CN1129911A - Aqueous fluid absorbent polymers having a superior balance of absorptive properties - Google Patents

Abstract

The subject invention pertains to an aqueous fluid absorbent polymer having a superior balance of absorptive properties. In particular, the subject invention provides an aqueous fluid absorbent polymer characterized by a centrifuge capacity of at least 25 grams/gram, and an absorption under a 1.0 psi (70,000 dynes/cm<2>) load of at least 15 grams/gram. The subject invention further provides a process for preparing such polymers, which process employs an inhibitor during heat-treatment of the polymer. The subject invention further provides an absorbent structure comprising a fiber matrix and an aqueous fluid absorbent polymer characterized by a centrifuge capacity of at least 25 grams/gram, and an absorption under a 1.0 psi (70,000 dynes/cm<2>) load of at least 15 grams/gram.

Description

Balanced water liquid absorbable polymer with excellent absorption performance

Theme of the present invention is relevant with a kind of water liquid absorbable polymer with improved performance, and is relevant with the method for this polymer of preparation, relevant with the absorbent structure in conjunction with this polymer.

Water liquid absorbable polymer (also claiming super absorbent polymer) is used in the private health product such as the such absorb body fluids of baby diaper, adult's incontinence article and women sanitary articles at first, in these are used, water liquid absorbable polymer is attached in the absorbent structure, these absorbent structures often contain synthetic and/or natural fiber base or paper substrate weaving and non-woven constructions, or such as the so tough and tensile corpus fibrosum of fluffy gauze piece.When anhydrous liquid absorbable polymer, the absorptive capacity of these structures is very limited, and owing to need lot of materials that enough absorptive capacities are provided, causes the volume of absorbent structure very huge, and can not retain liquid well under pressure.If the water liquid absorbable polymer that forms the expanded balloon material after the imbibition is mixed absorbent structure, be suitable for improving the absorptive capacity and the absorption under pressure of absorbent structure, and by reducing the consumption of (if not getting rid of) required puff or fiber, dwindled volume, even and can make absorbent structure under dampness, a kind of " exsiccant sensation " also arranged.

The performance of water liquid absorbable polymer is usually by considering that various character weigh.Such as the polymer volume, polymer absorbs the ability of water liquid, the content of the residual monomer that exists in the content of uncrosslinked the extracted polymer that exists in the polymer and the polymer under different pressures.Ideally, industrial more preference has high power capacity and the high polymer that absorbs, and less application of pressing in taking into account.Industrial usually preferred this have the extracted polymer of low content and the polymer of low levels of residual monomer feature.Yet reach the balance of this performance, proved very difficult.

When the degree of cross linking reduces, promptly obtain looser polymer network ability raising capacity.When but the degree of cross linking reduced, the ability that absorbs water liquid under pressure had also reduced, and the content of uncrosslinked extracted polymer has improved.Though obtaining to have high power capacity and under relatively low pressure, for example pressure is 21000 dynes per centimeter ²(0.3psi), have the high polymer aspect that absorbs and obtained progress, but have high power capacity and (for example pressure is 70000 dynes per centimeter under elevated pressures ²(1.0psi)) have the high polymer that absorbs but is not resolved always.

PCT patent application 92/07611 discloses a kind of preparation method of water liquid absorbable polymer of the absorbent properties with improvement, wherein, and in order to improve 21000 dynes per centimeter ²(0.3psi) AUL, and centrifugal capacity is not had the influence of significant adverse under the situation that does not have surface crosslinking agent, is being higher than heat treatment under 165 ℃ the temperature with exsiccant water liquid absorbable polymer.In a preferred specific embodiments, PCT patent application 92/07611 discloses with preferred cross-linking agents (methylene-bisacrylamide for example, two (acrylamido) acetic acid and salt thereof, allyl acrylate, allyl methacrylate and other difunctionality mono-vinyl and monoene propyl ester and amide) after crosslinked water liquid absorbable polymer heat-treats, just can obtain having the centrifugal capacity that improved and the polymer of the absorbability (AUL) under the load.

UK Patent Application 9208449.0 discloses the water liquid absorbable polymer that contains carboxy moiety, and this polymer uses C _2-10The polyhydroxy hydrocarbon is crosslinked, and 2-8 the ethylene oxide unit ethoxylations of the ethylene oxide chain of each hydroxylic moiety of this hydrocarbon.Wherein, every terminated hydroxylic moiety C _2-10Unsaturated carboxylic acid or its ester esterification, one of them example are the trimethylolpropane triacrylates of height ethoxylation.In a preferred specific embodiments, water liquid absorbable polymer is heat-treated behind dry and screening granule.Use the cross-linking agent of this ethoxylation, especially when preparing, can access water liquid absorbable polymer: the medium centrifugal capacity of 25-35g/g scope, 21000 dynes per centimeter with following characteristic by the polymer Technology for Heating Processing ²(0.3psi) the AUL scope is 25-31g/g and 70000 dynes per centimeter ²(1.0psi) the AUL scope is 7-18g/g.Have been found that in these scopes the product with the high centrifugal capacity centrifugal capacity of range limit (for example) has 70000 dynes per centimeter of scope lower limit ²(1.0psi) AUL, and have 70000 high dynes per centimeter ²(1.0psi) AUL (70000 dynes per centimeter for example ²(1.0psi) AUL is between 10-18g/g) product have the centrifugal capacity of scope lower limit.Also not occurring the centrifugal capacity of existing height till now has the water liquid absorbable polymer of high AUL again.

Just can not reach all very high degree of absorption under capacity and the relative high pressure with the heat treatment of the crosslinked water liquid absorbent material of preferred cross-linking agents (as PCT patent application 92/07611 and UK Patent Application 9208449.0 disclosed cross-linking agent) itself, for example existing centrifugal capacity greater than 25g/g has 70000 dynes per centimeter greater than 15g/g again ²(1.0psi) AUL.Though do not wish to be fettered in theory, but think at present during heating treatment, in all other reactions, the lytic response of chain has taken place, it is generally acknowledged that this reaction has caused the reduction of crosslink density, and the crosslink density of particle surface is when reducing, and the height under relatively high pressure absorbs potentiality and descends equally.

US4666983 discloses a kind of absorbing products, and it mixes to come crosslinked by the absorbent resin powder with 100 parts of heave hand carboxyls with the cross-linking agent of 0.0001-10 parts of weights be to be present near the strand of absorbent resin powder surface to obtain at least.US4734478 discloses a kind of water-absorbent resin powder with crosslinked strand near surface.This toner mixes with 0.001-10 parts heavy polyhydric alcohol by heavily containing the carboxyl water-absorbent resin powder with 100 parts, and heating blends under at least 100 ℃ of temperature makes powder and polyol reaction and obtains.This kind improvement is included in the powder of per 100 parts of weights, has under the existence of water of 0.01-8 parts heavy hydrophilic organic solvent and 0-8 parts of weights, and powder is mixed with polyhydric alcohol.This surface crosslinking agent works by issuing biochemical reaction on its surface in the temperature that improves with polymer, further at surface crosslinked polymer.But this surface crosslinking agent can not stop the chain cracking under the high temperature.Therefore, though the use of surface crosslinking agent can manage to remedy the consequence of chain interruption, can not reduce or stop its generation.

Industry will find to show the huge advantage of the water liquid absorbable polymer that more high power capacity and the height under appropriate high pressure absorb; The height that industry also can be found not only to demonstrate under high power capacity and the appropriate high pressure absorbs, but also demonstrates the huge advantage of the extracted polymer and/or the monomeric water liquid of the low levels of residual absorbable polymer of low content; Industry also can find to prepare the very big convenient part of method of this polymer and the very big advantage of having mixed the absorbent structure of this type of water liquid absorbable polymer.With regard to above-mentioned definite character, this technology has the motility of best polymer performance.

Therefore, the invention provides a kind of water liquid absorbable polymer, but it comprises that ethylenically unsaturated monomer and the comonomer with the ethylenically unsaturated monomer copolymerization that uses in case of necessity are polymerized.This water liquid absorbable polymer is crosslinked by the cross-linking agent that contains two active parts at least, and this two part can be reacted with ethylenically unsaturated monomer and the comonomer that uses in case of necessity.Wherein, water liquid absorbable polymer is characterised in that: the centrifugal capacity of 25g/g and in 70000 dynes per centimeter at least ²(1.0psi) loading at least, 15g/g absorbs.The centrifugal capacity of polymer is preferably 28g/g, 30g/g, even 33g/g.35g/g or higher more preferably.1.0psi load down, the absorption of polymer is preferably 18,20, even 21g/g, 23g/g more preferably, 24g/g or higher.

