EVACUATED INSULATION PANELS

Abstract: Process for making evacuated insulation panels comprising the steps of a) making a block of (semi-)rigid open celled polyurethane or urethane-modified polyisocyanurate foam via a slabstock process, b) cutting said foam block into foam panels, c) enveloping at least one of said panels in a gastight vessel, d) evacuating the whole to an internal pressure of about 5 mbar or less, and e) hermetically sealing the whole, wherein the cutting of the foam block into foam panels is done parallel to the rise direction of the foam.

Description: DESCRIPTION EVACUATED INSULATION PANELS This invention relates to evacuated insulation panels filled with open celled (semi-) rigid polyurethane or urethane-modified polyisocyanurate foam, a method for the production thereof and their use for thermal insulation purposes. Evacuated insulation panels and methods for their production are known Evacuated insulation panels having a reduced internal pressure are known for various uses including use in refrigeration appliances where they greatly enhance the degree of thermal insulation within the caomet of the appliance Such evacuated insulation panels generally comprise a low thermal conductivity filler material and a vessel formed of a gastight film enveloping said filler, the whole being evacuated to an internal pressure of about 5 mbar or less and then hermetically sealed. Besides insulation the filler has also the function of supporting the skin of the vessel so that it does not collapse when it is evacuated. The pressure level to which the vessel must be evacuated in order to obtain a satisfactory insulating property depends on the specific filler material. Also the extent of increase in thermal conductivity with internal pressure increase with lapse of time (owing l.a to gases such as air and water vapor diftusmg gradually) depends on the type of filler material Known filler materials for use in such evacuated insulation panels include finely divided inorganic powders such as fumed silica, silica dust, precipitated silica, precipitated silica/fly ash mixtures, alumina, fine perlite and fiberglass. It has also been proposed, in Japanese Patent Application Kokai No. 133870/82, to use organic foamed materials having open cells as the core material in evacuated insulation panels, for example, open celled rigid polyurethane foam (see European Patent Publications Nos 0498628 and 0188806) . The rigid open celled polyurethane foams for use as filler in evacuated insulation panels are usually made either via a lamination process or via a slabstock process. In a lamination process the reaction mixture is poured onto a moving lower substrate material. The foam rises to the surface of the upoer substrate inside the laminator. An exact panel thickness (usually 20 cm or less) is obtained by setting the desired distance between the upper and lower conveyor. After curing in the conveyor and going through a cooling off stretch, the foam panel can be trimmed (to remove any foam skin having high closed cell contents) and cut to length. The amount of scrap foam removed m the initial trimming can be quite substantial; therefore the slabstock process is the preferred route to make open celled rigid polyurethane foam for use as filler in evacuated insulation panels. In a slabstock process the reaction mixture is usually poured into a mould of the required dimensions. Often the top of the rising foam is flatten by using a floating lid. Blocks of foam are obtained which, after cooling and curing, are cut into panels of the required size. This cutting is normally done perpendicular to the rise direction of the foam. Blocks can be made continuously, semi-cont nuously or discontinuously. It is important to use as filler a rigid open celled polyurethane foam having a thermal conductivity as low as possible in order to obtain evacuated insulation panels having good thermal insulation properties also after a prolonged period of time. It is an object of the present invention to provide an evacuated insulation panel filled with rigid open celled polyurethane foam of lower thermal conductivity than the panels of the prior art. Accordingly the present invention provides a process for making evacuated insulation panels comprising the steps of a) making a block of (semi-) rigid open celled polyurethane or urethane-modified polyisocyanurate foam via a slabstock process, b) cutting said foam block into foam panels, c) enveloping at least one of said panels in a