Note: Descriptions are shown in the official language in which they were submitted.
~(~37~0
This inven-tion rela-tes to furlctional fluids having
improved viscosity characteristics.
Functional fluids have many applications. 'Ihey are
particularly useful as lubricants between moving mechanical
parts and as force transmission fluids, such as for example, ``-
as hydraulic fluids. In indiustrial uses of -these functional -
fluids, the viscosity is of utmost importance, due to the fact
that these products are commonly employed under wide ranges of
temperature. To obtain satisfactory performance, it is recom~
mended that the functional fluids possess a convenient viscosity-
temperature relation and a satisfactory flame resistance.
Many compounds and various compositions have already -~
been suggested as functional fluids. Tricresyl phosphates
have been used, but their viscosity index is negative. The `
viscosity index of a fluid is an indication of the viscosity
variation of the fluid as a function of the temperature and
: .
the most valuable products have a positive index. A negative `~
index for tricresyl phosphates indicates that these products ;~
are not useful throughout the temperature ranges normally a~
... . ~
encountered. ~- -
',':' ~'
Moreover, the viscosity of many phosphoric acid esters
is often too low for the conditions of use which are generally
required. To obviate this drawback, phosphoric acid esters
having a high molecular weight may be employed. However, the
viscosity characteristics at low temperatures are particularly
unfavorable for such high molecular weight materials. Another `~
known means for overcoming this disadvantage is by incorporating
- viscosity-index improvers, generally polymers such as poly-
methacrylates, polyolefines and the like. However, the flame -
resistance is substantially decreased.
~.
~ 7~
It is an object of the presen-t inven-tion -to provide new
fllnctional fluids contairling phosphoric acid esters. Ano-ther
object of the present invention is to provide functional
fluids possessing adequate viscosities at the wide range of
temperatures normally encountered in use. Still another ;~
object of the present invention is to provide functional
fluids having a low flammability.
According to the present invention, the functional
fluids essentially consist of~
A) an orthophosphoric acid ester of formula O = P ~ (OR)3,
wherein the R radicals, which may be the same or
different, are an aryl, an alkyl or an alkylaryl radical,
B) a transesterification product between a dihydroxy aromatic
compound and a phosphorous compound selected from the
group consisting of phosphorous acid esters of the formula
oR2 ,:~
R10 - P - oR3 and phosphoric acid esters of the formula
R10 - P - oR3, wherein the Rl, R2 and R3 radicals, which
oR2
may be the same or different, are an alkyl, an aryl or
an alkylaryl radical.
The components A of the composition hereinabove defined
are orthophosphoric acid esters of formula O = P = (OR)3 wherein
the R radicals, which may be the same or different, are an alkyl
radical generally comprising from l to 8 carbon atoms or an aryl
radical, which may have substituen-ts thereto. If a substituent ~ ~-
is present, it usually will be an alkyl radical having 1 to 8
carbon atoms. The selection of -the component A which is employed
for the production of the compositions of the present invention
depends on its properties, more particularly its viscosi-ty
characteristics, and also on its price. For instance, tricresyl
phosphate, trioctyl phosphate, diphenyl-cresyl-phosphate,
-2-
.... .
.. . . , - -
: 3 ~375~4V ;`
phenyl-dioctyl-phospha-te and the like may be used. For some
applica-tions, phosphoric acid esters con-taining ethylphenyl
radicals are particularly useful; such es-ters already have a -
high viscosity index, which is substan-tially improved by
adding the Component B, hereinabove defined.
The Components B of the composition above defined are
transesterification products of a dihydroxy aromatic compound
and a phosphorous acid ester or a phosphoric acid ester. `~
Hydroquinone, resorcinol, pyrocatechol, 2,2'-bis(4-hydroxy-
phenyl)propane (or bisphenol-A) and bis (~-hydroxyphenyl)
methane generally are used as dihydroxy aromatic compounds.
The dihydroxy aromatic compound is transesterified by a
phosphorous acid ester
R O - P - OR or a phosphoric acid ester R O - P - OR , `~
oR2 oR2
wherein the Rl, R2 and R3 radicals, which may be the same or
different, are an alkyl, an aryl or an alkylaryl radical.
Preferably, the R , R and R radicals are alkyl radicals - ;
containing from 1 to 12 carbon atoms, an aryl radical or an -
alkylaryl radical where the alkyl substituent contains from 1 ~ ~ -
20 to 8 carbon atoms. According to a preferred embodiment of `~
this invention, the phosphorous acid ester or the phosphoric
acid ester comprises at least two aryl or alkylaryl radicals.
