FR2810670A1 - Polyurethane foams for use as fire-resistant rigid foamed product are obtained from polyol compositions containing acetylene polyol, acting as reducer of viscosity of other polyols used - Google Patents

Abstract

Composition of polyols reactive with isocyanates, used in preparation of polyurethane or modified polyurethane foams, contains at least one acetylene polyol. Independent claims are also included for: (1) polyurethane or modified polyurethane foams incorporating at least one acetylene polyol and produced from polyol compositions; (2) process of production of polyurethane or modified polyurethane foams, in which at least one isocyanate is reacted with polyol composition; (3) pre-mixture comprising polyol composition and swelling agent; and (4) the use of acetylene polyol as reducer of viscosity of other polyols.

Description

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Polyurethane foams, compositions for use in their manufacture and process for the manufacture of foams
The present invention relates to polyurethane or modified polyurethane foams, compositions which can be used in their manufacture, as well as a process for the manufacture of these foams. It relates more particularly to rigid flame retardant foams and compositions which can be used in their production, based on halogenated polyols.

 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 130. By modified polyurethane is meant polymers resulting from the reaction of polyols and isocyanates which contain, in addition to urethane functions, 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 130 to 450. In the present description, polyurethane and modified polyurethane are generally designated by the term "PUR".

 It is well known that PUR foams can be prepared by reacting an isocyanate with an appropriate amount of a polyol or a mixture of polyols, in the presence of a blowing agent consisting of a volatile liquid, today hui typically 1,1-dichloro-1-fluoroethane, which is vaporized by the heat released by the reaction between the isocyanate and the polyol. In order to comply with environmental protection regulations, 1,1-dichloro-1-fluoroethane must ultimately be replaced by a blowing agent that is completely free of chlorine. Among these, hydrocarbons, such as n-pentane, isopentane and cyclopentane, appear to be usable blowing agents, although their use has a certain number of drawbacks, in particular the reduction in the fire resistance of PUR foams obtained.

 The object of the present invention is in particular to provide rigid flame retardant PUR foams which exhibit an improved level of flame retardancy and dimensional stability, even if they are produced by means of flammable blowing agents.

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 Another well known problem in the manufacture of PUR foams is linked to the high viscosity of certain polyols, which complicates their use.

Conventionally, this problem is resolved by marketing excessively viscous polyols in formulations where they are diluted by other ingredients involved in the manufacture of foam, for example, in the case of flame retardant foams, by means of phosphorus derivatives also acting as flame retardant. However, this reduces freedom when preparing formulations. In addition, compounds used as viscosity reducers, such as phosphorus derivatives, have the notorious drawback of having a plasticizing effect on PUR foams and, therefore, of reducing their mechanical properties and in particular their dimensional stability. The present invention also aims to provide polyol compositions with reduced viscosity which do not give rise to the above drawbacks.

 The invention therefore relates to polyol compositions reactive with isocyanates, which can be used in the preparation of polyurethane or modified polyurethane foams, comprising at least one acetylenic polyol, in particular a C4-C6 acetylenic diol, such as the but- 2-yne-1,4-diol (1,4butynediol), pent-2-yne-1,5-diol, pent-2-yne-1,4-diol, hex-2-yne-1 , 6-diol, hex-3-yne-1,5-diol and hex-3-yne-1,6-diol. 1,4-Butynediol is preferred. The compositions according to the invention also comprise one or more polyols conventionally used for preparing PUR foams. Mention may in particular be made of polyether polyols and polyester polyols. Polyols preferred in the compositions according to the invention are the halogenated polyols, usually used to improve the flame retardancy of the foams obtained. Acetylene polyols have in fact been found to be particularly effective in reducing the viscosity of halogenated polyols. The term “halogenated polyols” is intended to denote, for the purposes of the present invention, in particular polyether polyols and chlorinated, brominated or chlorobrominated polyester polyols. Mention may in particular be made, as halogenated polyether polyols, of polyether polyols consisting essentially of adducts of alkene oxides, at least part of which consists of halogenated alkene oxides, such as epichlorohydrin, epibromhydrin, the oxides of 3,3-dihalopropene and 3,3,3-trihalopropene on an initiating polyol monomer, optionally halogenated, such as for example ethylene glycol, glycerin, glycerol monohalohydrins, dibromoneopentyl glycol and 2 , 3-dibromo-1,4-butenediol. Halogenated polyether polyols of this type, essentially aliphatic in nature, marketed under the brand IXOL # are

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 described, for example, in Belgian patents 798,674 of April 25, 1973, 821,314 of October 22, 1974 and European patent 0 221,586 of October 20, 1986, all in the name of the Applicant and incorporated herein by reference. As halogenated polyesters-polyols, mention may be made in particular of brominated diesters of phthalic acid, such as those sold under the brands PHT4-diol # or SAYTEX # RB79.

