GB2535179A

GB2535179A - Formulation and method

Info

Publication number: GB2535179A
Application number: GB1502247.8A
Authority: GB
Inventors: Jonathan Maconachie Andrew; Meadows Mark
Original assignee: JOHN HOGG TECHNICAL SOLUTIONS Ltd
Current assignee: JOHN HOGG TECHNICAL SOLUTIONS Ltd
Priority date: 2015-02-11
Filing date: 2015-02-11
Publication date: 2016-08-17
Also published as: GB201502247D0

Abstract

Dye formulations for marking liquid hydrocarbon fuels, lubricants and oils A marker dye formulation for marking liquid hydrocarbon fuels, lubricants and oils wherein the formulation comprises: one or more azo dye(s) in a total amount of formula 1 to 60 weight%; one or more hydrocarbon solvents in a total amount of 2 to 98 weight %; and one or more co-solvents of formula (I) in a total amount of formula 1 to 20 weight % wherein in formula 1: X is H, methyl, ethyl or propyl; R1 is H, optionally substituted C1-6alkyl, or optionally substituted aryl; R2 is H, optionally substituted C1-6alkyl, or optionally substituted aryl; and n is 1 to 4. Preferably the co-solvent is selected from dipropylene glycol monomethyl ether, diethylene glycol monobutyl ether and diethylene glycol monomethyl ether. Preferably the azo dye comprises one or more dyes selected from the group consisting of Solvent Yellow 124, Solvent Red19 and Solvent Orange 2. The hydrocarbon solvent is preferably a naphtha aromatic solvent selected from the group consisting of C20 type SolvessoRTM 150, ShellsolRTM A150, SolvarexRTM 10, C28 type SolvessoRTM 200. A method of marking a liquid hydrocarbon fuels, lubricants or oils with the dye formulation is also outlined. Preferably the hydrocarbon fuels, lubricants and oils are selected from the group consisting of kerosene, gasoline, jet fuel and diesel fuel, heating oil, lubricating oil or brake fluid.

Description

Intellectual Property Office Application No. GII1502247.8 RTM Date:5 November 2015 The following terms are registered trade marks and should be read as such wherever they occur in this document: Solvesso Shellsol Solvarex Intellectual Property Office is an operating name of the Patent Office www.gov.uk /ipo

FORMULATION AND METHOD

The present invention relates to marker dye formulations and to the use of same for marking liquid hydrocarbon fuels, lubricants and oils.

Dyes are defined as organic compounds which possess colour. That is, dyes absorb light in the visible spectrum (400-700 nm) and comprise at least one chromophore (colour-bearing group). In addition, dyes possess a conjugated system, and exhibit resonance of electrons. If one of these features is absent from the molecular structure of the dye the colour is lost.

It is known to mark hydrocarbon fuels and lubricants with various kinds of chemical marker dyes for the purposes of authentication and fraud prevention. A variety of compounds have been used for this purpose, and there are numerous techniques for detecting the markers such as for example, absorption spectroscopy and mass spectrometry.

Dyes are typically added to hydrocarbon fuels as markers at levels of from 0.1 to 20 mg/litre. When preparing marked fuels and lubricants, it is desirable to first prepare a concentrated, stable liquid formulation of the dye which may then be added to the desired fuel or lubricant as required.

Current concentrated dye formulations used for marking fuels suffer from several disadvantages. In particular, some dye formulations are prone to precipitation when prepared as concentrated formulations (also known as concentrates). In addition, impurities present in the dye concentrates, or oxidation products of the dyes produced during storage are prone to precipitation during storage. This problem is exacerbated by long periods of storage, and especially storage of the dye at extremes of temperature.

The addition of concentrated dye formulations to hydrocarbon fuels, lubricants or oils stored in tanks and tankers, leads to a build-up over time of the levels of precipitates or impurities. This build-up of precipitates or impurities gradually leads to blocked fuel lines and filters in the storage tanks and tankers. Removal of the impurities and precipitates from the tanks and tankers and the replacement of filters and fuel lines is costly and time consuming, leading to delays in processing and fuel transportation.

It has been postulated to add further components to fuels and lubricants in an attempt to stabilise concentrated dye formulations and thereby alleviate the problems associated with impurities and precipitates.

