Classifications

• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
  • C08J9/00—Working-up of macromolecular substances to porous or cellular articles or materials; After-treatment thereof
  • C08J9/04—Working-up of macromolecular substances to porous or cellular articles or materials; After-treatment thereof using blowing gases generated by a previously added blowing agent
  • C08J9/12—Working-up of macromolecular substances to porous or cellular articles or materials; After-treatment thereof using blowing gases generated by a previously added blowing agent by a physical blowing agent
  • C08J9/14—Working-up of macromolecular substances to porous or cellular articles or materials; After-treatment thereof using blowing gases generated by a previously added blowing agent by a physical blowing agent organic
  • C08J9/141—Hydrocarbons
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61L—METHODS OR APPARATUS FOR STERILISING MATERIALS OR OBJECTS IN GENERAL; DISINFECTION, STERILISATION OR DEODORISATION OF AIR; CHEMICAL ASPECTS OF BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES; MATERIALS FOR BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES
  • A61L15/00—Chemical aspects of, or use of materials for, bandages, dressings or absorbent pads
  • A61L15/16—Bandages, dressings or absorbent pads for physiological fluids such as urine or blood, e.g. sanitary towels, tampons
  • A61L15/22—Bandages, dressings or absorbent pads for physiological fluids such as urine or blood, e.g. sanitary towels, tampons containing macromolecular materials
  • A61L15/26—Macromolecular compounds obtained otherwise than by reactions only involving carbon-to-carbon unsaturated bonds; Derivatives thereof
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61L—METHODS OR APPARATUS FOR STERILISING MATERIALS OR OBJECTS IN GENERAL; DISINFECTION, STERILISATION OR DEODORISATION OF AIR; CHEMICAL ASPECTS OF BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES; MATERIALS FOR BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES
  • A61L15/00—Chemical aspects of, or use of materials for, bandages, dressings or absorbent pads
  • A61L15/16—Bandages, dressings or absorbent pads for physiological fluids such as urine or blood, e.g. sanitary towels, tampons
  • A61L15/42—Use of materials characterised by their function or physical properties
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61L—METHODS OR APPARATUS FOR STERILISING MATERIALS OR OBJECTS IN GENERAL; DISINFECTION, STERILISATION OR DEODORISATION OF AIR; CHEMICAL ASPECTS OF BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES; MATERIALS FOR BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES
  • A61L15/00—Chemical aspects of, or use of materials for, bandages, dressings or absorbent pads
  • A61L15/16—Bandages, dressings or absorbent pads for physiological fluids such as urine or blood, e.g. sanitary towels, tampons
  • A61L15/42—Use of materials characterised by their function or physical properties
  • A61L15/425—Porous materials, e.g. foams or sponges
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
  • C08J9/00—Working-up of macromolecular substances to porous or cellular articles or materials; After-treatment thereof
  • C08J9/36—After-treatment
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
  • C08J2205/00—Foams characterised by their properties
  • C08J2205/04—Foams characterised by their properties characterised by the foam pores
  • C08J2205/05—Open cells, i.e. more than 50% of the pores are open
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
  • C08J2205/00—Foams characterised by their properties
  • C08J2205/06—Flexible foams
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
  • C08J2361/00—Characterised by the use of condensation polymers of aldehydes or ketones; Derivatives of such polymers
  • C08J2361/20—Condensation polymers of aldehydes or ketones with only compounds containing hydrogen attached to nitrogen
  • C08J2361/26—Condensation polymers of aldehydes or ketones with only compounds containing hydrogen attached to nitrogen of aldehydes with heterocyclic compounds
  • C08J2361/28—Condensation polymers of aldehydes or ketones with only compounds containing hydrogen attached to nitrogen of aldehydes with heterocyclic compounds with melamine

Definitions

• the invention relates to hydrophilic, open-cell, elastic foams based on melamine / formaldehyde resins, their manufacture and their use in hygiene articles.
• EP-A-0 017 621 and EP-A-0 017 672 disclose open-cell, elastic foams based on melamine / formaldehyde condensation products and processes for their production.
• the process known from EP-A-0 037 470 is used to produce open-cell, elastic foams from melamine / formaldehyde condensation products particularly advantageously by the action of microwave energy (ultra-high frequency radiation) on an aqueous solution or dispersion, each of which is a Contain melamine / formaldehyde precondensate, an emulsifier, a blowing agent and a hardener.
• the solution or dispersion is heated in such a way that it foams and the precondensate hardens.
• the foams obtainable in this way emit small amounts of formaldehyde, the formaldehyde emission increasing with increasing temperature and moisture of the foam.
• the foams made from melamine / formaldehyde resins ' are indeed highly hydrophilic, ' but have a relatively high release of formaldehyde when they come into contact with body fluids. This considerably limits the possible uses of such foams in hygiene articles.
• the older, not prepublished DE application No. 100 27 770.5 describes the production of foams from low-formaldehyde, open-cell melamine / formaldehyde resins with a molar ratio of melamine / formaldehyde of 1: 1.0 to 1: 1, 9 described.
• These foams emit less than 30 mg formaldehyde / kg foam even under the usual warm / humid conditions in the hygiene sector (EU standard EN ISO 14 184-1, water storage for 1 hour at 40 degrees C). They thus meet the requirements of the ⁇ KOTEX Standard 100 (quality seal of the textile industry for particularly low-pollution textiles) made of baby clothing.
• the significant reduction in formaldehyde emissions is achieved with a bought partial loss of the hydrophilic properties of the foam, whereby the liquid absorption rate of such foam layers decreases.
• WO-A-96/21682 discloses foams which, owing to their open-cell structure, are outstandingly suitable for the absorption of aqueous body fluids, in particular for blood absorption.
