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
  • C08G18/00—Polymeric products of isocyanates or isothiocyanates
  • C08G18/06—Polymeric products of isocyanates or isothiocyanates with compounds having active hydrogen
  • C08G18/28—Polymeric products of isocyanates or isothiocyanates with compounds having active hydrogen characterised by the compounds used containing active hydrogen
  • C08G18/40—High-molecular-weight compounds
  • C08G18/42—Polycondensates having carboxylic or carbonic ester groups in the main chain
  • C08G18/4236—Polycondensates having carboxylic or carbonic ester groups in the main chain containing only aliphatic groups
• • 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
  • C08G2110/00—Foam properties
  • C08G2110/0041—Foam properties having specified density
  • C08G2110/0066—≥ 150kg/m3
• • 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
  • C08G2110/00—Foam properties
  • C08G2110/0091—Aerogels; Xerogels

Definitions

• the invention relates to processes for the preparation of porous polyisocyanate polyaddition products, preferably polyurethanes and / or polyureas, particularly preferably polyurethanes, which may optionally contain urea structures, preferably Polyurethanform stresses ⁇ , in particular with airgel-like structure based on polyurethanes, by reaction of ( a) isocyanates with (b) isocyanate-reactive compounds in the presence of preferably isocyanate-inert solvent (f) and preferably subsequent removal of the Amsterdamsmitteis (f) from the polyurethane.
• the invention furthermore relates to porous polyisocyanate polyaddition products obtainable in this way, preferably polyurethanes and / or polyureas, more preferably polyurethanes, preferably polyurethane moldings, particularly preferably airgel-like structures based on polyurethanes, in particular porous polyurethanes having a density between 30 kg / m 3 and 500 kg / m 3 and an intrinsic surface> 50 m 2 / g determined by nitrogen sorption according to DIN 66131 based on isocyanate-reactive compounds (b) having a functionality towards isocyanates, preferably hydroxyl groups of at least 6, preferably 6 to 100, more preferably 10 to 60 and a molecular weight of at least 1000 g / mol, preferably 1500 g / mol to 10000 g / mol, more preferably 1500 g / mol to 6000 g / mol, in particular 2000 g / mol to 6000 g / mol.
• Porous polyisocyanate polyaddition products prepared in the presence of a solvent and the preparation of these products are well known.
• US describes 3574150 open-celled polyurethanes having a porosity of at least 50% and a density 100 to 500 kg / m 3, containing, however, spherical by a precipitation process particulate structures in the micrometer range and polyaryl polyalkylene polyisocyanates (polymeric MDI) based
• WO 96/36654, WO 96/37539 and WO 98/44028 disclose aerogels based on isocyanurates.
• WO 95/03358 describes aerogels generally based on isocyanates.
• airgel in the sense of the cited documents means that a fluid in the supercritical state is removed from the gel body in the drying step WO 98/44013 and WO 00/24799 describe the preparation of airgel-type compounds based on isocyanurates, ie Gels which are predominantly obtained by trimerization of isocyanates and for which drying is not necessarily required for supercritical conditions are further described in these documents in addition to the trimerization of the isocyanates also copolymers containing isocyanate-reactive groups, in particular copolymers of styrene and hydroxyacryla - th.
• a further disadvantage of a network based on isocyanurate linkages is that a complete conversion of the isocyanate groups to isocyanurates can only be achieved by long reaction times.
• the object of the present invention was thus to provide processes for the production of porous polyisocyanate polyaddition products, preferably polyurethanes, preferably polyurethane moldings, in particular airgel-like materials based on polyurethanes, by reacting (a) isocyanates with (b) isocyanate-reactive compounds in the presence of preferably inert toward isocyanates solvent! (f) to be developed which is simple, inexpensive and reproducible and which gives products which have very good physical and, in particular, mechanical properties.
• porous products should be developed, which should have the highest possible porosity and at the same time the smallest possible pore size. The porous products should be accessible easily and reproducibly.
• isocyanate-reactive compounds those having a functionality to isocyanates, preferably hydroxyl groups, of at least 6, preferably 6 to 100, more preferably 10 to 60 and a molecular weight, preferably weight average molecular weight of at least 1000 g / mol, preferably 1500 g / mol to 10000 g / mol, more preferably 1500 g / mol to 6000 g / mol.
• a particular advantage of the process according to the invention and therefore of the products according to the invention is their mechanical stability both during the production process in the presence of the solvent and during and after drying.
