JPH08505159A - Compressor lubricant that can withstand the overuse of polyol esters - Google Patents

Abstract

  (57) [Summary] A refrigeration compressor, especially chlorine-free, provided by mixing a hindered polyol, most preferably an ester of pentaerythritol, with a carboxylic acid mixture containing some isopentanoic acid together with at least 13% of a dibasic acid such as adipic acid. Hydrofluorocarbon Refrigerant High-performance abuse-resistant lubricant for compressors using fluid working substances.

Description

Detailed Description of the Invention          Compressor lubricant that can withstand the overuse of polyol esters   Reference to related applications   This application was filed on June 3, 1992 and is designated as the United States of America at the same time. Continuation international application Partial continuation application of PCT / US92 / 04438. All that The disclosures are incorporated herein by reference. However, it is contrary to what is explicitly stated in this specification. Except.   Background of the invention   Field of the invention   The present invention may also serve as a complete lubricant; lubricant base material; High-pressure resistance and / or wear resistance, corrosion protection with lubricant-providing lubricant base material Compounded lubricant containing at least one additive for the purpose of improving etc .; original heat transfer flow Coolant fluid working substances comprising a lubricant according to the invention with the body; and these materials Regarding how to use. Lubricants and lubricant base materials generally contain almost all Suitable for use with halocarbon coolants, especially pentafluoroethane, 1, 1-difluoroethane, 1,1,1-trifluoroethane, and tetrafluor Substantially chlorine such as loethane, especially 1,1,1,2-tetrafluoroethane Suitable for use with free, fluoro-containing organic refrigeration heat transfer fluids. these Lubricant and base materials combined with our heat transfer fluid cycle Lubrication compressors requiring ISO grades of about 320 to about 1000 for Especially suitable for sir.   Description of related technology   Chlorine-free heat transfer fluids are suitable for use in coolant systems. Because it Even if it leaks to the atmosphere, the damage to the environment is Currently most commonly used chlorofluorocarbons such as dichlorodifluoromethane It is smaller than carbon heat transfer fluid. However, lack of commercially suitable lubricants Prevailing commercial use of chlorine-free coolant heat transfer fluids is prohibited Has been done. This is one of the most desirable fluid working substances, "coolant 134a". Or, it is commonly used in the art as "R134a" 1,1, This is especially true for 1,2-tetrafluoroethane. Other fluoro-substituted eta Is also a desirable fluid actuating material.   Hindered polyol ester, which has at least 5 carbon atoms, 2-OH Containing a group and directly bound to a carbon atom having an OH group Defined for this purpose as an organic molecule that has no hydrogen atoms Most types that use Luorocarbon coolant, especially chlorine-free Already recognized in the art as a high quality lubricant base material for It The following patents and published patent applications list polyols useful as coolant lubricants. It shows a number of general classes of Ter and specific examples: US 4,851,14 4; UK2 216 541; US 5,021,179; US 5,096,60. 6; WO90 / 12849 (lubrizol); EP0 406 479 (joint stone) Oil); EP 0 430 657 (Asahi Denka Co., Ltd.); EP 0 435 25 3 (Nippon Petroleum); EP 0 445 610 and 0445611 (Hoechst A) G); EP 0449 406; EP 0 458 584 (Unichemema Chem BV); and EP 0 485979 (Hitachi).   Description of the invention   Except for the claims and examples, or unless explicitly stated otherwise, the amount of substance or Indicates the reaction conditions and / or uses Understood to be modified by the term "about" in defining the range It should be. However, within the bounds corresponding to the exact amount stated Practice of the invention is preferred.   More specifically, the ester mixture according to the present invention has a viscosity of 1300 centist at 40 ° C. Arks or less, preferably 1100 centistokes or less, more preferably 99 It should have a viscosity of 0 centistokes or less. The essence of the present invention The tellurium mixture at 40 ° C is at least 450 centistokes, preferably 600 centistokes. To have a viscosity of more than 810 centistokes. Should.   The selected polyol ester provides a high quality lubricant for this type of service. It was found to be offered.   (I) 2,2-dimethylol-1-butanol (“trimethylolpropane”) Is also known as "TMP" and is often abbreviated as "TMP" hereinafter); Propane (hereinafter often abbreviated as "DTMP"), the molecule of which is four It is a molecule having a roxy group and one ether bond, and is formally two TMs. One hydroxyl group from one TMP of P and the hydr of the other TMP molecule Removing the hydrogen atom of the roxy group to form water, the two residues of the first TMP molecule Obtained by linking with an ether bond; 2,2-dimethylol-1, 3-propanediol (also known as "pentaerythritol", , Often abbreviated as “PE”); and di-pentaerythritol (hereinafter “D”). Abbreviated as "PE"), the molecule has 6 hydroxyl groups and 1 ether. A molecule having a bond, formally a water molecule as described above for DTMP. It is obtained from two PE molecules by elimination of; tripentaerythritol (hereinafter, Often abbreviated as "TPE"), the molecule contains eight hydroxyl groups and two ether groups. It is a molecule having an ether bond, and is formally (for example, to DTMP and DPE). (For elimination of one water molecule) 2 PEs from 2 PEs as described above The molecule is desorbed and induced; tri-tri-methylolpropane (hereinafter often referred to as Abbreviated as "TTMP", the molecule consists of 5 hydroxyl groups and 2 ether linkages. Is a molecule with a combination of two water, formally as described above for TPE. Derived from three TMP molecules by elimination of the molecule; alcohol selected from A mixture of molecules, (ii) linear and branched mono-salts having 4 to 12 carbon atoms Reacting with a mixture of acid molecules selected from the group of all-carboxylic acids of bases and two bases Let The ester or mixture of esters made is particularly effective. But selected For the alcohol content and the acyl group of the ester mixture (a) It is preferable that at least 15% of the silyl groups, or more in the following order, be used. At least 27, 36, 45, 51, 56 or 62% of the total amount is 2-methylbutane Noyl or 3-methylbutanoyl group (hereinafter, these are combined and referred to as “iC_FiveAcid Abbreviated as "(or) acyl group"), (b) branched and greater than 6 Acyl groups in the mixture having less than 5, preferably not more than 5, carbon atoms An acyl group in the mixture having 8 or more carbon atoms and being unbranched with respect to% of % Ratio not greater than 1.56, preferably not greater than 1.21, more Preferably not greater than 1.00; (c) may or may not be branched The percentage of acyl groups in the ester mixture having at least 9 carbon atoms is 81. Not greater than, preferably not greater than 67, more preferably greater than 49 No; (d) no more than 2% of the acyl groups in the ester mixture, preferably No more than 1 and more preferably no more than 0.4% (E) an acid in the ester mixture, which is derived from an acid molecule having a ruboxyl group. It is preferable that at least 13.8% of all the groups be present, or in the order given below, 15.3, 16.2, 17.0, 17.6, 18.2, 18.9% are dibasic acids Yes; at least 82% of monobasic acyl groups in the acid mixture, or more in the following order More preferred, but at least 85, 89, 93, 96 or 99% Subject to the restriction that the metric has 5 or 6, more preferably 5 carbon atoms. In all these percentages, the acyl group is related to the valence of the acyl group. It counts as one base. For example, each molecule of adipic acid is a complete ester When converted, it produces a single, two-base, acyl group.   (Of course, all types of esters described herein as part of the present invention Reacts with acid derivatives such as acid anhydrides, acyl chlorides and acid esters to the acid itself. Alternatively, the ester product according to the present invention may have a lower content than the desired alcohol. The same ester or mixture of esters by reacting with a small amount of alcohol It is possible to obtain. Acids are usually preferred from the economical point of view, and Is specified in. However, the ester defined here in reaction with an acid is By reacting an alcohol with the corresponding acid derivative, or even by other reactions It should be understood that they are equally affordable. Just one The key feature is that of the acyl and alcohol moieties in the final ester mixture formed. It is a mixture.   Preferably, it can be reacted to prepare the ester mixture of the invention. 60% of the hydroxyl groups in the alcohol mixture, or Preferred but total amount of at least 75, 85, 90, 95 or 98% Is a PE, DPE and / or TPE molecule. Separately from the present invention Hydroxy in a mixture of alcohols that can be reacted to prepare the tellurium. At least 60% of the silyl groups or more in the following order are more preferable, but less At least 75, 85, 90, 95 or 98% of the total amount being PE molecules It Alternatively, it can be reacted with an alcohol to prepare the ester of the invention. In the acid mixture, the larger the number in the following order, the more preferable. Of at least 60, 75, 85, 90, 95, or 98% of the monobasic acid molecules of It is composed of molecules having 10 carbon atoms, and the larger the number in the following order, the better. However, at least 60,75,85,90,95 of dibasic acid molecules in the acid mixture Or 98% molecules having only 10 carbon atoms, preferably 5-7 carbon atoms Consists of. Most preferably at least 60,75 of monobasic acid molecules in the acid mixture, Total amount of 85, 90, 95, or 98% (in this order, the higher the more preferable) is 5 Or it consists of a molecule with 9 carbon atoms.   