gastight vessel, d) evacuating the whole to an internal pressure of about 5 mbar or less, and e) hermetically sealing the whole, characterised in that the cutting of the foam block into foam panels in step b) is done parallel to the rise direction of the foam. Foam panels cut parallel to rise (vertically) show a much lower thermal conductivity than foam panels cut perpendicular to rise (horizontally) and consequently evacuated insulation panels made thereof have better thermal insulation properties. The rigid open celled polyurethane or urethane-modified polyisocyanurate foam for use m the evacuated insulation panels of the present invention are made by reacting an organic polyisocyanate composition with a polyfunctional isocyanate-reactive composition in the presence of a blowing agent. Suitable organic polyisocyanates for use in the preparation of open celled rigid polyurethane or urethane-modified polyisocyanurate foams include any of those known in the art for the preparation of rigid polyurethane or urethane-modified polyisocyanurate foams, and in particular the aromatic polyisocyanates such as diphenylmethane dnsocyanate in the form of its 2,4'-, 2,2'- and 4,4'-ιsomers and mixtures thereof, the mixtures of diphenylmethane dnsocyanates (MDI) and oligomers thereof known m the art as "crude" or polymeric MDI (polymethylene polyphenylene polyisocyanates) having an isocyanate functionality of greater than 2, toluene dnsocyanate in the form of its 2,4- and 2,6-ιsomers and mixtures thereof, 1, 5-naphthalene dnsocyanate and 1, 4-dιιsocyanatobenzene. Special mention may be made of the so-called MDI variants (diphenylmethane dnsocyanate modified by the introduction of urethane, allophanate, urea, biuret, carbodnmide, uretonimme or isocyanurate residues) . Other organic polyisocyanates which may be mentioned include the aliphatic dnsocyanates such as isophorone dnsocyanate, 1, 6-dιιsocyanatohexane and 4,4' -diisocyanatodicyclohexylmethane . Polyfunctional isocyanate-reactive compositions for use in the preparation of open celled rigid polyurethane or urethane-modified polyisocyanurate foams include any of those known in the art for the preparation of rigid polyurethane or urethane-modified polyisocyanurate foams. Of particular importance for the preparation of rigid foams are polyols and polyol mixtures having average hydroxyl numbers of from 300 to 1000, especially from 300 to 700 mg KOH/g, and hydroxyl functionalities of from 2 to 8, especially from 3 to 8. Suitable polyols have been fully described in the prior art and include reaction products of alkylene oxides, for example ethylene oxide and/or propylene oxide, with initiators containing from 2 to 8 active hydrogen atoms per molecule. Suitable initiators include: polyols, for example glycerol, trimethylolpropane, triethanolamme, pentaerythπtol, sorbitol and sucrose; polyammes, for example ethylene diamine, tolylene diamme, diaminodiphenylmethane and polymethylene polyphenylene polyammes; and ammoalcohols, for example ethanolamme and diethanolamine; and mixtures of such initiators. Other suitable polymeric polyols include polyesters obtained by the condensation of appropriate proportions of glycols and higher functionality polyols with dicarboxylic or polycarboxylic acids. Still further suitable polymeric polyols include hydroxyl terminated polythioethers, polyamides, polyesteram des, polycarbonates, polyacetals, polyolefins and polys loxanes . The quantities of the polyisocyanate compositions and the polyfunctional isocyanate-reactive compositions to be reacted will depend upon the nature of the rigid polyurethane or urethane-modified polyisocyanurate foam to be produced and will be readily determined by those skilled in the art. The preparation of open celled rigid polyurethane or urethane-modified polyisocyanurate foam may be carried out in the presence of any of the blowing agents known in the art for the preparation of rigid polyurethane or urethane-modified polyisocyanurate foams. Such blowing agents include water or other carbon dioxide-evolving compounds, such as isocyanate- reactive cyclic compounds, or inert low boiling compounds having a boiling point of above -70°C at atmospheric pressure. Suitable inert blowing agents include, for example, hydrocarbons, dialkyl ethers, alkyl alkanoates, aliphatic and cycloaliphatic hydrofluoroalkanes, hydrochlorofluoroalkanes, chlorofluoroalkanes, and fluorine-containing ethers. Suitable hydrocarbon blowing agents include lower aliphatic or cyclic