• the foams are obtained by polymerizing (C 4 -C 14 ) alkyl acrylates, (C 6 -C 16 alkyl methacrylates, (C 4 -C 12 ) alkyl styrenes as monomers, preferably styrene and ethyl styrene as comonomers, des further aromatic polyvinyl compounds as crosslinking agents, optionally polyfunctional acrylates, methacrylates, acrylamides and methacrylamides and mixtures thereof as additional crosslinking agents
• HIPE high internal phase emulsion
• WO-A-97/07832 US-A-5, 318, 554 and US-A-5, 550, 167 relate to the production of open-cell foams based on HIPE emulsions and their use for the absorption of aqueous body fluids.
• the open-cell foams are always used together with other components that take over the final absorption (immobilization) of body fluids in the hygiene article.
• these materials have good application properties, they nevertheless have clear disadvantages.
• Their manufacture is extremely complex because the process is difficult to control from a process engineering point of view.
• the enormous amount of aqueous phase (aqueous salt solution) is neither economically nor ecologically sensible.
• the materials also have a salt layer on the surface for hydrophilization.
• This layer can be removed during use and washed out into the storage medium of the absorbent core.
• Superabsorbers are generally used as the storage medium.
• Superabsorbents are known to exhibit the phenomenon of "salt poisoning", i.e. their absorption capacity drops dramatically with increasing salt content of the solution to be absorbed. It is therefore disadvantageous to additionally increase the salt load in the body fluids to be absorbed.
• the object is achieved according to the invention with hydrophilic, open-cell, elastic foams made from melamine / formaldehyde resins, which have a drop absorption rate of less than 5 seconds and whose formaldehyde emissions according to the EU standard EN 5 ISO 14184-1 are less than 100 mg formaldehyde / kg Exhibition material.
• Such foams have, for example, a density of 5 to 200 g / l, a specific surface area (determined according to BET) of more than 10 m 2 / g and a free swell capacity of more than 20 g / g. You assign e.g. a tensile strength of> 60 J / m2 when wet.
• the invention also relates to a method for producing hydrophilic, open-cell, elastic foams, 15 wherein one
• Process step (a) is known from the prior art, cf. the literature references EP-A-0 017 already dealt with above
• the molar ratio of melamine to formaldehyde is, for example, 1: 1.0 to 1: 5 and is preferably in the range from 1: 1.0 up to 1: 1.9.
• the preferred range is known from the older, not prepublished DE application No. 100 27 770.5. Particularly beneficial for
• the production of low-formaldehyde melamine / formaldehyde resins is a molar ratio of melamine to formaldehyde of 1: 1.3 to 1: 1.8.
• Foaming according to process step (a) takes place by heating the mixture to a temperature above the boiling point of the blowing agent and is carried out, for example,
• the foaming of the aqueous mixture of melamine / formaldehyde precondensate, emulsified gator, blowing agent and hardener is preferably done by the action of microwave energy according to the method known from EP-A-0 0 37 470.
• Bulk density according to DIN 53 420 is between 1.6 and 30, preferably between 2 and 20 [g / 1]
• Compression hardness according to DIN 53 577 at 60% compression, divided by the bulk density is less than 0.3, preferably less than 0.2 [N. cm _2 / g. I " 1 ], wherein when determining the compression hardness at 60% compression, the foam must be recuperated to 70%, preferably at least 90% and in particular 95% of its original dimensions.
• Elastic modulus based on DIN 53 423 divided by the bulk density is below 0.25, preferably below 0.15 [N.mm- 2 / gl- 1 ].
• Dynamic stiffness according to DIN 18 165 with a plate thickness of 50 mm is less than 20, preferably less than 10 and in particular less than 5 [N.cm -3 ];
• Flammability according to DIN 4102 at least normal, preferably flame-retardant
• the foams based on melamine / formaldehyde condensation products which are used according to the invention are open-pore. A microscopic examination of the foams shows that the foam structure contains a large number of interconnected, three-dimensionally branched webs.
• Melamine / formaldehyde Hyd resin foams are, for example, sufficiently elastic if the webs meet the conditions described in EP-A-0 017 672, ie the average ratio of length to thickness of the webs is greater than 10: 1, preferably greater than 12: 1 and in particular greater than 15: 1 and the density of the webs is more than 1.10, preferably more than 1.20 and in particular more than 1.30 g / cm 3 .
• the length and thickness of the webs are determined microscopically, for example, the density of the foam webs is determined by immersing the foams in a suitable liquid such as isopropanol. Archimedean principle determined, cf. EP-A-0 017 672.
• the foam is annealed at 120 to 300 ° C. for a period of 1 to 180 minutes. It is preferably heated to temperatures of 120 and 260 ° C., particularly preferably from 150 to 250 ° C., for 3 to 60 minutes, water, blowing agent and formaldehyde being largely removed and the foam resin being post-cured.
• This temperature treatment can take place immediately after the foam production in the same apparatus or in a downstream apparatus; however, it can also be carried out at a later point in time independently of the foaming process. Tempered foams show a much lower tendency to shrink and have a lower equilibrium moisture content than unheated products.
• the formaldehyde emission of the tempered foams is also greatly reduced compared to the formaldehyde emission of the untempered products.
• the release of formaldehyde is less than 100 mg formaldehyde / kg foam, preferably less than 20 mg .
• Formaldehyde / kg foam (measured according to the EU standard ISO 14184-1).
• the foams can be produced as sheets, blocks or sheets with a height of up to 2 m or as foam sheets with a thickness of a few mm, e.g. 0-, 5 to 7mm.
• the preferred foam height (in the direction of foaming) is when using microwaves, the frequency 2.45 GHz between 10 cm and 100 cm. All desired plate or fleece thicknesses can be cut out from such foam blocks.