More preferably, these esters are triphenyl phosphate, tri- `~
cresyl phosphate, trixylyl phosphate, tri(m-ehtylphenyl) ~ -
phosphate or diphenyl-decyl-phosphate.
The precise composition of the transesterification
products is not yet known. Moreover, the molecular weight of
these products may be varied according to the molar ratio of
the reactants. Products with a high molecular wei~ght are
prepared when the molar ratio is 1. A higher molar proportion
of any one of the reactants gives rise to products with a
037~4V
lo~ver molecular weight. In order to avoid the produc-tion of
transesterifica-tion products containing residual dihydroxy
aromatic compounds, the transesterif`ication reaction is
preferably carried out with a molar excess of phosphorous
compound. This excess may be high; however, an excess higher
than two moles of phosphorous compound per mole o~ dihydroxy
aromatic compound is of no advantage, either technically or
- economically. -
One or more monohydroxy compounds may be formed as a
by-product during the transesterification reac-tion. ~or
instance, when triphenyl phosphate is used for the transesteri-
fication reaction, phenol is formed simultaneously with the
transesterification product. In order to shift the reaction
equilibrium, it is advantageous to remove the monohydroxy
compound as soon as it is formed. This shifting of the
equilibrium may be performed by using any known method, for ~-
instance by stripping and/or by carrying out the transesteri-
Eica-tion reaction under vacuum. Basic compounds, such as
alkaline metals, alkaline hydroxides, alkaline phenates or -`
alcoholates and the like are catalysts for the transesterifi- `~
cation reaction. This reaction is carried out at a temperature
which generally is of from about 100 to 200C.
The viscosity of Components A is noticeably improved
by adding Components B or transesterification products. The
amount of Component B added largely depends on -the particular
Component A employed, on the particular Component B used and
on the desired degree of improvement. However, Component B
generally is used in an amount of between 1 and 50% based
on the weight of Component A, more particularly in an amount
between 1 and 20% by weight.
The functional fluid compositions of the present in-
vention may have their properties further improved by adding
-.:-~: .:. . . . . .
~37~
there-to an oily material in which these mix-tures are soluble.
Chlorinated diphenyls are very in-teres-ting oils, more
particularly for the manu~acture of hydraulic ~luids having a
high flame resistance. The relative proportions of -the oily
material and of the functional fluid mixture of Components A
and B may vary within wide limits, depending upon -the particular
intended use. For instance, fire resistant hydraulic fluids
are prepared by mixing 70 to 95% by weight, of the mixture of `~
components A and B and 30 to 5% by weight of chlorinated bi~
phenyl. Other valuable fluids contain a major propor-tion of
oily material and a minor proportion of the mixture of ;
Components A and B.
Other valuable properties can also be imparted to -the
functional fluids of the present invention by the op-tional -
addition of certain other additives. Typical additives are,
for example, foam inhibitors, rust inhibitors and antioxidan-ts.
Such additives generally are employed in quantities of from O `
to 3% based on -the weight of the functional fluids. As an anti~
oxidant, it is preferred to use arylamines and alkylphenols,
typically di-tert butyl-phenol or di-tert butyl-cresol. These
materials usually are employed in quantities from abput 0.05 to
1% by weight. As rust inhibitors, higher alkyl malonic or
succinic acids and alkaline-earth metal su~fonates may be used,
generally in quantity up to 1% by weight and preferably in
quantity of 0.01 to 0.5% by weight. Silicones, alpha-chloro~
naphthalene and other known foam inhibitors may be added to the ;
functional fluids in an amount of from 0.5 to 2% by weight.
The following examples are present to illustrate the
present invention:
7~
;~) Prep~r~Ltioll of thc transe~riPical:ion product.
0.3 mole oL tril~henyl pll~spll~te alld 0.15 mole o~
bisphellol A ~ere added ullder ~gi~ation to a reactor. 0.5 g.
o~ sodium hydl~oxide was then adAed and tlle mixture he~ted
under pressure of 10 mm. ~Ig. Phenol distilled o:ef at about
115C. The heating was carried up to ~80C. A viscous,
oily product was obtained in substantially quantitative
yield. This product had a molecular weight of 1405 and the
elemental composition ~vas:
C calculated: 68.3% C found: 67.35%
H calculated: 5.05% H found: 5.72%
P calculated: 8.7% P found: 8.50%
b) Preparation of functional fluids.
