FR2852962A1 - Manufacturing foams for making supported foam, by reacting polyol(s) with isocyanate(s) in presence of catalyst, polyepoxide, blowing agent other than chlorofluorocarbon and/or flammable blowing agent - Google Patents

Abstract

Manufacturing foams comprises reacting polyol(s) with isocyanate(s) in the presence of catalyst, polyepoxide, blowing agent other than chlorofluorocarbon, and/or flammable blowing agent. The foams comprise (modified) polyurethane. The blowing agent other than chlorofluorocarbon is preferably hydro fluorocarbon.

Description

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Process for the production of polyurethane or modified polyurethane foams
The present invention relates to a process for the production of polyurethane foams or modified polyurethane foams, such foams and certain products suitable for use in the process.

 Due to concerns about the potential harmful effect on the stratospheric ozone layer of chlorofluorocarbons (CFCs) previously used as blowing agents in the manufacture of polyurethanes, the industry is led to use blowing agents other than CFCs.

 The change of swelling agent requires new formulations making it possible to economically produce polyurethane foams having satisfactory properties, in particular with regard to dimensional stability, adhesion to supports, thermal conductivity and fire resistance. In particular, it should be noted that chlorofluorocarbons have a specific effect to increase fire resistance, while this is generally not the case for the alternative blowing agents envisaged.

 Patent application US 2002/0019452 discloses in its example 4 that polyisocyanurate foams having a fire resistance of classification B2 can be obtained by using certain polyalkyleneoxydiols with known flame retardants and with CO 2 produced by in situ hydrolysis of isocyanate as a blowing agent.

 The invention aims to remedy the problems mentioned above.

 The invention therefore relates to a process for the manufacture of polyurethane or modified polyurethane foams in which at least one polyol is reacted with at least one isocyanate in the presence of a catalyst, a polyepoxide and a swelling agent. other than a chlorofluorocarbon, in particular an HFC and / or a flammable blowing agent.

 It has been found, surprisingly, that the method according to the invention makes it possible to obtain foams conforming to classification B2 with a wide range of blowing agents including flammable blowing agents. The foam obtained generally has a flame height when subjected to the test of DIN 4102 or EN ISO 11925-2 less than 15 cm (foam B2 or E). Often the foam obtained has a flame height

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 less than or equal to about 13 cm. It is even possible to produce a foam having a flame height less than or equal to about 10 cm.

The foams obtained have particularly good adhesion to substrates such as metals, walls, for example concrete, glass and wood. This effect also occurs when the surface of the support is not heated and is, for example, at a temperature less than or equal to about 20 C. The presence of the polyepoxide makes it possible to reduce the viscosity of the mixture of reagents.

 By polyurethane is meant the polymers resulting essentially from the reaction of polyols and isocyanates. These polymers are typically obtained from formulations having an isocyanate index of 100 to 180.

 By modified polyurethane is meant the polymers resulting from the reaction of polyols and isocyanates which contain, in addition to urethane functions, other types of functions, in particular triisocyanuric rings formed by trimerization of isocyanates. These modified polyurethanes are regularly called polyisocyanurates. These polymers are typically obtained from formulations having an isocyanate index of 180 to 450.

 All the isocyanates conventionally used to manufacture such foams can be used in the process according to the invention. By way of examples, there may be mentioned aliphatic isocyanates, such as hexamethylene diisocyanate and aromatic isocyanates, such as tolylene diisocyanate or diphenylmethane diisocyanate.

 For the purposes of the present invention, the term “polyol” means any compound containing at least two functional groups reacting with isocyanates. These functional groups contain at least one active hydrogen atom, as defined by the Zerewittinoff reaction. The active hydrogen atom is generally a hydrogen atom linked to an oxygen, nitrogen or sulfur atom. As polyol, the polyether polyols and polyester polyols can be used in the process according to the invention.

 In a preferred embodiment, the structure of the polyol is essentially free of phosphorus. Particular examples of polyether polyols can be obtained by reaction of alkylene oxides with an initiator compound containing at least 2 functional groups containing at least one active hydrogen atom, as defined above.

 Initiating compounds can be chosen, for example, from polyalcohols, polyamines, aminoalcohols and thioalcohols.

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 Among the polyalcohols, mention may in particular be made of ethylene glycol, glycerol, diethylene glycol, 2-butyne-1,4-diol, 2,3-dibromo-2-butene-1,4-diol, trimethylolpropane, triethanolamine , pentaerhytritol, sorbitol and sucrose.

