WO1994014882A1 - Mixtures useful for preparing a cellular polymeric material - Google Patents

Mixtures useful for preparing a cellular polymeric material Download PDF

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Publication number
WO1994014882A1
WO1994014882A1 PCT/EP1993/003633 EP9303633W WO9414882A1 WO 1994014882 A1 WO1994014882 A1 WO 1994014882A1 EP 9303633 W EP9303633 W EP 9303633W WO 9414882 A1 WO9414882 A1 WO 9414882A1
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WO
WIPO (PCT)
Prior art keywords
trifluoroethane
composition
physical
expansion
process according
Prior art date
Application number
PCT/EP1993/003633
Other languages
French (fr)
Inventor
James Franklin
Pierre Barthelemy
Noel Vanlautem
Annie Leroy
Original Assignee
Solvay (Societe Anonyme)
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority claimed from BE9201151A external-priority patent/BE1006443A3/en
Application filed by Solvay (Societe Anonyme) filed Critical Solvay (Societe Anonyme)
Priority to AU58148/94A priority Critical patent/AU5814894A/en
Publication of WO1994014882A1 publication Critical patent/WO1994014882A1/en

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Classifications

    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
    • C08J9/00—Working-up of macromolecular substances to porous or cellular articles or materials; After-treatment thereof
    • C08J9/04—Working-up of macromolecular substances to porous or cellular articles or materials; After-treatment thereof using blowing gases generated by a previously added blowing agent
    • C08J9/12—Working-up of macromolecular substances to porous or cellular articles or materials; After-treatment thereof using blowing gases generated by a previously added blowing agent by a physical blowing agent
    • C08J9/14—Working-up of macromolecular substances to porous or cellular articles or materials; After-treatment thereof using blowing gases generated by a previously added blowing agent by a physical blowing agent organic
    • C08J9/143—Halogen containing compounds
    • C08J9/144—Halogen containing compounds containing carbon, halogen and hydrogen only