These choices for the acyl and alcohol moieties in the esters of the present invention are Based on empirically determined generalizations. To achieve the desired range of viscosities , Of dibasic acids and alcohols with at least 4 hydroxyl groups It is preferable to have a part. Commercially available hinders that meet this criteria Among alcohols, PE is less expensive than DTMP and Le There is no bond. The ether bond increases the hygroscopicity of the ester formed, which Can promote undesired corrosion of metal surfaces lubricated by .   When the number of carbon atoms per molecule is 9 or more, even branching is suitable by itself Is not sufficient to produce good solubility, and the upper limit for such acid moieties is independent. Then requested. I-C, which is generally particularly beneficial_FiveThe minimum amount of acid is dibasic acid or 8 or more. Solubilizes the ester moiety in a mixture containing a dibasic acid with the above carbon atom Identified to help.   For performance and economic reasons, a monobasic acid of 5 carbon atoms and 6 carbon atoms It has been found that dibasic acids are the most preferred ingredients.   Only the desired alcohols and acids are explicitly specified, and commercial and In most cases, some amount of impurities normally present in industrial grade products is It should be understood that they can be tolerated. For example, "commercial "Pentaerythritol" means di-pentaerythritol in an amount of 10 to 15 mol%. In general, pure pentaerythritol contains only about 85-90 mol%. Commercial pentaerythritol is often used as a lubricant of the present invention. It is satisfactory for use in the production of Tell. However, in general Hydroxyl groups in alcohol mixtures as specified in or herein 25% or less of any of the carboxyl groups in the acid mixture, or in the following order: The more preferable it is, the more preferable it is 21, 17, 12, 8, 5, 3, 2, 1, 0.5. Or less than 0.2% is clearly specified for each type of lubricant base stock It is preferable to be a part of a molecule other than the molecule. Special features specified here Percentage of certain chemical molecules or moieties, such as the carboxyls mentioned above And the percentage of hydroxyl groups etc. is understood as a percentage of the number Avogadro for each specific chemical moiety that should be and is considered the only chemical equivalent Mathematically the same as the chemical equivalent percentage of a number.   Each acid and alcohol mixture reacted to produce the lubricant ester of the present invention. The above description for compounds is the acid or alcohol that actually reacts to form the ester. For the purpose of the reaction. Be sure that the mixture of rucor has the same composition as the mixture that actually reacts. I do not suggest it. In fact, the reaction between the alcohol and the acid used is initially If the amount of acid loaded in the reaction mixture is greater than or equal to the equivalent of alcohol that reacts with the acid, It has been found that a 10-25% excess supply progresses more effectively . (Equivalent of acid is herein defined as the amount containing 1 gram equivalent of carboxyl groups. It is defined for the purpose, while the equivalent weight of alcohol is 1 group of hydroxyl groups. It is the amount containing the lamb equivalent). The composition of the mixture of acids that actually reacts depends on the product It can be determined by analysis of the acyl group content of the steal mixture.   