• the products according to the invention have a low brittleness as desired. Due to the use of the isocyanate-reactive component according to the invention, which is distinguished by its high functionality in combination with the high molecular weight and which can also be described as hyperbranched or contains dendrimeric structures. Due to the high degree of branching of the isocyanate-reactive component, a rigid network is achieved in the polyurethane airgel, which makes it possible to dispense with supercritical conditions during drying and at the same time to produce a material of low brittleness.
• Suitable isocyanate-reactive groups in the isocyanate-reactive compounds (b) are those which have at least one active hydrogen atom. Examples of such groups are hydroxyl groups and / or primary and / or secondary amino groups, preferably hydroxyl groups.
• the isocyanate-reactive compounds (b) according to the invention thus include polyetherpolyalcohols, polyesterpolyalcohols, polyetherpolyester alcohols, polythioetherpolyols, hydroxyl-containing polyacetals and hydroxyl-containing aiiphatic polycarbonates or mixtures of at least two of said polyols.
• Preferred as isocyanate-reactive compounds (b) are ethers and / or esters and / or compounds which contain esters and ether structures. Such compounds are well known and can be prepared by known esterification and / or alkoxylation.
• the isocyanate-reactive compounds according to the invention preferably have a hydroxyl number of at least 100 mg KOH / g, more preferably 150 mg KOH / g to 550 mg KOH / g.
• the hydroxyl number of the polyols is therefore suitable for characterizing the particularly preferred hyperbranched structure of the particularly preferred polyols.
• DB degree of branching
• dendrimer is understood to mean that the degree of branching is 99.9-100%
• the glass transition temperature is preferably from -50 0 C to 140 0 C and in particular from -50 to 100 0 C (measured by DSC 1 according to DIN 53765).
• hyperbranched polymers reference is also made to H. Frey et al., Chem. Eur. J. 2000, 6, no. 14, 2499.
• the preparation of hyperbranched polyalcohols is described, for example, in EP-A 1 501 882 and EP-A 1 537 166.
• Particularly preferred compounds used as isocyanate-reactive compounds are branched ester-containing polyols.
• dendritic polyesters are, for example, the condensation products available from 2,2-dimethylolpropionic acid (bis-MPA) sold by Perstorp AB under the trademarks Boltorn®, e.g. Boltorn® H20, H30 and H40.
• porous polyurethanes The production of porous polyurethanes is well known from the prior art described above. Preference is given to processes in which the reaction of (a) isocyanates with (b) isocyanate-reactive compounds is preferably carried out in the presence of an isocyanate-activating catalyst (d), which is described below by way of example urethane formation catalyzing catalyst, preferably tin and / or titanium organic compound and / or suitable amine, more preferably a tin salt or an amino base, preferably tertiary amine, most preferably dibutyltin salts or tertiary aliphatic amines.
• the catalysts are preferably dissolved together with the isocyanate-reactive compounds (b) in the solvent (T).
• the gelation is started by combining the catalyst-containing solution of the isocyanate-reactive component with the stoichiometric amount of isocyanate.
• the content of catalysts (d) is preferably between 0.02 and 3 wt .-%, particularly preferably between 0.1 and 2 wt .-%, based on the total weight of the porous polyurethane.
• the catalyst can be removed from the polymer by intensive solvent exchange. By selecting the amount of catalyst and concentration of the solvent, the gelation time can be adjusted in the range between a few minutes to hours.
• the porous polyurethanes of the invention are characterized in that the solvent can be removed in the subcritical state during drying of the gel body (p ⁇ p 0 , T ⁇ T C ), preferably by applying a slight vacuum.
• the solvent can be removed in the subcritical state during drying of the gel body (p ⁇ p 0 , T ⁇ T C ), preferably by applying a slight vacuum.
• the polymerization is done from the outset in a solvent that is inherently such that the resulting polyurethane network is mechanically robust enough to withstand the capillary forces of subcritical drying without significant shrinkage.
• reaction components Preference is given to solvents in which initially the reaction components can be homogeneously dissolved, but the polyurethane network obtained therefrom is plasticized as slightly as possible. Furthermore, reaction components are preferred which have a high intrinsic chain stiffness, in particular isocyanates and isocyanate-reactive compounds having a high functionality and degree of branching.