hydrocarbons such as n-pentane, isopentane, cyclopentane, neopentane, hexane and cyclohexane. Where water is used as blowing agent, the amount may be selected in known manner to provide foams of the desired density, typical amounts being in the range from 0.05 to 5 % by weight based on the total reaction ingredients, although it may be a particular embodiment of the present invention to incorporate up to 10 % by weight or even up to 20 % by weight of water. The total quantity of blowing agent to be used in a reaction system for producing cellular polymeric materials will be readily determined by those skilled in the art, but will typically be from 2 to 25 % by weight based on the total reaction system. The open celled rigid polyurethane or urethane-modified polyisocyanurate foams to be used in the present invention may be of normal cell size, i.e. having cell sizes in the range 5 mm to 0.1 mm. In order to further lower the thermal conductivity open celled rigid polyurethane or urethane-modified polyisocyanurate foams having decreased cell sizes (in the range 50 to 150 micron) are preferably used. These fine celled open celled rigid polyurethane or urethane-modified polyisocyanurate foams can be obtained by incorporating an insoluble fluorinated compound into the foam-forming mixture or by air-nucleation. The term insoluble as used herein with reference to the insoluble fluorinated compound to be used in the preparation of fine celled open celled rigid polyurethane or urethane-modified polyisocyanurate foam is defined as showing a solubility in either the isocyanate-reactive composition or the polyisocyanate composition with which it is to be blended of less than 500 ppm by weight at 25°C and atmospheric pressure. Insoluble fluorinated compounds for use in the preparation of fine celled open celled rigid polyurethane or urethane-modified polyisocyanurate foam include any of those disclosed in US-P-4, 981, 879, US-P-5, 034, 424, US-P- 4,972,002, EP-A-0508649, EP-A-0498628 and WO 95/18176, incorporated herein by reference. The term substantially fluorinated as used herein with reference to the insoluble, substantially fluorinated compound to be used in the preparation of fine celled open celled rigid polyurethane 'or urethane-modified polyisocyanurate foam is to be understood to embrace compounds in which at least 50 % of the hydrogen atoms of the unfluonnated compounds are replaced by fluorine. Suitable compounds include substantially fluorinated or perfluoπnated hydrocarbons, substantially fluorinated or perfluonnated ethers, substantially fluorinated or perfluonnated tertiary amines, substantially fluorinated or perfluonnated amino-ethers and substantially fluorinated or perfluonnated sulphones. Preferred insoluble perfluonnated compounds include perfluoro-n-pentane, perfluoro-n-hexane, perfluoro N-methylmorpholme and perfluoro (4-methylpent- 2-ene) . Certain insoluble fluorinated compounds suitable for use in the preparation of fine celled open celled rigid polyurethane or urethane-modified polyisocyanurate foam may themselves act as blowing agents under the conditions pertaining to the foam-forming reaction, particularly where their boiling point is lower than the exotherm temperature achieved by the reaction mixture. For the avoidance of doubt, such materials may, partly or completely, fulfil the function of blowing agent in addition to that of insoluble fluorinated compound. The amount of the insoluble fluorinated compound to be used in the preparation of fine celled open celled rigid polyurethane or urethane- modified polyisocyanurate foam ranges from 0.05 to 10 %, preferably from 0.1 to 5 %, most preferably from 0.6 to 2.3 % by weight based on the total foam- for mg composition. The insoluble fluorinated compound will usually be incorporated in the foam- formmg reaction mixture in the form of an emulsion or preferably a microemulsion in one of the manor components, that is to say in the isocyanate-reactive component and/or the polyisocyanate component. Such emulsions or microemulsions may be prepared using conventional techniques and suitable emulsifying agents. Emulsifying agents suitable for preparing stable emulsions or microemulsions of fluorinated liquid compounds in organic polyisocyanates and/or isocyanate-reactive compounds include surfactants chosen from the group of nonionic, ionic (anionic or cationic) and amphotenc surfactants . Preferred surfactants are fluoro surfactants, silicone surfactants and/or alkoxylated alkanes . The