Definitions

  • the present invention relates to a process for the preparation of cellular polymeric materials, in particular polyurethane foams, using a physical blowing agent with zero ozone-destroying potential (ODP), which can be carried out at moderate pressure. It also relates to premixes which can be used for the preparation of polyurethane foams.
  • ODP ozone-destroying potential
  • CFC-11 trichlorofluoromethane
  • CFC-12 dichlorodifluoromethane
  • HCFC-22 chlorodifluoromethane
  • CFC-113 trichlorotrifluoroethane
  • CFC-114 dichlorotetrafluoroethane
  • CFCs chlorofluoroalkanes
  • ODP ozone-destroying potential
  • HFC-134a 1,1,1,2-tetrafluoroethane
  • HFC-134a is used together with at least 50 X molar of carbon dioxide, generated by the reaction of water with the isocyanate.
  • swelling agents comprising hydrofluoroalkanes are used for the manufacture of polyurethane foams.
  • hydrofluoroalkanes mentioned 1,1,1,2-tetrafluoroethane is preferred each time.
  • 1,1,1,2-tetrafluoroethane When 1,1,1,2-tetrafluoroethane is used as a blowing agent, an immediate foaming phenomenon is frequently observed during the formation of the polymeric foam, known by the English term "frothing", linked to the too rapid vaporization of the blowing agent. This foaming phenomenon makes the manufacture of cellular materials more difficult and limits the possible appli ⁇ cations. Furthermore, the appearance of crevices in polyurethane foams manufactured using 1,1,1,2-tetrafluoroethane as a blowing agent is frequently observed. Another disadvantage of using 1,1,1,2-tetrafluoroethane as a blowing agent is linked to the formation of a possibly large proportion of open cells in cellular materials. These various drawbacks are at the origin of an increase in the thermal conductivity of the cellular materials obtained with 1,1,1,2-tetrafluoroethane and a fall in their mechanical resistance.
  • the present invention relates to a process for the preparation of cellular polymeric materials using a physical bulking agent whose impact on the ozone layer is zero and which does not have the above-mentioned drawbacks.
  • the present invention relates to a process for preparing a cellular polymeric material according to which a composition to be expanded is treated in the presence of a physical expansion composition, which is characterized in that the expansion composition comprises 1.1, 2-trifluoroethane (HFC-143).
  • the term “physical expansion composition” is intended to denote a volatile compound or a mixture of volatile compounds which are substantially chemically inert with respect to polymeric materials or their precursor monomers and which, by passing to the gaseous state, are capable of causing a volume expansion of said materials. Subsequently, such a volatile compound is called a physical blowing agent.
  • 1,1,1,2-tetrafluoroethane which do not allow, when used as the sole physical blowing agents, to obtain satisfactory cellular polymeric materials
  • 1,1,2-trifluoroethane is an excellent physical blowing agent for the production of cellular polymeric materials, in particular for those based on polyurethane or polystyrene, very particularly for those based on polyurethane.
  • the quality of the cellular polymeric materials produced using this physical blowing agent is substantially identical to that of the products obtained conventionally, for example using CFC-11.
  • the physical expansion composition can consist only of 1,1,2-trifluoroethane. Preferably, it also comprises one or more other physical blowing agents.
  • the physical expansion composition however always comprises at least 10 X molar of 1,1,2-trifluoroethane, preferably at least 20 X molar of 1,1,2-trifluoroethane. Particularly preferably, it contains at least 40 X molar.
  • the other swelling agent is most often a hydrochlorofluoroalkane preferably chosen from 1,1-dichloro-l-fluoroethane, l-chloro-l, l-difluoroethane and chlorodifluoromethane or a hydrofluoroalkane other than 1,1,2-trifluoroethane, corresponding to the general formula C x F z H (2 ⁇ + 2-z) in which x represents an integer from 1 to 4 and z an integer from x to 2x + l .
  • Mixtures of these other blowing agents can also be used.
  • these other swelling agents those which are non-flammable are preferred.
  • An advantageous physical expansion composition in the process according to the invention comprises a mixture of 1,1,2-trifluoroethane and chlorodifluoromethane.
  • the chlorodifluoromethane / 1,1,2-trifluoroethane molar ratio is generally greater than 0.1. It is preferably greater than 0.3. Particularly preferably, it is greater than 0.5.
  • This chlorodifluoromethane / 1,1,2-trifluoroethane molar ratio is generally less than 5. It is preferably less than 3.
  • the molar ratios of 0.8 to 2 are very particularly preferred.
  • hydrofluoroalkanes are particularly preferred.
  • Hydrofluoroalkanes corresponding to the general formula C x F z H (2 ⁇ + 2-z) - u i can advantageously be used as physical blowing agents other than 1,1,2-trifluoroethane in the process according to the invention are in particular difluoromethane, 1,1-difluoroethane, 1,1,1-trifluoroethane, 1,1,1,2-tetrafluoroethane, pentafluoroethane, 1,1,1,2,3,3,3 -heptafluoropropane, 1,1,1,3,3- pentafluorobutane or 1,1,1,4,4,4-hexafluorobutane.
  • a physical expansion composition very particularly preferred in the process according to the invention comprises a mixture of 1,1,2-trifluoroethane and 1,1,1,2-tetrafluoroethane.
  • the 1,1,1,2-tetrafluoroethane / 1,1,2-trifluoroethane molar ratio is generally greater than 0.1. It is preferably greater than 0.3. In a particularly preferred manner, it is greater than 0.5. Very particularly preferably, it is greater than 0.7.
  • This 1,1,1,2-tetrafluoroethane / 1,1,2-trifluoroethane molar ratio is generally less than 8. It is preferably less than 5.
  • the physical expansion composition comprises a swelling agent other than the non-flammable 1,1,2-trifluoroethane
  • the proportion between 1,1,2-trifluoroethane and this swelling agent is preferably adjusted in such a way that the composition expansion is non-flammable.
  • the composition is non-flammable when the molar ratio 1.1, 1,2-tetrafluoroethane / 1,1,2-trifluoroethane is greater than 0.55.
  • the cellular polymeric materials are obtained by bringing the expansion composition into intimate contact with a composition to be expanded.
  • the composition to be expanded contains either reactive monomers, forming the polymeric material by polymerization, or the polymer already synthesized.
  • the composition to be expanded may contain various additives, such as surfactants, stabilizers, etc.
  • the composition to be expanded contains the reactive monomers, it generally also contains other additives useful for polymerization.
  • a chemical swelling agent consisting of a gaseous compound chemically generated in situ, in the composition to be expanded, by the reaction of precursors of this gaseous compound with certain precursor constituents polymeric material.
  • Carbon dioxide generated by the reaction of water with an excess of isocyanate, is a preferred chemical blowing agent.
  • the method according to the invention makes it possible to obtain cellular polymeric materials of very good quality by means of physical blowing agents having a zero ODP, without having to jointly use a chemical blowing agent in the majority proportion.
  • the proportion of chemical blowing agent in the composition of the gas occupying the cells of the cellular polymeric materials obtained by the process according to the invention can vary within wide limits.
  • the molar proportion of these chemical blowing agents in the composition of the gas occupying the foam cells is most often greater than 5 mol%, preferably, greater than 10 X molar.
  • the physical expansion composition is used in the process according to the invention in an amount adapted to the density of the cellular polymeric material that it is desired to obtain. It is possible to prepare, using the process according to the invention, cellular polymeric materials with a density varying between 10 and 200 kg / ⁇ .3, preferably between 15 and 100 kg / m ⁇ , particularly preferably between 20 and 80 kg / m ⁇ .
  • the quantity of the physical expansion composition to be used in the process according to the invention also varies according to the nature of the polymeric material, according to the technique used for shaping the material, according to whether the desired foam is a rigid foam. or flexible, etc. Generally, the amount of the physical expansion composition to be used can be easily determined by those skilled in the art.
  • the composition of physical expansion is advantageously present in an amount of 0.5 to 20% of the total weight of the composition to be expanded and of the composition of physical expansion.
  • the physical expansion composition is present in an amount of 1 to 18% of the total weight of the composition to be expanded and of the physical expansion composition. Particularly preferably, it is present in an amount of 1.5 to 15% of the total weight of the composition to be expanded and of the physical expansion composition. Most preferably, it is present in an amount of 2 to 12% of the total weight of the composition to be expanded and of the physical expansion composition.
  • the use of physical expansion compositions according to the invention is possible in the various processes for the preparation of cellular polymeric materials, in particular in the known processes for the preparation of polymeric foams in which the monomeric reagents are first mixed with the physical expansion composition, optionally kept in the form of premixes, then subsequently polymerized, the exothermic nature of the reaction causing the vaporization of the physical expansion composition, which causes the expansion of the polymeric material.
  • the use of the physical expansion compositions according to the invention is also possible in other known expansion methods, consisting in the injection under pressure of the physical expansion composition in the liquid state into the polymeric material, followed by decompression which causes the passage of the physical expansion composition in gaseous form and, therefore, the expansion of the polymeric material.
  • cellular polymeric materials which can be produced by the process according to the invention, mention may be made of the following materials: polyurethanes, poly ⁇ amides, polysulfones, polyolefins, such as polyethylene and polypropylene, polystyrene, polycarbonate, polyethylene terephthalate, polyvinyl chloride, phenolic resins, and the copolymers of these various materials.
  • polyurethanes poly ⁇ amides, polysulfones, polyolefins, such as polyethylene and polypropylene
  • polystyrene polycarbonate
  • polyethylene terephthalate polyvinyl chloride
  • phenolic resins phenolic resins
  • 1,1,2-trifluoroethane has a satisfactory solubility in polystyrene.
  • Cellular polystyrene materials can be prepared using conventional extrusion methods.
  • a physical expansion composition comprising 1,1,2-trifluoroethane is injected under pressure into a flow of plasticized poly ⁇ styrene by heating, inside an extruder, the decompression obtained at the outlet of the extruder causing the physical blowing agent to pass in gaseous form and, therefore, the expansion of the polystyrene by blowing.
  • the physical expansion compositions comprising 1,1,2-trifluoroethane and chlorodifluoromethane appear particularly advantageous for the production of polystyrene foams. It has in fact been observed that the presence of chloro ⁇ difluoromethane causes a significant increase in the solubility of 1,1,2-trifluoroethane in polystyrene.
  • the physical expansion composition is typically used at a rate of 5 to 20% by weight of the polymer.
  • polyurethane is intended to denote, for the purposes of the present invention, all the polymers resulting from the reaction of polyols and isocyanates comprising urethane functions:
  • polyurethane includes polymers resulting from the reaction of polyols and isocyanates which contain, in addition to urethane functions, other types of function, such as for example isocyanuric functions 0
  • modified polyurethane or "polyisocyanurate”. It is well known that obtaining poly ⁇ urethane or "modified” polyurethane essentially depends on the excess of isocyanate used, as well as on the type of catalyst used.
  • the polyurethane foams as defined above are obtained by reaction and expansion of polyols and isocyanates in the presence of the usual ingredients well known to those skilled in the art and of the physical expansion composition .
  • a wide range of polyols already disclosed in the prior art can be used, including in particular polyether polyols and polyester polyols.
  • isocyanates already disclosed in the prior art can be used in the process of the invention.
  • Isocyanates conventionally used are, for example, aliphatic isocyanates, such as hexamethylene diisocyanate and aromatic isocyanates, such as tolylene diisocyanate or diphenylmethane diisocyanate (MDI).
  • the polymerization reaction requires the presence of a catalyst.
  • Any catalyst usually used in the previous processes for the preparation of polyurethane foams is suitable for the process according to the invention.
  • the amount of catalyst used varies from about 0.05 X to about 2 X by weight relative to the amount of polyol used.
  • additives can be incorporated into the composition to be expanded, in particular water, stabilizers, surfactants such as silicone oils, crosslinking agents, such as glycerin, plasticizers, antioxidants and flame retardants.
  • the amount of water used is adapted to the proportion of carbon dioxide desired in the composition of the gas occupying the cells of the foams obtained by the process according to the invention.
  • polyurethane foams these are prepared by reaction of the monomers (polyols and isocyanates) contained in the composition to be expanded, with the various additives, in the required proportions, in the presence of the composition of physical expansion.
  • the various additives in the required proportions, in the presence of the composition of physical expansion.
  • premixes in which the physical expansion composition and various additives are combined with one of the reactive monomers, most often with the polyol, optionally kept in this form for a certain time, then mixed. with the other reactive monomer just before the preparation of the foam.
  • the polymerization, expansion and hardening reactions and the conditions under which these reactions are carried out are well known in the prior art and are hardly affected by the use of 1,1,2-trifluoroethane as agent bulging physical.
  • the invention also relates to premixes which can be used for the preparation of polyurethane foams, comprising at least one polyol and one physical expansion composition, which are characterized in that the physical expansion composition comprises 1,1,2-trifluoroethane .
  • Premixes according to the invention may optionally include other swelling agents, as defined above.
  • the polyols included in the premixes according to the invention are typically the polyols conventionally used in the preparation of polyurethane foams, such as polyether polyols and polyester polyols.
  • the premixes according to the invention can also comprise various additives chosen from polymerization catalysts, stabilizers, surfactants such as silicone oils, crosslinking agents such as glycerin, plasticizers, antioxidants and flame retardants.
  • the physical expansion composition generally constitutes from 1 to 30%, preferably from 2 to 25%, of the weight of the premix.
  • the premixes according to the invention have, at the same overall molar amount of the physical expansion composition, a vapor pressure very much lower than that of premixes containing 1,1,1,2-tetrafluoroethane as the sole physical blowing agent. Their handling and storage are greatly facilitated.
  • Example 1 a rigid polyurethane foam was prepared from a composition comprising a polymeric diphenylmethane diisocyanate DESMODUR- y 44V20 marketed by BAYER, an amino polyol ARCOI® 3770 marketed by ARCO, a silicone surfactant TEGOSTAB-VB 1048 marketed by Th. GOLDSCHMIDT, N-methylmorpholine (NMM), water and an expansion composition consisting exclusively of 1,1,2-trifluoroethane. Diphenylmethane diisocyanate (MDI) and polyol were introduced in ratios such that the index was 110.
  • MDI diphenylmethane diisocyanate
  • MDI diphenylmethane diisocyanate
  • polyol were introduced in ratios such that the index was 110.
  • Example 2 the physical expansion composition consists of 1,1,2-trifluoroethane and 1,1,1,2-tetrafluoroethane.
  • the expansion composition consisted of 100 X of 1,1,1,2-tetrafluoroethane and, in Example 4 (C), in 100 X of trichlorofluoromethane (CFC-11).
  • the foams were prepared by progressive addition of the physical expansion composition previously liquefied by cooling, to the mixture of all the ingredients except for MDI, previously cooled to -28 ° C.
  • 1,1,2-trifluoroethane was first added, and then 1,1,1,2-tetrafluoroethane.
  • Example 3 (C) 1,1,1,2-tetrafluoroethane was added in large excess, so as to reach the limit of solubility of 1,1,1,2-tetrafluoroethane in polyol.
  • the temperature of the premix was, in each case, about - 7 ° C.
  • the amount of physical blowing agent dissolved in the premix was measured by weighing.
  • the MDI previously cooled to about 3 ° C, was then added to the premix.
  • the composition obtained was thoroughly mixed for 25 seconds using a multi-blade type agitator rotating at 1600 revolutions per minute, then transferred to a free expansion mold.
  • the amount of physical blowing agents found in the foams was measured as follows. Small samples of mosses were introduced into a pill bottle hermetically sealed by a rubber septum, in which they are ground. The gas phase is then analyzed by gas chromatography. Due to surface effects, the results obtained by this method generally represent a value lower than the quantity actually present in the foam. Relative conclusions may nevertheless be drawn from it.
  • Example 3 shows the advantage linked to the use of a composition comprising 1,1,2-trifluoroethane as regards the lightness of the foam produced.
  • a comparison of the results of Examples 2 and 3 (C) shows that, when the physical blowing agent comprises a mixture of 1,1,2-trifluoroethane and 1,1,1,2-tetrafluoroethane, the amount of 1.1 , 1,2-tetrafluoroethane dissolved in the premix, at identical temperature and pressure, is more important than in the absence of 1,1,2-trifluoroethane. Likewise, the quantity of 1,1,1,2-tetrafluoroethane incorporated into the foam is greater in the presence of 1,1,2-trifluoroethane.
  • Rigid polyurethane foams were prepared using an ADMIRAL M8-2H low pressure machine allowing direct injection of the physical expansion composition into the mixing head.
  • the physical expansion composition taken in the liquid phase was introduced into the mixing head at a controlled flow rate under a pressure of 20 bar.
  • the machine was equipped either with a conventional mechanical mixer (denoted M in table II), or with a helical static mixer (denoted S in table II).
  • the foams were prepared from a composition comprising a polymeric diphenylmethane diisocyanate (MDI) DESM0DUR 44V20 marketed by BAYER, an amino polyol based on sucrose CARAD0I.B) 585-8 marketed by SHELL, trichloropropylphosphate (TCPP) , a KACESTA ⁇ L silicone surfactant sold by S0LVAY FLUOR UND DERIVATE, a mixture of catalysts consisting of catalyst DABC0_- ) 33LV sold by AIR PRODUCTS and dimethylethanolamine, water and an expansion composition in the weight proportions detailed in Table II.
  • MDI and the polyol were introduced in reports such that the index was 110. For each foam, the density, the percentage of closed cells and the quantity of blowing agent found were measured. These different characteristics are collated in Table II.
  • the percentage of closed cells was determined according to standard ASTM D1940.
  • the amount of blowing agent found in the foam was determined according to the same procedure as that used for Examples 1 to 4. This amount is expressed as a percentage of the theoretical amount used in the formulation.
  • the ADMIRAL M8-2H low-pressure machine used to carry out the tests of Examples 5 to 10 was equipped with a station for premixing the physical expansion composition with the polyol and with a tank for storing the premix under pressure. of 2 bar.
  • Two rigid polyurethane foams were prepared by introducing into the mixing head of the machine equipped with a mechanical mixer, a polymeric diphenylmethane isocyanate (MDI) and a premix containing a physical expansion composition, an amino polyol based on sucrose, a brominated polyether polyol IXOL B 251, a hydroxylated crosslinking agent, as well as a small amount of silicone surfactant, flame retardant phosphorous additive and amino catalyst. MDI and polyols are introduced in reports such that index 110 is reached.
  • MDI polymeric diphenylmethane isocyanate
  • 1,1-Dichloro-1-fluoroethane was used as composition for physical expansion in Example 11 (C) and 1,1,2-trifluoroethane in Example 12.
  • Example 12 demonstrate that it is possible to prepare rigid polyurethane foams having satisfactory properties by means of a low-pressure machine, according to the conventional procedure using the physical expansion composition and the (s ) polyol (s) in the form of a premix. These results further confirm that a large proportion of the 1,1,2-trifluoroethane used as a blowing agent actually remains in the foam, a proportion greater than that of 1,1-dichloro-l-fluoroethane when the latter is used as a blowing agent under identical conditions. Examples 13 to 22
  • the advantage of the process according to the invention for preparing polystyrene foams has been estimated by measuring the solubility of different expansion compositions in polystyrene.
  • a nacelle consisting of a stainless steel screen and containing VESTYROt® polystyrene granules type 114 from HULS AG, covered with a 0.5 l capacity, was introduced into a stainless steel reactor with a capacity of 0.5 l. glass marbles.
  • the reactor was placed under vacuum and cooled to -70 ° C. then a physical expansion composition consisting of one or two hydro- (chloro) fluoroalkanes was introduced into the reactor in one sufficient to immerse all the polystyrene granules. After 2 and a half days at constant temperature, the content of hydro (chloro) fluoroalkane (s) in the polystyrene granules was determined.
  • Table IV The results obtained for different expansion compositions are presented in Table IV.
  • Chlorodifluoromethane and l-chloro-l, l-difluoroethane, conventional swelling agents of polystyrene have very good solubility in polystyrene (Examples 13 (C) to 16 (C)).
  • these compounds contain chlorine and their use will be increasingly regulated in the future.
  • 1,1,2-trifluoro ⁇ ethane has a significantly lower solubility at room temperature than these conventional compounds (Example 17) but it has been observed that the solubility of 1,1,2-trifluoroethane increases much more rapidly with temperature than the solubility of chlorodifluoromethane or l-chloro-l, l-difluoroethane.
  • Examples 21 and 22 (C) demonstrates the particularly advantageous behavior of the expansion compositions according to the invention containing 1,1,2-trifluoroethane and chlorodifluoromethane. While the presence of 1,1,1,2-tetrafluoroethane in the expansion composition causes a significant reduction in the solubility of chlorodifluoromethane in polystyrene (example 22 (C)), the simultaneous presence of 1, 1,2-trifluoroethane and chlorodifluoromethane in the expansion composition causes a large increase in the solubility of 1,1,2-trifluoroethane, without affecting the solubility of chloro-difluoromethane (Example 21). TABLE I

Abstract

1,1,2-trifluoroethane used as a physical blowing agent for prepa ring cellular polymeric materials, in particular polystyrene or polyurethane foams.