For example, it is known to add various phenols (particularly nonyl phenol) to fuels and lubricants to try and overcome this problem. However, the use of phenols as solvents poses additional problems, not least of all because such compounds are toxic, corrosive and environmentally damaging.

The aim of the present invention is therefore to find an alternative means for solubilising and stabilising marker dye formulations and dye concentrates, by avoiding impurity and precipitation problems when the components of the dye formulation are formulated.

In accordance with a first aspect of the present invention there is provided: a marker dye formulation, suitable for use in marking liquid hydrocarbon fuels, lubricants and oils wherein the formulation comprises: one or more azo dye(s) in a total amount of from 1 to 60 weight %; one or more hydrocarbon solvent(s) in a total amount of 2 to 98 weight %; and one or more co-solvent(s) of Formula 1 present in a total amount of from 1 to 20 weight %

X

0 CH2 CH I 0 R2 Formula 1 wherein in Formula 1: X is H, methyl, ethyl or propyl; RI is H, optionally substituted C1_6 alkyl or optionally substituted aryl; R2 is H, optionally substituted C1_6 alkyl or optionally substituted aryl; and n is 1 to 4.

The advantages of the present invention are that the marker dye formulation possesses improved stabilising properties when used for marking hydrocarbon fuels, lubricants and oils which overcomes, or at least mitigates the problems associated with prior art marker dye formulations such as the build-up of impurities and oxidation products arising from the dye during storage.

That is, the inventors have found that certain dye concentrates may be formulated in accordance with the present invention and are useful for marking liquid hydrocarbons such as but not limited to: diesel, gasoline, kerosene, jet fuel, heating oil and lubricants, as the marker dye formulations of the present invention do not lead to a build-up of impurities and oxidation products in filters and fuel lines.

Most importantly, the inventors have found a novel marker dye formulation which has improved stability to precipitation and/or oxidation of the azo dye, thereby leading to reduced levels of impurities or oxidation products in the formulation and increased liquid concentrate stability.

Co-solvents.

Co-solvents for use in the marker dye formulation according to the present invention are miscible with hydrocarbon fuels, oils or lubricants, and also sufficiently polar to solubilise and stabilise the azo marker dye.

In the marker dye formulation of the present invention the co-solvent preferably comprises one or more glycol ether solvents selected from the group consisting of: propylene glycol methyl ether, dipropylene glycol methyl ether, tripropylene glycol methyl ether, propylene glycol n-propyl ether, di-propylene glycol n-propyl ether, propylene glycol n-butyl ether, di-propylene glycol n-butyl ether, tri-propylene glycol n-butyl ether, propylene glycol phenyl ether, dipropylene glycol dimethyl ether, diethylene glycol ethyl ether, diethylene glycol methyl ether, diethylene glycol n-butyl ether, diethylene glycol hexyl ether, ethylene glycol propyl ether, ethylene glycol n-butyl ether, ethylene glycol hexyl ether, triethylene glycol methyl ether, triethylene glycol ethyl ether, triethylene glycol n-butyl ether, ethylene glycol phenyl ether and ethylene glycol n-butyl ether.

The co-solvent is preferably present in the marker dye formulation in an amount of 2 to 18 weight %. More preferably the co-solvent is present in the marker dye formulation in an amount of from 3 to 16 weight %. Even more preferably the co-solvent is present in the marker dye formulation in an amount of from 5 to 15 weight %. Most preferably the co-solvent is present in the marker dye formulation in an amount of from 3 to 8 weight %, or even 4 to 6 weight %.

It is preferred in the marker dye formulation according to the present invention that for the co-solvent of Formula 1: R1 is optionally substituted C1_6 alkyl or optionally substituted aryl; R2 is H, Xis H or methyl; and n is 1 or 2.

More preferably, it is preferred that in the dye formulation according to the present invention that for the co-solvent of Formula 1: R1 is methyl or butyl; X is H or methyl; R2 is H or methyl; and n is 1 or 2.

That is, it is most preferred that in the marker dye formulation according to the present invention the co-solvent comprises dipropyl glycol methyl ether and/or diethylene glycol n-butyl ether.

