The present invention provides a composition comprising dichloromethane and additionally one or more hydrofluoroalkanes. These compositions are very useful as blowing agents, in cleaning or deposition of certain types of lubricants, as a dust off, freeze spray, or tire inflator.

BACKGROUND OF THE INVENTION
Foam blowing agent is a substance, which is capable of producing a cellular structure via a foaming process in a variety of materials that undergo hardening or phase transition, such as polymers & plastics. Different kind of foams have different applications e.g., Polyurethane foams are useful in refrigeration system, spray foam, rigid foam. Flexible foams are useful in mattresses, pillows and cushions.
Fluorocarbons have found widespread use in many commercial and industrial applications, including as aerosol propellants and as foam blowing agents. Owing to their high ozone depleting potential (ODP), chlorofluorocarbons ("CFCs") and hydrochlorofluorocarbons ("HCFCs") have increasingly being replaced by low to zero ozone depletion potential (ODP), compounds such as hydrofluoroalkanes.
PCT Pub. No. 1999035209 discloses an azeotrope-like composition comprising from about 80 to about 99.9 weight percent 1,1,1,3,3-pentafluoropropane (R245fa) and from about 0.1 to about 20 weight percent of a chlorinated ethylene such as methylene chloride.
There remains a need to develop efficient blowing agents that can be used for wide variety of applications. The present invention provides a composition comprising dichloromethane and hydrofluoroalkanes, which can be used for wide varieties of foam blowing applications.
The present invention provides a composition comprising dichloromethane and additionally one or more hydrofluoroalkanes.

OBJECT OF THE INVENTION
The main object of the present invention is to provide a composition comprising dichloromethane and additionally one or more hydrofluoroalkane for use as blowing agents or in cleaning or deposition of certain types of lubricants, as a dust off, freeze spray or tire inflator.

SUMMARY OF THE INVENTION
The present invention provides a composition comprising, 5% by weight to 95% by weight of dichloromethane; and 5% by weight to 95% by weight of one or more of hydrofluoroalkane.

