PRODUCTION OF POLYURETHANE PI-SIDAS FOAMS WITH REDUCED DENSITY The present invention refers to a friction or ai-1- the pi? I'di.C j? N of rigid foams and polyxurethane. PUP) of 5 density and with a low density thermal conductivity and its use as insulating material. The rigid foams of PUP 38 have been known for some time and have been used for fear of insulation against heat or cold, for example refrigeration equipment, in the sector of the building, for the storage of hot water. and in long-distance plumbing pipes. A review of the production and use of rigid foams, from PUR, can be found in the specific literature, for example in the monograph of J, H and Saunders} * C. Fpscb, 15 High Polymers Top Polymers), Vo3. XVI, Polyu ethanes, parts I and 2, int rs ience Publishers, 19Ó.2 and
-fr 1964, respec i amen e, or in K'uns tstof fhandbuch, Polyurethane, Vol. VII, C3 l-Hanser-V rl g, Munich, Vienna, anger, 2nd and 3rd edition, 19 > , 3983 and 1993, respectively, 20 The expansion agents used for the production of these foams have been up to date flua or lorohydrocarbons (FCHCs), especially trichlorof luoromethane. These FCHCs, due to their destructive effect on the soil layer of the soil, have to be replaced by materials that do not have this potential to damage the ozone layer (Potential of Desrucc in cié la capa of ozone, ODP) and that they have one sfer- or mumbrico greenhouse (Global Warming Potential, GUÍP - • »For these reasons, -they have proposed h? dro >" arbur os as agents of e ?? ans The future of the future, among the hydrocarbons, the pentane isomers play an outstanding role due to their relatively low boiling points, due to the fact that they are suitable as expansion agents for the production of rigid foams based on isocyanates The use of pentane derivatives has already been mentioned in the third edition of i 'uns ts to ff-Handbu h, ed S. Beci er and D «Braun, vol 7, ed 6. Oertel, Carl Hanser Verlag, Munich, Vienna, 1 < 3C > 3, for example on page 115 et seq. It has been shown that cyclopentane provides spuma of thermal conductivity less than n-pentane and isopentane, ÍEP-A-0 421 296) and therefore, cyclopentane and its mixtures with materials boiling below 35 ° C are the best types of halogen-free blowing agents known to the f. In the last two years, cyclopentane has been established in the European refining industry, but for reasons of cost and due to its slightly stronger expansion effect, n-pentapo -sopentane and other hydrocarbons are also used. low-boiling bitumens * as expanding agents, even though these provide lower conductivity values than those provided by cyclopentane-A when the use of these hydrocarbons, including 5-cyclopentane , provides foams that can be used very efficiently for insulation purposes, these products have disadvantages compared to the products expanded by FCHCs, paricularly in terms of density attainable at a compressive strength and adequate dimensional stability. The use of clopentane with carbon dioxide produced from water and isoc-3-nate provides free foam density of approximately 3C < kg / -t-3 in the laboratory in such a way that, for example, for refrigerators, a? 15 density of espu-ii3 of approx. 36 kg / mT, in order to produce foams having the compressive strength and dimensional stability required. This means an increase in the density of the foam, of IO4 compared to expanded rigid foams using 20 trielorofluoromethane and consequently high monthly production costs, resulting from the use of more material, in the manufacture, for example, of equipment of re rigeration. The partial vapor pressure of the cyclopentane at room temperature does not allow its proportion in the gas of cell 25 to exceed 38 * -, in such a way that the increase in the proportion of lopentane provides condensation of cyclopentane in the cells and was required to provide a distribution at a d.st. Ignition of the density of 13 foam. A possible foam density of foam density of expanded rigid foams using opentane cyclone by reducing the degree of overfilling always provides a lower compressive strength and dimensional stability, especially in long term tests, in such a way that it is not possible to produce usable foams of good quality in this way. EP-0 421 269 already proposed mixtures of low-boiling cysteine, cyclohexyl or low boiling point homogeneously miscible with cyclopentane and / or cyclohexane and having a boiling point lower than 35 ° C, selected from within 13 class consisting of alkanes or cycloalkanes containing 4 or less carbon atoms. A distribution of the density compared to the density of rigid foams blown only by cyclopentane does not occur however. EP-A-0 610 752 also employs mixtures of cycloalkane and linear or branched alkane expansion agents. The