EP1636291A1 - Esters (meth)acryliques de glycols alkylene-ylene et leur utilisation - Google Patents

Esters (meth)acryliques de glycols alkylene-ylene et leur utilisation

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Publication number
EP1636291A1
EP1636291A1 EP04736051A EP04736051A EP1636291A1 EP 1636291 A1 EP1636291 A1 EP 1636291A1 EP 04736051 A EP04736051 A EP 04736051A EP 04736051 A EP04736051 A EP 04736051A EP 1636291 A1 EP1636291 A1 EP 1636291A1
Authority
EP
European Patent Office
Prior art keywords
ester
reaction mixture
weight
meth
acrylic acid
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP04736051A
Other languages
German (de)
English (en)
Inventor
Ulrich Riegel
Thomas Daniel
Matthias Weismantel
Mark Elliott
Rüdiger Funk
Reinhold Schwalm
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
BASF SE
Original Assignee
BASF SE
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Filing date
Publication date
Priority claimed from PCT/EP2003/005953 external-priority patent/WO2003104300A1/fr
Priority claimed from DE2003158369 external-priority patent/DE10358369A1/de
Application filed by BASF SE filed Critical BASF SE
Publication of EP1636291A1 publication Critical patent/EP1636291A1/fr
Withdrawn legal-status Critical Current

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Classifications

    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
    • C08G65/00—Macromolecular compounds obtained by reactions forming an ether link in the main chain of the macromolecule
    • C08G65/02—Macromolecular compounds obtained by reactions forming an ether link in the main chain of the macromolecule from cyclic ethers by opening of the heterocyclic ring
    • C08G65/32—Polymers modified by chemical after-treatment
    • C08G65/329—Polymers modified by chemical after-treatment with organic compounds
    • C08G65/331—Polymers modified by chemical after-treatment with organic compounds containing oxygen
    • C08G65/332—Polymers modified by chemical after-treatment with organic compounds containing oxygen containing carboxyl groups, or halides, or esters thereof
    • C08G65/3322—Polymers modified by chemical after-treatment with organic compounds containing oxygen containing carboxyl groups, or halides, or esters thereof acyclic
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
    • C08G65/00—Macromolecular compounds obtained by reactions forming an ether link in the main chain of the macromolecule
    • C08G65/02—Macromolecular compounds obtained by reactions forming an ether link in the main chain of the macromolecule from cyclic ethers by opening of the heterocyclic ring
    • C08G65/26—Macromolecular compounds obtained by reactions forming an ether link in the main chain of the macromolecule from cyclic ethers by opening of the heterocyclic ring from cyclic ethers and other compounds
    • C08G65/2603—Macromolecular compounds obtained by reactions forming an ether link in the main chain of the macromolecule from cyclic ethers by opening of the heterocyclic ring from cyclic ethers and other compounds the other compounds containing oxygen
    • C08G65/2606—Macromolecular compounds obtained by reactions forming an ether link in the main chain of the macromolecule from cyclic ethers by opening of the heterocyclic ring from cyclic ethers and other compounds the other compounds containing oxygen containing hydroxyl groups
    • C08G65/2609—Macromolecular compounds obtained by reactions forming an ether link in the main chain of the macromolecule from cyclic ethers by opening of the heterocyclic ring from cyclic ethers and other compounds the other compounds containing oxygen containing hydroxyl groups containing aliphatic hydroxyl groups

Definitions

  • the present invention relates to new (meth) acrylic esters of polyalkoxylated glycols, a simplified process for the preparation of these esters and use of the reaction mixtures thus obtainable.
  • Superabsorbents Swellable hydrogel-forming polymers, so-called superabsorbents (Super Absorbing Polymers, SAP), are known from the prior art. These are networks of flexible hydrophilic polymers, which can be both ionic and nonionic in nature. These are able to absorb and bind aqueous liquids to form a hydrogel and are therefore preferred for the production of tampons, diapers, sanitary napkins, incontinence articles, training underwear for children, shoe insoles and other hygiene articles in the absorption of body fluids. Superabsorbers are also used in other areas of technology in which liquids, in particular water or aqueous solutions, are absorbed.
  • These areas are, for example, storage, packaging, transport (packaging material for water-sensitive articles such as flower transport, shock protection); Food sector (transportation of fish, fresh meat; absorption of water, blood in fresh fish / meat packaging); Medicine (wound plasters, water-absorbing material for burn dressings or for other wetting wounds), cosmetics (carrier material for pharmaceutical chemicals and medicines, rheumatic plasters, ultrasound gel, cooling gel, cosmetic thickener, sun protection); Thickeners for oil / water or water / oil emulsions; Textiles (gloves, sportswear, moisture regulation in textiles, shoe inserts); chemical process industry.
  • the superabsorbers are usually located in the so-called absorbent core, which includes fibers (cellulose fibers), which, as a kind of liquid reservoir, temporarily store the spontaneously applied amounts of liquid and ensure that the body fluids in the absorbent core are channeled to the superabsorber should guarantee.
  • absorbent core which includes fibers (cellulose fibers), which, as a kind of liquid reservoir, temporarily store the spontaneously applied amounts of liquid and ensure that the body fluids in the absorbent core are channeled to the superabsorber should guarantee.
  • the polymer in the swollen state must not form a barrier layer for the subsequent liquid. If the product has good transport properties, optimal utilization of the entire hygiene article can be guaranteed. The phenomenon of gel blocking is thus prevented, which in extreme cases leads to the leakage of the liquid, the so-called leakage of the hygiene article. So fluid transfer and distribution is critical in the initial absorption of body fluids.
  • Hydrogels for example, have good transport properties and, when swollen, have a high gel strength. Gels with only a low gel strength are deformable under an applied pressure (body pressure), clog pores in the superabsorbent / cellulose fiber absorbent body and thereby prevent further fluid absorption. Increased gel strength is generally achieved through higher crosslinking, which, however, reduces the retention of the product.
  • Surface post-crosslinking is an elegant method of increasing gel strength. In this process, dried superabsorbers with an average crosslinking density are subjected to additional crosslinking. The surface post-crosslinking increases the crosslinking density in the shell of the superabsorbent particles, which increases the absorption under pressure to a higher level is lifted.
  • the absorption capacity in the superabsorbent shell decreases, the core of the superabsorbent particles, due to the presence of movable polymer chains, has an improved absorption capacity compared to the shell, so that the shell structure ensures improved liquid transmission without the effect of gel blocking occurring. It is entirely desirable that the total capacity of the superabsorbent is not used spontaneously, but rather with a time delay. Since urine is usually applied to the hygiene article several times, the absorption capacity of the superabsorbent does not need to be exhausted after the first disposition.
  • Hydrophilic, highly swellable hydrogels are in particular polymers of (co) polymerized hydrophilic monomers, graft (co) polymers of one or more hydrophilic monomers on a suitable graft base, crosslinked cellulose or starch ethers, crosslinked carboxymethyl cellulose, partially crosslinked polyalkylene oxide or in aqueous Liquid-swellable natural products, such as guar derivatives.
  • Such hydrogels are used as products absorbing aqueous solutions for the production of diapers, tampons, sanitary napkins and other hygiene articles, but also as water-retaining agents in agricultural horticulture.
  • hydrophilic, highly swellable hydrogels are generally surface or gel post-crosslinked. This postcrosslinking is known per se to the person skilled in the art and is preferably carried out in the aqueous gel phase or as surface postcrosslinking of the ground and sieved polymer particles.
  • WO 93/21237 discloses (meth) acrylates of alkoxylated polyvalent C 2 -C 10 hydrocarbons as crosslinking agents. Trimethyl propane crosslinkers corresponding to SR 351, SR 454, SR 502, SR 9035 and SR 415 were used. These crosslinkers have 0, 3, 9, 15 or 20 EO units per TMP. According to WO 93/212373, 2 to 7 EO units per TMP, in particular 3 times 4 to 6 EO units per TMP, are advantageous.
  • a disadvantage of these compounds is that complex cleaning operations are required for at least partial separation of starting materials and by-products - the crosslinking agents used in the document mentioned have an acrylic acid content of less than 0.1% by weight.
  • EO-PO-EO block polymers are esterified with methacrylic acid.
  • DE 2215512 and DE 2215509 describe diacrylates of polyethylene glycol as crosslinking agents for copolymers for dicarboxylic acid anhydrides.
  • EP 559476 and US 4351922 describe diacrylates of polyethylene glycol and polyethylene-glycol-polypropylene glycol blocks as crosslinking agents for hydrogels.
  • No. 4,187,383 describes an esterification process of (meth) acrylic acid with organic polyols at a reaction temperature of 20 to 80 ° C. with an equivalent excess of 2 to 3: 1.
  • a disadvantage of this process is that the low reaction temperature means that the reaction times are up to 35 hours and the excess acid in the reaction mixture is removed by neutralization with subsequent phase separation.
  • a disadvantage of these processes is that it is limited to polyalkylene glycol monoalkyl ethers, that the catalyst has to be deactivated and that such copolymers cannot be used as crosslinking agents for hydrogels, since they only have one functionality.
  • the object was to provide further compounds which can be used as radical crosslinking agents for polymers, in particular for superabsorbers and to simplify the manufacturing process for substances that can be used as radical crosslinkers for superabsorbers. Furthermore, crosslinkers were sought whose hydrolysis stability is high and / or which at the same time result in a gel which can be very easily divided in the production process for superabsorbers.
  • p1 is 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, or 35,
  • p2 is 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20,
  • n 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21,
  • R1, R2 independently of one another H or CH3,
  • the AO units are installed in such a way that polyethers and no peroxides are formed.
  • Esters F with the above meaning are preferred, with all AOs R3 and R4 taking on the same meaning independently of one another, ie being accessible, for example, by alkoxylating ethylene glycol or polyethylene glycol with only one alkylene oxide, for example propylene oxide. Esters F with the above meanings are preferred, where R3 or R4 is H.
  • Esters F with the above meanings are preferred, where R3 or R4 independently of one another are CH3, CH2CH3, (CH2) 2-CH3 or (CH2) 7-CH3, preferably CH3.
  • esters F with the meaning given above, where p1 denotes 1, 2, 3, 4 or 5, particularly preferably 1, 2 or 3, in particular 1, or denotes a number between 14 and 27.
  • esters F with the above meaning, where p2 is 1, 2, 3, 4 or 5, particularly preferably 1, 2 or 3, in particular 1, or a number between 14 and 27.
  • Esters F with the above meanings are preferred, n being a number between 2 and 50, preferably between 5 and 30, in particular between 10 and 26.