DETAILED DESCRIPTION OF THE INVENTION
As used herein, the term “hydrofluoroalkane” refers to a component selected from a group consisting of difluoromethane (R-32), fluoroethane (R-161), difluoroethane (R-152a), trifluoroethane (R-143a), tetrafluoroethane (R-134a and R-134), pentafluoroethane (R-125), pentafluoropropane (R-245fa), hexafluoropropane (R-236ea and 236fa), heptafluoropropane (R-227ea), pentafluorobutane (R-365mfc), and hexafluorobutane (R-356).
As used herein, the non-azeotropic composition is a mixture of two or more substances that behaves as a simple mixture rather than a single substance. One way to characterize a non-azeotropic composition is that the vapor produced by partial evaporation or distillation of the liquid has a substantially different composition as the liquid from which it was evaporated or distilled, that is, the admixture distills/refluxes with substantial composition change.
As used herein, the term “near azeotrope” is intended in its broad sense to include both compositions that are strictly azeotropic and compositions that behave like azeotropic mixtures. From fundamental principles, the thermodynamic state of a fluid is defined by pressure, temperature, liquid composition, and vapor composition. An azeotropic mixture is a system of two or more components in which the liquid composition and vapor composition are equal at the state pressure and temperature. In practice, this means that the components of an azeotropic mixture are constant boiling and cannot be separated during a phase change.
In an aspect, the present invention provides a composition comprising 5% by weight to 95% by weight of dichloromethane; and 5% by weight to 95% by weight of one or more of hydrofluoroalkane.
In a preferred aspect, the present invention provides a composition comprising 5% by weight to 70% by weight of dichloromethane; and 30% by weight to 95% by weight of one or more of hydrofluoroalkane.
In another embodiment, the present invention provides a composition comprising 50% by weight to 70% by weight of dichloromethane; and 30% by weight to 50% by weight of one or more of hydrofluoroalkane.
In another embodiment, the present invention provides a composition comprising 60% by weight to 90% by weight of dichloromethane; and 10% by weight to 40% by weight of one or more of hydrofluoroalkane.
In another embodiment, the present invention provides a composition comprising 50% by weight to 70% by weight of dichloromethane; and 30% by weight to 50% by weight of R245fa.
In another embodiment, the present invention provides a composition comprising 55% by weight to 65% by weight of dichloromethane; and 35% by weight to 45% by weight of R245fa.
In another embodiment, the present invention provides a composition comprising 58% by weight to 62% by weight of dichloromethane; and 38% by weight to 42% by weight of R245fa.
In another embodiment, the present invention provides a composition comprising 20% by weight to 70% by weight of dichloromethane; 10% by weight to 70% by weight of R245fa; and 1% by weight to 20% by weight of one additional hydrofluoroalkane.
In another embodiment, the present invention provides a composition comprising 20% by weight to 70% by weight of dichloromethane; 10% by weight to 70% by weight of R245fa; and 1% by weight to 20% by weight of one additional component selected from a group consisting of R134a, R227ea, and R152a.
In another embodiment, the present invention provides a composition comprising 20% by weight to 70% by weight of dichloromethane; 10% by weight to 40% by weight of R245fa; and 5% by weight to 20% by weight of one additional component selected from a group consisting of R134a and R152a.
In another embodiment, the present invention provides a composition comprising 40% by weight to 65% by weight of dichloromethane; 15% by weight to 55% by weight of R245fa; and 2% by weight to 20% by weight of one additional component selected from a group consisting of R134a and R152a.
In another embodiment, the present invention provides composition comprising 42 to 46 % by weight of dichloromethane; 52 to 55 % by weight of R245fa and 1.5 to 3 % by weight of R134a.
In another embodiment, the present invention provides a composition comprising 70% by weight to 95% by weight of dichloromethane; and 5% by weight to 30% by weight of one or more of hydrofluoroalkane selected from a group consisting of R245fa, R134a and R152a.
In an embodiment, the present invention provides a composition comprising 70% by weight to 95% by weight of dichloromethane; and 5% by weight to 30% by weight of R245fa and one additional component selected from a group consisting of R134a and R152a.
In an embodiment, the present invention provides a composition comprising 85% by weight to 92% by weight of dichloromethane; and 8% by weight to 30% by weight of R245fa and one additional component selected from a group consisting of R134a and R152a.
In an embodiment, the present invention provides a composition comprising 80% by weight to 90% by weight of dichloromethane; and 12% by weight to 17% by weight of R152a.
The present invention provides composition comprising 20% by weight to 50% by weight of dichloromethane; and 50% by weight to 80% by weight of one or more of hydrofluoroalkane.
In an embodiment, the present invention provides composition comprising 25% by weight to 48% by weight of dichloromethane; 48% by weight to 70% by weight of R245fa and 2% by weight to 6% by weight of R134a.
In another embodiment, the present invention provides composition comprising 25 to 30% by weight of dichloromethane; 65 to 70% by weight of R245fa and 4 to 6% by weight of R134a.
In another embodiment, the present invention provides composition comprising 31 to 37 % by weight of dichloromethane; 55 to 60 % by weight of R245fa and 4 to 6 % by weight of R134a.
In another embodiment, the present invention provides composition comprising 40 to 44 % by weight of dichloromethane; 52 to 55 % by weight of R245fa and 2 to 5 % by weight of R134a.
In another embodiment, the present invention provides composition comprising 45 to 49 % by weight of dichloromethane; 48 to 51 % by weight of R245fa and 2 to 4 % by weight of R134a.
Dichloromethane, R227ea, R152a and R245fa are commercially available or may be prepared by methods known in the art.
R134a is commercially available or may be prepared by methods know in the art, such as by the hydrogenation of 1,1-dichloro-1 ,2,2,2-tetrafluoroethane (i.e., CCI2FCF3 or CFC-114a) to 1 ,1 ,1 ,2-tetrafluoroethane.
In another embodiment of the present invention, the compositions comprising dichloromethane and hydrofluoroalkenes are useful blowing agents in foams and cleaning agents.
In another embodiment, the blowing agent compositions of present invention are capable of producing a cellular structure via a foaming process in a variety of materials that undergo hardening or phase transition, such as polymers & plastics having different applications.
In another embodiment, the blowing agent compositions of the present invention are used for making rigid foams used in refrigeration and insulation products.