The present invention also provides a kind of water liquid absorbable polymer, wherein, can extract polymer content and be lower than 18%, is preferably to be lower than 15%, more preferably is lower than 12%, can observe can extract polymer content and be lower than 10%.

Theme of the present invention also provides the method for preparing water liquid absorbable polymer, it comprises: a) in the presence of the cross-linking agent of two active parts that have the comonomer reaction of can be with ethylenically unsaturated monomer and using in case of necessity at least with ethylenically unsaturated monomer and use in case of necessity can with the comonomer polymerization of ethylenically unsaturated monomer copolymerization, formation water liquid absorbability pearl or hydrogel; B) except that solvent in the liquid absorbability pearl of anhydrating or the water in the hydrogel, form dry water liquid absorbent polymeric material; And c) this dry water liquid absorbent polymeric material of heat treatment under 170-240 ℃ temperature forms heat treated water liquid absorbent polymeric material; Wherein, this dry water liquid absorbent polymeric material contains inhibitor during the heat treatment of step (c), and this inhibitor provides after the polymerization of step (a) and before the heat treatment of step (c).

The present invention also provides a kind of absorbent structure that comprises fibre substrate and water liquid absorbent material, it is characterized in that: the centrifugal capacity of 25g/g and in 70000 dynes per centimeter at least ²(1.0psi) the load absorption of 16g/g at least down.

Describe in detail

As U.S. Patent application series 756731, UK Patent Application 9208449.0 and PCT patent application 92/07611 are described, and the dry after-baking of water liquid absorbable polymer has improved the balance of absorbent properties, for example in 21000 dynes per centimeter ²(0.3psi) absorption under the load and the balance between the centrifugal capacity.Although but do not wish to fetter in theory to some extent, it is generally acknowledged that heat treatment has promoted the free radical competitive reaction, because the influence of oxygen, this reaction can cause the chain cracking, causes crosslink density to reduce.Through practice of the present invention, before heat treatment, a kind of inhibitor is added in the dry polymer, and usually is aqueous solution or water/organic solution.It is generally acknowledged that inhibitor is by catching the radical reaction that the free radical that is formed by heat treatment reduces or suppresses not expect before the chain cracking takes place.Regardless of related reaction mechanism, polymer of the present invention has the harmony of superior absorbent properties.

Water liquid absorbable polymer of the present invention is obtained by one or more ethylenically unsaturated monomers, for example, and ethylenically unsaturated carboxylic acids, ethylenically unsaturated carboxylic acids acid anhydride or its salt.Preferred ethylenically unsaturated carboxylic acids and carboxylic acid anhydrides monomer comprise with acrylic acid, methacrylic acid, ethylacrylic acid, α-chloroacrylic acid, α-alpha-cyanoacrylate, β-methacrylic acid (.beta.-methylacrylic acid), iso-crotonic acid, α-phenylacrylic acid is the acrylic acid, β-acryloxy propionic, sorbic acid, α-chloro sorbic acid, angelic acid, cinnamic acid of representative, to chloro-cinnamic acid, β-styrene acrylic (1-carboxyl-4-phenyl butadiene-1,3), itaconic acid, citraconic acid, mesaconic acid, glutaconate, maleic acid, fumaric acid and maleic anhydride.Preferred ethylenically unsaturated monomer is an acrylic acid, methacrylic acid or its salt.Most preferably acrylic acid or its salt.

In addition, water liquid absorbable polymer can comprise that one or more well known in the artly are used for water liquid absorbable polymer or grafted comonomer or other comonomer on ethylenically unsaturated monomer, as acrylamide, Methacrylamide, 2-acrylamido-2-methyl-1-propane sulfonic acid, acrylonitrile, vinyl pyrrolidone, vinyl sulfonic acid, cellulose family monomer, modified cellulose class monomer, polyvinyl alcohol, glucidtemns and its salt.When the graft polymers that uses as polyvinyl alcohol, usually approximately to 30% of ethylenically unsaturated monomer weight, more Chang Zhiyue 10% for consumption.

Preferred water liquid absorbable polymer is the hydrolysate of starch-acrylonitrile graft copolymer, the part neutralized reaction product of Starch and Acrylic Acid graft copolymer, the saponification resultant of vinyl acetate-acrylate copolymer, the hydrolysate of acrylonitrile copolymer, the cross-linking products of the hydrolysate of acrylonitrile copolymer, the hydrolysate of acrylamide copolymer, the cross-linking products of the hydrolysate of acrylamide copolymer, the neutral polyacrylic cross-linking products of polyacrylic part neutralized reaction product and part.

Water liquid absorbable polymer preferably photocrosslinking makes it water insoluble.The cross-linked structure of expectation can be by selecting ethylenically unsaturated monomer and use in case of necessity comonomer and molecular cell in have two polymerizable double bonds at least the cross-linking agent copolymerization obtain, cross-linking agent exists with the effective amount of crosslinked this water-soluble polymer.The preferable amount of cross-linking agent is by the degree of the absorptive capacity of expectation and the intensity of keeping absorption liquid here of expectation, and promptly Qi Wang load absorbs (AUL) decision down.Usually be the cross-linking agent that per 100 parts of heavy ethylenically unsaturated monomers have 0.0005-1.5 parts of weights, preferred amount ranges is the cross-linking agent that per 100 parts of heavy ethylenically unsaturated monomers contain 0.1-1.5 parts of weights.If the cross-linking agent that uses in per 100 parts of ethylenically unsaturated monomers surpasses about 5 parts, the crosslinked polymer density that obtains is too high, and absorptive capacity will reduce, but the intensity of reservation absorption liquid can increase.If dosage of crosslinking agent is less than 0.0005 weight portion in per 100 parts, crosslinked polymer density is too low, and when becoming sticky when treating that absorption liquid contacts, initial absorption rate is also very low.

Though cross-linking agent often is dissolved in the monomer solution, it can be can be scattered in this solution and do not have bad influence.The use of this dispersant is existing open in US4833222.Suitable dispersant comprises the carboxymethyl cellulose suspension aids, methylcellulose, hydroxypropyl cellulose and polyvinyl alcohol.This type of dispersant concentration often is 0.005-0.1% (weight) of ethylenically unsaturated monomer gross weight.

Typical cross-linking agent comprises: the chemical compound that has two polymerizable double bonds at least; The chemical compound that has the functional group of the functional group reactions in the monomeric unit in the functional group of a polymerizable double bond and at least one and monomer reaction and and monomer or the polymer at least; Have two chemical compounds with the functional group of ethylenically unsaturated monomer reaction at least.Preferred cross-linking agents is included in the molecule has 2-4 such as CH ₂=CHCO-, CH ₂=C (CH ₃) CO-or CH ₂=CH-CH ₂The chemical compound of-group.In addition, preferred cross-linking agents comprises the polyvalent metal compounds that can form ionic cross-linked bond.

Have at least the typical compound of two polymerizable double bonds to have: divinyl or many vinyl compounds (as divinylbenzene, divinyl toluene, biethenyl-xylene, divinyl ether, dicthenone and triethylene benzene); Also have the diester of unsaturated monocarboxylic or polycarboxylic acid and polyhydric alcohol or polyester (as the dimethacrylate or the trimethyl acrylic ester of polyhydric alcohol, resemble ethylene glycol, diethylene glycol, 2,2'-ethylenedioxybis(ethanol)., tetraethylene glycol (TEG), propylene glycol, dipropylene glycol, tripropylene glycol, four propylene glycol, trimethylolpropane, glycerol, polyoxyethylene glycol, polyoxy propylene glycol); Can be by above-mentioned any polyhydric alcohol and the unsaturated polyester (UP) that obtains such as the reaction of the such unsaturated acids of maleic acid; With can be by polyepoxide and metering system acid reaction and the dimethacrylate or the trimethyl acrylic ester that obtain; Such as N, two Methacrylamides that N-methylene-bisacrylamide is such; Can be by polyisocyanate (as benzal vulcabond, hexamethylene diisocyanate, 4,4 '-methyl diphenylene diisocyanate and can contain the NCO prepolymer by what this kind isocyanate and the chemical compound reaction that contains reactive hydrogen atom obtained) with the carbamyl ester that the hydroxyl monomer reaction obtains, for example react available dimethacrylate carbamyl ester with above-mentioned vulcabond and hydroxyethyl meth acrylate; Such as aklylene glycol, the polyhydric alcohol that glycerol, poly alkylene glycol, polyoxy sub alkyl polylol are such and the dimethyl-allyl or the poly-methallyl ether of saccharide, Polyethylene Glycol diallyl ether for example, allylation starch and allylation cellulose, the diallyl ester of polybasic carboxylic acid or polyene propyl ester, for example diallyl phthalate and diallyl adipate; The ester of the monomethyl allyl ester of unsaturated monocarboxylic or polycarboxylic acid and polyhydric alcohol, for example methacrylate of Polyethylene Glycol monoallyl ether.