 Among the polyamines, mention will be made in particular of diethanolamine, ethylenediamine, triethylenediamine, tolylenediamine and diaminodiphenylmethane.

 Among the amino alcohols, mention will be made in particular of ethanolamine and diethanolamine.

 Among the thioalcohols, mercaptoethanol will be mentioned in particular.

 Particular examples of polyether polyols can be obtained by condensation of polyols, in particular glycols with an initiator compound containing at least 2 carboxylic groups or by reaction of this initiator compound with ethylene oxide and / or the oxide propylene. Phthalic or terephthalic acid is preferred as the initiating carboxylic acid.

 The polyols are preferably free of phosphorus in their structure.

They may optionally contain halogens such as in particular chlorine and / or bromine. They can also be essentially halogen-free in their structure.

 In the process according to the invention, the catalyst can comprise a compound catalyzing the formation of the urethane-NH - CO - O- bond, by reaction between a polyol and an isocyanate or activating the reaction between an isocyanate and water, such than tertiary amines and organic compounds of tin, iron, mercury or lead. As tertiary amines, there may be mentioned in particular triethylamine, N, N-dimethylcyclohexylamine (DMCHA), N-methylmorpholine (NMM), N-ethylmorpholine, dimethylethanolamine, diaza [2.2.2] bicyclooctane (triethylenediamine) and substituted benzylamines such as N, N-dimethylbenzylamine (DB). As organic compounds of tin or lead, mention may in particular be made of dibutyltin dilaurate, stannous octanoate and lead octanoate.

 The catalyst can also, in particular when the manufacture of modified polyurethane foams (polyisocyanurates) is aimed at, comprise a compound catalyzing the trimerization of isocyanates into triisocyanurates. Specific examples of these catalysts are chosen from sterically hindered amines such as diazabicyclooctane and from ammonium salts. A mixture of several catalysts can be used.

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In the process according to the invention, the polyepoxide comprises at least 2 epoxy functionalities. Generally, the polyepoxide comprises at most 6 epoxy functionalities. When producing a polyurethane foam, the polyepoxide preferably comprises 5 or 6 epoxy functionalities. When a polyisocyanurate foam is produced, the polyepoxide preferably comprises 2 or 3 epoxy functional groups.

 In the process according to the invention, the polyepoxide generally comprises a number greater than or equal to 8 carbon atoms. Often the polyepoxide has a number greater than or equal to 11 carbon atoms. Preferably, the polyepoxide comprises a number greater than or equal to 13 carbon atoms.

 In the process according to the invention, the polyepoxide generally comprises a number less than or equal to 96 carbon atoms. Often the polyepoxide has a number less than or equal to 42 carbon atoms. Preferably, the polyepoxide comprises a number less than or equal to 20 carbon atoms.

 The polyepoxide may comprise certain substituents or functional groups such as in particular halogens, preferably chosen from chlorine and bromine, aromatic groups or triple or double bonds. In a particularly preferred manner, the polyepoxide comprises bromine or a triple bond.

 In a preferred embodiment, the polyepoxide is capable of being obtained by a reaction of epichlorohydrin with an initiator compound as described above containing at least 2 functional groups, each of the functional groups containing at least one active hydrogen atom .

 The initiator compounds generally comprise 2, 3, 4, 5 or 6 functional groups. Preferably, the initiator compound is chosen from polyalcohols, particularly preferably from polyalcohols described above. More preferably still more, it is chosen from 2butyne-1,4-diol and 2,3-dibromo-2-butene-1,4-diol.

 The polyalcohol can also be chosen from polyesterpolyols or polyetherpolyols as described above. In a particular embodiment, the polyalcohol is a polyester polyol capable of being obtained by reaction of phthalic acid or 3,4,5,6-tetrabromophthalic acid with approximately 2 equivalents of ethylene oxide and approximately 1 equivalent propylene oxide.

 In the preferred embodiment, the polyepoxide is generally obtainable by the reaction of the initiator compound with from 1 to 5

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 epichlorohydrin equivalents by functional group of the initiator compound.

 In a first particularly preferred variant, the polyepoxide is capable of being obtained by the reaction of the initiator compound with approximately 1 equivalent of epichlorohydrin per functional group.

 In a second particularly preferred variant, the polyepoxide is capable of being obtained by the reaction of the initiator compound with greater than or equal to approximately 1.2 equivalents, in particular with greater than or equal to approximately 1.25 equivalents of epichlorohydrin per functional group. In this variant, the polyepoxide is capable of being obtained by the reaction of the initiator compound with less than or equal to approximately 3 equivalents, in particular with less than or equal to approximately 2 equivalents of epichlorohydrin per functional group.