above-mentioned advantages have a low thermal conductivity and a good processing capacity in the machine, but a decrease in the density of free foams and consequently in the foam density of the resulting molded products has not been reached or described. It is an object of the present invention to produce rigid PUR espu-rs that do not have the above described ones whose resistance to compression and long-term dimensional stability are maintained particularly at low densities, such that when they are used , there is no need for high foam density which would be necessary in another way. We have found that this object is achieved, surprisingly, by the combination of a mixture of blowing agents consisting of id opentane with at least one homogenous compound and miscible with cyclopentane selected from the class consisting of alkanes and / or alkenes having 3 or 4 carbon atoms in the molecule and with the carbon dioxide produced from water and isacyanate and using higher molecular weight co-compounds having at least two reactive hydrogen atoms, polyesters containing aromatics and nor nitrogen. The invention therefore provides a process for the production of rigid foams of PUR with reduced density. by reaction of a) organic and / or organic polyisocyanates modified with b) at least one higher molecular weight compound having at least two reactive hydrogen atoms and, if desired, c) former chain tensors; 3310 molecular weight and / or reagents in the presence of d) expansion agents e) catalysts and, if desired, f) other auxiliaries and / or additives, which comprises the use, as a blowing agent * 'd), of a mixture of cyclopentane with at least one compound homogenously iscible with cyclopentane selected from the class consisting of alkanes / or lkenes having 3 or 4 a! carbon atoms in the molecule and with the carbon dioxide produced from water and isocyanate, and using, as compound ib) of molecular weight plus or minus at least two reactive hydrogen atoms, paters containing aromatics and nitrogen. The invention also provides the use, as insulation material, of rigid foams of PUR produced in this form. By use, in the component ib) of aromatic and nitrogen-containing olieters and by the use of the blowing agent mixture described, it is possible, surprisingly, to achieve a considerable distribution of the density of the free puma and consequently the foam density of the remaining molded products or molded articles without the described disadvantages of a compressive strength and a lower temperature stability., especially in long-term tests. It is known that the chemical structure of polyols influences the properties of foam. Different initial molecules and different molecular weights of the resulting polyols provide particular properties after the reaction with isocyanate, including the compressive strength and dimensional stability of rigid foams. It was expected, however, that the change of the paliol component could achieve a decrease in the foam density of the molded products which is + or would not result in a decrease in the physical and mechanical properties at the densities. Expansion agents having higher vapor pressures provide lower foam densities, but an undesirable result of this is that some properties, for example, compressive strength, are affected. As component (b), polyethers containing aromatics and nitrogen are employed, if desired in association with other higher molecular weight compounds having at least two reactive hydrogen atoms. The polyethers containing aromatics and nitrogen are especially the pol 3 ethers whose preparation is based on aromatic di amines on substitution N, v-y- and W, f "-di to which, as for example * 2,3- , 3,4-, 2,4- and 2, -tol i lend i 3mi na and 4,4'-, 2,4'- and 2,2'- d ia inodi fepi lmefc3 fi, poliamina de pol i fem Imeta not or in mixtures of the mentioned compounds. It is advantageous to employ initiated polyethers using tolylene and / or polyacrylamide 5 and having a hydrophilic number of 300 to 600 mg KOH / g in a preferably from 5 to 25 by weight, in a specifically preferred manner, from 13 to 50% by weight, based on the total amount of the foam. The other higher molecular weight compounds having IO a3 minus two reactive hydrogen atoms and which may, if desired, be used in association with two polyethers containing arametics and nitrogen, are further described in addition to the invention. The proportion here between the polyethers containing omatons and / or nitrogens and those which are used according to the invention, based on the entire component (b) is at least 15 * / * by weight, preferably 30 to 5% by weight. The blowing agents according to the present invention are a mixture of cyclopentane with at least one compound homogeneously miscible with cyclopentane selected within the phase consisting of alkanes and / or alkenes having 3 or 4 carbon atoms in the molecule and water. Compounds homogeneously cyclosable with cyclopentane selected from the class consisting of alkanes / or alkenes having 3 or 4 carbon atoms in the molecule are preferably propane, n-bu l, 3t? U, is but-an , ci - >; -2-bu te or \ / o trans-Z-buterm, These components can be used individu lmen e > Good ei. mixtures between them. It is advantageous to use inexpensive industrially available mixtures of propane and butane. Especially preferred are n-butane and isobutyl. It is also possible, however, to use mixtures of butane and butene. Cyclopentane is preferably used in an amount of