A combination of co-solvents may be used in the marker dye formulation according to the present invention. Alternatively, single co-solvents may be used in the marker dye formulations.

When two co-solvents are used in the marker dye formulation of the present invention such as dipropyl glycol methyl ether and diethylene glycol n-butyl ether, it is preferred that the co-solvents are present in a ratio of 1: 1. It is however more preferred that only a single co-solvent is used in the marker dye formulation of the present invention.

Azo dyes.

The term azo refers to a compound with at least one azo group (-N=N-). It is preferred that the azo compounds used in the dye formulation of the present invention are mono-azo compounds.

In the marker dye formulation according to the present invention, the one or more azo dye is/are preferably present in an amount of from 2.5 to 60 weight %. More preferably in the marker dye formulation according to the present invention, the azo dye is/are preferably present in an amount from 20 to 35 weight %.

It is also preferred that the azo dyes of the present invention are hydrophobic.

The azo-dyes used in the dye formulation of the present invention may be blue, red, yellow, orange, black or green. However, it is preferred that the azo compounds used in the marker dye formulation according to the present invention are red, orange or yellow dyes, and that these dyes are used either alone or in combination.

Suitable commercial red, yellow and orange dyes for use in accordance with the present invention are listed below using their colour index number. The dyes include but are not limited to: Solvent Yellow 2, Solvent Yellow 5, Solvent Yellow 13, Solvent Yellow 14, Solvent Yellow 15, Solvent Yellow 16, Solvent Yellow 18, Solvent Yellow 19, Solvent Yellow 21, solvent yellow 24, Solvent Yellow 33, Solvent Yellow 43, Solvent Yellow 44, Solvent Yellow 51, Solvent Yellow 56, Solvent Yellow 62, Solvent Yellow 72, Solvent Yellow 77, Solvent Yellow 82, Solvent Yellow 90, Solvent Yellow 93, Solvent Yellow 98, Solvent Yellow 109, Solvent Yellow 114, Solvent Yellow 124, Solvent Yellow 145, Solvent Yellow 163, Solvent Yellow 167, Solvent Yellow 176, Solvent Orange 2, Solvent Red 1, Solvent Red 2, Solvent Red 3, Solvent Red 4, Solvent Red 8, Solvent Red 13, Solvent Red 18, Solvent Red 19, Solvent Red 23, Solvent Red 24, Solvent Red 25, Solvent Red 26, Solvent Red 27, Solvent Red 30, Solvent Red 32, Solvent Red 49, Solvent Red 52, Solvent Red 79, Solvent Red 89, Solvent Red 109, Solvent Red 111, Solvent Red 119, Solvent Red 122, Solvent Red 127, Solvent Red 130, Solvent Red 132, Solvent Red 135, Solvent Red 146, Solvent Red 160, Solvent Red 164, Solvent Red 168, Solvent Red 169, Solvent Red 172, Solvent Red 175, Solvent Red 179, Solvent Red 197, Solvent Red 207, Solvent Red 215, Solvent Red 218, Solvent Red 412, Sudan Red 412, Sudan Red 462.

Preferred commercially available yellow, orange and red dyes used in the formulation of the present invention are however selected from the group consisting of: Solvent Red 23 -2-Naphthalenol, 14[4-(phenylazo)phenyl]azob (CAS number 85-85-9). CAS Register number is a registered trademark of the American Chemical Society.

Solvent Red 24 -1-(2-methyl-4-(2-methylphenyldiazenyl) phenyl) azonapthalen-2-ol, (CAS number 85-83-6)

N /7

Solvent Red 25, 1-[[3-methy1-4-[(3-methylphenypazo]phenyflazo]-2-naphthol, (CAS number 3176-79-2) e HO.

Solvent Red 26 (C.I.26120) is a purplish red synthetic azo dye, soluble in oils and insoluble in water (CAS number 4477-49-6).

OH

Solvent and 27 -1-(2,5-dimethy1-4-(2-5-dimethylphenyl) phenyldiazenyl) azonapthalen-2-ol, (CAS number 1320-06-5) cH3 HO <7--7\ N '=-11 CH3 Solvent Red 164 -1-[[2,5-dimethy1-4-[(2-methylphenyl)azoLphenyl]azo]-2-naphthol (CAS number 71819-51-7) r^ <'* * C, Solvent Red 215 (Sudan Red 412) -(No CAS number or colour index number available).