 It is understood that each of these variants can be combined with each of the above-mentioned initiating compounds.

 The polyepoxides can be obtained, for example, by the reaction of the initiating compounds with epichlorohydrin in the presence of a Lewis acid such as BF3.Et20 followed by cyclization in basic medium, in particular in the presence of a light excess of a strong base such as sodium hydroxide.

 The invention also relates to the polyepoxides in accordance with the description above.

 It has been found that the polyepoxides according to the invention have particularly good properties for reducing the viscosity of reaction mixtures in the process according to the invention and for increasing the solubility of the swelling agent in these mixtures.

 In the process according to the invention, the swelling agent is not a chlorofluorocarbon. It is understood that the blowing agent can be a mixture of several compounds. Suitable blowing agents are chosen, for example, from CO 2, which can be formed in situ by reaction of the isocyanate with water, hydrocarbons, ethers and ketones, optionally fluorinated, such as alkanes, hydrofluoroalkanes, hydrochlorofluoroalkanes, dialkyl ethers, and hydrofluoroethers.

 In a particular embodiment, a swelling agent comprising an HFC and / or a flammable compound is used. The term “flammable blowing agent” is intended to denote in particular a compound having a flash point according to standard ISO 1523.

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 It has been found, surprisingly, that the method according to the invention makes it possible to obtain foams meeting the classification B2 as described above even when a flammable blowing agent is used which increases the flammability of the foam.

 The flammable blowing agent preferably contains at least one compound chosen from hydrocarbons, in particular alkanes, alkyl ethers and hydrofluoroalkanes.

 As the hydrocarbon, a hydrocarbon, in particular an alkane, containing 5, 6 or 7 carbon atoms is often used. Particular examples of hydrocarbons are chosen from pentanes, hexanes such as n-hexane or isohexane and heptanes such as n-heptane. A pentane chosen in particular from n-pentane, isopentane, neopentane and cyclopentane is preferred. N-pentane is very particularly preferred.

 As hydrofluoroalkane, a hydrofluoroalkane often having a numerical ratio F / H less than or equal to 1 is often used. Specific examples of hydrofluoroalkanes are chosen from difluoromethane (HFC- 32), 1,1-difluoroethane (HFC- 152a) and 1,1,1,3,3-pentafluorobutane (HFC- 365mfc). 1,1,1,3,3-pentafluorobutane is preferred.

 Alternatively, the blowing agent contains a non-flammable hydrofluoroalkane. Examples of such hydrofluoroalkanes are, inter alia, 1,1,1,2-tetrafluoroethane, 1,1,1,3,3-pentafluoropropane (HFC-245fa), 1,1,1,3,3, 3-hexafluoropropane (HFC-236fa) and 1,1,1,2,3,3,3heptafluoropropane (HFC-227ea). 1,1,1,3,3-Pentafluoropropane is preferred as the non-flammable blowing agent.

 As an alkyl ether, a dialkyl ether is often used comprising from 1 to 4 carbon atoms in each of the alkyl chains, such as dimethyl ether or diethyl ether.

 In a particular variant, the swelling agent contains a composition, preferably azeotropic or pseudo-azeotropic, of 1,1,1,3,3pentafluorobutane with at least one pentane or hexane, as described above.

Particular compositions of HFC-365mfc with these hydrocarbons which can be used in the process according to the invention are described in US Pat. No. 6,303,668 in the name of the Applicant.

 In a second particular variant, the flammable blowing agent contains a composition of 1,1,1,3,3-pentafluoropropane with at least one

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 pentane or hexane, as described above. The pentanes described above are preferred as pentane.

 In addition to the polyol, the swelling agent and the catalyst, it is possible to use in the process according to the invention various additives usually used for preparing polyurethane or modified polyurethane foams, such as in particular water, agents surfactants, antioxidants, flame retardants and / or pigments.

 In the method according to the invention, the use of a flame retardant is preferred. For example, flame retardants containing bromine or phosphorus can be used. Brominated flame retardants are chosen, for example, from brominated polyols such as in particular IXOL @ M125 brominated polyol or IXOL B251 brominated polyol sold by the Applicant.

 The use of a flame retardant agent containing phosphorus, optionally with a brominated flame retardant as described above is preferred. Specific examples of phosphorus-containing flame retardants are selected from triethyl phosphate (TEP), diethyl ethylphosphonate (DEEP), dimethyl methylphosphonate (DMMP), trichloropropyl phosphate (TCPP) and trichloroethyl phosphate (TCEP). Trichloropropyl phosphate (TCPP) is preferred.