  • esters F with the above meanings are preferred, the diol component (AO) p1 - [- O-CH2-CH2-] n-O- (AO) p2 having an average molecular weight between 300 and 500, in particular around 400.
  • esters F with the above meanings are preferred, the diol component (AO) p1 - [- O-CH2-CH2-] n-O- (AO) p2 having an average molecular weight of 2000 and 4000, particularly preferably between 2500 and 3500.
  • diol components in the case of ester F with the above meanings, which are structurally similar to one another with respect to (AO) p1 and (AO) p2.
  • Structurally similar is understood to mean that the respective (AO) p1 and (AO) p2 components are produced by simultaneous synthesis on the (poly) ethylene glycol, ie either either from mixtures of different alkoxides (statistical (AO) p components or are accessible from sequential synthesis (block (AO) p-components.)
  • those diol components are preferred in which all AOs have the same meaning and preferably arise from propylene oxide.
  • esters F with the above meanings are preferred, R1 and R2 being identical, preferably H.
  • the esters F of the abovementioned formula with the meanings given can be used for the preparation of hydrogel-forming polymers which absorb aqueous liquids, in particular as internal crosslinking agents.
  • Further preferred internal crosslinkers are di (meth) acrylates, in particular diacrylates of polypropylene glycol with 2, 3, 4 or 5, in particular 2 or 3, propylene glycol units.
  • Alkoxylated glycol is a compound of formula II
  • AO, R3, R4, p1, p2, n have the meaning given above or p1 is n is 0, p2 is 2, 3, 4 or 5, R3 is H and R4 is CH3.
  • the further object is achieved by a method for producing an ester F of alkoxylated glycol with (meth) acrylic acid, comprising the steps
  • (meth) acrylic acid is understood to mean methacrylic acid, acrylic acid or mixtures of methacrylic acid and acrylic acid. Acrylic acid is preferred.
  • ester F in pure form, it can be purified by known separation processes.
  • the molar excess of (meth) acrylic acid to alkoxylated glycol. is at least 2.1: 1, preferably at least 2.2: 1, particularly preferably at least 2.5: 1, very particularly preferably at least 3: 1 and in particular at least 5: 1.
  • (meth) acrylic acid is used in an excess of, for example, greater than 10: 1, preferably greater than 20: 1, particularly preferably greater than 40: 1, very particularly preferably greater than 100: 1, in particular greater than 150: 1 and especially used larger than 200: 1.
  • esterification products obtainable in this way can be used as radical crosslinkers in hydrogels essentially without further purification, especially without substantial removal of the excess of (meth) acrylic acid and the content of esterification catalyst C.
  • crosslinking in this document means radical crosslinking (gel crosslinking, internal crosslinking, crosslinking of linear or weakly crosslinked polymer).
  • This crosslinking can take place via free-radical or cationic polymerization mechanisms or other, for example Michael addition, transesterification or transesterification mechanisms, preferably by free-radical polymerization.
  • Hydrogel-forming polymers that absorb aqueous liquids are preferably those with an absorption of distilled water of at least their own weight, preferably 10 times their own weight, in particular 20 times their own weight; this absorption is preferably also carried out under a pressure of 0.7 psi reached.
  • alkoxylated glycols such as di- and tripropylene glycol or triblock polymers of PO-EO-PO type, such as the Pluronic ® RPE polymers used of the type 1720, 1 40, 2035, 2510, 2520, 2525 or 3110 become.
  • Esterification catalysts C which can be used according to the invention are sulfuric acid, aryl or alkylsulfonic acids or mixtures thereof.
  • arylsulfonic acids are benzenesulfonic acid, para-toluenesulfonic acid or dodecylbenzenesulfonic acid
  • alkylsulfonic acids are methanesulfonic acid, ethanesulfonic acid or trifluoromethanesulfonic acid.
  • Strongly acidic ion exchangers or zeolites can also be used as esterification catalysts. Sulfuric acid and ion exchangers are preferred.
  • Polymerization inhibitors D which can be used according to the invention are, for example, phenols such as alkylphenols, for example o-, m- or p-cresol (methylphenol), 2-tert-butyl-4-methylphenol, 6-tert.-butyl-2,4-dimethylphenol, 2,6-di-tert-butyl-4-methylphenol, 2-tert-butylphenol, 4-tert-butylphenol, 2,4-di-tert-butylphenol, 2-methyl-4-tert-butylphenol , 4-tert-butyl-2,6-dimethylphenol, or 2,2'-methylene-bis- (6-tert-butyl-4-methylphenol), 4,4'-oxydiphenyl, 3,4-methylenedioxydiphenol ( Sesamol), 3,4-dimethylphenol, hydroquinone, pyrocatechol (1,2-dihydroxybenzene), 2- (1 '-methylcyclohex-1'-yl) - 4,6-
  • hypophosphorous acid or triethyl phosphite sulfur-containing compounds such as diphenyl sulfide, phenothiazine or metal salts, such as copper, manganese, cerium, nickel, chromium, chloride, dithiocarbamate, sulfate, salicylate or acetate or Mixtures of these.
  • sulfur-containing compounds such as diphenyl sulfide, phenothiazine or metal salts, such as copper, manganese, cerium, nickel, chromium, chloride, dithiocarbamate, sulfate, salicylate or acetate or Mixtures of these.
  • the phenols and quinones mentioned are preferred; hydroquinone, hydroquinone monomethyl ether, 2-tert-butyl-4-methylphenol, 6-tert-butyl-2,4-dimethyl-phenol, 2,6-di-tert.- are particularly preferred.
  • Butyl-4-methylphenol, 2,4-di-tert-butylphenol, triphenylphosphite, hypophosphorous acid, CuCl 2 and guaiacol, hydroquinone and hydroquinone monomethyl ether are very particularly preferred.
  • ⁇ -Tocopherol (vitamin E), ⁇ -tocopherol, ⁇ -tocopherol, or ⁇ -tocopherol are very particularly preferred, optionally in combination with triphenyl phosphite and / or hypophosphorous acid
  • an oxygen-containing gas preferably air or a mixture of air and nitrogen (lean air) can be present.
  • stabilizers listed preferred are those that are aerobic, i.e. before they require the presence of oxygen to develop their full inhibitory effect.
  • Solvents E which can be used according to the invention are, in particular, those which are suitable for azeotropic removal of the water of reaction, if desired, in particular aliphatic, cycloaliphatic and aromatic hydrocarbons or mixtures thereof.
  • n-pentane, n-hexane, n-heptane, cyclohexane, methylcyclohexane, benzene, toluene or xylene are used.
  • Cyclohexane, methylcyclohexane and toluene are particularly preferred.
  • esterification the preparation and / or processing methods of polyhydric alcohols known to the person skilled in the art can be used, for example those mentioned at the beginning or those described in DE-A 199 41 136, DE-A 38 43 843, DE-A 38 43 854, DE- A 199 37 911, DE-A 199 29 258, EP-A 331 845, EP 554 651 or US 4 187 383.
  • esterification can be carried out as follows:
  • the esterification apparatus consists of a stirred reactor, preferably a reactor with a circulation evaporator and an attached distillation unit with a condenser and phase separation vessel.
  • the reactor can be, for example, a reactor with double-wall heating and / or internal heating coils.
  • a reactor with an external heat exchanger and natural or forced circulation i.e. using a pump, particularly preferably natural circulation, in which the circulation flow is accomplished without mechanical aids.
  • the reaction can of course also be carried out in a plurality of reaction zones, for example a reactor cascade composed of two to four, preferably two to three, reactors.
  • Suitable circulation evaporators are known to the person skilled in the art and are described, for example, in R. Billet, Verdampfertechnik, HTB-Verlag, bibliographisches Institut Mannheim, 1965, 53.
  • Examples of circulation evaporators are shell-and-tube heat exchangers, plate heat exchangers, etc.
  • the distillation unit is of a type known per se. This can be a simple distillation, which may be equipped with a splash guard, or a rectification column.
  • column internals for example trays, packings and / or fillings.
  • trays bubble trays, sieve trays, valve trays, Thormann trays and / or dual-flow trays are preferred, of the fillings those with rings, spirals, saddle bodies or braids are preferred.
  • the condenser and the separation vessel are of conventional construction.
  • esterification catalysts C are suitable. They are generally used in an amount of 0.1-5% by weight, based on the esterification mixture, preferably 0.5-5%, more preferably 1-4% and very particularly preferably 2-4% by weight.
  • the esterification catalyst can be removed from the reaction mixture using an ion exchanger.
  • the ion exchanger can be added directly to the reaction mixture and then filtered off, or the reaction mixture can be passed over an ion exchange bed.
  • the esterification catalyst is preferably left in the reaction mixture. However, if the catalyst is an ion exchanger, it is preferably removed, for example by filtration.
  • an oxygen-containing gas preferably air or a mixture of air and nitrogen (lean air) can be present.
  • This oxygen-containing gas is preferably metered into the bottom region of a column and / or into a circulation evaporator and / or passed through the reaction mixture and / or over it.
  • the polymerization inhibitor (mixture) D (as mentioned above) is used in a total amount of 0.01-1% by weight, based on the esterification mixture, preferably 0.02-0.8, particularly preferably 0.05-0. 5% by weight.
  • the polymerization inhibitor (mixture) D can be used, for example, as an aqueous solution or as a solution in a starting material or product.
  • the amount of solvent used is 10-200% by weight, preferably 20-100% by weight, particularly preferably 30-100% by weight, based on the sum of alkoxylated glycol and (meth) acrylic acid.
  • entrainer as described, for example, in DE-A1 3843 854, column 2, line 18 to column 4, line 45, but in contrast to this with the stabilizers mentioned above.
  • the water contained in the reaction mixture is not removed using an azeotroping solvent, it is possible to remove it by stripping with an inert gas, preferably an oxygen-containing gas, particularly preferably with air or lean air, for example as in DE-A 3843 843 described.
  • an inert gas preferably an oxygen-containing gas, particularly preferably with air or lean air, for example as in DE-A 3843 843 described.
  • the reaction temperature of the esterification a) is generally 40-160 ° C., preferably 60-140 ° C. and particularly preferably 80-120 ° C.
  • the temperature can remain the same or rise in the course of the reaction, but is preferably raised in the course of the reaction. In this case the final temperature of the esterification is 5 - 30 ° C higher than the initial temperature.
  • the temperature of the esterification can be determined and regulated by varying the solvent concentration in the reaction mixture, as described in DE-A 19941 136 and the German application with the file number 10063 175.4.
  • a solvent If a solvent is used, it can be distilled off from the reaction mixture via the distillation unit attached to the reactor.
  • the distillate can either be removed or, after condensation, fed into a phase separator.
