WO1996021564A1

WO1996021564A1 - Insulation panel comprising a co2 barrier film

Info

Publication number: WO1996021564A1
Application number: PCT/US1996/000429
Authority: WO
Inventors: Henri J. M. Gruenbauer; Kees-Jeen Van Duin; Laura J. Cikut; Pete J. Masloski
Original assignee: The Dow Chemical Company
Priority date: 1995-01-10
Filing date: 1996-01-11
Publication date: 1996-07-18
Also published as: AU4754796A

Abstract

This invention relates to an insulation panel which comprises a first wall, a second wall being a synthetic resin, and positioned between the first and second wall a foamed-in-situ polyurethane foam obtained in the presence of an expanding agent consisting substantially of carbon dioxide. The thermal insulation retention properties of the panel are significantly improved by the presence of a carbon dioxide diffusion barrier film interposed between the second wall and the polyurethane foam. The barrier film is a thermoplastic polyester resin which is a homo- or co-polymer adduct of an aromatic dicarboxylic acid and an active hydrogen-containing material.

Description

INSULATION PANEL COMPRISING A C02 BARRIER FILM

This invention pertains to an insulation panel comprising a carbon dioxide barrier film and a rigid polyurethane polymer wherein the gas content of the cell consists substantially of carbon dioxide. More specifically this invention relates to the use of a barrier film consisting

5 of a polyester polymer to minimize the loss of carbon dioxide from the cellular polyurethane. Polyurethane foam is prepared by reacting a polyisocyanate with a polyester or polyether polyol in the presence of a physical blowing agent Traditionally, the physical blowing agent of choice has been trichiorof luoromethane due to its convenient boiling point and due to its ability to confer attractive thermal insulation properties to the resulting foam. In

10 recent times the continued use of certain perchlorof luorocarbons, including trichiorof luoromethane, as physical blowing agent has been brought into question due to the association of such substances with the loss of ozone from the earths' atmosphere. An interim solution has been to use alternative physical blowing agents exhibiting a significantly reduced ozone depletion potential such astrichlorodifluoroethane (R-123), dichlorofluoroethane (R-

15 141b) or tetrafluoroethane (R-134a). However, such alternative physical blowing agents are significantly more expensive and do not accord to the foam the same attractive thermal insulation properties as the perchlorof luorocarbon blowing agents.

The use of such expensive alternative physical blowing agents to prepare the polyurethane foam can be avoided by selection of, or example, carbon dioxide as the

20 expanding agent. Foam prepared in such a manner has initially acceptable thermal insulation properties but which, due to the ability of carbon dioxide to readily diffuse out of the polyurethane cell cavities, quickly declines to a commercially unacceptable level. Accordingly, it would be desirable to provide a means of minimizing or preventing the loss of carbon dioxide from the foam.

25 It is therefore desirable to consider the possibility of modifying or using an alternative barrier film. Desirably such an alternative barrier film should allow for efficient preparation of the shaped liner employed in the appliance unit and more importantly be able to minimize or prevent loss of carbon dioxide from the polyurethane foam, as evidenced by a better long-term retention of thermal insulation performance.

30 It has now been discovered that thermoplastic polyester material can adequately function as a carbon dioxide diffusion barrier in insulation panels containing polyurethane foam prepared in the presence of an expanding agent consisting substantially of carbon dioxide. in one aspect, this invention is an insulation panel which comprises,

35 a) a first wall element; b) a second wall element being a synthetic resin; c) a foamed-in-situ polyurethane foam, obtained by reacting a polyisocyanate with a polyahl in the presence of an expanding agent, contiguous to said first wall element and positioned between said first wall element and said second wall element; and d) a barrier film being a thermoplastic polyester resin interposed between said foamed-in-situ polyurethane foam and said second wall element, characterized in that: i) the expanding agent consists substantially of carbon dioxide; and ii) the thermoplastic polyester resin is a homo- or co-polymer adduct of an aromatic dicarboxylic acid and an active hydrogen-containing material.

