CA2246007A1 - Production of fine-celled rigid foams based on isocyanate - Google Patents
Production of fine-celled rigid foams based on isocyanate Download PDFInfo
- Publication number
- CA2246007A1 CA2246007A1 CA002246007A CA2246007A CA2246007A1 CA 2246007 A1 CA2246007 A1 CA 2246007A1 CA 002246007 A CA002246007 A CA 002246007A CA 2246007 A CA2246007 A CA 2246007A CA 2246007 A1 CA2246007 A1 CA 2246007A1
- Authority
- CA
- Canada
- Prior art keywords
- mold
- pressure
- bar
- loaded
- components
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Abandoned
Links
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
- B29C44/00—Shaping by internal pressure generated in the material, e.g. swelling or foaming ; Producing porous or cellular expanded plastics articles
- B29C44/02—Shaping by internal pressure generated in the material, e.g. swelling or foaming ; Producing porous or cellular expanded plastics articles for articles of definite length, i.e. discrete articles
- B29C44/10—Applying counter-pressure during expanding
- B29C44/105—Applying counter-pressure during expanding the counterpressure being exerted by a fluid
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29K—INDEXING SCHEME ASSOCIATED WITH SUBCLASSES B29B, B29C OR B29D, RELATING TO MOULDING MATERIALS OR TO MATERIALS FOR MOULDS, REINFORCEMENTS, FILLERS OR PREFORMED PARTS, e.g. INSERTS
- B29K2075/00—Use of PU, i.e. polyureas or polyurethanes or derivatives thereof, as moulding material
Landscapes
- Polyurethanes Or Polyureas (AREA)
- Manufacture Of Porous Articles, And Recovery And Treatment Of Waste Products (AREA)
Abstract
Fine-celled rigid polyurethane foams are produced by reacting polyisocyanates with compounds containing at least two reactive hydrogen atoms in closed molds, wherein a) the reaction components are loaded with gas under pressure before being introduced into the mold, b) the mold is pressurized before, during or after introduction of the reaction mixture, c) depressurization takes place in the mold after introduction of the reaction mixture into the mold and before the rigid foam has set.
Description
' BASF Aktiengesellschaft 970100 O.Z. 0050/48367 -Production of fine-celled rigid foams based on isocyanate 5 The present invention relates to a process for producing fine-celled rigid foams based on isocyanate and also an apparatus for carrying out the process.
The production of rigid foams based on isocyanate and the use of 10 such products as thermal insulation material has been known for a long time and is widely described in the literature. As chemical structures which are formed from the polyisocyanates, the foams can comprise polyurethanes, polyureas, polyisocyanurates and also further isocyanate adducts such as allophanates, biurets, 15 carbodiimides and their isocyanate adducts, oxazolidones, polyimides, polyamides and others. In general, these isocyanate adducts are summarized under the term polyurethanes since the polyurethanes are the most important and most widespread group of materials among the polyisocyanate adducts. Rigid foams based on 20 isocyanate are therefore usually referred to as rigid polyurethane (PUR) foams. In the case of a significant proportion of isocyanurate structures, these foams are also known as polyurethane/polyisocyanurate (PUR/PIR) foams, or just PIR foams.
The production of such foams is described, for example, in the 25 Kunststoff-Handbuch, Volume VII, Polyurethanes, Carl-Hanser-Verlag, Munich, 1st Edition 1966, 2nd Edition 1983 and 3rd Edition 1993.
These foams usually have a cell diameter of over 200 ~m. In the 30 case of closed-celled foams, the thermal conductivity is too high as a result of this large cell diameter. In the case of open-celled rigid PUR foams, as are used, in particular, as core material for vacuum insulation units, the demands placed on the vacuum are very high in order to obtain the low thermal 35 conductivities required. The greater the cell diameter of the foam, the more difficult it is to generate a stable vacuum in the foam. In addition, open-celled foams having relatively large cells have a higher thermal conductivity at the same vacuum.
40 There have therefore been many attempts to reduce the size of the cells in the foams by physicochemical means. Thus, EP-A-351 614 and DE-A-41 43 148 propose using perfluoro compounds as blowing agents. However, such blowing agents are very expensive.
Apart from influencing the cell size by physicochemical means, for example by selection of the blowing agents, it is also possible to reduce the cell size independently of the formulation CA 02246007 1998-09-2~
BASF Aktiengesellschaf t 970100 O. Z . 0050/48367 by means of the foaming conditions. Thus, it is known that a rigid PUR foam is usually finer-celled when foamed by machine than when the components are mixed in a simple stirred vessel and subsequently foamed.
It is known from the Kunststoff-Handbuch, Volume VII, Polyurethane, 2nd Edition 1966, pages 470-473 that the cell size and the number of nuclei can be changed by varying the pressure in the mixing head. However, the change effected here is 10 significant at very large cell sizes above 300 ,um.
US-A-5,472,990, EP-A-378 243 and EP-A-686 467 describe apparatuses for gas loading and formation of nuclei. However, the 15 loading with, for example, carbon dioxide described there leads only to small changes in the cell size.
It is an object of the present invention to reduce the cell size of rigid foams based on isocyanate without special changes in 20 formulation being necessary and without additional process steps having to be carried out after foam production.
We have found that this object is achieved by specific pressure conditions during foaming.
The present invention accordingly provides a process for producing fine-celled rigid foams based on isocyanate by reacting polyisocyanates with compounds containing at least two reactive hydrogen atoms in the presence of blowing agents, catalysts and, 30 if desired, further auxiliaries and/or additives in closed molds, wherein a) the reaction components are loaded with a gas before being introduced into the mold, b) the mold is pressurized with gas before or during introduction of the reaction components, 40 c) depressurization takes place in the mold after introduction of the reaction mixture into the mold and before the foam has set.
The reaction components are loaded with the gas at pressures of 45 from 0.1 to 26 bar.
- BASF Aktiengesellschaft 970100 O.Z. 0050/48367 The mold is pressurized to a pressure of from 0.1 bar to 25 bar, in particular from 0.5 bar to 15 bar. The mold is depressurized to from 0.1 bar to 10 bar, preferably from 0.9 bar to 2 bar, with the depressurization being carried out during the time from 5 0 seconds after introduction of the reaction mixture into the mold to the fiber time minus one second.
