Patent Application
20250154426
This application claims the benefit of priority to Korean Patent Application No. 10-2023-0154833, filed in the Korean Intellectual Property Office on Nov. 9, 2023, the entire contents of which are incorporated herein by reference.
The present disclosure relates to a grease composition and a method for preparing the same that improve water washout characteristics, long-term lubricity, low-temperature storage property, and discoloration resistance.
A grease is a semi-solid type of grease used for lubrication optimization of a mechanical element system such as a bearing and a gear, which is a key part for an automobile and an industry. Typically, the grease is composed of a base oil, a thickener, and an additive.
In general, when the grease is used for a long period of time, some of the base oil is separated from the thickener, which may cause a problem in operation of the part. In particular, a loss of the grease applied to a part that may be easily exposed to an external environment, such as a door module, is highly likely to occur because of an inflow of external moisture or the like. In addition, the grease lost because of the inflow of the external moisture may react with and damage a weather strip, a side seal molding, and the like located at a lower portion of a door, causing an additional problem.
Even when a silicone grease with improved water washout characteristics and low-temperature storage property is used to reduce the above-mentioned problem, the problem of the base oil separation during the long-term use may still occur because of poor long-term lubricity. In addition, even a glycol base oil, which has improved water washout characteristics, low-temperature storage property, and long-term lubricity, is difficult to be applied to an indoor part because of unique discoloration thereof.
Therefore, there is a need for research on a grease composition that has not only improved long-term lubricity and water washout characteristics, but also improved low-temperature storage and discoloration resistance to be applied to various parts/environments.
The present disclosure has been made to solve the above-mentioned problems occurring in the prior art while advantages achieved by the prior art are maintained intact.
An aspect of the present disclosure provides a grease composition that has improved long-term lubricity and water washout characteristics to be used in an environment with frequent moisture inflow, and also has improved low-temperature storage property and discoloration resistance to be applied to various parts, and a method for preparing the same.
The technical problems to be solved by the present disclosure are not limited to the aforementioned problems, and any other technical problems not mentioned herein will be clearly understood from the following description by those skilled in the art to which the present disclosure pertains.
According to an aspect of the present disclosure, a grease composition includes a base oil, a thickener, and a styrene-based block copolymer containing ethylene-alpha olefin copolymerization repeating units as a first polymer additive, wherein 1.5 to 15% by weight of the first polymer additive is contained based on a total weight of the grease composition.
According to another aspect of the present disclosure, a method for preparing a grease composition includes stirring a mixture of a base oil, a thickener, and a styrene-based block copolymer containing ethylene-alpha olefin copolymerization repeating units as a first polymer additive at a temperature in a range from 130 to 180° C. (S1), wherein a content of the first polymer additive in the mixture is 1.5 to 15% by weight based on a total weight of the mixture.
Hereinafter, a grease composition and a method for preparing the same will be described in detail such that those skilled in the art may easily implement the same.
The grease composition according to one embodiment of the present disclosure may contain a base oil, a thickener, and a styrene-based block copolymer containing ethylene-alpha olefin copolymerization repeating units as a first polymer additive.
The base oil is the most basic component of the grease composition and is contained to minimize a change in viscosity of grease depending on a temperature. Additionally, the thickener is a component that may be dispersed in the base oil to improve physical properties, such as heat resistance and water resistance, of the grease.
The first polymer additive, as one of core components of the present disclosure, may include the styrene-based block copolymer containing the ethylene-alpha olefin copolymerization repeating units.
The styrene-based block copolymer containing the ethylene-alpha olefin copolymerization repeating units may include at least one selected from a group consisting of a styrene-ethylene-propylene (SEP) copolymer, a styrene-ethylene-butylene (SEB) copolymer, a styrene-ethylene-butylene-styrene (SEBS) copolymer, and a styrene-ethylene⋅propylene-styrene block (SEPS) copolymer, preferably, may include at least one selected from a group consisting of the styrene-ethylene-propylene (SEP) copolymer and the styrene-ethylene-butylene (SEB) copolymer, and more preferably, may include the styrene-ethylene-propylene (SEP) copolymer.