In a second aspect, this invention is an insulation panel which comprises, a) a first wall element; b) a second wall element being a synthetic resin; c) a foamed-in-situ polyurethane oam, obtained by reacting a polyisocyanate with a polyahl in the presence of an expanding agent, contiguous to said first wall element and positioned between said first wall element and said second wall element; and d) a barrier film being a thermoplastic polyester resin, interposed between said foamed-in-situ polyurethane foam and said second wall element, characterized in that: i) the expanding agent consists of carbon dioxide; ") the barrier film has a thickness of less than 50, but at least 5 microns; and iii) the thermoplastic polyester resin, used as barrier film, is a polyethyleneterephthalate resin or a glycol-modified polyethylene terephthalate resin.

Our investigations have surprisingly shown that the use of such polyester resin as a diffusion barrier film adequately minimizes loss of carbon dioxide from the polyurethane foam thereby permitting better retention of the panels' thermal insulation properties and reducing susceptibility to dimensional instability. The ability of such a polyester resin film to function in this manner is unexpected in that the resin itself is not especially noted for its ability to limit carbon dioxide diffusion. In contrast, general carbon dioxide diffusion data for such a polyester resin suggests it would be unsuitable for the purpose in which it is put to in this invention. While it is not fully understood how this invention operates, it is presently believed that the retention of carbon dioxide within the foam is, in part, a consequence of the good surface adhesion of the polyester resin to the polyurethane foam. Such adhesion minimizes the formation of channels or passage ways through which any carbon dioxide diffusing out of the oam may pass to the environment.

The insulation panel of this invention can be that of, for example, a refrigeration appliance unit or a boiler housing. Such a panel generally comprises a first wall; a second wall; and a body of foamed-in-place cellular insulation material therebetween. The manufacture of such a panel can be accomplished in that the second wall, optionally molded thermally and/or by pressure into a desired configuration, is brought into proximity of the first wall. The two walls are held in a spaced relationship while the insulating material is introduced by a foam-in-place operation. The method of construction of a refrigeration appliance unit in such a manner is disclosed in, for example, U.S. Patents 3,960,631; 4,196,950; 4,505,919 and 4,707,401.

For the present invention, the individual components are described in more detail as follows. The First Wall o The first wall may be, for example, a metal sheet or foil, wood, a synthetic resin optionally the same as that of the second wall, and optionally in combination with a barrier film. The Second Wall

The second wall is a thermoplastic synthetic resin sheet defining a first surface portion and having applied to said surface a barrier film which consists essentially of a thermoplastic polyester resin. The barrier film is applied to the surface of the synthetic resin sheet that would normally come into contact with the insulation material. Optionally, the barrier film may also be applied to other remaining surfaces of the synthetic resin sheet when it is desirable to benefit from additional properties offered by the presence of the film such as, o for example, surface gloss. The synthetic resin sheet of the second wall comprises a thermoplastic styrenic resin. Preferred styrenic resins are acrylonitrile-butadiene-styrene (ABS) copolymers and high impact polystyrene (HIPS) polymers. Such resins are preferred because they offer some inherent environmental stress crack resistance and primarily have good moldability. The ABS copolymer resins sheets that can be used in this present invention are well known to those skilled in the art, the preparation of which is disclosed in, for example, U.S. Patents 3,563,845; 3,565,746; 3,509,237; 4,959,434 and 5,244,946. Exemplary of the preferred styrenic polymers are those commercially available from The Dow Chemical Company and include the ABS resins such as MAGNUM'" 3404, MAGNUM'" 3303, and MAGNUM'" 9042 and the high impact polystyrene resins such as STYRON'" 469 and STYRON'" 5469. The relative 0 amount of the thermoplastic synthetic resin sheet to the barrier film can be conveniently expressed as a percentage thickness of the total thickness of the synthetic resin sheet and barrier film. Advantageously the barrier film constitutes at least 0.1, preferably at least 0.5, and more preferably at least 1 percent; and up to 20, preferably up to 10, more preferably up to 5 percent of the total thickness. 5 The Barrier Film