The pressure is generated by means of substances which are gaseous at room temperature and are inert toward the reaction 10 components, for example air, nigrogen, carbon dioxide, dinitrogen oxide, argon, helium or neon, in particular carbon dioxde.
To carry out the process of the present invention, it is 15 advantageous to likewise keep the reservoir for the polyurethane components as well as the product lines to the mixing head under pressure. The pressure here should be from 0 bar to 26 bar, in particular from 0.5 bar to 15 bar.
20 The pressure in the mold is here always less than the pressure at which the reaction components are loaded with the gas.
The process of the present invention can be employed for producing all rigid foams based on isocyanate which are produced 25 in molds, but particularly in the production of polyurethane (PUR) and polyurethane-polyisocyanurate (PIR) foam.
The following details may be provided in respect of the starting components used for such foams:
Suitable organic polyisocyanates are the aliphatic, cycloaliphatic, araliphatic and preferably aromatic polyfunctional isocyanates known per se, as are described, for 35 example, in EP-A-0 421 269 (column 4, line 49, to column 6, line 22) or in EP-A-0 719 807 (column 2, line 53, to column 4, line 21).
Polyisocyanates which have been found to be particularly useful 40 are diphenylmethane diisocyanate isomer mixtures (crude MDI) having a diphenylmethane diisocyanate isomer content of from 33 to 55 % by mass and polyisocyanate mixtures based on diphenylmethane diisocyanate which contain urethane groups and have an NCO content of from 15 to 33.6 % by mass.
- BASF Aktiengesellschaft 970100 O.Z. 0050/48367 AS compounds containing at least two hydrogen atoms which are reactive toward isocyanates, use is made according to the present invention of the above-described nitrogen-containing polyethers containing aromatic rings. In addition, further compounds 5 containing at least two hydrogen atoms which are reactive toward isocyanates can be employed. For this purpose, it is possible to use compounds which have two or more reactive groups selected from among OH groups, SH groups, NH groups, NH2 groups and CH acid groups, in particular OH groups, in the molecule.
Use is advantageously made of those having a functionality of from 2 to 8, preferably from 2 to 6, and a mean molecular weight of from 300 to 8000, preferably from 400 to 4000. Examples of compounds which have been found to be useful are 15 polyetherpolyamines and/or preferably polyols selected from the group consisting of polyether polyols, polyester polyols, polythioether polyols, polyesteramides, hydroxyl-containing polyacetals and hydroxyl-containing aliphatic polycarbonates or mixtures of at least two of the polyols mentioned. Preference is 20 given to using polyester polyols and/or polyether polyols. The hydroxyl number of these polyhydroxyl compounds is usually from 100 to 850 and preferably from 200 to 600. Further details regarding the compounds which can be used may be found, for example, in EP-A-0 421 269 (column 6, line 23 to column 10, line 25 5) or EP-A-0 719 807 (column 4, line 23 to column 7, line 55).
The rigid PUR foams can be produced with or without the concomitant use of chain extenders and/or crosslinkers. To modify 30 the mechanical properties, eg. the hardness, the addition of chain extenders, crosslinkers or, if desired, mixtures thereof can prove to be advantageous. Chain extenders and/or crosslinkers used are usually diols and/or triols having molecular weights of less than 400, preferably from 60 to 300. Preference is given to 35 using aliphatic, cycloaliphatic and/or araliphatic diols having from 2 to 14, preferably from 2 to 10, carbon atoms. Further details regarding these and further compounds which can be used may be found, for example, in EP-A-0 421 269 (column 10, lines 6 to 48).
If chain extenders, crosslinkers or mixtures thereof are employed for producing the rigid foams, they are advantageously used in an amount of from 0 to 20 % by weight, preferably from 2 to 8 % by weight, based on the weight of the compounds containing at least 45 two reactive hydrogen atoms.
CA 02246007 1998-09-2~
- BASF Aktiengesellschaft 970100 O.Z. 0050/48367 Catalysts used for producing the rigid PUR foams are, in particular, compounds which strongly accelerate the reaction of the compounds containing reactive hydrogen atoms, in particular hydroxyl groups, with the organic, modified or unmodified 5 polyisocyanates. However, the isocyanate groups can also be reacted with one another by means of suitable catalysts, preferably forming isocyanurate structures in addition to the adducts of isocyanates and the compounds containing hydrogen-active groups.
Catalysts used are thus, in particular, those substances which accelerate the reactions of the isocyanates, in particular urethane, urea and isocyanurate formation.
For this purpose, preference is given to tertiary amines, tin and bismuth compounds, alkali metal carboxylates and alkaline earth metal carboxylates, quaternary ammonium salts, s-hexahydrotriazines and tris(dialkylaminomethyl)phenols.
Further details regarding catalysts which can be used may be found, for example, in EP-A-0 719 807 (column 9, lines 5 to 56).
If desired, auxiliaries and/or additives can also be incorporated 25 into the reaction mixture for producing the rigid PUR foams.
Examples which may be mentioned are surface-active substances, foam stabilizers, cell regulators, flame retardants, fillers, dyes, pigments, hydrolysis inhibitors, fungistatic and bacteriostatic substances. Further details regarding the 30 compounds which can be used may be found, for example, in EP-A-0 421 269 (column 12, line 55 to column 14, line 25) or EP-A-0 719 807 (column 9, line 58 to column 13, line 17).
Blowing agents which can, if desired, be used for producing the 35 foams of the present invention include preferably water which reacts with isocyanate groups to form carbon dioxide. The amounts of water which are advantageously used are from 0.1 to 8 parts by weight, preferably from 1.5 to 5.0 parts by weight and in particular from 2.5 to 3.5 parts by weight, based on 100 parts by 40 weight of the compounds containing at least 2 active hydrogen atoms.