Available from BASF Aktiengesellschaft, Retort Chemicals Private Ltd and J.K.Colors.

Solvent Red 19, also known as Sudan Red 462 -N-Ethyl-1-((4-phenyldiazenyl)phenyl)diazenyl)naphthalen-2-amine, (CAS number 6368-725) Solvent Yellow 124 -N-Ethyl-N-[2-0-(2-methylpropoxy)ethoxidethyl]-4-phenyldiazenylaniline, CAS (Chemical abstracts service registry number) 34432-92-3).

Solvent Yellow changes color to red in acidic pH. It may be easily detected in hydrocarbon fuels at levels as low as 0.3 ppm by extraction with diluted hydrochloric acid, allowing detection in for example red motor diesel in amounts as low as 2 to 3%.

As the amount of dye such as Solvent Yellow 124 added to a fuel is known, by measuring its content for example in fuel it is possible to calculate for example how much low-taxed fuel has been added to a legal fuel.

Solvent Orange 2 -1-((2-methylphenyhazoF 2-Naphalenol (CAS number 2646-17-5) In relation to the present invention it is particularly preferred that the one or more azo dyes are selected from the group consisting of: Solvent Yellow 124, Solvent Orange 2 and Solvent Red 19.

When two dyes are used in combination such as Solvent Yellow 124 and Solvent Red 19, it is preferred that these dyes are used in the formulation in a ratio of 1:4 to 2:1. More preferably these two dyes are present in the formulation in a ratio of 1:1 to 1:2.

When Solvent Yellow 124 and Solvent Orange 2 are used as the dyes in the formulation it is preferred that these dyes are used in a ratio of 1:4 to 2:1. More preferably these two dyes are present in the formulation in a ratio of 1:1 to 1:2. Even more preferably these two dyes are mixed in a ratio of 1:10 to 1:1 or in a ratio of 1:10 to 1:5.

When solvent Orange 2 and Solvent Red 19 are used in the formulation according to the present invention it is preferred that these two dyes are present in a ratio of 1: 4 to 2: 1. More preferably these two dyes are present in the formulation in a ratio of 1:1 to 1:2. Even more preferably these two dyes are mixed in a ratio of ratio of 1:10 to 1:1 or in a ratio of 1:10 to 1:5.

When all three azo dyes (i.e. Solvent Yellow 124, Solvent Orange 2 and Solvent Red 19) are used in combination in the formulation of the present invention it is preferred that the azo dyes are present in a ratio of 1:3:5 to 1:10:20 (Orange: Red: Yellow). More preferably when all three azo dyes are used in combination in the formulation of the present invention it is preferred that the azo dyes are present in a ratio of 1:7:10 (Orange: Red: Yellow).

In the present invention it is preferred that Solvent Orange 2, Solvent Red 19 and Solvent Yellow 124 are used in combination in the formulation.

Hydrocarbon solvents The hydrocarbon solvents used in the marker dye formulation according to the present invention are commercially available naphtha aromatic solvents, for example SolvessoTM available from Exxon Mobile.

SolvessoTM aromatic fluids are heavy aromatic grade solvents with high solvency and controlled evaporation characteristics that make them versatile performers in many industrial and agricultural applications. The aromatic content of SolvessoT" fluids is typically around 99% or higher.

Examples of hydrocarbon solvents which may be used in relation to the present invention include but are not limited to: C20 Type SolvessoTM 150 and C28 Type SolvessoTM 200 available from Exxon Mobile; Shellsol® A150 available from Shell; and Solvarex® 10 available from Total. These solvents may be either used singly or in combination.

The one or more hydrocarbon solvent(s) used in the dye formulation according to the present invention is/are present in an amount of from 2 to 98 weight %. The amount of hydrocarbon solvent present will depend upon the amount of azo dye and the amount of co-solvent used in the formulation. It is usual however to have hydrocarbon solvent present in the marker dye formulation in an amount of at least 20 weight %.

