阅读说明：本技术 作为润滑剂组合物的基料或润滑剂添加剂的氢化线性聚二烯共聚物 (Hydrogenated linear polydiene copolymers as base stocks or lubricant additives for lubricant compositions ) 是由 E·C·施魏辛格 Y·格罗-昂内布林克 H·普莱奇 于 2021-04-30 设计创作，主要内容包括：本发明涉及包含丁二烯和异戊二烯单体单元的氢化线性共聚物,以及制备这些共聚物的方法。本发明还涉及包含一种或多种根据本发明的氢化线性共聚物的润滑油组合物,以及涉及上述共聚物用作润滑剂组合物的润滑剂添加剂或合成基础流体的用途,尤其是在齿轮油、传动油、液压油、发动机油、润滑脂、船用油或者工业润滑油中的用途。(The present invention relates to hydrogenated linear copolymers comprising butadiene and isoprene monomer units, and to a process for preparing these copolymers. The invention also relates to a lubricating oil composition comprising one or more hydrogenated linear copolymers according to the invention, and to the use of the above-mentioned copolymers as lubricant additives or synthetic base fluids for lubricant compositions, especially in gear oils, transmission oils, hydraulic oils, engine oils, greases, marine oils or industrial lubricating oils.)

1. A hydrogenated linear copolymer obtainable by polymerizing a monomer composition consisting of:

a)10 to 60 mol% of a1, 3-butadiene monomer,

b) from 40 to 90 mole% of isoprene,

c)0 to 40 mol% of one or more (meth) acrylic acids C_1-C₆Alkyl esters, and

d)0 to 30 mol% of one or more (meth) acrylic acids C₇-C₂₄An alkyl ester, a carboxylic acid,

wherein the total amount of monomers a) and b) add up to at least 60 mole% of the total amount of the monomer composition, based on the total amount of monomers in the monomer composition, and

wherein the hydrogenated copolymer has a weight average molecular weight in the range of 2,000 to 30,000g/mol, and has a degree of hydrogenation of greater than 95%.

2. The hydrogenated linear copolymer according to claim 1, wherein the hydrogenated copolymer has a weight average molecular weight in the range of from 3,000g/mol to 20,000g/mol, preferably from 4,000g/mol to 18,000 g/mol.

3. The hydrogenated linear copolymer according to claim 1 or 2, wherein the hydrogenated copolymer has a PDI of 1.0 to 4.0, preferably 1.0 to 3.3.

4. The hydrogenated linear copolymer according to any one of the preceding claims, wherein the hydrogenated copolymer is a statistical copolymer or a block copolymer, preferably a statistical copolymer.

5. The hydrogenated linear copolymer according to any one of the preceding claims, wherein the monomer composition consists of:

a)10 to 60 mol% of a1, 3-butadiene monomer,

b) from 40 to 90 mole% of isoprene,

c)1 to 30 mol% of one or more (meth) acrylic acids C₁-C₆Alkyl esters, and

d)0 to 30 mol% of one or more (meth) acrylic acids C₇-C₂₄An alkyl ester;

based on the total amount of monomers in the monomer composition.

6. The hydrogenated linear copolymer according to any one of the preceding claims, wherein the monomer composition consists of:

a)10 to 60 mol% of a1, 3-butadiene monomer,

b) from 40 to 90 mole% of isoprene,

c)1 to 20 mol% of one or more (meth) acrylic acids C₁-C₆Alkyl esters, and

d)5 to 20 mol% of one or more (meth) acrylic acids C₇-C₂₄An alkyl ester;

based on the total amount of monomers in the monomer composition.

7. The hydrogenated linear copolymer according to any one of the preceding claims, wherein the one or more (meth) acrylic acids C₁To C₆The alkyl ester monomer c) is selected from methyl (meth) acrylate, butyl (meth) acrylate or mixtures thereof.

8. The hydrogenated linear copolymer according to any one of the preceding claims, wherein the one or more (meth) acrylic acids C₇To C₂₄The alkyl ester monomer d) is lauryl (meth) acrylate.

9. A process for preparing a hydrogenated copolymer as defined in any one of claims 1 to 8, wherein the process comprises the steps of:

(i) providing a monomer composition according to any one of claims 1 to 8,

(ii) initiating solution polymerization in said monomer composition to obtain a copolymer, and

(iii) (iii) hydrogenating the copolymer of step (ii).

10. The process according to claim 9, wherein the polymerization of step (ii) is a free radical or anionic solution polymerization, more preferably a free radical solution polymerization.

11. A lubricating oil composition comprising:

(x) One or more base oils, and

(y) one or more hydrogenated linear copolymers as defined in any one of claims 1 to 8.

12. The lubricating oil composition according to claim 11, wherein the one or more base oils are selected from the group consisting of polyalphaolefin base oils, API group III base oils, or mixtures thereof.

13. Lubricating oil composition according to claim 11 or 12, wherein the lubricating oil composition comprises from 0.5 to 80 wt.% of the one or more hydrogenated linear copolymers (y) and from 20 to 99.5 wt.% of the one or more base oils (x), based on the total amount of the lubricating oil composition.

14. Use of a hydrogenated linear copolymer as defined in any one of the preceding claims 1 to 8 as a lubricant additive or synthetic base fluid in a lubricating oil composition, preferably in a gear oil composition, a transmission oil composition, a hydraulic oil composition, an engine oil composition, a marine oil composition, an industrial lubricating oil composition or in a grease.

15. A method of improving the traction coefficient of a lubricating oil composition as defined in any one of claims 11 to 13, wherein the method comprises the step of adding one or more hydrogenated linear copolymers (y) to the one or more base oils (x).

Technical Field

The present invention relates to hydrogenated linear copolymers comprising butadiene and isoprene monomer units, and to a process for preparing these copolymers. The invention also relates to a lubricating oil composition comprising one or more hydrogenated linear copolymers according to the invention, and to the use of the above-mentioned copolymers as lubricant additives or synthetic base fluids for lubricant compositions, especially in gear oils, transmission oils, hydraulic oils, engine oils, greases (grease), marine oils or industrial lubricating oils.

Background

The present invention relates to the field of lubrication. Lubricants are compositions that reduce friction between surfaces. In addition to allowing freedom of movement between two surfaces and reducing mechanical wear of the surfaces, the lubricant may inhibit corrosion of the surfaces and/or may inhibit damage to the surfaces due to heat or oxidation. Examples of lubricant compositions include, but are not limited to, gear oils, transmission oils, hydraulic oils, engine oils, greases, marine oils, and industrial lubricating oils.