• the foams are hydrophilized in process step (c), the hydrophilization also being able to be carried out during the annealing, for example by flowing hot air through the melamine / formaldehyde resin foam and removing all volatile constituents Adds hydrophilizing substances to this tempering air, for example in the form of an aerosol. In this way, a hydrophilic achieved without having to treat the foams with a hydrophilizing agent.
• the necessary hydrophilicity in process step (c) can be generated in different ways, e.g. by treatment with at least one hydrophilizing agent and / or ozone, a corona discharge or a plasma.
• the treatment of the foam with a hydrophilizing agent can involve, for example, adsorption of a more hydrophilic component, for example surfactants or hydrophilic polymers, which may have a hydrophobic modification, or chemical bonding of hydrophilic reagents, for example polyamines, polyepoxides or polycarboxylic acids • the top surface of the foam act.
• a hydrophilic component for example surfactants or hydrophilic polymers, which may have a hydrophobic modification, or chemical bonding of hydrophilic reagents, for example polyamines, polyepoxides or polycarboxylic acids • the top surface of the foam act.
• hydrophilic reagents for example polyamines, polyepoxides or polycarboxylic acids • the top surface of the foam act.
• the surface of the foam can also be rendered hydrophilic by applying crosslinked polymers or a crosslinked, hydrophilic shell, for example by
• Monomers or polymers that can react with an added crosslinker e.g. Polycarboxylic acids in combination with multifunctional epoxides, polyhydric alcohols or polyamines, polyamines in combination with multifunctional epoxides, acrylates or esters
• the hydrophilizing agents are normally used in dissolved form by dissolving them in a solvent. They can also be applied in the form of aqueous dispersions or dispersions in an organic solvent to the foams to be hydrophilized.
• the hydrophilization can e.g. by immersing the melamine / formaldehyde foam body in the liquid which contains the hydrophilizing agent in dissolved or in dispersed form.
• the liquid with the dissolved or the dispersed hydrophilizing agent can also be applied by spraying onto the foam surface. The solvent is then removed from the hydrophilized foam body, e.g. by drying the foam.
• the hydrophilizing agent reacts with the melamine / formaldehyde resin foam to be hydrophilized or is adsorbed on the polymer surfaces.
• the amount of hydrophilizing agent added is such that, on the one hand, hydrophilization takes place without that on the other hand the mechanical properties of the foam (flexibility) are disturbed.
• the hydrophilizing agent is preferably added in an amount such that the resulting amount of hydrophilizing agent is 0.05 to 100% by weight, preferably 0.1 to 50% by weight and in particular 0.2 to 30% by weight. %, based on the foam.
• Hydrophilization of the melamine in / formaldehyde foam is possible, for example, by the action of at least one surfactant on the foam.
• Skin-friendly surfactants are particularly preferably added.
• skin-friendly hydrophilizing agents are oil-soluble surfactants such as sorbitan fatty acid esters, polyglycerol fatty acid esters and polyoxyethylene.
• examples of 'the above type surfactants are Trioda 20, a commercially verhegba- rer polyglycerol esters, and EMSORB ® 2502 a sorbitan sesquioleate.
• Preferred sorbitan fatty acid esters are sorbitan laurate (e.g.
• SPAN ® 20 sorbitan monooleate
• SPAN ® 80 sorbitan monooleate
• SPAN ® 85 sorbitan trioleate
• sorbitan monooleate - sorbitan monooleate -
• Particularly preferred is the combination of sorbitan monooleate and sorbitan trioleate in a weight ratio of greater than or equal to 3: 1, particularly preferably 4: 1.
• Combinations of sorbitan laurate with certain polyglycerol fatty acid esters are also used as hydrophilizing agents.
• Polyglycerol fatty acid esters are obtained from ester-forming polyglycerols and fatty acids, cf. for example US-A-3, 637, 774.
• the polyglycerols are characterized by a high proportion of linear (especially acyclic) diglycerols, a low proportion of tri- or higher. rer polyglycerols, and a small proportion of cyclic diglycerins.
• the weight ratio of sorbitan laurate to polyglycerol fatty acid ester is normally between 10: 1 and 1:10, preferably between 4: 1 and 1: 1.
• the products are modified hydrophilically. This modification can be carried out by incorporating amino, carboxy or hydroxyl groups. It is also possible to connect oligo- or polyethylene glycol side chains.
• acylated polyamines which can be obtained, for example, by reacting polyamines with monobasic carboxylic acids.
• Suitable polyamines are, for example, polyalkylene polyamines with average molecular weights from 300 to 1 million, preferably from 500 to 500,000.
• Polyalkylene polyamines which are preferably used are polyethyleneines.
• the monobasic carboxylic acids usually have 1 to 18 carbon atoms, for example formic acid, acetic acid, propionic acid, lauric acid, palmitic acid or stearic acid. In some cases, it is advantageous to react mixtures of a long-chain monocarboxylic acid 5 in succession or together with a polyalkylene polyamine.
• the esters of the carboxylic acids can also be used.
• the NH 2 or NH groups of the polyalkylene polyamines are amidated. In this way, for example 5 to 10 100, preferably 15 to 85% of the nitrogen atoms in the polyalkylene polyamine can be acylated.
• hydrophilizing agents are polymers that
• tertiary amino groups of component ii) are present in the polymer in the form of ammonium groups.
• Charged cationic groups can be obtained from the tertiary amine nitrogen of the compounds of component ii)
• the polymer either by protonation or by quaternization. At least some of the tertiary amino groups are then present in the polymer in the form of its reaction products with at least one neutralizing (protonating) and / or quaternizing agent.
• the polyisocyanates i) are preferably selected from compounds with 2 to 5 isocyanate groups, isocyanate prepolymers with an average number of 2 to 5 isocyanate groups and mixtures thereof. Connections that are additional are also suitable
• 35 to or instead of free isocyanate groups have functional groups which release isocyanate groups or react as isocyanate groups. These include e.g. B. capped isocyanate groups, uretdione groups, isocyanurate groups and / or compounds containing biuret groups.