Description

MELANGES UTILISABLE POUR LE PREPARATION D UN MATERIAU POLYMERIQUE CELLULAIRE. MIXTURES FOR USE IN THE PREPARATION OF A CELLULAR POLYMERIC MATERIAL.
La présente invention concerne un procédé de préparation de matériaux polymériques cellulaires, notamment de mousses de poly¬ urethane, mettant en oeuvre un agent gonflant physique au poten¬ tiel destructeur de l'ozone (ODP) nul, réalisable à pression modérée. Elle concerne aussi des prémélanges utilisables pour la préparation de mousses de polyurethane.The present invention relates to a process for the preparation of cellular polymeric materials, in particular polyurethane foams, using a physical blowing agent with zero ozone-destroying potential (ODP), which can be carried out at moderate pressure. It also relates to premixes which can be used for the preparation of polyurethane foams.
Dans les procédés de préparation de matériaux polymériques cellulaires, tels que des mousses de polyurethane, le trichloro- fluorométhane (CFC-11), le dichlorodifluorométhane (CFC-12) et dans une moindre mesure, le chlorodifluorométhane (HCFC-22), le trichlorotrifluoroéthane (CFC-113) et le dichlorotétrafluoro- éthane (CFC-114) ont été pendant longtemps utilisés comme agents gonflants. En raison de sa très faible conductibilité thermique, le CFC-11 permet d'obtenir des mousses de polyurethane rigides particulièrement isolantes, lesquelles sont utilisées intensi¬ vement comme isolants thermiques, notamment dans les domaines du bâtiment, de la réfrigération et des transports.In processes for the preparation of cellular polymeric materials, such as polyurethane foams, trichlorofluoromethane (CFC-11), dichlorodifluoromethane (CFC-12) and, to a lesser extent, chlorodifluoromethane (HCFC-22), trichlorotrifluoroethane (CFC-113) and dichlorotetrafluoroethane (CFC-114) have long been used as blowing agents. Because of its very low thermal conductivity, CFC-11 makes it possible to obtain particularly insulating rigid polyurethane foams, which are used intensively as thermal insulators, in particular in the fields of building, refrigeration and transport.
Toutefois, les chlorofluoroalcanes complètement halogènes (CFC) traditionnellement utilisés comme agents gonflants sont aujourd'hui suspectés de provoquer la destruction de la couche d'ozone stratosphérique. L'influence qu'un produit peut avoir sur la couche d'ozone est quantifiée par son potentiel destruc¬ teur de l'ozone (ODP) et est exprimée relativement à l'ODP du CFC-11. Les hydrofluoroalcanes exempts de chlore ou de brome sont inertes vis-à-vis de la couche d'ozone et ont dès lors été proposés comme agents gonflants dans la fabrication de matériaux polymériques cellulaires. C'est ainsi que dans la demande de brevet WO 91/12289, on propose de préparer une mousse de poly- uréthane rigide à cellules fermées en présence d'un agent gonflant physique comprenant un polyfluorocarbure en C2~Cg qui ne contient pas d'atomes de chlore ni de brome. Dans cette demande de brevet, le 1,1,1,2-tétrafluoroéthane (HFC-134a) est préféré. Dans les exemples, le HFC-134a est mis en oeuvre conjointement avec au moins 50 X molaire de dioxyde de carbone, généré par la réaction d'eau avec l'isocyanate.However, fully halogenated chlorofluoroalkanes (CFCs) traditionally used as blowing agents are today suspected of causing the destruction of the stratospheric ozone layer. The influence that a product can have on the ozone layer is quantified by its ozone-destroying potential (ODP) and is expressed relative to the ODP of CFC-11. Hydrofluoroalkanes free from chlorine or bromine are inert towards the ozone layer and have therefore been proposed as blowing agents in the manufacture of cellular polymeric materials. Thus, in patent application WO 91/12289, it is proposed to prepare a rigid polyurethane foam with closed cells in the presence of an agent. physical bulking agent comprising a C2 ~ Cg polyfluorocarbon which does not contain chlorine or bromine atoms. In this patent application, 1,1,1,2-tetrafluoroethane (HFC-134a) is preferred. In the examples, HFC-134a is used together with at least 50 X molar of carbon dioxide, generated by the reaction of water with the isocyanate.
Dans le brevet US-4945119 et dans la demande de brevet EP-477920, on utilise, pour la fabrication de mousses de poly¬ urethane, des agents gonflants comprenant des hydrofluoroalcanes. Parmi les hydrofluoroalcanes cités, le 1,1,1,2-tétrafluoroéthane est chaque fois préféré.In US Pat. No. 4,945,119 and in Patent Application EP-477,920, swelling agents comprising hydrofluoroalkanes are used for the manufacture of polyurethane foams. Among the hydrofluoroalkanes mentioned, 1,1,1,2-tetrafluoroethane is preferred each time.
Le 1,1,1,2-tétrafluoroéthane présente cependant certains inconvénients. Il est gazeux dans les conditions normales de température et de pression (point d'ébullition à pression atmos- phérique = - 26,5 °C). Sa solubilité dans les polyols ou dans les isocyanates mis en oeuvre pour la préparation des mousses de polyurethane, ainsi que dans le polystyrène, est très faible. A pression atmosphérique et température ambiante, la quantité de HFC-134a dissoute dans un polyol classique est de l'ordre d'à peine 2 à 5 % en poids, quantité insuffisante pour obtenir des matériaux polymériques cellulaires de densité adéquate. Certes, à pression plus élevée, des quantités plus importantes peuvent être dissoutes dans le polyol. Cela impose toutefois de recourir à un équipement approprié et coûteux, comportant généralement des installations de stockage et de mélange pressurisées. Lorsque le 1,1,1,2-tétrafluoroéthane est utilisé comme agent gonflant, on observe fréquemment un phénomène de moussage immédiat lors de la formation de la mousse polymérique, connu sous le vocable anglo- saxon "frothing", lié à la trop rapide vaporisation de l'agent gonflant. Ce phénomène de moussage rend la fabrication des matériaux cellulaires plus difficile et en limite les appli¬ cations possibles. On observe par ailleurs fréquemment l'appa¬ rition de crevasses dans les mousses de polyurethane fabriquées en utilisant du 1,1,1,2-tétrafluoroéthane comme agent gonflant. Un autre inconvénient de l'utilisation du 1,1,1,2-tétrafluoro- éthane comme agent gonflant est lié à la formation d'une proportion pouvant être importante de cellules ouvertes dans les matériaux cellulaires. Ces différents inconvénients sont à l'origine d'une augmentation de la conductibilité thermique des matériaux cellulaires obtenus avec le 1,1,1,2-tétrafluoroéthane et d'une chute de leur résistance mécanique.1,1,1,2-tetrafluoroethane has certain disadvantages, however. It is gaseous under normal temperature and pressure conditions (boiling point at atmospheric pressure = - 26.5 ° C). Its solubility in polyols or in isocyanates used for the preparation of polyurethane foams, as well as in polystyrene, is very low. At atmospheric pressure and ambient temperature, the amount of HFC-134a dissolved in a conventional polyol is of the order of barely 2 to 5% by weight, an amount insufficient to obtain cellular polymeric materials of adequate density. Certainly, at higher pressure, larger amounts can be dissolved in the polyol. However, this requires the use of appropriate and expensive equipment, generally comprising pressurized storage and mixing facilities. When 1,1,1,2-tetrafluoroethane is used as a blowing agent, an immediate foaming phenomenon is frequently observed during the formation of the polymeric foam, known by the English term "frothing", linked to the too rapid vaporization of the blowing agent. This foaming phenomenon makes the manufacture of cellular materials more difficult and limits the possible appli¬ cations. Furthermore, the appearance of crevices in polyurethane foams manufactured using 1,1,1,2-tetrafluoroethane as a blowing agent is frequently observed. Another disadvantage of using 1,1,1,2-tetrafluoroethane as a blowing agent is linked to the formation of a possibly large proportion of open cells in cellular materials. These various drawbacks are at the origin of an increase in the thermal conductivity of the cellular materials obtained with 1,1,1,2-tetrafluoroethane and a fall in their mechanical resistance.
La présente invention a pour objet un procédé de préparation de matériaux polymériques cellulaires mettant en oeuvre un agent gonflant physique dont l'impact sur la couche d'ozone est nul et qui ne présente pas les inconvénients sus-mentionnés. La présente invention concerne un procédé de préparation d'un matériau polymérique cellulaire selon lequel on traite une composition à expanser en présence d'une composition d'expansion physique, qui se caractérise en ce que la composition d'expansion comprend du 1,1,2-trifluoroéthane (HFC-143). Par composition d'expansion physique, on entend désigner un composé volatil ou un mélange de composés volatils qui sont sensiblement inertes chimiquement vis-à-vis des matériaux poly¬ mériques ou de leurs monomères précurseurs et qui, par passage à l'état gazeux, sont capables de provoquer une expansion volumique desdits matériaux. Par la suite, un tel composé volatil est appelé agent gonflant physique.The present invention relates to a process for the preparation of cellular polymeric materials using a physical bulking agent whose impact on the ozone layer is zero and which does not have the above-mentioned drawbacks. The present invention relates to a process for preparing a cellular polymeric material according to which a composition to be expanded is treated in the presence of a physical expansion composition, which is characterized in that the expansion composition comprises 1.1, 2-trifluoroethane (HFC-143). The term “physical expansion composition” is intended to denote a volatile compound or a mixture of volatile compounds which are substantially chemically inert with respect to polymeric materials or their precursor monomers and which, by passing to the gaseous state, are capable of causing a volume expansion of said materials. Subsequently, such a volatile compound is called a physical blowing agent.
Contrairement aux autres fluoroéthanes, tels le 1,1,1,2-tétrafluoroéthane, qui ne permettent pas, lorsqu'ils sont utilisés comme seuls agents gonflants physiques, d'obtenir des matériaux polymériques cellulaires satisfaisants, il a été trouvé, de manière surprenante, que le 1,1,2-trifluoroéthane est un excellent agent gonflant physique pour la production de matériaux polymériques cellulaires, en particulier pour ceux à base de polyurethane ou de polystyrène, tout particulièrement pour ceux à base de polyurethane. La qualité des matériaux poly¬ mériques cellulaires produits en utilisant cet agent gonflant physique est sensiblement identique à celle des produits obtenus conventionnellement, par exemple à l'aide de CFC-11.Unlike other fluoroethanes, such as 1,1,1,2-tetrafluoroethane, which do not allow, when used as the sole physical blowing agents, to obtain satisfactory cellular polymeric materials, it has been found, surprisingly , that 1,1,2-trifluoroethane is an excellent physical blowing agent for the production of cellular polymeric materials, in particular for those based on polyurethane or polystyrene, very particularly for those based on polyurethane. The quality of the cellular polymeric materials produced using this physical blowing agent is substantially identical to that of the products obtained conventionally, for example using CFC-11.
En raison de l'absence de chlore dans sa structure molécu- laire, le 1,1,2-trifluoroéthane présente l'avantage de posséder un ODP nul. Dans le procédé selon l'invention, la composition d'expansion physique peut être constituée uniquement de 1,1,2-trifluoroéthane. De préférence, elle comprend en outre un ou plusieurs autres agents gonflants physiques. La composition d'expansion physique comprend cependant toujours au moins 10 X molaire de 1,1,2-trifluoroéthane, de préférence au moins 20 X molaire de 1,1,2-trifluoroéthane. De manière particulièrement préférée, elle en contient au moins 40 X molaire.Due to the absence of chlorine in its molecular structure, 1,1,2-trifluoroethane has the advantage of having a zero ODP. In the process according to the invention, the physical expansion composition can consist only of 1,1,2-trifluoroethane. Preferably, it also comprises one or more other physical blowing agents. The physical expansion composition however always comprises at least 10 X molar of 1,1,2-trifluoroethane, preferably at least 20 X molar of 1,1,2-trifluoroethane. Particularly preferably, it contains at least 40 X molar.
L'autre agent gonflant est le plus souvent un hydrochloro- fluoroalcane choisi de préférence parmi le 1,1-dichloro-l-fluoro- éthane, le l-chloro-l,l-difluoroéthane et le chlorodifluoro- méthane ou un hydrofluoroalcane autre que le 1,1,2-trifluoro- éthane, répondant à la formule générale CxFzH(2χ+2-z) dans laquelle x représente un nombre entier de 1 à 4 et z un nombre entier de x à 2x+l. Des mélanges de ces autres agents gonflants peuvent également être utilisés. Parmi ces autres agents gonflants, ceux étant ininflammables sont préférés.The other swelling agent is most often a hydrochlorofluoroalkane preferably chosen from 1,1-dichloro-l-fluoroethane, l-chloro-l, l-difluoroethane and chlorodifluoromethane or a hydrofluoroalkane other than 1,1,2-trifluoroethane, corresponding to the general formula C x F z H (2χ + 2-z) in which x represents an integer from 1 to 4 and z an integer from x to 2x + l . Mixtures of these other blowing agents can also be used. Among these other swelling agents, those which are non-flammable are preferred.