The grease composition of the present disclosure may contain 1.5 to 15% by weight of the first polymer additive based on a total weight of the grease composition. By containing the first polymer additive within the above range, the grease composition simultaneously improves long-term lubricity and water washout characteristics, thereby preventing a damage to a part by suppressing grease separation resulted from an inflow of external moisture and preventing discoloration of the part to prevent deterioration of aesthetics.
The long-term lubricity disclosed in the present disclosure refers to a property of suppressing the base oil from being separated from the thickener. Therefore, when the long-term lubricity is improved, the separation of the base oil from the thickener is suppressed, so that lubricity may not be lowered even when the grease is used for a long period of time. In addition, the water washout characteristics disclosed in the present disclosure refer to a property that the grease is able to stick to the part without being separated therefrom even with the inflow of the external moisture.
The grease composition according to one embodiment of the present disclosure may further contain at least one selected from a group consisting of an olefin copolymer (OCP), a hydrogenated styrene diblock copolymer (HSD), a polyethylene wax (PE wax), and a polypropylene wax (PP wax) as a second polymer additive along with the first polymer additive.
The grease composition of the present disclosure may contain 1.5 to 15% by weight of the second polymer additive based on the total weight of the grease composition. By containing the second polymer additive within the above range, the grease composition may simultaneously improve the long-term lubricity and the water washout characteristics, similar to when the first polymer additive is added. In particular, when the first polymer additive and the second polymer additive are added at the same time, separation resistance (the long-term lubricity) and the water washout characteristics are further improved, so that the grease may not be separated from the part and a loss of the grease resulted from the inflow of the external moisture may be effectively prevented.
The separation resistance disclosed in the present disclosure refers to a property of the grease being adhered to the part and not being separated, that is, a property directly related to long-term separation resistance.
When the first polymer additive and the second polymer additive are added at the same time, a weight ratio of the first polymer additive and the second polymer additive may be 1 to 2:1.
When the weight ratio of the first polymer additive and the second polymer additive is within the above range, both the long-term lubricity and the water washout characteristics may be improved, but when a content of the second polymer additive is excessive compared to a content of the first polymer additive, as the separation resistance (the long-term lubricity) is lowered, the grease may be separated from the part to cause the damage to the part.
The base oil may include at least one selected from a group consisting of a petroleum oil, a silicone base oil, an aliphatic hydrocarbon oil, and an aromatic hydrocarbon oil, preferably, may be at least one selected from a group consisting of a mineral oil, polyalphaolefin (PAO), alkylbenzene, alkyl naphthalene, polyvinyl ether, polyalkylene glycol, polycarbonate, polyol ester, an ethylene alpha olefin copolymer, polybutene, aromatic ester, hindered ester, dibasic ester, a paraffinic petroleum oil, and a naphthenic petroleum oil, and more preferably, may be at least one selected from a group consisting of alkylbenzene and alkyl naphthalene.
The thickener may include a lithium-based thickener. The lithium-based thickener may be obtained by reacting lithium hydroxide with a fatty acid compound, and may include a fatty acid lithium soap chain structure containing an aliphatic hydrocarbon group.
The grease composition of the present disclosure may contain 60 to 90% by weight of the base oil and 2 to 35% by weight of the thickener based on the total weight of the grease composition.
When the content of the base oil is small, the grease may solidify excessively and practicality may be lowered. On the other hand, when the content of the base oil is excessive, the long-term lubricity may be lowered and liquefaction may occur at a high temperature. Additionally, when the content of the thickener is small, viscosity of the grease may be lowered and the grease may be easily separated from the part. On the other hand, when the content of the thickener is excessive, the grease may solidify excessively.
The grease composition according to one embodiment of the present disclosure may further contain, when necessary, at least one selected from a group consisting of an extreme-pressure additive, an antioxidant, a corrosion inhibitor, an anti-wear agent, a metal deactivator, and a viscosity index improver as a general additive. When adding the general additive, the grease composition of the present disclosure may contain 1 to 5% by weight of the general additive based on the total weight of the grease composition.
The extreme-pressure additive may be added to improve load resistance and an extreme-pressure property, and an organic metal-based extreme-pressure additive, a sulfur-based extreme-pressure additive, a phosphoric acid-based extreme-pressure additive, a halogen-based extreme-pressure additive, and the like may be used.
