KR101856251B1 - A cold-proof grease composition for reducing noise - Google Patents

Abstract

More particularly, the present invention relates to a method for maintaining a lubricating adhesive property at a high temperature and a low temperature by using a synthetic hydrocarbon oil, a lithium-based thickener, and a PMA (Poly Metha-Acrylate) To a grease composition having improved abatement effect.

Description

[0001] The present invention relates to a cold-proof grease composition for reducing noise,

More particularly, the present invention relates to a method for maintaining a lubricating adhesive property at a high temperature and a low temperature by using a synthetic hydrocarbon oil, a lithium-based thickener, and a PMA (Poly Metha-Acrylate) To a grease composition having improved abatement effect.

Generally, grease is used for lubrication of parts of an automobile. When the viscosity of the grease material is high, the noise is reduced. However, the operation is delayed due to a high load during the operation of the parts, thereby causing malfunction. In general, the viscosity of a grease material is low at a high temperature and high at a low temperature, and the viscosity is high at a low temperature as the viscosity is high at a high temperature. In the case of greases used in automobiles exposed to various temperature environments from low to high temperature, the use of viscous grease for noise reduction can cause a working load at low temperature and, in order to maintain operability at low temperatures, There arises a problem that the operating noise is increased at a high temperature and the basic performance and durability of the parts are deteriorated.

Therefore, to improve the performance and durability of the vehicle, it is necessary to develop a grease having little viscosity change depending on the temperature.

In general, there is a method of using an ester base oil, a silicon base oil or a fluorine base oil which is expensive as a base oil of a grease in order to minimize the viscosity change according to the temperature. However, since there are restrictions on usage such as electric parts PAO synthesized base oil, which exhibits excellent effects compared to conventional base oils, is mainly used, and a method of increasing the viscosity at high temperature by using a polymer material such as PIB / PB is being developed. The prior art discloses a grease comprising PMA or a lithium-based thickener in the base oil as shown in US 5,116,522, US 5,108,635. However, such a grease composition has a limitation in maintaining and improving the durability of parts used in automobiles of recent high efficiency and high output, and reducing noise. On the other hand, KR 513,625 discloses PAO as a base oil, PMA as a polymer to be added, and lithium soap as a thickener. However, as compared with the embodiment of the present invention, There has been a limit in improving the durability of the automobile parts under the temperature environment, maintaining the operability and reducing the noise. Korean Patent Registration No. 135414 discloses a synthetic base oil obtained by mixing a poly-alpha-olefin having a high viscosity index and a poly-alpha-olefin having a low viscosity index, a thickener made of lithium composite soap, a PMA- Although a mixed ball joint grease composition has been disclosed, it has a problem in that it has insufficient high-temperature durability in spite of relatively high weight (25-50%) of the PMA-based copolymer and noise-free operation. In order to improve the high temperature durability, an antioxidant or an extreme pressure agent is conventionally added to the grease, but a sufficient effect has not been obtained.

Accordingly, it is an object of the present invention to provide a lubricating oil composition which can prevent deterioration at a high temperature and improve a high-temperature service life of a grease when a synthetic hydrocarbon oil is used instead of an ester oil as a base oil and a lithium- Particularly, the use of a PMA copolymer improves the low-temperature mobility and high-temperature durability as compared with the conventional grease, so that it is not sensitive to temperature change and has an excellent effect of reducing noise.

The present invention is characterized in that a PMA polymer is used instead of PIB / PB in a PAO synthetic base oil. The viscosity of PAO was 100 ° C with a viscosity of 4 ~ 6 cSt. PMA type copolymer was able to minimize viscosity change with temperature by using Asteric type PMA rather than general linear type PMA.

Accordingly, it is an object of the present invention to provide a cold-resistant grease composition for use in noise reduction which uses a synthetic hydrocarbon oil as a base oil and contains a PMA-based copolymer and a lithium-based thickener.

The present invention relates to a composition comprising 50 to 75% by weight of a base oil composed of synthetic hydrocarbon oil;

10 to 30% by weight of a PMA (Poly Metha-Acrylate) copolymer; And

And 10 to 20% by weight of a lithium-based thickener.

The present invention will be described in more detail as follows.

The present invention uses a synthetic hydrocarbon oil instead of an ester oil as a base oil and adds a PMA-based copolymer and a lithium-based thickener to improve compatibility and adhesiveness to various materials including plastics, To a grease composition capable of improving the lubrication life of the application portion in use and ensuring noiseless operation and improved durability.

