WO2002002664A1

WO2002002664A1 - Process for making hydrocarbon-blown or hydrofluorocarbon-blown rigid polyurethane foams

Info

Publication number: WO2002002664A1
Application number: PCT/EP2001/005727
Authority: WO
Inventors: Lieve Sylvia Josepha Vanoverloop; Hilde Maenderveld
Original assignee: Huntsman International Llc
Priority date: 2000-07-04
Filing date: 2001-05-18
Publication date: 2002-01-10
Also published as: AU2001260317A1

Abstract

The invention provides an isocyanate-reactive composition comprising an amine-initiated polyol, where the amine is an aliphatic amine having a functionality of at least 4, for improving the hydro(fluoro)carbon blowing agent solubility. The invention also provides a process for the manufacture of a rigid polyurethane or urethane-modified polyisocyanurate foam comprising reacting the above composition with a polyisocyanate.

Description

DESCRIPTION

PROCESS FOR MAKING HYDROCARBON-BLOWN OR HYDROFLUOROCARBON-BLOWN RIGID POLYURETHANE FOAMS

This invention relates to processes for the preparation of rigid polyurethane or urethane- modified polyisocyanurate foams, to foams prepared thereby, and to novel compositions useful in the process.

Rigid polyurethane and urethane-modified polyisocyanurate foams are in general prepared by reacting the appropriate polyisocyanate and isocyanate-reactive compound (usually a polyol) in the presence of a blowing agent. One use of such foams is as a thermal insulation medium as for example in the construction of refrigerated storage devices. The thermal insulating properties of rigid foams are dependent upon a number of factors including, for closed cell rigid foams, the cell size and the thermal conductivity of the contents of the cells.

A class of materials which has been widely used as blowing agent in the production of polyurethane and urethane-modified polyisocyanurate foams are the fully halogenated chlorofluorocarbons, and in particular trichlorofluoromethane (CFC 11). The exceptionally low thermal conductivity of these blowing agents, and in particular of CFC 11, has enabled the preparation of rigid foams having very effective insulation properties. Recent concern over the potential of chlorofluorocarbons to cause depletion of ozone in the atmosphere has led to an urgent need to develop reaction systems in which chlorofluorocarbon blowing agents are replaced by alternative materials which are environmentally acceptable and which also produce foams having the necessary properties for the many applications in which they are used.

Such alternative blowing agents proposed in the prior art include hydrocarbons namely alkanes and cycloalkanes such as n-pentane, isopentane, cyclopentane and mixtures thereof. Other alternative blowing agents include hydrofluorocarbons (HFC) such as HFC 134a and HFC 245fa and mixtures thereof.

The problem with such blowing agents is that they are poorly soluble in the polyol compositions used for the manufacture of the rigid polyurethane foams. By using low hydroxyl value polyols as base polyols, the solubility is increased but at the same time detrimentally affecting the insulation and other physical properties of the obtained rigid polyurethane foams. Also, the solubility of such blowing agents is affected by the presence of water as (co)blowing agent, even in low amounts. This renders these blowing agents difficult to use in combination with water, although water is in many applications a desired chemical blowing agent.

There is thus a need towards polyol compositions having high functionality, high solubility for hydrocarbon and/or hydrofluorocarbon blowing agents, especially in combination with water, while at the same time providing foams with very good insulating and physical properties.

Improvements in hydrocarbon and/or hydrofluorocarbon solubility have been the subject of many patent applications.

WO-A-94/03515 discloses a process for the manufacture of polyurethane foams, in the presence of a blowing agent comprised of hydrocarbon or hydrofluorocarbon (e.g. HFC 134a), where the improvement consists in conducting the reaction in the further presence of a polyol initiated with an amine-type compound having a "tertiary amine group". Exemplary is triethanolamine (TELA) and ethylenediamine (EDA).

EP-A-477920 discloses a process for the manufacture of polyurethane foams, in the presence of a blowing agent comprised of hydrofluorocarbon (e.g. HFC 134a), where the improvement consists in conducting the reaction in the further presence of a nitrogen-containing compound. All examples in this patent application make however use of EDA-initiated polyol. EDA is the sole aliphatic amine exemplified in this patent application.