For the insulation panel, the barrier film is present in a thickness sufficient to minimize or substantially retard or prevent the diffusion loss of carbon dioxide from the polyurethane foam. The thickness of barrier film present is less than 150, preferably 50 or less, more preferably less than 45, and yet more preferably less than 30; but advantageously is at least 2, and more advantageously at least 5 microns. In a preferred embodiment, the barrier film has a thickness of from 5 to 50 microns, and preferably from 5 and up to less than 30 microns. The barrier film used in this present invention consists essentially of a homo- or co-polymer adduct of an aromatic dicarboxylic acid reacted with an active hydrogen- containing compound, such adducts are commonly referred to as polyester polymers or resins. Homopolyester polymers are derived from the reaction of one acid compound with one active hydrogen-containing compound. Copolyester polymers are derived from the reaction of at o least two active hydrogen-containing compounds with one acid compound or inversely two acid compounds with one active hydrogen-containing compound. Such copolyester polymer resins are frequently described as "glycol-modified" or "acid-modified" copolyesters, respectively. The acid compound may be an aliphatic, alicyclic or aromatic polyacid compound, preferably a diacid compound. More preferably, such a diacid compound is an aromatic dicarboxylic acid such as, for example, isophthalic acid, terephthalic acid, chloroterephthalic acid, methylterephthalic acid, or 4,4'-biphenyldicarboxylic acid. Preferred for this present invention are polyester polymers prepared from mono-aromatic dicarboxylic acids including isophthalic acid and especially terephthalic acid, or mixtures thereof. The active hydrogen- -containing adduct generally employed in the preparation of polyester resins is a polyhydroxyl 0 compound. Advantageously, to provide the resin with thermoplastic properties, such a hydroxyl compound contains a molar average of two hydroxyl groups. Exemplary of such hydroxyl compounds are the glycols including, for example, ethylene glycol, tetramethylene glycol, 1,4-cyclohexanedimethanol, dipropylene glycol, tripropylene glycol and aromatic dihydroxyl compounds such as, for example, bis-hydroxylphenyi compounds including 5 2,2-bis(4-hydroxyphenyl)propane. Pre erred thermoplastic polyester resins for use in this present invention are those homopolymers and copolymers which are obtained by reaction of glycols, especially ethylene glycol or tetramethylene glycol, and cyclohexanedimethanol or mixtures thereof with the preferred aromatic dicarboxylic acids. Suitable thermoplastic polyester resins can be obtained by conventional preparation procedures such as disclosed in 0 U.S. Patents 2,597,643; 3,740,371; 4,018,738; 4,034,016 and especially 4,474,918; 4,552,948; 4,565,851 and 4,578,437. Available commercially, and especially preferred for use in this present invention are the copolyester resins, especially the glycol-modified polyethylene terephthalate (PETG) resins such as, for example, KODAR'" PETG-6763 sold by Eastman Chemical Products Inc. Such copolyester resins have a greater tendency to be amorphous 5 polymers, thereby having wider molding and extrusion process latitudes of value when preparing thin films.

The barrier film may be laminated to the synthetic resin sheet by utilizing the inherent heat of extrusion of the synthetic resin sheet and a pressure application therebetween such as by suitable pressure rolls. Alternatively, the surface of the barrier film or the synthetic resin may be treated, preferably electrostatically, to promote adhesion of the film to the sheet. In a less preferred embodiment, the barrier film may be held to the synthetic resin by a tie layer, though preferably such a tie layer is absent. It is observed that a better carbon dioxide diffusion barrier performance, as evidenced by retention of thermal insulation properties, is found when the barrier film exhibits greater adhesion to the polyurethane foam than to the synthetic resin. Examples of suitable materials for the tie layer includes ABS copolymer, containing from 5 to 20 weight percent of acrylonitrile, or ethylene vinyl acetate.

Techniques involving coextrusion of the synthetic resin and barrier film may also o be employed to prepare the composite liner material. Techniques of applying a film by lamination to, or coextrusion with a synthetic resin sheet are well known to those skilled in the art of producing composite materials. Such techniques for the application of film are disclosed in, for example U.S. Patents 3,960,631; 4,005,919; 4,707,401 and 4,196,950. The Cellular Insulation Material The insulation material used in this invention is a closed-celled, or open-celled, cellular polyurethane polymer. Such material advantageously has a high thermal resistance, and a high compressive strength sufficient to contribute to the benefit of overall structural strength of the wall. As the configuration and geometry of the first and second walls may vary, construction of the cabinet wall is facilitated if the insulation can be prepared by a foam-in- 0 place procedure.

The polyurethane polymer can be prepared by mixing intimately under suitable reaction conditions an organic polyisocyanate with a polyahl, in the presence of an expanding agent, and introducing the foam-forming mixture into the space between the first and second walls. Advantageously the expanding agent is employed in quantities sufficient to provide for 5 a foam advantageously having an overall bulk density of from 10 to 200, preferably 15 to 100, and more preferably 18 to 60 kg/m³.