In admixture with water, it is also possible to use physically 45 acting blowing agents. Suitable physically acting blowing agents are liquids which are inert toward the organic, modified or unmodified polyisocyanates and have boiling points below 100~C, preferably below 50OC, in particular from -50~C to 30~C, at CA 02246007 1998-09-2~
BA~F Aktiengesellschaft 970100 O.Z. 0050/48367 atmospheric pressure so that they vaporize under the action of the exothermic polyaddition reaction. Examples of such preferred liquids are alkanes such as heptane, hexane, n- and iso-pentane, preferably industrial mixtures of n- and iso-pentanes, n- and 5 iso-butane and propane, cycloalkanes such as cyclopentane and/or cyclohexane, ethers such as furan, dimethyl ether and diethyl ether, ketones such as acetone and methyl ethyl ketone, alkyl carboxylates such as methyl formate, dimethyl oxalate and ethyl acetate and halogenated hydrocarbons such as methylene chloride, 10 dichloromonofluoromethane, difluoromethane, trifluoromethane, difluoroethane, tetrafluoroethane, chlorodifluoroethanes, 1,1-dichloro-2,2,2-trifluoroethane, 2,2-dichloro-2-fluoroethane and heptafluoropropane. Mixtures of these low-boiling liquids with one another and/or with other substituted or unsubstituted 15 hydrocarbons can also be used. Other suitable blowing agents are organic carboxylic acids such as formic acid, acetic acid, oxalic acid, ricinoleic acid and carboxyl-containing compounds.
Preference is given to using water, chlorodifluoromethane, 20 chlorodifluoroethanes, dichlorofluoroethanes, pentane mixtures, cyclohexane and mixtures of at least two of these, eg. mixtures of water and cyclohexane, mixtures of chlorodifluoromethane and l-chloro-2,2-difluoroethane and, if desired, water.
The amount of physically acting blowing agents required in addition to water can be readily determined as a function of the desired foam density and is from about 0 to 25 parts by weight, preferably from 0 to 15 parts by weight, per 100 parts by weight 30 of the compounds containing at least two active hydrogen atoms.
It may be advantageous to mix the modified or unmodified polyisocyanates with the inert physically acting blowing agents and thereby reduce the viscosity.
35 However, the starting materials except for the polyisocyanates are usually combined to form the polyol components.
To produce the foams of the present invention, the isocyanate components and the polyol components are combined and then 40 allowed to foam.
As mixing unit, preference is given to using the known high-pressure mixing heads by the high-pressure process which is described, for example, in Kunststoff-Handbuch, Volume VII, 45 Polyurethane, edited by G. Oertel im Carl-Hanser-Verlag, Munich, Vienna 1993, page 143 ff.
CA 02246007 1998-09-2~
BASF Aktiengesellschaft 970100 O.Z. 0050/48367 However, it is also possible to use the low-pressure mixing heads described in the same reference.
The process of the present invention enables the cell sizes of 5 all rigid foams based on isocyanate to be reduced, both the open-celled and the closed-celled types.
The process of the present invention is particularly advantageous 10 in the production of open-celled foams which can be used as core material for vacuum insulation units.
The invention is illustrated by the following examples.
15 Formulation A:
Polyetherol 1: 30 % of a tolylenediamine-initiated polyether polyol derived from ethylene oxide and propylene oxide and having a hydroxyl number of 400 mg KOH/g Polyetherol 2: 20 % of a polyetherol based on bisphenol A, diethanolamine, formaldehyde and propylene oxide and having a hydroxyl number of 530 mg KOH/g Polyetherol 3: 23 % of a polyetherol based on sucrose, glycerol and propylene oxide and having a hydroxyl number of 490 mg KOH/g Polyetherol 4: 5 % of a polyetherol based on propylene glycol and propylene oxide and having a hydroxyl number of 250 mg KOH/g 30 Polyetherol 5: 15 % of an amine-initiated polyetherol prepared using ethylene oxide and propylene oxide and having a hydroxyl number of 115 mg KOH/g Stabilizer: 3 % of silicone stabilizer Tegostab~ B8465 from Th. Goldschmidt Catalysts: 0.5 % of dimethylcyclohexylamine 0.7 % of pentamethyldiethylenetriamine 0.7 % of Dabco~ TMR3 from Air Products 40 Blowing agents:2 % of water 13 % of cyclopentane Polyisocyanate:Crude MDI Lupranat~M20A (NCO content 31.5 % by weight), BASF AG
Index: 135 CA 02246007 1998-09-2~
BASF Aktiengesellschaft 970100 O.Z. 0050/48367 Formulation B:
Polyetherol 1: 20 % of a polyetherol based on ethylenediamine and propylene oxide and having a hydroxyl number of 470 mg KOH/g Polyetherol 2: 40 % of a polyetherol based on sucrose, glycerol and propylene oxide and having a hydroxyl number of 490 mg KOH/g ~0 Polyetherol 3: 30 % of a polyetherol based on trimethylolpropane and propylene oxide and having a hydroxyl number of 555 mg KOH/g Polyesterol 4: 10 % of a polyesterol comprising castor oil and glycerol and having a hydroxyl number of 360 mg KOH/g Stabilizers and cell openers:
3 % of Tegostab~ B 8919 from Th. Goldschmidt 1 % of Tegostab~ B 8863Z from Th. Goldschmidt 1 % of Fluorad~ FC-430 from 3M
Catalyst: 5 % of Dabco~ AN20 from Air Products Blowing agents:0.5 % of water 7 % of cyclopentane 4 % of perfluorohexane Polyisocyanate:Crude MDI Lupranat~ M20A
(NCO content 31.5 % by weight); BAS~ AG
Index: 130 Formulation C:
Polyetherol 1: 78.5 % of a polyetherol based on sucrose, glycerol and propylene oxide and having a hydroxyl number of 490 mg KOH/g Polyetherol 2: 15 % of a polyetherol based on propylene glycol and propylene oxide and having a hydroxyl number of 105 mg KOH/g ~ Catalyst: 2 % of dimethylcyclohexylamine Stabilizer: 2.5 % of Polyurax~ SR321 from Deutsche BP Chemie GmbH
Blowing agent: 2 % of water ~5 Polyisocyanate:Crude MDI Lupranat~ M20W
(NCO content 31.5 % by weight), BASF AG
BASF Aktiengesellschaft 970100 O.Z. 0050/48367 Index: 110 The systems displayed the following laboratory values (free-foamed) A B C
Cream time [s] 10 11 15 Fiber time [s] 51 65 50 10 Foam density 31 58 52 [kg/m3]
Foaming was carried out by means of a Puromat~ high-pressure 15 foaming machine from Elastogran GmbH.
A cylindrical foam mold having a diameter of 20 cm and a height of 5 cm was used.