Further documents disclose amine-initiated polyol, where the amine is of higher functionality.

MOB AY patent US-P-4,230,824 discloses a sucrose-based polyol having a functionality of at least 6.5, in which a polyalkylenepolyamine such as diethylenetriamine (DETA) is used as the co-initiator. The polyol is indicated to have a functionality of at least 6.5 (i.e. the ratio sucrose:DETA is higher than 1:1). There is a minimum of information regarding the blowing agent used in the manufacture of polyurethane foams. The only blowing agent disclosed is

CFC 11, and consequently MOB AY necessarily failed to recognize the drastic improvements as regards hydrocarbon or hydrofluorocarbon solubility achieved in the present invention. MOBAY also necessarily failed to recognize that sucrose-DETA based polyols are also useful, despite functionalities below 6.5.

These objects are met by using in the process of making rigid polyurethane or urethane- modified polyisocyanurate foams from polyisocyanates and isocyanate-reactive components in the presence of hydrocarbon and/or hydrofluorocarbon blowing agents, a specific high functionality polyol, where this polyol comprises an amine-initiated polyol, where the amine is an aliphatic amine having a functionality above 4. This amine is preferably diethylenetriamine (DETA). This polyol can be mixed with another polyol, or it can be co- initiated, or both. It should be understood that amine-initiated thus covers the single initiated polyol as well as the co-initiated one.

The high functionality aliphatic amine comprises more than 4 reactive hydrogens, preferably from 5 to 8, especially 5. The amino groups are linked through aliphatic chains, which can be linear or branched, preferably linear, and where each chain comprises from 1 to 4 carbon atoms, preferably 1 to 2. Examples of such an aliphatic amine are diethylenetriamine (DETA), triethylene tetramine, tripropylene tetramine, tetra(hydroxyetlιyl)ethylene diamine.

The polyol as used in the invention generally has an OH value between 200 and 600 mg KOH/g, preferably between 250 and 500 mg KOH/g, and most preferably between 250 and 450 mg KOH/g.

Also, it is generally a polyoxyalkylene polyol, obtained by reacting an alkyleneoxide such as ethyleneoxide and/or propyleneoxide with the aliphatic amine initiator. Most preferably it is a polyoxypropylene polyol.

The instant invention is based on the surprising effect that this specific high functionality aliphatic amine-initiated polyol provides an improved solubility of hydrocarbon and/or hydrofluorocarbon blowing agents, even in the presence of water, while retaining very good, if not improving, insulating and physical properties, when compared to traditional amine-initiated polyol.

The fact that the solubility is hardly affected by the presence of water, especially for hydrofluorocarbon-blown foams, is quite surprising, since it is generally accepted in the art that water causes the solubility to drop (although the mechanism of action is not fully understood).

Besides improved solubility (both in the absence and presence of water), the high functionality aliphatic amine-initiated polyol used in the invention exhibits high functionality. High functionality is beneficial to the final foams, as it gives better strength (higher compression set) and is advantageous for the cell size. Other foam properties are either not affected or are improved. Especially, the polyol of the invention has a viscosity that allows processing without modifications of the existing equipment (which is traditionally associated with high functionality polyol). Besides the aliphatic amine-initiated polyol of the invention, other polyol(s) can be used. For example, a high functionality polyol is additionally used. This high functionality polyol (f_n from 5 to 8) can be sorbitol initiated or sucrose initiated. Other initiators known to the skilled man can be used.

Preferably, the invention provides two embodiments, which optionally can be combined.

According to the first preferred embodiment, the sucrose- or sorbitol-initiated polyol is mixed with the DETA-initiated polyol. These single-initiated polyols are manufactured according to standard procedures known to the skilled man.

According to the second preferred embodiment, either sucrose or sorbitol and DETA are present as initiator and co-initiator. This double-initiated polyol is then manufactured according to standard procedures known to the skilled man. For example, DETA is heated with propyleneoxide (PO) in the presence of potassium hydroxide as catalyst. The residual catalyst is subsequently neutralized with acetic acid.