Most or all esters and ester mixtures are preferred according to the invention. To be new, the reacting acid is better than the reacting alcohol and ester. Bring to low boiling point. Once this condition is achieved, most preferably at low pressures of 1-5 Torr It is preferred to remove excess acid remaining at the end of the esterification reaction by distillation. New   After such vacuum distillation, the product is a lubricant or lubricant base according to the invention. It is often ready for use as a material. I want to purify the product further Then, the content of free acid in the purified product after the first vacuum distillation was determined by the method of US Pat. By treating with an epoxy ester as taught in US Pat. No. 5,754. Or lime, alkali metal hydroxide or alkali metal carbonate It may be further reduced by neutralizing with an alkaline material. Epoxy aesthetic Excess epoxy ester under very low pressure for the second time Although it may be removed by distillation at room temperature, the reaction product between the epoxy ester and residual acid is It is harmless if left in the product. When using neutralization with alkali as a purification method, Prior to using the product as a lubricant and / or base material according to the invention, water Can be washed with unreacted excess alkali and excess alkali-neutralized fat. Highly preferred for removing small amounts of soap formed from fatty acids.   Depending on the conditions of use, esters such as those described here are perfect lubricants. As a functioning to your satisfaction. However, it is usually a complete lubricant, resistant to oxidation Property and heat stability improver, corrosion inhibitor, metal deactivator, lubricity additive, viscosity index improver, Pour point and / or floc point depressants, detergents, dispersants, defoamers, antiwear agents, And other substances that are indicated in the art as additives such as extreme pressure resistant additives. Is preferred. Many additives are multifunctional. Anti-wear and extreme pressure resistance, for example Some additives have both properties, while others are both metal deactivators and corrosion inhibitors. Some work. Cumulative of all additives, the amount being the total mixed lubricant formulation It is preferred that it does not exceed 8% by weight, more preferably 5% by weight.   The effective amount of said additives is generally not 0.01 with respect to the antioxidant component. 5%, 0.01 to 5% for corrosion inhibitors, and metal deactivator components 0.001 to 0.5%, 0.5 to 5% for active additives, viscosity index 0.01 for each component of the improver, pour point and / or floe point depressant. 2% of chair, 0.1 to 5% for each ingredient of detergent and dispersant, antifoaming agent 0.001 to 0.1%, and each component of antiwear agent and extreme pressure resistant agent Is in the range of 0.1 to 2%. All these percentages are % By weight and based on the total lubricant composition. It is more than the stated amount of additives. However, even the following amounts may be more suitable for special environments, and Single species or mixtures thereof may be used for each type of You should understand that.   Examples of suitable oxidation and thermal stability improvers include diphenyl-, dinaphth Cyl- and phenylnaphthyl-amines can be mentioned, The futyl group may be substituted, for example, N, N'-diphenylphenylene diene Amine, p-octyldiphenylamine, p, p-dioctyldiphenylamine , N-phenyl-1-naphthylamine, N-phenyl-2-naphthylamine, N -(P-dodecyl) -phenyl-2-naphthylamine, di-1-naphthylamine And di-2-naphthylamine; phenothiazines such as N-alkylphenothiazines Imino (bisbenzyl); and 6- (t-butyl) phenol, 2,6- The -(T-Butyl) phenol, 4-methyl-2,6-di- (t-butyl) pheno , 4,4'-methylenebis (2,6-di {t-butyl} phenol, etc. Examples thereof include dardphenol.   Examples of suitable cuprous metal quenchers include imidazole and benzamidazole. , 2-mercaptobenzthiazole, 2,5-dimercaptothiadiazole, sa Lysiridine-propylenediamine, pyrazole, benzotriazole, toltri Azole, 2-methylbenzamidazole, 3,5-dimethylpyrazole, and And methylenebisbenzotriazole. Benzotriazole Derivatives are preferred. Other more common metal deactivators and / or corrosion inhibitors Examples include organic acids and their esters, metal salts and acid anhydrides such as N- Oleyl-sarcosine, sorbitan monooleate, lead naphthaleneate, dodeceni L-succinic acid and its partial esters and amides, and 4-nonylphenoxy Acetic acid; primary, secondary and tertiary aliphatic and cycloaliphatic amines and organic and inorganic acids Amine salts, eg oil-soluble alkyl ammonium carboxylates; heterocycles Nitrogen-containing compounds such as thiadiazoles, substituted imidazolines, and oxanes Zolines; quinolines, quinones and anthraquinones; propyl gallate; Barium dinonylnaphthalene sulfonate; alkenyl succinic acid anhydride or acid And amide derivatives of dithiocarbamates, dithiophosphates Includes amine salts of alkyl acid phosphates and their derivatives Is.   Examples of suitable slip additives are long-chain derivatives of fatty acids and natural oils, such as esters. , Amines, amides, imidazolines, and borates.   Examples of suitable viscosity index improvers are polymethacrylate, vinylpyrrolidone and metac Copolymers with relates, polybutene, and styrene-acrylate polymers Is included.   