• Component (b) and optionally (c), the generally known from the prior art solvents can be used, which are preferably inert to isocyanates.
• solvents are described in WO 00/24799, page 3, line 28 to page 5, line 14.
• solvent! (T) a solvent in which the isocyanates and isocyanate-reactive components used at 298 K at least 1 wt .-%, based on the total weight of the mixture, are soluble or dispersible and by reacting the (a) isocyanates with the (b) isocyanate-reactive compounds results in a gel body in which the proportion of precipitated reaction product less than 1 wt .-%, based on the total weight of the mixture, est.
• the amount of precipitated product is determined gravimetrically by filtering the reaction mixture through a suitable filter in front of the nip.
• Particularly preferred solvents (f) used are aliphatic ketones and esters, preferably butanol, propanone, ethyl acetate, butyl acetate or aliphatic ethers, preferably tetrahydrofuran, tetrahydropyran.
• the process according to the invention is particularly preferably carried out in such a way that the isocyanates (a) and the isocyanate-reactive compounds are dissolved separately in the same or different, preferably the same solvent (f) and then the two components (a) and (b) are dissolved in each case be reacted in the solvent (f) by mixing.
• the proportion by weight of solvent (f) based on the total weight of the components used in the preparation of the polyurethane foam, including the solvent, is preferably between 50% by weight and 99% by weight, particularly preferably between 60% by weight and 95% by weight. %. If, as shown above, the components (a) and (b) are separately dissolved in the solvent (f), the weight of the solvent (f) in the respective components is preferably between 50% by weight and 99% by weight. , Particularly preferably between 60 wt .-% and 95 wt .-%, each based on the total weight of the respective mixture containing (a) or (b) and in each case the solvent! (F).
• Compounds (b) and, if appropriate, (c) the solvent (f) is removed from the reaction product. This can be done by different well-known methods, for example by drying or pouring off the excess solvent and subsequent drying. The drying is preferably carried out at pressures between 0.01 mbar and 1 bar and temperatures between -20 0 C and 6O 0 C for a duration of usually between 0.5 hours and 10 hours. Likewise, a freeze-drying can be used to remove the solvent.
• the surface tension should be as low as possible - therefore hydrocarbons and (partially) halogenated hydrocarbons are preferred solvents; 2) to avoid shrinkage under the drying conditions (preferably -20 to 60 ° C), the solvent should plasticize the polymer network as slightly as possible, ie, form a "precipitant" for the polymer, since such fluids are obviously unsuitable for synthesis the polyurethane network of the isocyanate and the isocyanate-reactive compound, it is advantageous to first make the network in a fluid swelling the network and then exchange this for a fluid with low swelling capacity.
• the solvent (T) is removed, preferably by drying, during which a pressure is selected which is less than the critical pressure during drying of the solvent and a temperature which is less than the critical temperature of the solvent used.
• the reaction of the isocyanates (a) with the isocyanate-reactive compounds (b) and Kettenverinrungsmittel ⁇ (c) can be carried out at conventional Ke ⁇ ngan, preferably at a ratio less than 1010.
• the index is defined by the ratio of the total isocyanate groups used in the implementation of the compo - ⁇ ente (a) to the isocyanate-reactive groups, ie the active hydrogens, components (b) and (c).
• an isocyanate group of component (a) has an active hydrogen atom, i. an isocyanate-reactive function, components (b) and (c).
• more isocyanate groups exist than OH groups.
• the reaction of the isocyanates with the isocyanate-reactive group and optionally chain extenders and / or crosslinking agents (c) at an index between 950 and 1050 by.
• thermoplastic polyurethanes can be prepared by reacting (a) isocyanates with (b) isocyanate-reactive compounds having a molecular weight of 500 to 10,000 and optionally (c) chain extenders having a molecular weight of 50 to 499, optionally in the presence of (d) catalysts and / or (e) customary excipients.
• MDI 1,2-diphenylethane-diisocyanate and / or phenyl-diisocyanate
• TDI 2,6-Toluylendiis ⁇ cyanat
• diphenylmethane diisocyanate 3.3 Dimethyl-diphenyl-diisocyanate, 1,2-diphenylethane-diisocyanate and / or phenyl-diisocyanate, tri-, tetra-, penta-, hexa-, hepta- and / or octamethylene-diisocyanate, 2-methylpentamethylene-diisocyanate-1, 5, 2-ethyl-butylene-diisocyanate-1, 4, pentamethylene diisocyanate-1, 5, butylene-diisocyanate-1,4,4-isocyanato-3,3,5-trimethyl-5-is
• trifunctional and higher-functional alcohols isocyanates having a functionality of at least 3, the trifunctional isocyanates obtainable by trimerization of TDI and / or PPDI, especially the isocyanate obtainable from TDI by reaction with trifunctional alcohols.