Various amounts of -the above transesterificatlon
product prepared in (a) above were added to tricresyl
phosphates as shotvn in Table I below. The viscosities and
viscosity indexes which are given in Table I below clearly
show that the viscosity index is increased by adding the
20 transesterification product referred to in the Table as "T.P."
TABLE I
Viscosity
Functional fluid Engler Centistokes Centistokes ~Tiscosity
- at 50C at 100F at 210F index
_______________________________________________________________
TCP (a) 2.44 28.25 3.96 - 44
TCP + 1% T.P. (b) 2.67 32.04 4.48 18
TCP + 3% T.P. 3.04 38.46 5.03 38
TCP + 5% T.P. 3.47 44.46 6.18 ~2
TCP + 10% T.P. 4.89; 66.87 7.56 79
TCP + 30~ T.P. 16.70 263.9 20.19 95
: . _
7~
'I`he improvement which is noticeable when the amount
of transesteri~ication product is as low as about 1%, is
particularly noticeable when this amount is about 5%, based
on the weigh-t Or tricresyl phosphate as may be seen from ~ -~
Table I above. Large amounts of transesterification product,
such as for instance amounts higher than about 25-30%, do
not give rise to a further improvement.
The flame resistance of tricresyl phosphate is not
altered when the transesterification product is added. For
10 example, practically pure tricresyl phosphate, on one hand, ~; -
and tricresyl phosphate containing 5% of transesterification
product, on the other hand, have the same spontaneous ignition ;
temperature, i.e., 560C.
Example 2
'~
The method described in Example 1 was repeated for the
manufacture o-E various transesterification products. Each of
these transesterification products was added to tricresyl
phosphate in amount of 5% based on the weight of said phosphate.
The particular transesterification product and the properties
resulting from their use are summarized in Table II below.
TABLE II
Viscosity of the mixture
Transesterification product
(added to TCP) Engler Centi- Centi-Viscosity
at 50 C stokesO stokes index
at 100 F at 210 F
... : .
Bisphenol A + tricresyl -
phosphate 3.47 44.46 6.18 62
Bisphenol A + tri(m-ethyl-
phenyl)phosphate 3.16 40.30 5.31 55 --~
30 Bisphenol A + triphenyl
phosphite 2.99 38.09 4.75 0
Bisphenol A + tri(nonyl-
phenyl)phosphite 2.89 35.66 4.56 - 9
Bisphenol A + diphenyl-
octyl-phosphite 2.69 32.74 4.43 0
Hydroquinone + tricresyl
phosphate 2.60 31~30 4.31 - 4
~:
-7-
~37~0
Exam~le 3
The transesterification product obtained from bis-
phenol-A and triphenyl phosphate was added to various aryl
phosphates, in an amount corresponding to 5% of the weight
of said phosphates. The particular aryl phosphates and the
viscosity index of the resulting functional fluids are
summarized in the following Table III.
TABLE III
Functional fluid Viscosity index
10 Tri(m-ethylphenyl)phosphate 108
~ 5% P.T. 135 - 136
Diphenyl-m-ethylphenyl phosphate 75
" " + 5% P.T. 114 - 115
Diphenyl-cresyl-phosphate 30
15 ~- + 5% P.T. 86 - 87
Phenyl-dioctyl-phosphate 67 ;
l~ + 5% P.T. 91
Example 4
Functional fluids were prepared by adding various
transesterification products ~T.P.) to diphenyl-cresyl-
phosphate, the amount of T.P. corresponding to 5% of the
weight of said phosphate. The particular T.P. added and the
viscosity index of each mixture is gi~en in Table IV below.
The viscosity index of diphenyl-cresyl-phosphate is 30.
TABLE IV ~
Transesterification product (addedViscosity index ~ ;
to diphenyl-cresyl-phosphate) of mixture
Bis(4-hydroxyphenyl)methane +
tricresyl phosphate 100
30 Hydroquinone + tricresyl phosphate 40
Resorcinol + tricresyl phosphate 46
::
Pyrocatechol + tricresyl phosphate 52
Example 5
A composition was prepared by mixing 85% (by weight) of
; 35 tri(m-ethylphenyl)phosphate, 5% of the transesterification
:- :
.- .- ., ~ . , .. , .... . - , -
~ 7~4(3 : ~
product between bis~phenol-A and tricre~yl phosphate and 10%
of chlorinated biphenyl ('~2% o~ chlorine). To this mix-ture
was added 5% (by weight of the mixture) of` di-tert-butyl-
paracresol and 0.1% of calcium petroleumsulfonate. The
resulting composition was a fire resistant hydraulic fluid. `
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