Preferably have at least a polymerizable double bond and at least one to comprise with the chemical compound of the functional group of monomer reaction: contain at least one can with carboxyl, carboxylic acid anhydrides, hydroxyl, the alefinically unsaturated compounds of the group of amino or amide groups reaction, this compounds comprises N-methylol methacrylamide and glycidyl methacrylate.

Preferably have at least two can comprise with the chemical compound of the functional group of monomer reaction: contain can with two functional groups or the polyfunctional compound of the group of carboxyl, carboxylic acid anhydrides, hydroxyl, amino or amide groups reaction.Example has: Biformyl, such as phthalic acid and the such polyprotic acid of adipic acid; The polyhydric alcohol of above describing; Alkylenediamine (for example ethylenediamine) and the such polyamines of polyalkylenepolyamines.

The polyvalent metal compounds that preferably can form ionomer comprises oxide, hydroxide and salt of weak acid, for example carbonate of alkaline-earth metal and acetate.

Mention as PCT patent application 92/07611, a certain class cross-linking agent can produce particularly preferred absorbent properties.This class preferred cross-linking agents comprises: di-2-ethylhexylphosphine oxide acrylimide, two (acrylamide) acetic acid and its salt, allyl acrylate, allyl methacrylate and ester or amide with vinyl and allyl functionality.

As described in UK Patent Application 9208449.0, other preferred cross-linking agents comprises: the C that the ethylene oxide chain ethoxylation of 2-8 ethylene oxide units is arranged with each hydroxylic moiety _2-10Polyhydroxy hydrocarbon, wherein the hydroxylic moiety C of each chain end _2-10Unsaturated carboxylic acid or its ester esterification, one of example is a trimethylolpropane, used 2-7 ethylene oxide units of each hydroxylic moiety with its ethoxylation and wherein each hydroxyl used an acrylate-based esterification.This preferred cross-linking agents is called the trimethylolpropane triacrylate of height ethoxylation.

Especially preferred cross-linking agent has: ethylene glycol, diethylene glycol, 2,2'-ethylenedioxybis(ethanol)., propylene glycol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, neopentyl glycol, the diacrylate of trimethylolpropane and tetramethylolmethane and dimethylacrylate; The trimethylolpropene triacrylate and the trimethyl acrylic ester of height ethoxylation; Three (methyl) acrylic acid pentaerythritol ester of height ethoxylation, the tetraacrylate and the tetramethyl acrylate of tetramethylolmethane; Tetramethylolmethane four (methyl) acrylate of height ethoxylation; The tetraacrylate of tetramethylolmethane and tetramethyl acrylate; Tetraene propoxyl group ethane; Methylene-bisacrylamide; Two (acrylamide) acetic acid and its salt; Allyl acrylate; Allyl methacrylate; Ester or amide with vinyl and allyl functionality.A preferred class cross-linking agent is an allyl methacrylate, the trimethylolpropane triacrylate of the diallyl of polybasic carboxylic acid or polyenoid propyl ester and height ethoxylation.

In gel polymerisation technology, ethylenically unsaturated monomer, comonomer of Shi Yonging and cross-linking agent preferably are dissolved in case of necessity, be scattered in or be suspended in the water quality, its content range is 10-80% (weight) of monomer solution gross weight, is preferably 20-60%, to form reactant mixture.

In this aqueous reaction mixture, also can add other composition.For example when using the metal reaction container, perhaps the trace meter of removing in the solution with chelating agen is favourable.It is VERSENEXTMV-80 (the five sodium-salt aqueous solution of diethylene-triamine pentaacetic acid, the trade mark of Dow Chemical) that a kind of chelating agen is arranged, and this amount of chelant is generally 100-2000ppm based on ethylenically unsaturated monomer weight meter.

Conventional vinyl polyaddition reaction initiator can add reactant mixture easily.The radical polymerization initiator that fully is dissolved in the reactant mixture initiated polymerization is preferred.For example water-soluble peroxide is better.The example of water-soluble peroxide has such as Ammonium persulfate., potassium peroxydisulfate, sodium peroxydisulfate, water solublity persulfate, hydrogen peroxide, peroxidating decoyl that other alkali metal persulphate is such, benzoyl peroxide, cumene hydroperoxide, TBPB tertiary butyl perbenzoate, peracetic acid sodium, SODIUM PERCARBONATE hydroperoxides and water-soluble azo compounds, as 2,2 '-azo two (2-amidine propane HCl).Also can use conventional redox initiator system, this system is by combining formation with above-mentioned peroxide with Reducing agent such as sodium sulfite, sodium thiosulfate, ascorbic acid or its salt or ferrous salt.Initiator content is based on the ethylenically unsaturated monomer that exists and about at the most 5% (mole) of comonomer total mole number meter of use in case of necessity.Based on the ethylenically unsaturated monomer that exists in the reactant mixture and the comonomer total mole number meter that uses in case of necessity more preferably this initiator content be 0.001-0.5% (mole).

Can expect that the monomer at least about 95% can be transformed into polymer.Unneutralized or the neutral or neutral acid monomers of part carries out polymerization before the available polymerization.By being contacted with the alkaline matter of a certain amount of acidic group of 20-95% that is enough to exist in the neutralizing acid monomer, water-containing monomer finishes neutralization.During the consumption of alkaline matter preferably can be enough to and the acidic group in 40-85% acid monomers, in and 55-75% better.When the preneutralization monomer solution, the control neutrality condition is very important, so that the unlikely monomer mixture premature polymerization that causes of the heat of neutralization, about below 40 ℃, it is more favourable preferably to carry out neutralization ratio below 35 ℃.

To in and the useful chemical compound of monomer acids base those chemical compounds that have no adverse effect with acidic group and to polymerization technique in can be fully typically.These chemical compounds comprise alkali metal hydroxide, alkali carbonate and bicarbonate.The monomeric material that is used to neutralize is preferably sodium hydroxide or potassium hydroxide or sodium carbonate or potassium carbonate.When the degree of neutralization of decision expectation, must be careful, to guarantee the causing PH that obtains crosslinked absorbable polymer (this polymer will contact or be scattered in the water liquid that will absorb) to remain in the scope that is suitable for polymer applications.As well known in the art, also optional unneutralized monomer comes polymerization, later on neutralization again.

In the specific embodiments of a preferred preparation, prepared the neutral ethylenically unsaturated monomer of part, the comonomer of Shi Yonging in case of necessity, the aqueous solution of cross-linking agent and initiator to the polymer implementing the present invention and be suitable for.Polymerization of mixtures can be caused by the temperature that raising contains the mixture of initiator, and also the redox initiator of available foregoing description causes.For from monomer mixture, getting rid of and isolating oxygen, polyreaction can be caused suitably, react under the inert atmosphere of being everlasting and carry out (as under nitrogen or argon atmospher).

In general, the temperature range that polyreaction begins is 20-45 ℃, and the accurate temperature that carries out polyreaction will be according to monomeric type and concentration, and the type and size of initiator type and concentration and polymer reactor are selected.The maximum temperature range of polyreaction is preferably 50-100 ℃, more preferably 60-90 ℃, most preferably is 70-85 ℃.Because exothermic heat of reaction can expect to provide a kind of method of cooling reactor to keep temperature desired.The method of control polymeric reaction temperature is not really strict, fills the cooling of sending out and gets rid of the heat that produces between polymerization period as long as have.

Reactant mixture will react a period of time, makes monomer be enough to change into as required cross-linked hydrogel.Preferred conversion ratio is 95% or higher, more preferably 98% or higher, most preferably be 99% or higher.In order to reach this conversion ratio, the response time usually is 20 minutes at least, and more frequent is at least 40 minutes, the most often is at least one hour.For consideration economically, the response time is preferably no more than 6 hours, more preferably no more than 4 hours, most preferably is no more than 3 hours.

The cross linked polymer that produces between polymerization period absorbs all aqueous reaction matter and forms hydrogel.Term hydrogel used herein refers to the swollen water liquid of water absorbable polymer.The water content of this polymer is at least about 10% of hydrogel weight.More typical is at least about 15%.In a specific embodiments, hydrogel other method drying the hot-air dry that during heating polymerization, exists in the reactor.When polyreaction was finished, the water content of hydrogel generally was in 50-80% (weight) scope.