The ratio sucrose or sorbitol to aliphatic amine (especially DETA) can vary within broad limits; this ratio can be comprised between 1:0.3 to 1:5.0, preferably between 1:0.6 to 1:3. Advantageously, the molar ratio sucrose: amine or sorbitol: amine (especially DETA) is below 1:1, most preferably between 1:1.5 and 1 :2.3.

Suitable organic polyisocyanates for use in the process of the present invention 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 diisocyanate in the form of its 2,4'-, 2,2'- and 4,4'-isomers and mixtures thereof, the mixtures of diphenylmethane diisocyanates (MDI) and oligomers thereof known in the art as "crude" or polymeric MDI (polymethylene polyphenylene polyisocyanates) having an isocyanate functionality of greater than 2, toluene diisocyanate in the form of its 2,4- and 2,6-isomers and mixtures thereof, 1,5-naphthalene diisocyanate and 1,4-diisocyanatobenzene. Other organic polyisocyanates, which may be mentioned, include the aliphatic diisocyanates such as isophorone diisocyanate, 1,6-diisocyanatohexane and 4,4'-diisocyanatodicyclohexylmethane. Further suitable polyisocyanates for use in the process of the invention are those described in EP-A-0320134.

Modified polyisocyanates, such as carbodiimide or uretonimine modified polyisocyanates can also be employed. Still other useful organic polyisocyanates are isocyanate-terminated prepolymers prepared by reacting an excess organic polyisocyanate with a minor amount of an active hydrogen- containing compound.

Preferred polyisocyanates to be used in the present invention are the polymeric MDI's.

As already indicated, further isocyanate-reactive compounds can be used in combination with the specific polyol(s) of the invention. These are those traditionally used in the art. In general, the amount of the high functionality aliphatic amine-initiated (or co-initiated) polyol ranges from 5 to 80% by weight, preferably from 10 to 50%, most preferably (especially for hydrocarbon-blown foam) from 11 to 20%, based on the weight of the isocyanate-reactive composition.

Suitable further isocyanate-reactive compounds to be used in the process of the present invention 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, triemanolamine, pentaerythritol, sorbitol and sucrose; polyamines, for example ethylene diamine, tolylene diamine (TDA), diaminodiphenylmethane (DADPM) and polymethylene polyphenylene polyamines; and aminoalcohols, for example ethanolamine 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, polyesteramides, polycarbonates, polyacetals, polyolefins and polysiloxanes.

The quantities of the polyisocyanate compositions and the polyfunctional isocyanate-reactive compositions (including the polyol(s) of the invention) 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. In general the NCO:OH ratio falls within the range 0.85 to 1.40, preferably 0.95 to 1.20. Also higher NCO:OH ratios (for example up to 3.0) fall within the invention. Suitable hydrocarbon blowing agents include lower aliphatic or cyclic, linear or branched hydrocarbons such as alkanes, alkenes and cycloalkanes, preferably having from 4 to 8 carbon atoms. Specific examples include n-butane, iso-butane, 2,3-dimethylbutane, cyclobutane, n- pentane, iso-pentane, teclinical grade pentane mixtures, cyclopentane, methylcyclopentane, neopentane, n-hexane, iso-hexane, n-heptane, iso-heptane, cyclohexane, methylcyclohexane, 1-pentene, 2-metl ylbutene, 3-methylbutene, 1-hexene and any mixture of the above. Preferred hydrocarbons are n-butane, iso-butane, cyclopentane, n-pentane and isopentane and any mixture thereof. A preferred mixture comprises cyclopentane and isopentane in ratio's varying between 30:70 to 80:20.

Suitable hydrofluorocarbon blowing agents include lower aliphatic or cyclic, linear or branched hydrocarbons such as alkanes, alkenes and cycloalkanes, preferably having from 2 to 8 carbon atoms, which are substituted with at least one, preferably at least three, fluorine atom(s). Specific examples include 1,1,1,2-tetrafluoroethane (HFC 134a), 1,1,2,2- tetrafluoroethane, trifluorometliane, heptafluoropropane, 1,1,1-trifluoroethane, 1,1,2- trifluoroethane, 1,1,1,2,2-pentafluoropropane, 1,1,1,3-tetrafluoropropane, 1,1,1,3,3- pentafluoropropane, 1,1,3,3,3-pentafluoropropane (HFC 245fa), 1,1, 1,3,3 -pentafluoro-n- butane (HFC 365mfc) and 1,1,1,4,4,4-hexafluoro-n-butane. The most preferred hydrofluorocarbon is HFC 134a.