Examples of suitable pour point and / or Flock point depressants are methacrylate-ethyi. Polymethacrylates such as len-vinyl acetate terpolymer, alkylated naphth Talen derivatives; and Friedelck of urea with naphthalene or phenols It includes the products of raft-catalyzed condensation.   Examples of suitable detergents and / or dispersants are polybutenyl succinamide; polybu Tenyl phosphoric acid derivatives; long-chain alkyl-substituted aromatic sulfuric acids and their salts; Alkyl sulfides, alkylphenols, and alkylphenols and aldehi It includes a metal salt of a condensation product with a salt.   Examples of suitable defoamers include silicone polymers and several acrylates Things.   Examples of suitable antiwear and extreme pressure resistant additives are sulfides such as octyl tarta sulfide. Fatty acids and fatty acid esters; sulfurized terpenes; sulfurized olefins; organic polysulfates I.e. amine salt of monohexyl phosphate, dinonylnaphthalene sulfonate Amine salt, triphenyl phosphate, trinaphthyl phosphate, diamine Phenylcresyl and dicresyl phenyl phosphate, naphthyl dipheni Amine phosphates such as ruphosphate and triphenylphosphorothionate , Alkyl acid phosphate, dialkyl phosphate, amine dithiofate Phosphates, trialkyl and triarylphosphorothionates, trialkyls And organics containing triarylphosphines and dialkylphosphites Phosphorus derivatives; Antimony dialkyldithiocarbamates and other dithiocarbamers G; chlorinated and / or fluorinated hydrocarbons, xanthate esters, etc. Is included.   Useful for fluorocarbon coolant fluid working materials under certain operating conditions Polyethylene, a key ingredient of most conventional lubricant basestocks that is taught to The presence in a polyether polyol type lubricant does not provide optimum stability, And / or is believed to be improperly miscible with the most useful lubricant additives It Therefore, in one embodiment of the present invention, the lubricant base stock and lubricant It is preferred that there is substantially no polyether polyol such as. "Substantially free" means that the composition comprises only about 10% by weight of the material. %, Preferably only about 2.6% by weight, more preferably about 1.2% by weight Meaning that it only contains degrees.   One major embodiment of the present invention is the use of a suitable heat transfer fluid such as a fluorocarbon and the like. A coolant fluid working substance comprising both of the lubricants of the invention. Preferably coolant fluid The working substance and the lubricant have chemical properties and the operation of the cooling system in which the fluid working substance is used. Uniform fluid working substance over the entire operating temperature range to which it is exposed In good condition, that is, there is no visible phase separation or turbidity. Should be present in the right ratio. This fluid working substance is from -60 ℃ to + 175 ℃ Change. It is suitable if the fluid working substance remains in a single phase up to + 30 ° C. Often off, but single phase behavior is 40, 56, 71, 88 or 100 ° C The higher the temperature, the better if maintained up to. Similarly, fluid working substances It is often appropriate if C remains a single phase up to 0 ° C. Phase behavior must be up to -10, -20, -30, -40, or -55 ° C For example, the lower the temperature, the better. Chlorine-free hydrofluorocarbon coolant Single phase mixtures with fluid working substances are suitable and preferred types of the above esters. Usually obtained using.   How much lubricant is mixed with the heat transfer fluid to form a fluid working substance It is often difficult to accurately predict whether the lubricant composition A single phase in all proportions with the heat transfer fluid over a wide temperature range Is most preferred. However, this is a very strict requirement and the present invention A fluid-working substance mixture containing up to 1% by weight of the lubricant according to If there is a single-phase behavior, it is often sufficient. 2, 4, 10 and 1 lubricant It is better that the mixture containing up to 5% by weight behaves in single phase over the entire temperature range. preferable.   In some cases, single phase behavior is not required. The term "miscible" refers to frozen lubricant content. It is used in the field and is excluded hereafter in the case of the phase "miscible in all proportions". And two phases are formed, but at least mechanically with gentle stirring Is used when it is quickly mixed into a uniform dispersion. Refrigeration compressor (others (Including compressors) but some of the coolant fluid working substances and lubricants Some are designed to work well with such miscible mixtures. On the other hand, Mixtures that solidify or strongly thicken or form more than one phase are commercially acceptable. It is called "immiscible" here. Such mixtures described below Are all comparative examples and are not specific examples of the present invention.   