  • the aqueous phase obtained in this way is generally discharged, the organic phase can be returned to the distillation unit and / or can be fed directly into the reaction zone and / or can be fed into a circulation evaporator, as in the German patent application with the file number 100 63 175.4.
  • the organic phase when used as reflux, the organic phase, as described in DE-A 19941 136, can be used to control the temperature in the esterification.
  • the esterification a) can be carried out without pressure, but also under overpressure or underpressure, preferably under normal pressure.
  • the reaction time is generally 2 to 20 hours, preferably 4 to 15 hours and particularly preferably 7 to 12 hours.
  • the order in which the individual reaction components are added is not essential according to the invention. All components can be initially mixed and then heated up, or one or more components cannot be initially or only partially and only added after the heating.
  • the composition of the (meth) acrylic acid which can be used is not restricted and can have, for example, the following components:
  • the crude (meth) acrylic acid used is generally stabilized with 200-600 ppm phenothiazine or other stabilizers in amounts which enable comparable stabilization.
  • carbonyl-containing includes acetone and lower aldehydes, e.g. Formaldehyde, acetaldehyde, crotonaldehyde, acrolein, 2- and 3-furfural and benzaldehyde, understood.
  • Crude (meth) acrylic acid is understood here to mean the (meth) acrylic acid-containing mixture which is obtained after absorption of the reaction gases from propane / propene / acrolein or isobutane / isobutene / methacrolein oxidation in an absorption medium and subsequent separation of the absorption medium or by fractionation Condensation of the reaction gases is obtained.
  • the pure (meth) acrylic acid used is generally stabilized with 100-300 ppm hydroquinone monomethyl ether or other storage stabilizers in amounts which enable comparable stabilization.
  • Pure or pre-cleaned (meth) acrylic acid is generally understood to mean (meth) acrylic acid, the purity of which is at least 99.5% by weight and which is essentially free of the aldehydic, other carbonyl-containing and high-boiling components.
  • the (meth) acrylic acid contained therein can advantageously be extracted with an extracting agent, preferably the solvent optionally used in the esterification, for example with cyclohexane, at a temperature between 10 and 40 ° C. and a ratio of aqueous phase to extracting agent of 1: 5. 30, preferably 1:10 - 20, extracted and returned to the esterification.
  • an inert gas preferably an oxygen-containing gas, particularly preferably air or a mixture of air and nitrogen (lean air) can be passed into the circulation, through or over the reaction mixture, for example in amounts of 0.1 1, preferably 0.2-0.8 and particularly preferably 0.3-0.7 m 3 / m 3 h, based on the volume of the reaction mixture.
  • the course of the esterification a) can be followed by tracking the amount of water discharged and / or the decrease in the carboxylic acid concentration in the reactor.
  • the reaction can be ended, for example, as soon as 90% of the theoretically expected amount of water has been discharged through the solvent, preferably at least 95% and particularly preferably at least 98%.
  • the end of the reaction can be determined, for example, by essentially no further water of reaction being removed via the entrainer. If (methacrylic) acid is discharged together with the water of reaction, its proportion can be determined, for example, by back-titrating an aliquot of the aqueous phase.
  • the (methacrylic) acid is used in a high stoichiometric excess, for example at least 3: 1, preferably at least 5: 1 and very particularly preferably at least 10: 1.
  • a substantial part of the amount of water formed remains in the reaction mixture.
  • the proportion of water which is determined by the volatility at the temperature applied is removed from the reaction mixture and, in addition, no measures are taken to separate off the water of reaction formed.
  • at least 10% by weight of the reaction water formed can remain in the reaction mixture, preferably at least 20% by weight, particularly preferably at least 30% by weight, very particularly preferably at least 40 and in particular at least 50% by weight.
  • the reactor mixture can be cooled in a customary manner to a temperature of from 10 to 30 ° C. and, if appropriate, by adding solvent, which can be the same as or different from the solvent which may be used for the azeotropic removal of water any target ester concentration can be set.
  • the reaction can be stopped with a suitable diluent G and to a concentration of, for example, 10-90% by weight, preferably 20-80%, particularly preferably 20 to 60%, very particularly preferably 30 to 50% and in particular diluted approx. 40%, for example to reduce the viscosity.
  • the diluent G is selected from the group consisting of water, a mixture of water with one or more water-soluble organic solvents or a mixture of water with one or more single or multi-functional alcohols, e.g. Methanol and glycerin.
  • the alcohols preferably carry 1, 2 or 3 hydroxyl groups and preferably have between 1 and 10, in particular up to 4, carbon atoms. Primary and secondary alcohols are preferred.
  • Preferred alcohols are methanol, ethanol, isopropanol, ethylene glycol, glycerin, 1,2-propanediol or 1,3-propanediol.
  • the reaction mixture can be decolorized, for example by treatment with activated carbon or metal oxides, such as, for example, aluminum oxide, silicon oxide, magnesium oxide, zirconium oxide, boron oxide or mixtures thereof, in amounts of, for example, 0.1-50% by weight 0.5 to 25% by weight, particularly preferably 1 to 10% by weight at temperatures of, for example, 10 to 100 ° C., preferably 20 to 80 ° C. and particularly preferably 30 to 60 ° C.
  • activated carbon or metal oxides such as, for example, aluminum oxide, silicon oxide, magnesium oxide, zirconium oxide, boron oxide or mixtures thereof, in amounts of, for example, 0.1-50% by weight 0.5 to 25% by weight, particularly preferably 1 to 10% by weight at temperatures of, for example, 10 to 100 ° C., preferably 20 to 80 ° C. and particularly preferably 30 to 60 ° C.
  • This can be done by adding the powdery or granular decolorizing agent to the reaction mixture and subsequent filtration or by passing the reaction mixture over a bed
  • the reaction mixture can be decolorized at any point in the workup process, for example at the stage of the crude reaction mixture or after prewashing, neutralization, washing or solvent removal, if appropriate.
  • the reaction mixture can further be subjected to a pre-wash e) and / or a neutralization f) and / or a post-wash g), preferably only a neutralization f). If necessary, neutralization f) and prewash e) can also be interchanged in the order.
  • the (meth) acrylic acid and / or catalyst C contained in the aqueous phase of the washes e) and g) and / or neutralization f) can be at least partially recovered by acidification and extraction with a solvent and used again.
  • the reaction mixture is washed in a washing apparatus with a washing liquid, for example water or a 5-30% by weight, preferably 5-20, particularly preferably 5-15% by weight Saline, potassium chloride, ammonium chloride, sodium sulfate or ammonium sulfate solution, preferably water or saline, treated.
  • a washing liquid for example water or a 5-30% by weight, preferably 5-20, particularly preferably 5-15% by weight Saline, potassium chloride, ammonium chloride, sodium sulfate or ammonium sulfate solution, preferably water or saline, treated.
  • the quantitative ratio of reaction mixture: washing liquid is generally 1: 0.1-1, preferably 1: 0.2-0.8, particularly preferably 1: 0.3-0.7.
  • the washing or neutralization can be carried out, for example, in a stirred tank or in other conventional equipment, e.g. in a column or mixer-settler apparatus.
  • the prewash e) is preferably used when metal salts, preferably copper or copper salts, are used as inhibitors (with).
  • Rinsing g) can be advantageous for removing base or salt traces from the reaction mixture neutralized in f).
  • the optionally prewashed reaction mixture which can still contain small amounts of catalyst and the main amount of excess (meth) acrylic acid, can be mixed with a 5-25, preferably 5-20, particularly preferably 5-15,% by weight aqueous solution Solution of a base, such as, for example, alkali or alkaline earth metal oxides, hydroxides, carbonates or hydrogen carbonates, preferably sodium hydroxide solution, potassium hydroxide solution, sodium hydrogen carbonate, sodium carbonate, potassium hydrogen carbonate, calcium hydroxide, lime milk, ammonia, ammonia water or potassium carbonate, which may be 5-15 %
  • a base such as, for example, alkali or alkaline earth metal oxides, hydroxides, carbonates or hydrogen carbonates, preferably sodium hydroxide solution, potassium hydroxide solution, sodium hydrogen carbonate, sodium carbonate, potassium hydrogen carbonate, calcium hydroxide, lime milk, ammonia, ammonia water or potassium carbonate, which may be 5-15 %
  • the degree of neutralization is preferably 5 to 60 mol%, preferably 10 to 40 mol%, particularly preferably 20 to 30 mol%, based on the monomers containing acid groups. This neutralization can take place before and / or during the polymerization, preferably before the polymerization. Another preferred degree of neutralization is 50 to 100 mol%, particularly preferably 55 to 80 mol%, in particular 60 to 75 mol%.
  • the crosslinking agent solution in pure acrylic acid is preferably only mixed with the acrylate solution to adjust the degree of neutralization shortly before the polymerization.
  • the base is added in such a way that the temperature in the apparatus does not rise above 60 ° C., is preferably between 20 and 35 ° C. and the pH is 4-13, preferably 4.5-10.
  • the heat of neutralization is preferably dissipated by cooling the container with the aid of internal cooling coils or via double-wall cooling.
  • the quantitative ratio of reaction mixture: neutralization liquid is generally 1: 0.1-1, preferably 1: 0.2-0.8, particularly preferably 1: 0.3-0.7.
  • a solvent is present in the reaction mixture, this can essentially be removed by distillation.
  • Optionally contained solvent is preferred after washing and / or neutralization from the reaction mixture removed, if desired, this can also be done before washing or neutralization.
  • an amount of storage stabilizer preferably hydroquinone monomethyl ether, is added to the reaction mixture such that 100-500, preferably 200-500 and particularly preferably 200-400 ppm thereof are present in the target ester (residue) after removal of the solvent.
  • hydroquinone monomethyl ether the sterically hindered phenols described above can also preferably be used alone or in a mixture with other stabilizers.
  • the main amount of solvent is removed by distillation, for example, in a stirred tank with double-wall heating and / or internal heating coils under reduced pressure, for example at 20-700 mbar, preferably 30-500 and particularly preferably 50-150 mbar and a temperature of 40-80 ° C. ,
  • the distillation can also be carried out in a falling film or thin film evaporator.
  • the reaction mixture is passed through the apparatus, preferably several times in a circuit, under reduced pressure, for example at 20-700 mbar, preferably 30-500 and particularly preferably 50-150 mbar and a temperature of 40-80 ° C.
  • An inert gas preferably an oxygen-containing gas, particularly preferably air or a mixture of air and nitrogen (lean air) can advantageously be introduced into the distillation apparatus, for example 0.1-1, preferably 0.2-0.8 and particularly preferably 0, 3 - 0.7 m 3 / m 3 h, based on the volume of the reaction mixture.