• the compounds containing isocyanurate groups are in particular simple triisocyanate isocyanurates, ie cyclic trimers of diisocyanates, or mixtures with their higher homologues containing more than one isocyanurate ring.
• Suitable compounds of component ii) are, for example, tertiary amines in which the amine nitrogen has three 5 substituents, which are preferably hydroxyalkyl and / or aminoalkyl groups.
• Compounds of component ii) which are preferably used are, for example, bis (aminopropyl) methylamine, Bis (aminopropyl) piperazine, methyldiethanolamine and mixtures of these compounds.
• cationic synthetic polymers which contain amino and / or ammonium groups can be used as cationic polymers.
• cationic polymers are polymers containing vinylamine units, polymers containing vinylimidazole units, polymers containing quaternary vinylimidazole units, condensates of imidazole and epichlorohydrin, crosslinked polyamidoamines, crosslinked polyamidoamines grafted with ethyleneimine, polyethyleneimines, alkoxylated polyethyleneimines, crosslinked polyethyleneimines Polyethyleneimines, polyamines, amine-epichlorohydrin polycondensates, water-soluble polyadducts made from multifunctional amines with multifunctional epoxides, alkoxylated polyamines, polyallylamines, polydimethyldiallylammonium chlorides, polymers containing basic (meth) acrylamide or ester units, basic quaternary or (meth) acrylamide or (meth) acrylamides polymers containing
• Cationic polymers are also understood to mean amphoteric polymers which have a net cationic charge, i.e. the polymers contain both anionic and cationic monomers copolymerized, but the molar proportion of the cationic units contained in the polymer is greater than that of the anionic units.
• Polymers containing vinylamine units are prepared, for example, from open-chain N-vinylcarboxylic acid amides of the formula
• R 1 and R 2 may be the same or different and stand for hydrogen and C ⁇ ⁇ to C 6 alkyl.
• the monomers mentioned can be polymerized either alone, as a mixture with one another or together with other monoethylenically unsaturated monomers. Preferably one starts from homo- or Copolymers of N-vinylformamide.
• Polymers containing vinylamine units are known, for example, from US Pat. No. 4,421,602, US Pat. No. 5,334,287, EP-A-02 16 387 and EP-A-0 251 182. They are obtained by hydrolysis of polymers which contain the monomers of the formula I in copolymerized form with acids, bases or enzymes.
• copolymerizable compounds into consideration.
• examples include vinyl esters of saturated carboxylic acids of 1 to 6 carbon atoms such as vinyl formate, vinyl acetate, vinyl propionate and vinyl butyrate and vinyl ethers such as C 1 -C 6 -alkyl vinyl ether, e.g. Methyl or ethyl vinyl ether.
• vinyl esters of saturated carboxylic acids of 1 to 6 carbon atoms such as vinyl formate, vinyl acetate, vinyl propionate and vinyl butyrate
• vinyl ethers such as C 1 -C 6 -alkyl vinyl ether, e.g. Methyl or ethyl vinyl ether.
• Other suitable comonomers are examples of suitable comonomers.
• C 3 - to C 6 -carboxylic acids for example acrylic acid, methacrylic acid, maleic acid, crotonic acid, itaconic acid and vinyl ester acid and their alkali metal and alkaline earth metal salts, esters, amides and nitriles of the carboxylic acids mentioned, for example methyl acrylate, 1 methyl methacrylate, ethyl acrylate and
• carboxylic acid esters are derived from glycols or polyalkylene glycols, only one OH group being esterified in each case, e.g. Hydroxyethyl acrylate, hydroxyethyl methacrylate,
• esters of ethylenically unsaturated carboxylic acids with amino alcohols such as, for example, dimethylamino
• Suitable quaternizing agents are, for example, methyl sulfate, diethyl sulfate, methyl chloride,
• Suitable comonomers are amides of ethylenically unsaturated carboxylic acids such as acrylamide, methacrylamide and N-alkyl mono- and diamides of monoethylenically unsaturated carboxylic acids with alkyl residues of 1 to 6 carbon atoms, for example N-methylacrylamide, N, N-dimethylacrylamide, N -Methyl methacrylamide, N-ethyl acrylamide, N-propylacrylamide and tert.
• amides of ethylenically unsaturated carboxylic acids such as acrylamide, methacrylamide and N-alkyl mono- and diamides of monoethylenically unsaturated carboxylic acids with alkyl residues of 1 to 6 carbon atoms, for example N-methylacrylamide, N, N-dimethylacrylamide, N -Methyl methacrylamide, N-ethyl acrylamide, N-propylacrylamide and tert.
• Butylacrylamide and basic (Meth) acrylamides such as, for example, dimethylaminoethyl acrylamide, dimethylaminoethyl methacrylamide, diethylaminoethyl acrylamide, diethylaminoethyl methacrylamide, dimethylaminopropylacrylamide, diethylaminopropylacrylamide, dimethylaminopropyl methacrylamide and diethylaminopropyl methacrylamide.
• N-vinylpyrrolidone N-vinylcaprolacta
• acrylonitrile methacrylonitrile
• N-vinylimidazole substituted N-vinylimidazoles
• N-vinyl-2-methylimidazole N-vinyl-4-methylimidazole
• N-vinyl-5-methylimidazole N-vinyl-2-ethylimidazole
• N-vinylimidazolines such as N-vinylimidazoline, N-vinyl-2- methylimidazoline and N-vinyl-2-ethylimidazoline.
• N-vinylimidazoles and N-vinylimidazolines are also used in neutralized or in quaternized form with mineral acids or organic acids, the quaternization preferably being carried out with dimethyl sulfate, diethyl sulfate, methyl chloride or benzyl chloride.