Another key embodiment of the invention is that the lubricant contacts the refrigerating fluid working substance. As a total lubricant or lubricant base material in the refrigerator operation All uses of the lubricant of the present invention.   Further understanding of the practicality of the present invention by considering the following examples and comparative examples Can be evaluated.   General ester synthesis procedure   The reacted alcohol and acid are mixed with dibutyltin diacetate, tin oxalate, and Stirrer, heat with a suitable catalyst such as acid and / or tetrabutyl titanate. Round bottom frass equipped with a thermometer, nitrogen introduction means, condenser and circulating trap I charged it. The acid was charged in about 15 mol% excess over the alcohol. The amount of catalyst is It was 0.02 to 0.1% by weight of the total amount of the acid and alcohol to be reacted.   The reaction mixture is heated to a temperature between about 220 and 230 ° C to react the refluxing acid. The water generated by the reaction was collected in the trap while returning to the mixture. First per hour When it is necessary to achieve a reflux ratio of 8 to 12% of the reaction mixture, the above reaction mixture is used. The mixture was maintained at partial vacuum.   The reaction mixture was sampled from time to time to determine the hydroxyl number. Hi After the droxyl number was less than 5.0 mg KOH / g of mixture, the reaction While maintaining the temperature, the highest degree of vacuum possible with the equipment you are using Most of the excess acid was removed by distillation at a residual pressure of 1 bar. Then reaction mix Cool material and treat with lime, sodium hydroxide or epoxy ester if desired. The residual acid was removed by placing. The resulting lubricant or lubricant base The base material was dried and filtered before being subjected to the phase compatibility test.   General procedure for phase miscibility testing   Lubricant 1 ml (ml), diameter 17 mm (mm), length 145 mm Thermal shock capacity glass test tubes were placed. Plug the test tube It was placed in a cooling bath regulated at -29 ± 0.2 ° C. 5 minutes for the tube and its contents After equilibration in the intercooling bath, add sufficient coolant fluid working substance to add a total volume of 10 ml.   Cool tubes and contents for at least 15 minutes after adding fluid working substance It is in equilibrium in the bath and the contents may be stirred if desired. The contents of the tube were visually inspected for phase separation. If any phase separation occurs , Shake the tube and whether the combination can be evaluated as miscible or comprehensive I decided whether or not it was unacceptable.   At -29 ° C, if there is no evidence of phase separation, bath temperature until phase separation is observed Was lowered at a rate of 0.3 ° per minute. The temperature at which phase separation was first observed, if used If the temperature is within the range of the cooling device used, the temperature was recorded as the insoluble onset temperature. .   Specific example composition   Mixture of alcohol molecules, 99.9% of which are PE molecules and the rest are mostly DPE molecules The compound is 80% 3-methylbutanoic acid and 19% adipic acid, the remainder being mainly carbon atoms. By reacting with a mixture of acid molecules which are monobasic acids of An ester mixture was prepared. This ester mixture is approximately 900 centist at 40 ° C. It had a viscous viscosity.

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁶ Identification number Internal reference number FI C10N 40:30 (81) Designated country EP (AT, BE, CH, DE, DK, ES, FR, GB, GR , IE, IT, LU, MC, NL, PT, SE), CA, JP, KR

Claims (1)

[Claims] 1. A composition of matter suitable for serving as a lubricant or lubricant base stock, the composition being a liquid having a viscosity of from about 300 to about 1300 centistokes at 40 ° C., wherein at least about 92% of the alcohol portion is TMP. , DTMP, PE, DPE, TPE, and TTMP-derived alcohol moieties, wherein at least about 92% of the acyl groups have all straight and branched chain ones having from 4 to 12 carbon atoms. Consisting essentially of a mixture of polyol ester molecules selected from the group consisting of acyl groups of bases and dibasic carboxylic acids, the alcohol moiety and the acyl group further comprising (a) at least about 15 of the acyl groups in the mixture. % of the total weight of the acyl groups of i-C ₅ acid, (b) a branched chain and not greater than 6 carbon atoms Acyl% of the ratio of the mixture is a and unbranched 8 or more carbon atoms to the% of acyl groups in the mixture is from about 1 to have a child. Not greater than 56, and (c) the percentage of acyl groups in the mixture having at least 9 carbon atoms, which may be branched or unbranched, is not greater than about 81; (d) the acyl groups in the ester mixture. (E) at least about 13.8% of the acyl groups in the ester mixture are dibasic acids; no more than about 2% of the acid molecules having more than two carboxyl groups; The above composition, characterized in that the total amount of at least about 82% of the monobasic acyl groups therein is selected with the constraint that it has 5 or 6 carbon atoms. 