As indicated above the marker dye formulations of the present invention are useful for marking liquid hydrocarbons such as but not limited to: diesel, gasoline, kerosene, jet fuel, heating oil and lubricants due to the improved stability to precipitation and/or oxidation of the azo dye present in the formulations.

According to a second aspect of the present invention there is provided a method of marking a liquid hydrocarbon fuel, lubricant or oil, said method comprising adding to the liquid hydrocarbon fuel, lubricant or oil a marker dye formulation according to the first aspect of the present invention wherein the formulation in added to the fuel lubricant or oil in an amount of from 1 to 100 ppm.

In relation to the second aspect of the present invention the marker dye formulation is added to the liquid hydrocarbon fuel, lubricant or oil in an amount of at least 10 ppm.

More preferably, the marker dye formulation is added to the liquid hydrocarbon fuel, lubricant or oil in an amount of at least 2Oppm. Most preferably, the marker dye formulation is added to the liquid hydrocarbon fuel, lubricant or oil in an amount of at least 4Oppm.

In accordance with the second aspect of the present invention all the features of the marker dye formulation according to the first aspect of the present invention also apply to the second aspect of the present invention.

The marker dye formulation is prepared as a concentrate and the concentrate is then supplied as required to distributors wishing to mark fuel, oils or lubricants.

The dye marker formulation of the present invention is ideally suited for marking liquid hydrocarbon fuels, lubricants or oils.

According to a third aspect of the present invention there is provided the use of a marker dye formulation according to the first aspect of the present invention for use in marking liquid hydrocarbon fuels, lubricants or oils selected from the group consisting of: gasoline, diesel fuel, kerosene, jet fuel and heating oil, lubricating oil and brake fluid.

In accordance with the third aspect of the present invention all the features of the marker dye formulation according to the first aspect of the present invention also apply to the third aspect of the present invention.

Dye Formulations In relation to the formulations of the present invention, percentages are weight percentages, unless otherwise indicated. Concentrations in parts per million ("ppm") are calculated on a weight/volume basis.

The term "liquid hydrocarbon fuels" refers to products having a predominantly hydrocarbon composition that are derived from petroleum such as lubricating oil, brake fluid, hydraulic fluid, gasoline, diesel fuel, kerosene, jet fuel and heating oil.

In relation to Formula 1: an "alkyl" group is an aliphatic or alicyclic hydrocarbyl group having from one to eight carbon atoms in a linear, branched or cyclic arrangement; when substituted, alkyl groups may be substituted with one or more halo, hydroxy or alkoxy groups; an alkoxy group may in turn be substituted by one or more halo substituents.

It is however preferred that in relation to the present invention the alkyl groups in Formula 1 have no halo or alkoxy substituents.

An "aryl" group is a substituent derived from an aromatic hydrocarbon compound. An aryl group may have a total of from six to twenty ring atoms, and may have one or more rings which are separate or fused.

It is also preferred that in relation to the present invention the aryl groups do not contain halogen atoms.

The marker dye formulation of the present invention may also include: stabilisers, biocides, rheology modifiers or any other functional additives.

The invention will now be illustrated further by the following non-limiting examples and drawings in which all parts and percentages are by weight unless otherwise stated.

Figure 1 -is a photograph of a filter paper following filtration of a marker dye formulation comprising solvent yellow 124 and no co-solvent after storage for 1 month at 23 °C.

Figure 2 -is a photograph of a filter paper following filtration of a marker dye formulation comprising 1% co-solvent consisting of solvent yellow 124 and propylene glycol monomethyl ether after storage for 1 month at 23 °C.

Figure 3 -is a photograph of a filter paper following filtration of a marker dye formulation comprising 5% co-solvent consisting of solvent yellow 124 and dipropylene glycol monomethyl ether after storage for 1 month at 23 °C.

Examples

Example 1 -Comparative example, no co-solvent present.

parts by weight of a 65 % w/w solution of Solvent Yellow 124 in SolvessoTM 150 was stirred with 75 parts by weight SolvessoTm 150 to prepare a formulation.

Example 2

parts by weight of dipropylene glycol monomethyl ether was added to 25 parts by weight of a 65 % w/w solution of Solvent Yellow 124 in SolvessoTM 150. The mixture was stirred and 70 parts by weight of SolvessoTm 150 to prepare a formulation.