A typical lubricant composition includes a base fluid and optionally one or more additives. Conventional base fluids are naturally occurring hydrocarbons such as mineral oils or synthetic compositions such as poly-alpha-olefins, polyalkyl (meth) acrylates and ethylene-propylene copolymers. The terms "base oil" or "base fluid" are generally used interchangeably. Herein, "base fluid" is used as a generic term.

Various additives may be combined with the base fluid depending on the intended use of the lubricant. Examples of lubricant additives include, but are not limited to, oxidation inhibitors, corrosion inhibitors, dispersants, high pressure additives, anti-foaming agents, and metal deactivators. In order to improve the viscosity measurement performance, a Viscosity Index Improver (VII) and a thickener may be used. These viscosity modifiers are generally of the polymeric type.

However, one disadvantage of adding polymeric additives to lubricant formulations is that they experience shear stress and mechanical degradation over time. Polymers with higher molecular weights are better thickeners, but they are more susceptible to shear stress, leading to polymer degradation. By reducing the molecular weight of the polymer, a more shear stable polymer is obtained. However, these shear stable low molecular weight polymers are no longer very effective thickeners and must be used in greater concentrations in the lubricant in order to achieve the desired viscosity. These low molecular weight polymers typically have a molecular weight below 20,000g/mol and are also referred to as synthetic high viscosity base fluids.

Typical polymeric additives on the market, such as polyalkyl (meth) acrylates (PAMAs), have various disadvantages in different lubricating oil compositions. One example is that large amounts of PAMA product are required in these compositions to achieve the desired viscosity measurement properties. Another example is the solubility problem of PAMA products with different types of base oils. Another disadvantage of conventional PAMA-based lubricant additives is poor traction performance.

Alternatively, some lubricant additives are based on isoprene and butadiene, for example in US 7,163,913B2, which discloses linear, radial and star statistical copolymers of isoprene and butadiene wherein at least 70 wt% of butadiene is incorporated into the polymer and the weight ratio of isoprene to butadiene is in the range of 90:10 to 70:30, which are suitable for use as viscosity index improvers for lubricating oil compositions.

There remains a need to find new lubricant additives that not only combine high thickening efficiency, good oil solubility, good shear stability, high viscosity index in lubricating oil compositions, but also improve the traction properties of the lubricating oil compositions.

Disclosure of Invention

It is therefore an object of the present invention to provide a synthetic base fluid or lubricating oil additive for lubricating oil compositions which is highly efficient compared to the prior art. The purpose of these novel polymers is to provide excellent properties in lubricating oil compositions, in particular in terms of thickening efficiency, shear stability and traction. These shear stable polymers described should be able to thicken the oil to the desired viscosity using lower amounts of polymer than the typically used polyalkyl (meth) acrylates. In addition, the polymers should exhibit high viscosity index in lubricating oil compositions, as well as excellent solubility in typical base fluids.

Summary of The Invention

After intensive investigations, the inventors of the present invention have surprisingly found that hydrogenated linear copolymers consisting of butadiene, isoprene and optionally alkyl (meth) acrylate monomer units as defined in claim 1 provide excellent properties in lubricating oil compositions, in particular in terms of thickening efficiency and traction properties, when added to lubricating oil compositions.

A first object of the present invention is therefore a hydrogenated linear copolymer as defined in claim 1 and the claims dependent thereon.

A second object of the present invention relates to a process for the preparation of the hydrogenated linear copolymers according to the invention.

A third object of the present invention is a lubricating oil composition comprising a hydrogenated linear copolymer according to the present invention.

A fourth object of the present invention is the use of the hydrogenated linear copolymers according to the invention in lubricating oil compositions as synthetic base fluids or as lubricating additives in synthetic base fluids, in particular in gear oil compositions, transmission oil compositions, hydraulic oil compositions, engine oil compositions, marine oil compositions, industrial lubricating oil compositions, or in greases.

Another object of the present invention is a method for improving the traction coefficient of a lubricating oil composition, wherein said method comprises the step of adding a hydrogenated linear copolymer as defined in the present invention to the base oil of a lubricating oil composition.

Detailed Description

Hydrogenated polybutadiene-isoprene copolymer according to the present invention

According to a first aspect, the present invention relates to a hydrogenated linear copolymer obtainable by polymerizing a monomer composition consisting of:

a)10 to 60 mol% of a1, 3-butadiene monomer,

b) from 40 to 90 mole% of isoprene,

c)0 to 40 mol% of oneOr a plurality of (meth) acrylic acids C₁-C₆Alkyl esters, and

d)0 to 30 mol% of one or more (meth) acrylic acids C₇-C₂₄An alkyl ester, a carboxylic acid,

based on the total amount of monomers in the monomer composition,

wherein the total amount of monomers a) and b) add up to at least 60 mole% of the total amount of the monomer composition, and

wherein the hydrogenated linear copolymer has a weight average molecular weight in the range of 2,000 to 30,000g/mol and has a degree of hydrogenation of greater than 95%.

In fact, the inventors of the present invention have surprisingly found that the combination of butadiene and isoprene in the specific amounts defined above results in the formation of hydrogenated linear copolymers having good solubility in oil. According to the invention, the total amount of butadiene (monomer a) and isoprene (monomer b) in the hydrogenated polybutadiene isoprene copolymer must add up to at least 60 mol% of the total amount of the monomer composition, and the amount of butadiene should not exceed 60 mol% based on the total amount of the monomer composition. In contrast, as indicated in the experimental part of the present invention, the pure hydrogenated polyisoprene or the copolymer comprising isoprene and butadiene which do not satisfy the monomer unit proportions as defined in claim 1 do not have a good overall performance, in particular with respect to having a high thickening efficiency while maintaining good traction properties. Thus, when combining the two dienes together according to the proportions as defined in claim 1, it is unexpected to achieve excellent properties in oils.

According to a preferred embodiment of the present invention, the hydrogenated copolymer has a weight average molecular weight in the range between 3,000g/mol and 20,000g/mol, more preferably 4,000g/mol and 18,000g/mol, most preferably 5,000g/mol and 15,000 g/mol. The polymer having this weight average molecular weight has particularly good shear resistance and provides excellent improvement in viscosity measurement performance of the lubricant composition even in the case where the amount of the copolymer is low.