0. 1 to 10 * 4 by weight, par- ticularly from 3 to 7 * 4 by weight, and the alkanes / or alkenes having 3 or 4 carbon atoms in the molecule are used p r & 0.1 to 6 * 4 by weight, paricularly from 0.1 to 6 * 4 by weight, based in each case on I s. entire amount of foam, In addition to the described blowing agent components, water is used in chemical expansion agents. The water reacts with the isocyanate groups of component a) to provide carbon dioxide. The water is preferably added to the < b) in an amount of 0.5 to 5 * 4 by weight, based on the weight of component ib). The water may also be added together with the other blowing agents to be used in accordance with the invention. The mixture of blowing agents according to the present invention can be prepared separately by pre-mixing the components-in-ion. The expansion agent m-_ 13 was removed from the conventional polyol component of the described polyol component. You can also enter the hydro arbu composers? or indi idually in the product stream, preferably in the polyol component, immediately before passing to the mixing head for mixing the polyol component with the isocyanate component, It can also be introduced into a head of Mixed of multiple components specific. The hydrocarbons are handled in a known manner using pumps, ignition devices and storage containers. The rigid foams of PUP are produced in a known manner per se, by reacting: a) organic polyisocyanates and organic u'u modified with b) at least one compound of molecular weight m < -? sao that has at least two reactive hydrogen atoms and, if desired, c) Ba chain extenders or molecular weight and / or crosslinkers in the presence of d) Expansion agents e) Catalysts and, if desired , f) other auxiliaries and / or additives. For the production of the rigid foams of FUR through the novel process, was it heard? > ZUB the expansion me-rela t-ale specifies ib, 1 and --- je-M ----- of 1 »- '= - μolif' ^? As described above that cardie-er-arüHln .? and nitrogen, of the for > n3 i vo-- > UÍIU idus per se, which are described individually below; a) Suitable modified organic and / or organic isocyanates are aliphatic, cycloaliphatic, aral-phthalic and preferably roman cyclohexane poly-fune isocyanates known per se as described, for example, in the EP-0 421 268. Column 4, line 49, to column 6, row 22) or in EP-A-0 719 S07"column 2, line 53, to column 4, row 21). Materials which have proven their utility are mixtures of isomer diisocyanate di methane or raw pDI having an isomer content of diphenylmethane diisocyanate of 33 to 55 * 4 by weight and ezclas of isocyanate and paliate containing urethane groups and in difeni 3 me 3 diisocyanate not having an NCO content of 15 to 33 * 4 by weight, b) Compounds having at least two hydrogen atoms which react with isocyanates according to the invention are the described polyethers above that contain aromatics and nitrogen. Thus, other compounds having at least two hydrogen atoms that react with isocyanates can be used, the suitable compounds being those having two or more groups rs-c ti-ü = -, in 1 -i molecule, 3 * 3leo: 1 waves within the ciase that you consider > Je OH, SH, NH, H2 and CH 5 gone. It is convenient to use compounds having functionality from two to eight, preferably from 2 to 6, and an average molecular weight from 300 to 8000, preferably from 400 to 4000. Examples of materials that have proven to be useful are polyamides of polyester and / or preferably polyols selected from the group consisting of polyether polyols, polyester polyolspolyethylether, polyether-t-i, polyacetals containing hydrophilic groups, aliphatic polycarbonates containing hydroxyl groups and mixtures of at least two of the mentioned paliols. Polyester pallets and / or polyether palols are preferably used. The hydroxyl number of the polyhydroxy compounds herein is generally from 100 to B50 and from 200 to 600. Further details as to the compounds that may be employed can be seen as for example, in EP-A-0 421 269 (column 6). , line 23, to column 10, row 5) or EP-A-0 -1 807 (cell 4, row 23, to column 7, row 55). c) PUP rigid foams can be produced with or without the additional use of e: chain tensioners and / or reticulators. The addition of former chain tensioners, eiculators, or, if desired, mixing, of these may be useful, however, in modifying the properties eic, for example the rigidity. I know; Chain Tenders / > z > re 3 > The carriers used are diols and / or triols that have lower molecular weights than