The hydrogel that produces sieves and drying with method well known in the art is pre-.Pre-screening back gel particle size should be carried out particulate even drying.Pre-screening can be undertaken by known in the art any method that can provide expected result.Usually pre-screening is undertaken by the chopping hydrogel.In a specific embodiments, force gel by sieving in advance such as 497623 described mouthfuls of moulds of european patent application.When using through type circulation belt dryer, the hydrogel particle that obtains just is distributed on the conveyer belt that enters exsiccator.

In some cases, dryly divide two or more multistep is rapid.Two steps, the gel particle first step of screening part earlier was dry when dry, for example did to the amount of wetness that is lower than 10% preferably about 5%.During the preliminarily dried, hydrogel particle tends to the clinkering slabbing, and in the two-step type exsiccator, the exsiccant hydrogel sheet of part can be ground into 10cm * 10cm * 2cm small pieces roughly, these fractionlets are at the second step bone dry then, for example do to amount of wetness less than about 7%.Then, drying is finished, and small pieces sieve thinlyyer and form the granule of average diameter less than about 0.8mm.

Carry out exsiccant temperature should be enough high so that water and any organic solvent that uses in case of necessity can reasonably exclude with a kind of economic and practical method in the time.The temperature of water-absorbent besin particles is preferably about 180 ℃ or lower between dry period, and preferred temperature is 100-170 ℃, most preferably is 150-170 ℃.

Should be the water that is enough to remove desired amount in the rational time drying time, and it depends on used drying system.Usually drying will make the amount of wetness of hydrogel reduce to 1-5% (weight).Drying time will with drying equipment, sieve hydrogel size and drying equipment operating condition in advance and be associated.Because economically, drying time, be 10 minutes or longer drying time the shortest generally no longer than the essential time, 15 minutes or longer better.Be preferably drying time below 60 minutes, more preferably below 25 minutes.

Exsiccant water liquid absorbable polymer preferably stands the granule comminuting method of machinery, for example pulverizes, shreds and/or grind.Machinery granule comminuting method is used to reduce the water-absorbent besin particles size and forms acceptable particle size when finally using.In preferred pattern, water liquid absorbable polymer crushes and screens earlier, and is levigate then.In preferred specific embodiments, the mean particle size that obtains is less than about 2mm, more preferably less than about 0.8mm.The mean particle size that obtains is preferably at least about 0.04mm, more preferably at least about 0.07mm, most preferably is at least about 0.1mm.

In order to improve absorbent properties, dried particles can be according to PCT patent application 92/07611 described process heat treatment.Specifically, in order to improve the absorbability under the load, dried granule need heat the sufficiently long time.Heat treatment temperature is preferably at least about 170 ℃, more preferably at least 190 ℃, most preferably is at least 220 ℃.Damage for fear of finished product, heat treatment temperature be lower than about 250 ℃ better, be lower than about 240 ℃ better.

In implementing the inventive method, heat treatment exists the needs inhibitor.Just as used herein, term " inhibitor " refers to be removed free radical thereby can prevent that polymer from the material of chain lytic response or autoxidation reaction taking place in the presence of free radical and oxygen, or reduces the material of intermediate formation hydroperoxides base on polymer before causing chain interruption.Usually inhibitor is known in this area.The trade (brand) name tabular of commercially availabie inhibitor is in Kirk and Othmer Encyclopedia of Chemistry Vol.3, page 128-148.

Antioxidant is the subitem class of term " inhibitor ", and antioxidant is useful for stoping free radical and the reaction of the autoxidation between the oxygen on the polymer that can cause chain interruption.Antioxidant also has a purposes to be: they are polymer peroxides (before it causes chain interruption) of Reducing agent reduction intermediate formation in the autoxidation process.The tabular of typical antioxidant is in Ullrnann ' s Encyclopedia of Industrial Chemistry, Vol.3, page91ff, the Peter P.Klemchuk that delivers on VCH-VerlagsgselleschaftD-6940 Weinheim (FRG) .5. (complete-ly revised edition 1985) is on the article " antioxidant " of (Cida-Geigy company).

Representational inhibitor comprises hindered phenol, aromatic amine, sulphur compound, phosphorus compound or hindered amine, ascorbic acid and derivant thereof.Gallate and derivant, benzothiazole, thionic acid salt, thiuram, benzimidazole, formaldehyde sulfoxylate salt and phenothiazine.

The instantiation of inhibitor comprises ascorbic acid and its derivant (for example L-ascorbic acid, L-sodium ascorbate, arabo-ascorbic acid, sodium erythorbate); Gallate and derivant thereof (for example gallate, methyl gallate, ethyl gallate, gallate n-propyl, gallate isopentyl ester, misery ester, gallate lauryl, pyrogallol); Benzothiazole (for example mercaptobenzothiazoler, mercaptobenzothiazole sodium, mercaptobenzothiazole zinc); Dithionate (for example methyl curing carbaminate, (DDC)2Zn, zinc dibutyl dithiocaarbamate, ethylbenzene base zinc dithiocarbamate); Thiuram (for example dithio tetra methylthiuram, tetraethylthiuram disulfide, tetrabutylthiuram disulfide, tetramethylthiuram monosulfide); Benzimidazole (for example 2-mercaptobenzimidazole), formaldehyde sulfoxylate salt (for example sodium sulfoxylate formaldehyde) and phenothiazine (for example phenothiazine, 2-methoxyl group phenothiazine).

Other inhibitor has: as the sulphite of salt or acid, hydroquinone, p methoxy phenol, benzoquinone, methylnaphthohydroquinone, the methoxyl group hydroquinone, tertiary butylated hydroquinone, lignosulphonates, flavonoid (for example Tricetin and ellagic acid and salt thereof, phenolic compound (as cathecol), resorcinol and derivant and aminated compounds (as N-nitrosobenzene azanol ammonium salt), thiourea, tannin and salt thereof (as hydrolysis-type tannin that from nutgall, obtains and the condensed type tannin that from gambier, obtains), citric acid, 1,1-two (4-hydroxyl phenol)-cyclohexane extraction, β-naphthols, 2,6-ditertbutylparacresol, butylatedhydroxyanisole (hydroxyanisol), thiourea dioxide, thiodipropionic acid two lauryls and triphenyl phosphite.

These inhibitor can use separately also can coupling.If be used for private health protection articles for use, preferred inhibitors can be corresponding to as food stabilizer, as Yoshinox BHT, butylatedhydroxyanisole, 2-and 3-tert-butyl group-4-methoxyphenol or 3,4,5-Propylgallate (GAPE).Consider their typical performance, particularly preferred inhibitor comprises gallate derivant, for example GAPE.

Inhibitor will be before dry polymer be heat-treated or during provide.In a specific embodiment, before heat treatment, in polymer, use inhibitor after the polymer drying.In this specific embodiment, can use inhibitor with one of dual mode at least.A kind of mode is that inhibitor " is present in " in the water liquid absorbable polymer substantially equably, the water-soluble formation solution of inhibitor reinjects and is equipped with in the horizontal mixer of dry polymer, and inhibitor solution and polymer fully mix a period of time by this way makes inhibitor solution enter polymer beads inside.This method more detailed description is stated the example under the subhead " adding of inhibitor and dispersive process 1 " as follows.

Another kind of mode is inhibitor " height concentrates in water liquid absorbent polymer particles surface ", forms solution in inhibitor organic solvent water-soluble and that use in case of necessity such as the isopropyl alcohol, is added in the polymer beads then.This solution can contain surfactant and promote inhibitor in the lip-deep distribution of polymer beads.Polymer beads/inhibitor solution compositions is rolled, and the chien shih inhibitor solution contacts with the polymer beads surface when mixing long enough, and does not infiltrate granule interior substantially.This method more detailed description is stated the example under the subhead of " inhibitor add and distributed process 2 " (not using surfactant) and " inhibitor adding and distributed process 3 " (use polyoxyethylene-(2)-sorbitol lanoline (lanoline) derivant is made surfactant) as follows.

In another embodiment, before the polymerization after drying or during, inhibitor is added on the hydrogel.In this specific embodiments, form solution in the organic solvent that uses in case of necessity that inhibitor is water-soluble and isopropyl alcohol is such, then this solution is added on the hydrogel.During adding inhibitor, the hydrogel temperature preferably is higher than room temperature.Typical hydrogel temperature is between 30-60 ℃.Inhibitor solution also can contain surfactant and promote its distribution on the hydrogel particle surface.Dry then and heat treatment usefulness inhibitor solution treated water gel.The detailed description of this method sees that small tenon is entitled as the example of " adding of inhibitor and distributed process 4 ".