Preferably, the copolymers of the present invention have a very low degree of crosslinking and a narrow molecular weight distribution, which further contributes to their shear resistance. The low degree of crosslinking and narrow molecular weight are reflected in the polydispersity index of the copolymer. Preferably, the polydispersity index (PDI) of the copolymer according to the invention is in the range of 1.0 to 4.0, more preferably 1.0 to 3.3. For most industrial applications, a polydispersity index in the range of 1.0 to 3.3 is considered to be optimal with respect to the shear resistance of the copolymer. The polydispersity index is defined as the ratio of weight average molecular weight to number average molecular weight (Mw/Mn).

The weight and number average molecular weights were determined by gel permeation chromatography using commercially available polybutadiene calibration standards. The determination is preferably carried out by gel permeation chromatography according to DIN 55672-1, using THF as eluent.

According to a preferred embodiment of the invention, the hydrogenated linear copolymer is a statistical (static) copolymer or a block copolymer, preferably a statistical copolymer.

Monomer

In the present invention, isoprene may also be referred to as 2-methyl-1, 3-butadiene.

In the present invention, butadiene may also be referred to as 1, 3-butadiene.

According to a preferred embodiment, the hydrogenated linear copolymers according to the invention may optionally comprise, in addition to the monomers a) and b), a monomer derived from (meth) acrylic acid C₁-C₆Monomers of alkyl esters as monomers C), derived from (meth) acrylic acid C₇-C₂₄Monomers of alkyl esters as monomers d) or mixtures thereof.

The term "(meth) acrylic" refers to acrylic acid, methacrylic acid, and mixtures of acrylic acid and methacrylic acid; methacrylic acid is preferred. The term "(meth) acrylate" refers to an ester of acrylic acid, an ester of methacrylic acid, or a mixture of an ester of acrylic acid and an ester of methacrylic acid; esters of methacrylic acid are preferred.

The term "(meth) acrylic acid C_1-6By alkyl ester is meant a mixture of (meth) acrylic acid and having 1 to 6 carbon atomsEsters of straight or branched alcohols. The term includes (meth) acrylates formed with alcohols of a particular length alone, and also mixtures of (meth) acrylates formed with alcohols of different lengths. Similarly, the term "(meth) acrylic acid C_7-24Alkyl ester "means an ester formed from (meth) acrylic acid and a straight or branched alcohol having 7 to 24 carbon atoms.

Suitable (meth) acrylic acids C for the monomers C)_1-6The alkyl ester includes, for example, methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, isopropyl (meth) acrylate, n-butyl (meth) acrylate, isobutyl (meth) acrylate, and t-butyl (meth) acrylate. In a preferred embodiment, the preferred (meth) acrylic acid C_1-6The alkyl ester is methyl (meth) acrylate, butyl (meth) acrylate or a mixture of methyl (meth) acrylate and butyl (meth) acrylate. More preferably, the butyl (meth) acrylate is n-butyl (meth) acrylate.

Suitable (meth) acrylic acids C for the monomers d)_7-24Alkyl esters include, for example, 2-butyloctyl (meth) acrylate, 2-hexyloctyl (meth) acrylate, decyl (meth) acrylate, 2-butyldecyl (meth) acrylate, 2-hexyldecyl (meth) acrylate, 2-octyldecyl (meth) acrylate, undecyl (meth) acrylate, 5-methylundecyl (meth) acrylate, dodecyl (meth) acrylate, 2-methyldodecyl (meth) acrylate, 2-hexyldodecyl (meth) acrylate, 2-octyldodecyl (meth) acrylate, tridecyl (meth) acrylate, 5-methyltrodecyl (meth) acrylate, tetradecyl (meth) acrylate, 2-decyltetradecyl (meth) acrylate, dodecyl (meth) acrylate, decyl (meth) acrylate, dodecyl (meth) acrylate, dodecyl, Pentadecyl (meth) acrylate, hexadecyl (meth) acrylate, 2-methylhexadecyl (meth) acrylate, heptadecyl (meth) acrylate, 5-isopropylheptadecyl (meth) acrylate, 4-tert-butyloctadecyl (meth) acrylate, 5-ethyloctadecyl (meth) acrylate, 3-isopropyloctadecyl (meth) acrylate, octadecyl (meth) acrylate, nonadecyl (meth) acrylateEicosyl (meth) acrylate, cetyl eicosyl (meth) acrylate, stearyl eicosyl (meth) acrylate, behenyl (meth) acrylate or 2-decyltetradecyl (meth) acrylate. In a particularly preferred embodiment, the monomers d) comprise one or more (meth) acrylic acids C₁₀-C₁₆Alkyl ester, which refers to an ester formed from (meth) acrylic acid and a straight or branched alcohol having 10 to 16 carbon atoms. Preferably, monomer d) comprises lauryl (meth) acrylate ((meth) acrylic acid straight chain C)₁₂-C₁₅Alkyl esters).

Monomer composition

As indicated above, the present invention relates to a hydrogenated linear copolymer obtainable by polymerizing a monomer composition consisting of:

a)10 to 60 mol% of a1, 3-butadiene monomer,

b) from 40 to 90 mole% of isoprene,

c)0 to 40 mol% of one or more (meth) acrylic acids C₁-C₆Alkyl esters, and

d)0 to 30 mol% of one or more (meth) acrylic acids C₇-C₂₄An alkyl ester, a carboxylic acid,

based on the total amount of monomers in the monomer composition,

wherein the total amount of monomers a) and b) add up to at least 60 mole% of the total amount of the monomer composition, and

wherein the hydrogenated copolymer has a weight average molecular weight in the range of 2,000 to 30,000g/mol, and has a degree of hydrogenation of greater than 95%.

In a preferred embodiment, the monomer composition indicated above consists of the following monomers:

a)10 to 60 mol% of a1, 3-butadiene monomer,

b) from 40 to 90 mole% of isoprene,

c)0 to 20 mol% of one or more (meth) acrylic acids C₁-C₆Alkyl esters, and

d)0 to 20 mol% of one or more (meth) acrylic acids C₇-C₂₄An alkyl ester, a carboxylic acid,

based on the total amount of monomers in the monomer composition.

According to a preferred embodiment, the monomer composition as defined above may further comprise alkyl (meth) acrylate monomers c) or d) or mixtures thereof.