Une composition d'expansion physique avantageuse dans le procédé selon l'invention comprend un mélange de 1,1,2-trifluoro- éthane et de chlorodifluorométhane. Dans cette composition d'expansion physique avantageuse, le rapport molaire chlorodi¬ fluorométhane / 1,1,2-trifluoroéthane est généralement supérieur à 0,1. Il est de préférence supérieur à 0,3. De manière parti¬ culièrement préférée, il est supérieur à 0,5. Ce rapport molaire chlorodifluorométhane / 1,1,2-trifluoroéthane est généralement inférieur à 5. Il est de préférence inférieur à 3. Les rapports molaires de 0,8 à 2 sont tout particulièrement préférés.An advantageous physical expansion composition in the process according to the invention comprises a mixture of 1,1,2-trifluoroethane and chlorodifluoromethane. In this advantageous physical expansion composition, the chlorodifluoromethane / 1,1,2-trifluoroethane molar ratio is generally greater than 0.1. It is preferably greater than 0.3. Particularly preferably, it is greater than 0.5. This chlorodifluoromethane / 1,1,2-trifluoroethane molar ratio is generally less than 5. It is preferably less than 3. The molar ratios of 0.8 to 2 are very particularly preferred.
Parmi les autres agents gonflants, les hydrofluoroalcanes sont particulièrement préférés. Des hydrofluoroalcanes répondant à la formule générale CxFzH(2χ+2-z) -ui peuvent avantageusement être mis en oeuvre comme agents gonflants physiques autre que le 1,1,2-trifluoroéthane dans le procédé selon l'invention sont notamment le difluorométhane, le 1,1-difluoroéthane, le 1,1,1-trifluoroéthane, le 1,1,1,2-tétrafluoroéthane, le penta- fluoroéthane, le 1,1,1,2,3,3,3-heptafluoropropane, le 1,1,1,3,3- pentafluorobutane ou le 1,1,1,4,4,4-hexafluorobutane. Le 1,1,1,2-tétrafluoroéthane est tout particulièrement préféré. Une composition d'expansion physique tout particulièrement préférée dans le procédé selon l'invention comprend un mélange de 1,1,2- trifluoroéthane et de 1,1,1,2-tétrafluoroéthane. Dans cette composition d'expansion physique tout particulièrement préférée, le rapport molaire 1,1,1,2-tétrafluoroéthane / 1,1,2-trifluoro- éthane est généralement supérieur à 0,1. Il est de préférence supérieur à 0,3. De manière particulièrement préférée, il est supérieur à 0,5. De manière tout particulièrement préférée, il est supérieur à 0,7. Ce rapport molaire 1,1,1,2-tétrafluoro- éthane / 1,1,2-trifluoroéthane est généralement inférieur à 8. Il est de préférence inférieur à 5. De manière particulièrement préférée, il est inférieur à 3. Les rapports molaires de 0,8 à 2 sont tout particulièrement préférés. Lorsque la composition d'expansion physique comprend un agent gonflant autre que le 1,1,2-trifluoroéthane ininflammable, la proportion entre le 1,1,2-trifluoroéthane et cet agent gonflant est de préférence réglée de manière telle que la compo¬ sition d'expansion soit ininflammable. Dans le cas de la compo- sition d'expansion physique tout particulièrement préférée comprenant un mélange de 1,1,2-trifluoroéthane et de 1,1,1,2-tétrafluoroéthane, la composition est ininflammable lorsque le rapport molaire 1,1,1,2-tétrafluoroéthane / 1,1,2-trifluoroéthane est supérieur à 0,55. Dans le procédé selon l'invention, les matériaux polymé¬ riques cellulaires sont obtenus par mise en contact intime de la composition d'expansion avec une composition à expanser. Selon la nature des matériaux cellulaires fabriqués, la composition à expanser renferme soit des monomères réactifs, formant le matériau polymérique par polymérisation, soit le polymère d'ores et déjà synthétisé. La composition à expanser peut renfermer divers additifs, tels que des surfactants, des stabilisants, etc. Lorsque la composition à expanser contient les monomères réactifs, elle renferme généralement en outre d'autres additifs utiles à la polymérisation.Among the other blowing agents, hydrofluoroalkanes are particularly preferred. Hydrofluoroalkanes corresponding to the general formula C x F z H (2χ + 2-z) - u i can advantageously be used as physical blowing agents other than 1,1,2-trifluoroethane in the process according to the invention are in particular difluoromethane, 1,1-difluoroethane, 1,1,1-trifluoroethane, 1,1,1,2-tetrafluoroethane, pentafluoroethane, 1,1,1,2,3,3,3 -heptafluoropropane, 1,1,1,3,3- pentafluorobutane or 1,1,1,4,4,4-hexafluorobutane. The 1,1,1,2-tetrafluoroethane is very particularly preferred. A physical expansion composition very particularly preferred in the process according to the invention comprises a mixture of 1,1,2-trifluoroethane and 1,1,1,2-tetrafluoroethane. In this very particularly preferred physical expansion composition, the 1,1,1,2-tetrafluoroethane / 1,1,2-trifluoroethane molar ratio is generally greater than 0.1. It is preferably greater than 0.3. In a particularly preferred manner, it is greater than 0.5. Very particularly preferably, it is greater than 0.7. This 1,1,1,2-tetrafluoroethane / 1,1,2-trifluoroethane molar ratio is generally less than 8. It is preferably less than 5. In a particularly preferred manner, it is less than 3. The molar ratios from 0.8 to 2 are very particularly preferred. When the physical expansion composition comprises a swelling agent other than the non-flammable 1,1,2-trifluoroethane, the proportion between 1,1,2-trifluoroethane and this swelling agent is preferably adjusted in such a way that the composition expansion is non-flammable. In the case of the very particularly preferred physical expansion composition comprising a mixture of 1,1,2-trifluoroethane and 1,1,1,2-tetrafluoroethane, the composition is non-flammable when the molar ratio 1.1, 1,2-tetrafluoroethane / 1,1,2-trifluoroethane is greater than 0.55. In the process according to the invention, the cellular polymeric materials are obtained by bringing the expansion composition into intimate contact with a composition to be expanded. Depending on the nature of the cellular materials produced, the composition to be expanded contains either reactive monomers, forming the polymeric material by polymerization, or the polymer already synthesized. The composition to be expanded may contain various additives, such as surfactants, stabilizers, etc. When the composition to be expanded contains the reactive monomers, it generally also contains other additives useful for polymerization.
Dans certains cas, tels que dans les procédés de préparation de mousses de polyurethane, on peut, à titre auxiliaire, recourir en outre à un agent gonflant chimique constitué d'un composé gazeux généré chimiquement in situ, dans la composition à expanser, par la réaction de précurseurs de ce composé gazeux avec certains constituants précurseurs du matériau polymérique.In some cases, such as in preparation processes polyurethane foams, it is also possible, as an auxiliary, to use a chemical swelling agent consisting of a gaseous compound chemically generated in situ, in the composition to be expanded, by the reaction of precursors of this gaseous compound with certain precursor constituents polymeric material.
Le dioxyde de carbone, généré par réaction de l'eau avec un excès d'isocyanate, est un agent gonflant chimique préféré. Par rapport aux procédés antérieurs, le procédé selon l'invention permet d'obtenir des matériaux polymériques cellulaires de très bonne qualité au moyen d'agents gonflants physiques ayant un ODP nul, sans devoir mettre conjointement en oeuvre un agent gonflant chimique en proportion majoritaire. La proportion d'agent gonflant chimique dans la composition du gaz occupant les cellules des matériaux polymériques cellulaires obtenus par le procédé selon l'invention peut varier dans de larges mesures.Carbon dioxide, generated by the reaction of water with an excess of isocyanate, is a preferred chemical blowing agent. Compared to the previous methods, the method according to the invention makes it possible to obtain cellular polymeric materials of very good quality by means of physical blowing agents having a zero ODP, without having to jointly use a chemical blowing agent in the majority proportion. The proportion of chemical blowing agent in the composition of the gas occupying the cells of the cellular polymeric materials obtained by the process according to the invention can vary within wide limits.
Habituellement, elle ne dépasse pas 50 X molaire. De préférence, elle ne dépasse pas 40 X molaire. De manière particulièrement préférée, elle ne dépasse pas 35 X molaire. Lorsque le procédé selon l'invention est appliqué à la préparation de mousses de polyurethane, la proportion molaire de ces agents gonflants chimiques dans la composition du gaz occupant les cellules des mousses est le plus souvent supérieure à 5 % molaire, de préfé¬ rence, supérieure à 10 X molaire.Usually, it does not exceed 50 X molar. Preferably, it does not exceed 40 X molar. In a particularly preferred manner, it does not exceed 35 X molar. When the process according to the invention is applied to the preparation of polyurethane foams, the molar proportion of these chemical blowing agents in the composition of the gas occupying the foam cells is most often greater than 5 mol%, preferably, greater than 10 X molar.
La composition d'expansion physique est mise en oeuvre dans le procédé selon l'invention en une quantité adaptée à la densité du matériau polymérique cellulaire que l'on cherche à obtenir. Il est possible de préparer, grâce au procédé selon l'invention, des matériaux polymériques cellulaires de densité variant entre 10 et 200 kg/π.3, de préférence entre 15 et 100 kg/m^, de manière particulièrement préférée entre 20 et 80 kg/m^. La quantité de la composition d'expansion physique à mettre en oeuvre dans le procédé selon l'invention varie aussi selon la nature du matériau polymérique, selon la technique utilisée pour la mise en forme du matériau, selon que la mousse désirée est une mousse rigide ou flexible, etc. Généralement, la quantité de la composition d'expansion physique à mettre en oeuvre peut être facilement déterminée par l'homme du métier. En règle générale, la compo¬ sition d'expansion physique est avantageusement présente en quantité de 0,5 à 20 % du poids total de la composition à expanser et de la composition d'expansion physique. De préfé- rence, la composition d'expansion physique est présente en quantité de 1 à 18 % du poids total de la composition à expanser et de la composition d'expansion physique. De manière particu¬ lièrement préférée, elle est présente en quantité de 1,5 à 15 X du poids total de la composition à expanser et de la composition d'expansion physique. De manière tout particulièrement préférée, elle est présente en quantité de 2 à 12 % du poids total de la composition à expanser et de la composition d'expansion physique.The physical expansion composition is used in the process according to the invention in an amount adapted to the density of the cellular polymeric material that it is desired to obtain. It is possible to prepare, using the process according to the invention, cellular polymeric materials with a density varying between 10 and 200 kg / π.3, preferably between 15 and 100 kg / m ^, particularly preferably between 20 and 80 kg / m ^. The quantity of the physical expansion composition to be used in the process according to the invention also varies according to the nature of the polymeric material, according to the technique used for shaping the material, according to whether the desired foam is a rigid foam. or flexible, etc. Generally, the amount of the physical expansion composition to be used can be easily determined by those skilled in the art. As a general rule, the composition of physical expansion is advantageously present in an amount of 0.5 to 20% of the total weight of the composition to be expanded and of the composition of physical expansion. Preferably, the physical expansion composition is present in an amount of 1 to 18% of the total weight of the composition to be expanded and of the physical expansion composition. Particularly preferably, it is present in an amount of 1.5 to 15% of the total weight of the composition to be expanded and of the physical expansion composition. Most preferably, it is present in an amount of 2 to 12% of the total weight of the composition to be expanded and of the physical expansion composition.