amount of emulsifying agent used is between 0.02 and 5 pbw per 100 pbw of foam-forming reaction system and between 0.05 and 10 pbw per 100 pbw of polyisocyanate or polyol composition. In addition to the polyisocyanate and polyfunctional isocyanate-reactive compositions and the blowing agent, the foam-forming reaction mixture will commonly contain one or more other auxiliaries or additives conventional to formulations for the production of open celled rigid polyurethane and urethane-modified polyisocyanurate foams. Such optional additives include crossl kmg agents, for examples low molecular weight polyols such as triethanolam e, foam-stabilising agents or surfactants, for example siloxane-oxyalkylene copolymers, urethane catalysts, for example tin compounds such as stannous octoate or dibutyltin dilaurate or tertiary amines such as dimethylcyclohexylamine or tπethylene diamine, fire retardants, for example halogenated alkyl phosphates such as tris chloropropyl phosphate or alkyl phosphonates, smoke suppressants, organic or inorganic fillers, thixotropic agents, dyes, pigments, mould release agents, and cell-opening agents such as inert particles, polymer particles (such as polymer polyols) , specific surfactants, incompatible liquids such as solvents or polyols, inorganic fillers such as bentomte clays, silica particles (particularly fumed silica), metal flakes and stearates. A particularly preferred process to make open celled rigid polyurethane or urethane-modified polyisocyanurate foam for use according to the present invention comprises the step of reacting an organic polyisocyanate composition with an isocyanate-reactive material in the presence of an isocyanate-reactive cyclic compound of formula: 0 ti (I) (CR 2 ) n CR 2 wherein Y is 0 or NR 1 wherein each R 1 independently is a lower alkyl radical of C j -C 6 or a lower alkyl radical substituted with an isocyanate-reactive group; each R independently is hydrogen, a lower alkyl radical of C J -C J or (CH 2 ) m -X wherein X is an isocyanate-reactive group which is OH or NH 2 and m is 0, 1 or 2; and n is 1 or 2; with the proviso that at least one of R 1 or R is or comprises an isocyanate- reactive group. A preferred compound of formula (I) wherein Y is 0 is an isocyanate-reactive cyclic carbonate which is glycerol carbonate. Preferred compounds of formula (I) wherein Y is NR 1 are isocyanate-reactive cyclic ureas of formula: 0 H0-CH,-N N-CH 2 -0H (ID H-C - ■ C-H i I OH OH and 0 li C. CH 3 - N-CH 3 (III) H-C C-H I I OH OH The isocyanate-reactive cyclic blowing promotor is used in amounts ranging from 0.1 to 99 %, preferably from 1 to 60 %, more preferably from 1 to 10 % by weight based on the total isocyanate-reactive material. The process is preferably carried out in the presence of a metal salt catalyst. Preferred metal salt catalysts are those selected among group la and group Ila metal salts, more preferably among group la and group Ila metal carboxylates . Particularly suitable metal salt catalysts are potassium acetate and potassium ethylhexoate (for example, Catalyst LB available from Imperial Chemical Industries) . The metal salt catalyst is used in amounts ranging from 0.01 to 3 % by weight based on the total reaction system. Alternatively aminoalcohol catalysts can be used in the above process as described in WO 98/54239, incorporated herein by reference. A preferred aminoalcohol catalyst is 2- (2-dimethylaminoethoxy) ethanol. The aminoalcohol catalyst is generally used in amounts varying between 0.1 and 3 % by weight based on total reaction system. Amme catalysts can be used together with the metal salt catalyst or the aminoalcohol catalyst described above. Examples of suitable tertiary amine catalysts include dimethylcyclohexylam e, bis (dimethylaminoethyl) ether, tetramethylhexane diamine, triethylenediamine, N-methylmorpholine, pentamethyldiethylenetriamine, tetramethylethylenediam e, 1-methyl-4- dimethylammoethylpiperazine, 3-methoxy-N-dιmethylpropylamιne, N- ethylmorpholme, diethylethanolamine, N-cocomorpholme, N,N-dιmethylyl- N ', N ' -dimethyl isopropylpropylenediamine , N , N-diethyl- 3- diethylammopropylamine, dimethylbenzylam e . The amme catalyst is used in amounts ranging from 0.01 to 1.5 % by weight based on the total foam. In order to decrease the closed cell content particularly in conditions of overpack a supplemental cell opening agent selected from the group consisting of fatty acids, fatty acid amines, fatty acid amides and fatty acid esters can be used as described