In another embodiment, the compositions of the present invention are used for making foams useful for insulation of commercial/residential buildings, insulated metal panels, and appliance insulation.
In another embodiment, the composition of the present invention finds widespread use in industry for solvent cleaning and solvents in aerosols for the degreasing and otherwise cleaning of solid surfaces, especially intricate parts and difficult to remove soils.
The chlorinated ethylene component such as dichloromethane has good solvent properties to enable the cleaning and dissolution of flux resin and oils.
In another embodiment, the compositions of the present invention are useful as aerosol solvent applications for cleaning or deposition of certain types of lubricants, as a dust off, freeze spray or tire inflator. The compositions of the present invention act to propel and convert user product such as paints, lubricants, fire extinguisher and electrical & instrumentation panel cleaning agents into aerosols.
The compositions of the present invention have comparative high gas thermal conductivity as compared to compositions such as HCFC-141b. These compositions are very compatible with base polyols. They are completely soluble in base polyol and do not have any adverse effects on base polyols.
These compositions also have zero ozone depletion potential (ODP) and very low global warming potential (GWP), therefore are very environment friendly. The compositions of the present invention are non-flammable.
In an embodiment, the present invention provides blowing agent compositions having zero ODP and having GWP of below 700.
In another embodiment, the blowing agent composition of the present invention provides foams having good dimensional stability at low as well as at higher temperatures. The dimensional stability of a foam is calculated as a percentage reduction at a low temperature range of 0 to 20°C and at higher temperature range of 60-80 °C. The dimensional stability of the blowing agent compositions of the present invention are close to the dimensional stability obtained in HCFC-141b.
In another embodiment, the blowing agent compositions of the present invention provides foams having good compressive strength of 165 to 190 kPa for a foam of density of 40 kg/m3, which is comparable to the compressive strength of foams produced using HCFC-141b. The compressive strength shows the capacity of the foam to withstand the compressive load.
In another embodiment, the blowing agent compositions of the present invention provides foams having good flexural strength, which is comparable to the flexural strength of foams produced using HCFC-141b. Flexural strength also called bending strength is a capacity of foam material to resist deformation under bending moment and is relative the density of the foam used. The flexural strength of the foams produced using the blowing agent of the present invention is in the range of 0.18 to 0.29 N/mm2 with density of 40 kg/m3.
In another embodiment, the blowing agent compositions of the present invention provides foams having thermal conductivity comparable to the thermal conductivity of foams produced using HCFC-141b. The thermal conductivity is relative to the density of the foam used and the foams produced using the blowing agent of the present invention is in the range of 0.024 to 0.02 W/m-K with density of 40 kg/m3.
In another embodiment, the blowing agent compositions of the present invention provides foams with heat distortion temperature of 160 to 175°C for a density of 40 kg/m3, which is comparable to heat distortion temperature of foams obtained using HCFC-141b.
In another embodiment, the blowing agent compositions of the present invention provides foams, wherein no considerable change in volume percentage was observed at standard temperature pressure.
The blowing agent compositions of the present invention are useful in that they provide sufficient plasticization to permit the production of low density insulating thermoplastic foams with improved k-factor.
In a preferred embodiment, the present invention provides blowing agent compositions comprising dichloromethane and hydrofluoroalkane, wherein the composition has a boiling point of more than 20°C, and have thermal conductivity, heat distortion temperature, flexural strength, dimensional stability, compressive strength and GWP comparable to HCFC-141b and have zero ODP.
In another preferred embodiment, the present invention provides blowing agent compositions comprising dichloromethane and hydrofluoroalkane, wherein the compositions are environment friendly substitute for HCFC-141b.
The blowing agent compositions of the present invention has boiling point more than 20°C, preferably between 20 to 30°C.
A foamable polymer composition can contain additional additives such as nucleating agents, cell-controlling agents, dyes, pigments, fillers, antioxidants, extrusion aids, stabilizing agents, antistatic agents, fire retardants, IR attenuating agents and thermally insulating additives. Nucleating agents include, among others, materials such as talc, calcium carbonate, sodium benzoate, and chemical blowing agents such azodicarbonamide or sodium bicarbonate and citric acid. IR attenuating agents and thermally insulating additives can include carbon black, graphite, silicon dioxide, metal flake or powder, among others. Flame retardants can include, among others, brominated materials such as hexabromocyclodecane and polybrominated biphenyl ether.
The compositions of the present invention may be non-azeotropic, near azeotropic or azeotropic.
The process for foam preparation processes may include batch, semi-batch, and continuous processes.
Compositions comprising dichloromethane are very useful as blowing agents. These compositions have also found widespread use in industry for solvent cleaning and solvents in aerosols for the degreasing and otherwise cleaning of solid surfaces, especially intricate parts and difficult to remove soils.
The compositions of the invention may also be useful in aerosol solvent applications of cleaning or deposition of certain types of lubricants, as a dust off, freeze spray or tire inflator.
The chlorinated ethylene component such as dichloromethane has good solvent properties to enable the cleaning and dissolution of flux resin and oils.
It is against this and other backgrounds, which shall be filed in a detailed manner in complete specifications, in due course, the present invention is brought out and explained in following non-limiting examples.
It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention and specific examples provided herein without departing from the spirit and scope of the invention. Thus, it is intended that the present invention cover the modifications and variations of this invention that come within the scope of any claims and their equivalents.
The details of various components as used in the present invention are described in the table below.