L'emploi de compositions d'expansion physique selon l'invention est possible dans les différents procédés de prépa- ration de matériaux polymériques cellulaires, notamment dans les procédés connus de préparation de mousses polymériques dans lesquels les réactifs monomériques sont d'abord mélangés avec la composition d'expansion physique, éventuellement conservés sous forme de prémélanges, puis ensuite polymérisés, le caractère exothermique de la réaction entraînant la vaporisation de la composition d'expansion physique, ce qui provoque l'expansion du matériau polymérique. L'emploi des compositions d'expansion physique selon l'invention est aussi possible dans d'autres procédés d'expansion connus, consistant en l'injection sous pression de la composition d'expansion physique à l'état liquide dans le matériau polymérique, suivie d'une décompression qui provoque le passage de la composition d'expansion physique sous forme gazeuse et, de ce fait, l'expansion du matériau poly¬ mérique. A titre d'exemples de matériaux polymériques cellulaires qui peuvent être produits par le procédé selon l'invention, on peut mentionner les matériaux suivants : les polyuréthanes, les poly¬ amides, les polysulfones, les polyoléfines, telles que le poly- éthylène et le polypropylène, le polystyrène, le polycarbonate, le polyéthylène téréphtalate, le polychlorure de vinyle, les résines phénoliques, et les copolymères de ces différents matériaux. Différentes techniques de mise en oeuvre bien connues permettant de fabriquer ces matériaux cellulaires sont décrites, par exemple, dans "Encyclopédie of Polymer Science and Engineering", Vol. 3, 1985, pages 1 à 60. Le procédé selon l'invention peut avantageusement être appliqué à la préparation de polystyrène cellulaire. On a en effet observé que le 1,1,2-trifluoroéthane présente une solubilité satisfaisante dans le polystyrène. Des matériaux cellulaires en polystyrène peuvent être préparés en mettant en oeuvre des méthodes conventionnelles d'extrusion. Typiquement, une composition d'expansion physique comprenant du 1,1,2-tri- fluoroéthane est injectée sous pression dans un flux de poly¬ styrène plastifié par chauffage, à l'intérieur d'une extrudeuse, la décompression obtenue à la sortie de l'extrudeuse entraînant le passage de l'agent gonflant physique sous forme gazeuse et, de ce fait, l'expansion du polystyrène par soufflage.The use of physical expansion compositions according to the invention is possible in the various processes for the preparation of cellular polymeric materials, in particular in the known processes for the preparation of polymeric foams in which the monomeric reagents are first mixed with the physical expansion composition, optionally kept in the form of premixes, then subsequently polymerized, the exothermic nature of the reaction causing the vaporization of the physical expansion composition, which causes the expansion of the polymeric material. The use of the physical expansion compositions according to the invention is also possible in other known expansion methods, consisting in the injection under pressure of the physical expansion composition in the liquid state into the polymeric material, followed by decompression which causes the passage of the physical expansion composition in gaseous form and, therefore, the expansion of the polymeric material. By way of examples of cellular polymeric materials which can be produced by the process according to the invention, mention may be made of the following materials: polyurethanes, poly¬ amides, polysulfones, polyolefins, such as polyethylene and polypropylene, polystyrene, polycarbonate, polyethylene terephthalate, polyvinyl chloride, phenolic resins, and the copolymers of these various materials. Various well-known processing techniques for manufacturing these cellular materials are described, for example, in "Encyclopedia of Polymer Science and Engineering", Vol. 3, 1985, pages 1 to 60. The process according to the invention can advantageously be applied to the preparation of cellular polystyrene. It has in fact been observed that 1,1,2-trifluoroethane has a satisfactory solubility in polystyrene. Cellular polystyrene materials can be prepared using conventional extrusion methods. Typically, a physical expansion composition comprising 1,1,2-trifluoroethane is injected under pressure into a flow of plasticized poly¬ styrene by heating, inside an extruder, the decompression obtained at the outlet of the extruder causing the physical blowing agent to pass in gaseous form and, therefore, the expansion of the polystyrene by blowing.
Les compositions d'expansion physique comprenant du 1,1,2-trifluoroéthane et du chlorodifluorométhane apparaissent particulièrement intéressantes pour la production de mousses de polystyrène. On a en effet observé que la présence de chloro¬ difluorométhane provoque une augmentation importante de la solubilité du 1,1,2-trifluoroéthane dans le polystyrène.The physical expansion compositions comprising 1,1,2-trifluoroethane and chlorodifluoromethane appear particularly advantageous for the production of polystyrene foams. It has in fact been observed that the presence of chloro¬ difluoromethane causes a significant increase in the solubility of 1,1,2-trifluoroethane in polystyrene.
Dans la production de mousses de polystyrène, la composition d'expansion physique est typiquement mise en oeuvre à raison de 5 à 20 % du poids du polymère.In the production of polystyrene foams, the physical expansion composition is typically used at a rate of 5 to 20% by weight of the polymer.
Des résultats particulièrement intéressants ont été obtenus lorsque le procédé de l'invention est appliqué à la préparation de mousses de polyurethane. On a en effet observé que le 1,1,2-trifluoroéthane est particulièrement soluble dans les polyols mis en oeuvre dans la préparation des mousses de poly¬ urethane et qu'une proportion importante du 1,1,2-trifluoroéthane mis en oeuvre agit effectivement comme agent gonflant. On peut dès lors obtenir des matériaux cellulaires de densité souhaitée sans devoir travailler à une pression élevée ou avec des quantités trop importantes de la composition d'expansion physique. Le phénomène de moussage (frothing) est très limité, voire inexistant. De plus, les mousses obtenues par le procédé selon l'invention possèdent une proportion de cellules ouvertes très faible, voire nulle. Il en résulte l'obtention aisée d'un matériau cellulaire présentant une conductibilité thermique faible et une résistance mécanique élevée.Particularly interesting results have been obtained when the process of the invention is applied to the preparation of polyurethane foams. It has in fact been observed that 1,1,2-trifluoroethane is particularly soluble in the polyols used in the preparation of polyurethane foams and that a large proportion of the 1,1,2-trifluoroethane used acts effectively as a blowing agent. Cellular materials of desired density can therefore be obtained without having to work at high pressure or with excessively large amounts of the physical expansion composition. The frothing phenomenon is very limited, even non-existent. In addition, the foams obtained by the process according to the invention have a very low proportion of open cells, even zero. This results in the easy obtaining of a cellular material having a low thermal conductivity and a high mechanical resistance.
De manière très surprenante, on a observé en outre, dans la préparation de mousses de polyurethane, que lorsque la compo¬ sition d'expansion physique comprend un mélange de 1,1,2-tri- fluoroéthane et de 1,1,1,2-tétrafluoroéthane, la quantité de 1,1,1,2-tétrafluoroéthane dissoute dans le polyol, à température et pression identiques, est plus importante que lorsque ce produit est utilisé seul. Lorsque la composition d'expansion physique comprend un mélange de 1,1,2-trifluoroéthane et de 1,1,1,2-tétrafluoroéthane, la quantité de 1,1,1,2- tetrafluoroethane qui reste dans la mousse, c'est-à-dire qui agit effectivement comme agent gonflant, est beaucoup plus importante que lorsque ce produit est utilisé seul. Il en résulte que le procédé de l'invention permet de préparer des mousses de poly¬ urethane d'excellente qualité de manière plus aisée que les procédés dans lesquels le 1,1,1 ,2-tétrafluoroéthane est le seul hydrofluoroalcane utilisé comme agent gonflant physique.Very surprisingly, it has also been observed, in the preparation of polyurethane foams, that when the composition of physical expansion comprises a mixture of 1,1,2-trifluoroethane and 1,1,1, 2-tetrafluoroethane, the quantity of 1,1,1,2-tetrafluoroethane dissolved in the polyol, at identical temperature and pressure, is greater than when this product is used alone. When the physical expansion composition comprises a mixture of 1,1,2,2-trifluoroethane and 1,1,1,2-tetrafluoroethane, the amount of 1,1,1,2- tetrafluoroethane which remains in the foam is that is, which actually acts as a blowing agent, is much more important than when this product is used alone. As a result, the process of the invention makes it possible to prepare polyurethane foams of excellent quality more easily than the processes in which 1,1,1,2-tetrafluoroethane is the only hydrofluoroalkane used as swelling agent. physical.
Par polyurethane, on entend désigner aux fins de la présente invention tous les polymères issus de la réaction de polyols et d'isocyanates comprenant des fonctions uréthanes :The term “polyurethane” is intended to denote, for the purposes of the present invention, all the polymers resulting from the reaction of polyols and isocyanates comprising urethane functions:
00
MM
_ NH _ C _ 0 " Le vocable "polyurethane" englobe donc les polymères issus de la réaction de polyols et d'isocyanates qui contiennent outre des fonctions uréthanes d'autres types de fonctions, telles que par exemple des fonctions isocyanuriques 0 _ NH _ C _ 0 " The term" polyurethane "therefore includes polymers resulting from the reaction of polyols and isocyanates which contain, in addition to urethane functions, other types of function, such as for example isocyanuric functions 0
IIII
CVS
/ \/ \
- N N _ - NN _
I I 0 = C C = 0I I 0 = C C = 0
\ /\ /
NNOT
I habituellement désignés sous le vocable "polyurethane modifié" ou "polyisocyanurate". Il est bien connu que l'obtention de poly¬ urethane ou de polyurethane "modifié" dépend essentiellement de l'excès d'isocyanate mis en oeuvre, ainsi que du type de cata- lyseur utilisé.I usually designated by the term "modified polyurethane" or "polyisocyanurate". It is well known that obtaining poly¬ urethane or "modified" polyurethane essentially depends on the excess of isocyanate used, as well as on the type of catalyst used.
Selon l'invention, les mousses de polyurethane telles que définies ci-dessus sont obtenues par réaction et expansion de polyols et d'isocyanates en présence des ingrédients usuels bien connus de l'homme de l'art et de la composition d'expansion physique. Une large gamme de polyols déjà divulgués dans l'art antérieur peut être utilisée, comprenant notamment les polyethers polyols et les polyesters polyols. De même, une large gamme d'isocyanates déjà divulgués dans l'art antérieur peut être utilisée dans le procédé de l'invention. Des isocyanates classiquement mis en oeuvre sont, par exemple, des isocyanates aliphatiques, tels que le diisocyanate d'hexaméthylène et des isocyanates aromatiques, tels que le diisocyanate de tolylène ou le diisocyanate de diphénylméthane (MDI).According to the invention, the polyurethane foams as defined above are obtained by reaction and expansion of polyols and isocyanates in the presence of the usual ingredients well known to those skilled in the art and of the physical expansion composition . A wide range of polyols already disclosed in the prior art can be used, including in particular polyether polyols and polyester polyols. Likewise, a wide range of isocyanates already disclosed in the prior art can be used in the process of the invention. Isocyanates conventionally used are, for example, aliphatic isocyanates, such as hexamethylene diisocyanate and aromatic isocyanates, such as tolylene diisocyanate or diphenylmethane diisocyanate (MDI).
Comme il est bien connu, la réaction de polymérisation nécessite la présence d'un catalyseur. N'importe quel catalyseur habituellement utilisé dans les procédés antérieurs de prépa¬ ration de mousses de polyurethane convient au procédé selon l'invention. On peut citer les composés aminés comme, par exemple, la N,N-diméthylcyclohexylamine (DMCHA), la N-méthyl- morpholine (NMM), la N,N-diméthylbenzylamine (DB), la triéthyl- amine, la N,N,N' ,N'-tétraméthylènediamine, la diméthyléthanolamine, la triéthylènediamine ou encore les composés de métaux lourds comme des composés d'étain ou de plomb. En général, la quantité de catalyseur utilisée varie d'environ 0,05 X à environ 2 X en poids par rapport à la quantité de polyol mis en oeuvre.As is well known, the polymerization reaction requires the presence of a catalyst. Any catalyst usually used in the previous processes for the preparation of polyurethane foams is suitable for the process according to the invention. One can cite the amino compounds such as, for example, N, N-dimethylcyclohexylamine (DMCHA), N-methylmorpholine (NMM), N, N-dimethylbenzylamine (DB), triethylamine, N, N , N ', N'-tetramethylenediamine, la dimethylethanolamine, triethylenediamine or even heavy metal compounds such as tin or lead compounds. In general, the amount of catalyst used varies from about 0.05 X to about 2 X by weight relative to the amount of polyol used.