  • the residual solvent content in the residue after the distillation is generally below 5% by weight, preferably 0.5-5% and particularly preferably 1 to 3% by weight.
  • the separated solvent is condensed and preferably reused.
  • a solvent stripping i) can be carried out in addition to or instead of the distillation.
  • the target ester which still contains small amounts of solvent, is heated to 50-90 ° C., preferably 80-90 ° C., and the remaining amounts of solvent are removed with a suitable gas in a suitable apparatus.
  • a vacuum can also be applied to assist.
  • Suitable apparatuses are, for example, columns of a type which are known per se and which have the customary internals, for example trays, beds or oriented packings, preferably beds. In principle, all common conditions, such as floors, packings and / or fillers. Of the bottoms, bell bottoms, sieve bottoms, valve bottoms, Thormann bottoms and / or dual flow bottoms are preferred; of the fillings are those with rings, spirals, saddle bodies, Raschig, Intos or Pall rings, Barrel or Intalox saddles, Top-Pak etc. or braids, preferred.
  • a falling film, thin film or wiping film evaporator is also conceivable here, e.g. a Luwa, Rotafilm or Sambay evaporator, which can be equipped, for example, with a demister as a splash guard.
  • gases which are inert under the stripping conditions, preferably oxygen-containing gases, particularly preferably air or mixtures of air and nitrogen (lean air) or water vapor, in particular those which are heated to 50 to 100.degree.
  • the amount of stripping gas is, for example, 5-20, particularly preferably 10-20 and very particularly preferably 10 to 15 m 3 / m 3 h, based on the volume of the reaction mixture.
  • the ester can be subjected to filtration j) at any stage of the work-up process, preferably after washing / neutralization and, if appropriate, solvent removal, in order to remove traces of salts and any decolorizing agent present.
  • esterification a) of alkoxylated glycol with the (methacrylic) acid is carried out in a molar excess of at least 10: 1 as mentioned above in the presence of at least one esterification catalyst C and at least one polymerization inhibitor D without a solvent which forms an azeotrope with water ,
  • the (methacrylic) acid used in excess is essentially not separated, i.e. only the proportion of (methacrylic) acid which is determined by the volatility at the temperature applied is removed from the reaction mixture and, furthermore, no measures are carried out to separate the carboxylic acid, such as, for example, distillative, rectifying, extractive, such as Washes, absorptive, e.g. Transfer over activated carbon or over ion exchanger, and / or chemical steps, e.g. Trapping the carboxylic acid with epoxides.
  • the carboxylic acid such as, for example, distillative, rectifying, extractive, such as Washes, absorptive, e.g. Transfer over activated carbon or over ion exchanger, and / or chemical steps, e.g. Trapping the carboxylic acid with epoxides.
  • the (methacrylic) acid contained in the reaction mixture is preferably not more than 75% by weight, particularly preferably not more than 50% by weight, very particularly preferably not more than 25% by weight, in particular not more than 10% by weight and especially not more than 5% by weight separated from the reaction mixture to the (methacrylic) acid contained in the reaction mixture after the end of the reaction.
  • stage b) can be dispensed with, so that only the proportion of water of reaction and (methacrylic) acid which is determined by the volatility at the temperature applied is removed from the reaction mixture. This can preferably be prevented by essentially complete condensation.
  • esterification catalyst C used essentially remains in the reaction mixture.
  • the reaction mixture thus obtainable preferably has an acid number in accordance with. DIN EN 3682 of at least 25 mg KOH / g reaction mixture, more preferably at least 35 mg KOH / g, particularly preferably at least 45 mg KOH / g.
  • An acid number of 25 to 80 and very particularly preferably 35 to 50 mg KOH / g is particularly preferred as the range.
  • Prewashing or postwashing e) or g) is preferably dispensed with; only one filtration step j) can be useful.
  • reaction mixture can then be diluted in step c), in which case it is preferably converted to the hydrogel within 6 hours, particularly preferably within 3 hours. It can preferably be neutralized in step f).
  • the invention also relates to a mixture of substances
  • the mixture of substances can optionally be neutralized and have a pH, as listed above under f).
  • a pH as listed above under f.
  • the mixture of substances is neutralized, at least some of the (methacrylic) acid is converted into its water-soluble alkali metal, alkaline earth metal or ammonium salts.
  • Monomer M 0.5-99.9% by weight, particularly preferably 0.5-50% by weight, very particularly preferably 1-25, in particular 2-15 and especially 3 to 8, or 4 -5
  • Esterification catalyst C 0-10% by weight, particularly preferably 0.02-5%, very particularly preferably 0.05-2.5% by weight and in particular 0.1-1% by weight, polymerization inhibitor D 0-5% by weight .-%, particularly preferably 0.01-1.0, very particularly preferably 0.02-0.75, in particular 0.05-0.5 and especially 0.075-
  • Solvent E 0-10% by weight, particularly preferably 0-5% by weight, very particularly preferably 0.05-1.5% by weight and in particular 0.1-0.5% by weight, with the Provided that the sum is always 100 wt .-%, and - if necessary, diluent G ad 100 wt .-%.
  • reaction mixtures and mixtures according to the invention obtainable by the above process can be used
  • those mixtures of the invention are particularly suitable which have a water solubility (at 25 ° C. in distilled water) of at least 0.5% by weight, preferably at least 1% by weight, more preferably at least 2% by weight. -%, even more preferably at least 5% by weight, particularly preferably at least 10% by weight, very particularly preferably at least 20% by weight and in particular at least 30% by weight.
  • reaction mixture from the esterification including its work-up steps, as far as they are carried out, for example the reaction mixture from f), or, if f) is omitted, from b), or, if b) is dispensed with, the reaction mixture from a ), can optionally be combined with additional monoethylenically Saturated compounds N which do not carry acid groups but can be copolymerized with the hydrophilic monomers M can then be polymerized in the presence of at least one radical initiator K and optionally at least one graft base L to prepare water-absorbing hydrogels.
  • additional monoethylenically Saturated compounds N which do not carry acid groups but can be copolymerized with the hydrophilic monomers M can then be polymerized in the presence of at least one radical initiator K and optionally at least one graft base L to prepare water-absorbing hydrogels.
  • Hydrophilic monomers M suitable for producing k) these hydrophilic, highly swellable hydrogels are, for example, polymerizable acids, such as acrylic acid, methacrylic acid, ethacrylic acid, ⁇ -chloroacrylic acid, crotonic acid, maleic acid, maleic anhydride, vinylsulfonic acid, vinylphosphonic acid, maleic acid including its anhydride, fumaric acid, itaconic acid, citraconic acid, Mesaconic acid, glutaconic acid, aconitic acid, allylsulfonic acid, sulfoethyl acrylate, sulfomethacrylate, sulfopropyl acrylate, sulfopropyl methacrylate, 2-hydroxy-3-acryloxypropylsulfonic acid, 2-hydroxy-3-methacryloxypropylsulfonic acid, allylphosphonic acid, styrenesulfonic acid, 2-acrylamido-2-acrylamido-2
  • R 3 is hydrogen, methyl or ethyl
  • R 4 is the group -COOR 6 , a sulfonyl group or phosphonyl group, a phosphonyl group esterified with a (CrC 4 ) alkyl alcohol or a group of
  • R 5 is hydrogen, methyl, ethyl or a carboxyl group
  • R ⁇ 6 is hydrogen, amino or hydroxy (CC) alkyl and R 7 represents a sulfonyl group, a phosphonyl group or a carboxyl group.
  • Examples of (CC 4 ) alkyl alcohol are methanol, ethanol, n-propanol or n-butanol.
  • hydrophilic monomers are acrylic acid and methacrylic acid, especially acrylic acid.
  • additional monoethylenically unsaturated compounds N which do not carry any acid groups, but which can be copolymerized with the monomers bearing acid groups.
  • These include, for example, the amides and nitriles of monoethylenically unsaturated carboxylic acids, e.g. B. acrylamide, methacrylamide and N-vinylformamide, N-vinyl acetamide, N-methyl-vinyl acetamide, acrylonitrile and methacrylonitrile.
  • suitable compounds are, for example, vinyl esters of saturated C to C 4 carboxylic acids such as vinyl formate, vinyl acetate or vinyl propionate, alkyl vinyl ethers with at least 2 C atoms in the alkyl group, such as, for example, B. ethyl vinyl ether or butyl vinyl ether, esters of monoethylenically unsaturated C 3 - to C 6 -carboxylic acids, for. B. esters of monohydric C to C 18 alcohols and acrylic acid, methacrylic acid or maleic acid, half esters of maleic acid, eg. B.
  • vinyl esters of saturated C to C 4 carboxylic acids such as vinyl formate, vinyl acetate or vinyl propionate
  • alkyl vinyl ethers with at least 2 C atoms in the alkyl group such as, for example, B. ethyl vinyl ether or butyl vinyl ether, esters of monoethylenically unsaturated C 3 - to C 6 -car
  • N-vinyl lactams such as N-vinyl pyrrolidone or N-vinyl caprolactam
  • acrylic acid and methacrylic acid esters of alkoxylated monohydric saturated alcohols, e.g. B. of alcohols with 10 to 25 carbon atoms which have been reacted with 2 to 200 moles of ethylene oxide and / or propylene oxide per mole of alcohol
  • monoacrylic acid esters and monomethacrylic acid esters of polyethylene glycol or polypropylene glycol, the molar masses (M n ) the polyalkylene glycols can be, for example, up to 2000.
  • Other suitable monomers are styrene and alkyl-substituted styrenes such as ethylstyrene or tert-butylstyrene.
  • Hydroxyethyl acrylate in any ratio. These monomers which do not contain acid groups are added to the reaction mixture in amounts of between 0 and 50% by weight, preferably less than 20% by weight.
  • the crosslinked (co) polymers preferably consist of monoethylenically unsaturated monomers bearing acid groups, which are optionally converted into their alkali metal or ammonium salts before or after the polymerization, and from 0 to 40% by weight, based on their total weight, of no monoethylenically unsaturated monomers bearing acid groups.
  • Preferred hydrogels are those obtained by crosslinking polymerization or copolymerization of acid-bearing monoethylenically unsaturated monomers M or their salts.
  • the available polymers are characterized by an improved saponification index (VSI).
  • the starting polymer is treated with a postcrosslinker and preferably postcrosslinked and dried during or after the treatment by increasing the temperature, the crosslinker preferably being contained in an inert solvent.
  • Inert solvents are understood to mean those which in the reaction do not essentially react either with the starting polymer or with the postcrosslinker.