The antioxidant may use an amine-based compound such as phenyl-1-naphthylamine, phenyl-2-naphthylamine, diphenyl-p-phenylenediamine, dipyridylamine, phenothiazine, N-methylphenothiazine, N-ethylphenothiazine, 3,7-dioctylphenothiazine, p,p′-dioctyldiphenylamine, N,N′-diisopropyl-p-phenylenediamine, and N,N′-di-sec-butyl-p-phenylenediamine; a phenol-based compound such as 2,6-di(tert-butyl) phenol; and an organometallic compound thereof.
The corrosion inhibitor may use an ammonium salt of organosulfonic acid; an organic sulfonic acid salt or an organic carboxylic acid salt of alkaline earth metal; hydroxy fatty acids such as oleoyl sarcosine; mercapto fatty acids such as 1-mercapto stearic acid; imidazoles such as thiazoles, 2-(decyldithio)-benzoimidazole, and benzoimidazole; phosphate esters such as tris nonylphenyl phosphite; thiocarboxylic acid esters such as dilauryl thiopropionate, nitrite, and the like.
The anti-wear agent may be phosphoric acid ester, phosphorous acid ester, a phosphoric acid ester amine salt, molybdenum dithiocarbamate, zinc-dialkyldithiophosphate, and the like.
Additionally, the metal deactivator and the viscosity index improver may be used as needed.
A type and a content of the general additive may be controlled based on a purpose and a function of the part for which the grease is to be used.
Next, a method for preparing a grease composition according to another embodiment of the present disclosure will be described in detail.
The method for preparing the grease composition according to one embodiment of the present disclosure may include stirring a mixture of the base oil, the thickener, and the styrene-based block copolymer containing the ethylene-alpha olefin copolymerization repeating units as the first polymer additive at a temperature in a range from 130 to 180° C. (S1), preferably, may include stirring the mixture at a temperature in a range from 140 to 170° C., and more preferably, may include stirring the mixture at a temperature in a range from 150 to 160° C.
By stirring the mixture in the above temperature range, the first polymer additive may be uniformly dispersed within the grease and the long-term lubricity and the water washout characteristics of the grease may be effectively improved.
The styrene-based block copolymer containing the ethylene-alpha olefin copolymerization repeating units may include at least one selected from the group consisting of the styrene-ethylene-propylene (SEP) copolymer, the styrene-ethylene-butylene (SEB) copolymer, the styrene-ethylene-butylene-styrene (SEBS) copolymer, and the styrene-ethylene⋅propylene-styrene block (SEPS) copolymer, preferably, may include at least one selected from the group consisting of the styrene-ethylene-propylene (SEP) copolymer and the styrene-ethylene-butylene (SEB) copolymer, and more preferably, include the styrene-ethylene-propylene (SEP) copolymer.
The mixture may include 1.5 to 15% by weight of the first polymer additive based on a total weight of the mixture. By containing the first polymer additive within the above range, the mixture simultaneously improves the long-term lubricity and the water washout characteristics, thereby preventing the damage to the part by suppressing the grease separation resulted from the inflow of the external moisture and preventing the discoloration of the part to prevent the deterioration of the aesthetics.
Step S1 may include first mixing the base oil with the thickener (S11) and additionally mixing the styrene-based block copolymer containing the ethylene-alpha olefin copolymerization repeating units with the mixture obtained in S11 (S12). More specifically, step S1 may include first mixing the base oil with the thickener (S100), followed by adding Li to the mixture obtained in step S100 to perform a saponification reaction (S110), and additionally mixing the styrene-based block copolymer containing the ethylene-alpha olefin copolymerization repeating units with the mixture in which the saponification reaction was performed in S110 (S120).
In step S110, the saponification reaction may be performed at a temperature in a range from 60 to 100° C., preferably in a range from 70 to 90° C., and more preferably at 80° C. The saponification reaction may be performed by dissolving an acid component of the thickener in the above temperature range and then adding Li.
The method for preparing the grease composition according to one embodiment of the present disclosure may further include cooling the mixture obtained in step S1 to 25° C. (S2) after step S1. A final grease composition product may be prepared through the cooling of the mixture.
In one example, the mixture in step S1 may further contain at least one selected from the group consisting of the olefin copolymer (OCP), the hydrogenated styrene diblock copolymer (HSD), the polyethylene wax (PE wax), and the polypropylene wax (PP wax) as the second polymer additive.