When inhibitor will concentrate in the polymer beads surface, it is better that the amount of inhibitor is at least about the heavy 5ppmw of polymer beads, and it is better to be at least about 25ppmw, best at least about 50ppmw.Equally, it is better that the inhibitor consumption is not greater than about 8000ppmw with the polymer beads restatement yet, and it is better to be not more than about 5000ppmw, and it is better to be not more than about 2000ppmw, and it is best to be not more than about 500ppmw.

When inhibitor during heating treatment is that it is better that the inhibitor consumption is at least about 50ppmw with the polymer beads restatement when being present in the polymer beads more equably, about 100ppmw is better.Equally, with the polymer beads restatement, the inhibitor consumption is not more than that about 5000ppmw is better, and it is better to be not more than 3000ppmw, and it is best to be not more than about 2000ppmw.

When after the polymerization, dry before or between dry period, when inhibitor was used for hydrogel, it is better that the amount of inhibitor is at least about 1000ppmw in hydrogel weight, about 2000ppmw is better.Equally, approximately 10000ppmw is not better for the inhibitor consumption, and it is better to be not more than about 8000ppmw.

Though do not think necessaryly concerning polymer properties, polymer of the present invention may contain remaining inhibitor, the inhibitor of promptly unreacted or partial reaction.Remaining inhibitor content is by using such as after the extraction of hydrophilic solvents such as water and methanol, and preparation detects with aliquot UV spectroscopic assay.The amount of the contained remaining inhibitor of common water liquid absorbable polymer of the present invention approximates half of the inhibition dosage that adds polymer.Consider the inhibitor content of recommendation, the pre-metering of remaining inhibitor often is 10-5000ppmw in water liquid absorbent weight in the polymer of the present invention.

In order to promote homogeneous to distribute, inhibitor preferably adds as liquid, when inhibitor is solid, often it is dissolved in the suitable solvent, such as water or water/ORGANIC SOLVENT MIXTURES.Typical organic solvent comprises such as methanol ethanol, normal propyl alcohol, isopropyl alcohol, n-butyl alcohol, the lower alcohol that the isobutanol and the tert-butyl alcohol are such; Such as acetone, the ketone that butanone and methylisobutylketone are such; Such as diethyl ether, diisopropyl ether, dipropyl ether, butyl oxide, the ether of ethyl isopropyl ether and so on; Cyclic ethers such as dioxanes and this class of oxolane; Such as N, the amide that N-dimethyl formamide is such and such as the such sulfoxide of dimethyl sulfoxine.For making inhibitor dissolving, but heated solvent is to required degree.

Inhibitor solution can also contain surfactant in case of necessity.Exemplary surfactants is in 3-10 scopes and the nonionic surfactant that can be scattered in water of HLB value.Preferred surfactants has: fatty acid esters of sorbitan, polyoxyethylene fatty acid esters of sorbitan, glycerol or polyglyceryl fatty acid ester, polyoxyethylene alkyl ether, polyoxyethylene alkyl phenolic ester, the polyoxyethylene acrylate, the surface activity polyester of fatty acid cane sugar ester or modification.Preferred surfactant is a polyethoxylated sorbitol lanolin derivative, for example can be from ICI Specialty Chemicals (polyoxyethylene-(2)-sorbitol lanolin derivative of the commodity that United Kingdoms buys G1425 by name.When using surfactant, often with 0.01-2 parts amount in per 100 parts of heavy water liquid absorbent resins, more preferably 0.075-0.5 part amount exists in solution for it.

In case of necessity, exist degree not influence at it and have centrifugal capacity of 25g/g and 70000 dynes per centimeter at least ²(1.0psi) at least under the condition of the formation of the polymer of the present invention of 15g/gAUL, during Technology for Heating Processing, wherein can there be chloric acid, bromic acid or its salt, for example, when water liquid absorbable polymer is crosslinked with the trimethylolpropane triacrylate of height ethoxylation, add chloric acid, bromic acid or its salt are useful.

The equilibrium ion of bromate or chlorate can be any equilibrium ion of not serious interference resin particle preparation or its performance.Preferred equilibrium ion is alkaline-earth metal ions or alkali metal ion.Preferred equilibrium ion is an alkali metal ion, potassium, and sodium is better, and chloric acid or its salt are most preferred.

Work as chloric acid, when bromic acid or its salt directly are added on reactant mixture, preferred consumption is with ethylenically unsaturated monomer that exists and the total restatement of comonomer that uses in case of necessity, be at least about 10ppm, more preferably at least about 50ppm, even, most preferably be at least about 200ppm more preferably at least about 100ppm.Work as chloric acid, when bromic acid or its salt directly were added on reactant mixture, preferred consumption was less than about 1000ppm with ethylenically unsaturated monomer that exists and the total restatement of comonomer that uses in case of necessity, more preferably is less than about 600ppm, most preferably was to be less than about 500ppm.

Heat treated temperature and time interval should be enough to influence the improvement of absorbent properties, and heat treated exact temperature and time will be influenced by selected device will, is according to deciding with the experiment by the test of properties of product.The heating resin particle keeps this temperature until 1.0psi (70000 dynes per centimeter to the post-heating temperature of expectation ²) AUL increases to 15g/g at least.Heat treatment temperature is preferably at least 180 ℃, more preferably at least 200 ℃, most preferably is at least 220 ℃.For avoiding damaging polymer, heat treatment temperature is preferably lower than 250 ℃.

Resin particle often maintains desired temperatures 1 minute or longer, is preferably 5 minutes or longer.If the processing time is long, uneconomical economically, and resin particle has the danger of damaged, and general resin particle keeps being preferably below 40 minutes, more preferably below 30 minutes below 60 minutes in desired temperatures.

Heat treatment can be finished with method well known in the art, for example forces baking oven, and fluid bed heater and heating spiral rod formula carrier all can successfully use.If desired, Re polymer can be moistening again so that handle.In a preferred specific embodiments, heat treated granule contacts in fluid bed with water vapour, dried granule contacts with enough water to reduce or eliminate electrostatic interaction, but it is not many to causing that granule condenses yet, dried granule is preferably with 0.3% or more (weight), more preferably 1% (weight) or more water humidification, dried simultaneously granule is preferably below about 10% (weight), more preferably the following water humidification of 6% (weight).

Also can in the crosslinking hydrophilic resin, add in case of necessity and prevent the additive that condenses.This class additive is well known in the art, and it comprises the inert inorganic granule, as Silicon stone, and referring to US4500670,4286082,4734478 and Deutsche Bundespatent 2706135.

Form for final sizing stage of being reduced in polymeric articles is normal not in conjunction with content of dust (for example mean particle size is less than 10 microns not bound water liquid absorbent polymer particles) and/or unconjugated dust in order to suppress to form in the polymer treatment process, dedusting agent and heat treated article can be mixed together.The use of this dedusting agent sees PCT patent application 93/02872.As described herein, typical dedusting agent comprises water solublity, and mean molecule quantity is 400-6000 rudimentary poly alkylene glycol greater than about 200 lower aliphatic polyhydric alcohol or mean molecule quantity.Propylene oxide adduct that a kind of preferred dedusting agent is a glycerol or mean molecule quantity are 500-2000 Polyethylene Glycol.Specifically, typical dedusting agent comprises VO-RANOL ^TMPolyether polyol (VORANOL for example ^TM2070, VORANOL ^TM2100 and VORANOL ^TM3100 polyether polyol) (all can buy) from The Dow Chemical Company; Polyethylene Glycol, glycerol, polyether alcohol (DOWANOL for example ^TMTPM tripropylene glycol methyl ether, DOWANOL ^TMTPnB tripropylene glycol n-butyl ether and DOWANOL ^TMPPH propylene glycol phenylate) (buys) by The Dow Chemical Company; TRITON ^TMX-100 surfactant (can buy) by Union Carbide; TERGITOL ^TM15-S-9 ethoxylated surfactant (can available from Union Carbide); Be at least 7 non-ionic surface agent with the HLB value.

When using dedusting agent, consumption is preferably 100-5000ppm (weight) with the polymer beads restatement, more preferably 300-3000ppm (weight).Dedusting agent can apply by the form of certain mechanical distribution, so that dedusting agent has suitable distribution on water liquid absorbent polymer particles.Mixing apparatus/craft embodiment comprises: simple pot type rotary drum or at the taper exsiccator, mix in ribbon mixer or the turning barrel, the stirring of appropriateness, concussion in addition the short-and-medium square of helical conveyor from conveying all enough for the suitable distribution of dedusting agent on granule, when granule be higher than under the temperature of room temperature particularly like this.