Example 3

parts by weight of diethylene glycol monobutyl ether was added to 25 parts by weight of a 65 % w/w solution of Solvent Yellow 124 in SolvessoTM 150. The mixture was stirred and 70 parts of SolvessoTM 150 was added to prepare a formulation.

Example 4 -Comparative example, with no co-solvent present.

parts by weight of Solvent Yellow 124 and Solvent Red 19 in a ratio of 23: 7, prepared as a 65 % w/w solution in SolvessoTM 150 was stirred with 75 parts by weight of SolvessoTM 150 to prepare a formulation.

Example 5

parts by weight of dipropylene glycol monomethyl ether was added to 25 parts by weight of Solvent Yellow 124 and Solvent Red 19 in a ratio of 23: 7, prepared as a 65 % w/w solution in SolvessoTM 150. The mixture was stirred and 70 parts by weight SolvessoTM 150 was added to prepare a formulation.

Example 6 -Stability investigation.

Each of the dye formulations prepared in Examples 1 to 5 were filtered through a separately weighed white filter paper (Whatman nylon filter, 0.45pm, 47mm diameter). Each filter paper was then examined and any insoluble materials remaining on the filter papers weighed.

The results obtained from Example 6 are provided in Table 1.

Table 1 -provides details on the effect of the co-solvents according to the present invention on the stability of the formulations in Examples 1 to 5.

Example Co-solvent Dye (all dye at 15 % Insoluble % mass/mass) material after initial filtering 1 None Solvent Yellow 124 0.064% 2 5% Dipropylene glycol Solvent Yellow 124 0.000% monomethyl ether 3 5% Diethylene glycol Solvent Yellow 124 0.000% monobutyl ether 4 None Solvent Yellow 0.058% 124/Solvent Red 19 (23:7) 5% Diethylene glycol Solvent Yellow 124/ 0.000% monomethyl ether Solvent Red 19 (23:7) It can be seen from the results in Table 1 that Examples 1 and 4 prepared in the absence of co-solvent left insoluble material on the filter paper after the initial filtering whereas Examples 2, 3 and 5 prepared with co-solvent left no insoluble material on the filter paper.

Example 7

To confirm the findings of Examples 1 and 2, four samples of the formulation described in Example 1 were prepared using four different batches of Solvent Yellow 124, and four samples of the formulation described in Example 2 were prepared using the same four batches of Solvent Yellow 124 in combination with dipropylene glycol methyl ether 5% as co-solvent. 10g of each of the 8 samples were filtered and the levels of insoluble material in the liquid formulations were determined using the following quantitative method which follows ASTM D2276 (IP 216) and the results recorded as described below. ASTM D2276 (IP216) is a standard quality control method used to determine the levels of insoluble material in fluid the application of which is described below.

Quantitative Determination of Insoluble Material.

ASTM D2276 is a quantitative determination of toluene insoluble material. The results obtained are expressed as percentage weight insoluble, and the method is applicable to the determination of insoluble material in liquid organic samples in the range 0 to 2% weight/weight.

Apparatus Reagents Balance (accurate to 4 decimal places) 100m1 Beaker Magnetic Stirring Plate and Stirrer Bar Watch-glasses Membrane Filters-47mm diameter, nominal pore size 0.45pm.

Sartorius filter unit (Sintered glass membrane holder, funnel, clamp, flask with side arm) Vacuum pump and tubing Drying Oven Toluene G.P.R Iso-octane Method A sample of test formulation was mixed with toluene and stirred at room temperature until homogenous. The solution was then filtered through a dried and pre-weighed 45-micron membrane test filter and control filter, allowing the calculation of the percentage weight of insoluble material present.

In a fume cabinet, all components of the filtration apparatus, beakers and stirring bars were first rinsed with toluene to ensure that there was no particulate contamination and to minimise apparatus contamination from airborne dust. The test and control membrane filters were weighed accurately and placed in a filtration apparatus connected to a vacuum.

lOg of the dye formulation under test was placed into a 100m1 beaker and 50m1 of toluene added along with a clean magnetic stirrer. The beaker was covered with a clean watch glass and the mixture stirred without heating for 5 minutes with no splashing.