  • Preferred solvents are those which more than 90%, preferably more than 95%, particularly preferably more than 99%, in particular more than 99.5% do not react chemically with the starting polymer or postcrosslinker.
  • Preferred for post-crosslinking I) and drying m) is the temperature range between 30 and 250 ° C., in particular 50-200 ° C., and the range between 100-180 ° C. is very particularly preferred.
  • the surface postcrosslinking solution is preferably applied by spraying onto the polymer in suitable spray mixers. Following the spraying, the polymer powder is thermally dried, and the crosslinking reaction can take place both before and during the drying. It is preferred to spray on a solution of the crosslinking agent in reaction mixers or mixing and drying systems such as Lödige mixers, BEPEX mixers, NAUTA mixers, SHUGGI mixers or PROCESSALL. Fluid bed dryers can also be used.
  • Drying can take place in the mixer itself, by heating the jacket or by blowing in warm air.
  • a downstream dryer such as e.g. a rack dryer, a rotary kiln, or a heated screw. But it can also e.g. an azeotropic distillation can be used as the drying process.
  • the preferred residence time at this temperature in the reaction mixer or dryer is less than 60 minutes, particularly preferably less than 30 minutes.
  • the starting polymer being a polymeric acrylic acid or a polyacrylate, in particular a polymeric acrylic acid or a polyacrylate, which were obtained via free-radical polymerization and in which a polyfunctional ethylenically unsaturated radical crosslinker was used.
  • radical crosslinking agent is used in a dosage of 0.01-5.0% by weight, preferably 0.02-3.0% by weight, very particularly preferably 0.03-2.5% by weight. %, in particular 0.05-1.0 and especially 0.1 to 0.75% by weight, based on the starting polymer.
  • the invention also relates to polymers produced by one of the abovementioned processes and their use in hygiene articles, packaging materials and in nonwovens, and to the use of an abovementioned mixture of substances for the production of crosslinked or heat-crosslinkable polymers, in particular in paints and varnishes.
  • hydrophilic, highly swellable hydrogels (starting polymers) to be used are in particular polymers made from (co) polymerized hydrophilic monomers M, graft (co) polymers of one or more hydrophilic monomers M onto a suitable graft base L, crosslinked cellulose or starch ethers or swellable in aqueous liquids Natural products, such as guar derivatives.
  • starting polymers are in particular polymers made from (co) polymerized hydrophilic monomers M, graft (co) polymers of one or more hydrophilic monomers M onto a suitable graft base L, crosslinked cellulose or starch ethers or swellable in aqueous liquids Natural products, such as guar derivatives.
  • These hydrogels are known to the person skilled in the art and are described, for example, in US Pat. No.
  • Suitable graft bases L for hydrophilic hydrogels which can be obtained by graft copolymerization of olefinically unsaturated acids, can be of natural or synthetic origin. Examples are starch, cellulose or cellulose derivatives and other polysaccharides and oligosaccharides, polyalkylene oxides, in particular polyethylene oxides and polypropylene oxides, and hydrophilic polyesters.
  • the water-absorbing polymer can be obtained by radical graft copolymerization of acrylic acid or acrylate onto a water-soluble polymer matrix.
  • Suitable water-soluble polymer matrices include, but are not limited to, alginates, polyvinyl alcohol, and polysaccharides such as starch.
  • a polyfunctional ethylenically unsaturated radical crosslinker is used in the graft copolymerization in the sense of the invention.
  • the water-absorbing polymer can be an organic-inorganic hybrid polymer composed of a polymeric acrylic acid or a polyacrylate on the one hand and a silicate, aluminate or aluminosilicate on the other hand.
  • polymeric acrylic acid or polyacrylate can be used which have been obtained via free-radical polymerization and in which a polyfunctional ethylenically unsaturated radical crosslinking agent has been used and in the production process of which a water-soluble silicate or soluble aluminate or a mixture of both has been used.
  • Preferred hydrogels are, in particular, polyacrylates, polymethacrylates and the graft polymers described in US Pat. No. 4,931,497, US Pat. No. 5,011,892 and US Pat. No. 5,041,496.
  • Very particularly preferred hydrogels are the kneading polymers described in WO 01/38402 and the hybrid organic-inorganic hydrogels based on polyacrylates described in DE 19854575.
  • radical crosslinkers in hydrogels can be used alone or in combination with other crosslinkers, for example internal or surface crosslinkers, for example the following:
  • Suitable further crosslinkers are, in particular, methylenebisacryl or methacrylamide, esters of unsaturated mono- or polycarboxylic acids of polyols, such as diacrylate, triacrylate or tetraacrylate, e.g. B.
  • butanediol or ethylene glycol diacrylate or methacrylate and trimethylolpropane triacrylate or glycerol diacrylate and triacrylate or pentaerythritol tetraacrylate and allyl compounds such as allyl (meth) acrylate, triallylcyanoateurate, maleic acid diallyl ester, polyallylesylate ethyl, tetraallyl amyl acid, tetraallyl allyl ester, tetraallyl amyl ethane, tetraallyl allyl, tetraallyl allyl as described for example in EP-A-0 343427.
  • hydrogels which are prepared using polyethyl ether as further crosslinking agents and by acidic homopolymerization of acrylic acid.
  • Suitable crosslinkers are pentaerythritol tri- and tetraallyl ether, trimethylol propane diallyl ether, polyethylene glycol diallyl ether, monoethylene glycol diallyl ether, glycerol di and triallyl ether, polyallyl ether based on sorbitol, and ethoxylated variants thereof.
  • crosslinking agents are the polyethylene glycol diacrylates, ethoxylated derivatives of trimethylolpropane triacrylate, for example Sartomer SR 9035, and ethoxylated derivatives of glycerol diacrylate and glycerol triacrylate. Mixtures of the above crosslinking agents can of course also be used. Combinations of crosslinking agents in which further crosslinking agents F can be dispersed in the crosslinking agents F according to the invention are particularly preferred. Examples of such crosslinking combinations are the crosslinking agents F according to the invention together with di- or tripropylene glycol diacrylate and propoxylated glycerol triacrylates. Further examples of such crosslinker combinations are the crosslinking agents according to the invention together with butanediol diacrylate or trimethylolpropane triacrylate or pentaerythritol triallyl ether.
  • Hydrogels which are prepared as radical crosslinkers with an ester F prepared according to the invention are very particularly preferred.
  • the water-absorbing polymer is preferably a polymeric acrylic acid or a polyacrylate.
  • This water-absorbing polymer can be prepared by a process known from the literature. Polymers which contain crosslinking comonomers are preferred (0.001-10 mol%), but very particularly preferred are polymers which have been obtained by radical polymerization and in which a polyfunctional ethylenically unsaturated radical crosslinker has been used.
  • the hydrophilic, highly swellable hydrogels can be produced by polymerization processes known per se. Polymerization in aqueous solution by the so-called gel polymerization method is preferred. Dilute, preferably aqueous, particularly preferably 15 to 50% by weight aqueous solutions of one or more hydrophilic monomers and, if appropriate, a suitable graft base L in the presence of a radical initiator, preferably without mechanical mixing, using the Trommsdorff-Norrish Effect (Makromol. Chem. 1, 169 (1947)), polymerized. The polymerization reaction can be carried out in the temperature range between 0 ° C. and 150 ° C., preferably between 10 ° C.
  • the polymerization can also be carried out in a protective gas atmosphere, preferably under nitrogen.
  • a protective gas atmosphere preferably under nitrogen.
  • K can be used, e.g. B. organic peroxides such as benzoyl peroxide, tert-butyl hydroperoxide, methyl ethyl ketone peroxide, cumene hydroperoxide, azo compounds such as azodiisobutyronitrile and inorganic peroxy compounds such as (NH 4 ) 2S 2 O 8 , K 2 S 2 O ⁇ or H 2 O 2 .
  • reducing agents such as ascorbic acid, sodium bisulfite, and iron (II) sulfate or redox systems, which contain as a reducing component an aliphatic and aromatic sulfinic acid, such as benzenesulfinic acid and toluenesulfinic acid or derivatives of these acids, such as.
  • reducing agents such as ascorbic acid, sodium bisulfite, and iron (II) sulfate or redox systems, which contain as a reducing component an aliphatic and aromatic sulfinic acid, such as benzenesulfinic acid and toluenesulfinic acid or derivatives of these acids, such as.
  • B. Mannich adducts of sulfinic acids, aldehydes and amino compounds, as in the DE-C-1 301 566 are used.
  • the quality properties of the polymers can be improved further by reheating the polymer gels for several hours in the temperature range from 50 ° to 130
  • the gels obtained are neutralized to 0-100 mol%, preferably 25-100 mol%, and particularly preferably 50-85 mol%, based on the monomer used, it being possible to use the customary neutralizing agents, preferably alkali metal hydroxides, Alkali metal oxides or the corresponding alkali metal carbonates, but particularly preferably sodium hydroxide, sodium carbonate and sodium hydrogen carbonate.
  • the customary neutralizing agents preferably alkali metal hydroxides, Alkali metal oxides or the corresponding alkali metal carbonates, but particularly preferably sodium hydroxide, sodium carbonate and sodium hydrogen carbonate.
  • sodium hydroxide the quality obtainable by membrane electrolysis is particularly preferably used.
  • the neutralization is usually achieved by mixing in the neutralizing agent as an aqueous solution or preferably also as a solid.
  • the gel is mechanically crushed, e.g. using a meat grinder, and the neutralizing agent is sprayed, sprinkled or poured on, and then mixed thoroughly.
  • the gel mass obtained can be minced several times for homogenization.
  • the neutralized gel mass is then dried with a belt or roller dryer until the residual moisture content is preferably below 10% by weight, in particular below 5% by weight.
  • the polymerization itself can also be carried out by any of the other methods described in the literature.
  • the neutralization of the acrylic acid can also be carried out before the polymerization, as described in step f) above. Regardless of whether the neutralization takes place before, during or after the polymerization, it is particularly preferred to use acrylic acid with a dimer content below 2000 ppm, very particularly preferably below 1000 ppm, and most preferably below 500 ppm.
  • Sodium hydroxide from membrane electrolysis is very particularly preferably used. Compared to other processes, this is characterized by its high purity (e.g. low chloride content and absence of traces of mercury). Of course, sodium hydroxide from the amalgam or diaphragm process can also be used.
  • the polymerization can then be carried out continuously or batchwise in a belt reactor known to the person skilled in the art or in a kneading reactor. When the polymerization is carried out in a belt reactor, the initiation is electromagnetic
  • UV radiation preferably by means of UV radiation, or alternatively, particularly preferably initiation with a redox initiator system.