The base oil that can be used in the present invention is usually a base oil used in a grease. In this case, a base oil which does not affect plastics and rubber is used. For example, a synthetic hydrocarbon oil, a mineral oil oil or a mixture thereof may be used, but preferably a base oil containing a synthetic hydrocarbon oil as a main component is used. As the synthetic hydrocarbon oil, PAO is preferably a poly-alpha-olefin oil or a copolymer of an alpha -olefin and an olefin.

The synthetic base oils preferred in the present invention should have a kinematic viscosity at 100 ° C of 4 to 6 cSt and a pour point at a low temperature of -50 ° C or less. At this time, if the kinematic viscosity is less than 4 cSt, it is easy to evaporate and the heat resistance is insufficient. When the kinematic viscosity is more than 6 cSt, the torque is large and the calorific value becomes large.

The preferred content of the base oil used in the present invention is 50 to 75% by weight, more preferably 58 to 72% by weight. If the content of the base oil is less than 50% by weight, it is too hard to be practically usable to the grease. If the base oil content exceeds 75% by weight, the lubricating oil may have too high lubricity and liquefaction at high temperatures.

On the other hand, the PMA-based copolymer used in the present invention is used for improving the viscosity index and tackiness of the base oil, and is preferably 10 to 30% by weight, more preferably 13 to 24% by weight, By weight. If the amount is less than 10% by weight, the effect of improving the viscosity index or tackiness obtained by blending the PMA-based copolymer is insufficient. If the amount is more than 30% by weight, the viscosity tends to increase rapidly at low temperatures, resulting in malfunctions and increased noise.

The PMA-based copolymer of the present invention uses a copolymer having a vinyl group (-C═C-) or a carbonyl group (-COO-) shown in the following Chemical Formulas 1 to 4 in the molecule.

Formula 1

R ₁ COOR ₂

(2)

R ₃ COOR ₄ COOR ₅

(3)

R ₆ CH = CHR ₇

Formula 4

R ₈ CH = CHR ₉ COOR ₁₀

In the above Chemical Formulas 1 to 4, R ₁ to R ₁₀ represent hydrocarbons, specifically, an aliphatic group, an aromatic group, or a substituted group of a saturated aliphatic group or an unsaturated aliphatic group. Preferably, the PMA-based copolymer of the present invention uses an Asteric type rather than a linear type. The asteric type has a radial or star-shaped structure and, due to its structural characteristics, has excellent viscosity increasing effect, viscosity index increasing effect and low temperature property when it is dissolved in oil. On the other hand, the fact that the PMA-based copolymer has the ability to improve the viscosity index and the stickiness with respect to the base oil means that the viscosity of the base oil containing the PMA copolymer of 20% by weight is filled in the viscometer, It means that there is a viscosity index improvement ability that keeps the calculated value of the index to 200 or more. The kinematic viscosity is measured in accordance with KS M 2014.

On the other hand, a lithium-based thickener is used in the present invention as a thickener of a grease, and it is preferably 10 to 20 wt%, more preferably 12 to 17 wt%, based on the total amount of the grease composition. If the content is less than 10% by weight, the viscosity becomes low at both the high temperature and the low temperature, and if it exceeds 20% by weight, the viscosity becomes too high at both the high temperature and the low temperature to solidify and the lead becomes 200 or less.

A lithium-based thickener suitable for the present invention can be represented by the following chemical formula (5).

Formula 5

(R ₁₁ -COOLi) n

In the formula (5), R ₁₁ is preferably an aliphatic hydrocarbon group having 6 to 20 carbon atoms, and n represents an integer of a fatty acid lithium soap. If the number of carbon atoms is less than 6, the grease becomes less viscous. If the number of carbon atoms exceeds 20, the heat resistance is deteriorated.

The lithium-based thickener is obtained by reacting a lithium hydroxide compound with a fatty acid compound. In order to avoid leaving a reactive fatty acid group, it is preferable to mix the lithium hydroxide and the fatty acid group of the fatty acid compound so as to be approximately equivalent. The lithium hydroxide compound and the fatty acid compound may be reacted in the base oil, or the lithium fatty acid soap mechanical thickener synthesized in advance may be mixed with the base oil. However, the preferred production method is an electron method which is easy to maintain the stability of the grease.

In the grease according to the present invention, additives such as the following extreme pressure additive, antioxidant, and corrosion inhibitor which are conventionally added to the grease may be added.

If necessary, various additives such as a rust inhibitor, a metal deactivator, and a viscosity index improver may be mixed and used.

