Note: Descriptions are shown in the official language in which they were submitted.
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FOOD GRADE LUBRICANT COMPOSITIONS
TECHNICAL FIELD
[001] The embodiments described herein relate to food grade lubricant
compositions
and in particular to lubricant compositions that exhibit improved sludge
control
properties compared to conventional food grade lubricants.
BACKGROUND
[002] The equipment used in the food processing industry varies by segment
with
the three leading segments comprising meat and poultry, beverages, and dairy.
While
the equipment varies from segment to segment, the moving parts such as
bearings,
gears, and slide mechanisms are similar and often require lubrication. The
lubricants
most often used include hydraulic, refrigeration, and gear oils as well as all-
purpose
greases. However, food industry oils must meet more stringent standards than
other
industry lubricants.
[003] Lubricant contamination has been a problem in the food and beverage
processing industry, where a major accident could require a company to make a
massive product recall, which could be devastating to its reputation.
[004] Minor lubricant leaks in machinery are common, sometimes unavoidable,
and
not always obvious. Just the normal wear and tear on seals can cause a gearbox
or
hydraulic system to leak, releasing minute levels of oil that can come into
contact
with food. Contamination can also come from drips from chains or a release of
compressed air that contains an oily mist.
[005] If a plant uses a nonfood-grade lubricant, the U.S. Food and Drug
Administration (FDA) allows zero amounts of lubricant to come into contact
with the
food. If the lubricant accidentally comes into contact with food, the batch
must be
discarded. If the plant uses food-grade lubricants, which are nontoxic,
odorless,
colorless and tasteless, the FDA limits lubrication contamination to 10 parts
per
million.
[006] The Food Safety and Inspection Service (FSIS) is custodian of the
official list
of authorized compounds for use in federally inspected plants. The official
list states
that lubricants and other substances which are susceptible to incidental food
contact
are considered indirect food additives under USDA regulations. Therefore,
these
lubricants, classified as either H-1 or H-2, are required to be approved by
the USDA
before being used in food processing plants. The most stringent
classification, H-1, is
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CA 02605903 2007-10-04
for lubricants approved for incidental food contact. Lubricants meeting the H-
1
classification are used where food may potentially be exposed to the
lubricated part of
the machine. The H-2 classification is for uses where there is no possibility
of food
contact and assures that no known poisons or carcinogens are used in the
lubricant.
For the purpose of this disclosure, the terms "food grade" and "lubricant"
will be used
interchangeably herein.
[007] In addition to meeting the requirements for safety set by federal
regulatory
agencies, the lubricant must be effective for the particular application and
may also be
required to meet Kosher and Halal requirements. Lubricating oils for food
processing
plants should lubricate machine parts, resist viscosity change, resist
oxidation, protect
against rusting and corrosion, provide wear protection, prevent foaming, and
resist the
formation of sludge in service. The product should also perform effectively at
various
lubrication regimes ranging from hydrodynamic thick film regimes to boundary
thin
film regimes. Lubricants which can meet or exceed DIN 51524 part II
specification
may meet the foregoing performance criteria. Conventional food grade
lubricants
contain antiwear agents. Of the antiwear agents used in food grade
applications,
certain amine salts of acid phosphates may result in increased sludge/varnish
formation. It is, therefore, desirable to provide an improved food grade
lubricating oil
which overcomes the sludge and varnish tendencies of conventional food grade
lubricants.
SUMMARY OF THE EMBODIMENTS
10081 In one embodiment herein is presented a food grade lubricant composition
including a major amount of food grade base oil and a minor amount of at least
one
additive composition. The additive composition includes one or more non-sludge
promoting wear reducing agents. An advantage of the lubricant composition is
that it
may exhibit lower sludge formation tendencies than a lubricant composition
containing a conventional wear reducing agent.
[009] In another embodiment, there is provided a method of operating machinery
for
food processing. The method includes providing the machinery with a food grade
lubricant containing a major amount of food grade base oil and a minor amount
of an
additive composition and operating the machinery. The additive composition
includes
one or more non-sludge promoting wear reducing agents. During operating of the
machinery on the lubricant, the lubricant composition may exhibit lower sludge
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formation tendencies than a lubricant composition containing a conventional
wear
reducing agent.