in GB 2324798, incorporated herein by reference. Examples of suitable fatty acid derivative cell opening agents include tallow diamines (which are complex mixtures of C 16 -C 30 dia mes), mixtures of tallow diammes with fatty acid esters such as the commercially available products INT 494/792/0, 494/792/1, 494/792/2 and 494/792/4 available from Munch Chemie-Labor and the following fatty acid diammes C 19 H 3β (NH 2 ) 2 , C 23 H 46 (NH 2 ) 2 and C 25 H 50 (NH 2 ) 2 . These fatty acid based additional cell opening agents are used in amounts of between 0.1 and 20 % by weight, preferably between 0.5 and 5 % by weight and most preferably between 0.5 and 2 % by weight based on the foam. Further useful additives for use in the above described process include polyethylene glycols containing from 1 to 10 ethyleneoxy units, antioxidants such as Irganox 1135, Irganox 1010 and Irgafos TNPP, additional silicone- based cell opening agents such as Ortagol 501 and Tegostab B8919 (both available from Goldschmidt) , Additive 6164 (available from OSi) and silicones of the DC-200 series (available from Dow Corning) . Isocyanate indices of from 70 to 140 will typically be used in operating the above described method but lower indices may be used if desired. Higher indices, for example 150 to 500 or even up to 3000, may be used in conjunction with trimensation catalysts to make foams containing isocyanurate linkages. Preferred indices lie m the range 90 to 250, more preferably 100 to 120. The rigid open celled polyurethane or urethane-modified polyisocyanurate foam for use according to the present invention is made via a slabstock process . Slabstock foam is usually made continuously by metering the foam reactants in the required proportions to a mixing head. The metered materials are mechanically mixed and nucleated and, in the widely-used traditional process, are immediately distributed on the bottom lmmg of a continuously moving trough formed by a horizontal bottom paper or foil and two vertical s de papers or foils, carried on a long conveyor at a controlled and adjustable speed. The process can also be carried out discont uously by moulding individual blocks of foam; this involves mixing a batch of foam reaction mixture and transferring it rapidly into a mould. The rising foam is formed into a flat-topped block by the use of a floating lid. The process requires that the measured components be thoroughly mixed and poured into the mould within a few seconds before the polymerisation reaction has caused significant increase in the viscosity of the mix. An essential requirement in slabstock manufacture is the provision of a separate, vented storage area where freshly made blocks of hot foam must be stored until cool. This area should be monitored and equipped with fire detection and/or sprinkler systems. The foam emerging from continuous foaming machines is usually cut into predetermined lengths, weighed, marked to indicate the grade of foam, the size and weight of the block, and the date of manufacture, and transferred to the hot foam store by automatic machinery. Some 12 to 14 hours after manufacture, when the blocks of foam have cooled and cured, they may be cut into the sizes required for the final product. Where necessary, the first stage is usually to trim the sides and top of each block, using vertical and horizontal band-knives, to produce a completely usable rectangular block having flat, uniform faces. The amount of scrap foam removed in this initial trimming varies with the size of the block and the type of production machine used to make the foam. The trimming loss varies inversely with the block size. The trimmed block of foam is cut into pieces by band-knives or high speed cutting wires. Wastage at this stage depends only on the geometry of the parts required. Blocks of rigid open celled polyurethane or urethane-modified polyisocyanurate foams are made with dimensions usually varying between 30 cm x 50 cm x 50 cm and 50 cm x 1.5 m x 5 . The height of the foam blocks is usually limited to 40-50 cm due to the scorching risk. Typical continuous blocks are 50 cm high, 1.2 m wide and 2 to 3 m in length. The obtained foam blocks are cut into foam panels of the desired size. This cutting is done according to the present invention in a direction parallel to the rise direction of the foam (vertical slicing) . Foam skin is removed to ensure a very low content of closed cells. Panel sizes vary between 1 cm x 20 cm x 40 cm and 10 cm x 45 cm x 2 m. Due to the