  • initiation methods are also very particularly preferred: electromagnetic radiation and chemical redox initiator system simultaneously.
  • the dried hydrogel can then be ground and sieved, with roller mills, pin mills or vibrating mills usually being used for grinding can be.
  • the preferred particle size of the sieved hydrogel is preferably in the range 45-1000 ⁇ m, preferably 45-850 ⁇ m, particularly preferably 200-850 ⁇ m, and very particularly preferably 300-850 ⁇ m.
  • Another particularly preferred range is 150-850 ⁇ m, in particular 150-700 ⁇ m, and particularly preferably 200-600 ⁇ m, and very particularly preferably 150-550 ⁇ m.
  • Another special range is 200 - 800 ⁇ m and a particularly preferred range is 250 - 650 ⁇ m, a very particularly preferred range is 300 - 600 ⁇ m.
  • ranges are 200-500 ⁇ m, 100-450 ⁇ m and 150-400 ⁇ m.
  • the following ranges are further preferred: 100 ⁇ m - 500 ⁇ m, 100 ⁇ m - 600 ⁇ m, 100 ⁇ m - 700 ⁇ m, 100 ⁇ m - 800 // m.
  • These areas preferably contain 80% by weight of the particles, in particular 90% by weight of the particles.
  • the size distribution can be determined using established screening methods or preferably also using optical methods (photographs).
  • the present invention furthermore relates to crosslinked hydrogels which contain at least one hydrophilic monomer M in copolymerized form and are crosslinked with an ester F of alkoxylated glycol with (methacrylic) acid.
  • the ester can be prepared according to the invention or in a manner known in the prior art, preferably in a manner according to the invention.
  • esters F Compounds as described above can be used as esters F.
  • the CRC value [g / g] of the hydrogel-forming polymers according to the invention can be measured by the methods given in the description and is preferably greater than 10, in particular 11, 12, 13, 14, 15, 16, 18, 20, 22, 24 or higher, particularly preferably 25, in particular 26, 27, 28, 29, particularly preferably 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45 or higher.
  • the AUL 0.7 psi value [g / g] of the hydrogel-forming polymers according to the invention can be measured by the methods given in the description and is preferably greater than 8, in particular 9, 10, 11, 12, 13, 14 or higher, particularly preferably at 15, in particular at 16, 17, 18, 19 or higher, particularly preferably greater than 20, in particular 21, 22, 23, 24, 25, 26, 27, 28 or higher.
  • the AUL-0.5psi value [g / g] of the hydrogel-forming polymers according to the invention can be measured by the methods given in the description and is preferably greater than 8, in particular 9, 10, 11, 12, 13, 14 or higher, particularly preferably at 15, in particular at 16, 17, 18, 19 or higher, particularly preferably greater than 20, in particular 21, 22, 23, 24, 25, 26, 27, 28 or higher.
  • the saponification index VSI of the hydrogel-forming polymers according to the invention can be measured according to the methods given in the description and is preferably less than 10, in particular 9.5, 9 or 8.5 or less, particularly preferably less than 8, in particular 7.5, 7, 6.5, 6, 5.5 or less, particularly preferably less than 5, in particular 4.5, 4, 3.5 or less.
  • the residual crosslinker content of the hydrogel-forming polymers according to the invention can be measured by the methods given in the description and is preferably less than 30 ppm, particularly preferably less than 20 ppm, very particularly preferably less than 10 ppm, in particular 9.5 ppm, 9 ppm or 8.5 ppm or less, particularly preferably less than 8 ppm, in particular 7.5 ppm, 7 ppm, 6.5 ppm, 6 ppm, 5.5 ppm or less, particularly preferably less than 5 ppm, in particular 4.5 ppm, 4 ppm, 3.5 ppm or less. If several crosslinkers are used in the mixture, these maximum values refer to each individual crosslinker in the mixture.
  • the present invention further relates to the use of the above-mentioned hydrogel-forming polymers in hygiene articles, comprising
  • (S) optionally a tissue layer located immediately above and below the core (R) and (T) optionally a receiving layer located between (P) and (R).
  • the percentages are to be understood such that at 10-100% by weight, 11, 12, 13, 14, 15, 16, 17, 18, 19 to 100% by weight of the hydrogel-forming polymer according to the invention and all those in between % Specifications (eg 12.2%) are possible and correspondingly hydrophilic fiber material from 0 to 89, 88, 87, 86, 85, 83, 82, 81% by weight and percentages in between (eg 87.8 %) possible are. If there are other materials in the core, the percentages of polymer and fiber decrease accordingly.
  • hydrogel-forming polymer according to the invention in the more preferred range 30, 31, 32, 33, 34, 35, 36, 37, 38, 39 to 100 wt .-% hydrogel-forming polymer according to the invention, in the even more preferred range 40, 41, 42, 43, 44, 45, 46, 47, 48, 49 to 100 wt % hydrogel-forming polymer according to the invention, in the more preferred range 50, 51, 52, 53, 54, 55, 56, 57, 58, 59 to 100% by weight hydrogel-forming polymer according to the invention, in the particularly preferred range 60, 61, 62, 63, 64, 65, 66, 67, 68, 69 to 100% by weight of hydrogel-forming polymer according to the invention, in the particularly preferred range 70, 71, 71, 72, 73, 74, 75, 76 , 77, 78, 79 to 100% by weight of hydrogel-forming polymer according to the
  • Hygiene articles mean incontinence pads and incontinence pants for adults as well as diapers for babies.
  • the liquid-permeable cover (P) is the layer that has direct skin contact.
  • the material for this consists of conventional synthetic or semi-synthetic fibers or films of polyester, polyolefins, rayon or natural fibers such as cotton. In the case of non-woven materials, the fibers are usually to be connected using binders such as polyacrylates. Preferred materials are polyester, rayon and their blends, polyethylene and polypropylene. Examples of liquid-permeable layers are described in WO 99/57355 A1, EP 102388 3 A2.
  • the liquid-impermeable layer (Q) usually consists of a film made of polyethylene or polypropylene. However, all other materials can be used that can be processed into liquid-impermeable films.
  • liquid impermeability means impermeability to condensed liquids.
  • the film can show permeability to the vapor of the liquid, and modern diaper designs often combine a high vapor permeability with maximum impermeability to the underlying condensed liquid which is usually water or urine.
  • the core (R) contains hydrophilic fiber material.
  • Hydrophilic is understood to mean that aqueous liquids are quickly distributed over the fiber.
  • the fiber material is cellulose, modified cellulose, rayon, polyester such as polyethylene terephthalate. Cellulose fibers such as cellulose are particularly preferred.
  • the fibers generally have a diameter of 1 to 200 ⁇ m, preferably 10 to 100 ⁇ m. In addition, the fibers have a minimum length of 1 mm.
  • the structure and shape of diapers is generally known and is described, for example, in WO 95/26 209 p. 66 line 34 to p. 69 line 11, DE 196 04 601 A1, EP-A-0 316 518 and EP-A-0 202 127.
  • diapers and other hygiene articles are also described in WO 00/65084, in particular on pages 6-15, WO 00/65348, in particular on pages 4 - 17, WO 00/35502, in particular pages 3-9, DE 19737434, WO 98 / 8439.
  • Hygiene articles for feminine hygiene are described in the following references.
  • the hydrogel-forming polymers absorbing aqueous liquids according to the invention can be used there.
  • Tampons are described in the following documents: WO 98/48753, WO 98/41179, WO 97/09022, WO 98/46182, WO 98/46181, WO 2001/043679, WO 2001/043680, WO 2000/061052, EP 1108408, WO 2001/033962, DE 200020662, WO 2001/001910, WO 2001/001908, WO 2001/001909, WO 2001/001906, WO 2001/001905, WO 2001/24729.
  • Incontinence articles are described in the following writings: Disposable Absorbent Articie for Incontinent Individuais: EP 311344 Description pp.
  • Disposable Absorbent Articie EP 850623; Absorbent Articie: WO 95/26207; Absorbent Articie: EP 894502; Dry Laid Fibrous Structure: EP 850 616; WO 98/22063; WO 97/49365; EP 903134; EP 887060; EP 887059; EP 887058; EP 887057; EP 887056; EP 931530; WO 99/25284; WO 98/48753.
  • Feminine hygiene and incontinence articles are described in the following documents: Catamenial Device: WO 93/22998 Description pp. 26 - 33; Absorbent Members for Body Fluids: WO 95/26209 description pp.
  • hydrogel-forming polymers according to the invention are outstandingly suitable as absorbents for water and aqueous liquids, so that they can advantageously be used as water-retaining agents in agricultural horticulture, as filtration aids and particularly as absorbent components in hygiene articles such as diapers, tampons or sanitary napkins.
  • the absorbent composition according to the present invention contains compositions which contain the highly swellable hydrogels or to which they are fixed. Any composition is suitable that can absorb the highly swellable hydrogels and that can also be integrated into the absorption layer. A large number of such compositions are already known and have been described in detail in the literature.
  • a composition for incorporating the highly swellable hydrogels can e.g. B. be a fiber matrix, which consists of a cellulose fiber mixture (airlaid web, wet laid web) or synthetic polymer fibers (meltblown web, spunbonded web), or consists of a mixed fiber structure made of cellulose fiber and synthetic fibers. Possible fiber materials are described in detail in the following chapter. The process of an air-laid web is described, for example, in WO 98/28 478. Furthermore, open-pore foams or the like can be used to incorporate highly swellable hydrogels.
  • such a composition can be created by fusing two individual layers, one or better a plurality of chambers being formed which contain the highly swellable hydrogels.
  • a chamber system is described in detail in EP 0 615 736 A1 p. 7 line 26 ff.
  • the two layers should be permeable to water.
  • the second layer can be either water permeable or water impermeable.
  • Tissues or other fabrics, closed or open-cell foams, perforated films, elastomers or fabrics made of fiber material can be used as layer material.
  • the absorbent composition consists of a composition of layers, the layer material should have a pore structure whose pore dimensions are small enough to retain the highly swellable hydrogel particles.
  • the above examples for the composition of the absorbent composition also include laminates of at least two layers, between which the highly swellable hydrogels are installed and fixed.
  • the absorbent composition can consist of a carrier material, such as. B. consist of a polymer film on which the highly swellable hydrogel particles are fixed. The fixation can be done on one or both sides.
  • the carrier material can be water-permeable or water-impermeable.