In a preferred embodiment, the monomer composition consists of the following monomers:

a)10 to 60 mol% of a1, 3-butadiene monomer,

b) from 40 to 90 mole% of isoprene,

c)1 to 30 mol% of one or more (meth) acrylic acids C₁-C₆Alkyl esters, and

d)0 to 30 mol% of one or more (meth) acrylic acids C₇-C₂₄An alkyl ester, a carboxylic acid,

based on the total amount of monomers in the monomer composition.

In a preferred embodiment, the monomer composition consists of the following monomers:

a)10 to 60 mol% of a1, 3-butadiene monomer,

b) from 40 to 90 mole% of isoprene,

c)1 to 20 mol% of one or more (meth) acrylic acids C₁-C₆Alkyl esters, and

d)0 to 30 mol% of one or more (meth) acrylic acids C₇-C₂₄An alkyl ester, a carboxylic acid,

based on the total amount of monomers in the monomer composition.

In another preferred embodiment, the monomer composition consists of the following monomers:

a)10 to 60 mol% of a1, 3-butadiene monomer,

b) from 40 to 90 mole% of isoprene,

c)1 to 20 mol% of one or more (meth) acrylic acids C₁-C₆Alkyl esters, and

d)5 to 20 mol% of one or moreMultiple (meth) acrylic acids C₇-C₂₄An alkyl ester, a carboxylic acid,

based on the total amount of monomers in the monomer composition.

According to a preferred embodiment, in the preferred monomer compositions defined above, the one or more (meth) acrylic acids C₁To C₆The alkyl ester monomer C) is selected from methyl (meth) acrylate, butyl (meth) acrylate or mixtures thereof, and the one or more (meth) acrylic acid C₇To C₂₄The alkyl ester monomer d) is lauryl (meth) acrylate.

Process for preparing the copolymers of the invention

As explained above, the hydrogenated polybutadiene-isoprene copolymer of the present invention is prepared according to a method comprising the steps of:

(i) providing a monomer composition as defined above,

(ii) initiating solution polymerization in said monomer composition to obtain a copolymer, and

(iii) (iii) hydrogenating the copolymer of step (ii).

Polymerization step (ii)

According to a preferred embodiment, the polymerization of step (ii) is a radical polymerization or an anionic polymerization in solution, more preferably a radical polymerization in solution.

Free radical polymerization

Standard free-radical polymerization is described in detail in particular in Ullmann's Encyclopedia of Industrial Chemistry, sixth edition. Generally, a polymerization initiator and optionally a chain transfer agent are used for this purpose.

The copolymers of the invention are obtainable via the ATRP process. Such a reaction scheme is described, for example, by J.Am.Cheng et al in J.Am.chem.Soc, Vol.117, p.5614-5615 (1995), by Matyjaszewski in Macromolecules, Vol.28, p.7901-7910 (1995). In addition, patent applications WO 96/30421, WO 97/47661, WO 97/18247, WO 98/40415 and WO 99/10387 disclose variants of the ATRP set forth above.

In addition, the copolymers of the invention can also be obtained via the RAFT process. For example, the RAFT method is described in detail in WO 98/01478 and WO 2004/083169.

According to a preferred embodiment, the statistical copolymer of the invention is prepared by free radical solution polymerization, in which case the reaction mixture during step (ii) preferably comprises the monomer composition (step (i)), one or more free radical initiators, a solubilizing carrier medium as described hereinafter and optionally one or more chain transfer agents.

Solution polymerization is the preferred method for carrying out the process of the invention, since it allows the concentration of the monomer composition in the reaction mixture to be adjusted by adding more or less solubilizing carrier medium. By selecting the correct concentration of the monomer composition in the reaction mixture, the molecular weight and polydispersity index of the resulting copolymer can be controlled.

Preferably, the total amount of monomer composition in the reaction mixture is from 5 to 95 weight percent, more preferably from 10 to 70 weight percent, even more preferably from 20 to 55 weight percent, most preferably from 35 to 50 weight percent, based on the total weight of the reaction mixture. On an industrial scale, monomer concentrations of more than 20% are generally preferred. Monomer composition concentrations in the range of 20 to 55 wt.%, preferably 35 to 50 wt.%, based on the total weight of the reaction mixture, are considered optimal because they produce statistical copolymers having low weight average molecular weights in the range of 2,000 to 30,000g/mol and low polydispersity indices in the range of 1.0 to 3.3.

The polymerization is preferably carried out at a temperature of from 20 ℃ to 200 ℃, more preferably from 50 ℃ to 150 ℃, the reaction pressure is preferably from 1 bar to 30 bar, more preferably from 10 bar to 28 bar, and the total reaction time of the free-radical polymerization is from 1 to 10 hours.

Preferably, the solubilizing carrier medium used is selected from the group consisting of mineral oils, synthetic oils, ketones, ester solvents, aromatic hydrocarbons, cycloaliphatic hydrocarbons and aliphatic hydrocarbons or mixtures thereof.

Examples of mineral oils are paraffinic, naphthenic, solvent refined, high VI oils containing isoparaffins, and hydrocracked high VI oils. Examples of synthetic oils are organic esters, e.g., diesters and polyesters, such as carboxylic acid esters and phosphoric acid esters; organic ethers such as silicone oils, perfluoroalkyl ethers, and polyalkylene glycols; and synthetic hydrocarbons, especially polyolefins and gas to oil (GTL). Examples of ketones are butanone and methyl ethyl ketone. Examples of ester solvents are fatty oils, and synthetic ester lubricants (e.g., C4-12 dicarboxylic acid di-C4-12 alkyl esters, such as dioctyl sebacate and dioctyl adipate, polyol poly-C4-12 alkanoates, such as pentaerythritol tetrahexanoate, and tri-C4-12 alkyl phosphates, such as tri-2-ethylhexyl phosphate, (dibutyl) (phenyl) phosphate, (di-2-ethylhexyl) (phenyl) phosphate, (2-ethylhexyl) (diphenyl) phosphate, and tricresyl phosphate). Examples of aromatic hydrocarbons are benzene, toluene, xylene, ethylbenzene, trimethylbenzene, ethyltoluene and mixtures thereof. Examples of alicyclic hydrocarbons are cyclohexane, methylcyclohexane and alicyclic terpenes. Examples of aliphatic hydrocarbons are n-pentane, n-hexane, n-heptane, 1-decene and aliphatic terpenes.

