JP6043708B2 - Lubricating oil composition for metal working - Google Patents

Description

  The present invention relates to a lubricating oil composition for metalworking that does not contain chlorine.

Conventionally, various compositions have been used in metal working such as cutting and plastic working, and chlorine-based extreme pressure agents that are excellent in workability improvement effect and inexpensive have been used particularly frequently as metal working fluids.
However, in recent years, lubricating oils containing chlorinated extreme pressure agents have been pointed out as problems such as generation of dioxins during incineration, corrosion and damage of incinerators, and some organochlorine compounds are carcinogenic. It has been reported to have Accordingly, there is a need for the development of metalworking oil that does not contain chlorine. As metal processing oils that do not contain chlorine, those using sulfur base materials such as polysulfide, sulfurized fats and oils, calcium sulfonate, ZnDTP, and phosphorus base materials such as phosphate esters have been conventionally known (the following patent documents). reference).
However, these lubricating oil compositions do not have sufficient machining performance. Due to recent material hardness, high plasticity, and high machining efficiency, the cutting tool life and machining accuracy are reduced, and plastic working However, problems such as material breakage and tool breakage have occurred.

JP-A-6-313182 JP-A-6-330076 Japanese Patent Laid-Open No. 10-226795

  The present invention has been made in view of such circumstances, and provides a non-chlorine-based lubricating oil composition for metal processing that is excellent in processing performance and can be suitably used as a processing oil that can be applied under difficult processing conditions. The purpose is to do.

  As a result of intensive studies on the above problems, the present inventors have found that a lubricating oil composition obtained by blending (A) a polysulfide having a specific structure and (B) a metallic detergent having a specific metal ratio into a lubricating base oil. The present inventors have found that the problems can be solved and have completed the present invention.

  That is, the present invention relates to a metal containing a lubricant base oil, (A) a dialkyl polysulfide in which the number of sulfur crosslinks of 4 or more accounts for 50 mol% or more, and (B) a metal detergent having a metal ratio of 6 or more. It is a lubricating oil composition for processing.

  According to the present invention, there is provided a lubricating oil composition for metalworking that does not contain a chlorine-based extreme pressure agent and has few environmental problems and is excellent in processing performance.

  Hereinafter, the present invention will be described in detail.

  The lubricating oil composition for metal working of the present invention comprises a lubricating base oil, (A) a dialkyl polysulfide in which the number of sulfur crosslinks of 4 or more accounts for 50 mol% or more, and (B) a metal system having a metal ratio of 6 or more. Contains detergent.

  As the lubricating base oil of the lubricating oil composition of the present invention, mineral oil, synthetic oil and fats and oils are used, and these may be a mixture. Mineral oils or synthetic oils consisting of hydrocarbon oils are preferred.

  As mineral oil, for example, a lubricating oil fraction obtained by subjecting crude oil to atmospheric distillation and vacuum distillation is subjected to solvent removal, solvent extraction, hydrocracking, solvent dewaxing, catalytic dewaxing, catalytic dewaxing, hydrogenation. Examples thereof include paraffinic mineral oil or naphthenic mineral oil that is refined by appropriately combining one or more purification treatments such as purification, sulfuric acid washing, and clay treatment.

  Synthetic oils include, for example, propylene oligomer, polybutene, polyisobutylene, 1-octene oligomer, 1-decene oligomer, ethylene and propylene co-oligomer, ethylene and 1-octene co-oligomer, and ethylene and 1-decene. Poly α-olefin (PAO) such as co-oligomer or hydride thereof; isoparaffin; alkyl benzene such as monoalkylbenzene, dialkylbenzene, polyalkylbenzene; alkylnaphthalene such as monoalkylnaphthalene, dialkylnaphthalene, polyalkylnaphthalene; dioctyl adipate, dialkyl Dibasic acid esters such as 2-ethylhexyl adipate, diisodecyl adipate, ditridecyl adipate, di-2-ethylhexyl sebacate, ditridecyl glutarate; Tribasic acid esters such as limellitic acid; polyol esters such as trimethylolpropane caprylate, trimethylolpropane pelargonate, trimethylolpropane oleate, pentaerythritol 2-ethylhexanoate, pentaerythritol pelargonate; polyethylene glycol, polypropylene glycol Polyglycols such as polyoxyethyleneoxypropylene glycol, polyethylene glycol monoether, polypropylene glycol monoether, polyoxyethyleneoxypropylene glycol monoether, polyethylene glycol diether, polypropylene glycol diether, polyoxyethyleneoxypropylene glycol diether; Monoalkyldiphenyl ether, dialkyldiphenyl Ethers, monoalkyl triphenyl ethers, dialkyl triphenyl ethers, tetraphenyl ethers, monoalkyl tetraphenyl ethers, dialkyl tetraphenyl ethers, phenyl ethers such as pentaphenyl ether; silicone oils; fluoroethers such as perfluoroethers, etc. These can be used alone or in combination of two or more.

