellable of in porcelain cup, packing into and 127g. the diameter of porcelain mill medium is 12.7mm (1/2 inch), it highly is 12.7mm (1/2 inch), each weight is about 5.3g. filling porcelain cup and goes up 180rpm rotation 15 minutes in three-stage roll mill (for example from U.S.Stoneware, the U.S.).

Powder

The powder fraction can be measured by the powder method of testing No.490.2-02 that EDANA (Europe is with promptly abandoning and non-weaving cloth association) recommends.

The agglomeration resistance test

In the glass beaker of 100ml, be weighed into the polymer of the formation hydrogel of 30g swellable. subsequently beaker was deposited 2 hours under 40 ℃ and 95% relative humidity. after depositing, pour out the polymer of the formation hydrogel of swellable. pour out behavior with following grade qualitative evaluation, wherein " non-constant " is meant that the polymer that has formed the formation hydrogel of stable skin and swellable on the polymer surfaces of the formation hydrogel of swellable stays in the beaker, " very good " be meant and the intact gold of the polymer of the formation hydrogel of swellable can be poured out, and is positioned at the polymer that intermediary value is meant the formation hydrogel of a circle swellable and stays on the walls of beaker.

Embodiment

Embodiment 1 and 2:

SAP 500Z base polymer is existed

Pass through in the laboratory blender with 3.16 weight % isopropanol (30: 70) and the spraying of 0.085 weight %2-oxazolidone (the percentage number average is based on base polymer), and be heated to subsequently 175 ℃ following 120 minutes and to carry out the back crosslinked. in operation suitable words add dendritic. with resulting polymers screening and remove piece under 850 μ m subsequently. by the fine powder (＜10 μ m) of test of laser discharge pipe method and assay products. same product is carried out the machinery decomposition by three-stage roll mill, and powder is tested again.

Claims

1. the polymer of the formation hydrogel of swellable comprises the hydrophilic polymer of at least a dendritic structure of 10 weight % at the most based on the polymer of the formation hydrogel of this swellable.

2. according to the polymer of claim 1, the polymer of the formation hydrogel of wherein said swellable comprises the hydrophilic polymer of the dendritic structure of at least 0.005 weight %.

3. according to the polymer of claim 1, the hydrophilic polymer of wherein said dendritic structure is by polyhydric alcohol and 2, the polyester that the 2-dihydromethyl propionic acid forms.

4. according to the polymer of claim 2, the hydrophilic polymer of wherein said dendritic structure is by polyhydric alcohol and 2, the polyester that the 2-dihydromethyl propionic acid forms.

5. according to the polymer of claim 1, the hydrophilic polymer of wherein said dendritic structure is polypropylen imine, polyamide-amide or polyesteramide.

6. according to the polymer of claim 2, the hydrophilic polymer of wherein said dendritic structure is polypropylen imine, polyamide-amide or polyesteramide.

7. according to each polymer among the claim 1-6, it also comprises Powdered and/or powder additive.

8. according to the polymer of claim 7, wherein said additive is slaine, pyrolysismethod silicon oxide, polysaccharide, non-ionic surface active agent, wax and/or kieselguhr.

9. according to the polymer of claim 7, wherein said additive is that 1-1000 μ m and its wall thickness are that the form of the tiny balloon of the described diameter of 1-10% exists with the diameter.

10. polymer according to Claim 8, wherein said additive are that 1-1000 μ m and its wall thickness are that the form of the tiny balloon of the described diameter of 1-10% exists with the diameter.

11. according to each polymer among the claim 1-6, it comprises less than the diameter of the 50 ppm by weight granule less than 10 μ m.

12. according to the polymer of claim 7, it comprises less than the diameter of the 50 ppm by weight granule less than 10 μ m.

13. each polymer according to Claim 8-10, it comprises less than the diameter of the 50 ppm by weight granule less than 10 μ m.

14. according to each polymer among the claim 1-6, it comprises after being exposed to mechanical stress less than the diameter of the 50 ppm by weight granule less than 10 μ m.

15. according to the polymer of claim 13, it comprises after being exposed to mechanical stress less than the diameter of the 50 ppm by weight granule less than 10 μ m.

16. a method for preparing according to the polymer of the formation hydrogel of each swellable among the claim 1-15, it comprises exsiccant water absorption hydrogel is mixed with the hydrophilic polymer of at least a dendritic structure.

17. according to the method for claim 16, the hydrophilic polymer of wherein said dendritic structure is by polyhydric alcohol and 2, the polyester that the 2-dihydromethyl propionic acid forms.

18. according to the method for claim 16, the hydrophilic polymer of wherein said dendritic structure is polypropylen imine, polyamide-amide or polyesteramide.

19., wherein described post processing crosslinked operation behind the surface is carried out according to each method among the claim 16-18.

20. according to the method for claim 19, the solvent that wherein comprises back, at least a surface cross-linking agent is the mixture of isopropyl alcohol and water.

21. according to each the purposes of polymer in absorbing blood and/or body fluid among the claim 1-15.

22., be used for absorbing urine according to the purposes of claim 21.

23. comprise hygienic articles according to each polymer among the claim 1-15.