FI107341B - Complex esters for use with fluorinated coolants - Google Patents

Description

107341

Complex esters for use with fluorinated coolants

The present invention relates to a coolant composition according to claim 1. Such a composition will generally contain a non-chlorinated hydrofluorocarbon-based coolant 5 and a mixed polyol ester-based lubricant,

The development of polyol ester-type lubricants has recently been rapid due to developments in a number of applications. These products can be used as such as a base lubricant, for example in aircraft and gas turbine engines, or as a blend with hydrocarbon based lubricants, biodegradable hydraulic oils, compressor oils, metalworking oils, and especially fluorinated coolants, soluble lubricant and lubricant lubricant components.

15 It has been proposed to be commonly used with coolants, e.g. esters of neopentylglycol and pentaerythritol. Although these known esters have generally good lubricating properties, their solubility in chlorofluorocarbons is in most cases only satisfactory. As a result, they do not perform well enough in coolant compositions containing just fluorinated hydrocarbons.

20: · '·' The object of the present invention is to eliminate the drawbacks of the known solutions and to provide novel polyol-based esters which can be used in particular.

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'.,. fluorinated coolants as lubricants.

The invention is based on the discovery that complex esters of chemically and technically stable diols act as excellent lubricants in fluorinated refrigerant compositions. These esters have good lubricant properties: · and are also highly or very soluble in fluorinated coolants. In particular:. lubricants used are complex esters made from neopentyl glycol, 2-. ···. 30 ethyl-1,3-hexanediol or 1,4-dimethylol-cyclohexane from a mixture of monovalent and divalent carboxylic acid.

More specifically, the refrigerant composition of the invention is essentially characterized in what is set forth in the characterizing claim of claim 1.

The invention provides considerable advantages. In addition to having good lubricant properties and good solubility in HFCs used as coolants, the complex esters are also economically advantageous because their diol components can be produced by the oxo process (hydroformulation). In addition, the properties of the oils may be well modified according to the application by varying either the polyol contained in the ester or, if more polyols are used, the ratio of polyols, the esterifying carboxylic acid and / or the ratio of esterifying carboxylic acids.

The invention will now be explored in greater detail by means of the detailed description 15 and a few embodiments.

The present esters comprise esters of a chemically and technically stable diol in which at least some of the esterifying carboxylic acids are divalent. Typically, both carboxyl groups of these acids react with alcohols to yield oligomeric ester compounds containing two alcohol residues and one carboxylic acid residue. Complex esters also include those esters having the form of a carboxylic acid residue: aa · · · · * * hydroxy acids in which both a hydroxyl group and a carboxylic acid group are present.

• · * * / '. The carboxyl group is then reacted with e.g. a polyol and the hydroxyl group is reacted with any 1 · · * «· *! with the carboxyl group of the carboxylic acid.

* · ·: ·. 25 i * * * «| . ·· *. "Polyol" means a compound having at least two hydroxyl groups

according to ETHD or CHDM may be esterified in admixture with one another or with another j: polyol. The latter include, for example, NPG (neopentylglycol), H) 'IP

:, · (Hydroxypivalyl hydroxypivalate), TMP (trimethylolpropane), TME (trimethylolefe), PE (pentaerythritol), TMPD (2,2,4-trimethylpentanediol) and 2-butyl-2-ethyl-1,3- propanediol. i: • I «• i * · j * * *, I ·« · * 1 * 0! 107341 3 In "chemically and technically stable" polyols 2-carbon there is no hydrogen or hydrogen is sterically hindered. Examples of these compounds are NPG, ETHD and CHDM. The formulas of the compounds in question are: p

OH

NEOPENTYL GLYCHOL 2-ETHYL-1, 3-HEXANIDIOL

NpG ETHD

10

1,4-cyclohexanedimethanol

CHDM

15

As the graphs show, the 2-carbon of chemically and technically stable esters has no hydrogen atom or has only one hydrogen atom. In the latter case, however, the 2-carbon is accompanied by a larger group which renders the hydrogen sterically hindered and does not readily hydrolyze. The invention relates in particular to esters of ETHD and CHDM.

20

If the diol or polyol residue of the ester contains a mixture of two different diols, the first * *. the molar ratio of the diol to the second polyol, if present, is from 5: 95 to 100: 0.