The mixture of step S1 may contain 1.5 to 15% by weight of the second polymer additive based on a total weight of the mixture. By containing the second polymer additive within the above range, the mixture may simultaneously improve the long-term lubricity and the water washout characteristics, similar to when adding the first polymer additive. In particular, when the first polymer additive and the second polymer additive are added at the same time, the separation resistance (the long-term lubricity) and the water washout characteristics are further improved, thereby preventing the grease from being separated from the part and effectively preventing the loss of the grease resulted from the inflow of the external moisture.
Hereinafter, the present disclosure will be described in more detail via Present Examples. However, such Present Examples are only intended to help understand the present disclosure, and the scope of the present disclosure is not limited to such Present Examples in any way.
88% by weight of an alkylbenzene base oil and 8% by weight of the lithium-based thickener were first mixed with each other, then lithium stearate was added to the mixture to perform the saponification reaction at 80° C., then 2% by weight of the first polymer additive was stirred at 150° C. as the polymer additive, then 2% by weight of the general additive was further mixed with the mixture, and then the product was cooled to 25° C. through a homogenization process to prepare a grease composition.
Here, a product with a product name FHL50 (Isu Chemical) was used as the alkylbenzene base oil, a product with a product name Lithium-12-hydroxy-stearat (BAERLOCHER) was used as the lithium-based thickener, a product with a product name Kraton G 1740, as the styrene-ethylene-propylene (SEP) copolymer, was used as the first polymer additive, a product with a product name Lubrizol 2292B, as the corrosion inhibitor, was used as the general additive, and a product with a product name Lubrizol 1395 was used as the anti-wear agent.
It was prepared in the same manner as Present Example 1, except that 87% by weight of the alkylbenzene base oil and 3% by weight of the first polymer additive as the polymer additive were added.
It was prepared in the same manner as Present Example 1, except that 85% by weight of the alkylbenzene base oil and 5% by weight of the first polymer additive as the polymer additive were added.
It was prepared in the same manner as Present Example 1, except that 80% by weight of the alkylbenzene base oil and 10% by weight of the first polymer additive as the polymer additive were added.
It was prepared in the same manner as Present Example 1, except that 7% by weight of the lithium-based thickener, and 1.5% by weight of the first polymer additive and 1.5% by weight of the second polymer additive as the polymer additives were added.
Here, the product with the product name Kraton G 1740, the styrene-ethylene-propylene (SEP) copolymer, was used as the first polymer additive, and a product with a product name Lubrizol 2019, the olefin copolymer (OCP), was used as the second polymer additive.
It was prepared in the same manner as Present Example 5, except that a product with a product name Lubrizol 7306, as the hydrogenated styrene diblock copolymer (HSD), was used as the second polymer additive.
It was prepared in the same manner as Present Example 5, except that a product with a product name Lionchemtech L-C 106, as the polyethylene wax (PE wax), was used as the second polymer additive.
It was prepared in the same manner as Present Example 5, except that a product with a product name Lionchemtech L-C 502, as the polypropylene wax (PP wax), was used as the second polymer additive.
It was prepared in the same manner as Present Example 1, except that 10% by weight of the lithium-based thickener was added and no polymer additive was added.
It was prepared in the same manner as Present Example 1, except that a product with a product name Daelim PB2400, as polybutylene (PB), was used as the first polymer additive.
It was prepared in the same manner as Present Example 1, except that the product with the product name Lubrizol 7306, as the hydrogenated styrene diblock copolymer (HSD), was used as the first polymer additive.
It was prepared in the same manner as Present Example 1, except that 89% by weight of the alkylbenzene base oil and 1% by weight of the first polymer additive as the polymer additive were added.
It was prepared in the same manner as Present Example 1, except that 1.5% by weight of the first polymer additive and 1.5% by weight of the second polymer additive as the polymer additive were added.
Here, the product with the product name Kraton G 1740, as the styrene-ethylene-propylene (SEP) copolymer, was used as the first polymer additive, and a product with a product name Kraton D 1161, as a styrene-isoprene-styrene (SIS) copolymer, was used as the second polymer additive.
It was prepared in the same manner as Comparative Example 6, except that a product with a product name Kraton G 1652, as the styrene-ethylene-butylene-styrene (SEBS) copolymer, was used as the second polymer additive.