 When using a phosphorus-containing flame retardant, the latter is generally used in an amount such that the phosphorus content in the foam is greater than or equal to 0.1% by weight. Often the quantity is such that this content is greater than or equal to 0.2% by weight. Preferably the quantity is such that this content is greater than or equal to 0.3% by weight. When using a flame retardant agent containing phosphorus, the latter is generally used in an amount such that the phosphorus content in the foam is less than or equal to 1% by weight. Often the amount is such that this content is less than or equal to 0.6% by weight. Preferably, the amount is such that this content is less than or equal to 0.5% by weight. By using the retarding agent in the specified amount, particularly good results have been obtained with the flammable blowing agents described above.

 The proportions of polyol, catalyst, swelling agent and optional additives in the process according to the invention vary, in particular according to the application, the type of foam prepared, the nature of the polyol and the nature of the

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 catalyst. In practice, the amount of catalyst or mixture of catalysts generally varies from about 0.05 to 10 parts by weight per 100 parts by weight of polyol. In general, the amount of blowing agent is from 1 to 80 parts by weight per 100 parts by weight of polyol. Preferably, it is from 10 to 60 parts by weight per 100 parts by weight of polyol. The amounts of water, surfactants or plasticizers are those conventionally used to prepare polyurethane or modified polyurethane foams.

 The foams obtained are often rigid foams. Preferably, the method according to the invention is applied for obtaining closed cell foams, generally having a closed cell content of at least 90%. These foams are particularly useful as thermal insulation materials. Obtaining polyisocyanurate foams is particularly preferred.

 Polyurethane foams, in particular polyisocyanurate foams can be produced according to various techniques which can be used on an industrial scale. We can cite in particular the implementation by projection, by injection into a mold kept under press, by effusion for the production of blocks according to a continuous or discontinuous process or by the technique of double conveyor with flexible or rigid facings.

 The invention also relates to the polyurethane foams which can be obtained by the process according to the invention.

 The invention also relates to a method of manufacturing a supported polyurethane or modified polyurethane foam according to which (a) a layer of polyepoxide according to the description above is deposited on at least part of a solid support; (b) a mixture of reagents suitable for implementing the process according to the invention is deposited at least on the polyepoxide layer; (c) reacting the mixture of reagents deposited according to the process according to the invention.

 Solid supports are chosen for example from metals, walls, for example concrete, glass and wood.

 The examples below illustrate the invention without limitation.

Example 1 - Manufacture of a polyepoxide from 2-butyne-1,4-diol
A condensation reaction of 1 mole of 2-butyne-1,4-diol was carried out with 3 moles of epichlorohydrin in the presence of a Lewis acid (BF3.etherate).

The chlorohydrin obtained was dissolved in a mixture

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 dichloromethane / methanol 2: 1 by weight. 2.2 moles of 10 N NaOH solution were added over 30 minutes. After complete introduction of the sodium hydroxide, the medium was maintained at 40 ° C. for 60 minutes with vigorous stirring. After cooling, the reaction mixture was extracted with water. The polyepoxide having 2 epoxy functionalities and a degree of epichlorohydrin condensation of 1.5 by hydroxy group was isolated by distillation.

Example 2 - Manufacture of a polyepoxide based on 2,3-dibromo-2butene-1,4-diol Mode A: The polyepoxide is accessed in a manner analogous to Example 1, by choosing 2,3-dibromo-2 -butene-1,4-diol obtained by bromination of 2-butyne-1,4-diol.

Mode B: The equivalent of bromine was added to the polyepoxide obtained in Example 1.

Example 3: Manufacture of a PIR foam
A polyol mixture was used comprising 97 g of polyester polyol STEPANPOL 2352.30 g of the polyepoxide obtained according to Example 1, 22 g of polyether polyol ARCOL 3758, 30 g of TCPP, 2.25 g of silicone surfactant, 0, 75 g of Dimethylcyclohexylamine (DMCHA), 4.5 g of DABCO TMR (diazabicyclooctane [2. 2.2]), 1.0 g of water and 32 g of n-pentane.

This mixture was then placed in the presence of 379 g of polymeric MDI (DESMODUR 44V20) to obtain a rigid polyisocyanurate foam.

The evaluation of the fire behavior of such foam according to the DIN 4102 test gives a B2 classification with a flame height of 12 cm.

