USE OF AN ALKYL METHACRYLATE POLYMER TO REDUCE PARTICULATE EMISSIONS

Abstract

The present invention relates to the use of lubricant composition containing a base oil and at least one alkyl methacrylate polymer, to reduce engine particulate emissions.

Claims

1. A method for reducing the emission of particles in an engine said method comprising the use of a lubricating composition comprising a base oil and at least one alkyl methacrylate polymer.

2. The method according to claim 1, wherein the alkyl methacrylate polymer is a comb polymer, the pendant chains of which comprise at least 50 carbon atoms, said alkyl methacrylate polymer being chosen from copolymers of at least one polyolefin and at least one poly(alkyl)methacrylate; copolymers of at least one polyolefin and at least one poly(alkyl)acrylate.

3. The method according to claim 1, wherein the alkyl methacrylate polymer is a comb polymer the pendant chains of which are obtained by polymerization or copolymerization of olefins. ##STR00008##

4. The method according to claim 1, wherein the alkyl methacrylate polymer is prepared by copolymerization: of an olefinic monomer with the formula (C2) ##STR00009## wherein Q.sup.3 represents an either linear or branched C.sub.2-C.sub.8-alkyl group; a C.sub.3-C.sub.8-cycloalkyl group; a C.sub.6-C.sub.10-aryl group; Q.sup.4 represents a hydrogen atom or a methyl group; L.sup.1 represents a 1,4-addition residue of butadiene; a 1,4-addition residue of butadiene substituted with at least one C.sub.1-C.sub.6 alkyl group; a vinyl addition residue of styrene; a vinyl addition residue of styrene substituted with at least one C.sub.1-C.sub.6-alkyl group; L.sup.2 represents a vinyl addition residue of butadiene; a vinyl addition residue of butadiene substituted with a C.sub.1-C.sub.6-alkyl group; a vinyl addition residue of styrene; a vinyl addition residue to styrene substituted with at least one C.sub.1-C.sub.6-alkyl group; k and j independently represent 0 or an integer ranging from 1 to 3.000, and the sum (k+j) is equal to an integer ranging from 7 to 3,000; and of an acrylic alkyl ester or methacrylic alkyl ester monomer of formula (C3) ##STR00010## wherein: Q.sup.5 represents a hydrogen atom or a methyl group Q.sup.6 represents an either linear or branched C.sub.1-C.sub.26 alkyl group.

5. The method according to claim 1, wherein the alkyl methacrylate polymer is prepared by copolymerization: of an olefinic monomer with the formula (C4) ##STR00011## wherein: Q.sup.7 represents a C.sub.1-C.sub.6-alkyl group; a C.sub.6-aryl group; Q.sup.8 represents a hydrogen atom or a methyl group; Q.sup.9, Q.sup.10 and Q.sup.11 independently represent a hydrogen atom or a C.sub.1-C.sub.18-alkyl group; x, y and z independently represent 0 or an integer ranging from 1 to 3,000 and the sum (x+y+z) is equal to an integer ranging from 7 to 3,000; and of an acrylic alkyl ester or methacrylic alkyl ester monomer with the formula (C3) ##STR00012## wherein: Q.sup.5 represents a hydrogen atom or a methyl group; Q.sup.6 represents an either linear or branched C.sub.1-C.sub.2-alkyl group.

6. The method according to any of claim 1, wherein the alkyl methacrylate polymer is used in an amount of 0.1 to 15% by weight with respect to the total weight of the lubricating composition.

7. A method for reducing the emission of particles in an engine lubricated by a lubricating composition, said method comprising the addition of an alkyl methacrylate polymer to said lubricating composition.

8. The method according to claim 1, wherein the particles have a size less than or equal to 23 nm.

9. The method according to claim 1, wherein the reduction of particle emissions relates to urban, peri-urban and road-type cycles as defined by the WLTC and/or the whole WLTC.