  • the highly swellable hydrogels are used in a weight fraction of 10 to 100% by weight, preferably 20-100% by weight, more preferably 30-100% by weight, even more preferably 40-100% by weight. %, more preferably 50-100% by weight, particularly preferably 60-100% by weight, particularly preferably 70-100% by weight, extremely preferably 80-100% by weight and most preferably 90-100% by weight. -% based on the total weight of the composition and the highly swellable hydrogels incorporated.
  • the structure of the present absorbent composition according to the invention is based on a variety of fiber materials which are used as fiber networks or matrices. Included in the present invention are both fibers of natural origin (modified or unmodified) and synthetic fibers.
  • Patent WO 95/26209 p. 28 line 9 to p. 36 line 8 gives a detailed overview of examples of fibers which can be used in the present invention. Said passage is therefore part of this invention.
  • cellulosic fibers include those commonly used in absorption products such as fleece pulp and cotton type pulp.
  • the materials coniferous or hardwoods
  • manufacturing processes such as chemical pulp, semi-chemical pulp, chemothermal mechanical pulp (CTMP) and
  • Bleaching processes are not particularly restricted.
  • natural Before application of cellulose fibers such as cotton, flax, silk, wool, jute, ethyl cellulose and cellulose acetate.
  • Suitable synthetic fibers are made from polyvinyl chloride, polyvinyl fluoride, polytetrafluoroethylene, polyvinylidene chloride, polyacrylics such as ORLON ®, polyvinyl acetate, polyethylvinyl acetate, polyvinyl alcohol soluble or insoluble.
  • synthetic fibers include thermoplastic polyolefin fibers such as polyethylene fibers (PULPEX ®), polypropylene fibers and polyethylene-polypropylene bicomponent fibers, polyester fibers such as polyethylene terephthalate fibers (DAC RON ® or KODEL ®), copolyesters, polyvinyl acetate, polyethylvinyl acetate, polyvinyl chloride, polyvinylidene chloride, polyacrylics , Polyamides, copolyamides, polystyrene and copolymers of the abovementioned polymers, and also two-component fibers made from polyethylene terephthalate-polyethylene-isophthalate copolymer, polyethylene vinyl acetate / polypropylene, polyethylene / polyester, polypropylene / polyester, copolyester / polyester, polyamide fibers ( Nylon), polyurethane fibers, polystyrene fibers and polyacrylonitrile fibers.
  • Polyolefin fibers, polyester fibers and their two-component fibers are preferred. Also preferred are heat-adhering two-component fibers made from shell-core type and side-by-side type made of polyolefin because of their excellent dimensional stability after liquid absorption.
  • thermoplastic fibers are preferably used in combination with thermoplastic fibers. During heat treatment, the latter partially migrate into the matrix of the existing fiber material and thus represent connection points and renewed stiffening elements when cooling.
  • thermoplastic fibers means an expansion of the existing pore dimensions after the heat treatment has taken place. In this way it is possible to continuously increase the proportion of thermoplastic fibers towards the cover sheet by continuously metering in thermoplastic fibers during the formation of the absorption layer, as a result of which an equally continuous increase in pore sizes results.
  • Thermoplastic fibers can be formed from a large number of thermoplastic polymers which have a melting point of less than 190 ° C., preferably between 75 ° C. and 175 ° C. At these temperatures, no damage to the cellulose fibers is yet to be expected.
  • the lengths and diameters of the synthetic fibers described above are not particularly limited, and in general, any fiber with a length of 1 to 200 mm and a diameter of 0.1 to 100 denier (grams per 9,000 meters) can be preferably used.
  • Preferred thermoplastic fibers have a length of 3 to 50 mm, particularly preferred a length of 6 to 12 mm.
  • the preferred diameter of the thermoplastic fiber is between 1, 4 and 10 decitex, particularly preferably between 1.7 and 3.3 decitex (grams per 10,000 meters).
  • the shape is not particularly limited, and examples include fabric-like ge, narrow cylinder-like, cut / splitting-like, staple fiber-like and endless fiber-like.
  • the fibers in the absorbent composition according to the invention can be hydrophilic, hydrophobic or a combination of both.
  • a fiber is said to be hydrophilic if the contact angle between the liquid and the fiber (or its surface) is less than 90 ° or if the liquid tends to spread spontaneously on the same surface. Both processes are usually non-existent.
  • a fiber is said to be hydrophobic if a contact angle of greater than 90 ° is formed and no spreading is observed.
  • Hydrophilic fiber material is preferably used. It is particularly preferred to use fiber material that is weakly hydrophilic on the body side and most hydrophilic in the region around the highly swellable hydrogels. In the manufacturing process, the use of layers of different hydrophilicity creates a gradient that channels the impinging liquid to the hydrogel, where absorption ultimately takes place.
  • Suitable hydrophilic fibers for use in the absorbent composition according to the invention are, for example, cellulose fibers, modified cellulose fibers, rayon, polyester fibers such as, for. B. polyethylene terephthalate (DACRON ® ), and hydrophilic nylon (HYDROFIL ® ).
  • Suitable hydrophilic fibers can also be obtained by hydrophilizing hydrophobic fibers, such as treating thermoplastic fibers obtained from polyolefins (such as polyethylene or polypropylene, polyamides, polystyrenes, polyurethanes, etc.) with surfactants or silica.
  • polyolefins such as polyethylene or polypropylene, polyamides, polystyrenes, polyurethanes, etc.
  • surfactants or silica are preferred for reasons of cost and availability.
  • the highly swellable hydrogel particles are embedded in the fiber material described. This can be done in a variety of ways, e.g. B. builds up an absorption layer in the form of a matrix with the hydrogel material and the fibers, or by embedding highly swellable hydrogels in layers of fiber mixture, where they are ultimately fixed, be it by adhesive or lamination of the layers.
  • the liquid-absorbing and -distributing fiber matrix can consist of synthetic fiber or cellulose fiber or a mixture of synthetic fiber and cellulose fiber, wherein the mixing ratio of (100 to 0) synthetic fiber: (0 to 100) cellulose fiber can vary.
  • the cellulose fibers used can additionally be chemically stiffened to increase the dimensional stability of the hygiene article.
  • the chemical stiffening of cellulose fibers can be achieved in different ways.
  • fiber stiffening can be achieved by adding suitable coatings to the fiber material. Include such additions examples play as polyamide-epichlorohydrin coatings (Kymene ® 557H, Hercules, Inc. Wil- Remington Delaware, USA), polyacrylamide coatings (described in US Patent No. 3,556,932 or as a product of Parez ® 631 NC trademark, American Cyanamid Co., Stamford, CT, USA), melamine-formaldehyde coatings and polyethyleneimine coatings.
  • Suitable crosslinking substances are typical substances that are used to crosslink monomers. Included, but not limited to, are C 2 -C 8 dialdehydes, C 2 -C 8 mono-aldehydes with acid functionality, and in particular C 2 -C 9 polycarboxylic acids. Specific substances from this series are, for example, glutaraldehyde, glyoxal, glyoxylic acid, formaldehyde and citric acid.
  • Chemically crosslinked cellulose fibers are known and are described in WO 91/11162, U.S. Patent 3,224,926, U.S. Patent 3,440,135, U.S. U.S. Patent 3,932,209 Patent 4,035,147, U.S. U.S. Patent 4,822,453, U.S. U.S. Patent 4,888,093, U.S. U.S. Patent 4,898,642 and U.S. Patent 5,137,537.
  • the chemical crosslinking stiffens the fiber material, which is ultimately reflected in the improved dimensional stability of the entire hygiene article.
  • the individual layers are by methods known to those skilled in the art, such as. B. fused together by heat treatment, adding hot melt adhesives, latex binders, etc.
  • the absorbent composition is composed of compositions which contain highly swellable hydrogels and the highly swellable hydrogels which are present in the compositions or are fixed thereto.
  • Examples of processes with which an absorbent composition is obtained which, for example, consist of a carrier material to which hydrogels which are highly swellable on one or both sides are fixed, are known and included, but not limited to, by the invention.
  • Examples of processes with which an absorbent composition is obtained which consists, for example, of highly swellable hydrogels (c) embedded in a fiber material mixture of synthetic fibers (a) and cellulose fibers (b), the mixing ratio of (100 to 0) synthetic fibers : (0 to 100) cellulose fiber may vary include (1) a process in which (a), (b) and (c) are mixed simultaneously, (2) a process in which a mixture of (a) and ( b) is mixed into (c), (3) a process in which a mixture of (b) and (c) is mixed with (a), (4) a process in which a mixture of (a) and ( c) is mixed into (b), (5) a process in which (b) and (c) are mixed and (a) is metered in continuously, (6) a process in which (a) and (c) are mixed and (b) is metered in continuously, and (7) a process in which (b) and (c) are mixed separately into (a).
  • methods (1) and (5) are preferred.
  • the correspondingly produced absorbent composition can optionally be subjected to a heat treatment, so that an absorption layer with excellent dimensional stability in the moist state results.
  • the heat treatment method is not particularly limited. Examples include heat treatment by supplying hot air or infrared radiation.
  • the temperature during the heat treatment is in the range from 60 ° C. to 230 ° C., preferably between 100 ° C. and 200 ° C., particularly preferably between 100 ° C. and 180 ° C.
  • the duration of the heat treatment depends on the type of synthetic fiber, its quantity and the speed of manufacture of the hygiene article. In general, the duration of the heat treatment is between 0.5 seconds to 3 minutes, preferably 1 second to 1 minute.
  • the absorbent composition is generally provided, for example, with a liquid pervious top layer and a liquid impervious bottom layer. Leg cuffs and adhesive tapes are also attached, thus completing the hygiene article.
  • the materials and types of the permeable cover layer and impermeable underlayer, as well as the leg ends and adhesive tapes are known to the person skilled in the art and are not particularly restricted. Examples of this can be found in WO 95/26 209.
  • the advantage of the present invention resides in the fact that the esters F which can be used as crosslinkers do not have to be purified after they have been prepared, in particular that the (meth) acrylic acid, preferably acrylic acid, does not have to be separated off since these are generally a monomer for the preparation of the hydrogels represents.
  • ppm and percentages used in this document relate to percentages by weight and ppm.
  • the superabsorbent crosslinkers are prepared by esterifying alkoxylated glycol with acrylic acid, the water being separated off in an azeotropic distillation.
  • Esterification catalyst is sulfuric acid in the examples.
  • the reactants are presented together with a stabilizer mixture consisting of hydroquinone monomethyl ether, triphenyl phosphite and hypophosphorous acid in the examples in methylcyclohexane as an entrainer.
  • the reaction mixture is then heated to approximately 98 ° C. until the azeotropic distillation begins. During the azeotropic distillation, the temperature in the reaction mixture rises. The amount of water separated off is determined. The distillation is stopped when at least the theoretical amount of water has been removed.