Though describe, also may utilize the heterogeneous polymerization Technology to carry out polymerization process, for example inverted emulsion polymerization or contrary suspension polymerisation process according to the gel polymerisation technology.In inverted emulsion or contrary suspension polymerisation process, aqueous reaction mixture as previously mentioned water immiscibility such as cyclohexane extraction or with the blended ISOPAR of hydrocarbon ^TMMicrodroplet form in the substrate of inert organic solvents such as (available from Exxon) suspends.Sometimes inverted emulsion polymerization and contrary suspension polymerisation process are favourable, and they can control the heat release of polyreaction preferably, and can have the mode of control to add one or more aqueous reaction mixture compositions to organic facies with a kind of neatly.

Contrary suspension polymerisation process is described in greater detail in US4340706 and 4506052 and PCT patent application 92/07336.When using contrary suspension or inverted emulsion polymerization technique, additional such as surfactant, components such as emulsifying agent and polymerization stabilizer can be added in the entire reaction mixture.For example US4708997 and 4833198 discloses preferred stabilizing agent and its application in process for suspension polymerization, and this stabilizing agent contains the mixture of lauryl methacrylate and acrylic acid copolymer and Silicon stone.

When using any with an organic solvent technology, water liquid absorbent polymeric material needs treated to remove all excessive organic solvents substantially.Residual organic solvents in the water liquid absorbable polymer is no more than about 0.5% (weight) preferably.

Water-absorbent besin particles of the present invention can be used for any requirement absorption and bound water base fluid part.In a preferred specific embodiments, on sneaking into or be attached to structure such as the absorbing material of synthetic or natural fiber or paper substrate weaving or non-woven fibre, water-absorbent besin particles of the present invention forms a kind of structure.In this structure, weaving or non-woven constructions role are a kind of approach that absorbs or carry, and through capillarity, Liquid Absorption has arrived on the water-absorbent besin particles of combination and liquid hold-up.This class absorbent structure is usually used in absorbing products, as diaper, adult-incontinence articles and sanitary towel.

Typical absorbing products comprises liquid-tight backing material, saturating liquid level material and sandwich absorbent structure in the middle of them.Absorbent structure often comprises fibrous matrix (as the fluffy hair of inflation batt, discuss according to Mazurak and Fries, form) as the US4381782 statement.The suitable fiber that is used for this fibrous matrix comprises ground wood pulp, linter and fusion porous synthetic fiber, polyethylene for example, polypropylene, polyester, the copolymer of polyester and polyamide.Absorbing structure often contains the water liquid absorbent material of the present invention of 5-90% (weight), and all the other are the absorbent structures that comprise fibrous matrix.US5147343 provides a kind of absorbent structure that shows low seepage.Therefore, in the specific embodiments of a preferred absorbent structure of the present invention, the big young pathbreaker of water liquid absorbent particles is such: when humidity, its diameter has surpassed the medium pore size of porous fibre substrate.Particle diameter is only greater than 150 microns more preferably greater than 100 microns.

The present invention is further illustrated for following examples, but do not limit the claim scope.Unless otherwise mentioned, all umbers and percentage ratio are all by weight.Remove other and explain 60 minutes 21000 dynes per centimeter ²(0.3psi) AUL is as mensuration as described in the US5147343,60 minutes 42000 dynes per centimeter ²(0.6psi) with 60 minutes 70000 dynes per centimeter ²(1.0psi) all corresponding similarly adjustment testing time of AUL and pressure and measure; Centrifugal capacity is as mensuration as described in the US4286082, only is to use 30 minutes soak times rather than 3-5 minutes; Can extract content in 16 hours and issue mensuration as described in the patent 32649 again as US; Residual monomer content is as mensuration as described in the GB9304857 that submitted on March 10th, 1993.

Embodiment

The resins process

In 200 liters of polymer reactors of high torque (HT) stirring motor that rustless steel agitator and band gear reduction unit be housed, prepare sample.This device can pulverize the gel that forms between polymerization period, and chuck is a hollow, and using independently, the recirculated water temperature controlling instruments can heat or the cooling reactor content.Reactor seals, and links to each other with vacuum system, can the cooling gel piece by evacuation.

At one independently in the container, 37.2kg acrylic acid slowly is added in the mixture that contains 40.1kg50% sodium hydrate aqueous solution and 77kg fresh water (FW) forms premix, prevent that temperature rise from surpassing 38 ℃.VERSENEX with 70g40% (weight) ^TMThe polyvinyl alcohol that the living solution of 80 diethylentriamine pentacetate chelating agen (trade mark of The Dow Chemical Company) and 13g are dissolved in the partial hydrolysis in the 130ml pure water is added in the pre-composition, makes pre-composition be chilled to room temperature then.The type pointed out in the table 1 and the cross-linking agent of content are added in the 15.9kg pure acrylic acid, and the mixture that obtains adds chilled pre-composition again.In acrylic monomers weight, the 305ppmw potassium chlorate that uses is in case of necessity added the mixture that has just obtained form monomer mixture.

The monomer mixture for preparing is with being pumped in the reactor of crossing with purging with nitrogen gas.900g10% sodium peroxydisulfate aqueous solution and the active hydrogen peroxide of 68g30% (weight) are added in the reactor with syringe.In order to remove oxygen, the evacuation secondary.Space on the reactor liquid level is full of nitrogen.Adding 8g is dissolved in the ascorbic acid initiation reaction in the 80ml water.When polyreaction began, external heater was set at 70 ℃.Reaction arrives after the temperature peak (about 80 ℃), evacuation makes reactor cooled to 70 ℃, gel is retained in the reactor one hour in 70 ℃, shift out reactor then, chopping, with dry 20 minutes of 170 ℃ air flow, the part of gained dry products ground on breadboard mill, sieves into 30-50 orders then in banded exsiccator.

Table 1 column data provides the character that has before the resin formula that uses and the heat treatment in various experiments.

Table I

Character before the prescription of resin and the heat treatment

The experiment number	The cross-linking agent type	Dosage of crosslinking agent (ppmw)	Chlorate consumption (ppmw)	Centrifugal capacity	??0.3psi?AUL ????(g/g)	Extractable (%)	Residual monomer (ppm)
								????1	Allyl methacrylate	?????4000	?????0	?????27.3	?????26.3	?????4.9	????715
????2	Allyl methacrylate	?????3500	????305	?????26.1	?????24.3	?????5.6	????590
								????3	Allyl methacrylate	?????3000	????305	?????30.5	?????17.5	?????8.6	????314
????4	Allyl methacrylate	?????4000	????305	?????33.2	?????12.4	?????ND	????ND
								????5	?HE?TMPTA	?????4000	????305	?????37.3	??????9.7	????12.5	????311
????6	?HE?TMPTA	?????3000	????305	?????40.9	??????9.7	????14.7	????335
								????7	?HE?TMPTA	?????3000	?????0	??????36	??????8.7	????10.0	????497
????8	?HE?TMPTA	?????8000	????305	?????31.5	?????21.6	?????6.8	????463
								????9	?HE?TMPTA			?????37.3	?????10.7	????11.7	????335
???10	?HE?TMPTA			?????40.0	?????11.5	????14.1	????303

Inhibitor adds and distributed process 1:

With the exsiccant water liquid of 0.5kg absorbable polymer, as described in Table 1 being put in the horizontal mixer that cumulative volume is 3.2L, the chuck that this agitator has heating and cooling to use, and the axle of band agitation as appropriate device is housed, one cover vacuum and condensing unit and internal diameter are the syringe of 3mm, with product by heating to 120 ℃, at this moment, it is with 38 rev/mins rotating speed continuous stirring.In the another beaker, the inhibitor (in dry polymer 2000ppmw) of 1g expectation is dissolved in the 75ml water, under the situation of gallate propionic ester (GAPE), for complete dissolution inhibitor with hydro-thermal to 70 ℃, inhibitor solution slowly is injected into the top of product in the blender of closing via syringe.The moisture of inhibitor solution evaporates at once, has accumulated suitable pressure in airtight blender.After inhibitor solution added, product kept 45 minutes at 120 ℃, continued this moment to stir with scattered inhibitor, and made it diffuse into particulate core.Be evacuated to then 50 millibars 2-5 minutes, remove unnecessary water, product is chilled to 40 ℃, shift out blender.The adding of inhibitor and distributed process 2: as described in Table 1, with the exsiccant water liquid of 50g absorbable polymer in vial with the inhibitor of 50mg expectation, the solution of 4g isopropyl alcohol and 2g standard chamber warm water mixes by means of spatula, and the mixture that obtains mixed on roller press 15 minutes.Inhibitor adds and distributed process 3:

As described in Table 1, with the exsiccant water liquid of 50g absorbable polymer in a vial with solution and 50mg polyoxyethylene-(2)-sorbitol lanolin derivative (ICI Specialty Chemicals Goldschmidtstrasse 100 of consumption propyl gallate (AGPE) inhibitor, 4g isopropyl alcohol and 3.75g standard chamber warm water as shown in Table V, Fssen, Germany, sell with G-1425 trade mark), mix by means of spatula, the mixture that obtains mixed on roller press 15 minutes.The adding of inhibitor and distributed process 4:

With standard recipe and polymerization process, use HE-TMPTA and the 265ppm chlorate of 5800ppmw to prepare hydrogel.After the polymerization, the chopping gel.Be preferably under the temperature that is higher than 50 ℃, the broken gel of every 1kg with by the GAPE of respective amount, 70ml water, 30ml isopropyl alcohol with count the solution that 2000ppmw polyoxyethylene-(2)-sorbitol lanolin derivative (ICI Specialty Chemicals sells with G-1425 trade mark) forms with the gel gross weight and be mixed together.The treated water gel continues on conveyer belt 170 ℃ of dryings like this.Heat treatment process: earlier with zone of hot-air spray gun preheating, in case reach target temperature shown in Table II, III, IV and the V and stable after, sample is put into this district, a contact thermometer is inserted and contact with sample, the monitoring sample temperature is stabilized on the target temperature until it.Sample is in this target temperature maintenance time shown in Table II, III, IV and V then.

