Use of hydrogenated diene styrene polymer to reduce particulate emissions

Abstract

The present application relates to the use of a lubricant composition comprising a base oil and a hydrogenated diene styrene polymer to reduce engine particulate emissions.

Claims

1. A method of reducing particle emissions in a motor vehicle engine comprising at least one step of bringing into contact the engine with a lubricating composition, the lubricating composition comprising a base oil and a star-shaped hydrogenated styrene diene polymer, wherein the diene polymer is a hydrogenated isoprene unit.

2. The method according to claim 1, wherein the content of hydrogenated diene units is from 50 to 98%, with respect to the weight of the polymer.

3. The method according to claim 1, wherein the content of styrene units is from 2 to 50%, with respect to the weight of polymer.

4. The method according to claim 1, wherein the hydrogenated styrene diene polymer is used in an amount of 0.1 to 15% by weight with respect to the total weight of the lubricating composition.

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

6. The method according to claim 1 wherein the reduction of particulate emissions relates to the urban, peri-urban and road-type cycles, said cycles being defined by the Worldwide Harmonized Light vehicles Test Procedures and/or related to the whole Worldwide Harmonized Light vehicles Test Procedures.

7. A method for reducing particle emission in a motor vehicle engine lubricated with a lubricating composition comprising the addition of a star-shaped hydrogenated styrene diene polymer to said lubricating composition, wherein the diene polymer is a hydrogenated isoprene unit.

8. The method according to claim 7, wherein the particles have a size greater than or equal to 23 nm.

9. The method according to claim 7, wherein the reduction of particulate emissions relates to the urban, peri-urban and road-type cycles, said cycles being defined by the Worldwide Harmonized Light vehicles Test Procedures and/or related to the whole Worldwide Harmonized Light vehicles Test Procedures.

Description

EXAMPLE 1: LUBRICATING COMPOSITIONS

(1) The following lubricating compositions were prepared according to Table 2 below.

(2) TABLE-US-00002 TABLE 2 Composition 1 Composition 2 (according to the (according to the Composition 3 invention) (in % with invention) (in % with (comparative) (in % respect to the total respect to the total with respect to the weight of the weight of the total weight of the composition) composition) composition) Additives package 15.6 15.6 15.6 Base oil 83.6 83.7 84.4 Star-shaped 0.8 0.7 hydrogenated styrene/isoprene copolymer

(3) The characteristics of the lubricating compositions are collated in Table 3 below:

(4) TABLE-US-00003 TABLE 3 Composition 1 Composition 2 (according to (according to Composition 3 the invention) the invention) (comparative) KV 40 C. 28.55 29.1 32.58 ASTM D445-97 (mm.sup.2/s) KV 100 C. 5.894 6.038 6.407 ASTM D445-97 (mm.sup.2/s) HTHS 150 C. 2.1 2.1 2.2 CEC L-036-90 or ASTM D4683 CCS 35 C. 4177 3941 4176 ASTM D 5293 Noack 15% 12% 7.8% ASTM D5800 or CEC L-040-93

EXAMPLE 2: MEASUREMENT OF THE NUMBER OF EMITTED PARTICLES

(5) The compositions of example 1 were subjected to the WLTC test and the quantity of particles per kilometer traveled having a size greater than or equal to 23 nm emitted at the end of each cycle was measured.

(6) 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.

(7) 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.

(8) TABLE-US-00004 TABLE 4 Composition 1 Composition 2 (according to the (according to the Composition 3 invention) (number of invention) (number of (comparative) (number particles with size particles with size of particles with size greater than 23 nm) greater than 23 nm) greater than 23 nm) Urban cycle 7 10.sup.8 5.82 10.sup.8 1.34 10.sup.9 Peri-urban cycle 5.22 10.sup.8 4.88 10.sup.8 6.30 10.sup.8 Road cycle 3.52 10.sup.8 3.25.10.sup.8 5.90 10.sup.8 Freeway cycle 3.29 10.sup.8 2.30 10.sup.8 2.77 10.sup.8 WLTC whole cycle 4.2539 10.sup.8 3.5934 10.sup.8 5.8817 10.sup.8 (average weighted by the distance of every phase)

(9) The results show that the addition of a hydrogenated styrene isoprene polymer in a lubricating composition reduces the quantityreleased from the exhaustof particles with a size greater than or equal to 23 nm.