Mixtures of hydrocarbon and hydrofluorocarbon blowing agents can be used as well. Examples hereof include mixtures of cyclopentane and HFC 134a, mixtures of cyclopentane and HFC 245fa, and mixtures of cyclopentane and HFC 365mfc. Preferably the amount of hydrofluorocarbon blowing agent in the mixture with hydrocarbon blowing agent is less than 50 wt%, most preferably between 2 and 30 wt%.

Other physical blowing agents known for the production of rigid polyurethane foam can be used together with the hydrocarbon and/or hydrofluorocarbon blowing agents in an amount of up to 80 wt%, even up to 90 % by weight of the total physical blowing agent mixture. Examples of these include dialkyl ethers, cycloalkylene ethers and ketones, fluorinated ethers, perfluorinated hydrocarbons, and hydrochlorofluorocarbons (e.g. l-chloro-l,2-difluoroethane, l-chloro-2,2-difluoroethane, l-chloro-l,l-difluoroethane, 1,1-dichloro-l-fluoroethane and monochlorodifluoromethane).

Generally water or other carbon dioxide-evolving compounds are also used together with the physical blowing agents. Where water is used as chemical co-blowing agent typical amounts are in the range from 0.2 to 5 %, preferably from 0.5 to 3 %, most preferably from 1.5 to 3 % by weight based on the isocyanate-reactive composition. 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. This quantity of blowing agent is in general such that the resulting foam has the desired bulk density which is generally in the range of 15 to 70 kg/m³, preferably 20 to 50 kg/m³, most preferably 25 to 40 kg/m³.

When expressed per hundred parts of isocyanate-reactive composition, the amount of hydrocarbon and/or hydrofluorocarbon blowing agent can be comprised between 1 and 20 %, preferably between 3 and 15 % by weight.

When a blowing agent has a boiling point at or below ambient it is maintained under pressure until it is mixed with the other components. Alternatively, it can be maintained at subambient temperatures until mixed with the other components.

In addition to the polyisocyanate and polyfunctional isocyanate-reactive compositions and the blowing agents, the foam-forming reaction mixture will commonly contain one or more other auxiliaries or additives conventional to formulations for the production of rigid polyurethane and urethane-modified polyisocyanurate foams. Such optional additives include crosslinking agents, for examples low molecular weight polyols such as triethanolamine, foam-stabilizing 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 triethylene diamine, isocyanurate catalysts, fire retardants, for example halogenated alkyl phosphates such as tris chloropropyl phosphate, fillers such as carbon black, cell size regulators such as insoluble fluorinated compounds. The use of such additives is well known to those skilled in the art.

In operating the process for making rigid foams according to the invention, the known one- shot, prepolymer or semi-prepolymer techniques may be used together with conventional mixing methods and the rigid foam may be produced in the form of slabstock, moldings, cavity fillings, sprayed foam, frothed foam or laminates with other materials such as hardboard, plasterboard, plastics, paper or metal.

It is convenient in many applications to provide the components for polyurethane production in pre-blended formulations based on each of the primary polyisocyanate and isocyanate- reactive components. In particular, many reaction systems employ a polyisocyanate-reactive composition, which contains the major additives such as the blowing agent and the catalyst in addition to the polyisocyanate-reactive component or components. Therefore the present invention also provides a polyisocyanate-reactive composition comprising the present mixture of the specific polyol(s) and the hydro(fluoro)carbon blowing agent.

The various aspects of this invention are illustrated, but not limited by the following examples.

The following reaction components are referred to in the examples:

Polyol 1 : sucrose single initiated polyol, 25 mole of PO per mole of sucrose, OH value is 250 mg KOH/g.