20 The open cell content was determined in accordance with ASTM D 2856-87, method B, the foam density was determined in accordance with DIN 53420, the cell diameter was determined in accordance with ASTM D 3576-77, the thermal conductivity was determined in accordance with DIN 52616 in a Hesto-Lambdakontrol Examples 1 to 6 30 Foaming of formulation A
Foaming was carried out as described above. The pressureconditions and the results obtained are shown in Table 1.
o ~
~ ul ~' Table 1: Comparison of the results for formulation A
Prepressure = pressure on the containers, counterpressure = pressure on the mold Gas used: nitrogen O
ExamplePlt;pressu~eCounter-- D~ u~ FoamCell diameter CTC CTC Open cell Remarks pressure tion time density content [mW/mK] [mW/mK]
[bar] [bar] [s] [kg/m3] [~Im] after 1 dayaner 1 week [%]
O O 0 27.6 300 19.8 19.8 2.3 C~ i 1 (C) 2 5 3 18 26.1 155 18.3 18.6 6.2 according to the present invention ~.
The production of rigid foams based on isocyanate and the use of 10 such products as thermal insulation material has been known for a long time and is widely described in the literature. As chemical structures which are formed from the polyisocyanates, the foams can comprise polyurethanes, polyureas, polyisocyanurates and also further isocyanate adducts such as allophanates, biurets, 15 carbodiimides and their isocyanate adducts, oxazolidones, polyimides, polyamides and others. In general, these isocyanate adducts are summarized under the term polyurethanes since the polyurethanes are the most important and most widespread group of materials among the polyisocyanate adducts. Rigid foams based on 20 isocyanate are therefore usually referred to as rigid polyurethane (PUR) foams. In the case of a significant proportion of isocyanurate structures, these foams are also known as polyurethane/polyisocyanurate (PUR/PIR) foams, or just PIR foams.
The production of such foams is described, for example, in the 25 Kunststoff-Handbuch, Volume VII, Polyurethanes, Carl-Hanser-Verlag, Munich, 1st Edition 1966, 2nd Edition 1983 and 3rd Edition 1993.
These foams usually have a cell diameter of over 200 ~m. In the 30 case of closed-celled foams, the thermal conductivity is too high as a result of this large cell diameter. In the case of open-celled rigid PUR foams, as are used, in particular, as core material for vacuum insulation units, the demands placed on the vacuum are very high in order to obtain the low thermal 35 conductivities required. The greater the cell diameter of the foam, the more difficult it is to generate a stable vacuum in the foam. In addition, open-celled foams having relatively large cells have a higher thermal conductivity at the same vacuum.
40 There have therefore been many attempts to reduce the size of the cells in the foams by physicochemical means. Thus, EP-A-351 614 and DE-A-41 43 148 propose using perfluoro compounds as blowing agents. However, such blowing agents are very expensive.
Apart from influencing the cell size by physicochemical means, for example by selection of the blowing agents, it is also possible to reduce the cell size independently of the formulation CA 02246007 1998-09-2~
BASF Aktiengesellschaf t 970100 O. Z . 0050/48367 by means of the foaming conditions. Thus, it is known that a rigid PUR foam is usually finer-celled when foamed by machine than when the components are mixed in a simple stirred vessel and subsequently foamed.
It is known from the Kunststoff-Handbuch, Volume VII, Polyurethane, 2nd Edition 1966, pages 470-473 that the cell size and the number of nuclei can be changed by varying the pressure in the mixing head. However, the change effected here is 10 significant at very large cell sizes above 300 ,um.
US-A-5,472,990, EP-A-378 243 and EP-A-686 467 describe apparatuses for gas loading and formation of nuclei. However, the 15 loading with, for example, carbon dioxide described there leads only to small changes in the cell size.
It is an object of the present invention to reduce the cell size of rigid foams based on isocyanate without special changes in 20 formulation being necessary and without additional process steps having to be carried out after foam production.
We have found that this object is achieved by specific pressure conditions during foaming.
The present invention accordingly provides a process for producing fine-celled rigid foams based on isocyanate by reacting polyisocyanates with compounds containing at least two reactive hydrogen atoms in the presence of blowing agents, catalysts and, 30 if desired, further auxiliaries and/or additives in closed molds, wherein a) the reaction components are loaded with a gas before being introduced into the mold, b) the mold is pressurized with gas before or during introduction of the reaction components, 40 c) depressurization takes place in the mold after introduction of the reaction mixture into the mold and before the foam has set.
The reaction components are loaded with the gas at pressures of 45 from 0.1 to 26 bar.
- BASF Aktiengesellschaft 970100 O.Z. 0050/48367 The mold is pressurized to a pressure of from 0.1 bar to 25 bar, in particular from 0.5 bar to 15 bar. The mold is depressurized to from 0.1 bar to 10 bar, preferably from 0.9 bar to 2 bar, with the depressurization being carried out during the time from 5 0 seconds after introduction of the reaction mixture into the mold to the fiber time minus one second.
The pressure is generated by means of substances which are gaseous at room temperature and are inert toward the reaction 10 components, for example air, nigrogen, carbon dioxide, dinitrogen oxide, argon, helium or neon, in particular carbon dioxde.
To carry out the process of the present invention, it is 15 advantageous to likewise keep the reservoir for the polyurethane components as well as the product lines to the mixing head under pressure. The pressure here should be from 0 bar to 26 bar, in particular from 0.5 bar to 15 bar.
20 The pressure in the mold is here always less than the pressure at which the reaction components are loaded with the gas.
The process of the present invention can be employed for producing all rigid foams based on isocyanate which are produced 25 in molds, but particularly in the production of polyurethane (PUR) and polyurethane-polyisocyanurate (PIR) foam.
The following details may be provided in respect of the starting components used for such foams:
Suitable organic polyisocyanates are the aliphatic, cycloaliphatic, araliphatic and preferably aromatic polyfunctional isocyanates known per se, as are described, for 35 example, in EP-A-0 421 269 (column 4, line 49, to column 6, line 22) or in EP-A-0 719 807 (column 2, line 53, to column 4, line 21).
Polyisocyanates which have been found to be particularly useful 40 are diphenylmethane diisocyanate isomer mixtures (crude MDI) having a diphenylmethane diisocyanate isomer content of from 33 to 55 % by mass and polyisocyanate mixtures based on diphenylmethane diisocyanate which contain urethane groups and have an NCO content of from 15 to 33.6 % by mass.