2. Alcohol moiety and acyl groups (a) at least about 27% of the total weight of the acyl groups of i-C ₅ acid acyl groups in the mixture, the mixture having (b) a branched chain and not greater than 6 carbon atoms The ratio of% acyl groups in the mixture having 8 or more carbon atoms and being unbranched to the% acyl groups in the mixture is not greater than about 1.21, and (c) is branched or unbranched The percentage of acyl groups in the mixture having at least 9 carbon atoms is no greater than about 67; (e) at least about 15.3% of the acyl groups in the ester mixture are dibasic acids; Consisting essentially of a mixture of polyol ester molecules selected under the constraint that at least about 85% of the monobasic acyl groups therein have a total of 5 or 6 carbon atoms, and at 40 ° C. from about 450 to about 1100. The composition of claim 1 having a viscosity of centistokes. 3. At least about 95% of the alcohol moieties are selected from the group consisting of TMP, DTMP, TTMP, PE, DPE, and alcohol moieties derived from TPE, and at least about 95% of the acyl groups have from 4 to 12 carbon atoms. Consisting essentially of a mixture of polyol ester molecules selected from the group consisting of the straight-chain and branched-chain mono- and di-basic carboxylic acid acyl groups, wherein the alcohol moiety and the acyl group further comprise (a) said mixture at least about 36% of the total weight of the acyl groups of i-C ₅ acid acyl groups in the, (b) branched chain and is and the 8 or more relative% of the acyl groups in the mixture having no greater than 6 carbon atoms The ratio of% acyl groups in the mixture having carbon atoms and being unbranched is not greater than about 1.00, (c) branched The percentage of acyl groups in the mixture having at least 9 carbon atoms, which may or may not be present, is not greater than about 49, and (d) is not greater than about 1% of the acyl groups of the ester is 2 (E) At least about 16.2% of the acyl groups in the ester mixture are dibasic acids, which are from acid molecules with more carboxyl groups; at least about 93% of the one-base acyl groups in the acid mixture. A composition according to claim 2, characterized in that the total amount of is selected with the constraint that it has 5 or 6 carbon atoms. 4. Alcohol moiety and acyl groups is at least about 45% of the total amount acyl group i-C ₅ acid acyl groups in the mixture (a), (d) about 0.4% of the acyl groups in the ester mixture The lesser amount is from an acid molecule having more than two carboxyl groups, and (e) at least about 17 of the acyl groups in the ester mixture. Polyol ester molecules selected with the constraint that 0% has 5 to 7 carbon atoms with 2 bases and the total amount of at least about 96% of the 1-base acyl groups in the acid mixture has 5 carbon atoms. The composition of claim 3 consisting essentially of the mixture. 5. At least about 95% of the acyl groups are selected from the group consisting of straight-chain and branched mono- and di-basic all-carboxylic acid acyl groups having from 4 to 12 carbon atoms, the alcohol moiety and the acyl groups being ( a) a total amount of at least about 51% of the acyl groups in the ester mixture is an i-C ₅ acid acyl group, and (d) at least about 95% of the alcohol portion of the ester is of PE; ) Consisting essentially of a mixture of polyol ester molecules selected with the constraint that at least about 17.6% of the acyl groups in the ester mixture are dibasic, about 810 to about 990 centistokes at 40 ° C. The composition of claim 4 having a viscosity of. 6. At least about 95% by weight of the composition according to claim 5, the balance being oxidation resistance and heat stability improvers, corrosion inhibitors, metal deactivators, slip additives, viscosity index improvers, pour point and floc point depression. A compounded lubricant consisting essentially of one or more additives selected from the group consisting of agents, detergents, dispersants, defoamers, antiwear agents, and extreme pressure resistant additives. 