MXPA99008123A - Azeotropic or pseudo-azeotropic compositions and use of these compositions - Google Patents

Abstract

The invention concerns 1,1,1,3,3-pentafluorobutane which forms azeotropic or pseudo-azeotropic compositions with alkanes having 5 or 6 carbon atoms. These compositions are used in particular as foaming agents in polymeric cell-closed foams.

Description

cyclopentane or even 5% hexane. Murphy and his collaborators (International CFC and Halon Alternatives Conference, Washington DC, 1993, pages 346-355) have described the use of binary mixtures of cyclopentane and HFC-365mfc containing at least 54% by weight of cyclopentane as an agent of expansion for polyurethane foams. It has however been noted that HFC-3.65mfc. and the aforementioned mixtures run the risk, in certain cases and in certain circumstances, of condensing within the cells of the puma, implying, if necessary, deterioration. of its thermal conductivity and eventually of its mechanical properties. There remains a need to find compositions of expanded agents for polymeric cellular foams, which are devoid of harmful effects to the environment, which have a boiling point near the boiling point of CFll or 1,1-dichloro-l. -fluoroethane (HCFC-141b) and having physical properties that allow to form polymeric cellular foams of low thermal conductivity within a wide range of temperatures, particularly foams with closed cells and homogeneous size.

OBJECTS AND ADVANTAGES OF THE INVENTION One of the objects of the present invention P1515 / 99 X weight of 1, 1, 1, 3, 3-pentafluorobutane and by about 34% by weight of n-pentane, constitutes a true azeotrope, whose boiling point is about 27.4 ° C. This composition is very particularly preferred. The 1,1,1,3,3-pentafluorobutane and the cyclopentane form an azeotrope or a binary pseudo-azeotrope when their mixture contains approximately 16 to 46% by weight of cyclopentane.

Binary compositions containing about 18.5 to 39% by weight of cyclopentane are preferred. Particularly preferred are binary compositions containing approximately 20 to 35% by weight of cyclopentane. Under one At a pressure of 101.1 kPa, the binary composition, consisting essentially of about 78.5% by weight of 1, 1, 1, 3, 3-pentafluorobutane and about 21.5% by weight of cyclopentane, constitutes a true azeotrope, whose point of boiling is approximately 32.2 ° C. This composition is very particularly preferred. 1, 1, 1, 3, 3 -pentafluorobutane and the _? * isopentane form an azeotrope or a binary pseudo-azeotrope when its mixture contains about 31 to 75% by weight of isopentane. Binary compositions containing approximately 39 to 70% by weight of isopentane are preferred. Binary compositions are particularly preferred X P1S15 / 99MX of the 3- or 3- of me C.