- BASF Aktiengesellschaft 970100 O.Z. 0050/48367 AS compounds containing at least two hydrogen atoms which are reactive toward isocyanates, use is made according to the present invention of the above-described nitrogen-containing polyethers containing aromatic rings. In addition, further compounds 5 containing at least two hydrogen atoms which are reactive toward isocyanates can be employed. For this purpose, it is possible to use compounds which have two or more reactive groups selected from among OH groups, SH groups, NH groups, NH2 groups and CH acid groups, in particular OH groups, in the molecule.
Use is advantageously made of those having a functionality of from 2 to 8, preferably from 2 to 6, and a mean molecular weight of from 300 to 8000, preferably from 400 to 4000. Examples of compounds which have been found to be useful are 15 polyetherpolyamines and/or preferably polyols selected from the group consisting of polyether polyols, polyester polyols, polythioether polyols, polyesteramides, hydroxyl-containing polyacetals and hydroxyl-containing aliphatic polycarbonates or mixtures of at least two of the polyols mentioned. Preference is 20 given to using polyester polyols and/or polyether polyols. The hydroxyl number of these polyhydroxyl compounds is usually from 100 to 850 and preferably from 200 to 600. Further details regarding the compounds which can be used may be found, for example, in EP-A-0 421 269 (column 6, line 23 to column 10, line 25 5) or EP-A-0 719 807 (column 4, line 23 to column 7, line 55).
The rigid PUR foams can be produced with or without the concomitant use of chain extenders and/or crosslinkers. To modify 30 the mechanical properties, eg. the hardness, the addition of chain extenders, crosslinkers or, if desired, mixtures thereof can prove to be advantageous. Chain extenders and/or crosslinkers used are usually diols and/or triols having molecular weights of less than 400, preferably from 60 to 300. Preference is given to 35 using aliphatic, cycloaliphatic and/or araliphatic diols having from 2 to 14, preferably from 2 to 10, carbon atoms. Further details regarding these and further compounds which can be used may be found, for example, in EP-A-0 421 269 (column 10, lines 6 to 48).
If chain extenders, crosslinkers or mixtures thereof are employed for producing the rigid foams, they are advantageously used in an amount of from 0 to 20 % by weight, preferably from 2 to 8 % by weight, based on the weight of the compounds containing at least 45 two reactive hydrogen atoms.
CA 02246007 1998-09-2~
- BASF Aktiengesellschaft 970100 O.Z. 0050/48367 Catalysts used for producing the rigid PUR foams are, in particular, compounds which strongly accelerate the reaction of the compounds containing reactive hydrogen atoms, in particular hydroxyl groups, with the organic, modified or unmodified 5 polyisocyanates. However, the isocyanate groups can also be reacted with one another by means of suitable catalysts, preferably forming isocyanurate structures in addition to the adducts of isocyanates and the compounds containing hydrogen-active groups.
Catalysts used are thus, in particular, those substances which accelerate the reactions of the isocyanates, in particular urethane, urea and isocyanurate formation.
For this purpose, preference is given to tertiary amines, tin and bismuth compounds, alkali metal carboxylates and alkaline earth metal carboxylates, quaternary ammonium salts, s-hexahydrotriazines and tris(dialkylaminomethyl)phenols.
Further details regarding catalysts which can be used may be found, for example, in EP-A-0 719 807 (column 9, lines 5 to 56).
If desired, auxiliaries and/or additives can also be incorporated 25 into the reaction mixture for producing the rigid PUR foams.
Examples which may be mentioned are surface-active substances, foam stabilizers, cell regulators, flame retardants, fillers, dyes, pigments, hydrolysis inhibitors, fungistatic and bacteriostatic substances. Further details regarding the 30 compounds which can be used may be found, for example, in EP-A-0 421 269 (column 12, line 55 to column 14, line 25) or EP-A-0 719 807 (column 9, line 58 to column 13, line 17).
Blowing agents which can, if desired, be used for producing the 35 foams of the present invention include preferably water which reacts with isocyanate groups to form carbon dioxide. The amounts of water which are advantageously used are from 0.1 to 8 parts by weight, preferably from 1.5 to 5.0 parts by weight and in particular from 2.5 to 3.5 parts by weight, based on 100 parts by 40 weight of the compounds containing at least 2 active hydrogen atoms.
In admixture with water, it is also possible to use physically 45 acting blowing agents. Suitable physically acting blowing agents are liquids which are inert toward the organic, modified or unmodified polyisocyanates and have boiling points below 100~C, preferably below 50OC, in particular from -50~C to 30~C, at CA 02246007 1998-09-2~
BA~F Aktiengesellschaft 970100 O.Z. 0050/48367 atmospheric pressure so that they vaporize under the action of the exothermic polyaddition reaction. Examples of such preferred liquids are alkanes such as heptane, hexane, n- and iso-pentane, preferably industrial mixtures of n- and iso-pentanes, n- and 5 iso-butane and propane, cycloalkanes such as cyclopentane and/or cyclohexane, ethers such as furan, dimethyl ether and diethyl ether, ketones such as acetone and methyl ethyl ketone, alkyl carboxylates such as methyl formate, dimethyl oxalate and ethyl acetate and halogenated hydrocarbons such as methylene chloride, 10 dichloromonofluoromethane, difluoromethane, trifluoromethane, difluoroethane, tetrafluoroethane, chlorodifluoroethanes, 1,1-dichloro-2,2,2-trifluoroethane, 2,2-dichloro-2-fluoroethane and heptafluoropropane. Mixtures of these low-boiling liquids with one another and/or with other substituted or unsubstituted 15 hydrocarbons can also be used. Other suitable blowing agents are organic carboxylic acids such as formic acid, acetic acid, oxalic acid, ricinoleic acid and carboxyl-containing compounds.
Preference is given to using water, chlorodifluoromethane, 20 chlorodifluoroethanes, dichlorofluoroethanes, pentane mixtures, cyclohexane and mixtures of at least two of these, eg. mixtures of water and cyclohexane, mixtures of chlorodifluoromethane and l-chloro-2,2-difluoroethane and, if desired, water.
The amount of physically acting blowing agents required in addition to water can be readily determined as a function of the desired foam density and is from about 0 to 25 parts by weight, preferably from 0 to 15 parts by weight, per 100 parts by weight 30 of the compounds containing at least two active hydrogen atoms.