A first portion of the dye solution was then poured into the filter funnel and a vacuum applied to draw the liquid through the membrane filters. Additional solution was poured into the filter funnel until the entire sample had been subject to filtration under vacuum.

The beaker was then rinsed with 4 x 10mIs of 1:1 toluene: isooctane mixture, each time placing the washings in the filter funnel to collect any material in the washings. The filter funnel was then also rinsed with a 1:1 toluene: isooctane solution.

Once the filtration under vacuum was complete the membrane filters were then placed individually onto clean watch-glasses and covered with cleaned crucibles, labelled and placed in a preheated oven at 40 °C until dry. The dried membrane filters were then weighed accurately.

The percentage of insoluble material in the samples was calculated using equation 1 below: Equation 1: % Insoluble material = [(W2-W1) -(W4-W3)]/W5 x 100 wherein W1 = Initial weight of the test membrane filter W2 = Final weight of the test membrane filter W3 = Initial weight of the control membrane filter W4 = Final weight of the control membrane filter W5 = Weight of sample under test The percentage of insoluble material (weight/weight) to the nearest 0.01 percent filtered from each sample was measured and recorded and the results are provided in Table 2. The increased levels of insoluble material in each of the four samples prepared without co-solvent is clearly evident from samples 1 to 4 compared to samples 5 to 8 prepared with dipropylene glycol methyl ether 5%, as co-solvent. The advantage of using a co-solvent with these particular fuel markers is therefore evident.

TABLE 2

Sample Weight of sample Weight of sample filter % insoluble material filter pre-filtration * ost filtration retained on filter 1 0.1001 0.1130 0.0368 2 0.0957 0.1107 0.0444 3 0.1013 0.1223 0.0708 4 0.0958 0.1101 0.0400 0.1015 0.1069 0.0068 6 0.0949 0.1043 0.0200 7 0.1021 0.1099 0.0072 8 0.1022 0.1082 0.0060 A comparison of the results of samples 1 and 5; 2 and 6; 3 and 7; and 4 and 8 in Table 2 shows the effect of dipropylene glycol methyl ether when present in the formulation.

Photographs of filter papers were taken following the filtration of a marker dye formulation in the absence or presence of a co-solvent through the filter paper and are depicted in Figures 1, 2 and 3.

Figure 1 is a picture of a filter paper through which a marker dye formulation comprising Solvent Yellow 124 (16 weight %) and no co-solvent after storage for 1 month at 23 °C has been filtered as a control.

Figure 2 is a picture of filter paper through which a marker dye formulation comprising Solvent Yellow 124 (16 weight %) and propylene glycol monomethyl ether solvent (1 weight %) after storage for 1 month at 23 °C has been filtered.

Figure 3 is a picture of filter paper though which a marker dye formulation comprising Solvent Yellow 124 (16 weight %) and dipropylene glycol monomethyl ether co-solvent (5 weight %) after storage for 1 month at 23 °C has been filtered.

From Figures 1, 2 and 3 it can be seen that for the filter paper in Figure 1 in which no co-solvent was present in the marker dye formulation, extensive impurities are visible in the centre and creases of the filter paper.

In contrast for the filter paper in Figure 2 in which co-solvent dipropylene glycol monomethyl ether at a concentration of 1 weight % was present in the marker dye formulation, minimal impurities are visible in the centre and creases of the filter paper. For the filter paper in Figure 3 in which co-solvent dipropylene glycol monomethyl ether at a concentration of 5 weight % was present in the marker dye formulation, no impurities are visible in the centre and creases of the filter paper.