Preferably, in the ester mixtures of the invention, the first diol forms the major part of the polyol residue of the esters, particularly preferably at least 0.5 (e.g. 0.5 ... 1). 25 »* <ETHD and CHDM or a mixture of ETHD and CHDM and another polyol is esterified with a linear or branched C4-C18 carboxylic acid or its anhydride. As examples of aliphatic, linear or branched, saturated or unsaturated C 4 -C 8 carboxylic acids which can be used to prepare the esters, the following may be mentioned: - C 4 -C 18 saturated linear carboxylic acids, butyric acids ), pen- / ": Tanoic acid (valeric acid), Hexanoic acid (caproic acid), Heptanoic acid, Ox- * * * 107341 4 Tanoic acid (Caprylic acid), Decanoic acid (Capric acid), Dodecanoic acid (Auralic acid) and Hexanoic acid mixtures thereof, saturated C4-C16 branched carboxylic acids: isobutanoic acid, 2-ethylhoxanoic acid, iso-nonanoic acid and 3,5,5-trimethylhexanoic acid; 5-unsaturated linear C4-C15-carboxylic acids: unsaturated, branched C4-Cl8 carboxylic acids.

In mixed esters, the ratios of the various linear and branched carboxylic acids may vary over a wide range. Typically, the linear (linear) carboxylic acids will be present in an amount of from 1 to 100 mol% of the amount of carboxylic acids, preferably from about 10 to 90 mol%. The branched carboxylic acids are respectively 99 to 1 mol%, preferably about 9 to 10 mol%. In particular, it is possible to prepare polyol esters containing from 10 to 50 mol% of at least one linear carboxylic acid; and 90-50 mol% branched carboxylic acid.

15 j

Among the esterifying hydroxy acids, the following can be mentioned: hydroxypivalic acid (ΗΡΑτ)), lactic acid, citric acid dimethylolpropionic acid (DMPA). I

In addition to the above, the esterifying carboxylic acid used is a dibasic carboxylic acid such as oxalic acid, malonic acid, dimethylmalonic acid, succinic acid. acid, glutaric acid, adipic acid, pimelinic acid, suberic acid or azelanic acid).

A cyclic anhydride such as succinic anhydride or its

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i * · ·. ·. alkyl derivative, or trimellitin anhydride. Aromatic anhydrides, such as phthalic anhydride, are also possible in small amounts.

25! The degree of esterification of the polyols is 50 to 100%, preferably as high as possible, at least no; n 90%. In the esters, the ratio of monobasic and dibasic carboxylic acids is 50: 50 to 95: 5 9 · 1 · · · · · · · · · · · · Technically and chemically stable complex esters can be used to prepare cooling liquid compositions. These contain a non-chlorinated hydrofluorocarbon as a refrigerant. Exemplary 9 * 9 characters for the hydrocarbon component of the compositions include: fluorocarbon 134 (1,1,2,2-tetrafluoroethane), fluorocarbon 134a, fluorocarbon 143 (1,1,2-trifluoro-107341 5-ethane), hydrofluorocarbon 143a (1, 1,1-trifluoroethane), hydrofluorocarbon 152 (1,2-difluoroethane) or hydrofluorocarbon 152a (1,1-difluoroethane). Of these compounds, hydrofluorocarbon 134a is generally preferred. Mixtures of hydrofluorocarbons may also be used. Examples include hydrofluorocarbon mixture 407 (hydrocarbon 32, 125, and 134a) and hydrofluorocarbon 5 blend 410 (hydrocarbon 32 and 125).

According to the application, the ISO standard viscosity required for Ester ranges from 5 to 200 cSt (40 ° C). Low (5 - 10) and medium (22 - 32) viscosities are required in refrigerators and other smaller refrigeration equipment. High viscosity 10 (46-68) applications are required, for example, in air-conditioning refrigeration equipment and very high viscosity is required in large installations.

As already stated at the beginning, the viscosity of the esters to be prepared can be desirable by appropriately selecting the esterifying carboxylic acid components and / or by adding another 15 polyols to ETHD or CHDM. Thus, conventional linear and branched carboxylic acids (C4-C12) and e.g. adipic acid produce esters having viscosities of about 5 to 90 cSt at 40 ° C. The viscosity indices are about 100 and the pour point is below -40 ° C. Their porosity to fluorinated coolants is usually excellent. They are suitable for both smaller refrigeration units and air conditioning units. By using linear hydrocarbons in combination with divalent acids. . in general, lower viscosity values are obtained than by combining branched hydrocarbons and divalent acids.

Examples of particularly preferred esters include: 25: complex esters of ETHD containing from 1 to 40 mol% of dibasic carboxylic acid and from 60 to 99%. molar% of linear and / or branched monovalent carboxylic acid; and • · · •, .. complex esters of CHDM containing 4-30 mol% of dibasic carboxylic acid and 96-70 mol% of linear and / or branched monovalent carboxylic acid. / · 30 fatty acids.

