Compositions – Vaporization – or expansion – refrigeration or heat or energy... – With lubricants – or warning – stabilizing or anti-corrosion...
Reexamination Certificate
2000-01-10
2002-08-20
Einsmann, Margaret (Department: 1751)
Compositions
Vaporization, or expansion, refrigeration or heat or energy...
With lubricants, or warning, stabilizing or anti-corrosion...
C508S485000, C508S590000
Reexamination Certificate
active
06436309
ABSTRACT:
This application is the national phase under 35 U.S.C. §371 of PCT International Application No. PCT/FI98/003 13 which has an International filing date of Apr. 8, 1998 which designated the United States of America.
The present invention concerns a refrigerant composition according to the preamble of claim
1
. A composition of this kind generally contains a non-chlorinated hydrofluorocarbon based refrigerant composition together with a polyol ester based lubricant mixed therewith.
The invention also concerns complex esters according to claim
12
and lubricants containing these esters.
Lately, as a result of development in many fields of application, the evolution of polyolester type lubricants has been rapid. These products can be used as such or mixed with another base oil, such as a hydrocarbon, in engine oils for automotives, in aeroplane and gas turbine oils, as biodegradable hydraulic oils, as metal working oils and as compressor oils. These products are used in particular together with fluorinated refrigerants as a soluble lubricant component in refrigeration compressors due to their advantageous solubility properties, good technical stability and good cold properties.
The use of neopentylglycol and pentaerythritol esters together with refrigerants has been generally suggested. Although these known esters in principle exhibit good lubricant properties, their solubility in non-chlorinated hydrofluorocarbons is often only fair. For this reason they do not work well enough in refrigerant compositions containing fluorinated hydrocarbons.
It is an object of the present invention to eliminate the problems of the prior art and to provide polyol and complex esters of a novel kind which can be used in particular together with fluorinated refrigerant liquids as lubricants. It is another object of the invention to provide novel esters which are generally suited to the use as base oils of lubricants.
The present invention is based on the finding that esters of2-butyl-2-ethyl-1,3-propanediol have good lubricant properties in particular due to their chemical form. These esters exhibit the neopentyl structure typical for lubricants; the substitution of the carbon in position 2 is, however, asymmetric, i.e. the substituents are different, and because of this these esters have properties which differ from the usual properties. The esters of BEPD are hydrolytically very stable. They have good lubricant properties, they are also easily or very easily dissolved in fluorinated refrigerants and therefore suitable for use as lubricants in apparatuses employing such refrigerants. The lubricant used comprises in particular a polyol or complex ester prepared from BEPD (2-butyl-2-ethyl-1,3-propanediol) as such or from a mixture of BEPD and another polyol together with a monobasic carboxylic acid or an anhydride thereof (polyol esters) or with a mixture of a monobasic or dibasic carboxylic acids (complex esters).
More specifically, the refrigerant composition according to the present invention is mainly characterized by what is stated in the characterizing part of claim
1
.
Complex esters of BEPD are novel and useful as base oils of lubricant oils. The novel esters are characterized by what is stated in the characterizing part of claim
12
.
The present invention provides considerable advantages. The esters of BEPD have good lubricant properties and good solubility in HFC compounds used as refrigerants. The raw materials of said oils can be produced by the economically advantageous oxo-process (hydroformulation). The properties of the oils can easily be modified depending on the application by varying the ratio of the polyols of the ester (the amount of BEPD can be 100 to 5 mol-% of the total amount of polyol), the esterifying carboxylic acid and/or the ratio between the esterifying carboxylic acids. By using branched acids the solubility can be improved and by using dibasic acids the viscosity can be raised.
In the following, the invention will be examined with the aid of a detailed description and using a number of working examples.