[0010] As set forth briefly above, embodiments of the disclosure may provide
an
improved food grade lubricant composition that exhibits reduced sludge and/or
varnish formation, and meets the wear criteria for food grade lubricants.
Other
features and advantages of the compositions and methods described herein may
be
evident by reference to the following detailed description which is intended
to
exemplify aspects of the embodiments without intending to limit the
embodiments
described herein.
[0011] It is to be understood that both the foregoing general description and
the
following detailed description are exemplary and explanatory only and are
intended to
provide further explanation of the embodiments disclosed and claimed.
DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS
[0012] According to exemplary embodiments described herein, there is provided
an
improved food grade lubricant composition that may be particularly effective
for
reducing sludge and varnish formation, and may meet the H-1 and/or H-2
requirements for use in food processing industries. The exemplary food grade
lubricants are also suitable for providing good wear protection, suitable
protection
against rust and corrosion, and good foam and air release properties. As set
forth
above, the lubricant composition includes a food grade base oil.
[0013] The base oil for use in the food grade lubricating oils described
herein may be
selected from food grade hydrocarbon oils such as food grade mineral oil, food
grade
polybutene, food grade hydrogenated polybutene, food grade polyolesters, food
grade
diesters, food grade hydrogenated poly(alpha olefin) with an alpha olefin
monomer of
not less than 6 carbon atoms, and a wide variety of vegetable oils. The base
oil
should be substantially odorless, colorless, and tasteless and comply with the
USDA
H-1 and/or H-2 specifications and requirements for use in food processing
plants and
other applications.
[0014] In one exemplary embodiment, the base oil may be a mineral oil such as
a
technical grade white oil made from select lubricant base stocks. The food
grade
mineral oil may also be a white mineral oil which meets the more stringent
requirements of the United States Pharmacopeia (USP) or a light mineral oil
which
meets the more stringent requirements of the National Formulary (NF). These
food
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grade mineral oils are often directly derived from crude oil through the
processing
steps of distillation, extraction, dewaxing, and severe hydrotreating.
Suitable base
oils, derived from other means are food grade polybutene, food grade
hydrotreated
polybutene, food grade polyolesters, food grade diesters, and food grade
hydrogenated poly(alpha olefin) with an alpha olefin monomer of not less than
6
carbon atoms.
[0015] Vegetable oils may also be used as the base oil component, either alone
or in
combination with the foregoing oils. Suitable vegetable oils may include, but
are not
limited to, rapeseed oil, jojoba oil, tung oil, castor oil, tall oil, linseed
oil, olive oil,
peanut oil, rope oil, coconut oil, soybean oil and mixtures thereof. Oils
derived from
meat products, such as lard oil, tallow oil, mink oil, and the like are
avoided for
lubricant applications meeting Kosher and/or Halal requirements.
[0016] The base oil comprises from about 85.0% to 99.9% by weight of the
lubricant
composition containing additives to provide a product having a viscosity
ranging from
cSt at 40 C. to 1000 cSt at 40 C. The additives used may suitably meet the
HX-1
criteria for providing H-1 food grade lubricant compositions and may meet the
HX-2
criteria for providing H-2 food grade lubricant compositions.
ANTI-WEAR ADDITIVES
[0017] Anti-wear additives which may be used in the compositions described
herein
include food grade oil-soluble sulfur and/or phosphorus containing compounds
and
neutralized alkyl phosphate esters, and mixtures of the foregoing.
[0018] One sulfur and/or phosphorus compound that may be used is triphenyl
phosphorothioate. Other sulfur and/or phosphorus containing materials which
are not
currently approved for food grade use include: zinc dialkyl dithiophosphate,
zinc
dithiocarbamate, amine dithiocarbamate, and methylene bis dithiocarbamate. Any
of
the above compounds, with HX-1 approval, would be a suitable anti-wear
additive.
[0019] A suitable neutralized alkyl phosphate ester component may include a
component containing a mixture of mono- and di-C4-Cg-alkyl phosphate esters
and/or
polyphosphate esters that have been neutralized with a non-branched chain
amine.
The non-branched chain amines may be selected from tetramethylnonylamines, C>>-
C14 alkylamines, and the like.