Table II institute column data is suitable for using methoxyl group hydroquinone (MEHQ) to make inhibitor, and adds with the method for inhibitor adding and distributed process 1, and wherein inhibitor is present in the polymer beads more equably.Table III institute column data is suitable for using gallate propyl ether (GAPE) to make inhibitor, and with the method adding of inhibitor adding and distributed process 1, wherein inhibitor is present in the polymer beads more equably.Table IV institute column data is suitable for using propyl gallate (GAPE) to make inhibitor, and with the method adding of inhibitor adding and distributed process 2, wherein the inhibitor height concentrates in the polymer beads surface.Table V institute column data is suitable for making inhibitor with propyl gallate (GAPE), and with the method adding of inhibitor adding and distributed process 3, wherein GAPE is higher concentrates in the polymer beads surface, and the amount of GAPE changes.Table VI institute column data is inhibitor with GAPE, and with the method adding of inhibitor adding and distributed process 4, wherein inhibitor added hydrogel before gel drying.

Table II

Method with inhibitor adding and distributed process 1 adds 2000ppmw MEHQ inhibition

Agent (in polymer weight)

Sample	Heat-treat condition (℃/min.)	Centrifugal capacity (g/g)	??0.3psi?AUL ????(g/g)	??0.6psi?AUL ????(g/g)	????1.0psi?AUL ???????(g/g)	Extractable (%)	Residual monomer (ppm)
								The 1-contrast *	????200/10	????30.9	????29.4	?????12.7	????????9.1	????4.8	????781
??????1a	????200/10	????28.8	????28.7	?????25.6	???????17.8	????4.8	????648
								??????1b	????210/10	????29.3	????28.6	?????25.5	???????16.0	????4.9	????743
??????1c	????220/10	????28.7	????27.5	?????25.3	???????20.6	????4.6	????758
								The 5-contrast *	????200/10	????38.9	????30.3	?????11.9	????????8.3	????9.7	????395
??????5a	????200/10	????37.0	????30.6	?????20.7	????????9.9	???11.0	????251
								??????5b	????210/10	????37.0	????30.3	?????22.2	???????12.2	???10.7	????299
??????5c	????220/10	????36.9	????31.2	?????24.6	???????15.3	???12.4	????253
								7-contrast-1 *	????200/5	????31.1	????29.5	?????17.4	????????9.1	????7.8	????503
??????7a	????200/5	????25.2	????26.0	?????23.0	???????20.5	????3.9	????453
								7-contrast-2 *	????220/15	????27.7	????27.7	?????24.3	???????12.4	????6.1	????563
??????7b	????220/15	????21.9	????23.5	?????20.4	???????18.2	????2.4	????488

^*In various contrast sample, do not use MEHQ

Table III

Method with inhibitor adding and distributed process 1 adds 2000ppmw GAPE inhibition

Agent (in polymer weight)

The experiment number	Heat-treat condition (℃/min.)	Centrifugal capacity (g/g)	??0.3psi?AUL ????(g/g)	??0.6psi?AUL ????(g/g)	?1.0psi?AUL ????(g/g)	Extractable (%)	Residual monomer (ppm)
								The 1-contrast *	???200/10	????30.9	?????29.4	?????12.7	?????9.1	????4.8	????781
????1d	???200/10	????28.3	?????28.7	?????25.7	????21.2	????4.7	????651
								????1e	???210/10	????28.2	?????28.0	?????25.3	????21.0	????4.1	????694
????1f	???220/10	????27.5	?????27.3	?????24.9	????22.3	????3.6	????758
								The 4-contrast *	???200/10	????34.6	?????28.2	?????10.7	?????7.7	????9.7	????555
????4d	???200/10	????31.5	?????30.4	?????25.2	????18.6	????7.1	????432
								????4e	???210/10	????31.3	?????30.7	?????25.9	????21.6	????6.6	????412
????4f	???220/10	????30.7	?????29.8	?????26.1	????23.1	????7.1	????380
								The 5-contrast *	???200/10	????38.9	?????30.3	?????11.9	?????8.3	????9.7	????395
????5d	???200/10	????32.7	?????31.1	?????25.2	????15.2	????7.0	????491
								????5e	???210/10	????32.0	?????31.1	?????26.0	????20.7	????6.3	????458
????5f	???220/5	????32.8	?????30.5	?????26.3	????19.9	????7.2	????418
								????5g	???220/8	????31.2	?????29.5	?????26.8	????22.0	????6.7	????428
????5h	???220/10	????30.6	?????29.8	?????26.3	????22.4	????6.8	????420
								????5i	???220/15	????29.9	?????29.1	?????25.6	????22.7	????6.6	????418
????5j	???220/20	????29.3	?????27.5	?????25.3	????22.4	????7.2	????380

^*At each contrast sample, do not use GAPE

Table IV

Method with inhibitor adding and distributed process 2 adds 1000ppmw (with polymer weight

Meter) GAPE suppresses

The experiment number	Heat-treat condition (℃/min)	Centrifugal capacity (g/g)	?0.3(psi?AUL ????(g/g)	??0.6psi?AUL ?????(g/g)	??1.0psi?AUL ?????(g/g)	Extractable (%)	Residual monomer (ppm)
								????2a	????210/15	???37.4	?????32.5	?????25.4	?????14.6	????17.9	????611
????3a	????210/15	???32.9	?????32.9	?????25.5	?????19.8	????11.4	????388
								The 5-contrast *	????200/10	???38.9	?????30.3	?????11.9	??????8.3	?????9.7	????395
????5k	????220/5	???37.9	?????35.4	?????28.1	?????17.5	????11.0	????427
								????5l	????220/8	???36.8	?????34.4	?????29.2	?????22.4	????10.3	????344
????5m	????220/10	???34.6	?????34.0	?????28.2	?????22.6	????10.3	????346
								????5n	????220/15	???34.0	?????32.1	?????27.1	?????22.1	????12.0	????317
????5o	????220/20	???32.3	?????30.9	?????25.8	?????20.9	????14.2	????292
								????5p	????230/8	???36.4	?????34.7	?????28.1	?????23.7	????13.2	????389
????8a	????220/8	???31.0	?????31.0	?????26.8	?????23.0	?????6.0	????361
								????8b	????230/8	???31.8	?????31.9	?????26.5	?????23.2	?????6.8	????350

^*In the contrast sample, do not use GAPE

Table V

Method with inhibitor adding and distributed process 3 adds the GAPE inhibitor

Sample	Heat-treat condition (℃/min)	GAPE concentration (ppm is in polymer)	Centrifugal capacity (g/g)	???0.3psi ??AUL(g/g)	??0.6psi ??AUL(g/g)	???1.0psi ??AUL(g/g)	Extractable (%)	Residual monomer (ppm)
									The 6-contrast *	???220/8	???????0	????41.6	????28.3	????11.8	?????7.9	????13.1	????483
???6a	???220/8	??????50	????36.2	????34.9	????30.0	????25.2	????19.6	????436
									???6b	???220/8	?????100	????35.8	????34.6	????30.4	????24.8	????20.0	????436
???6c	???220/5	?????200	????38.4	????36.6	????30.5	????25.2	????17.1	????456
									???6d	???220/8	?????200	????35.6	????35.6	????30.3	????25.5	????17.3	????462
???6e	???220/10	?????200	????35.3	????35.5	????29.7	????25.9	????17.3	????453
									???6f	???220/15	?????200	????34.2	????33.9	????28.9	????25.7	????16.4	????429
???6g	???220/20	?????200	????32.5	????32.6	????28.7	????25.1	????15.5	????400
									???6h	???220/8	?????500	????36.2	????35.5	????30.0	????25.4	????16.9	????448
???6i	???220/8	????2000	????36.4	????34.2	????28.5	????23.8	????18.7	????457
									???6j	???220/8	????5000	????36.1	????33.4	????27.4	????22.5	????18.2	????461