: Conventional additives can be used in coolant compositions such as: 6! h j: 1073 ^ 1 antioxidants, anti-wear agents, detergents, anti-foaming agents and anti-corrosion agents.

Suitable antioxidants include phenols such as 2,6-di-t-butyl-4-methylphenyl and 4,4'-methylene-bis (2,6-di-t-butylphenol); aromatic amines such as ρ, ρ-dioctylphen; j-liamine, monooctyldiphenylamine, phenothiazine, 3,7-dioctylphenothiazine, phenyl ··· naphthylamine, phenyl-2-naphthylamine, alkylphenyl-1-naphthalamines and alkylphenyl-2-naphthalamines, and sulfur-containing compounds, phosphites, sulfides and dithiomtall salts such as benzothiazole, tin dialkyl dithiophosphates and zinc diaryl dithiophosphate 1 °

Suitable anti-wear agents are e.g. phosphates, phosphate esters, phosphites, tiofosfiitit, j, such as zinc dialkyldithiophosphate, zinc diaryldithiophosphate, tricresyl phosphates, chlorinated waxes, faktisoidut fats and olefins, such as tiodipropionihappoesterit, dialkyl isukit it, dibenzylsulfide, dialkyl, alkyl mercaptans, dibentsentiofeenit and 2; 2'-15 dithiobis (netsothiazole); organic lead compounds, fatty acids, molybdenum complexes such as molybdenum disulfide, halogen-substituted organic silicon compounds, borates and halogen-substituted phosphorus compounds.

•. Examples of suitable detergents are sulphonates, aromatic sulphonic acids,. 20 substituted with long chain alkyls, phosphonates, thiophosphonates, phenol a it, «e *« | ; * metal salts of alkylphenols and alkylsulfides.

Typical antifoam agents are silicone oils, e.g., dimethyl polysiloxanes, and O -! : ganosilicates, such as diethyl silicates.

Examples of corrosion inhibitors are organic acids, amines, phosphates, alcohols, sulfonates and phosphites.

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The esters of the invention are prepared by a conventional esterification reaction in which a poly silicon or a mixture of polyols is reacted with an acid mixture. Suitable for the invention are the esterification catalysts. are various acids such as sulfuric acid, hydrochloric acid, p-toluene sulfonic acid, butyltinate, tin oxide, etc. Particularly suitable for the invention is the zinc-tin oxide catalyst.

In the reaction step, the polyol is reacted with the acid components using an excess acid (0-10 mol%), preferably about 0.1-5 mol%, particularly preferably about 1 mol%. The reaction temperature is 150-230 ° C, preferably 170-220 ° C, and particularly preferably about 190-210 ° C.

The esterification can be carried out by batch or half-batch reaction, for example, so that the rest of the acid is added later. At its most typical, esterification is carried out in the molten state, but the use of 10 hydrocarbon-type media such as toluene or xylene is possible. The product is neutralized and washed. The purity of the ester product is preferably greater than 85%, in particular greater than 90%, and the acid number of the ester is preferably less than 0.1 mg KOH / g.

The following examples illustrate the invention. However, they do not limit the scope of the invention.

Example 1

Determination of solubility of esters «·.:. The solubility in fluorinated hydrocarbons is determined as follows: 1 ml of the ester to be tested:. ·. is measured into a test tube and the cap is closed. Place the test tube in a cold bath at -30 ° C to 4 ° C; After the temperature of the test tube and ester has stabilized at -30 ° C (after about 5 minutes: * · ..), a chilled coolant such as R-134a is added so that the total volume of the mixture is 10 ml.

25 • ·: * * The ester refrigerant mixture is allowed to stand in the bath at -30 ° C, possibly with gentle stirring. After about 15 minutes, the mixture is visually inspected.,! Γ and observe whether the mixture is in one or two phases. If the ester and cooling * ... 'form a single phase, the ester is completely dissolved in the refrigerant. If the mixture contains two phases, the ester is either partially or completely insoluble in the refrigerant.

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Example 2 [ii] Complex ester of NPG, hexanoic acid and adipic acid j

The raw materials were weighed into a glass flask according to the following protocol: NPG 35.0 g, hexane hept 5 71.2 g and adipic acid 4.8 g. 0.17 g of tin oxide was used as catalyst. The esterification was effected by stirring and nitrogenizing the reaction mixture at about 200 ° C. The reaction was complete within 7 hours.

The reaction mixture was neutralized with excess acid acid with 2.8 g of solid sodium carbonate.