In the present invention, the expanding agent consists substantially of carbon dioxide optionally with a physical blowing agent. By the term "substantially", it is understood that more than 50 mole percent of the total expanding agent comprises carbon dioxide. The 0 expanding agent, based on total molar amounts of carbon dioxide and optional physical blowing agent present, preferably contains from at least 80 to 100, and more preferably from at least 90 to 100 mole percent of carbon dioxide; with preferably from 0 to less than 20, and more preferably rom 0 to less than 10 mole percent of a physical blowing agent. In a highly preferred embodiment the expanding agent consists of carbon dioxide. 5 Carbon dioxide, liquefied or gaseous, may be introduced, when reacting the organic polyisocyanate with polyahl, either when mixing the reactants or alternatively by prior mixing with one or more of the reactant streams. Alternatively, the carbon dioxide may be generated in situ while preparing the polyurethane. Carbon dioxide can be generated in situ by the chemical reaction of polyisocyanate with water, as may be present when preparing the polyurethane. Carbon dioxide can also be generated in situ by the thermal decomposition of a substance known to give carbon dioxide. The exotherm of the polyurethane formation reaction being suf icient to thermally decompose such substances including, for example, ammonium carbonate and the amine/carbon dioxide complexes such as described in

U.S. Patents 4,500,656 and 4,735,970. It is preferred to use carbon dioxide generated by an in situ procedure and especially by the polyisocyanate/water reaction. For this purpose, water is present in an amount of from 1 to 10, preferably from 2 to 8, and more preferably from 3 to 7 parts by weight per 100 parts by weight of polyahl. When the expanding agent also contains a physical blowing agent, such agents are generally organic compounds having an atmospheric boiling point of from -50°C to + 100°C at 760 mm/Hg. Suitable physical blowing agents include aliphatic or cycloaliphatic C₃ to C₈ alkanes, polyf luorinated alkanes including perfluorinated alkanes, or polyf luorinated ethers including perfluorinated ethers. Exemplary and preferred are aliphatic or cycloaliphatic alkanes including pentane, hexane, (methyl)cyclopentane, or cyclohexane or mixtures of two or more such blowing agents. In the present invention, when the barrier film has a thickness of less than 50 microns, physical blowing agents comprising a (hydro)chlorofluoro-, a hydrochloro-, a (hydro)bromof luoro-, or a hydrobromo-alkane are advantageously absent; as these agents may undesirably attack the synthetic resin sheet of the second wall leading eventually to mechanical failure.

The polyahls which are useful in the preparation of the polyurethane foam include those materials having two or more groups which contain an active hydrogen atoms which can react with an isocyanate, such as are described in U.S. Patent 4,394,491. Preferred among such polyahl compounds are those having at least two hydroxyl, primary or secondary amine, carboxylic acid, or thiol groups per molecule. Polyols, that is, compounds having at least two hydroxyl groups per molecule, are especially preferred due to their desirable reactivity with polyisocyanates.

Suitable polyahls for preparing rigid polyurethanes include polyether polyols, polyester polyols, polyhydroxyl-terminated acetal resins, hydroxyl-terminated amines and polyamines having an equivalent weight of 50 to 700, pre erably 70 to 300 and more pre erably 70 to 150. Such isocyanate-reactive materials also advantageously have a functionality of at least 2, preferably 3, up to 16, preferably up to 8. Examples of these and other suitable isocyanate-reactive materials are described more fully in U.S. Patent 4,394,491, particularly in columns 3-5 thereof. Most preferred for preparing rigid foams, on the basis of performance, availability and cost is a polyether or polyester polyol having from 2 to 8, preferably 3 to 8 active hydrogen atoms per molecule. Exemplary of such polyether polyols include those commercially available under the trademark VORANOL™ such as VORANOL 202, VORANOL'" 360, VORANOL 370, VORANOL'" 446, VORANOL'" 490, VORANOL'" 575, VORANOL'" 800 all sold by The Dow Chemical Company, and PLURACOL" 824, sold by BASF Wyandotte.