10. The method according to claim 3, wherein the pendant chains of the comb polymer are obtained by polymerization or copolymnerization of olefins comprising from 8 to 17 carbon atoms and chosen from styrenes, substituted styrenes, butadiene with 1,4-addition, butadiene with 1,2-addition, compounds of formula (C.sub.1) ##STR00013## wherein Q.sup.1 and Q.sup.2 independently represent a hydrogen atom or a C.sub.1-C.sub.18-alkyl group.

Description

EXAMPLE 1: LUBRICATING COMPOSITIONS

[0100] The following lubricating compositions were prepared according to Table 2 below.

TABLE-US-00002 TABLE 2 Composition 1 Composition 2 (according to (according to Composition 3 Composition 4 the invention) the invention) (comparative) (comparative) (in % with (in % with (in % with (% with respect to respect to respect to respect to the total the total the total the total weight of the weight of the weight of the weight of composition) composition) composition) composition) Additives package 15.6 15.6 15.6 15.6 Base oil 84.2 81.4 83.6 83.7 Star-shaped 0 0 0.8 0.7 hydrogenated styrene/isoprene copolymer Alkyl methacrylate 0.2 3.0 0 0 polymer

[0101] The characteristics of the lubricating compositions are collated in Table 3 below:

TABLE-US-00003 TABLE 3 Composition 1 Composition 2 (according to (according to Composition 3 Composition 4 the invention) the invention) (comparative) (comparative) KV 40° C. 31.79 24.89 28.55 29.1 ASTM D445-97 (mm.sup.2/s) KV 100° C. 6.254 5.837 5.894 6.038 ASTM D445-97 (mm.sup.2/s) HTHS 150° C. 2.13 2.07 2.06 2.12 CEC L-036-90 or ASTM D4683 CCS −35° C. 5531 1804 4177 3941 ASTM D 5293 Noack 12.7% 11.7% 15.0% 12.0% ASTM D5800 or CEC L-040-93

EXAMPLE 2: MEASUREMENT OF THE NUMBER OF EMITTED PARTICLES

[0102] The compositions of example 1 were subject to the WLTC test and the quantity of particles per kilometer traveled with a size less than or equal to 23 nm emitted at the end of each cycle, was measured.

[0103] The engine tests were carried out on turbocharged straight-four engines. The tests were carried out at the same starting temperature of the engine. All other test bench conditions were kept constant as well. Sampling for the exhaust gas measurements was carried out from raw exhaust gases ahead from the exhaust system but after the treatment systems. Thus, the effects observed are indeed due solely to the use of the lubricating composition and thus to the use of the hydrogenated styrene-diene polymer and not to any other criterion such as the presence of a driver, the weight of the vehicle, the temperature, the relative humidity, etc.

[0104] The particle size distribution was measured in parallel by a Cambustion differential mobility spectrometer (DMS500). Same uses a high voltage discharge for charging every particle proportionally to the surface area thereof. The charged particles are introduced into a classification section with a strong radial electric field. Such field causes particles to drift through a flow inside a column, toward the electrometer detectors. The particles are detected at different distances in the column, depending on the aerodynamic resistance/charge ratio thereof. The outputs of the 22 electrometers are processed in real-time at 10 Hz, so as to provide spectral data and other measurements.

TABLE-US-00004 TABLE 4 Composition 1 Composition 2 (according to (according to Composition 3 Composition 4 the invention) the invention) (comparative) (comparative) (number of (number of (number of (number of particles with particles with particles with particles with size less than size less than size less than size less than or equal to or equal to or equal to or equal to 23 nm) 23 nm) 23 nm) 23 nm) Urban cycle 3.37E+10 3.93E+10 5.17E+10 5.15E+10 Peri-urban 2.88E+10 3.87E+10 4.43E+10 5.36E+10 cycle Road cycle 1.15E+10 1.74E+10 1.93E+10 2.08E+10 Freeway cycle 1.64E+10 1.42E+10 1.40E+10 1.16E+10 WLTC whole 1.970E+10  2.3562E+10  2.6904E+10  2.8380E+10  cycle (average weighted by the distance of every phase)

[0105] The results showed that the addition of an alkyl methacrylate polymer in a lubricating composition reduces the quantity—released from the exhaust—of particles with a size less than or equal to 23 nm.