400, preferably 60 to 300, Aliphatic, cycloaliphenyl and / or phallic diols having 2 to 14, preferably 4 to 10, carbon atoms are preferred. Additional details regarding these and other compounds that can be used can be found, for example in the document
EP-A-421 269 (column 1, rows 6 to 48 i) If chain tensioners, binders or densities are used to produce the rigid foams, they are conveniently used in an amount of 0 to 20 *. by weight, preferably from 2 to 8 * 4 by weight, based on the weight of the active component (b) d) In accordance with the invention, the mixture of blowing agents described above is used for the production of the rigid foams of PUP. e) The catalysts (e) used for the production of rigid foams of PUR are specific compounds which greatly accelerate the reaction of the compounds of component (b) containing 4 reactive hydrogen atoms, particularly hydro groups. ilo and, if they are used, (c), with organic polymers, modified or unmodified (a). By means of suitable catalysts (s), the isocyanate groups can also be induced to react with each other, however, providing, in addition to the isocyanate adducts (a) with the compounds (b) having groups with active hydrogen, preferably The catalysts are therefore particularly materials that accelerate the reactions of the isocyanates, particularly the formation of urethanes, ureas and isocyanates.The catalysts are therefore particularly materials that accelerate the reactions of the isocyanates, The formation of urethanes, ureas and isocyanurates is particularly preferred The preferred compounds for this purpose are tertiary amines, tin compounds and bismuth compounds, alkali metal carboxylates, carbaxylates of alkaline earth metals, quaternary ammonium salts, hexahydrothriazines, and tris (dialkyl laminomethyl 1) phenols. Additional details can be found in for example, for example, in EP-A-0 719 807 (column 9, rows 5 to 56). f) Auxiliaries and / or additives (can also be incorporated into the reaction mixture to produce the rigid foams of PUR) Examples of these are surfactants, foam stabilizers, cell regulators, * p - rorretardants, re] Odors, dyes, pigments, agents to avoid the hydrolysis of substances with vfp or fungic or ba er IO? L «ca. Additional details er as regards the compounds that can be used can be found, 5 for example , in EP-A-0 421 269 (column 12, line 55, column 14, ren 16) or in EP-A-0 719 807 (column 9, line 58, column 13, line 17) - Additional details regarding the initial materials IO mentioned above and other conventional starting materials can be found in the technical literature, for example, in the monograph by TH Saunders and C.C. psch, High Polymers. ), vol-, XVI, Polyurethanes, parts 1 and 2, T nterse jence Publishers, ic ? 62 and 15 1964 respectively, or in \ unststoffhandbuch, Polyurethane, Vsl. VII, Carl-H3nsei-Verlag, Munich, Vienna, 1st. -? 2nd and 3rd edition, 1966, 83 and 1993 respectively. For the production of the PUP rigid foams, the modified organic and / or organic polyisocyanates, 20 higher molecular weight compounds having 3.1 minus two reactive hydrogen atoms (b) and, if desired, extenders of ca.d &na and / or cross-linkers (c) react in amounts calculated in such a way that the ratio of equivalence between NCOs of the polyolions (a) and 25 the total of the reactive hydrogen atoms of the components ib) and, if employs, c) is of .85 to,,? 5 5 3 3, of p re ferenc ia on of 1.0 3 1.3 1 1 and par ularly of 1.1 to 1.2. If the rigid foams b3 = ad ad3 = in isorianate contain, less to a certain extent, isocyanate groups in its structure, a ratio between the NCO groups in the polyisocyanates (a) and the total reactive hydrogen atoms in component lb) and, if used, to 60; 1, preferably from 3 to 8: 1, is used habitually. Rigid foams are profitably produced by means of the non-typical process, for example using the high pressure or low pressure method in open or closed molds, for example metal molds. It has been found especially advantageous to operate the two-component process and combine the forcible components (b), (di, (e) and, if used, íc) and (f) in the component Í) and use the organic polyisocyanates and / or modified polyisocyanates (a) or more of the aforementioned polyisocyanates and, if desired, blowing agents (di as component (B), often called the isocyanate component. The