Polyol 2: sucrose single initiated polyol, 16.9 mole of PO per mole of sucrose, OH value is 350 mg KOH/g. Polyol 3: sucrose single initiated polyol, 9.6 mole of PO per mole of sucrose, OH value is 500 mg KOH/g. Polyol 4: DETA single initiated polyol, 8.8 mole of PO per mole of DETA, OH value is 500 mg KOH/g. Polyol 5: DETA single initiated polyol, 12.1 mole of PO per mole of DETA, OH value is 350 mg KOH/g. Polyol 6: DETA single initiated polyol, 18 mole of PO per mole of DETA, OH value is 250 mg KOH/g.

Polyol 7: EDA single initiated polyol, 6.7 mole of PO per mole of EDA, OH value is 500 mg KOH/g. Polyol 8 is a polyol of OH value of 350 mg KOH/g, of functionality 6.0, resulting from the mixture of Polyol 2 and Polyol 5 at a ratio of 1 :2. Polyol 10: Aromatic polyether polyol of OH value 500 mg KOH/g, available from

Huntsman Polyurethanes. Polyol 11: Aromatic polyether polyol of OH value 310 mg KOH/g, available from

Huntsman Polyurethanes. Polyol 12: Sugar-based polyether polyol of OH value 460 mg KOH/g, available from Huntsman Polyurethanes.

Polyol 13: EDA single initiated polyol, 9.5 mole of PO per mole of EDA, OH value is 350 mg KOH/g. Polyol 14: sorbitol initiated polyol, 14 mole of PO per mole of sorbitol, OH value is

350 mg KOH/g. Isocyanate: Polymeric MDI with a NCO value of 30.7%, available from Huntsman

Polyurethanes under the name SUPRASEC DNR (SUPRASEC is a trademark of Huntsman International LLC). Niax Al : Amine catalyst available from Union Carbide. SFC: Dimethylcyclohexylamine catalyst. B 8423: Silicone surfactant available from Goldschmidt.

Example 1: Hydrocarbon solubility.

Cyclopentane and isopentane solubilities are measured at 25°C, in dry polyol and in wet polyol (2% by weight of added water). OH values are 250, 350 and 500 mg KOH/g.

The following tables give the results. F_n is functionality. Solubility is expressed in pbw per 100 pbw of polyol or in pbw per 100 pbw of polyol plus 2 pbw of water.

Table 1: OH value 500 mg KOH/g.

Table 2: OH value 350 mg KOH/g.

Table 3: OH value 250 mg KOH/g.

The elements above show that the polyol of the invention provides a very high solubility of hydrocarbon, both under dry and wet conditions.

Example 2:Hydrocarbon solubility versus conventional amine-initiated polyols.

Example 1 has been reproduced, but this time with polyols that have been initiated with amines of a lower functionality, namely ethylenediamine (EDA). The results are provided in the following tables.

Table 4: OH value 500 mg KOH/g. Between parenthesis is given the values obtained for the corresponding DETA polyol

The polyol of the invention provides an improved solubility versus the aliphatic amine initiated polyols of the prior art. Example 3: Viscosities.

The following tables gives the viscosities at 25°C and 50°C, for various polyols, expressed in Poise.

Table 5: OH value 500 mg KOH/g.

Table 6: OH value 350 mg KOH/g.

Table 7: OH value 250 g KOH/g.

The elements above show that the polyol of the invention has a viscosity that allows processing under good conditions and without modifications of the existing equipment (which is traditionally associated with high functionality polyol).

The viscosity of the polyol of the present invention is lower than the viscosity of an EDA- initiated polyol of the same overall functionality.

A sucrose/DETA polyol of functionality 5.5 has a viscosity at 50°C of 19 Poise whereas a sucrose/EDA polyol of the same functionality has a viscosity at 50°C of 37 Poise.

Example 4: Substitution in existing foam, cyclopentane as the blowing agent.

In this example, the polyol of the invention (Polyol 8) is used in lieu of a traditional aromatic amine-initiated polyol. The foam is manufactured as follows.

All components of the polyol blend are weighed and poured into a bottle. The bottle is shaken to mix the chemicals thoroughly until homogeneous. Then the blowing agent is added and the bottle shaken again until homogeneous. The foam is prepared by weighing the exact amount of polyisocyanate into a cup. Add the required amount of polyol and mix for 5 seconds at a speed of 2500 rpm. The foam mix is then poured into a wooden open top mould (20x20x30cm) and left to cure.