By using a known extreme pressure agent as the extreme pressure additive, it is possible to improve the load resistance and the extreme pressure property. For example, the following compounds can be used. Examples of the organic metal system include organic molybdenum compounds such as molybdenum dithiocarbamate and molybdenum dithiophosphate, organic zinc compounds such as zinc dithiocarbamate, zinc dithiophosphate and zinc phenate, antimony dithiocarbamate, Organic antimony compounds such as antimony pentachloride and antimony pentachloride, organic selenium compounds such as selenium dithiocarbamate, organic bismuth compounds such as bismuth naphthenate and bismuth dithiocarbamate, iron compounds such as iron dithiocarbamate, , Organotin compounds such as dithiocarbamate and naphthenic acid, organic tin compounds such as tin maleate and dibutyltin sulfide, or organic alkaline compounds of alkali metals and alkaline earth metals, phenates, phosphonates, gold , Silver, titanium, cadmium and the like can also be used as needed. As the sulfur-based compound, sulfide or polysulfide compounds such as dibenzyl disulfide, sulfurized oils, ash-based carbamic acid compounds, thiourea-based compounds, or thiocarbonates can be used.

As the phosphate extreme pressure agent, phosphoric ester compounds such as phosphoric acid esters such as tricoctyl phosphate and tricresyl phosphate, acidic phosphate esters, phosphorous acid esters and acid phosphite esters can be used. In addition, halogen-based extreme pressure agents such as other chlorinated paraffin or solid lubricants such as molybdenum disulfide, tungsten disulfide, graphite, PTFE, antimony sulfide, and boron compounds such as boron nitride can be used. Among these extreme pressure agents, dithiocarbamate-based compounds and dithioate-based compounds can be preferably used. An antioxidant, an ozone deterioration inhibitor, and an antioxidant, which are added to rubber, plastic, lubricating oil or the like as an antioxidant. For example, the following compounds can be used. That is, it is preferable to use a compound selected from the group consisting of phenyl-1-naphthylamine, phenyl-2-naphthylamine, diphenyl-p-phenylenediamine, dipyridylamine, phenothiazine, N-methylphenothiazine, P-phenylenediamine, N, N'-di-sec-butyl-p-phenylenediamine, , And phenolic compounds such as 2,6-di-tert-dibutylphenol.

Examples of the corrosion inhibitor include alkali metal salts such as barium ammonium salts of organic sulfonic acids, zinc, calcium and magnesium, organic sulfonic acid salts of alkaline earth metals, organic carboxylic acid salts, phenates, phosphonate alkyl or alkenyl succinic acid esters , Partial esters of polyhydric alcohols such as alkenyl succinic acid derivatives sorbitan monooleate, hydroxy fatty acids such as oleoyl chocosin, mercapto fatty acids such as 1-mercapto stearic acid, or metal salts thereof High fatty acids such as stearic acid Esters of higher alcohols with higher fatty acids, such as 2,5-dimercapto-1,3,4-thiadiazole, 2-mercaptothiadiazole, etc., (Dithio) -benzimidazolidine, benzimidazole, and the like, or a disulfide-based compound such as 2,5-bis (dodecyldithio) benzoimidazole, or a trisulfonylphenylphosphine Phosphoric acid esters such as, dilauryl can us the like thiocarboxylic acid ester-based compounds such as thio propionate. Nitrite and the like can also be used.

The grease of the present invention has the effect of preventing brittleness (cracking) and prolonging durability without adversely affecting plastic and rubber by using synthetic hydrocarbon oil instead of ester oil as a base oil, and also has mechanical stability by the added lithium thickener The combination of PMA-based copolymer with improved durability and viscosity index of base oil and tackiness improves deterioration at high temperature and greatly improves the high temperature service life of grease and extends the lubrication life of application part at the cryogenic temperature. There is an effect. In addition, low noise and low vibration operation can be ensured in all temperature / humidity conditions that can be exposed to meet the high performance and high efficiency automotive performance.

Hereinafter, the present invention will be described in more detail with reference to the following examples, but the present invention is not limited thereto.

Examples 1 to 5 and Comparative Examples 1 to 7

A base oil, a lithium-based thickener, and a PMA-based copolymer were blended in the composition shown in Table 1 to prepare a light-weight weatherproof grease composition for noise reduction. The base oil shown in Table 1 below was poly-a-olefin oil (viscosity: 4 to 6 cSt at 100 DEG C) as synthetic hydrocarbon oil. The lithium-based thickener is obtained by reacting lithium hydroxide with 12-hydroxystearic acid. Asteric type PMA (Lubrizol, viscosity: 500 to 800 cSt at 100 캜) was used as the PMA type copolymer.