• Diallyldialkylammonium halides such as e.g. Diallyldimethylammonium chloride.
• monomers containing sulfo groups such as vinylsulfonic acid, allylsulfonic acid, methallylsulfonic acid, styrene sulfonic acid, the alkali metal or ammonium salts of these acids or 3-sulfopropyl acrylic acid are suitable as comonomers, the amphoteric copolymer content of cationic units exceeding the content of anionic units , so that the polymers have a total cationic charge.
• copolymers contain, for example
• vinylamine unit-containing polymers it is preferable to start from homopolymers of N-vinylformamide or from copolymers which are obtained by copolymerizing
• the degree of hydrolysis being, for. B. is 0.1 to 100 mol%.
• the polymers described above are hydrolysed by known processes by the action of acids, bases or enzymes.
• the resulting polymerized monomers of the formula I given above are formed by splitting off the grouping
• R 2 has the meaning given for it in formula I, polymers, the vinylamine units of the formula CH 2 .
• R 1 has the meaning given in formula I. If acids are used as the hydrolysis agent, units III are present as the ammonium salt.
• the homopolymers of the N-vinylcarboxamides of the formula I and their copolymers can be from 0.1 to 100, preferably from 70 to. 100 mol% be hydrolyzed. In most cases, the degree of hydrolysis of the homo- and copolymers is 5 to 95 mol%. The degree of hydrolysis of the homopolymers is synonymous with the vinylamine units in the polymers. In the case of copolymers which contain vinyl esters in copolymerized form, in addition to the hydrolysis of the N-vinylformamide units, hydrolysis of the ester groups can occur with the formation of vinyl alcohol units. This is particularly the case when the copolymers are hydrolysed in the presence of sodium hydroxide solution.
• Polymerized acrylonitrile is also chemically changed during the hydrolysis. This creates, for example, amide groups or carboxyl groups.
• the homo- and copolymers containing vinylamine units can optionally contain up to 20 mol% of amidine contain units which are formed, for example, by reaction of formic acid with two adjacent amino groups or by intramolecular reaction of an amino group with an adjacent amide group, for example of polymerized N-vinylformamide.
• the molar masses of the polymers containing vinylamine units are, for example, 1000 to 10 million, preferably 10,000 to 5 million (determined by light scattering). This molar mass range corresponds, for example, to K values of 5 to 300, preferably 10 to 250 (determined according to H. Fikentscher in 5% aqueous sodium chloride solution at 25 ° C. and a polymer concentration of 0.5% by weight.
• the polymers containing vinylamine units are preferably used in salt-free form.
• Salt-free aqueous solutions of polymers containing vinylamine units can be prepared, for example, from the salt-containing polymer solutions described above with the aid of ultrafiltration on suitable membranes at separation limits of, for example, 1000 to 500,000 daltons, preferably 10,000 to 300,000 daltons.
• the aqueous solutions of other polymers containing amino and / or ammonium groups described below can also be obtained with the aid of ultrafiltration in a salt-free form.
• Polyethyleneimines are prepared, for example, by polymerizing ethylenei in aqueous solution in the presence of acid-releasing compounds, acids or Lewis acids.
• Polyethyleneimines have, for example, molecular weights of up to 2 million, preferably from 200 to 500,000. Polyethyleneimines with molecular weights of 500 to 100,000 are particularly preferably used.
• water-soluble crosslinked polyethyleneimines which can be obtained by reacting polyethyleneimines with crosslinking agents such as epichlorohydrin or bischlorohydrin ethers of polyalkylene glycols having 2 to 100 ethylene oxide and / or propylene oxide units.
• Amidic polyethyleneimines are also suitable, which are obtainable, for example, by amidating polyethyleneimines with C 1 -C 22 -monocarboxylic acids.
• Other suitable cationic polymers are alkylated polyethyleneimines and alkoxylated polyethyleneimines. In alkoxylation, 1 to 5 ethylene oxide or propylene oxide units are used, for example, per NH unit in polyethyleneimine.
• Suitable amino and / or. Polymers containing ammonium groups are also polyamidoamines, which can be obtained, for example, by condensing dicarboxylic acids with polyamines.
• Suitable polyamidoamines are obtained, for example, by reacting dicarboxylic acids with 4 to 10 carbon atoms with polyalkylene polyamines which contain 3 to 10 basic nitrogen atoms in the molecule.
• Suitable dicarboxylic acids are for example such as succinic acid, maleic acid, adipic acid, glutaric acid, suberic acid, sebacic acid or terephthalic acid. Mixtures of dicarboxylic acids can also be used in the preparation of the polyamidoamines, as can mixtures of several polyalkylene polyamines.
• Suitable polyalkylene polyamines are, for example, diethylenetriamine, triethyleritetramine, tetraethylenepentamine, dipropylenetriamine, tripropylenetetramine, dihexamethylenetriamine, aminopropylethylenediamine and bis-a-inopropylethylenediamine.
• the dicarboxylic acids and polyalkylene polyamines are heated to higher temperatures to produce the polyamidoamines, for example to temperatures in the range from 120 to 220, preferably 130 to 180 ° C.
• the water generated during the condensation is removed from the system.
• Lactones or lactams of carboxylic acids having 4 to 8 carbon atoms can optionally also be used in the condensation.
• 0.8 to 1.4 moles of a polyalkylene polyamine are used per mole of a dicarboxylic acid.
• polymers containing amino groups are polyamidoamines grafted with ethyleneimine. They can be obtained from the polyamidoamines described above by reaction with ethyleneimine in the presence of acids or Lewis acids such as sulfuric acid or boron trifluoride etherates at temperatures of, for example, 80 to 100.degree. Compounds of this type are described for example in DE-B-24 34 816.