En fonction des caractéristiques désirées pour le matériau cellulaire, de nombreux autres additifs peuvent être incorporés dans la composition à expanser, notamment de l'eau, des stabi¬ lisants, des surfactants comme des huiles de silicone, des agents réticulants, comme la glycérine, des agents plastifiants, des agents antioxydants et des agents retardateurs de flamme.Depending on the characteristics desired for the cellular material, numerous other additives can be incorporated into the composition to be expanded, in particular water, stabilizers, surfactants such as silicone oils, crosslinking agents, such as glycerin, plasticizers, antioxidants and flame retardants.
La quantité d'eau mise en oeuvre est adaptée à la proportion de dioxyde de carbone souhaitée dans la composition du gaz occupant les cellules des mousses obtenues par le procédé selon l'invention.The amount of water used is adapted to the proportion of carbon dioxide desired in the composition of the gas occupying the cells of the foams obtained by the process according to the invention.
Lorsque le procédé selon l'invention est appliqué aux mousses de polyurethane, celles-ci sont préparées par réaction des monomères (polyols et isocyanates) contenus dans la compo¬ sition à expanser, avec les différents additifs, dans les proportions requises, en présence de la composition d'expansion physique. En pratique, il est commode de mettre en oeuvre des prémélanges dans lesquels la composition d'expansion physique et divers additifs sont combinés avec un des monomères réactifs, le plus souvent avec le polyol, éventuellement conservés sous cette forme pendant un certain temps, puis mélangés avec l'autre mono¬ mère réactif juste avant la préparation de la mousse. Les réac¬ tions de polymérisation, d'expansion et de durcissement et les conditions dans lesquelles sont menées ces réactions sont bien connues dans l'art antérieur et ne sont quasiment pas affectées par l'utilisation de 1,1,2-trifluoroéthane comme agent gonflant physique.When the process according to the invention is applied to polyurethane foams, these are prepared by reaction of the monomers (polyols and isocyanates) contained in the composition to be expanded, with the various additives, in the required proportions, in the presence of the composition of physical expansion. In practice, it is convenient to use premixes in which the physical expansion composition and various additives are combined with one of the reactive monomers, most often with the polyol, optionally kept in this form for a certain time, then mixed. with the other reactive monomer just before the preparation of the foam. The polymerization, expansion and hardening reactions and the conditions under which these reactions are carried out are well known in the prior art and are hardly affected by the use of 1,1,2-trifluoroethane as agent bulging physical.
L'invention concerne également des prémélanges utilisables pour la préparation de mousses de polyurethane, comprenant au moins un polyol et une composition d'expansion physique, qui se caractérisent en ce que la composition d'expansion physique comprend du 1,1,2-trifluoroéthane. Les prémélanges selon l'invention peuvent éventuellement comprendre d'autres agents gonflants, tels que définis plus haut.The invention also relates to premixes which can be used for the preparation of polyurethane foams, comprising at least one polyol and one physical expansion composition, which are characterized in that the physical expansion composition comprises 1,1,2-trifluoroethane . Premixes according to the invention may optionally include other swelling agents, as defined above.
Les polyols compris dans les prémélanges selon l'invention sont typiquement les polyols classiquement mis en oeuvre dans la préparation de mousses de polyurethane, tels que des polyethers polyols et des polyesters polyols.The polyols included in the premixes according to the invention are typically the polyols conventionally used in the preparation of polyurethane foams, such as polyether polyols and polyester polyols.
Classiquement, les prémélanges selon l'invention peuvent comprendre en outre divers additifs choisis parmi les catalyseurs de polymérisation, les stabilisants, les surfactants tels que les huiles de silicone, les agents réticulants tels que la glycérine, les agents plastifiants, les agents antioxydants et les agents retardateurs de flamme.Conventionally, the premixes according to the invention can also comprise various additives chosen from polymerization catalysts, stabilizers, surfactants such as silicone oils, crosslinking agents such as glycerin, plasticizers, antioxidants and flame retardants.
La composition d'expansion physique constitue généralement de 1 à 30 X, de préférence de 2 à 25 _, du poids du prémélange. Les prémélanges selon l'invention présentent, à même quantité molaire globale de la composition d'expansion physique, une tension de vapeur très nettement inférieure à celle de prémélanges renfermant du 1,1,1,2-tetrafluoroethane comme seul agent gonflant physique. Leur manipulation et leur stockage s'en trouvent fortement facilités.The physical expansion composition generally constitutes from 1 to 30%, preferably from 2 to 25%, of the weight of the premix. The premixes according to the invention have, at the same overall molar amount of the physical expansion composition, a vapor pressure very much lower than that of premixes containing 1,1,1,2-tetrafluoroethane as the sole physical blowing agent. Their handling and storage are greatly facilitated.
Les exemples suivants illustrent l'invention. Les exemples réalisés à titre de comparaison sont annotés (C). Exemples 1 à 4The following examples illustrate the invention. The examples made for comparison are annotated (C). Examples 1 to 4
Dans l'exemple 1, une mousse de polyurethane rigide a été préparée au départ d'une composition comprenant un diisocyanate de diphénylméthane polymérique DESMODUR-y 44V20 commercialisé par BAYER, un polyol aminé ARCOI® 3770 commercialisé par ARCO, un surfactant silicone TEGOSTAB-VB 1048 commercialisé par Th. GOLDSCHMIDT, de la N-méthylmorpholine (NMM), de l'eau et une composition d'expansion constituée exclusivement de 1,1,2-tri- fluoroéthane. Le diisocyanate de diphénylméthane (MDI) et le polyol ont été introduits dans des rapports tels que l'index soit de 110.In Example 1, a rigid polyurethane foam was prepared from a composition comprising a polymeric diphenylmethane diisocyanate DESMODUR- y 44V20 marketed by BAYER, an amino polyol ARCOI® 3770 marketed by ARCO, a silicone surfactant TEGOSTAB-VB 1048 marketed by Th. GOLDSCHMIDT, N-methylmorpholine (NMM), water and an expansion composition consisting exclusively of 1,1,2-trifluoroethane. Diphenylmethane diisocyanate (MDI) and polyol were introduced in ratios such that the index was 110.
Dans l'exemple 2, la composition d'expansion physique est constituée de 1,1,2-trifluoroéthane et de 1,1,1,2-tétrafluoro- éthane. A titre de comparaison, dans l'exemple 3(C), la composition d'expansion a consisté en 100 X de 1,1,1,2-tétrafluoroéthane et, dans l'exemple 4(C), en 100 X de trichlorofluorométhane (CFC-11). Les mousses ont été préparées par ajout progressif de la composition d'expansion physique préalablement liquéfiée par refroidissement, au mélange de tous les ingrédients à l'exception du MDI, préalablement refroidi à - 28 °C. Dans l'exemple 2, le 1,1,2-trifluoroéthane a d'abord été ajouté, puis ensuite le 1,1,1,2-tétrafluoroéthane. Dans l'exemple 3(C), du 1,1,1,2-tétrafluoroéthane a été ajouté en large excès, de manière à atteindre la limite de solubilité du 1,1,1,2-tétrafluoroéthane dans le polyol.In Example 2, the physical expansion composition consists of 1,1,2-trifluoroethane and 1,1,1,2-tetrafluoroethane. By way of comparison, in Example 3 (C), the expansion composition consisted of 100 X of 1,1,1,2-tetrafluoroethane and, in Example 4 (C), in 100 X of trichlorofluoromethane (CFC-11). The foams were prepared by progressive addition of the physical expansion composition previously liquefied by cooling, to the mixture of all the ingredients except for MDI, previously cooled to -28 ° C. In Example 2, 1,1,2-trifluoroethane was first added, and then 1,1,1,2-tetrafluoroethane. In Example 3 (C), 1,1,1,2-tetrafluoroethane was added in large excess, so as to reach the limit of solubility of 1,1,1,2-tetrafluoroethane in polyol.
Après addition de la composition d'expansion, la température du prémélange était, dans chaque cas, d'environ - 7 °C. La quantité d'agent gonflant physique dissoute dans le prémélange a été mesurée par pesée.After addition of the expansion composition, the temperature of the premix was, in each case, about - 7 ° C. The amount of physical blowing agent dissolved in the premix was measured by weighing.
Le MDI, préalablement refroidi à environ 3 °C, a ensuite été ajouté au prémélange. La composition obtenue a été mélangée intimement pendant 25 secondes au moyen d'un agitateur de type multipale tournant à 1600 tours par minute, puis transvasée dans un moule à expansion libre.The MDI, previously cooled to about 3 ° C, was then added to the premix. The composition obtained was thoroughly mixed for 25 seconds using a multi-blade type agitator rotating at 1600 revolutions per minute, then transferred to a free expansion mold.
Les formulations mises en oeuvre, les paramètres de réacti¬ vité, la teneur en agents gonflants dans la mousse et les propriétés des différentes mousses obtenues sont rassemblés au tableau I. Les quantités d'agents gonflants mises en oeuvre indiquées au tableau I correspondent aux quantités dissoutes dans le prémélange.The formulations used, the reactivity parameters, the content of swelling agents in the foam and the properties of the various foams obtained are collated in Table I. The quantities of blowing agents used indicated in Table I correspond to the quantities dissolved in the premix.
La quantité d'agents gonflants physiques retrouvée dans les mousses a été mesurée de la manière suivante. De petits échantillons de mousses ont été introduits dans un flacon pillulier fermé hermétiquement par un septum en caoutchouc, dans lequel ils sont broyés. La phase gazeuse est ensuite analysée par chromatographie en phase gazeuse. En raison d'effets de surface, les résultats obtenus par cette méthode représentent généralement une valeur inférieure à la quantité réellement présente dans la mousse. Des conclusions relatives peuvent néanmoins en être tirées.The amount of physical blowing agents found in the foams was measured as follows. Small samples of mosses were introduced into a pill bottle hermetically sealed by a rubber septum, in which they are ground. The gas phase is then analyzed by gas chromatography. Due to surface effects, the results obtained by this method generally represent a value lower than the quantity actually present in the foam. Relative conclusions may nevertheless be drawn from it.
Une comparaison des résultats des exemples 1 et 2 avec ceux de l'exemple 3(C) fait apparaître l'avantage lié à l'utilisation d'une composition comprenant du 1,1,2-trifluoroéthane pour ce qui concerne la légèreté de la mousse produite.A comparison of the results of Examples 1 and 2 with those of Example 3 (C) shows the advantage linked to the use of a composition comprising 1,1,2-trifluoroethane as regards the lightness of the foam produced.
Une comparaison des résultats des exemples 2 et 3(C) montre que, lorsque l'agent gonflant physique comprend un mélange de 1,1,2-trifluoroéthane et de 1,1,1,2-tétrafluoroéthane, la quantité de 1,1,1,2-tétrafluoroéthane dissoute dans le prémélange, à température et pression identiques, est plus impor¬ tante qu'en absence de 1,1,2-trifluoroéthane. De même, la quantité de 1,1,1,2-tétrafluoroéthane incorporée dans la mousse est plus importante en présence de 1,1,2-trifluoroéthane.A comparison of the results of Examples 2 and 3 (C) shows that, when the physical blowing agent comprises a mixture of 1,1,2-trifluoroethane and 1,1,1,2-tetrafluoroethane, the amount of 1.1 , 1,2-tetrafluoroethane dissolved in the premix, at identical temperature and pressure, is more important than in the absence of 1,1,2-trifluoroethane. Likewise, the quantity of 1,1,1,2-tetrafluoroethane incorporated into the foam is greater in the presence of 1,1,2-trifluoroethane.
Ces exemples montrent que, dans des conditions identiques de température et de pression, il est possible, de préparer des mousses de polyurethane de densité satisfaisante au moyen de HFC-143 ou d'un mélange de HFC-143 et de HFC-134a, comme agent gonflant physique. Cela n'est par contre pas possible avec du HFC-134a seul. Exemples 5 à 10These examples show that, under identical conditions of temperature and pressure, it is possible to prepare polyurethane foams of satisfactory density using HFC-143 or a mixture of HFC-143 and HFC-134a, as physical blowing agent. However, this is not possible with HFC-134a alone. EXAMPLES 5 TO 10