  • the entrainer is then removed in a vacuum distillation.
  • the product is cooled and used as a crosslinker in the production of superabsorbents.
  • Tripropylene glycol is a commercially available diol component.
  • 506 parts of the propoxylated polyglycol (according to Example 1b) are esterified with 200 parts of acrylic acid and 5 parts of sulfuric acid in 345 parts of methylcyclohexane.
  • 2 parts of hydroquinone monomethyl ether, 2 parts of ⁇ -tocopherol and 1 part of hypophosphorous acid are added as auxiliaries.
  • 36 parts of water are separated off before the entrainer is removed by vacuum distillation.
  • the product is cleaned using K300 filters.
  • the acid number is determined.
  • acrylic acid By adding 40 parts of acrylic acid, the viscosity of the slightly colored product (APHA ⁇ 100) is further reduced.
  • Tripropylene glycol diacrylate is commercially available as Laromer TPGDA (BASF AG). However, it can also be produced completely analogously to the above examples.
  • test methods To determine the quality of the surface crosslinking, the dried hydrogel can be examined using the following test methods. test methods
  • This method determines the free swellability of the hydrogel in the tea bag.
  • 0.2000 +/- 0.0050 g of dried hydrogel (grain fraction 106 - 850 ⁇ m) are weighed into a 60 x 85 mm tea bag, which is then sealed.
  • the tea bag is placed in an excess of 0.9% by weight saline solution (at least 0.83 l saline solution / 1 g polymer powder) for 30 minutes.
  • the tea bag is then centrifuged at 250 g for 3 minutes. The amount of liquid is determined by weighing the centrifuged tea bag.
  • the measuring cell for determining the AUL 0.7 psi is a plexiglass cylinder with an inner diameter of 60 mm and a height of 50 mm, which has a glued-on stainless steel sieve bottom with a mesh size of 36 ⁇ m on the underside.
  • the measuring cell also includes a plastic plate with a diameter of 59 mm and a weight, which can be placed together with the plastic plate in the measuring cell.
  • the weight of the plastic plate and the total weight are 1345 g.
  • the weight of the empty plexiglass cylinder and the plastic plate is determined and noted as W 0 .
  • a ceramic filter plate with a diameter of 120 mm, a height of 10 mm and a porosity 0 Duran, Schott
  • a round filter paper with a diameter of 90 mm and a pore size ⁇ 20 ⁇ m (S&S 589 black tape from Schleicher & Schüll) is placed on the ceramic plate.
  • the plexiglass cylinder containing the hydrogel-forming polymer is now placed with the plastic plate and weight on the filter paper and left there for 60 minutes.
  • AUL absorption under pressure
  • the AUL 0.5psi is measured analogously with lower pressure.
  • this residual crosslinking agent is first extracted from the dried hydrogel by means of a double extraction. Weigh 0.400 g of dry hydrogel and 40 g of 0.9% by weight saline solution into a closable and centrifugable ampoule. To do this, add 8 ml of dichloromethane, close the ampoule and then shake for 60 minutes. The ampoule is then immediately centrifuged at 1500 rpm for 5 minutes, so that the organic phase is clearly separated from the aqueous phase.
  • the sample obtained in this way is separated by means of liquid phase chromatography and analyzed by mass spectrometry.
  • the quantification is carried out against a dilution series of the same crosslinking agent used.
  • a Zorbax Eclipse XDB C-8 (150 x 4.6 mm - 5 ⁇ m) is used as the chromatography column and a Zorbax Eclipse XDB C-8 (12.5 x 4.6 mm - 5 ⁇ m) as the precolumn.
  • a methanol / water mixture (75/25) is used as the eluent.
  • the gradient course is as follows:
  • Flow is 1 ml / min at 1600 psi pressure.
  • the injection volume is 20 ⁇ l.
  • Typical analysis time is 5 - 30 min for the samples.
  • the detection is done by mass spectrometry e.g. in the range 800 - 1300 m / z (fill scan, positive).
  • the device works with APCI (Atmospheric Pressure Chemical Ionization, positive ionization).
  • APCI atmospheric Pressure Chemical Ionization, positive ionization
  • the capillary temperature is set to 180 ° C
  • the APCI vaporizer temperature to 450 ° C
  • source current to 5.0 ⁇ A
  • the gas flow 80 ml / min.
  • the individual settings must be made specifically for each networker.
  • the characteristic peaks that are later relevant for the evaluation are determined using a suitable calibration solution of the crosslinking agent.
  • the main peak is usually selected.
  • CONCprobe A Probe x CONCstd x VF / As td
  • CONCprobe is the desired crosslinker concentration in the dry hydrogel in mg / kg
  • CONCstd is the desired crosslinker concentration in the calibration solution in mg / kg
  • Ap r obe is the peak area of the extract sample of the dried hydrogel
  • VF is the dilution factor
  • M DC M is a weight of dichloromethane for extraction
  • M r0be is a sample of dry hydrogel
  • Ms o iv is a weight of methanol-water mixture + monoethylene glycol
  • M E ⁇ t r a c t is a weight of dichloromethane extract
  • the crushed gel is then treated in two different ways:
  • the comminuted gel is homogeneously distributed in a thin layer on sheets with sieve trays and then dried in vacuo at 80 ° C. for 24 h. This drying is very gentle on the product and is therefore the optimal standard of comparison.
  • the dried hydrogel is then ground and the 300-600 micron sieve fraction is isolated.
  • the crushed gel is first annealed in a sealed plastic bag at 90 ° C for 24 h. Then it is distributed homogeneously in a thin layer on sheets with sieve trays and dried in vacuo at 80 ° C. for 24 h. This drying simulates the drying conditions that occur in typical production plants, which usually limit the drying performance and throughput due to the associated decrease in quality.
  • the dried hydrogel is ground and the sieve fraction of 300-600 micrometers is isolated.
  • the hydrogels obtained by the two work-up methods are characterized by determining the teabag capacity (CRC) and the content of extractables after 16 h and with regard to the content of unreacted residual crosslinking agent.
  • CRC teabag capacity
  • the moisture content is determined and if this is more than 1% by weight, it is taken into account in the calculation of these properties.
  • the moisture content is typically about 5% by weight.
  • the saponification index (VSI) of the crosslinking agent in the gel is then determined from the measured values, which is calculated as follows:
  • the subscripts here indicate the processing method 1 or 2.
  • the saponification index is therefore greater, the more the tea bag capacity increases due to the drying process and the more the extractables increase. Both contributions are weighted equally.
  • crosslinkers whose saponification index is as small as possible.
  • the ideal networker has a VSI of zero.
  • the use of such crosslinkers enables the performance of the industrial dryer to be increased to the technically achievable maximum without sacrificing quality.
  • the reason for this is that the crosslinking set during the polymerization - and thus the properties of the end product - no longer change due to hydrolysis during drying.
  • Example 3 Preparation of superabsorbent using the acrylic acid ester from Example 2 and other internal crosslinkers
  • V-50 (2,2'-azobisamidinopropane dihydrochloride) and 3.05 g sodium persulfate were added as initiators.
  • the initiators are advantageously pre-dissolved in part of the preparation water. The mixture is stirred well for a few minutes.
  • the gel block is first broken into pieces and then crushed by a meat grinder with a 6 mm perforated disc.
  • the crushed gel is then treated in two different ways:
  • the comminuted gel is homogeneously distributed in a thin layer on sheets with sieve trays and then dried in vacuo at 80 ° C. for 24 h. This drying is very gentle on the product and is therefore the optimal standard of comparison.
  • the dried hydrogel is then ground and the 300-600 micron sieve fraction is isolated.
  • the crushed gel is first annealed in a sealed plastic bag at 90 ° C for 24 h. Then it is distributed homogeneously in a thin layer on sheets with sieve trays and dried in vacuo at 80 ° C. for 24 h. This drying simulates the drying conditions that occur in typical production plants, which usually limit the drying performance and throughput due to the associated decrease in quality.
  • the dried hydrogel is ground and the sieve fraction of 300-600 micrometers is isolated.
  • the gel obtained after the polymerization is dried, ground and crushed according to processing method 1.
  • the dry normal base polymer powder is mixed with a solution of 0.12% by weight of N-hydroxyethyl-2-oxazolidinone, 3.35% by weight of water and 1.65% by weight of 1,2-propanediol, based in each case on Polymer - sprayed homogeneously with stirring.
  • the batch size is 1.2 kg
  • spraying is carried out by means of a two-component nozzle by atomizing the solution with nitrogen.
  • a ploughshare mixer from Lödige with a working volume of 5 l is used.
  • the moist powder is then heated in a drying cabinet at 180 ° C. for 60 min. Then sieve again at 850 micrometers to remove agglomerates.

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Abstract

L'invention concerne de nouveaux esters (méth)acryliques de glycols polyalkoxylés de formule (I), dans laquelle AO signifie pour chaque AO indépendamment l'un de l'autre -0-CHR3- CHR4- ou -CHR3-CHR4-0-, R3 et R4 représentent indépendamment l'un de l'autre H, alkyle C1 -C8 linéaire ou ramifié, p1 désigne 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34 ou 35, p2 signifie 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34 ou 35, n représente 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 447, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 80, 81, 82, 83, 84, 85, 86, 87, 88, 89, 90, 91, 92, 93, 94, 95, 96, 97, 98, 99, 100, R1, R2 désignent indépendamment l'un de l'autre H ou CH3, R3 et R4 ne désignant pas simultanément H au moins pour un AO en (AO)p1 et au moins pour un AO en (AO)p2. La présente invention porte également sur un procédé simplifié pour réaliser ces esters et sur l'utilisation des mélanges réactionnels ainsi obtenus.
EP04736051A 2003-06-06 2004-06-04 Esters (meth)acryliques de glycols alkylene-ylene et leur utilisation Withdrawn EP1636291A1 (fr)

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PCT/EP2003/005953 WO2003104300A1 (fr) 2002-06-01 2003-06-06 Esters (meth)acryliques de trimethylolpropane polyalcoxyle
DE2003158369 DE10358369A1 (de) 2003-06-06 2003-12-11 (Meth)acrylester von Alkylenylenglycolen und deren Verwendung
PCT/EP2004/006033 WO2004108795A1 (fr) 2003-06-06 2004-06-04 Esters (meth)acryliques de glycols alkylene-ylene et leur utilisation

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CA2527362A1 (fr) 2004-12-16
JP2006527179A (ja) 2006-11-30
WO2004108795A1 (fr) 2004-12-16
MXPA05012802A (es) 2006-02-22
BRPI0410899A (pt) 2006-07-04

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