In a preferred embodiment, the solubilizing carrier medium is a cycloaliphatic or aliphatic or aromatic hydrocarbon, preferably cyclohexane or toluene.

Step (ii) comprises adding a free radical initiator.

Suitable free-radical initiators are, for example, azo initiators, such as Azobisisobutyronitrile (AIBN), 2' -azobis (2-methylbutyronitrile) (AMBN) and 1, 1-azobiscyclohexanecarbonitrile, and peroxy compounds, such as methyl ethyl ketone peroxide, acetylacetone peroxide, dilauryl peroxide, ketone peroxide, tert-butyl peroctoate, methyl isobutyl ketone peroxide, cyclohexanone peroxide, dibenzoyl peroxide, tert-butyl peroxybenzoate, tert-butyl peroxyisopropylcarbonate, 2, 5-bis (2-ethylhexanoylperoxy) -2, 5-dimethylhexane, tert-butyl peroxy-3, 5, 5-trimethylhexanoate, dicumyl peroxide, 1-bis (tert-butylperoxy) cyclohexane, 1-bis (tert-butylperoxy) -3,3, 5-trimethylcyclohexane, cumyl hydroperoxide, tert-butyl hydroperoxide and bis (4-tert-butylcyclohexyl) peroxydicarbonate.

Preferably, the free radical initiator is selected from the group consisting of 2,2' -azobis (2-methylbutyronitrile), 2-bis (t-butylperoxy) butane, 1-di-t-butylperoxy-3, 3, 5-trimethylcyclohexane, t-butyl peroxybenzoate and t-butyl peroxy-3, 5, 5-trimethylhexanoate. In a particularly preferred embodiment, the free radical initiator is 2, 2-bis (t-butylperoxy) butane.

Preferably, the total amount of free radical initiator is from 0.01 to 5 wt. -%, more preferably from 0.02 to 1 wt. -%, most preferably from 0.05 to 0.5 wt. -%, relative to the total weight of the monomer mixture.

The total amount of free radical initiator may be added in a single step, or the free radical initiator may be added in multiple steps during the polymerization reaction. For example, a portion of the free radical initiator may be added to initiate free radical polymerization, and a second portion of the free radical initiator may be added 0.5 to 3.5 hours after the initial dose. Preferably, the free radical initiator is added in one single step.

Step (ii) optionally comprises adding a chain transfer agent. Examples of chain transfer agents are sulfur-containing compounds, such as mercaptans, e.g., n-dodecyl mercaptan, t-dodecyl mercaptan, 2-mercaptoethanol and mercaptocarboxylic esters, e.g., methyl 3-mercaptopropionate, or longer alkenes. Preferred chain transfer agents are olefins having up to 20 carbon atoms, especially up to 15 carbon atoms and more preferably up to 12 carbon atoms.

After the free radical polymerization is complete, the product is preferably filtered to remove any impurities present in the reaction mixture, followed by evaporation of any volatile solvent.

Anionic polymerization

An alternative way of carrying out step (ii) of the process is to prepare the polybutadiene-isoprene polymer of the present invention by living anionic polymerization via butadiene and isoprene monomers.

This type of reaction is well established and is described in detail in h.l. hsieh, r.p. quick, ionic Polymerization, Principles and Practical Applications, 1996, Marcel Dekker, inc.

For the living anionic polymerization of 1, 3-butadiene and isoprene, a batch or semi-batch type process is preferred according to the present invention. Living polymerization in a continuous process is also contemplated.

The polymerization is generally carried out in an aliphatic, alicyclic or aromatic hydrocarbon solvent. Examples of aliphatic hydrocarbon solvents are hexane or heptane. Examples of alicyclic hydrocarbon solvents are cyclohexane or methylcyclohexane. Examples of aromatic hydrocarbon solvents are benzene or toluene. Polar heteroaliphatic solvents such as tertiary amines and/or ethers and/or cyclic ethers may also be used as solvents or co-solvents. Examples of tertiary amines are tetramethylenediamine or N, N, N' -pentamethyldiethylenediamine. Examples of ethers or cyclic ethers are diethyl ether and tetrahydrofuran. Usually a solvent mixture of an aliphatic, alicyclic or aromatic hydrocarbon solvent and a polar heteroaliphatic solvent is used.

Typical initiators are organometallic agents in which the metal is from the alkali metal class or from the alkaline earth metal class. Typical examples are mono-or difunctional organic sodium, lithium or potassium salts as initiators, for example n-butyllithium, sec-butyllithium, tert-butyllithium, 1-diphenylhexyllithium, diphenylmethyllithium, 1,4,4, -tetraphenyl-1, 4-dilithiobutane, lithium naphthalene and their sodium and potassium homologues. Preferably, organolithium initiators are used, more preferably n-butyllithium initiators.

The living nature of anionic polymerization provides excellent control of the resulting molecular weight and polydispersity index (PDI) with the exclusion of oxygen and protic reagents.

Typically, the polymerization reaction is terminated using a protic reagent, such as methanol, ethanol, 2-propanol or water, for neutralizing the macromolecular anions.

Typical reaction temperatures range between 10 ℃ and 120 ℃ and typical reaction pressures range between 1 and 100 bar.

Hydrogenation step (iii)

On an industrial scale for use in the present invention, it is desirable to provide hydrogenated copolymers in which no double bonds are present, since the presence of double bonds reduces the reactivity of the copolymer against chemical oxidation, crosslinking or other undesirable side reactions. Thus, in step (iii), the inventors of the present invention carried out a selective hydrogenation of the diene units, as described below.

According to the invention, the monomer units derived from butadiene and isoprene are hydrogenated. To improve stability against oxidation, a high degree of hydrogenation of the polyisoprene-butadiene copolymer of greater than 95% relative to the polymerized units derived from butadiene and isoprene is desirable. The hydrogenation is selective and does not affect the monomer units c) and d) derived from the optional (meth) acrylate.