Table-1
Components Chemical name Chemical formula
R245fa 1,1,1,3,3-Pentafluoropropane CF3CH2CHF2
R134a 1,1,1,2-tetrafluoroethane CH2FCF3
R152a 1,1-difluoroethane CHF2CH3
R227ea 1,1,1,2,3,3,3-Heptafluoropropane CF3CHFCF3

The quantity of various components as used in the present invention are described in the table below.
Table-2
Compositions DCM (% by weight) 245fa (% by weight) 134a (% by weight) 152a (% by weight)
1 60 40
2 65 25 10
3 65 30 5
4 65 20 15
5 65 15 20
6 60 25 15
7 60 30 10
8 60 35 5
9 45 53 2
10 65 25 10
11 65 30 5
12 65 20 15
13 65 15 20
14 60 25 15
15 60 30 10
16 90 10
17 85 15
18 85 15
19 42.11 54.74 3.15
20 47.37 49.47 3.16
21 36.84 57.89 5.27
22 26.32 68.42 5.26

The various physical and environment properties of the compositions of the present invention and prior art composition HCFC-141b are tabulated below.
Table-3
Properties of HCFC-141b
Molecular weight 116.9
Boiling point (°C) 32.9
Liquid specific gravity at 25°C 1.233
Heat of vaporization at boiling point (kJ/mole) 25.8
Gas phase thermal conductivity (mW/mK) at 10 °C 8.8
Gas phase thermal conductivity (mW/mK) at 25°C 10
Vapour pressure (kg/cm2) at 10°C 0.46
Vapour pressure (kg/cm2) at 25°C 0.79
Flammable limits in air (vol%) 7.6-17.7
ODP (with CFC-11 =1) 0.1 1
GWP (with C02 = 1) 700

Table-4
Properties of compositions of present invention
Molecular weight 70-150
Boiling point (°C) 7-38
Liquid specific gravity at 25°C 1.1-1.35
Heat of vaporization at boiling point (kJ/mole) 25-28.2
Gas phase thermal conductivity (W/mK) at 10°C 7-9.2
Gas phase thermal conductivity (W/mK) at 25°C 9-12
Vapour pressure (kPa) at 10°C 0.4-1.5
Vapour pressure (kPa) at 25°C 0.8-2.5
Flammable limits in air (vol%) None
ODP 0
GWP Less than 700

Table-5
Properties Composition
1 2 3 4 5
Molecular weight 109.49 95.25 96.33 94.20 93.18
Boiling point (°C) 25.00 18 23 13 9
Liquid specific gravity at 25°C 1.34 1.320 1.329 1.312 1.304
Heat of vaporization at boiling point (kJ/mole) 27.94 27.757 27.817 27.693 27.558
Gas phase thermal conductivity (mW/mK) at 10°C 8.58 8.503 8.450 8.555 8.607
Gas phase thermal conductivity (mW/mK) at 25°C 9.71 9.336 9.294 9.377 9.417
Vapour pressure (kg/cm2) at 10°C 0.47 0.767 0.608 0.922 1.075
Vapour pressure (kg/cm2) at 25°C 1.01 1.325 1.079 1.566 1.802
ODP 0 0 0 0 0
GWP 348.6 350.35 328.25 372.45 394.55

Table-6
Properties Composition
6 7 8 9 10
Molecular weight 96.16 97.25 98.37 105.84 90.64
Boiling point (°C) 12 17 20.00 23 14
Liquid specific gravity at 25°C 1.314 1.323 1.33 1.343 1.273
Heat of vaporization at boiling point (kJ/mole) 27.642 27.701 27.89 27.528 28.035
Gas phase thermal conductivity (mW/mK) at 10 °C 8.857 8.691 8.64 9.196 8.728
Gas phase thermal conductivity (mW/mK) at 25°C 9.597 9.556 9.51 10.182 9.597
Vapour pressure (kg/cm2) at 10°C 0.954 0.795 0.63 0.609 0.876
Vapour pressure (kg/cm2) at 25°C 1.619 1.374 1.12 1.104 1.493
ODP 0 0 0 0 0
GWP 414.9 392.8 370.7 484.79 234.15