The present esters comprise polyol or complex esters of 2-butyl-2-ethyl-1,3-propanediol. “Polyol ester” means i.a. esters having a carboxylic group comprising an monobasic acid or an anhydride thereof. For the purpose of the present invention, the term “polyol ester” comprises generally also “complex esters” which are esters in which at least a part of the esterifying acids are dibasic. Usually both carboxylic groups of these acids react with an alcohol and yield oligomeric ester compounds, which contain at least two alcohol residues and one carboxylic acid residue. Complex esters also include esters having the carboxylic acid residue formed by a hydroxy acid containing both a hydroxyl group and a carboxylic group. The carboxylic group reacts with the polyol, whereas the hydroxyl group reacts with the carboxylic group of another carboxylic acid.
“Polyol” stands for a compound with at least two hydroxy groups. According to the present invention BEPD can be esterified alone or together with another polyol. These polyols are, e.g., NPG (neopentylglycol), HPHP (hydroxypivalyl hydroxypivalate), ETHD (2-ethyl-1,3-hexanediol), TMP (trimethylol propane), TME (trimethylol ethane), PE (pentaerythnitol), TMPD (2,2,4-trimethyl-pentanediol) and CHDM (1,4-dimetylol-cyclohexane).
Preferably the polyol ester mixtures are formed by mixing the polyols together and by esterifying the thus formed mixture in situ.
According to a first preferred embodiment of the invention, a refrigerant liquid composition is provided, comprising a polyol ester which completely or almost completely (95 mol-%, or even 100%) consists of an ester of BEPD.
According to another preferred embodiment of the present invention, a refrigerant liquid composition is provided, comprising in addition to a polyol ester of BEPD an ester of NPG, HPHP, ETHD, TMP, TME, PE, BEPD or TMPD at any ratio, typically 5:95 to 100:0. Preferably BEPD forms the main part of the polyol residue of the ester mixture, i.e. its molar amount is 50% -99.9%, usually 50-95%.
BEPD or a mixture of BEPD and some other polyol is esterifled with a linear or branched C
4
to C
18
carboxylic acid or an anhydride thereof. As specific examples of aliphatic, linear or branched, saturated or unsaturated C
4
-C
18
-carboxylic acids which can be used for preparing the ester, the following can be mentioned:
saturated, linear C
4
-C
18
-carboxylic acids: butanoic acid (butyric acid), pentanoic acid (valeric acid), hexanoic acid (caproic acid), heptanoic acid, octanoic acid (caprylic acid), decanoic acid (capric acid), dodecanoic acid (lauric acid) and hexadecanoic acid (palmitic acid) and mixtures thereof;
saturated, branched C
4
-C
18
-carboxylic acids: isobutanoic acid, 2ethylhexanoic acid, isononanoic acid and 3,5,5-trimethylhexanoic acid;
unsaturated, linear C
4
-C
18
-carboxylic acids: 3-butenoic acid (vinylacetic acid); and unsaturated, branched C
4
-C
18
-carboxylic acids.
In the mixed esters the ratios between the various linear and branched carboxylic acids can vary within large boundaries. Typically, the linear carboxylic acid(s) is (are) present in amounts of 1 to 100 mol-%, preferably about 10 to 90 mol-% of the amount of carboxylic acids. Correspondingly, the amount of branched carboxylic acids is 99 to 1 mol-%, preferably about 90 to 10 mol-%. In particular it is possible to prepare polyolesters, which contain 10 to 50 mol-% of at least one linear carboxylic acid and 90 to 50 mol-% of a branched carboxylic acid.
When polyol esters of BEPD are prepared it is preferred to select linear or branched acids containing 4 to 14 carbon atoms as esterifying carboxylic acid. Octanoic acid, 2-ethylhexanoic acid and lauric acid can be mentioned as examples.
Esterifing hydroxy acids are, e.g., hydroxypivalic acid (HPAA), lactic acid, citric acid and dimethylolpropionic acid (DMPA).
In addition to the afore-mentioned, the esterifying carboxylic acid used can comprise dibasic carboxylic acids, such as oxalic acid, malonic acid, dimethylmalonic acid, succinic
Ankner Kjell
Glad Essi
Koistinen Jari
Rahkola Håkan
Saranp{umlaut over (aa)} Virpi
Birch Stewart Kolasch & Birch, LLP.
Einsmann Margaret
Fortum Oil and Gas Oy
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