 The weight proportion between the acetylene polyol and all of the other polyols in the compositions according to the invention is typically at least 1%. It is preferably at least 2%. In a particularly preferred manner, it is at least 5%. Generally, it does not exceed 30%. Most often, it does not exceed 20%. Advantageously, it does not exceed 15%.

 The invention also relates to PUR foams incorporating an acetylene polyol, in particular those obtained from the polyol compositions described above. Preferred are the flame retardant rigid PUR foams produced from the polyol compositions according to the invention containing a halogenated polyol. These foams have significantly improved fire resistance and dimensional stability.

 The invention also relates to a process for the production of PUR foams in which at least one isocyanate is reacted with a polyol composition as defined above. 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. As a rule, this reaction is carried out in the presence of a blowing agent, at least one catalyst and other usual additives.

 As blowing agent, mention may be made of hydro (chloro) fluoroalkanes, in particular 1,1-dichloro-1-fluoroethane (HCFC-141b), 1,1,1,3,3pentafluorobutane (HFC-365mfc) and 1 , 1,1,3,3-pentafluoropropane (HFC-245fa), as well as hydrocarbons, in particular cyclopentane, isopentane and n-pentane. These compounds can be used alone or in admixture or else in admixture with traditional blowing agents.

 The catalyst can comprise a compound catalyzing the formation of the urethane bond -NH - CO - O-, by reaction between a polyol and an isocyanate or activating the reaction between an isocyanate and water, such as tertiary amines and organic compounds d , tin, iron, mercury or lead. As tertiary amines, there may be mentioned in particular triethylamine, N, N-

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 dimethylcyclohexylamine (DMCHA), N-methylmorpholine (NMM), N-ethylmorpholine, dimethylethanolamine, diaza [2,2,2] bicyclooctane (triethylenediamine) and substituted benzylamines such as N, Ndimethylbenzylamine (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 for the manufacture of modified polyurethane foams (polyisocyanurates), comprise a compound catalyzing the trimerization of isocyanates into triisocyanurates. Compounds which catalyze the trimerization of isocyanates are in particular triazines and carboxylates of alkali metals and hydroxyalkylammonium carboxylates, for example potassium acetate.

 As usual additives, usually used to prepare polyurethane or modified polyurethane foams, mention may in particular be made of water, surfactants, antioxidants, flame retardants and / or pigments.

 As flame retardants, especially useful for the preparation of flame retardant foams, mention may be made of organic phosphorus compounds, generally phosphoric esters or phosphonates, optionally halogenated. The use of these phosphorus-containing additives which act in synergy with the halogenated polyols in terms of fireproofing is generally recommended to reach the highest levels of fireproofing, such as the Ml classification in the epiradiator test (according to the NF-P 92-501) or B2 classification according to DIN 4102. The use of an acetylene polyol in the manufacture of rigid PUR foams in the presence of phosphorus organic compounds is particularly advantageous, in that 'it makes it possible to neutralize the undesirable effects linked to the presence of phosphorus-containing additives on the mechanical properties of rigid PUR foams, without harming their flame-retardant properties. As nonlimiting examples of phosphorus organic compounds which can be used for the manufacture of rigid rigid PUR foams according to the invention, mention may be made of organic phosphates such as triethyl phosphates (TEP), tris (chloropropyl) ( TCPP) or phosphonates, such as for example dimethylphosphonate.

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

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 and the nature of the catalyst. They can be easily determined in each particular case. The amounts of water, surfactants, plasticizers and / or flame retardants are those conventionally used to prepare polyurethane or modified polyurethane foams.

 All other things remaining equal, the use of an acetylene polyol in the process for manufacturing PUR foams according to the invention results in an increase in the effectiveness of the swelling agent. Thus, it is possible to achieve a foam of a given density with less blowing agent.

 The rigid PUR foams according to the invention can be manufactured by any conventional foaming process, such as the one-step process, known as "one shot", the processes using a premix, a prepolymer or a semi-polymer, the pre-process -expansion says "frothing".