The selectivity of the hydrogenation can be determined, for example, by quantification¹H nuclear magnetic resonance (¹H NMR) spectroscopy or Infrared (IR) spectroscopy. The degree of hydrogenation is defined as the molar saturation, relative to the non-hydrogenated starting material, of the carbon-carbon bonds derived from the polymerized units of the conjugated diene achieved by hydrogenation. The degree of hydrogenation of the statistical copolymers according to the invention is determined by using dimethyl terephthalate as standard, in a deuterated chloroform solution¹H NMR spectroscopy was performed. Chemical shifts were calibrated using solvent signals. To determine the degree of hydrogenation, the corresponding signal integrals of the standards were correlated with the signal integrals of the olefinic protons. For each sample, the measurement and determination must be repeated using a non-hydrogenated reference sample in order to define a degree of hydrogenation of 0%.

The selective hydrogenation of the copolymers of the invention is generally carried out in the presence of at least one solubilizing carrier medium, using hydrogen or other hydrogen source as reducing agent, either in heterogeneous form using an insoluble supported metal or metal complex catalyst or in homogeneous form using a soluble organometallic catalyst. A detailed description of homogeneous catalytic hydrogenation can be found, for example, in US 3,541,064 and GB 1,030,306. Heterogeneous catalysis using insoluble supported metals as catalysts is widely used in industrial selective hydrogenation processes and is generally superior to other processes because of the economic advantages it offers. Preferably, the selective hydrogenation process is a heterogeneous catalytic process using an insoluble supported metal as catalyst.

Typical catalytically active metals for heterogeneously catalyzing the selective hydrogenation according to the invention include, but are not limited to, Ru, Rh, Pd, Ir, Pt, Mn, Cr, Fe, Co, Ni, U, Cu, Nd, In, Sn, Zn, Ag, Cr and alloys of one or more of these metals.

Typical catalyst supports include, but are not limited to, oxides (Al)₂O₃、TiO₂、SiO₂Or other oxide), carbon, diatomaceous earth, or other support.

In addition, the heterogeneous catalyst may be used, for example, in the form of pellets or powder.

In a preferred embodiment, the selective hydrogenation process is preferably carried out using a heterogeneous carbon supported Pd catalyst in powder form. The use of a carbon-supported Pd catalyst is preferred because it performs hydrogenation of double bonds derived from butadiene and isoprene with high selectivity and reactivity.

The amount of the catalytically active metal supported on the carrier is preferably from 0.1 to 10% by weight, more preferably from 1 to 10% by weight, based on the total weight of the supported catalyst.

In the case of hydrogen as reducing agent, the reaction pressure is preferably from 5 to 1500 bar, either as a constant pressure or as a gradient pressure. More preferably, the reaction pressure is from 5 to 500 bar, even more preferably from 5 to 250 bar, and most preferably from 10 to 90 bar.

In the hydrogenation step (iii), the concentration of statistical copolymer in the solubilizing carrier medium may typically be in the range of 5 to 95% by weight. Preferably, the concentration of the statistical copolymer in the solubilizing carrier medium is from 10 to 70 wt% of the statistical copolymer, based on the total weight of copolymer and carrier medium.

In a preferred embodiment, the hydrogenation is carried out in the presence of an alicyclic or aliphatic hydrocarbon, preferably cyclohexane.

The reaction temperature in the hydrogenation step (iii) is preferably from 0 to 200 ℃, more preferably from 20 to 150 ℃, even more preferably from 20 to 120 ℃.

In a particularly preferred embodiment, the hydrogenation is carried out at a temperature of from 20 to 120 ℃, at a pressure of from 10 to 90 bar, in the presence of a carbon-supported Pd catalyst, and in the presence of cyclohexane as the solubilizing support medium. These conditions have been found to be optimal for the preparation of the above copolymers, since they lead to high reactivity and selectivity in the selective hydrogenation of the double bonds derived from the conjugated diene.

Lubricating oil composition

The invention also relates to a composition comprising

(x) One or more base oils, and

(y) one or more of the above-mentioned hydrogenated linear copolymers of the present invention.

The lubricant compositions of the present invention preferably have a viscosity index greater than 140. The viscosity index may be measured according to ASTM D2270.

Preferably, the lubricating oil composition comprises from 0.5 to 80 wt.%, more preferably from 1 to 50 wt.%, even more preferably from 1 to 30 wt.%, most preferably from 1 to 15 wt.% of the one or more hydrogenated linear copolymers, and from 20 to 99.5 wt.%, more preferably from 50 to 99 wt.%, even more preferably from 70 to 99 wt.%, most preferably from 85 to 99 wt.%, based on the total amount of the lubricating oil composition, of the one or more base oils.

If the lubricant composition according to the invention is used as an engine oil, it preferably comprises from 0.5 to 20% by weight, based on the total weight of the lubricant composition, of a copolymer according to the invention, which results in a viscosity of 3mm according to ASTM D445²S to 10mm²Kinematic viscosity at 100 ℃ in the range/s.

If the lubricant composition of the invention is used as an automotive gear oil, it preferably comprises from 2 to 35% by weight, based on the total weight of the lubricant composition, of a copolymer according to the invention, which results in a viscosity of 2mm according to ASTM D445²S to 15mm²Kinematic viscosity at 100 ℃ in the range/s.

If the lubricant composition of the invention is used as an automatic transmission oil, it preferably comprises from 1 to 25% by weight, based on the total weight of the lubricant composition, of a copolymer according to the invention in the base oil, which results in a composition according to ASTM D445 at 2mm²S to 9mm²Kinematic viscosity at 100 ℃ in the range/s.

If the lubricant composition of the invention is used as an industrial gear oil, it preferably comprises from 15 to 80% by weight, based on the total weight of the lubricant composition, of a copolymer according to the invention, which results in 10mm according to ASTM D445²S to 130mm²Kinematic viscosity at 100 ℃ in the range/s.

If the lubricant composition of the invention is used as a hydraulic oil, it preferably comprises from 1 to 20% by weight, based on the total weight of the lubricant composition, of a copolymer according to the invention, which results in a viscosity of 3mm according to ASTM D445²S to 20mm²Kinematic viscosity at 100 ℃ in the range/s.

Preferably, the amounts of (x) and (y) add up to 100 wt.%, based on the total weight of the lubricant composition.

Base oil

The base oil that may be used in the composition preferably comprises one or more oils of lubricating viscosity. Such oils correspond to lubricant base fluids, mineral, synthetic or natural, animal or vegetable oils, suitable for their application/chosen according to the intended use.