• the optionally crosslinked polyamidoamines which are optionally additionally grafted with ethyleneimine before crosslinking, are also suitable as cationic polymers.
• the crosslinked polyamidoamines grafted with ethyleneimine are water-soluble and have, for example, an average molecular weight of 3000 to 1 million daltons.
• Typical crosslinkers are, for example , epichlorohydrin or bischlorohydrin ethers of alkylene glycols and polyalkylene glycols.
• cationic polymers containing amino and / or ammonium groups are polydiallyldimethylammonium chloride. Polymers of this type are also known.
• suitable cationic polymers are copolymers of, for example, 1 to 99 mol%, preferably 30 to 70 mol% of acrylamide and / or methacrylamide and 99 to 1 mol%, preferably 70 to 30 mole% of cationic monomers such as dialkylaminoalkyl acrylamide , esters and / or methacrylamide and / or ethacrylate ester.
• the basic acrylamides and methacrylamides are also preferably in neutralized or quaternized form with acids.
• Examples include N-trimethylammonium ethyl acrylamide chloride, N-trimethyl ammonium ethyl methacrylamide chloride, N-Trimethylammoniumethylmethacrylesterchlorid, N-Trimethylammoniumethylacrylesterchlorid, lacrylamidmethosulfat Trimethylammoniumethy-, sulfate Trimethylammoniumethylmethacrylamidmetho-, N-Ethyldimethylammoniumethylacrylamidethosulfat, ethyl dimethylammoniumethylmethacrylamidethosulfat, trimethyl 5 propylacrylamidchlorid, Trimethyla moniumpropylmethacrylamidchlo- chloride, Trimethylammoniumpropylacrylamidmethosulfat, trimethylammonium niumpropylmethacrylamidmethosulfat 'and N-Ethyldimethylammonium- propylacrylamidethosulfat. Trimethylammonium
• (Meth) acrylamide polymers are diallyldimethylammonium halides and basic (meth) crylates. Suitable are e.g. Copolymers of 1 to 99 mol%, preferably 30 to 70 mol%
• the quaternization can take place, for example, with methyl chloride or with dimethyl sulfate.
• Polyallylamines are also suitable as cationic polymers which have amino and / or ammonium groups 25.
• Polymers of this type are obtained by homopolymerizing allylamine, preferably in acid neutralized or in quaternized form, or by copolymerizing allylamine with other monoethylenically unsaturated monomers described above as 30 comonomers for N-vinylcarboxamides.
• the cationic polymers have e.g. K values from 8 to 300, preferably 15 to 180 (determined according to H. Fikentscher in 5% aqueous saline solution at 25% and a polymer concentration 35 of 0.5% by weight). At a pH of 4.5, for example, they have a charge density of at least 1, preferably however. at least 4 meq / g polyelectrolyte.
• Preferred cationic polymers are polydimethyldiallylammonium chloride, polyethyleneimine, polymers containing vinylamine units, copolymers of acrylamide or methacrylamide containing copolymerized basic monomers, polymers containing lysine units or mixtures thereof.
• Examples of preferred cationic polymers are: 45 Polylysines with M w of 250 to 250,000, preferably 500 to 100,000, and lysine co-condensates with molecular weights M w of 250 to 250,000, wherein the co-condensable component is, for example, amines, polyamines, ketene dimers, lactams, alcohols, alkoxylated amines, alkoxylated alcohols and / or uses non-proteinogenic amino acids,
• Vinylamine homopolymers 1 to 99% hydrolyzed polyvinylformamides, copolymers of vinylformamide and vinyl acetate, vinyl alcohol, vinylpyrrolidone or acrylamide with molecular weights of 3,000-500,000,
• Vinylimidazole hoopolymers vinylimiazole copolymers with vinylpyrrolidone, vinylformamide, acrylamide or vinyl acetate with molecular weights from 5,000 to 500,000 and their quaternary derivatives,
• polymers containing basic (meth) acrylamide or ester units basic polymers containing quaternary (meth) acrylamide or ester units with molecular weights from 10,000 to 2,000,000.
• Polymers containing amino groups which are applied as hydrophilizing agents to the melamine / formaldehyde resin foams, can optionally be crosslinked thereon.
• Crosslinking of the foams treated with polymers containing amino groups is achieved, for example, by reaction with at least bifunctional crosslinking agents such as epichlorohydrin, bischlorohydrin ethers of polyalkylene glycols, polyepoxides, multifunctional esters, multifunctional acids or multifunctional acrylates.
• the foams according to the invention based on melamine / formaldehyde resins are used in hygiene articles for the absorption, distribution and immobilization of body fluids, in particular blood. Their hydrophilic character allows water body fluids to be absorbed spontaneously. The open-cell structure ensures rapid transport into the foam interior.
• the hygiene articles which contain the foams to be used according to the invention are essentially borrowed from baby diapers, incontinence products, feminine hygiene products, wound dressings or wound dressings.
• the foams based on melamine / formaldehyde resin for use in the hygiene sector according to the invention are open-pore and hydrophilic.
• the drop absorption rate of the melamine / formaldehyde foams according to the invention is less than 5 seconds, preferably less than 2 seconds, particularly preferably less than 1 second.
• the open-cell, elastic foams are preferably incorporated as flat structures in the form of foam nonwovens with a thickness of 0.1 to 10 mm, preferably 1 to 5 mm in hygiene products such as baby diapers, incontinence and feminine hygiene articles or as wound dressings or in dressing materials.
• the density of the foams is, for example, 5 to 200 g / 1, preferably 10 to 50 g / 1.
• the foams have preferably a ridge structure to have a specific 'surface, determined by the BET method, of more than 0.5 m 2 / g, eg 1 to 7 m2 / g, verhe- gene via a Free Swell Capacity of more than 20 g / g, for example 80 to 120 g / g and, when wet, have a tensile strength of> 60 07 m 2 , for example 100 to 600 J / m2.