Example 4: Manufacture of a PIR foam
A polyol mixture was used comprising 97 g of polyester polyol STEPANPOL 2352.30 g of the polyepoxide obtained according to example 2.22 g of polyether polyol ARCOL 3758, 30 g of TCPP, 2.25 g of silicone surfactant, 0, 75 g of Dimethylcyclohexylamine (DMCHA), 4.5 g of DABCO TMR (diazabicyclooctane [2. 2.2]), 1.0 g of water and 32 g of n-pentane.

This mixture was then placed in the presence of 379 g of polymeric MDI (DESMODUR 44V20) to obtain a rigid polyisocyanurate foam.

The evaluation of the fire behavior of such foam according to the DIN 4102 test gives a B2 classification with a flame height of 12 cm.

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Example 5 (comparison):
In this comparison example, the polyol mixture used included 127 g of polyester polyol STEPANPOL 2352.22 g of polyether polyol ARCOL 3758, 30 g of TCPP, 2.25 g of silicone surfactant, 0.75 g of Dimethylcyclohexylamine (DMCHA) , 4.5 g of DABCO TMR, 1.0 g of water and 32 g of n-pentane.

This mixture was then placed in the presence of 379 g of polymeric MDI (DESMODUR 44V20) to obtain a rigid polyisocyanurate foam.

The evaluation of the fire behavior of such foam according to the DIN 4102 test gives a B3 classification with a flame height of 16 cm.

Claims (20)

1 - Process for the manufacture of polyurethane or modified polyurethane foams in which at least one polyol is reacted with at least one isocyanate in the presence of a catalyst, a polyepoxide and a swelling agent other than a chlorofluorocarbon , in particular a blowing agent comprising an HFC and / or a flammable blowing agent.  2 - Process according to claim 1, in which the polyepoxide comprises from 2 to 6 epoxy functional groups.  3 - Process according to claim 1 or 2, wherein the polyepoxide comprises from 8 to 96 carbon atoms.  4 - Process according to any one of claims 1 to 3, in which the polyepoxide is capable of being obtained by a reaction of epichlorohydrin with an initiator compound containing at least 2 functional groups, each of the functional groups containing at least one atom active hydrogen.  5 - Process according to claim 4, wherein, the polyepoxide is capable of being obtained by the reaction of the initiator compound with 1 to 5 equivalents of epichlorohydrin by functional group of the initiator compound.  6 - Process according to claim 4 or 5, wherein the initiator compound is an alcohol chosen from 2-butyne-1,4-diol and 2,3-dibromo-2-butene-1,4diol.  7 - Process according to any one of claims 1 to 6, in which a flammable swelling agent is used.  8 - The method of claim 7, wherein the blowing agent contains a hydrocarbon.  9 - The method of claim 8 wherein the blowing agent contains a pentane.  10 - Process according to claim 9 wherein the pentane is npentane. <Desc / Clms Page number 12>  10 - The method of claim 7, wherein the blowing agent contains 1,1,1,3,3-pentafluorobutane.  11 - The method of claim 10, wherein the blowing agent contains a composition of 1,1,1,3,3-pentafluorobutane with at least one pentane or hexane.  12 - The method of claim 7, wherein the blowing agent is a composition of 1,1,1,3,3-pentafluoropropane with at least one pentane or hexane.  13 - Process according to any one of claims 1 to 12, wherein one implements an isocyanate of isocyanate index of at least 250 so as to obtain a polyisocyanurate foam.  14 - Process according to any one of claims 1 to 13, wherein the polyol is essentially free of phosphorus in its structure.  15 - Process according to any one of claims 1 to 14, in which a flame retardant agent containing phosphorus is used in an amount such that the content of phosphorus in the foam is 0.1 to 1% by weight .  16 - Polyurethane foam capable of being obtained by the process according to any one of claims 1 to 15.  17 - Foam according to claim 16, having a flame height of less than 15 cm when subjected to the test of standard EN ISO 11925-2 (foam B2).  18 - Foam according to claim 17, having a flame height of less than 13 cm when subjected to the test of standard EN ISO 11925-2 (foam B2).  19 - Polyepoxide according to claims 5 or 6.  20 - Method for manufacturing a supported polyurethane or modified polyurethane foam according to which <Desc / Clms Page number 13>  (a) a layer of polyepoxide is deposited on at least part of a solid support; (b) depositing a mixture of reagents suitable for carrying out the process according to any one of claims 1 to 15 at least on the polyepoxide layer; (c) reacting the mixture of reagents deposited according to the process according to any one of claims 1 to 15.