The base fluid used to formulate the lubricating oil compositions according to the present invention includes, for example, conventional basestocks selected from the API (american petroleum institute) basestock class, which is referred to as group I, group II, group III, group IV and group V. The group I and II basestocks are mineral oil materials (e.g., paraffinic and naphthenic oils) having a viscosity index (or VI) of less than 120. Group I is further distinguished from group II in that the latter contains greater than 90% saturated material, while the former contains less than 90% saturated material (i.e., greater than 10% unsaturated material). Group III is considered the highest level mineral base fluid having a VI of greater than or equal to 120 and a saturates level of greater than or equal to 90%. Group IV base fluids are Polyalphaolefins (PAO). Group V base fluids are esters and any other base fluids not included in group I through IV base fluids. These base fluids may be used alone or as a mixture.

Preferably, the one or more base oils (x) are selected from polyalphaolefin base oils, API group III base oils or mixtures thereof.

Additional additives

The lubricating oil composition according to the present invention may further comprise any other additional additive (z) suitable for use in the formulation. These additives are selected from the group consisting of viscosity index improvers, pour point improvers, dispersants, demulsifiers, lubricity additives, detergents, antifoamants, corrosion inhibitors, friction modifiers, antioxidants, antiwear additives, extreme pressure additives, anti-fatigue additives, dyes, odorants, or mixtures thereof. Preferably, the lubricating oil composition according to the present invention comprises a Pour Point Depressant (PPD) to reduce the minimum temperature at which the fluid will flow or be able to be poured. Such additives are well known. Typical of those PPDs include ethylene-vinyl acetate copolymers, chlorinated paraffin-naphthalene condensates, chlorinated paraffin-phenol condensates, polymethacrylates, polyalkylstyrenes. Preference is given to polymethacrylates having a mass average molecular weight of from 5,000 to 200,000 g/mol.

Preferably, the amounts of components (x), (y) and (z) add up to 100 wt.%, based on the total weight of the lubricating oil composition.

Use of the hydrogenated Linear copolymers according to the invention

The present invention relates to the use of the hydrogenated linear copolymers according to the invention as lubricating oil additives or synthetic base fluids, depending on the treat-rate in the lubricating oil composition, preferably in gear oil compositions, transmission oil compositions, hydraulic oil compositions, engine oil compositions, marine oil compositions, industrial lubricating oil compositions, or in greases.

As demonstrated in the experimental section below, the use of the hydrogenated linear copolymers according to the invention in lubricating oil compositions allows to improve the traction coefficient of the lubricating oil compositions while maintaining excellent thickening efficiency and shear stability in the compositions.

The present invention also relates to a method of improving the traction coefficient of a lubricating oil composition, wherein the method comprises the steps of: the hydrogenated linear copolymer according to the invention and as described in detail above is added to the base oil.

As demonstrated in the experimental section below, there is an excellent improvement in traction coefficient and thickening efficiency in lubricating oil compositions due to the advantageous effect of the hydrogenated linear copolymer according to the present invention. In addition, the hydrogenated linear copolymers as defined in the present invention maintain high viscosity index, good shear stability, excellent low temperature properties and excellent solubility in typical base fluids.

Detailed Description

Experimental part

The present invention is further illustrated in detail below with reference to examples and comparative examples, without intending to limit the scope of the present invention.

Abbreviations

PMMA polyalkyl (meth) acrylate

MMA methacrylic acid C₁-alkyl ester ═ methyl methacrylate

BMA methacrylic acid C₄-alkyl ester ═ n-butyl methacrylate

LMA methacrylic acid C_12/14-alkyl ester ═ lauryl methacrylate

KRL Kegelrolellager (taper roller bearing)

KV₄₀Kinematic viscosity at 40 ℃ measured according to ASTM D445

KV₁₀₀Kinematic viscosity at 100 ℃ measured according to ASTM D445

M_nNumber average molecular weight

M_wWeight average molecular weight

NB3030 NexbaseGroup III base oils from Neste with KV of 3.0cSt₁₀₀

NB3043 NexbaseGroup III base oils from Neste with KV of 4.3cSt₁₀₀

PDI polydispersity index via M_w/M_nCalculated molecular weight distribution

PSSI100 permanent shear stability index (based on KV before and after shearing)₁₀₀Calculating)

VI viscosity index measured according to ASTM D2270

GPC gel permeation chromatography

MTM micro traction tester

The pour point of PP is measured according to ASTM D97.

T_gGlass transition temperature measured via differential scanning calorimetry

BF Brookfield viscosity measured at-40 ℃ according to ASTM D2983

Sample preparation

Synthesis of polymers

Copolymers 1 to 8 of the present invention and comparative examples 10 to 12 were prepared by radical solution polymerization using the monomer compositions shown in table 1 below. The monomer was mixed with toluene in a 5 liter autoclave at a temperature of 20 ℃ and a pressure of 10 bar, so that the concentration of the monomer relative to the total weight of the mixture was 40% by weight. The temperature was raised to 130 ℃ using a heating rate of 5.5 ℃/min, and then the initiator, 2, 2-bis (t-butylperoxy) butane (50% by weight in liquid paraffin), was added. The free-radical copolymerization is carried out at a reaction temperature of 130 ℃, a reaction pressure of about 20 bar and a reaction time of 3 hours. The effluent was filtered and the volatile solvent was evaporated. The copolymer obtained is then subjected to selective hydrogenation.

Hydrogenation of copolymers

For the selective hydrogenation, 1.5 liters of a 40 wt% solution of the unsaturated copolymer in cyclohexane were charged to a 2 liter autoclave and 0.15 wt% of Pd per polymer of 5% Pd/C catalyst powder was introduced. At 90 deg.CReaction temperature and 90 bar H₂The hydrogenation is carried out under stirring under reaction pressure until a degree of hydrogenation of 95% or more is achieved. The effluent was filtered and the volatile components evaporated. All polymerized units except those derived from conjugated dienes (butadiene and isoprene) are not converted during the selective hydrogenation. All of the copolymers 1 to 8 of the present invention and comparative examples 10 to 12 were hydrogenated in accordance with this procedure.

Examples (as also shown in Table 1 below)

Examples 1 to 4 of the present invention are based on monomer compositions of butadiene and isoprene.

Examples 5 and 6 according to the invention are monomer compositions based on butadiene, isoprene and methyl (meth) acrylate.

Examples 7 and 8 of the present invention are monomer compositions based on butadiene, isoprene, methyl (meth) acrylate, butyl (meth) acrylate and lauryl (meth) acrylate.