Polyisocyanates which are suitable for use in the practice of the present invention in making polyurethanes include aromatic, aliphatic and cycloaliphatic polyisocyanates and combinations thereof. Representative of these types are diisocyanates such as m- or p-phenylene diisocyanate, toluene-2,4-diisocyanate, toluene-2,6-diisocyanate, hexamethylene- -1,6-diisocyanate, tetramethylene-1,4-diisocyanate, cyclohexane-1,4-diisocyanate, hexahydrotoluene diisocyanate (and isomers), naphthylene-1,5-diisocyanate, 1-methylphenyl- -2,4-phenyldiisocyanate, diphenylmethane-4,4'-diisocyanate, diphenylmethane-2,4'- -diisocyanate, 4,4'-biphenylenediisocyanate, 3,3'-dimethoxy-4,4'-biphenylenediisocyanate and 3,3'-dimethyidiphenyipropane-4,4'-diisocyanate; triisocyanates such as toluene-2,4,6-tri- isocyanate and polyisocyanates such as4,4'-dimethyldiphenylmethane-2,2',5',5'-tetra- isocyanate and the diverse polymethylene polyphenylpolyisocyanates. A crude polyisocyanate may also be used in the practice of this invention, such as the crude toluene diisocyanate obtained by the phosgenation of a mixture of toluene diamines or the crude diphenylmethane diisocyanate obtained by the phosgenation of crude diphenylmethanediamine. Especially preferred are methylene-bridged polyphenylpolyisocyanates, due to their ability to crosslink the polyurethane.

In addition to the foregoing critical components, it is often desirable to employ certain other ingredients in preparing cellular polyurethane. Such additional ingredients include catalyst, surfactant, flame retardant, preservative, colorant, antioxidants, reinforcing agent, and fillers. When desiring to prepare an open-celled foam advantageously a cell opening agent may be present. Such cell opening agents and techniques for preparing an open celled foam are described in the open literature and various patent publications including, for example, U.S. Patents 5,284,882; 5,350,777; 5,318,997; 5,248,704; and 3,694,385; G.B. 1102,391; G.B. 1,065,590; EP-622.388-A; EP-610/734-A; EP-547.515-A; and EP-A-188,806.

When preparing the polyurethane foam, it is generally highly preferable to employ a minor amount of a surfactant to stabilize the foaming reaction mixture until it cures. Such surfactants advantageously comprise a liquid or solid organosilicone surfactant. Other, less preferred surfactants, include polyethylene glycol ethers of long chain alcohols, tertiary amine or alkanolamine salts of long chain alkyl acid sulfate esters, alkyl sulfonic esters and alkyl arylsulfonic acids. Such surfactants are employed in amounts sufficient to stabilize the foaming reaction mixture against collapse and the formation of large, uneven cells. Typically, 0.2 to 5 parts of the surfactant per 100 parts by total weight active hydrogen-containing compound(s) present are generally sufficient for this purpose.

One or more catalysts for the reaction of the active hydrogen-containing compound(s) with the polyisocyanate are advantageously used. Any suitable urethane catalyst may be used, including tertiary amine compounds and organometallic compounds. Exemplary tertiary amine compounds include triethylenediamine, N-methyl morpholine, pentamethyldiethylenetriamine, tetramethylethylenediamine, 1-methyl-4-dimethylamino- ethylpiperazine, 3-methoxy-N-diethyipropylamine, N-ethyl morpholine, diethylethanolamine, N-coco morpholine, N,N-dimethyl-N',N'-dimethyl isopropylpropylenediamine, N,N-diethyl-3- -diethylaminopropylamine, dimethylbenzylamine, or dimethylcyclohexylamine. Exemplary organometallic catalysts include organomercury, organolead, organoferric and organotin catalysts, with organotin catalysts being preferred among these. Suitable tin catalysts include stannous chloride, tin salts of carboxylic acids such as dibutyltin di-2-ethyl hexanoate, as well as other organometallic compounds such as are disclosed in U.S. Patent 2,846,408. A catalyst for o the trimerization of polyisocyanates, such as an alkali metal alkoxide, may also optionally be employed herein. Such catalysts are used in an amount which measurably increases the rate of reaction of the polyisocyanate. Typical amounts are 0.001 to 1 parts of catalyst per 100 parts by total weight of polyahl(s) present.