Claims

Claims 1. A marker dye formulation, suitable for use in marking liquid hydrocarbon fuel, lubricants and oils wherein the formulation comprises: one or more azo dye(s) in a total amount of from 1 to 60 weight %; one or more hydrocarbon solvent(s) in a total amount of 2 to 98 weight %; and one or more co-solvent(s) of Formula 1 present in a total amount of from 1 to 20 weight %XFormula 1 wherein in Formula 1: X is H, methyl, ethyl or propyl; RI is H, optionally substituted C1_6 alkyl, or optionally substituted aryl; R2 is H, optionally substituted C1_6 alkyl, or optionally substituted aryl; and n is 1 to 4.
2. A dye formulation according to claims 1 wherein the co-solvent is present in an amount of 2 to 18 weight %, more preferably in an amount of from 3 to 16 weight %.
3. A dye formulation according to claim 1 or 2 wherein the co-solvent is selected from the group consisting of: propylene glycol methyl ether, dipropylene glycol methyl ether, tripropylene glycol methyl ether, propylene glycol n-propyl ether, di-propylene glycol n-propyl ether, propylene glycol n-butyl ether, di-propylene glycol n-butyl ether, tri-propylene glycol n-butyl ether, propylene glycol phenyl ether, dipropylene glycol dimethyl ether, diethylene glycol ethyl ether, diethylene glycol methyl ether, diethylene glycol n-butyl ether, diethylene glycol hexyl ether, ethylene glycol propyl ether, ethylene glycol n-butyl ether; ethylene glycol hexyl ether, triethylene glycol methyl ether, triethylene glycol ethyl ether, triethylene glycol n-butyl ether, ethylene glycol phenyl ether, ethylene glycol n-butyl ether.
4. A dye formulation according to any of claims 1 to 3 wherein for the co-solvent of Formula 1: is optionally substituted C1_5 alkyl or optionally substituted aryl; R2 is H, Xis H or methyl; and n is 1 or 2.
5. A dye formulation according to any of claims 1 to 3 wherein for the co-solvent of Formula 1: R1 is methyl or butyl; X is H or methyl; R2 is H or methyl; and n is 1 or 2.
6. A dye formulation according to any of claims 1 to 3 wherein the co-solvent comprises dipropyl glycol methyl ether and/or diethylene glycol n-butyl ether.
7. A dye formulation according to any preceding claim wherein the azo dye is present in an amount from 2.5 to 60 weight %, more preferably from 20 to 35 weight %.
8. A dye formulation according to claim 7 wherein the azo dye is a yellow dye and/or a red dye and/or an orange dye.
9. A dye formulation according to claims 7 or 8 wherein the azo dye comprises one or more dyes selected from the group consisting of: Solvent Yellow 124, Solvent Red 19, and Solvent Orange 2.
10. A dye formulation according to claim 9 wherein the azo dye comprises: Solvent Yellow 124 and Solvent Orange 2.
11. A dye formulation according to claim 9 wherein the azo dye comprises: Solvent Red 19 and Solvent Orange 2.
12. A dye formulation according to claim 9 wherein the azo dye comprises: Solvent Yellow 124 and Solvent Red 19.
13. A dye formulation according to claim 9 wherein the azo dyes comprise Solvent Yellow 124 and Solvent 19 in a ratio of 1: 4 to 2: 1.
14. A dye formulation according to claim 9 wherein the azo dyes comprise Solvent Yellow and Solvent orange 2 in a ratio of 1: 4 to 2: 1.
15. A dye formulation according to claim 9 wherein the azo dyes comprise Solvent Red 19 and Solvent Orange 2 in a ratio of 1: 4 to 2: 1.
16. A dye formulation according to any of claims 1 to 15 wherein the hydrocarbon solvents are naphtha aromatic solvents.
17. A dye formulation according to claim 16 wherein the hydrocarbon solvents are selected from the group consisting of: C20 Type Solvessow 150, Shellsol® A150, Solvarex® 10, C28 Type SolvessoTM 200.
18. A method of marking a liquid hydrocarbon fuel, lubricant or oil, said method comprising adding to the hydrocarbon fuel, lubricant or oil a marker dye formulation according to any of claims 1 to 17 wherein: the marker dye formulation in added to the liquid hydrocarbon fuel, lubricant or oil in an amount of from 1 to 100 ppm.
19. A method according to claim 18 wherein the marker dye formulation is added to the liquid hydrocarbon fuel, lubricant or oil in an amount of at least 10 ppm.
20. Use of a marker dye formulation according to any of claims 1 to 17 for use in marking liquid hydrocarbon fuels, lubricants or oils selected from the group consisting of: gasoline, diesel fuel, kerosene, jet fuel and heating oil, lubricating oil and brake fluid.