Des mousses de polyurethane rigide ont été préparées au moyen d'une machine basse pression ADMIRAL M8-2H permettant l'injection directe de la composition d'expansion physique dans la tête de mélange. La composition d'expansion physique prélevée en phase liquide a été introduite dans la tête de mélange à un débit contrôlé sous une pression de 20 bar. La machine était équipée soit d'un mélangeur mécanique classique (noté M dans le tableau II), soit d'un mélangeur statique hélicoïdal (noté S dans le tableau II). Les mousses ont été préparées au départ d'une composition comprenant un diisocyanate de diphénylméthane polymérique (MDI) DESM0DUR 44V20 commercialisé par BAYER, un polyol aminé sur base sucrose CARAD0I.B)585-8 commercialisé par SHELL, du trichloro- propylphosphate (TCPP), un surfactant silicone KACESTA^L commercialisé par S0LVAY FLUOR UND DERIVATE, un mélange de catalyseurs constitué de catalyseur DABC0_-)33LV commercialisé par AIR PRODUCTS et de diméthyléthanolamine, de l'eau et une compo¬ sition d'expansion dans des proportions pondérales détaillées au tableau II. Le MDI et le polyol ont été introduits dans des rapports tels que l'index soit de 110. Pour chaque mousse, on a mesuré la densité, le pourcentage de cellules fermées et la quantité d'agent gonflant retrouvée. Ces différentes caractéristiques sont rassemblées dans le tableau II.Rigid polyurethane foams were prepared using an ADMIRAL M8-2H low pressure machine allowing direct injection of the physical expansion composition into the mixing head. The physical expansion composition taken in the liquid phase was introduced into the mixing head at a controlled flow rate under a pressure of 20 bar. The machine was equipped either with a conventional mechanical mixer (denoted M in table II), or with a helical static mixer (denoted S in table II). The foams were prepared from a composition comprising a polymeric diphenylmethane diisocyanate (MDI) DESM0DUR 44V20 marketed by BAYER, an amino polyol based on sucrose CARAD0I.B) 585-8 marketed by SHELL, trichloropropylphosphate (TCPP) , a KACESTA ^ L silicone surfactant sold by S0LVAY FLUOR UND DERIVATE, a mixture of catalysts consisting of catalyst DABC0_- ) 33LV sold by AIR PRODUCTS and dimethylethanolamine, water and an expansion composition in the weight proportions detailed in Table II. The MDI and the polyol were introduced in reports such that the index was 110. For each foam, the density, the percentage of closed cells and the quantity of blowing agent found were measured. These different characteristics are collated in Table II.
Le pourcentage de cellules fermées a été déterminé selon la norme ASTM D1940.The percentage of closed cells was determined according to standard ASTM D1940.
La quantité d'agent gonflant retrouvée dans la mousse a été déterminée selon la même procédure que celle utilisée pour les exemples 1 à 4. Cette quantité est exprimée en pourcentage de la quantité théorique mise en oeuvre dans la formulation. La comparaison des résultats de l'exemple 5 avec ceux de l'exemple 6(C) et des résultats de l'exemple 7 avec ceux de l'exemple 8(C), différant uniquement par la nature de l'agent gonflant mis en oeuvre, fait apparaître les avantages liés à l'utilisation de 1,1,2-trifluoroéthane comme agent gonflant physique au lieu de 1,1,1,2-^étrafluoroéthane. Cette comparaison démontre qu'il est possible de préparer des mousses de poly¬ urethane de densité satisfaisante au moyen d'une machine d'injection basse pression, c'est-à-dire d'une machine fonctionnant classiquement à une pression de 2 à 30 bar, en uti- lisant des compositions d'expansion physique comprenant du 1,1,2- trifluoroéthane comme agent gonflant. Cela n'est par contre pas possible avec du 1,1,1,2-tétrafluoroéthane seul. L'exemple 9, à comparer aux exemples 6(C) et 8(C), démontre l'effet favorable du 1,1,2-trifluoroéthane sur la quantité du 1,1,1,2-tétrafluoro- éthane restant dans la mousse. Exemples 11 et 12The amount of blowing agent found in the foam was determined according to the same procedure as that used for Examples 1 to 4. This amount is expressed as a percentage of the theoretical amount used in the formulation. The comparison of the results of Example 5 with those of Example 6 (C) and of the results of Example 7 with those of Example 8 (C), differing only in the nature of the blowing agent used. work, shows the advantages of using 1,1,2-trifluoroethane as a physical blowing agent instead of 1,1,1,2- ^ etrafluoroethane. This comparison demonstrates that it is possible to prepare poly¬ urethane foams of satisfactory density by means of a low pressure injection machine, that is to say a machine conventionally operating at a pressure of 2 to 30 bar, using physical expansion compositions comprising 1,1,2-trifluoroethane as the blowing agent. However, this is not possible with 1,1,1,2-tetrafluoroethane alone. Example 9, compared with Examples 6 (C) and 8 (C), demonstrates the favorable effect of 1,1,2-trifluoroethane on the amount of 1,1,1,2-tetrafluoroethane remaining in the foam. Examples 11 and 12
La machine basse pression ADMIRAL M8-2H utilisée pour réa¬ liser les tests des exemples 5 à 10 a été équipée d'une station de prémélange de la composition d'expansion physique avec le polyol et d'un réservoir de stockage du prémélange sous pression de 2 bar. Deux mousses de polyurethane rigide ont été préparées par introduction dans la tête de mélange de la machine équipée d'un mélangeur mécanique, d'un isocyanate de diphénylméthane polymé¬ rique (MDI) et d'un prémélange contenant une composition d'expansion physique, un polyol aminé sur base sucrose, un poly- éther polyol brome IXOL B 251, un agent de réticulation hydro- xylé, ainsi qu'une petite quantité de surfactant silicone, d'additif phosphore retardateur de flamme et de catalyseur aminé. Le MDI et les polyols sont introduits dans des rapports tels que l'index 110 soit atteint.The ADMIRAL M8-2H low-pressure machine used to carry out the tests of Examples 5 to 10 was equipped with a station for premixing the physical expansion composition with the polyol and with a tank for storing the premix under pressure. of 2 bar. Two rigid polyurethane foams were prepared by introducing into the mixing head of the machine equipped with a mechanical mixer, a polymeric diphenylmethane isocyanate (MDI) and a premix containing a physical expansion composition, an amino polyol based on sucrose, a brominated polyether polyol IXOL B 251, a hydroxylated crosslinking agent, as well as a small amount of silicone surfactant, flame retardant phosphorous additive and amino catalyst. MDI and polyols are introduced in reports such that index 110 is reached.
Du 1,1-dichloro-l-fluoroéthane a été utilisé comme compo¬ sition d'expansion physique dans l'exemple 11(C) et du 1,1,2- trifluoroéthane dans l'exemple 12.1,1-Dichloro-1-fluoroethane was used as composition for physical expansion in Example 11 (C) and 1,1,2-trifluoroethane in Example 12.
Les formulations mises en oeuvre et les propriétés des mousses obtenues sont rassemblées au tableau III.The formulations used and the properties of the foams obtained are collated in Table III.
Les résultats de l'exemple 12 démontrent qu'il est possible de préparer des mousses de polyurethane rigide présentant des propriétés satisfaisantes au moyen d'une machine basse pression, selon la procédure classique mettant en oeuvre la composition d'expansion physique et le(s) polyol(s) sous la forme d'un prémé¬ lange. Ces résultats confirment en outre qu'une proportion importante du 1,1,2-trifluoroéthane mis en oeuvre comme agent gonflant reste effectivement dans la mousse, proportion supé¬ rieure à celle du 1,1-dichloro-l-fluoroéthane lorsque celui-ci est utilisé comme agent gonflant dans des conditions identiques. Exemples 13 à 22The results of Example 12 demonstrate that it is possible to prepare rigid polyurethane foams having satisfactory properties by means of a low-pressure machine, according to the conventional procedure using the physical expansion composition and the (s ) polyol (s) in the form of a premix. These results further confirm that a large proportion of the 1,1,2-trifluoroethane used as a blowing agent actually remains in the foam, a proportion greater than that of 1,1-dichloro-l-fluoroethane when the latter is used as a blowing agent under identical conditions. Examples 13 to 22
L'intérêt du procédé selon l'invention pour préparer des mousses de polystyrène a été estimé en mesurant la solubilité de différentes compositions d'expansion dans du polystyrène. Pour ce faire, on a introduit, dans un réacteur en acier inoxydable d'une capacité de 0,5 1, une nacelle constituée d'un tamis en acier inoxydable et contenant des granulés de polystyrène VESTYROt® type 114 de HULS AG, recouverts de billes de verre. Le réacteur a été mis sous vide et refroidi à -70° C puis une compo- sition d'expansion physique constituée d'un ou de deux hydro- (chloro)fluoroalcanes a été introduite dans le réacteur en une quantité suffisante pour immerger tous les granulés de polystyrène. Après 2 jours et demi à température constante, la teneur en hydro(chloro)fluoroalcane(s) dans les granulés de poly¬ styrène a été déterminée. Les résultats obtenus pour différentes compositions d'expansion sont présentés dans le tableau IV.The advantage of the process according to the invention for preparing polystyrene foams has been estimated by measuring the solubility of different expansion compositions in polystyrene. To do this, a nacelle consisting of a stainless steel screen and containing VESTYROt® polystyrene granules type 114 from HULS AG, covered with a 0.5 l capacity, was introduced into a stainless steel reactor with a capacity of 0.5 l. glass marbles. The reactor was placed under vacuum and cooled to -70 ° C. then a physical expansion composition consisting of one or two hydro- (chloro) fluoroalkanes was introduced into the reactor in one sufficient to immerse all the polystyrene granules. After 2 and a half days at constant temperature, the content of hydro (chloro) fluoroalkane (s) in the polystyrene granules was determined. The results obtained for different expansion compositions are presented in Table IV.
Le chlorodifluorométhane et le l-chloro-l,l-difluoroéthane, agents gonflants classiques du polystyrène présentent une très bonne solubilité dans le polystyrène (exemples 13(C) à 16(C)). Ces composés contiennent cependant du chlore et leur utilisation sera à l'avenir de plus en plus réglementée. Le 1,1,2-trifluoro¬ éthane présente à température ambiante une solubilité nettement plus faible que ces composés classiques (exemple 17) mais on a observé que la solubilité du 1,1,2-trifluoroéthane augmente beaucoup plus rapidement avec la température que la solubilité du chlorodifluorométhane ou du l-chloro-l,l-difluoroéthane. A 80 °C, on a mesuré une teneur de 11,3 X en poids de 1,1,2- trifluoroéthane dans le polystyrène (exemple 18). Le 1,1,1,2- tétrafluoroéthane apparaît par contre très peu soluble dans le polystyrène, tant à température ambiante (exemple 19(C)) qu'à 80 °C (exemple 20(C)).Chlorodifluoromethane and l-chloro-l, l-difluoroethane, conventional swelling agents of polystyrene have very good solubility in polystyrene (Examples 13 (C) to 16 (C)). However, these compounds contain chlorine and their use will be increasingly regulated in the future. 1,1,2-trifluoro¬ ethane has a significantly lower solubility at room temperature than these conventional compounds (Example 17) but it has been observed that the solubility of 1,1,2-trifluoroethane increases much more rapidly with temperature than the solubility of chlorodifluoromethane or l-chloro-l, l-difluoroethane. At 80 ° C, a content of 11.3 X by weight of 1,1,2-trifluoroethane in the polystyrene was measured (Example 18). 1,1,1,2-tetrafluoroethane, on the other hand, appears to be very sparingly soluble in polystyrene, both at room temperature (example 19 (C)) and at 80 ° C (example 20 (C)).
La comparaison des exemples 21 et 22(C) démontre le compor¬ tement particulièrement intéressant des compositions d'expansion selon l'invention contenant du 1,1,2-trifluoroéthane et du chlorodifluorométhane. Alors que la présence de 1,1,1,2-tétra- fluoroéthane dans la composition d'expansion provoque une dimi¬ nution importante de la solubilité du chlorodifluorométhane dans le polystyrène (exemple 22(C)), la présence simultanée de 1,1,2- trifluoroéthane et de chlorodifluorométhane dans la composition d'expansion provoque une forte augmentation de la solubilité du 1,1,2-trifluoroéthane, sans affecter la solubilité du chloro¬ difluorométhane (exemple 21). TABLEAU IThe comparison of Examples 21 and 22 (C) demonstrates the particularly advantageous behavior of the expansion compositions according to the invention containing 1,1,2-trifluoroethane and chlorodifluoromethane. While the presence of 1,1,1,2-tetrafluoroethane in the expansion composition causes a significant reduction in the solubility of chlorodifluoromethane in polystyrene (example 22 (C)), the simultaneous presence of 1, 1,2-trifluoroethane and chlorodifluoromethane in the expansion composition causes a large increase in the solubility of 1,1,2-trifluoroethane, without affecting the solubility of chloro-difluoromethane (Example 21). TABLE I
Figure imgf000020_0001
Figure imgf000020_0001
(1) quantité théorique; (2) quantité mesurée TABLEAU II(1) theoretical quantity; (2) quantity measured TABLE II
Figure imgf000021_0001
Figure imgf000021_0001
TABLEAU IIITABLE III
Figure imgf000022_0001
TABLEAU IV
Figure imgf000022_0001
TABLE IV
Figure imgf000023_0001
Figure imgf000023_0001