 A process to which preference is given is that using a premix in which a preformulated mixture (generally called "premix") is used, comprising as essential ingredients the polyol composition according to the invention and the swelling agent, the organic polyisocyanates being reacted with this premix only at the time of the manufacture of the PUR foam. The invention therefore also relates to premixes incorporating an acetylene polyol. In addition to the essential ingredients mentioned above, these premixes can contain other usual ingredients, namely catalysts, if necessary water, surfactants or stabilizers, pigments, fillers, etc. as described above and, moreover, well known to those skilled in the art.

 The premixes according to the invention containing. as essential ingredients at least one halogenated polyol, at least one acetylenic polyol, at least one swelling agent, as well as if appropriate a phosphorus organic compound, are very particularly suitable for the manufacture of rigid flame retardant PUR foams according to the invention by the premix process.

 The examples below illustrate the invention without limitation.

 The following examples are intended to illustrate the invention.

Example 1 20 g of 1,4-butynediol were added after grinding to 180 g of a chlorobrominated polyether polyol, sold by SOLVAY under the brand IXOL B350 and the main characteristics of which are: - hydroxyl number 353 mg KOH / g - equivalent weight 159

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- medium functionality 3 - chlorine content approx. 7.3% by weight - bromine content approx. 34.2% by weight
The viscosity of the mixture after complete dissolution of 1,4-butynediol, measured at 25 ° C., was 5620 cps, compared to 25000 cps for the polyether polyol IXOL # B350.

Example 2 20 g of 1,4-butynediol were added after grinding to 180 g of a brominated polyester polyol, sold by GREAT LAKES under the brand PHT4-DIOL #.

 The viscosity of the mixture after complete dissolution of 1,4-butynediol, measured at 25 ° C., was 7,420 cps, compared to 100,000 cps for the polyester polyol PHT4-DIOL #.

Example 3
A polyisocyanurate (PIR) foam of index 250 was prepared from several polyols including a polyol composition consisting of 90 parts by weight of chlorobrominated polyether polyol IXOL # M125 and 10 parts by weight of 1,4-butynediol , with a mixture of water and n-pentane as a blowing agent. The content of blowing agent used was 0.0746 mole per 100 g of foam. The foam obtained had a density of 33.2 kg / m3 and a flame height in the DIN 4102 (B2) test of 8.9 cm. An equivalent foam, not in accordance with the invention, prepared from polyether polyol IXOL # M125 without 1,4-butynediol and with a swelling agent content of 0.0838 mole per 100 g of foam, had a density. 36.5 kg / m3 and a flame height of 10.4 cm.

Example 4
A polyurethane foam of index 110 was prepared from several polyols, including a polyol composition consisting of 90 parts by weight of chlorobrominated polyether polyol IXOL B350 and 10 parts by weight of 1,4-butynediol, with a mixture water and n-pentane as the blowing agent. The foam obtained had a density of 28.7 kg / m3. An equivalent foam, not in accordance with the invention, prepared under the same conditions with the same chlorobrominated polyether-polyol diluted - in place of 1,4-butynediol - with a phosphorus derivative (mixture sold by SOLVAY under the brand IXOL # B251) had a density of 32 kg / m3.

Claims (10)

1. Composition of polyols reactive with isocyanates, usable in the preparation of polyurethane or modified polyurethane foams, comprising at least one acetylenic polyol.  2. Composition according to claim 1, in which the acetylene polyol is a C4-C6 acetylene diol, such as but-2-yne-1,4-diol (1,4-butynediol), pent-2-yne -l, 5-diol, pent-2-yne-l, 4-diol, hex-2-yne-l, 6diol, hex-3-yne-1,5-diol and hex- 3-yne-1,6-diol.  3. Composition according to claim 2, in which the acetylene polyol is but-2-yne-1,4-diol (1,4-butynediol).  4. Composition according to any one of claims 1 to 3, comprising a halogenated polyol.  5. Composition according to any one of claims 1 to 3, having a weight proportion between the acetylenic polyol and all of the other polyols from 1 to 30%.  6. Polyurethane or modified polyurethane foams incorporating an acetylene polyol.  7. Polyurethane or modified polyurethane foams according to claim 6, produced from the polyol compositions according to any one of claims 1 to 5.  8. A method of manufacturing polyurethane or modified polyurethane foams, in which at least one isocyanate is reacted with a polyol composition according to any one of claims 1 to 5.  9. Premix comprising a polyol composition according to any one of claims 1 to 5 and a swelling agent.  10. Use of an acetylene polyol as a viscosity reducer for polyols.