• Topsheet and absorbent core Hygiene articles of this type are known and are described, for example, in DE-G-92 18 991 and EP-A-0 689 818.
• the absorbent composition is fixed between the top sheet and back sheet.
• elastic cuffs and self-adhesive closures can be integrated into the hygiene article.
• a preferred structure of a hygiene article is known, for example, from US Pat. No. 3,860,003.
• the melamine / formaldehyde foam layer serves as an absorbing intermediate layer without further layers. It is then simultaneously an acquisition or acquisition / distribution layer and storage layer.
• the absorbent intermediate layer consists of (a) a melamine / formaldehyde foam layer which acts as an acquisition or acquisition / distribution layer and (b) one Storage layer containing 10 - 100% by weight of highly swellable hydrogel.
• the storage layer is either a layer of a hydrogel or compositions that contain 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 absorbent intermediate 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 consisting of a cellulose fiber mixture (air-laid web, wet laid web) or synthetic polymer fibers (meltblown web, spunbonded web) or a mixed fiber structure made of cellulose fibers and synthetic fibers. Furthermore, open-pore foams or the like can be used for the installation of 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.
• at least one of 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-pore foams, perforated films, elastomers or fabrics made of fiber material can be used as the layer material.
• the layer material When the memory layer consists of a composition of layers, the layer material should 'have a pore structure whose Porenabmes- measurements are small enough to the • highly swellable ⁇ ydrogelparti- angles retain.
• the above examples for the composition of the storage layer also include laminates of at least two layers, between which highly swellable hydrogels can be installed and fixed.
• the storage layer made 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 can be present in the above-mentioned compositions of the storage layer, for example in a weight fraction of 10 to 100% by weight, preferably 40 to 100% by weight and in particular preferably 70 to 100% by weight. If the composition of the storage layer described above is a fiber matrix, the absorbent composition results a mixture of fiber materials and highly swellable hydrogels.
• the storage layer can contain a variety of fiber materials that are used as fiber networks or matrices. Included in the present invention are both fibers of natural origin (modified or unmodified) and synthetic fibers.
• cellulosic fibers include those commonly used in absorption products such as fleece pulp and cotton type pulp.
• the materials softwood or hardwood
• manufacturing processes such as chemical pulp, semi-chemical pulp, chemothermal mechanical pulp (CTMP) and bleaching processes are not particularly limited.
• CMP chemothermal mechanical pulp
• natural cellulose fibers such as cotton, flax, silk, wool, jute, ethyl cellulose and cellulose acetate are used.
• Suitable synthetic fibers are made from polyvinyl chloride, polyvinyl fluoride, polytetrafluoroethylene, polyvinylidene chloride, polyacrylic compounds such as ORLON, polyvinyl acetate, polyethyl vinyl acetate, soluble or insoluble polyvinyl alcohol.
• thermoplastic polyolefin fibers such as polyethylene fibers (PULPEX), polypropylene fibers and polyethylene-polypropylene bicomponent fibers, polyester fibers such as polyethylene terephthalate fibers (DACRON or K0-DEL), copolyesters, polyvinyl acetate, polyethyl vinyl acetate, polyvinyl chloride, polyvinylidene chloride, polyvinylidene chloride Copo- lyamide, polystyrene and copolymers of the aforementioned polymers, as well as bicomponent fibers of polyethylene terephthalate polyethylene isophthalate copolymer, 'polyethylvinyl acetate / polypropylene, polyethylene / polyester, polypropylene / polyester, Copolye- art / polyester, polyamide fibers (nylon), polyurethane fibers, P lystyrene fibers and polyacrylonitrile fibers.
• PVPEX polyethylene fibers
• Polyolefin fibers, polyester fibers and their two-component fibers are preferred. Furthermore, heat-sensitive two-component fibers made of polyolefin of the shell-core type and side-by-side type are preferred because of their excellent dimensional stability after the 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 extension of the present one Pore dimensions after heat treatment. 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, which results in an equally continuous increase in the particle sizes.
• 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 S C and 175 S C. At these temperatures, no damage to the cellulose fibers is yet to be expected.
• the synthetic fibers described above may, for example, a length of 1 to '200 mm and have a diameter of 0.1 to 100 denier (grams per 9000 meters).
• 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 fibers can have various shapes, for example fabric-like, narrow cylinder-like, cut / split yarn-like, staple fiber-like or continuous fiber-like.
• the fibers in the absorbent composition according to the invention can be hydrophilic or hydrophobic. Combinations of both fiber shapes are possible. According to the definition by Robert F. Gould in the publication "Contact Angle, Wettability and Adhesion", American Chemical Society (1964), a fiber is said to be hydrophilic if the contact angle between the liquid and the fiber (or its surface) is less than 90 e , or when the liquid tends to spread spontaneously on the same surface. As a rule, both processes are coexistent. Conversely, a fiber is said to be hydrophobic if a contact angle of greater than 90 e 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 the absorption ultimately takes place.
• Suitable hydrophilic fibers for use in the absorbent intermediate layer according to the invention are, for example, cellulose fibers, modified cellulose fibers, rayon, polyester fibers such as eg. B. polyethylene terephthalate (DACRON ® ), and hydrophilic Ny- Ion (HYDROFIL®).
• Suitable hydrophilic fibers can also be obtained by hydrophilizing hydrophobic fibers, such as, for example, treating thermoplastic fibers obtained from polyolefins (such as, for example, polyethylene or polypropylene, polyamides, polystyrenes, polyurethanes, etc.) with surfactants or silica.
• polyolefins such as, for example, polyethylene or polypropylene, polyamides, polystyrenes, polyurethanes, etc.