  Examples of the fat include beef tallow, lard, soybean oil, rapeseed oil, rice bran oil, coconut oil, palm oil, palm kernel oil, hydrogenated products thereof, or a mixture of two or more of these.

Kinematic viscosity at 100 ° C. of the lubricating base oil is preferably 1 to 100 mm ² / s, more preferably 2~80mm ² / s, more preferably 3 to 50 mm ² / s. When the kinematic viscosity at 40 ° C. is less than 1 mm ² / s, the lubricity is lowered, and the working environment is deteriorated due to generation of mist, which is not preferable. On the other hand, if it exceeds 100 mm ² / s, the amount of the oil that adheres to the workpiece and is carried away increases, which is not preferable.

Kinematic viscosity at 40 ° C. of the lubricating base oil is preferably 1 to 500 mm ² / s, more preferably 3~400mm ² / s, more preferably 5 to 50 mm ² / s. If it is less than 1 mm ² / s, the workability is lowered, and if it exceeds 500 mm ² / s, the washability is lowered.

  The content of the lubricating base oil is preferably 70 to 99.8% by mass, more preferably 75 to 95% by mass based on the total amount of the composition.

  The lubricating oil composition of the present invention contains, as component (A), a dialkyl polysulfide compound in which the number of sulfur crosslinks of 4 or more accounts for 50 mol% or more.

Dialkyl polysulfide is a compound represented by the following general formula (1).
R ^1- (S) _n -R ² (1)
(Wherein R ¹ and R ² each represent a linear or branched alkyl group having 1 to 24 carbon atoms, preferably 6 to 18 carbon atoms, and may be the same or different. N represents an integer of 2 to 8) Show.)

Specific examples of R ¹ and R ² in the general formula (1) include methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, sec-butyl group, tert-butyl group, Examples include various pentyl groups, various hexyl groups, various heptyl groups, various octyl groups, various nonyl groups, various decyl groups, and various dodecyl groups.

  Specific examples of the dialkyl polysulfide include di-tert-butyl polysulfide, di-tert-octyl polysulfide, di-tert-nonyl polysulfide, di-sec-octyl polysulfide, di-sec-decyl polysulfide, di-sec-dodecyl polysulfide, Examples include di-sec-hexadecyl polysulfide.

  Component (A) in the lubricating oil composition of the present invention has a content ratio of the dialkyl polysulfide compound in which the number of sulfur crosslinks (n in the above formula (1) in the total dialkyl polysulfide compound is 4 or more) of 50 mol% or more. It is necessary to be a thing, Preferably it is 55 mol% or more, and 60 mol% or more is more preferable. When the content ratio of the dialkyl polysulfide compound having 4 or more sulfur bridges is less than 50 mol%, the extreme pressure performance is not sufficient, which is not preferable. On the other hand, the content ratio of the dialkyl polysulfide compound having 4 or more sulfur bridges is preferably 90% or less, and more preferably 85% or less. When the content ratio exceeds 90 mol%, the stability is lowered, which is not preferable.

  Although there is no restriction | limiting in particular in content of (A) component, 0.1-20 mass% is preferable on the basis of the composition whole quantity, 0.3-15 mass% is more preferable, 0.5-10 mass% is further more preferable. . When the content of the component (A) is less than 0.1% by mass, a sufficient effect as an extreme pressure agent cannot be obtained, and when it exceeds 20% by mass, the oxidation stability of the lubricating oil composition tends to decrease. Each of which is not preferable.