[0020] The food grade lubricant may contain from about 0.1 to about 0.5 of the
anti-
wear additive based on a total weight of the lubricant composition. For a food
a ade
lubricant containing the triphenyl phosphorothioate component and the
neutralized
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alkyl phosphate ester wear reducing agents, the anti-wear additive component
of the
composition may include from about 0 wt. % to about 50 wt.% of the triphenyl
phosphorothioate component and from about 35 wt.% to about 100 wt.% of the
neutralized alkyl phosphate ester component.
[0021] A criteria for the anti-wear additive is that the additive be a non-
sludge
promoting antiwear additive. Conventional antiwear additives typically include
a
neutralized dialkyl phosphate that have been neutralized with a C12-C14 t-
alkyl
primary amine. Surprisingly, food grade lubricants containing antiwear
additives that
have not be neutralized with a branched alkyl amine exhibit reduced
sludge/varnish
formation tendencies compared to the same lubricants containing an anti-wear
additive that is neutralized with a C12-C14 t-alkyl primary amine.
ANTI-OXIDANT ADDITIVES
[0022] Antioxidation additives that may be used as a component of the food
grade
lubricant composition include phenolic and amine antioxidants and mixtures
thereof.
[0023] The phenolic antioxidants which may be include, but are not limited to,
food
grade, oil-soluble, sterically hindered phenols and thiophenols. Included
within the
definition of phenolic and thiophenolic antioxidants are sterically hindered
phenolics
such as hindered phenols and bis-phenols, hindered 4,4'-thiobisphenols,
hindered 4-
hydroxy-and 4-thiolbenzoic acid esters and dithio esters, and hindered bis(4-
hydroxy-
and 4-thiolbenzoic acid and dithio acid) alkylene esters. The phenolic moiety
may be
substituted in both positions ortho to the hydroxy or thiol groups with alkyl
groups
which sterically hinder these groups. Such alkyl substituents usually have 3
to 10
carbons, suitably 4 to 8 carbons, with one alkyl group generally being
branched rather
than straight-chain (e.g., t-butyl, t-amyl, etc.).
[0024] The first group of hindered phenolic antioxidants is the single
hindered
phenols. Examples of such compounds include 2,6-bi-tert-butylphenol, 2,6-di-
tert-
butyl-p-cresol, 2,6-di-tert-amyl-p-cresol, and 2-tert-butyl-6-tert-amyl-p-
cresol.
[0025] A second group of hindered phenolic antioxidants is the hindered
bisphenols.
Examples of these compounds include 4,4'-methylene bis(2,6-bi-tert-
butylphenol),
4,4'-dimethylene bis(2,6-di-tert-butyl phenol), 4,4'-trimethylene bis(2,2-di-
tert-amyl
phenol), and 4,4'-trimethylene bis(2,6-di-tert-butyl phenol).
[0026] Another group of hindered phenolic antioxidants is the hindered 4,4'-
thio bis-
phenols. Examples of these compounds include 4,4'-thio bis(2,6-di-sec-butyl
phenol),
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4,4'-thio bis(2-tert-butyl-6-isopropyl phenol), and 4,4'-thio bis(2-methyl-6-t-
butyl
phenol).
[0027] A fourth group of hindered phenolic antioxidants is 4 alkoxy phenols.
Examples of these compounds include butylated hydroxy anisole, butylated
hydroxy
phenetole, and butylated hydroquinone. Any of the above compounds, with HX-1
approval, would be a suitable phenolic antioxidant.
[0028] Butylated hydroxy toluene (BHT) is cost effective, commercially
available,
and is HX-1 approved. Butylated hydroxy toluene may be present in the food
grade
lubricating oil in an amount less than about 1% by weight and most typically
is
present in an amount ranging from about 0.1 to about 0.6% by weight of the
food
grade lubricating oil composition. Likewise, the food grade lubricant
composition
may contain less than 1% by weight of the phenolic antioxidant.
[0029] Suitable food grade, oil-soluble aromatic amine antioxidants are
naphthyl
phenyl amines, alkylated phenyl naphthyl amines, and alkylated diphenyl
amines.
Examples of aromatic amine antioxidants include, but are not limited to, the
napthylamines such as N-phenyl-alpha-naphthylamine, N-p-methyl-phenyl-alpha-
naphthylamine, and the diphenylamines such as di-sec-butyldiphenylamine, di-
isobornyl-di-phenylamine, and dioctyldiphenylamine. Any of the above
compounds,
with HX-1 approval, may be a suitable aromatic amine antioxidant.