limitation in height of the foam blocks the panels cut therefrom may not be wide enough (maximum 45 cm) ; two or more of these panels may then be stuck together and enveloped in the gastight vessel to make the evacuated insulation panel. General descriptions of the construction of evacuated insulation panels and their use m thermal devices can be found in US Patents Nos 5,066,437, 5,032,439 and 5,076,984 and European Patent Publications Nos 434266, 434225 and 181778, all incorporated herein by reference as well as the references mentioned therein. Suitable enveloping vessels need to be highly impermeable for gases as the gas permeation rate of the vessel directly affects both the occurence of heat leakage and thus the thermal insulation efficiency of the resulting evacuated insulation panel as well as the operating lifetime of the panel. Also, they should prevent transmission of heat by conduction or radiation, be easily sealable by heat sealing and, preferably, flexible. Materials suitable for the vessel include plastics such as polyester, polyv ylidene chloride, polypropylene and polyvinyl alcohol. Preferably the plastics film is vapor deposited with a metallic film or laminated with a metallic foil providing for higher protection against vacuum leak. The plastic bag may also include a thermoplastic heat sealing layer consisting of a thermoplastic resin having a relatively low melting point (lower than 200°C) . Examples of suitable thermoplastics include polyolefins, such as low density polyethylene, high density polyethylene and polypropylene, polyacrylonitrile, polyvinylidenechlonde and copolymers thereof, and polyamine, such as nylon 11 and nylon 12, or a similar synthetic resin. For the film deposited on or foil laminated with the plastics film metals can be used such as aluminum, titanium, lead, iron and alloys thereof or tin and its alloys, such as tin alloys with antimony, bismuth and copper or mixtures thereof. Preference is given to a laminate of a thin Al foil. It is preferred to precondition the insulating filler material prior to placement in the gastight envelope. This preconditioning involves heating and, optionally, agitating the filler material preferably under reduced pressure in order to remove contaminants from the surface of the filler. The removal of filler contaminants improves inter alia the expected panel life. Further the removal of contaminants reduces the time required to evacuate the vessel thereby reducing the time and cost associated with the manufacture of an evacuated insulation panel. To improve the performance of the evacuated insulation panel, materials are provided within the sealed panels to absorb or otherwise interact with gases and vapors that remain due to imperfect evacuation, that permeate the enclosure from the outside atmosphere or evolve from the polyurethane foam filler itself. Such materials are known as getters and may include, for example, granulated calcium sulfate or microporous banumoxide which is excellent in removing water vapor, activated carbon to remove organic gases, metals to absorb oxygen and nitrogen and zeolites to adsorb carbon dioxide and nitrogen. Other suitable getter materials are described US Patents Nos 4,000,246, 4,444,821, 4,663,551, 4,702,986, 5,191,980, 5,312,606, 5,312,607 and 4,726,974, WO 93/25843 and in European Patent Publications Nos 434266 and 181778. Refrigeration appliance is only a single example of a product that can utilise evacuated insulation panels. They can also form part of an insulated building panel. Other environments having a hot side and a cold side could also benefit from the use of the present invention, for example water heaters. The evacuated insulation panels can be easily arranged in the door and walls of a refrigerator. They are generally attached by adhesive to the walls of the thermal device to be insulated and then foamed-m-place with a liquid organic material such as polyurethane. The polyurethane foam then assists in holding the panels between the walls and also provides additional insulation. The invention is illustrated but not limited by the following examples. EXAMPLE 1 Blocks (40 cm in height, 1.2 m wide, 3 m long) of open celled rigid polyurethane foam were made using the ingredients listed below in Table 1. The blocks were made via a continuous process using a low pressure dispensing machine at 23°C. The polyol blend was pre-nucleated with air (10 %) to assist nucleation. The blocks were left to post cure for 3 days prior to cutting