It may be advantageous to mix the modified or unmodified polyisocyanates with the inert physically acting blowing agents and thereby reduce the viscosity.
35 However, the starting materials except for the polyisocyanates are usually combined to form the polyol components.
To produce the foams of the present invention, the isocyanate components and the polyol components are combined and then 40 allowed to foam.
As mixing unit, preference is given to using the known high-pressure mixing heads by the high-pressure process which is described, for example, in Kunststoff-Handbuch, Volume VII, 45 Polyurethane, edited by G. Oertel im Carl-Hanser-Verlag, Munich, Vienna 1993, page 143 ff.
CA 02246007 1998-09-2~
BASF Aktiengesellschaft 970100 O.Z. 0050/48367 However, it is also possible to use the low-pressure mixing heads described in the same reference.
The process of the present invention enables the cell sizes of 5 all rigid foams based on isocyanate to be reduced, both the open-celled and the closed-celled types.
The process of the present invention is particularly advantageous 10 in the production of open-celled foams which can be used as core material for vacuum insulation units.
The invention is illustrated by the following examples.
15 Formulation A:
Polyetherol 1: 30 % of a tolylenediamine-initiated polyether polyol derived from ethylene oxide and propylene oxide and having a hydroxyl number of 400 mg KOH/g Polyetherol 2: 20 % of a polyetherol based on bisphenol A, diethanolamine, formaldehyde and propylene oxide and having a hydroxyl number of 530 mg KOH/g Polyetherol 3: 23 % of a polyetherol based on sucrose, glycerol and propylene oxide and having a hydroxyl number of 490 mg KOH/g Polyetherol 4: 5 % of a polyetherol based on propylene glycol and propylene oxide and having a hydroxyl number of 250 mg KOH/g 30 Polyetherol 5: 15 % of an amine-initiated polyetherol prepared using ethylene oxide and propylene oxide and having a hydroxyl number of 115 mg KOH/g Stabilizer: 3 % of silicone stabilizer Tegostab~ B8465 from Th. Goldschmidt Catalysts: 0.5 % of dimethylcyclohexylamine 0.7 % of pentamethyldiethylenetriamine 0.7 % of Dabco~ TMR3 from Air Products 40 Blowing agents:2 % of water 13 % of cyclopentane Polyisocyanate:Crude MDI Lupranat~M20A (NCO content 31.5 % by weight), BASF AG
Index: 135 CA 02246007 1998-09-2~
BASF Aktiengesellschaft 970100 O.Z. 0050/48367 Formulation B:
Polyetherol 1: 20 % of a polyetherol based on ethylenediamine and propylene oxide and having a hydroxyl number of 470 mg KOH/g Polyetherol 2: 40 % of a polyetherol based on sucrose, glycerol and propylene oxide and having a hydroxyl number of 490 mg KOH/g ~0 Polyetherol 3: 30 % of a polyetherol based on trimethylolpropane and propylene oxide and having a hydroxyl number of 555 mg KOH/g Polyesterol 4: 10 % of a polyesterol comprising castor oil and glycerol and having a hydroxyl number of 360 mg KOH/g Stabilizers and cell openers:
3 % of Tegostab~ B 8919 from Th. Goldschmidt 1 % of Tegostab~ B 8863Z from Th. Goldschmidt 1 % of Fluorad~ FC-430 from 3M
Catalyst: 5 % of Dabco~ AN20 from Air Products Blowing agents:0.5 % of water 7 % of cyclopentane 4 % of perfluorohexane Polyisocyanate:Crude MDI Lupranat~ M20A
(NCO content 31.5 % by weight); BAS~ AG
Index: 130 Formulation C:
Polyetherol 1: 78.5 % of a polyetherol based on sucrose, glycerol and propylene oxide and having a hydroxyl number of 490 mg KOH/g Polyetherol 2: 15 % of a polyetherol based on propylene glycol and propylene oxide and having a hydroxyl number of 105 mg KOH/g ~ Catalyst: 2 % of dimethylcyclohexylamine Stabilizer: 2.5 % of Polyurax~ SR321 from Deutsche BP Chemie GmbH
Blowing agent: 2 % of water ~5 Polyisocyanate:Crude MDI Lupranat~ M20W
(NCO content 31.5 % by weight), BASF AG
BASF Aktiengesellschaft 970100 O.Z. 0050/48367 Index: 110 The systems displayed the following laboratory values (free-foamed) A B C
Cream time [s] 10 11 15 Fiber time [s] 51 65 50 10 Foam density 31 58 52 [kg/m3]
Foaming was carried out by means of a Puromat~ high-pressure 15 foaming machine from Elastogran GmbH.
A cylindrical foam mold having a diameter of 20 cm and a height of 5 cm was used.
20 The open cell content was determined in accordance with ASTM D 2856-87, method B, the foam density was determined in accordance with DIN 53420, the cell diameter was determined in accordance with ASTM D 3576-77, the thermal conductivity was determined in accordance with DIN 52616 in a Hesto-Lambdakontrol Examples 1 to 6 30 Foaming of formulation A
Foaming was carried out as described above. The pressureconditions and the results obtained are shown in Table 1.
o ~
~ ul ~' Table 1: Comparison of the results for formulation A
Prepressure = pressure on the containers, counterpressure = pressure on the mold Gas used: nitrogen O
ExamplePlt;pressu~eCounter-- D~ u~ FoamCell diameter CTC CTC Open cell Remarks pressure tion time density content [mW/mK] [mW/mK]
[bar] [bar] [s] [kg/m3] [~Im] after 1 dayaner 1 week [%]
O O 0 27.6 300 19.8 19.8 2.3 C~ i 1 (C) 2 5 3 18 26.1 155 18.3 18.6 6.2 according to the present invention ~.
3 10 5 18 27.6 146 18.8 17.9 6.1 according to the ~
present invention ~, 4 10 4 18 26.7 140 n.d n.d. 6.3 according to the o present invention 24 27.4 145 n.d. n.d. 4.7 according to the present invention 6 10 5 10 26.3 199 n.d. n.d. 7.2 according to the ~
present invention ~
o o n.d.= not determined o CTC = coefficient of thermal conductivity ~
w o ~ Examples 7 to ll ~
c ~I
Foaming of formulation B
Foaming was carried out as described above. The pressures and the results obtained are shown in Table 2.