It was prepared in the same manner as Comparative Example 6, except that a product with a product name Kraton D SBS, as a styrene-butylene-styrene (SBS) copolymer, was used as the second polymer additive.
It was prepared in the same manner as Comparative Example 6, except that a product with a product name Kuraray LIR, as liquefied isoprene rubber (LIR), was used as the second polymer additive.
It was prepared in the same manner as Comparative Example 6, except that a product with a product name Lubrizol 2006E, as copolymer ester, was used as the second polymer additive.
The water washout characteristics were evaluated at a test temperature of 25° C. In this regard, as a result of the water washout characteristics evaluation, water resistance with a loss rate equal to or smaller than 0.5% by weight was evaluated to be very good, water resistance with a loss rate equal to or smaller than 0.7% by weight was evaluated to be good, water resistance with a loss rate greater than 0.7% by weight was evaluated to be poor, and water resistance with a loss rate equal to or greater than 1.0% by weight was evaluated to be very poor.
As the result of the evaluation, Present Example 1 was found to be good, and Present Examples 2 to 4 were found to be very good. Therefore, it may be seen that, when the first polymer additive is used and the content thereof is equal to or greater than 3% by weight, the water washout characteristics were significantly improved.
In addition, the evaluation results of Present Examples 5 to 8 were also found to be very good. Therefore, it may be seen that, when, along with the first polymer additive, at least one selected from the group consisting of the olefin copolymer (OCP), the hydrogenated styrene diblock copolymer (HSD), the polyethylene wax (PE wax), and the polypropylene wax (PP wax) is further contained, the water washout characteristics were significantly improved.
However, Comparative Example 1 in which no polymer additive was added was evaluated as having very poor water washout characteristics, and Comparative Examples 5 to 8 in which the styrene-isoprene-styrene (SIS) copolymer and the liquefied isoprene rubber (LIR) were used as the second polymer additive were evaluated as having poor water washout characteristics. In addition, Comparative Example 2 in which polybutylene (PB) was used as the first polymer additive and Comparative Example 4 in which the first polymer additive was added in a little amount of 1% by weight were evaluated to be poor.
As the long-term lubricity, a degree (%) of oil separation when the evaluation was performed at 100° C. for 24 hours based on ASTM D6184 (oil separation from lubricating grease) was evaluated. In this regard, as the result of the long-term lubricity evaluation, the oil separation degree equal to or smaller than 0.3% was evaluated as very good, the oil separation degree equal to or smaller than 0.5% was evaluated as good, the oil separation degree greater than 0.5% was evaluated as poor, and the oil separation degree equal to or greater than 1.0% was evaluated as very poor.
As the result of the evaluation, it was found that Present Examples 1 to 8 were all good. In other words, it may be seen that the long-term lubricity was improved when using the first polymer additive.
However, Comparative Example 1 in which no polymer additive was added, and Comparative Examples 5 to 8 using the styrene-isoprene-styrene (SIS) copolymer, the styrene-ethylene-butylene-styrene (SEBS) copolymer, the styrene-butylene-styrene (SBS) copolymer, and the liquefied isoprene rubber (LIR) as the second polymer additive were evaluated as having very poor long-term lubricity. In addition, Comparative Examples 2 and 3 using polybutylene (PB) and the hydrogenated styrene diblock copolymer (HSD) as the first polymer additive were found to have poor long-term lubricity, and Comparative Example 9 using copolymer ester as the second polymer additive was evaluated as having very poor long-term lubricity.
Table 1 below is a table summarizing the water washout characteristics and long-term lubricity evaluation results.
According to one embodiment of the present disclosure, the grease composition and the method for preparing the same that may be applied to the various conditions/parts such as the environment with the frequent moisture inflow by improving all of the long-term lubricity, the water washout characteristics, the low-temperature storage property, and the discoloration resistance by optimizing the type and the content of the polymer additive may be provided.
Hereinabove, although the present disclosure has been described with reference to exemplary embodiments and the accompanying drawings, the present disclosure is not limited thereto, but may be variously modified and altered by those skilled in the art to which the present disclosure pertains without departing from the spirit and scope of the present disclosure claimed in the following claims.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10-2023-0154833 | Nov 2023 | KR | national |