• isocyanate-reactive compounds (b) it is also possible, in addition to the compounds described at the outset, to use other compounds generally known for this purpose, for example polyesterols, polyetherols and / or polycarbonatediols, which are usually also included under the term "polyols" are, with molecular weights of 500 to 12000 g / mol, preferably 600 to 6000, in particular 800 to 4000, and preferably an average functionality of 1, 8 to 5. Preference is given only to use the inventive isocyanate-reactive compounds gene.
• Kettenverlä ⁇ gerungs- and / or crosslinking agent (c) may be used generally known aliphatic, araliphatic, aromatic and / or cycloaliphatic compounds having a molecular weight of 50 to 499 and a functionality of 2 to 10, for example aliphatic, cycloaliphatic and / or araliphatic Diols having 2 to 14, preferably 4 to 10 carbon atoms, such as Ethyle ⁇ glykol, propanediol-1, 3, decane-1, 10, o-, m-, p-dihydroxycyclohexane, diethylene glycol, dipropylene glycol and preferably butanediol-1, 4th , Hexanediol-1, 6 and bis- (2-hydroxy-ethyl) -hydroquinone, triols, such as 1, 2,4-, 1,3,5-trihydroxy-cyclohexane, glycerol and trimethylolpropane
• crosslinkers Provided for producing the polyurethanes chain extenders, crosslinkers or mixtures thereof are employed, they are advantageously present in an amount of from 0 to 30 wt .-%, pre- preferably 1 to 30 wt .-% r based on the weight of the used total isocyanate reactive compounds (b) and (c) are used.
• Groups of constituent components (b) and (c), especially the hydroxyl groups and / or amino groups, are the known and conventional tertiary amines known in the art, e.g. Triethylamine, dimethylcyclohexylamine, N-methylmorpho !, N, N'-dimethylpiperazine, 2- (dimethylaminoethoxy) ethanol, diazabicyc! O- (2,2,2) octane and the like, and in particular organic metal compounds such as titanic acid esters , Iron compounds such as Iron (III) acetylacetonate, zinc compounds, e.g.
• Zin ⁇ diacetat, Zinndioctoat, tin dilaurate or Zinndialkylsalze aliphatic carboxylic acids such as dibutyltin diacetate, dibutyltin dilaurate or the like.
• the isocyanate-reactive mixtures shown in Table 1 were reacted in a closed vessel at room temperature and a ratio of 1000 with the respective mixtures shown in Table 2 containing isocyanates.
• Boltorn® H20 polyester dendritic alcohol, M w ⁇ 2100 g / mol, polydispersity ⁇
• Boltorn® H30 Dendritic polyester alcohol, M w - 3500 g / mol, polydispersity ⁇
• Boltorn® H40 Dendritic polyester alcohol, M w - 5100 g / mol, polydispersity ⁇
• Basonat® TU 75E A polyfunctional TDl adduct having a weight fraction of 75% by weight in ethyl acetate, -13.3% NCO content
• the volume ratio of pentane to polyurethane gel was about 10: 1.
• the pentane was replaced by an equal amount of fresh pentane.
• the gel was removed and dried first for 3 days at atmospheric pressure, then for 2 days at a temperature of 60 0 C and a pressure of 100 mbar.
• Density measured by gas pycnometry (DIN 66137) Pore size measured by nitrogen sorption (DIN 66134) Specific surface measured according to BET (DIN 66131) Porosity measured by Hg intrusion (DIN 66133)
• the pore analysis in Table 3 shows that the gels prepared from the components listed in Tables 1 and 2 are nanoporous materials after subcritical drying.
• the comparison of the Hg intrusion and the nitrogen sorption shows that the pore content of less than 1 ⁇ m is greater than 95%.
• the average pore size of 50-150 nm makes these materials particularly advantageous for use as insulating material in thermal insulation. All materials showed high mechanical stability and low brittleness.

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• 2005
  • 2005-06-03 DE DE102005025970A patent/DE102005025970A1/de not_active Withdrawn
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