7. At least about 92% by weight of the composition according to claim 3 with the balance being oxidation resistance and heat stability improvers, corrosion inhibitors, metal deactivators, slip additives, viscosity index improvers, pour point and floc point depression. A compounded lubricant consisting essentially of one or more additives selected from the group consisting of agents, detergents, dispersants, defoamers, antiwear agents, and extreme pressure resistant additives. 8. At least about 92% by weight of the composition according to claim 2, with the balance being oxidation resistance and thermal stability improvers, corrosion inhibitors, metal deactivators, lubricity additives, viscosity index improvers, pour point and floc point depression. A compounded lubricant consisting essentially of one or more additives selected from the group consisting of agents, detergents, dispersants, defoamers, antiwear agents, and extreme pressure resistant additives. 9. At least about 92% by weight of the composition according to claim 1, the balance being oxidation resistance and heat stability improvers, corrosion inhibitors, metal deactivators, lubricity additives, viscosity index improvers, pour point and floc point depression. A compounded lubricant consisting essentially of one or more additives selected from the group consisting of agents, detergents, dispersants, defoamers, antiwear agents, and extreme pressure resistant additives. 10. 10. At least 85% by weight of the basic heat transfer fluid selected from the group consisting of pentafluoroethane, 1,1-difluoroethane, 1,1,1-trifluoroethane, tetrafluoroethane and mixtures thereof, with the balance being 9. A coolant fluid working substance consisting essentially of the above lubricant. 11. 9. At least 85% by weight of the basic heat transfer fluid selected from the group consisting of pentafluoroethane, 1,1-difluoroethane, 1,1,1-trifluoroethane, tetrafluoroethane and mixtures thereof, the balance being 9. A coolant fluid working substance consisting essentially of the above lubricant. 12. 8. At least 85% by weight of the basic heat transfer fluid selected from the group consisting of pentafluoroethane, 1,1-difluoroethane, 1,1,1-trifluoroethane, tetrafluoroethane and mixtures thereof, with the balance being 7. A coolant fluid working substance consisting essentially of the above lubricant. 13. A coolant fluid working substance comprising at least 85% by weight of 1,1,1,1,2-tetrafluoroethane and the balance essentially consisting of the lubricant of claim 6. 14. 6. At least 85% by weight of the basic heat transfer fluid selected from the group consisting of pentafluoroethane, 1,1-difluoroethane, 1,1,1-trifluoroethane, tetrafluoroethane and mixtures thereof, with the balance being 5. A coolant fluid working substance consisting essentially of the above lubricant. 15. 5. At least 85% by weight of the basic heat transfer fluid selected from the group consisting of pentafluoroethane, 1,1-difluoroethane, 1,1,1-trifluoroethane, tetrafluoroethane and mixtures thereof, the balance being A coolant fluid working substance consisting essentially of the above lubricant. 16. 4. At least 85% by weight of the basic heat transfer fluid selected from the group consisting of pentafluoroethane, 1,1-difluoroethane, 1,1,1-trifluoroethane, tetrafluoroethane and mixtures thereof, with the balance being 3. A coolant fluid working substance consisting essentially of the above lubricant. 17． 3. At least 85% by weight of the basic heat transfer fluid selected from the group consisting of pentafluoroethane, 1,1-difluoroethane, 1,1,1-trifluoroethane, tetrafluoroethane and mixtures thereof, with the balance being 2. A coolant fluid working substance consisting essentially of the above lubricant. 18. At least 85% by weight of the basic heat transfer fluid selected from the group consisting of pentafluoroethane, 1,1-difluoroethane, 1,1,1-trifluoroethane, tetrafluoroethane and mixtures thereof, with the balance being 1. A coolant fluid working substance consisting essentially of the above lubricant. 19. A method of operating a refrigerator comprising circulating compression, liquefaction, expansion and evaporation of a heat transfer fluid, wherein the heat transfer fluid is at least 85% by weight of 1,1,1,2-tetrafluoroethane, the balance being A method of operating a refrigerator, characterized in that it is essentially derived from the above lubricant. 20. A method of operating a refrigerator comprising circulating compression, liquefaction, expansion and evaporation of a heat transfer fluid, wherein the heat transfer fluid comprises pentafluoroethane, 1,1-difluoroethane, 1,1,1-trifluoroethane, tetrafluoro A method of operating a refrigerator, characterized in that at least 85% by weight of the basic heat transfer fluid selected from the group consisting of ethane and mixtures thereof, the balance consisting essentially of the lubricant of claim 1.