In making a polyurethane foam, the polyahl(s), polyisocyanate and other 5 components, including water, are contacted, thoroughly mixed and permitted to react and to expand and cure into a cellular polymer. The isocyanate index (ratio of equivalents of isocyanate to equivalents of active hydrogen-containing groups, including water as may be present) is advantageously from 0.9 to 5.0, preferably 0.9 to 3.0, more preferably 1.0 to 1.5. The particular mixing apparatus is not critical, and various types of mixing head and spray 0 apparatus are conveniently used. It is often convenient, but not necessary, to preblend certain of the raw materials prior to reacting the polyisocyanate and active hydrogen-containing components. For example, it is often useful to blend the polyahl(s), water, surfactants, catalysts and other components except for polyisocyanates, and then contact this mixture with the polyisocyanate. Alternatively, all components can be introduced individually to the mixing 5 zone where the polyisocyanate and polyol(s) are contacted. It is also possible to prereact all or a portion of the active hydrogen-containing compound(s) with the polyisocyanate to orm a prepolymer, although such is not preferred.

The following examples are given to illustrate the invention. Unless stated otherwise, all parts and percentages are given by weight. 0 Example 1

Shaped inner liner 1, suitable for preparing a refrigeration appliance unit, is obtained by thermal molding of a high impact polystyrene resin (HIPS), STYRON" 469, having a barrier ilm applied to one of its surfaces. The barrier film is a polyester resin, KODAR'"-PETG- -6373 present at 10 percent of the total thickness of the liner. After the thermal molding, the 5 barrier film has a thickness of respectively 50 microns. Shaped inner liner 2 is similarly prepared wherein the barrier film is 5 percent of the total thickness of the liner. After thermal molding, the barrier film has a thickness of 25 microns. As comparative to the polyester film, a coextruded film comprising polyethylene, ethylene vinyl alcohol, and polyvinylidene chloride polymers sold under the trademark SARANEX" by The Dow Chemical Company is applied to the same high impact polystyrene resin.

Insulation panels 1 and 2 are prepared in accordance with the general procedure of U.S. Patent 4,707,401 using shaped inner liners 1 and 2, respectively, and a closed-celled polyurethane foam having a molded density of 32 kg/m³- expanded by carbon dioxide and prepared by a foam-in-situ procedure.

The polyurethane foam is prepared by mixing under high pressure foaming conditions components as indicated below:

32 pbw a sorbitol-initiated oxypropylene adduct having a hydroxyl number of 482;

64 pbw a glycerine- initiated oxypropylene adduct having a hydroxyl number of

168;

4 pbw Water;

1.2 pbw TEGOSTAB^* B8427, a proprietary silicon-based surfactant available from Th. Goldschmidt AG;

1.7 pbw Amine catalyst; with a crude methylene diphenylisocyanate, VORANATE'" M220 available from The Dow

Chemical Company, present in an amount to provide an isocyanate reaction index of 120.

Comparative insulation panels A to C are similarly prepared except that Comparative panel A has SARANEX'" as the barrier film and Comparative panels B and C do not contain a barrier film. Comparative panel C also does not include the HIPS second wall.

The resulting panels are allowed to age at room temperature and the thermal conductivity performance of the polyurethane foam periodically observed according to the standard test procedure DIN 52612. To ensure that any aging, changes in thermal conductivity, of the polyurethane foam is associated with the performance of the barrier film, all faces of the foam with the exception of the face in contact with barrier film are made airtight. Just prior to measuring the thermal conductivity performance all facing material including barrier film is removed to completely expose the polyurethane foam.

The performance data reported in Table I clearly indicates the advantageous thermal insulation performance with time, as evidenced by the lower thermal conductivity of the polyurethane foam of Panels 1 and 2, to be obtained when PETG is selected as barrier film. Table I

Thermal conductivity (mW/m-k)

HIPS yes yes yes yes no

Barrier Film -1 yes / / / /

Barrier Film -2 / yes / / /

Barrier Film -3 / / yes / /

Days: 0 22 22 22 22 22

1 22 22.2 22.3 22.5 23.3

16 23.3 23.6 23.2 24.5 26

31 / / / 27.8 /

32 / / 26.3 / 29

34 24J 24.6 / / /

64 25.3 26.4 / 30.3 30.9

84 / / 30.3 1 /

128 26.8 28J 30.9 30.8 31.2

'Not an example of this invention

Barrier Film 1 : PETG, 50 microns

Barrier Film 2: PETG, 25 microns

Barrier Film 3: SARANEX, 50 microns. Example 2

In this example, insulation panels comprising an open-celled polyurethane foam are prepared and tested according to the general procedure of Example 1. The polyurethane foam is prepared according to the formulation as given for Example 1 but additionally in the presence of one part by weight of a cell opening agent. The cell opening agent is a particulate poly(tetraf luoroethylene) resin as more fully described in U.S. Patent 5,312,846.