• surfactants or silica such as, for example, cellulosic fibers 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, whether 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, whereby 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.
• fiber stiffening can be achieved in different ways.
• fiber stiffening can be achieved by adding suitable coatings / coatings to the fiber material.
• suitable coatings / coatings include, for example, polyamide-epichlorohydrin coatings (Kymene 557 H, polyacrylic amide coatings (described in U.S. Patent 3,556,932 or as a Parez® 631 NC brand product, 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 -Cs dialdehydes, C 2 -Cs monoaldehydes with acidic 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 cross-linked cellulose fibers are known, cf. for example WO-A-91/11162.
• 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.
• a hydrophilized fleece made of an open-cell, elastic melamine / formaldehyde resin foam with very low formaldehyde emissions is used as or in the absorbent intermediate layer.
• the dimensions (thickness) of the absorbent intermediate layer when used with the functionality as an absorbent core are generally between 0.5 and 10 mm, preferably between 1 and 5 mm.
• the thickness is between 0.1 and 10 mm; preferably between 0.5 and 3 mm.
• the topsheet can be produced in various ways, such as woven, non-woven, spun or combed fiber mix. Combed fiber mixture is preferably used, which is thermally bound to the top sheet.
• the weight per unit area of the top sheet is preferably 18 to 25 g / m 2 , a tensile strength of at least 400 g / cm in the dry state and 55 g / cm in the wet state.
• Liquid-impermeable materials such as, for example, polyolefins (for example polyethylene backsheets), are usually used as the backsheet in order to protect the wearer's clothing from possible leakage.
• polyolefins for example polyethylene backsheets
• the individual layers from which the hygiene articles are constructed are connected to one another by known methods, such as fusing the layers by heat treatment, adding hot melt adhesives, latex binders, etc.
• the absorbent intermediate layer is positioned between the top sheet and back sheet. measurement methods
• any suitable gravimetric method can be used to determine the density of the foam.
• the mass of solid foam per unit volume of foam structure is determined.
• a method for determining the density of the foam is described in ASTM Method No. D 3574-86, Test A. This method was originally developed to determine the density of urethane foams, but can also be used for this purpose. Then, in the case of a preconditioned sample, as described in the method, its dry mass and volume are determined at 22 +/- 2 ° C. Volume determinations of larger sample dimensions are carried out under normal pressure.
• This method determines the free swellability of the open-cell, elastic melamine / formaldehyde foam.
• a sample of a suitable size for example a sample with an area of approximately 1 cm ⁇ 1 cm, is cut out and weighed out of the foam sample. This sample is placed in an excess of 0.9% by weight NaCl solution for at least 30 minutes (at least 0.83 l of sodium chloride solution / 1 g of foam). The foam sample is then drained for 10 minutes by hanging it at a corner, being careful not to compress the sample. The amount of liquid absorbed is determined by weighing the foam sample.
• the open-cell, elastic melamine / formaldehyde foam is cut into 1.5 mm, 2 mm or 4 mm thick layers.
• a commercially available diaper is carefully cut open, the high-loft serving as the acquisition medium is removed and the open-cell elastic melamine / formaldehyde foam layer is inserted instead.
• the diaper is closed again.
• the Synthetic urine replacement solution is applied through a plastic plate with a ring in the middle (inner diameter of the ring 6.0 cm, height 4.0 cm).
• the plate is loaded with additional weights so that the total load on the diaper is 13.6 5 g / cm 2.
• the plastic plate is placed on the diaper so that the center of the diaper is also the center of the feed ring. 60 ml of 0.9% by weight sodium chloride solution are applied three times.
• the saline solution is measured in a measuring cylinder and through the ring in the plate in one
• the specific surface is determined using the BET method in accordance with DIN 66132.
• the formaldehyde content in the solution obtained is determined by the acetyl acetone method. , -
• Comparative Example 1 45 75 parts of a spray-dried melamine / formaldehyde precondensate (molar ratio 1: 3) were dissolved in 25 parts of water. This resin solution was 3% formic acid, 2% of a Na -C 2 / C 18 alkane sulfonate and 19% pentane, each based on the resin, added. The mixture was stirred vigorously and then foamed in a polypropylene foam mold by irradiation with microwave energy at 2.54 GHz. The foam was dried at 5 100 2 C and then annealed at 220 S C for 30 min. The melamine / formaldehyde foam thus produced was hydrophilic and had a density of 10 g / l.
• the formaldehyde release measured after 1 h storage at 40 ° C. in water was 150 mg formaldehyde / kg foam.
• the free absorption capacity (FSC), 10 determined by the teabag test, was 103 g / g.
• the foam had a specific surface area, determined by the BET method, of 5.3 m 2 / g.
• the foam is dried and tempered as described in Comparative Example 1.
• the foam produced in this way was hydrophobic and its density was also 10 g / l.
• the release of formaldehyde was less than 20 mg formaldehyde / kg foam.
• the melamine-formaldehyde adhesive foam hydrophilized according to Example 10 was cut into layers 2 mm thick. A commercially available diaper was carefully cut open, the highloft removed and the 2 mm thick foam layer inserted instead. The diaper was closed again. After that, the times for recording 3 consecutive were determined Additions of 60 ml synthetic urine were required. The measured values are given in Table 2.
• a foam hydrophilized according to example 6 was incorporated into a diaper and the acquisition times were determined. The results are shown in Table 2.
• the melamine / formaldehyde condensate foam produced according to Comparative Example 1 was incorporated into a diaper as described in Example 16 '. The acquisition times were then determined. The results are shown in Table 2.
• Table 2 shows that the acquisition times of the hydrophilized, low-formaldehyde foam are significantly better than those of a commercially available diaper and are at the same level as for the original high-formaldehyde foam, which was produced according to Comparative Example 1.

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