Table-7
Properties Composition
11 12 13 14 15
Molecular weight 93.91 87.60 84.74 89.28 92.45
Boiling point (°C) 21 9 5 8 13
Liquid specific gravity at 25°C 1.304 1.243 1.215 1.245 1.275
Heat of vaporization at boiling point (kJ/mole) 27.962 27.965 27.509 27.917 27.982
Gas phase thermal conductivity (mW/mK) at 10 °C 8.568 8.879 9.022 8.948 8.916
Gas phase thermal conductivity (mW/mK) at 25 9.430 9.754 9.902 9.974 9.817
Vapour pressure (kg/cm2) at 10°C 0.668 1.070 1.252 1.102 0.905
Vapour pressure (kg/cm2) at 25°C 1.172 1.793 2.074 1.847 1.543
ODP 0 0 0 0 0
GWP 312.6 198.15 162.15 240.6 276.6
Table-8
Properties Composition
16 17 18
Molecular weight 86.38 87.12 81.44
Boiling point (°C) 23 16 12
Liquid specific gravity at 25°C 1.309 1.303 1.235
Heat of vaporization at boiling point (kJ/mole) 28.079 27.982 28.240
Gas phase thermal conductivity (mW/mK) at 10°C 7.621 7.842 8.166
Gas phase thermal conductivity (mW/mK) at 25°C 8.303 8.543 8.921
Vapour pressure (kg/cm2) at 10°C 0.642 0.810 0.954
Vapour pressure (kg/cm2) at 25°C 1.109 1.373 1.597
ODP (with CFC-11 =1) 0 0 0
GWP (with C02 = 1) 138.1 202.65 28.35

Table-9
Compositions
Properties 19 20 21 22
Molecular weight 106.95 104.411 109.02 114.698
Boiling point (°C) 22 23 18 16
Vapour pressure (kg/cm²) at 10°C -0.58264 -0.60271 -0.55345 -0.49276
Vapour pressure (kg/cm²) at 25°C -0.18866 -0.22518 -0.13555 -0.02611
Vapour pressure (kg/cm²) at 50°C 1.01994 0.935276 1.14319 1.39366
Gas phase thermal conductivity (W/mK) at 10°C 9.32742 9.11281 9.56942 10.0249
Gas phase thermal conductivity (W/mK) at 25°C 10.3306 10.0787 10.6052 11.1398
Heat of vaporization at boiling point (kJ/mole) 274.9004 281.8314 268.8928 253.0646
Flash point (°C) Above 200 Above 200 Above 200 Above 200
Flammability of liquid Not Flammable Not Flammable Not Flammable Not Flammable
ODP 0 0 0 0
GWP 514.4842 469.8 568.4737 657.8421

EXAMPLE
The compositions of the present invention were prepared by adding different components in increasing order of vapour pressure and were analyzed using ASPEN.

WE CLAIM:

1.A composition comprising, 5% by weight to 95% by weight of dichloromethane; and 5% by weight to 95% by weight of one or more of hydrofluoroalkanes selected from a group consisting of R245fa, R134a, R152a and R227ea.
2. The composition as claimed in claim 1, wherein the composition comprising, 5% by weight to 70% by weight of dichloromethane; and 30% by weight to 95% by weight of one or more of hydrofluoroalkanes selected from a group consisting of R245fa, R134a, R152a and R227ea.
3. The compositions as claimed in claim 1, wherein the compositions are used as blowing agent, cleaning solvent and aerosols.
4. The compositions as claimed in claim 1, wherein the compositions are non-flammable, have zero ozone depletion potential and global warming potential of less than 700.
5. The blowing agent compositions as claimed in claim 1, wherein the compositions provide foams with good dimensional stability at low as well as at higher temperatures.
6. The blowing agent compositions as claimed in claim 1, wherein the compositions provide foams with compressive strength, comparable to the compressive strength of foams produced using HCFC-141b.
7. The blowing agent compositions as claimed in claim 1, wherein the compositions provide foams with flexural strength, comparable to the flexural strength of foams produced using HCFC-141b.
8. The blowing agent compositions as claimed in claim 1, wherein the compositions provide foams with thermal conductivity comparable to the thermal conductivity of foams produced using HCFC-141b.
9. The blowing agent compositions as claimed in claim 1, wherein the compositions provide foams with heat distortion temperature of 165°C to 180°C, which is comparable to heat distortion temperature of foams obtained using HCFC-141b.
10. The blowing agent compositions as claimed in claim 1, wherein the compositions have boiling point in a range of 20 to 30°C.