The performance data reported in Table II clearly indicates the advantageous thermal insulation performance with time, as evidenced by the lower increase of the thermal conductivity of the polyurethane foam of Panels 3 to 5. Table II Increase in Thermal conductivity (mW/πrvk)

D*

HIPS yes yes yes yes

Barrier Film -3 yes / / /

Barrier Film -4 / yes / /

Barrier Film -5 / / yes /

Days: 0 / / / /

Days: 90 0.62 0.79 0.93 2.56

Days: 180 1.22 1.54 1.79 4.55

Days: 270 1.8 2.24 2.59 6J 5

'Not an example of this invention

Barrier Film 3: PETG, 100 microns Barrier Film 4: PETG, 50 microns Barrier Film 5: PETG, 25 microns

Claims

WHAT IS CLAIMED IS:

1. An insulation panel which comprises, a) a first wall element; b) a second wall element being a synthetic resin; c) a foamed-in-situ polyurethane foam, obtained by reacting a polyisocyanate with a polyahl in the presence of an expanding agent, contiguous to said first wall element and positioned between said first wall element and said second wall element; and d) a barrier film being a thermoplastic polyester resin interposed between said foamed-in-situ polyurethane foam and said second wall element, characterized in that: i) the expanding agent consists substantially of carbon dioxide; and ii) the thermoplastic polyester resin is a homo- or co-polymer adduct of an aromatic dicarboxylic acid and an active hydrogen-containing material.

2. A panel as claimed in Claim 1 wherein the barrier film has a thickness of from 5 to 50 microns.

3. A panel as claimed in Claim 2 wherein the barrier film has a thickness of less than 30 microns, but at least 5 microns.

4. A panel as claimed in Claim 1 wherein the carbon dioxide is generated in situ by the chemical reaction of polyisocyanate with water as present when preparing the polyurethane foam.

5. A panel as claimed in Claim 1 wherein the carbon dioxide is generated in situ by the thermal decomposition of a substance being a carbon dioxide source and which is present when preparing the polyurethane foam.

6. A panel as claimed in Claim 1 wherein the expanding agent may additionally consist of a physical blowing agent which includes an aliphatic or cycloaliphatic C3 to C₈ alkane, or a perfluorinated alkane having a boiling point of less than 100°C at 760 mm/Hg.

7. A panel as claimed in Claim 6 wherein the expanding agent consists, based on total molar amounts of (a) and (b), of: a) from at least 80 to 100 mole percent of carbon dioxide; and b) from 0 to less than 20 mole percent of a physical blowing agent.

8. A panel as claimed in Claims 1 to 7 wherein the thermoplastic polyester resin is an adduct of an aromatic dicarboxylic acid comprises terephthalic acid, isophthalic acid or mixtures thereof.

9. A panel as claimed in Claim 8 wherein the thermoplastic polyester resin is a polyethyleneterephthalate resin or a glycol-modified polyethyleneterephthalate resin.

10. A panel as claimed in Claims 1 to 7 wherein the thermoplastic styrenic resin is a high. impact polystyrene resin or an acrylonitrile-butadiene-styrene copolymer resin. 1. An insulation panel which comprises, a) a first wall element; b) a second wall element being a synthetic resin; c) a foamed-in-situ polyurethane foam, obtained by reacting a polyisocyanate with a polyahl in the presence of an expanding agent, contiguous to said first wall element and positioned between said first wall element and said second wall element; and d) a barrier film being a thermoplastic polyester resin which is interposed between said foamed-in-situ polyurethane foam and said second wall element, characterized in that: i) the expanding agent consists of carbon dioxide; ii) the barrier film has a thickness of less than 50, but at least 5 microns; and iii) the thermoplastic polyester resin, used as barrier film, is a polyethyleneterephthalate resin or a glycol-modified polyethyleneterephthalate resin.