Claims

R E V E N D I C A T I O N SR E V E N D I C A T I O N S
1 - Procédé de préparation d'un matériau polymérique cellulaire selon lequel on traite une composition à expanser en présence d'une composition d'expansion physique, caractérisé en1 - Process for the preparation of a cellular polymeric material according to which a composition to be expanded is treated in the presence of a composition for physical expansion, characterized in
5 ce que la composition d'expansion comprend du 1,1,2-trifluoro¬ éthane.5 that the expansion composition comprises 1,1,2-trifluoro¬ ethane.
2 - Procédé selon la revendication 1 dans lequel la composition d'expansion comprend en outre un hydrochlorofluoro- alcane ou un hydrofluoroalcane autre que le 1,1,2-trifluoro-2 - Process according to claim 1 wherein the expansion composition further comprises a hydrochlorofluoroalkane or a hydrofluoroalkane other than 1,1,2-trifluoro-
!0 éthane.! 0 ethane.
3 - Procédé selon la revendication 2 dans lequel l'hydro- chlorofluoroalcane est le chlorodifluorométhane.3 - Process according to claim 2 wherein the hydrochlorofluoroalkane is chlorodifluoromethane.
4 - Procédé selon la revendication 3 dans lequel la composition d'expansion comprend le 1,1,2-trifluoroéthane et le4 - Process according to claim 3 wherein the expansion composition comprises 1,1,2-trifluoroethane and
'5 chlorodifluorométhane dans un rapport molaire chlorodifluoro- méthane/1,1,2-trifluoroéthane compris entre 0,1 et 5.'5 chlorodifluoromethane in a chlorodifluoromethane / 1,1,2-trifluoroethane molar ratio of between 0.1 and 5.
5 - Procédé selon la revendication 2 dans lequel l'hydro¬ fluoroalcane autre que le 1,1,2-trifluoroéthane répond à la formule générale CxFzH(2χ+2-z) dans laquelle x représente un 0 nombre entier de 1 à 4 et z un nombre entier de x à 2x+l.5 - Process according to claim 2 wherein the hydro¬ fluoroalkane other than 1,1,2-trifluoroethane corresponds to the general formula C x F z H (2χ + 2-z) in which x represents a whole number of 0 1 to 4 and z an integer from x to 2x + l.
6 - Procédé selon la revendication 5 dans lequel l'hydro¬ fluoroalcane est le 1,1,1,2-tétrafluoroéthane.6 - Process according to claim 5 wherein the hydro¬ fluoroalkane is 1,1,1,2-tetrafluoroethane.
7 - Procédé selon la revendication 6 dans lequel la compo¬ sition d'expansion comprend le 1,1,2-trifluoroéthane et le 5 1,1,1,2-tétrafluoroéthane dans un rapport molaire 1,1,1,2-tétra- fluoroéthane / 1,1,2-trifluoroéthane compris entre 0,1 et 8.7 - Process according to claim 6 wherein the expansion composition comprises 1,1,2-trifluoroethane and 5 1,1,1,2-tetrafluoroethane in a 1,1,1,2-tetra molar ratio - fluoroethane / 1,1,2-trifluoroethane between 0.1 and 8.
8 - Procédé selon l'une quelconque des revendications 1 à 7, dans lequel la composition d'expansion est présente en quantité de 0,5 à 20 % du poids total de la composition à expanser et de8 - Method according to any one of claims 1 to 7, wherein the expansion composition is present in an amount of 0.5 to 20% of the total weight of the composition to be expanded and
30 la composition d'expansion. 9 - Procédé selon une quelconque des revendications 1 à 8 dans lequel le matériau polymérique cellulaire est une mousse de polyurethane.30 the expansion composition. 9 - Process according to any one of claims 1 to 8 wherein the cellular polymeric material is a polyurethane foam.
10 - Procédé selon une quelconque des revendications 1 à 8 dans lequel le matériau polymérique cellulaire est une mousse de polystyrène.10 - Process according to any one of claims 1 to 8 wherein the cellular polymeric material is a polystyrene foam.
11 - Prémélanges utilisables pour la préparation de mousses de polyurethane, comprenant au moins un polyol et une composition d'expansion physique, caractérisés en ce que la composition d'expansion comprend du 1,1,2-trifluoroéthane. 11 - Premixes which can be used for the preparation of polyurethane foams, comprising at least one polyol and one physical expansion composition, characterized in that the expansion composition comprises 1,1,2-trifluoroethane.
PCT/EP1993/003633 1992-12-23 1993-12-20 Mixtures useful for preparing a cellular polymeric material WO1994014882A1 (en)

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Cited By (1)

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US5626790A (en) * 1992-11-19 1997-05-06 E. I. Du Pont De Nemours And Company Refrigerant compositions including 1,1,2-trifluoroethane and hexafluoropropane

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EP0398148A2 (en) * 1989-05-10 1990-11-22 The Dow Chemical Company Preparation of urethane and isocyanurate foams in the presence of a low boiling point blowing agents
US4997706A (en) * 1990-02-09 1991-03-05 The Dow Chemical Company Foaming system for closed-cell rigid polymer foam
EP0427533A2 (en) * 1989-11-08 1991-05-15 The Dow Chemical Company Insulating alkenyl aromatic polymer foam
US5147896A (en) * 1991-05-20 1992-09-15 E. I. Du Pont De Nemours And Company Foam blowing agent composition and process for producing foams

Patent Citations (4)

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Publication number Priority date Publication date Assignee Title
EP0398148A2 (en) * 1989-05-10 1990-11-22 The Dow Chemical Company Preparation of urethane and isocyanurate foams in the presence of a low boiling point blowing agents
EP0427533A2 (en) * 1989-11-08 1991-05-15 The Dow Chemical Company Insulating alkenyl aromatic polymer foam
US4997706A (en) * 1990-02-09 1991-03-05 The Dow Chemical Company Foaming system for closed-cell rigid polymer foam
US5147896A (en) * 1991-05-20 1992-09-15 E. I. Du Pont De Nemours And Company Foam blowing agent composition and process for producing foams

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5626790A (en) * 1992-11-19 1997-05-06 E. I. Du Pont De Nemours And Company Refrigerant compositions including 1,1,2-trifluoroethane and hexafluoropropane

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