initial components are mixed at a temperature of between 15 and 80 ° C, preferably 20 to 30 ° C, and are introduced in an open mold or, if desired, under high pressure, in a mold that can, if desired, be controlled The temperature of the mold is conveniently between 20 and 50 ° C, preferably between 30 and 60 ° C, and par- ticularly between 45 and 50 ° C. The rigid foam of PUR produced by the use in accordance with the present invention of polyesters containing aromatics and nitrogen , co or higher molecular weight compounds having at least two reactive hydrogen atoms, combined with the mixture of blowing agents described, preferably have densities of 25 to 40 tg / m3. The compression resistances determined by these reduced densities correspond to those of the rigid foams of the prior art having higher densities. Stability d i ens canvas, esp < ^ > . Long-term densities also show no disadvantages compared to conventional rigid espu-n-ts with high month densities. The products are preferably used as insulating material in the construction and refrigeration equipment sectors. They are used in particular as intermediate layers for sandwich components or for the filling of refrigerator and freezer compartments. The invention is further described in the following working examples. Comparative Examples 1-3 and Working Example 4-7s The formulations provided in the following table were converted to rigid PUR espu -ss. The characteristic properties, how? For example, the free foam density, the molding diameter, the compressive strength and the dye sterility were determined afterwards. The compressive strength was measured in accordance with DIN 53421 in a direction perpendicular to the direction of foaming. . The long-term dimensional stability was determined in tubes of dimension 5 5; 5 cm that had been subjected to a constant load of 0.05 N / m-í-2 at a temperature of 22 +/- 2 * C for 30 days. The load went to li a a in the direction of foam formation. The results of the tests appear in the lower part of the tab3a and show the good level of physical and mechanical properties of the foams having a lower density compared to the foams of the prior art. Table Example 1 (Comparative Example 1) COMPONENT A OH index (mg KOH / g 1 i Polyether alcohol 490 pg 60 based on sucrose / propylene oxide polyethylene alcohol 530 pep 1.5 ba ao in biofo1 / diet nola Inactivated propylene Polyether alcohol 390 pep - based on tol i lendiamine / ethylene oxide / propylene oxide Polyether alcohol 380 pep - based on di phene Imet n-diamine / oxide of e-tilene / ox of prop i ieno P oliet i lengl icol 250 pep 7
Pepper 2 silicone foam stabilizer BS467 (Goldschmidti Dimetilcilcohexilamina pep 2.5 Water pep 2
Cyclopentans pep 11.5 n-butane pep -
Isobutane pep - cis / trans - 2 - butene pep - trans / trans - 2 - butene pep - COMPONENT B Crude product MDI, NCO pep content 31.5 * 4 by weight Foam density 1 ix x / in. - j 3 Density Molding g / m3 R.Consistent to compression N / mm2 0.13 Dimensional stability% 1
Axis p1o 4 (Example (Example (Example CompaCompaCompar t i vo) rat i o) ra t i o)
COMPONENT A
Polyether alcohol 60 30 50 based on sucrose / propylene oxide 15 15 15 pallather alcohol based on bisphenol A / diethanolamine / propylene oxide Polyether alcohol 30 30 based on tol i lend iami na. / propylene oxide / propylene oxide Polyether alcohol - - - based on dipheni I ethane dia / ethylene oxide / polyethylene oxide Polymethyl glycol 7 7 7
Foam stabilizer 2 2 2 silicone B8467 (Goldschmidt) Dimethylcyclohexylamine 2.5 2.5 2.5
Water 2 2 2
Cyclopentane 9.2 l.5 9.2 n-butane - - 2.3
Isobu or 2.3 - - cis / trans-2-butene - - - trans / rans-2-butene - - -
COMPONENT B Gross product MDI, NCO 150 Í40 140 content 31.5 * 4 by weight Density foam 1 ibre 28.0 3 .0 27.5
Molding density 33.5 36.0 33.0
Resistance to compression 0.10 0.13 0.3.3
Stability dimension l 15 14 8
Example 5 (E je p lo (Example I e (E p p o r Comp Camp - ra t i o) raí i vo i ra i vo)
COMPONENT A
Polyether alcohol 34.5 34.5 34.5 based on sucrose / propylene oxide Polyether alcohol - bisphenol-based A / d iethanolamine / propylene oxide Polyether alcohol 20 based on tol-lendiamine / ethylene oxide / polypropylene alcohol Polyether alcohol 20 40 based on difeni I ethan diamine / ethylene oxide / propylene oxide Polyethylene glycol 7 Foam stabilizer 2 silicone B8467 (Goldschmidt i Dimeti lc i lcohex i lamina 3 3 3 Water 2 2 2 Cyclopentane 9.2 9.2 9.2 n-butane - - -
Isobutane - - 2.3 c is / trans-2-butene 2.3 - - trans / trans-2-butene - 2.3 - COMPONENT BP bryduct or MDI, NCO 130 130 125 lO content 31.5 * 4 by weight Density foam 1 ibre 27.5 27.0 27.0
Molding density 33.0 33.0 33.0
Resistance to compression 0.13 0.13 0.13
Dimensional stability 8 9 8
pep = parts by weight
> 0