and testing. One block of foam was cut perpendicular to rise into panels of dimensions 30 cm x 30 cm x 3 cm so that the thickness of the foam panel is parallel to the rise direction (schematically presented as panel 2 in figure 1) . The density of the foam panel was 51.9 kg/m 3 and the closed cell content 0.2 %. The other block of foam was cut parallel to rise into panels of dimensions 3 cm x 30 cm x 30 cm so that the thickness of the foam panel is perpendicular to the rise direction (schematically presented as panel 1 in figure 1) . The density of the foam panel was 56.5 kg/m 3 and the closed cell content 0.5 %. Two evacuated insulation panels were made in a identical manner, one containing the horizontally sliced foam panel (panel 2) and the other one containing the vertically sliced foam panel (panel 1) . The foam panels were first preconditioned at 150°C for 10 minutes and then enveloped in a film (commercially available from Toyo) , evacuated to a pressure of 0.02 mbar and hermetically sealed. The initial lambda value of both panels was measured: 8.6 mW/mK for panel 2 and 5.4 mW/mK for panel 1. The thermal conductivity of both foam panels was also measured as a function of pressure. The results are shown in Figure 2. These results show that evacuated insulation panels comprising vertically sliced foam panels yield substantially improved insulation properties than evacuated insulation panels comprising horizontally sliced foam panels. Table 1 Polyol 1 is a polyether polyol of OH value 495 g KOH/g. Polyol 2 is a polyether polyol of OH value 420 mg KOH/g. PEG 200 is a polyethylene glycol of molecular weight 200. Fixapret is an isocyanate-reactive cyclic urea available from BASF. Surfactant is a silicone surfactant. Texacat ZR70 is a tertiary-dimethylamino ether monol catalyst available from Huntsman. Co-Catalyst is a tertiary amine catalyst. Cell Opener is a cell opening agent. Isocyanate is a polymeric MDI.

Claims: CLAIMS 1. Process for making evacuated insulation panels comprising the steps of a) making a block of (semi-) rigid open celled polyurethane or urethane-modified polyisocyanurate foam via a slabstock process, b) cutting said foam block into foam panels, c) enveloping at least one of said panels in a gastight vessel, d) evacuating the whole to an internal pressure of about 5 mbar or less, and e) hermetically sealing the whole, characterised in that the cutting of the foam block into foam panels is done parallel to the rise direction of the foam. 2. Process according to claim 1 wherein the (semi-) rigid open celled polyurethane or urethane-modified polyisocyanurate foam is made by reacting an organic polyisocyanate composition with a polyfunctional isocyanate-reactive composition in the presence of an isocyanate- reactive cyclic compound of formula: wherein Y is 0 or NR 1 wherein each R 1 independently is a lower alkyl radical of C j -Cg or a lower alkyl radical substituted with an isocyanate- reactive group; each R independently is hydrogen, a lower alkyl radical of Ci-C 6 or (CH 2 ) ra -X wherein X is an isocyanate-reactive group which is OH or NH 2 and m is 0, 1 or 2; and ii is 1 or 2; with the proviso that at least one of R 1 or R is or comprises an isocyanate-reactive group. 3. Process according to claim 2 wherein the isocyanate-reactive cyclic blowing promotor is a cyclic urea of formula or CH,-N N-CH, ( III ) H-C C-H I I OH OH 4. Process according to claim 2 or 3 wherein the process is carried out in the presence of a metal salt catalyst and/or an aminoalcohol catalyst . 5. Process according to any one of claims 2 to 4 wherein the process is carried out in the presence of a cell opening agent selected from the group consisting of fatty acids, fatty acid amines, fatty acid amides and fatty acid esters. 6. Evacuated insulation panel obtainable by the process as defined in any one of the preceding claims. 7. Evacuated insulation panel according to claim 6 also comprising a getter. 8. Process for making a (semi-) rigid open celled polyurethane or urethane-modified polyisocyanurate foam panel comprising the steps of making a block of (semi-) rigid open celled polyurethane foam via a slabstock process and cutting the foam block into foam panels parallel to the direction of rise of the foam.

Inventors: BAGUE LUC RENE GABRIEL, HAMILTON ALAN JONES, BAGUE, LUC, RENE, GABRIEL, HAMILTON, ALAN, JONES
Applicants: HUNTSMAN ICI CHEM LLC, HUNTSMAN ICI CHEMICALS LLC
Application year: 1999
Main classification: C08G18
IPC codes: C08G18, F16L59