Neutralization was performed at 200 ° C and lasted 5 hours. Sodium carbonate and tin oxide were removed from the product by filtration. Finally, the product was dried over sodium sulfate and filtered.

Other esters were prepared from NPG, ETHD, CHDM, and isobutanoic acid, 15 pentanoic acid, hexanoic acid, 2-ethylhexanoic acid, lauric acid and adipic acid Posta, respectively. The results are summarized in Table 1j:

Table 1. Complex Esters • e 9 11 j “I Hl 'l | I - --- S v

«I

20 Sample Polyol Acid η40ΟΟ r100 ° C VI JP Solubility i **: (mol%) (mol%) (cSt) (cSt) (° C) R-134a: har, 9 4a II II I · - UI I - ^ »· Ι im" mm • · · "'1 NPG (100) C5 (95) 6.2 2.0 118 -72 Excellent: r: ___aa (5) _____________ i • ·" "2 NPG (100) C5 (93) 7.2 2.3 141 -69 Excellent: ___ AA (7) ___________ 3 NPG (100) Ci-4 (82) 11.7 3.1 125 -60 Excellent AA (18) • · ·: 4 NPG (100) Cl2 (23) 17.1 4.1 152 -36 Excellent

Ci-4 (59) AA (18) '·: * 25 5 NGP (100) C8 (95) 9.9 2.8 137 - Good ·: ··: ___AA (5) _________________ 6 NPG (100) C6 ( 95) 6.4 2.0 10, -72 Excellent 1 AA (5) _____11 ,, 1 107341 9 7 ETHD Ci-4 (86) 12.7 2.9 56 -58 Excellent __ (100) __ AA (14) ______ 8 ETHD Ci-4 (82) 14.9 3.3 77 -58 Excellent __ (100) __ AA (18) ______ 9 ETHD Ci-4 (67) 85.8 10.7 108 -44 Excellent __ (100) __AA (33) ______ 10 CHDM 2-EHA 21.7 4.0 61 -54 Excellent (100) __ (100) ______ 5 AA = Adipic acid C1-4 = Isobutanoic acid C5 = Pentanoic acid 10 C6 = Hexanoic acid 2-EHA = 2- Ethylhexanoic acid C12 = Lauric acid «·« · • · Γ \.

* • · · »·« • · • • • ««

Claims (8)

10 I 107341 A refrigerant composition comprising a refrigerant comprising a hydrofluorocarbon and a mixed polyol ester based lubricant, characterized in that the polyol ester based lubricant comprises 2-ethyl-1,3-hexanediol or 1,4-dimethyl-1-cyclohexane, which is esterified with a mixture of monobasic and dibasic carboxylic acids. A refrigerant mixture according to claim 1, characterized in that the lubricant 10 contains at least one ester of another polyol. A refrigerant mixture according to claim 1 or 2, characterized in that the proportion of the 2-ethyl-1,3-hexanediol or 1,4-dimethylol-cyclohexane in the ester is at least 0.5. 15 A refrigerant mixture according to claim 3, characterized in that the polyol residue of the second polyol ester of the lubricant is derived from 2-butyl-2-ethyl-1,3-propanediol, neopentylglycol, hydroxypivalylhydroxypivalate, 2-ethyl-1,3-hexanediol, trimethylolpropane, , pentaerythritol or 2,2,4-20 trimethylpentanediol. A refrigerant mixture according to any one of the preceding claims, characterized by a hedgehog, wherein the monovalent carboxylic acid residue of the ester is derived from linear or branched carboxylic acids, anhydrides or mixtures thereof. 4. A refrigerant mixture according to any one of the preceding claims, known as, • * | that the divalent carboxylic acid residue is derived from oxalic acid, malonic acid. ; . ···. dimethylmalonic acid, succinic acid, glutaric acid, adipic acid, pimeliir iba-. Post, suberic acid or azelanic acid, or a cyclic anhydride such as succinic anhydride or an alkyl derivative thereof, or trimellitic anhydride. j A refrigerant mixture according to any one of claims 1 to 6, characterized in that the molar ratio of monobasic and dibasic carboxylic acids in the mixture is 50: 50 to 95: 5. 8. A refrigerant mixture according to any one of the preceding claims, characterized in that the fluorinated hydrocarbon-based coolant is fluorocarbon 134, fluorocarbon 134a, fluorocarbon 143, fluorocarbon 143a, fluorocarbon 152 or fluorocarbon 152a or a mixture of hydrocarbons. • • • «• * • • • • • • • • ••••••••••• J 10734 Ί