Table 2: Comparison of the results for formulation B
Prepressure = pressure on the containers, counterpressure = pressure on the mold n Gas used: nitrogen Example Pre- Counter- Depressuriza- FoamCell diameter Open cell Remarks pressure pressure tion time density content 1' ~J
[bar] [bar] [~] [kg/m3][~m] [~] o 7 0 0 0 37 136 96.9 comparison ~O
8 5 2 30 50.4 74 95.3 according to the present invention 9 10 5 30 50.1 61 96.6 according to the present invention ~
41.5 90 95.1 according to the present invention O
11 10 5 10 43.4 100 94 according to the ~
present invention w Examples 12 to 16 .
Formulation C was foamed as described. The pressure conditions are shown in Table 3.
~ ,.
O Table 3: Comparison of the results for formulaion C
Prepressure = pressure on the containers, counterpressure = pressure on the mold Gas used: carbon dioxide n Example Pre- Counter-Depressuriza- Foam Cell diameter Open cell Remarks pressure pressure tion time density content [bar] [bar] [s] [kg/m3] [~m] [%]
12 0 0 0 56 229 < 10 comparison ~ ~
13 5 0 15 73 197 < 10 according to the ~
present invention o 14 5 3 15 55 153 < 10 according to the 4 15 57 137 < 10 according to the present invention o 16 5 7 15 58 240 < 10 comparison ~
o BASF Aktiengesellschaft 970100 O.Z. 0050/48367 Examples 17 to 20 (comparison) 5 Formulation A was foamed at different pressures in the mixing head, but the polyurethane formative components were not loaded with gas and no pressure was built up in the mold.
The results are shown in Table 4.
Table 4 Example Output Pressure in the d-I- d II
[g/l] m; x; ng head [~m] [~m]
[bar]
d-I-: Cell size perpendicular to the foaming direction d II: Cell size in the foaming direction Examples 21 to 23 (comparison) The reaction components of formulation A were saturated with carbon dioxide at a pressure in the container of 8 bar and were 30 foamed in the mold without overpressure.
The results are shown in Table 5.
Loading [%] CTC [mW/mK3 d-I- d-II
after 1 day [~m] [~m]
none 0.0 % 19.6 201 240 CO2 0.4 % 19.9 220 226 CO2 0.8 % 20.1 282 298 CTC- coefficient of thermal conductivity d-I- cell size perpendicular to the foaming direction d II cell size in the foaming direction
present invention ~, 4 10 4 18 26.7 140 n.d n.d. 6.3 according to the o present invention 24 27.4 145 n.d. n.d. 4.7 according to the present invention 6 10 5 10 26.3 199 n.d. n.d. 7.2 according to the ~
present invention ~
o o n.d.= not determined o CTC = coefficient of thermal conductivity ~
w o ~ Examples 7 to ll ~
c ~I
Foaming of formulation B
Foaming was carried out as described above. The pressures and the results obtained are shown in Table 2.
Table 2: Comparison of the results for formulation B
Prepressure = pressure on the containers, counterpressure = pressure on the mold n Gas used: nitrogen Example Pre- Counter- Depressuriza- FoamCell diameter Open cell Remarks pressure pressure tion time density content 1' ~J
[bar] [bar] [~] [kg/m3][~m] [~] o 7 0 0 0 37 136 96.9 comparison ~O
8 5 2 30 50.4 74 95.3 according to the present invention 9 10 5 30 50.1 61 96.6 according to the present invention ~
41.5 90 95.1 according to the present invention O
11 10 5 10 43.4 100 94 according to the ~
present invention w Examples 12 to 16 .
Formulation C was foamed as described. The pressure conditions are shown in Table 3.
~ ,.
O Table 3: Comparison of the results for formulaion C
Prepressure = pressure on the containers, counterpressure = pressure on the mold Gas used: carbon dioxide n Example Pre- Counter-Depressuriza- Foam Cell diameter Open cell Remarks pressure pressure tion time density content [bar] [bar] [s] [kg/m3] [~m] [%]
12 0 0 0 56 229 < 10 comparison ~ ~
13 5 0 15 73 197 < 10 according to the ~
present invention o 14 5 3 15 55 153 < 10 according to the 4 15 57 137 < 10 according to the present invention o 16 5 7 15 58 240 < 10 comparison ~
o BASF Aktiengesellschaft 970100 O.Z. 0050/48367 Examples 17 to 20 (comparison) 5 Formulation A was foamed at different pressures in the mixing head, but the polyurethane formative components were not loaded with gas and no pressure was built up in the mold.
The results are shown in Table 4.
Table 4 Example Output Pressure in the d-I- d II
[g/l] m; x; ng head [~m] [~m]
[bar]
d-I-: Cell size perpendicular to the foaming direction d II: Cell size in the foaming direction Examples 21 to 23 (comparison) The reaction components of formulation A were saturated with carbon dioxide at a pressure in the container of 8 bar and were 30 foamed in the mold without overpressure.
The results are shown in Table 5.
Loading [%] CTC [mW/mK3 d-I- d-II
after 1 day [~m] [~m]
none 0.0 % 19.6 201 240 CO2 0.4 % 19.9 220 226 CO2 0.8 % 20.1 282 298 CTC- coefficient of thermal conductivity d-I- cell size perpendicular to the foaming direction d II cell size in the foaming direction
Claims (10)
1. A process for producing fine-celled rigid foam based on isocyanate by reacting polyisocyanates with compounds containing at least two reactive hydrogen atoms in closed molds, wherein a) the reaction components are loaded with gas under pressure before being introduced into the mold, b) the mold is pressurized before, during or after introduction of the reaction mixture, c) depressurization takes place in the mold after introduction of the reaction mixture into the mold and before the rigid foam has set.
2. A process as claimed in claim 1, wherein the polyurethane formative components are loaded with a gas at a pressure of from 1 bar to 26 bar.
3. A process as claimed in claim 1, wherein the pressure in the mold is from 0.1 bar to 25 bar.
4. A process as claimed in claim 1, wherein the pressure in the mold is from 0.5 bar to 15 bar.
5. A process as claimed in claim 1, wherein the pressure in the mold after depressurization is from 0.1 to 10 bar.
6. A process as claimed in claim 1, wherein the pressure in the mold is less than the pressure at which the polyurethane formative components are loaded with the gas.