[0030] Particularly suitable aromatic amine antioxidants are the alkylated and
dialkylated diphenyl amines, for example, the reaction products of the
alkylation of n-
phenylbenzenamine and 2,4,4 trimethyl pentene. The resultant product of may be
a
mixture of ortho, meta, and para bis(octyl phenyl)amine. Bis(octyl
phenyl)amine may
also be referred to as dioctyl diphenyl amine and is a food grade amine.
Another
suitable food grade diphenyl amine is an octylated, butylated diphenyl amine.
The
aromatic amine may be present in the lubricant composition in an amount of
than
about 1% by weight of the lubricating oil composition. A suitable amount of
alkylated diphenyl amine may range from about 0.05 to about 0.5 wt.% of the
total
weight of the lubricant composition.
[0031] The lubricant composition may typically contain only one antioxidant
additive. However, combinations of the foregoing antioxidant additives may
also be
used. When a combination of antioxidant additives is used, the phenolic and
aromatic
amine antioxidant components may range in ratio by weight from 20:1 to 1:20
although a suitable ratio ranges from 4:1 to 1:1.
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ANTI-RUST ADDITIVES
[0032] The anti-rust additive component may include a combination of food
grade
ionic and non-ionic surface active anti-rust ingredients. The total amount by
weight
of ionic and non-ionic surface active anti-rust additive necessary to impart
the desired
degree of rust resistance may be significantly less than either anti-rust
additive
independently.
[0033] Ionic anti-rust lubricating additives which may be used in the
compositions
described herein may include food grade phosphoric acid, mono and dihexyl
ester
compounds with tetramethyl nonyl amines, and CIo to C18 alkyl amines. Any rust
inhibitor compound with HX-1 approval would be a suitable anti-rust additive.
Likewise, the amine salt of the acid phosphate used as an antiwear additive
may also
be used for its rust inhibiting properties as a anti-rust additive.
100341 Non-ionic anti-rust lubricating additives which may be used in the
compositions described herein may include food grade fatty acids and their
esters
formed from the addition of sorbitan, glycerol, or other polyhydric alcohols,
or
polyalkylene glycols. Other non-ionic anti-rust lubricating additives may
include
food grade ethers from fatty alcohols alkoxylated with alkylene oxides, or
sorbitan
alkoxylated with alkylene oxides, or sorbitan esters alkoxylated with alkylene
oxides.
[0035] Examples of suitable food grade non-ionic anti-rust lubricating
additives
include: sorbitan mono-oleate, ethoxylated vegetable oil, isopropyl oleate,
ethoxylated
fatty acids, ethoxylated fatty alcohols, fatty glyceride esters,
polyoxyethylene sorbitan
mono-oleate, polyoxyethylene sorbitan, glycerol mono-oleate, glycerol di-
oleate,
glycerol mono-stearate, and glycerol di-stearate. Any of the above compounds,
with
HX-1 approval, would be a suitable anti-rust additive.
[0036] The food grade anti-rust additive may comprise less than about 1% by
weight
of the food grade lubricating oil and may comprise from about 0.01 to about
0.3% by
weight of the food grade lubricating oil.
CORROSION INHIBITOR ADDITIVE
[0037] In some embodiments, corrosion inhibitors may constitute another class
of
additives suitable for inclusion in the compositions described herein. Such
compounds include food grade thiazoles, triazoles and thiadiazoles. Examples
of
such compounds include benzotriazole, tolyltriazole, octyltriazole,
decyltriazole,
dodecyltriazole, 2-mercapto benzothiazole, 2,5-dimercapto-1,3,4-thiadiazole, 2-
mercapto-5-hydrocarbylthio-1,3,4-thiadiazoles, 2-mercapto-5- hydrocarbyldithio-
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1,3,4-thiadiazoles, 2,5-bis(hydrocarbylthio)- 1,3,4-thiadiazoles, and 2,5-
bis(hydrocarbyldithio)-1,3,4-thiadiazoles. Suitable compounds include the
1,3,4-
thiadiazoles, a number of which are available as articles of commerce,
combinations
of triazoles such as tolyltriazole with a 1,3,5-thiadiazole such as a 2,5-
bis(alkyldithio)-
1,3,4-thiadiazole, and bis-alkyl-arylalkyl benzotriazole alkylamines such as
N,N-
bis(2-ethyl)ar-methyl-IH-benzotriazole-l-methanamine. The amount of corrosion
inhibitor in the food grade formulations described herein may range from about
0.01
to about 0.5 wt% based on the total weight of the lubricant composition.