Comparative example 9, PAMA, is C synthesized according to example 1 in US2013/0229016A1_12-15Copolymers of methacrylic acid esters.

Comparative example 10 is a copolymer of 80 mol% (76 wt%) butadiene and 20 mol% (24 wt%) isoprene, as disclosed for example in US 7,163,913B 2.

Comparative example 11 monomer composition based on butadiene, methyl (meth) acrylate, butyl (meth) acrylate and lauryl (meth) acrylate. This product was synthesized using the same method as in the examples of the present invention.

Comparative example 12 is based on pure polyisoprene and was synthesized using the same method as the examples of the invention.

Bulk Polymer Properties

Test method

The hydrogenated Linear copolymer of the present invention has a weight average molecular weight M_wAnd polydispersity index PDI was determined using Tosoh EcoSEC GPC system "HLC-8320" at a flow rate of 0.3 mL/min at T ═ 40 ℃ using Tetrahydrofuran (THF) as the eluent against polybutadiene calibration standardsThe Tosoh EcoSeC GPC system "HLC-8320" was equipped with a PSS SDV 5 μm pre-column and a 30cm PSS SDV 5 μm linear S separation column, and an RI detector.

The weight average molecular weight of the polyalkyl (meth) acrylate of comparative example 9 was determined by Gel Permeation Chromatography (GPC) using polymethyl methacrylate calibration standards and THF as eluent.

The composition of the copolymer of the invention, the degree of hydrogenation and the selectivity of the hydrogenation process are aided by the use of a catalyst in deuterated chloroform¹H-NMR spectroscopy.

The glass transition temperature was measured via differential scanning calorimetry on a Mettler-Toledo DSC 1. The analysis was performed using Mettler Toledo STARe 10.00 software. Indium and cyclohexane were used as standards. In two heating/cooling cycles, 8 to 10mg of sample was cooled to-80 ℃ at a cooling rate of 20K/min. After 10 minutes, the sample was heated to 200 ℃ at a heating rate of 10K/min. The glass transition temperature is obtained from the second heating cycle.

As reflected in table 1 below, the bulk properties of the hydrogenated linear copolymers of the present invention are all very satisfactory, having low PDI values, Mw and glass transition temperature. In addition, a high level of control during the synthesis is observed, since the PDI values of the hydrogenated copolymers of the invention are all below 3.3.

In addition, the hydrogenated linear copolymers of the invention obtained all have a high hydrogenation level (more than 96% of the isoprene and butadiene are hydrogenated). The degree of hydrogenation was calculated as described above in the section on hydrogenation.

Evaluation of Lubricant compositions

The use of the inventive copolymer as a lubricant additive was demonstrated in two different lubricant formulations with different inventive hydrogenated linear copolymers.

Test method

The formulations in Table 3 have a KV100 target value of 7.0 cSt-in the tapered roller bearing test (KRL) according to CEC-L-45-A-99, the viscosity loss at 100 ℃ relative to the kinematic viscosity of fresh oil at 100 ℃ is measured after 40 hours at 80 ℃.

The formulations in table 4 have fixed VI-KV 40 with a target value of 26cSt and KV100 with a target value of 5.5 cSt. The traction coefficient was measured on a micro traction tester using an 3/4 inch ball loaded on a disk using the following conditions as shown in table 2 below:

table 2:

kinematic viscosity was measured according to ASTM D445.

Viscosity index was determined according to ASTM D2270.

The brookfield viscosities reported in the lubricant formulation examples in table 3 were measured at a temperature of-40 ℃ according to ASTM D2983.

The Pour Points (PP) of the examples shown in table 3 were measured according to ASTM D97.

Lubricating oil formulation 1(KV100 ═ 7.0cSt)

As shown in table 3 below, some lubricating oil compositions were prepared comprising an API group III base fluid (Nexbase 3030), a commercially available additive package, and either copolymers 1 through 8 of the present invention or comparative examples 9 and 10. For comparison of the lubricating oil compositions alone, the kinematic viscosity at 100 ℃ was adjusted to 7.0 cSt.

For each composition, the viscosity measuring properties were measured as well as the shear stability (KRL) and low temperature properties.

The advantage of the present invention is that low amounts (throughput) of the copolymers of the invention from 1 to 8 are sufficient to achieve good kinematic viscosities and good viscosity indices. In contrast, the formulation comprising comparative PAMA additive 9 achieved similar results to the inventive formulation, but where the treat rate was greater than 20 wt% (twice the amount of the inventive formulation).

Thus, unexpectedly, even though the additives of the present invention have low molecular weights, they are still very effective thickeners, even at low concentrations in the lubricant formulation.

Although in the case of comparative example 10, similar results in terms of treatment rate and VI to those of the inventive example were observed, the low temperature performance of comparative example 10 did not meet the requirements for industrial applications. Thus, copolymers with high butadiene to isoprene ratios are shown to be unsuitable for preparing good lubricant additives.

Lubricant formulation (fixed VI)

As shown in Table 4 above, a second type of lubricating oil formulation was prepared and the traction coefficient of each formulation comprising copolymers 1 to 8 according to the present invention and comparative polymers 9 to 12 was measured. The lubricating oil formulations of table 4 are all based on a mixture of any of group III base fluids (Nexbase 3030 and Nexbase 3043), commercially available additive packages, and the copolymer of the present invention or the comparative example.

For direct comparison of the individual lubricating oil compositions, the kinematic viscosity at 100 ℃ of each composition was adjusted to 5.5cSt, and the kinematic viscosity at 40 ℃ of each composition was adjusted to 26.0 cSt.

For each composition, the viscosity measuring properties and traction coefficient were determined (see table 4 above). Lubricant compositions containing PAMA additives exhibit poor traction performance and therefore serve as reference points for comparing different traction results of other lubricant compositions.

As shown in table 4 above, the traction coefficient is superior for the inventive examples compared to the comparative examples, which demonstrates the additional advantageous effect of using the lubricant additive according to the present invention.

In summary, it has been demonstrated that the hydrogenated copolymers according to the invention meet the requirements of the lubricant technology field by having a lower treat-rate, which is always sought after, in order to avoid thickening of the lubricant formulation and to reduce the risk of incompatibility with other components in the lubricant formulation. Furthermore, there is also a clear advantageous effect on the traction properties of lubricant formulations comprising the lubricant additives according to the invention.