I do not know 9% as you give in, or you the to in Un en ro This is a molten polymer blend that is to be expanded into an extruder. The decomposition * I obtained at the exit of the extruder leads to the expansion of the polymer mixture with formation of a foam constituted by cells filled with the expansion agent. Polystyrene foams are usually obtained by this process. Other -TO. The process, typically used to manufacture polyurethane or polyisocyanurate foams, is to react an isocyanate with an appropriate amount of a polyol or a mixture of polyols, in the presence of a blowing agent consisting of a volatile liquid, which is vaporized by the heat evolved by the reaction between the isocyanate and the polyol The compositions according to the invention are particularly recommended for the expansion of polyurethane or polyisocyanurate foams, very particularly for making rigid foams. In this case, it is generally used from 1 to 40, typically from 15 to 35 parts by weight of the polyol The invention also concerns expansion agents for polymeric cellular foams, which are characterized in that they contain a composition azeotropic or pseudo-azeotropic according to the invention. The blowing agents containing a composition according to the invention, consisting of • 1, 1, 1, 3, 3 -pentafluorobutane and cyclopentane are -A P1515 / 99MX H particularly adapted for the preparation of polyurethane or polyisocyanurate foams. In a variant according to the invention, the blowing agents also contain n-butane or isobutane, typically in a proportion of 2 to 20% by weight, preferably 5 to 15% by weight. The blowing agents for polymeric cellular foams can also contain a stabilizer for the azeotropic composition or pseudo-azeotropic according to the invention, for example, -r nitromethane or alpha-methylstyrene. The azeotropic or pseudo-azeopropy compositions according to the invention can be used in i f 'premixes for polyurethane foams or polyisocyanurate. Such premixes contain at least one polyol, an azeotropic or pseudo-azeotrope composition according to the invention and various additives commonly used to prepare polyurethane and polyurethane foams. polyisocyanurate, for example, especially water, -i catalysts, surfactants, antioxidants, flame retardants and / or pigments. Premixes containing the azeotropic or pseudo-azeotropic compositions according to the invention also form part of the present invention. The invention also concerns the use of the azeotropic or pseudo-azeotropic compositions described above, in the capacity of P1515 / 99 X? His composition. These measurements have been made for mixtures containing 1, 1, 1, 3, 3-pentafluorobutane and increasing amounts of n-pentane (Example 1), cyclopentane (Example 2), isopentane (Example 3) or n-hexane Example 4). The pressure at which the measurements have been made is mentioned. The evolution of the boiling temperature of the different compositions, as a function of their hydrocarbon content, expressed in% by weight, is presented in Table I. r S P1515 / 99MX F i. TABLE I S Item I P1515 / 99MX EXAMPLES 5-8 i. Polyurethane foams have been prepared starting from the same formulation, but using as an expanding agent, either HFC-365mfc (Example 5), 5-cyclopentane (Example 6), a composition of HFC-7 365mfc and cyclopentane constituted by 72 parts in - "weight of HFC-365mfc and 28 parts by weight of cyclopentane (Example 7), and a composition of HFC-365mfc and n-pentane constituted by 58.4 part by weight of HFC-.365mfc and 41.6 parts by weight of n-pentane (Example 8). Then, the thermal conductivity (Lambda) of these foams at different temperatures was measured. The variations of v thermal conductivity are presented in Table II. __ »15 The thermal conductivity, measured at 24 ° C, of a foam obtained with HFC-365mfc has been taken as a reference. The variations are expressed in so many - percent in relation to this reference. A positive variation corresponds to an increase in ? i 20 conductivity, meaning a decrease in power -. foam insulation. .and* * P1515 / 99 X cyclopentane presents at low temperature a IT thermal conductivity lower than that of a foam Compared with HFC-365mfc, in the absence of "ir-cyclopentane -4 Similar results have been obtained with the azeotropic composition of HFC-365mfc and n-pentane.

P1515 / 99MX

Claims (5)

1. NOVELTY OF THE INVENTION Having described the present invention, it is considered as a novelty and, therefore, the content of the following is claimed as property. 5 CLAIMS; 1. Composition consisting essentially of 1, 1, 1, 3, 3-pentafluorobutane and an alkane containing 5 or 6 carbon atoms, characterized in that it is azeotropic or pseudo-azeotropic.
2. 2. The composition according to claim 1, wherein the alkane containing 5 or 6 carbon atoms is selected from n-pentane, cyclopentane, isopentane and n-hexane.
3. 3. Composition according to claim 2, Which contains about 24 to 60% by weight of n-pentane or about 16 to 46% by weight of cyclopentane or about 31 to 75% by weight of isopentane or about 6 to 29% by weight of n-hexane.
4. 4. The composition according to claim 3, which contains about 30 to 53% by weight of n-pentane or about 18.5 to 39% by weight of cyclopentane or about 39 to 70% by weight of isopentane t or about 9.5 to 24% by weight of n-25 hexane.
5. 5. The composition according to claim 2, which contains about 32 to 47% by weight of "n-pentane or about 20 to 35% by weight of P1515 / 99 X polymeric cellular foams. 11. Use according to claim 10,? characterized in that the polymeric cellular foam is a polyurethane or polyisocyanurate foam. 12. Expansion agent for foams # 1, polymeric cells, characterized in that it comprises a azeotropic or pseudo-azeotropic com- position > . 10 according to any of claims 1 to 9. 13. Premix for polyurethane foam, _. characterized in that it comprises an azeotropic or pseudo-azeotropic composition according to any of claims 1 to 9, at least one polyol and V 15 optionally various customary additives. compositions according to claims 1 to 9 as cooling fluids, as solvents, as desiccating agents or as solid surface degreasing agents. r J