^*In the contrast sample, without GAPE

Table VI

Method with inhibitor adding and distributed process 4 adds the GAPE inhibitor

Sample	Heat-treat condition (℃/min)	GAPE concentration (ppm is in polymer)	G1425 (ppm is with gelometer)	Centrifugal capacity (g/g)	???0.3psi ?????AUL ????(g/g)	??0.6psi ???AUL ??(g/g)	????1.0psi ?????AUL ????(g/g)	Extractable (%)	Residual monomer (ppm)
										9-contrast-1	Do not have	Do not have	????2000	????37.3	????10.7	????8.0	?????ND	???11.7	????335
9-contrast-2	Do not have	????1000	????2000	????36.6	????12.5	????8.7	?????ND	???11.3	????236
										9-contrast-3	Do not have	????2000	????2000	????36.8	????15.2	????7.4	?????ND	???11.6	????296
9-contrast-4	Do not have	????5000	????2000	????36.3	????12.2	????8.6	?????ND	???11.6	????296
										9-contrast-5	???210/20	Do not have	????2000	????40.0	????32.4	???21.4	?????11.1	???13.4	????355
?????9a	???210/20	????1000	????2000	????34.6	????31.5	???25.7	?????14.8	???10.9	????407
										?????9b	???210/20	????2000	????2000	????32.5	????30.4	???23.8	?????16.6	????9.3	????493
?????9c	???210/20	????5000	????2000	????32.4	????30.3	???25.9	?????15.6	????9.3	????546
										10-contrast-1	Do not have	Do not have	Do not have	????40.0	????11.5	????8.3	?????ND	???14.1	????303
10-contrast-2	Do not have	????1000	Do not have	????37.3	????19.7	????8.9	?????ND	???11.4	????350
										10-contrast-3	Do not have	????2000	Do not have	????35.3	????13.4	????8.5	?????ND	????9.4	????292
10-contrast-4	Do not have	????5000	Do not have	????33.8	????14.7	????8.6	?????ND	????8.7	????349
										10-contrast-5	???210/20	Do not have	Do not have	????37.9	????32.2	???21.8	?????11.1	???14.2	????387
?????10a	???210/20	????1000	Do not have	????32.9	????30.2	???24.3	?????13.9	????9.0	????467
										?????10b	???210/20	????2000	Do not have	????30.9	????29.7	???25.4	?????15.8	????8.0	????561

Table VI (continuing)

Sample	Heat-treat condition (℃/min.)	GAPE concentration (ppm is in polymer)	G1425 (ppm is with gelometer)	Centrifugal capacity (g/g)	??0.3psi ????AUL ???(g/g)	??0.6psi ???AUL ??(g/g)	??1.0psi ???AUL ??(g/g)	Extractable (%)	Residual monomer (ppm)
										???10c	????210/20	????5000	???none	????29.7	???29.8	???25.9	???21.1	???7.8	???700

Other specific embodiments of the present invention all will be determined by those of ordinary skill in the art at an easy rate.Therefore, scope of the present invention is only limited by following claim.

Claims (21)

1. contain ethylenically unsaturated monomer and use in case of necessity can with the water liquid absorbable polymer of the polymerizate of the comonomer of ethylenically unsaturated monomer copolymerization, this water liquid absorbable polymer is crosslinked with the cross-linking agent that has two active parts that can react with ethylenically unsaturated monomer and the comonomer that uses in case of necessity at least, and wherein this water liquid absorbable polymer is characterised in that: centrifugal capacity is at least 25g/g and in 70000 dynes per centimeter ²(1.0psi) absorption under the load is at least 15g/g.

2. the water liquid absorbable polymer of claim 1, wherein the feature of water liquid absorbable polymer also is: the content that can extract polymer is lower than 18%.

3. the water liquid absorbable polymer of claim 1, wherein, water liquid absorbable polymer is characterised in that: centrifugal capacity is at least 30g/g and in 70000 dynes per centimeter ²(1.0psi) absorption under the load is at least 20g/g.

4. the water liquid absorbable polymer of claim 1, wherein, water liquid absorbable polymer is characterised in that: centrifugal capacity is at least 35g/g, in 70000 dynes per centimeter ²(1.0psi) absorption under the load is at least 25g/g.

5. the water liquid absorbable polymer of claim 1, wherein, the feature of water liquid absorbable polymer also is: the amount of remaining inhibitor is counted 10-5000ppmw with polymer and remaining inhibitor weight.

6. the method for preparing water liquid absorbable polymer comprises following step:

A) with ethylenically unsaturated monomer and use in case of necessity can with the comonomer of ethylenically unsaturated monomer copolymerization have at least can with polymerization formation water liquid absorbability pearl or hydrogel in the presence of the cross-linking agent of two active parts of ethylenically unsaturated monomer and the comonomer that uses in case of necessity reaction;

B) solvent or the water in the hydrogel that removes in the liquid absorbability pearl of anhydrating forms dry water liquid absorbent polymeric material; With

C) this dry water liquid absorbent polymeric material of heat treatment forms heat treated water liquid absorbent polymeric material under 180-240 ℃ temperature; Wherein, this dry water liquid absorbent polymeric material contains inhibitor during the heat treatment of step (c), and this inhibitor provides after the polymerization of step (a) and before the heat treatment of step (c).

7. the method for claim 6, wherein, inhibitor is present in the exsiccant water liquid absorbent polymeric material during the heat treatment of step (c) substantially equably.

8. the method for claim 7, wherein, the amount of inhibitor is counted 100-5000ppmw with the weight of dry water liquid absorbent polymeric material.

9. the method for claim 6, wherein, inhibitor height during the heat treatment of step (c) concentrates in the particle surface of dry water liquid absorbent polymeric material.

10. the method for claim 9, wherein, the amount that is present in the inhibitor in the dry water liquid absorbent polymeric material is about 25-8000ppmw in dry water liquid absorbent polymeric material weight.

11. the method for claim 9, wherein, the amount that is present in the inhibitor in the dry water liquid absorbent polymeric material is about 25-500ppmw in dry water liquid absorbent polymeric material weight.

12. the method for claim 6, wherein inhibitor added in the hydrogel before the removing step of step (b).

13. the method for claim 12 wherein provides the weight of the amount of inhibitor in water liquid absorbability pearl or hydrogel, is about 1000-10000ppmw.

14. the method for claim 6, wherein, inhibitor is a sulphite, phenol, arylamine, organosulfur compound, phosphorus compound or hindered amine, ascorbic acid or derivatives thereof, gallate or derivatives thereof, benzothiazole, dithionate, thiuram, benzimidazole, formaldehyde sulfoxylate salt or phenothiazine.

15. the method for claim 6, wherein, inhibitor is the gallate or derivatives thereof, quinone or derivatives thereof or hydroquinone or derivatives thereof.

16. the method for claim 6, wherein, inhibitor is a propyl gallate.

17. the method for claim 6, wherein, cross-linking agent is the trimethylolpropane triacrylate of height ethoxylation, inhibitor is propyl gallate or methoxyl group hydroquinone, and wherein chlorate that uses in case of necessity or bromate are added in the exsiccant water liquid absorbent polymeric material after the polymerization of step (a) and before the heat treatment of step (c).

18. the method for claim 6, wherein, cross-linking agent is an allyl methacrylate, and inhibitor is propyl gallate or methoxyl group hydroquinone; When inhibitor was propyl gallate, wherein, chlorate or bromate added in the exsiccant water liquid absorbent polymeric material after the polymerization of step (a) and before the heat treatment of step (c) in case of necessity.

19. contain the absorbent structure of fibre substrate and water liquid absorbable polymer, the feature of this water liquid absorbable polymer is: centrifugal capacity is at least 25g/g, in 70000 dynes per centimeter ²(1.0psi) absorption under the load is at least 15g/g.

20. the absorbent structure of claim 19, wherein, water liquid absorbable polymer is characterised in that: centrifugal capacity is 30g/g at least, in 70000 dynes per centimeter ²(1.0psi) absorption under the load is at least 15g/g.

21. the absorbing structure of claim 19, wherein, water liquid absorbable polymer is characterised in that: centrifugal capacity is at least 35g/g, in 70000 dynes per centimeter ²(1.0psi) absorption under the load is at least 25g/g.