1. A lubricating oil base stock consisting of:
(a) a copolymer of ethylene with one or more alpha olefins, containing not more than 50 wt % ethylene, the copolymer having a number molecular weight from 400 to 10,000 and having a molecular weight distribution <3; and
(b) a hydroprocessed oil having a VI greater than 80, characterized in that the base stock has a VI which is higher than that of the hydroprocessed oil component alone.
2. The base stock of claim 1 wherein the alpha olefin of the copolymer is a C3 to C20 olefin.
3. The base stock of claim 2 wherein the hydroprocessed oil is selected from Group II and Group III oils and Fischer-Tropsch wax isomerates.
4. The base stock of claim 3 wherein the amount of copolymer in the blend ranges from about 1 to about 95 wt %.
5. The base stock of claim 4 wherein the hydroprocessed oil is a Group III oil.
6. The base stock of claim 4 wherein the hydroprocessed oil is a Group II oil.
7. A lubricant base stock consisting of a blend of
(a) from 1 to 95 wt %, based on the blend, of an ethylene alpha olefin copolymer of ethylene with one or more alpha olefins containing not more than 50 wt % ethylene, the copolymer having a number average molecular weight from 400 to 10,000 and having a molecular weight distribution <3; and
(b) from 5 to 99 wt %, based on the blend, a hydroprocessed oil having a VI greater than 80 and selected from Group II and Group III oils and Fischer-Tropsch wax isomerates characterized in that the base stock blend has a VI which is higher than that of the hydroprocessed oil component alone.
8. The base stock of claim 7 wherein the alpha olefin of the copolymer is a C3 to C20 olefin.
9. The base stock of claim 8 wherein the hydroprocessed oil is a Group II oil.
10. The base stock of claim 8 wherein the hydroprocessed oil is a Group III oil.
11. A lubricant which is prepared from:
(i) a lubricant base stock consisting of a blend of:
(a) a copolymer of ethylene with one or more alpha olefins containing not more than 50 wt % ethylene, the copolymer having a number average molecular weight from 400 to 10,000 and a molecular weight distribution <3; and
(b) a hydroprocessed oil having a VI greater than 80 wherein the base stock blend has a VI which is higher than that of the hydroprocessed oil component alone; and
(ii) a lubricant additive package.
12. The lubricant of claim 11 wherein the alpha olefin of the copolymer is a C3 to C20 olefin.
13. The lubricant of claim 12 wherein the hydroprocessed oil is a Group II oil.
14. The lubricant of claim 12 wherein the hydroprocessed oil is a Group III oil.
15. The lubricant of claim 13 or 14 in which the additive package comprises additives selected from the group consisting of viscosity index improvers, corrosion inhibitors, dispersants, oxidation inhibitors, detergents, rust inhibitors, antiwear agents, anti-foaming agents, flow improvers, friction modifiers, and seal swellants.
16. A lubricant which is prepared from:
(i) a lubricant base stock consisting of a blend of:
(a)copolymer of ethylene with one or more alphagolefins containing not more than 50 wt % ethylene, the copolymer having a number average molecular weight from 400 to 10,000 and a molecular weight distribution <3; and
(b) a hydroprocessed oil having a VT greater than 80 wherein the base stock blend has a VI which is higher than that of the hydroprocessed oil component alone;
(ii) a lubricant additive package; and
(iii) a polar co-base stock selected from the group consisting of polyesters, alkylated aromatics and polyalkylene glycols.
17. A method for reducing the loss of viscosity and weight and improving the oxidation stability and low temperature properties of lubricating oil formulations comprising a base oil by employing a base stock consisting of hydroprocessed oil selected from the group consisting of a Group II base oil, a Group III base oil or mixture thereof in combination with a copolymer of ethylene with one or more alpha-olefins containing not more than 50 wt % ethylene, the copolymer having a number average molecular weight from 400 to 10,000 and having a molecular weight distribution <3, wherein the base stock has a VI which is higher than that of the hydroprocessed oil component alone.
The claims below are in addition to those above.
All refrences to claim(s) which appear below refer to the numbering after this setence.
1. A method for determining a phase transition of a substance, comprising:
generating a first measuring signal by measuring a substance-directed heat flow;
generating a measuring signal phase-shifted in relation to the first measuring signal;
determining a difference signal between the first measuring signal and the phase-shifted measuring signal and
determining the phase transition if a property of the difference signal meets a predetermined condition.
2. A method according to claim 1, wherein the generation for the first measuring signal comprises:
varying a temperature of a first surface;
measuring a heat flow from the substance to the first surface and wherein the generation of the phase-shifted signal comprises:
varying a temperature of a second surface, which varying is phase-shifted in relation to the varying of the temperature of the first surface;
measuring a heat flow from the substance to the second surface.
3. A method according to claim 2, wherein the varying of the temperature of at least one of the said surfaces comprises:
heating up the surface by means of a heating element located near the surface;
cooling down the surface by means of a cooling element thermally connected to the surface and located at a distance from the surface.
4. A method according to claim 3, wherein measuring the heat flow comprises:
measuring a heat flow form the surface to the cooling element.
5. A method according to claim 3; wherein the cooling down of the surface comprises:
maintaining at least a part of the cooling element at a constant temperature;
and wherein the heating up of the surface comprises:
varying thermal energy supplied to the surface by the heating element; and
wherein the cooling down and heating up of the surface are carried out at least partially simultaneously.
6. A method according to claim 1, wherein the phase transition is the transition from the gaseous phase to the liquid phase of the substance.
7. A method according to claim 1, wherein the method is used for determining the dew point of a gas.
8. An apparatus for determining a phase transition of a substance, comprising:
a heat flow meter for measuring a substance-directed heat flow, which heat flow meter has a meter output for delivering a first measuring signal constituting a measure for the value of the measured heat flow;
means for generating a phase-shifted measuring signal;
a difference-determining element for determining a difference signal on the basis of the first measuring signal and the phase-shifted measuring signal; and
means for detecting the phase transition on the basis of the difference signal.
9. An apparatus according to claim 8, comprising:
a first heating element;
a first heat flow meter thermally connected to the first heating element, the means for generating a phase-shifted measuring signal comprising:
a second heat flow meter and
a second heating element thermally connected to the second heat flow meter, which first and second heating element are connected to a control circuit which, in use, controls the second heating element in a phase-shifted manner in relation to the first heating element.
10. An apparatus according to claim 8, wherein the means for generating a phase-shifted measuring signal comprise an electronic circuit, which electronic circuit at least comprises:
a phase-shifting element connected to an output of the heat flow meter;
a combining element having
a first input connected to an output of the phase-shifting element and
a second input connected to the output of the heat flow meter,
an output to which a difference signal of the signals presented to the inputs is provided, wherein one of the inputs is a negative input and another of the inputs in a positive input;
and which circuit further comprises:
a detection element connected to the output of the combining element for detecting a predetermined property of the difference signal.