The following table indicates the composition. Table 8.

The results are summarized in the next table. The various standards for measuring the characteristics are given below:

Reactivity ISO 845

Adhesion DIN 53292

Cell Size Method described in the Proceedings of the 35th

Annual Polyurethanes Technical Marketing Conference of October 9-12, 1994, page 369 under the title "The elimination of radiative heat transfer in fine celled PU rigid foam" by G. Eeckhout and A. Cunningham.

Closed Cell Content ASTM D2856 Compression strength DIN 53421 KK--vvaalluuee aatt 1100°°CC ISO 8301 Table 9.

The above indicates that the foams obtained with the polyol of the invention are improved vis-a-vis the comparative example, representing a common formulation. Example 5: HFC 134a solubility

Since HFC 134a is a low boiling agent with a boiling point of -26°C, the blowing agent had to be handled in pressurized bottles. These bottles were filled according to the procedure:

- add about 50 g of polyol in the bottle (inner volume 100ml);

- close the bottle with lid;

- weigh the bottle;

- add the required amount of HFC 134a;

- reweigh the bottle.

The bottle is then shaken by hand 1 min and then put on the rock-n-roller to further mix the blend for 24 hrs. During Hie 24 hrs on tl e rock-n-roller the blend is screened hourly for mixing lines. This gives the rate of solubility. When a lot of mixing lines were seen, a rating of 2 was given while a rating of 1 indicates that there is no mixing line. The pressure above the mixture indicates the HFC 134a solubility for various loadings (5 to 40% by weight). The pressure is measured above the liquid phase to determine the HFC 134a solubility. Dry and wet polyols are used (wet polyol is one with 2% water).

The polyols that were tested have a varying functionality, and an OH value of 250 or 350 mg KOH/g.

Table 10: OH value 350 mg KOH/g.

Table 11 : OH value 250 mg KOH/g.

For a polyol having a functionality of 5.50 (i.e. one mole of sucrose to 5 mole of DETA), the following table gives the solubility of HFC 134a, for dry and wet polyols, for varying OH values, and for a loading of 10%) of HFC 134a.

Table 12:

The elements above show that the polyol of the invention provides a very high solubility of hydrofluorocarbon, both under the dry and wet conditions.

Furthermore, for the polyol having a functionality of 5.5 as above, the solubility is also determined for varying OH values and for varying loadings of HFC 134a. The following table summarizes the results.

Table 13:

Contrary to prior art polyols the solubility does not vary much with the OH value of the aliphatic amine-initiated polyol of the invention. Last, it is worth noting that the solutions of the polyol of the invention together with HFC 134a are very stable over time. This allows for pre-blended systems (typically containing less than 5% of 134a) much faster production cycles.

The rate of solubility is also determined for the same polyol ^==5.50), for different loadings and different OH values.

- at OH value of 250 mg KOH/g, at 10% loading, the mix is immediately achieved. For loadings of 30% and 50%, one hour only is needed to achieve the mix.

- at OH value of 350 mg KOH/g, at 10% loading, the mix takes about 4 hours. For higher loadings of 30% and 50%, then the time needed is substantially lower. at OH value of 500 mg KOH/g, a behavior similar to the above is noted.

Froth has also been determined, in the above bottle. The polyol is the one having the functionality of 5.50 and an OH value of 350 mg KOH/g. HFC 134a is loaded at 5% by weight. The bottle is heavily shaken, then opened. Froth is determined immediately after opening. Neither the dry polyol nor the wet polyol (2%> water) did froth. This supports tlie remarkable behavior of the polyol of the invention, for both dry and wet conditions.

Example 6: Hydrofluorocarbon solubility versus conventional amine-initiated polyols.

Example 5 has been reproduced, but this time with polyols that have been initiated with amines of a lower functionality, namely ethylenediamine (EDA). The results are provided in the following tables.