Category (% by weight) Example Comparative Example One 2 3 4 5 One 2 3 4 5 6 7 Synthetic hydrocarbon oil 63.3 71 59 62.2 64.9 73 55.5 66.3 60.3 54.3 56.3 62.1 Methacrylate polymera 22.2 14.5 26.5 21.8 22.8 9.2 32 22.2 22.2 - - - Methacrylate polymer B - - - - - - - - - 24.6 - Methacrylate polymer C - - - - - - - - - 25.5 - Methacrylate polymer D - - - - - - - - - - - 23.4 Li-soap 14.5 14.5 14.5 16 12.5 14.5 14.5 9 21.5 14.5 14.5 14.5

Test Example

The measurement of the blending lead of the base oil was carried out in accordance with ASTM D217.

The apparent viscosity of the grease was measured in accordance with DIN 51810.

The low temperature torque of the grease was performed in accordance with KS M 2130.

The operating noise test of the grease was carried out by applying the grease to the DOOR LATCH parts and comparing the noise of the conventional grease with the invention grease.

Category (% by weight) Example Comparative Example One 2 3 4 5 One 2 3 4 5 6 7 Mixed lead 290 280 285 267 310 295 290 325 245 294 289 295 Apparent viscosity
(25) 2.6 2.3 2.8 2.8 2.4 1.9 3.2 1.7 2.9 2.3 2.5 2.1 Apparent viscosity
(-40) 14.9
13.2 17.2 18.6 13.0 12.4 22.3 11.7 22.0 35.0 40.0 37.0 Low temperature torque
(-40) Activation 2379 2156 2689 2415 2015 1956 3318 1828 3508 5527 6082 5723 rotation 856 795 902 895 752 698 1084 611 1052 1858 2130 2017

Table 2 shows the miscibility of the grease compositions of Examples 1 to 5 and Comparative Examples 1 to 7 and the change in viscosity and the low-temperature torque at room temperature and low temperature. According to the experiment, it can be seen that the viscosity at low temperatures of Examples 1 to 5 does not rise more than room temperature.

division Conventional grease The inventive grease effect Viscosity (pa.s) Room temperature 2.02 2.6 0.58 (29%) Low temperature 5.96 14.9 8.94 (150%) Improve sound Latch locking sound Closed 72.1 67.1 5.0 (6.9%) Open 78.0 75.1 2.9 (3.7%) Actuator lock 71.0 65.2 5.8 (8.1%) Loosening 64.5 60.6 3.9 (6.0%)

The conventional grease used poly-.alpha.-olefin oil as the synthetic hydrocarbon oil and the lithium-based thickener was obtained by reacting lithium hydroxide with 12-hydroxystearic acid. In particular, poly-a-olefin oil having a low viscosity was used for low temperature characteristics. The conventional grease is excellent in low temperature, but has a low viscosity, which causes noise during operation. However, the grease of the present invention has a higher viscosity at room temperature and lower temperature than conventional grease, which is effective in improving operating noise. Table 3 shows comparative measurements of viscosities and operating noises at room temperature and low temperature of the conventional grease and the present grease. The grease of the present invention is expected to have an increased viscosity compared to the conventional grease and an effect of noise reduction due to an increase in viscosity. In addition, it was found that the noise reduction effect of the latching sound and the actuator operating sound was found by applying the improvement to the operating sound by applying to the door latch single product.

Claims (7)

50 to 75% by weight of base oil composed of synthetic hydrocarbon oil;
10 to 30% by weight of a PMA (Poly Metha-Acrylate) copolymer; And
10 to 20% by weight of a lithium-based thickener;
The PMA-based copolymer is an Asteric type having a radial or star-shaped structure and has a kinematic viscosity of 500 to 800 cSt at 100 ° C.
2. The composition according to claim 1, wherein the base oil is an aliphatic hydrocarbon oil and the viscosity at 100 DEG C is 4 to 6 cSt.
3. The composition according to claim 2, wherein the aliphatic hydrocarbon oil is a copolymer of poly-alpha -olefin oil (PAO) or an alpha -olefin oil and an olefin.
delete delete The light-and-heat resistant grease composition for noise reduction according to claim 1, wherein the lithium-based thickener is obtained by reacting a lithium hydroxide compound with 12-hydroxystearic acid.
The composition according to claim 1, further comprising at least one additive selected from the group consisting of an extreme pressure additive, an antioxidant, a corrosion inhibitor, a rust inhibitor, a metal deactivator, and a viscosity index improver, .