ANTIFOAM ADDITIVE
[0038] In some embodiments, a foam inhibitor may form another component
suitable
for use in the food grade compositions. Foam inhibitors may be selected from
silicones, polyacrylates, methacrylates, surfactants, and the like meeting the
HX-1
approval criteria. The amount of antifoam agent in the food grade formulations
described herein may range from about 0.0025 wt% to about 0.01 wt% based on
the
total weight of the food grade lubricant composition.
PERSERVATIVE ADDITIVES
[0039] Suitable food grade preservatives include, but are not limited to
vitamin E (a-
tocopherol) and/or C2-C6 alkyl hydroxyl benzoates such propyl p-hydroxyl
benzoate.
The amount of preservative in the lubricant composition may range from about
0.001
to about 0.1 percent by weight of the total weight of the food grade lubricant
composition.
[0040] Additives used in formulating the compositions described herein may be
blended into the base oil individually or in various sub-combinations.
However, it is
suitable to blend all of the components concurrently using an additive
concentrate
(i.e., additives plus a diluent, such as the base oil). The use of an additive
concentrate
takes advantage of the mutual compatibility afforded by the combination of
ingredients when in the form of an additive concentrate. Also, the use of a
concentrate reduces blending time and lessens the possibility of blending
errors.
[0041] In the following Table 1, the formulations for conventional food grade
lubricant compositions (Samples 1-4) and for food grade lubricant compositions
according to exemplary embodiments described herein (Samples 5-8) are given.
Table 2 compares the results of testing the fluid compositions.
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Table 1
Component Sample I Sample 2 Sample 3 Sample 4
Base Oil 90 90 90 90
Antifoam agent 0.0 0.0 0.02 0.02
Conventional Antiwear 0.20 0.15 0.0 0.0
Agent
Non-sludge forming 0.0 0.0 0.15 0.15
Antiwear Agent
triphenyl phosphorothioate 0.20 0.20 0.20 0.20
vitamin-E 0.01 0.01 0.01 0.01
preservative 0.01 0.01 0.01 0.01
Antioxidant 1 0.20 0.20
Antioxidant 2 0.50 0.50
Corrosion Inhibitor 0.10 0.10 0.10 0.10
Rust Inhibitor 0.05 0.05 0.05 0.05
Table 2
Test Results Sample 1 Sample 2 Sample 3 Sample 4
CCMA Test
sludge wt. (mg/100 ml) 39.11 39.72 9.4 11..68
FZG Scuffing Test --- --- 11 pass 12 pass
4 Ball wear --- --- 0.28 0.27
20 kg/1475 rpm/lhr/ambient
4 Ball wear --- --- 0.47 0.46
20 kg/1475 m/lhr/ambient
[0042] As shown in table 2, the fluid compositions according to the disclosure
(Samples 3-4) provided relatively low sludge results of less than 15 mg/100
mls in the
CCMA test versus a limit of 25 mg/100 mis.
[0043] By comparison, the use of a conventional antiwear agent (Samples 1-2)
exhibited sludge results that were much higher than Samples 3-4 and were over
25
mg/100 mis. Beakers containing Samples 1-2 had much more varnish on them than
the beakers of Samples 3-4. FZG scuffing and wear data for Samples 3-4
indicated
that, even with low sludge, suitable wear protection may be obtained by the
formulations of Samples 3-4 containing the non-sludge forming antiwear agent.
[0044] The foregoing embodiments are susceptible to considerable variation in
its
practice. Accordingly, the embodiments are not intended to be limited to the
specific
exemplifications set forth hereinabove. Rather, the foregoing embodiments are
within
the spirit and scope of the appended claims, including the equivalents thereof
available as a matter of law.
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[0045] The patentees do not intend to dedicate any disclosed embodiments to
the
public, and to the extent any disclosed modifications or alterations may not
literally
fall within the scope of the claims, they are considered to be part hereof
under the
doctrine of equivalents.