For a polyol having a functionality of 5.50 (i.e. one mole of sucrose to 1.65 mole of EDA), the following table gives the solubility of HFC 134a, for wet polyols, for varying OH values, and for varying loadings of HFC 134a.

Table 14: Between parenthesis are given the values obtained for the corresponding DETA polyol

The polyol of the invention provides an improved solubility versus the aliphatic amines of the prior art.

Example 7: Hydrofluorocarbon HFC 134a solubility.

Examples 5 and 6 are repeated, but this time with sorbitol initiated polyol in admixture with DETA-initiated polyol versus EDA-initiated polyol. The results are summarized in the following table for wet polyols.

Table 15: OH value 350 mg KOH/g.

Claims

1. An isocyanate-reactive composition comprising:

(a) at least an amine-initiated polyol, where the amine is an aliphatic amine having a functionality of at least 4;

(b) a blowing agent which is a hydrocarbon and/or a hydrofluorocarbon; and

(c) optionally water.

2. Composition according to claim 1, wherein the aliphatic amine having a functionality of at least 4 is diethylenetriamine.

3. Composition according to claim 1 or 2, wherein the hydrocarbon and/or hydrofluorocarbon blowing agent is used together with water.

4. Composition according to any one of claims 1 to 3, wherein the polyol has an OH value between 200 and 600 mg KOH/g, preferably between 250 and 500 mg KOH/g, and most preferably between 250 and 400 mg KOH/g.

5. Composition according to any one of claims 1 to 4, wherein the amine-initiated polyol is a polyoxyalkylene polyol, preferably a polyoxypropylene polyol.

6. Composition according to any one of claims 1 to 5, wherein the amine-initiated polyol represents from 5 to 80% by weight, preferably from 10 to 50%), based on the weight of the isocyanate-reactive composition.

7. Composition according to any one of claims 1 to 6, wherein the blowing agent represents from 1 to 20 %, preferably from 3 to 15 % by weight based on the isocyanate-reactive composition.

8. Composition according to any one of claims 3 to 7, wherein water represents from 0.2 to 5%, preferably from 0.5 to 3% by weight based on the isocyanate-reactive composition.

9. Composition according to any one of claims 1 to 8, wherein the composition further comprises a sucrose- or sorbitol-initiated polyol, which can optionally be co-initiated.

10. Composition according to claim 9, wherein the molar ratio sucrose:amine or sorbitol.-amine is below 1:1, preferably between 1:1.5 and 1:2.3.

11. Composition according to any one of claims 1 to 10, wherein the hydrocarbon blowing agent comprises cyclopentane.

12. Composition according to any one of claims 1 to 11, wherein the hydrofluorocarbon blowing agent comprises HFC 134a or HFC 245fa.

13. A polyol composition comprising:

(b) at least a sucrose- or sorbitol-initiated polyol, which can optionally be co-initiated; and in which the molar ratio sucrose: amine or sorbitol: amine is below 1:1, preferably between 1 :1.5 and 1 :2.3.

14. Polyol composition according to claim 13, wherein the aliphatic amine having a functionality of at least 4 is diethylenetriamine.

15. Polyol composition according to claim 13 or 14, wherein the polyol(s) has(have) an OH value between 200 and 600 mg KOH/g, preferably between 250 and 500 mg KOH/g, and most preferably between 250 and 400 mg KOH/g.

16. Polyol composition according to any one of claims 13 to 15, wherein the polyol(s) is(are) a polyoxyalkylene polyol, preferably a polyoxypropylene polyol.

17. A process for making a rigid polyurethane or urethane-modified polyisocyanurate foam comprising reacting at least one polyisocyanate with the composition as defined in any one of claims 1 to 12.

18. A process for making a rigid polyurethane or urethane-modified polyisocyanurate foam comprising reacting at least one polyisocyanate with the polyol composition as defined in any one of claims 13 to 16, in the presence of a physical and/or chemical blowing agent.

19. Rigid polyurethane or urethane-modified polyisocyanurate foams obtainable by the process as defined in claims 17 or 18.

0. Use of an amine-initiated polyol for increasing the hydrocarbon and/or hydrofluorocarbon solubility in an isocyanate-reactive composition, where the amine is an aliphatic amine having a functionality of at least 4.