7. A process as claimed in claim 1, wherein the depressurization in the mold is carried out during the time from 0 seconds after introduction of the reaction mixture to the fiber time minus 1 second.
8. A process as claimed in claim 1, wherein the gases with which the reaction components are loaded are substances which are gaseous at room temperature and are inert toward the reaction components.
9. A process as claimed in claim 1, wherein the gases with which the reaction components are loaded are selected from the group consisting of air, nitrogen, carbon dioxide, dinitrogen oxide, argon, helium, neon and mixtures thereof.
10. A process as claimed in claim 1, wherein the reaction components are, in particular, saturated with carbon dioxide and/or nitrogen.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DE19742568.2 | 1997-09-26 | ||
| DE19742568A DE19742568A1 (en) | 1997-09-26 | 1997-09-26 | Process for the production of fine-celled rigid foams based on isocyanate |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2246007A1 true CA2246007A1 (en) | 1999-03-26 |
Family
ID=7843744
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002246007A Abandoned CA2246007A1 (en) | 1997-09-26 | 1998-09-25 | Production of fine-celled rigid foams based on isocyanate |
Country Status (5)
| Country | Link |
|---|---|
| EP (1) | EP0904916B1 (en) |
| JP (1) | JPH11158308A (en) |
| AT (1) | ATE212280T1 (en) |
| CA (1) | CA2246007A1 (en) |
| DE (2) | DE19742568A1 (en) |
Families Citing this family (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2001012707A1 (en) * | 1999-08-17 | 2001-02-22 | Hunstman International Llc | Methods for improving the insulating properties of closed celled rigid polyurethane foams |
| DE10056251B4 (en) * | 2000-11-14 | 2006-06-08 | Basf Ag | Process for the production of polyurethane foams |
| DE10128458A1 (en) * | 2001-06-12 | 2003-02-13 | Battenfeld Gmbh | Foamed plastic component manufacture involves control of increased gas pressure in tool cavity to influence melt flow |
| DE10303882A1 (en) * | 2003-01-31 | 2004-08-12 | Hennecke Gmbh | Process for the production of molded polyurethane parts |
| EP3372625A1 (en) * | 2017-03-07 | 2018-09-12 | Covestro Deutschland AG | Polyurethane foam and method for its production |
Family Cites Families (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3088172A (en) * | 1956-05-12 | 1963-05-07 | Bayer Ag | Process for the production of molded cellular polyurethane plastics |
| BE719787A (en) * | 1968-08-22 | 1969-02-24 | ||
| US4133858A (en) * | 1977-12-14 | 1979-01-09 | Usm Corporation | Injection foam molding process |
| WO1982000297A1 (en) * | 1980-07-15 | 1982-02-04 | J Blackwell | Production of synthetic plastics foam material |
| DE4017517A1 (en) * | 1990-05-31 | 1991-12-05 | Braun Pebra Gmbh | METHOD AND DEVICE FOR PRODUCING PLASTIC FORM PARTS |
-
1997
- 1997-09-26 DE DE19742568A patent/DE19742568A1/en not_active Withdrawn
-
1998
- 1998-09-22 EP EP98117894A patent/EP0904916B1/en not_active Expired - Lifetime
- 1998-09-22 DE DE59802884T patent/DE59802884D1/en not_active Expired - Lifetime
- 1998-09-22 AT AT98117894T patent/ATE212280T1/en not_active IP Right Cessation
- 1998-09-25 CA CA002246007A patent/CA2246007A1/en not_active Abandoned
- 1998-09-28 JP JP10273493A patent/JPH11158308A/en not_active Withdrawn
Also Published As
| Publication number | Publication date |
|---|---|
| DE59802884D1 (en) | 2002-03-14 |
| EP0904916A3 (en) | 1999-07-14 |
| ATE212280T1 (en) | 2002-02-15 |
| DE19742568A1 (en) | 1999-04-01 |
| EP0904916A2 (en) | 1999-03-31 |
| JPH11158308A (en) | 1999-06-15 |
| EP0904916B1 (en) | 2002-01-23 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| EP0695322B1 (en) | Process for preparing rigid polyurethane foams | |
| RU2146267C1 (en) | Polyisocyanate-based polymers prepared from compositions including nonsilicone surfactants and method of preparation thereof | |
| EP0415599B1 (en) | Density reduction in flexible polyurethane foams | |
| US5886062A (en) | Process for the production of rigid polyurethane foams | |
| US4980388A (en) | Use of carbon dioxide adducts as blowing agents in cellular and microcellular polyureas | |
| US6001890A (en) | Open celled cellular polyurethane products | |
| AU722500B2 (en) | Process for the production of rigid polyurethane foams having low thermal conductivity | |
| CA2462387C (en) | Rigid, dimensionally stable polyurethane foams and a process for the production of such foams in which the foam pressure is reduced | |
| CA2060590A1 (en) | Manufacture of cellular elastomers and chemical compositions used therefor | |
| US6005016A (en) | Rigid polyurethane foam based on polyethers of TDA | |
| KR19990030103A (en) | Isocyanate Based Continuous Bubble Rigid Foam | |
| US5248703A (en) | Rigid polyurethane foams containing lithium salts for energy absorbing applications | |
| US5112879A (en) | Chemical blowing agent | |
| US5453455A (en) | Rigid polyurethane foams containing lithium salts for energy absorbing applications | |
| US5420169A (en) | Process for production of low density water-blown rigid foams with flow and dimensional stability | |
| CA1336118C (en) | Process for making low density flexible molded and slabstock polyurethane foams | |
| CA2246007A1 (en) | Production of fine-celled rigid foams based on isocyanate | |
| EP0605105A1 (en) | Process for rigid foams | |
| US5998494A (en) | Rigid polyurethane foams | |
| US5368769A (en) | Manufacture of cellular polymers and compositions therefor | |
| US5426124A (en) | Process for the production of moldings of polyurethane foams | |
| KR19990072113A (en) | Manufacturing method of hard foam material containing urethane group | |
| JPH0959409A (en) | Production of polyurethane foam | |
| MXPA98007788A (en) | Production of rigid foams of fine cells based on isocian | |
| CA2063688A1 (en) | Manufacture of cellular polymers and compositions therefor |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| FZDE | Discontinued |