  The lubricating oil composition of the present invention contains a metal detergent having a metal ratio of 6 or more as the component (B).

  Examples of the metal detergent include alkali metal sulfonate or alkaline earth metal sulfonate, alkali metal phenate or alkaline earth metal phenate, and alkali metal salicylate or alkaline earth metal salicylate.

  As the sulfonate, an alkali metal salt or alkaline earth metal salt of an alkyl aromatic sulfonic acid obtained by sulfonating an alkyl aromatic compound having a molecular weight of 300 to 1500, preferably 400 to 700, such as a sodium salt or a potassium salt. , Magnesium salts, and calcium salts, and calcium salts are particularly preferably used.

Specific examples of the alkyl aromatic sulfonic acid include so-called petroleum sulfonic acid and synthetic sulfonic acid.
As said petroleum sulfonic acid, what sulfonated the alkyl aromatic compound of the lubricating oil fraction of mineral oil, what is called mahoganic acid etc. byproduced at the time of white oil manufacture are generally used. Synthetic sulfonic acid can be obtained by, for example, by-producing from an alkylbenzene production plant that is a raw material for detergents, or by alkylating an oligomer of olefins (ethylene, propylene, etc.) having 2 to 12 carbon atoms with benzene. A sulfonated alkylbenzene having a chain or branched alkyl group or a sulfonated alkylnaphthalene such as dinonylnaphthalene is used. The sulfonating agent for sulfonating these alkyl aromatic compounds is not particularly limited, but fuming sulfuric acid or sulfuric anhydride is usually used.

  Phenates include, for example, alkylphenols, alkylphenol sulfides, alkali metal or alkaline earth metal salts of Mannich reactants of alkylphenols, such as sodium, potassium, magnesium and calcium salts. Specific examples include those represented by the following general formulas (2), (3) and (4).

In the general formulas (2), (3) and (4), R ³ , R ⁴ , R ⁵ , R ⁶ , R ⁷ and R ⁸ are each independently 4 to 30 carbon atoms, preferably 6 to 18 carbon atoms. In the formula, M ¹ , M ² and M ³ each represent an alkaline earth metal, preferably calcium or magnesium, and x represents 1 or 2.

Specific examples of the alkyl group represented by R ³ , R ⁴ , R ⁵ , R ⁶ , R ⁷ and R ⁸ are butyl group, pentyl group, hexyl group, heptyl group, octyl group, respectively. , Nonyl group, decyl group, undecyl group, dodecyl group, tridecyl group, tetradecyl group, pentadecyl group, hexadecyl group, heptadecyl group, octadecyl group, nonadecyl group, icosyl group, heicosyl group, docosyl group, tricosyl group, tetracosyl group, pentacosyl group Group, hexacosyl group, heptacosyl group, octacosyl group, nonacosyl group, triacontyl group and the like. These may be linear or branched. These may also be primary alkyl groups, secondary alkyl groups or tertiary alkyl groups.

  Examples of the salicylates include alkali metal salts or alkaline earth metal salts of alkyl salicylic acid such as sodium salt, potassium salt, magnesium salt and calcium salt. Specific examples include compounds represented by the following general formula (5).

In the general formula (5), R ⁹ represents a linear or branched alkyl group having 4 to 30 carbon atoms, preferably 6 to 18 carbon atoms, and M ⁴ represents an alkaline earth metal, preferably calcium or magnesium.

Specific examples of the alkyl group represented by R ⁹ include butyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl, undecyl, dodecyl, tridecyl, tetradecyl, Examples include pentadecyl group, hexadecyl group, heptadecyl group, octadecyl group, nonadecyl group, icosyl group, heicosyl group, docosyl group, tricosyl group, tetracosyl group, pentacosyl group, hexacosyl group, heptacosyl group, octacosyl group, nonacosyl group, triacontyl group, etc. These may be linear or branched. These may also be primary alkyl groups, secondary alkyl groups or tertiary alkyl groups.

  Alkaline earth metal sulfonates, alkaline earth metal phenates, and alkaline earth metal salicylates include the above alkyl aromatic sulfonic acids, alkylphenols, alkylphenol sulfides, Mannich reactants of alkylphenols, alkylsalicylic acid, etc. Or it reacts with alkaline earth metal bases such as calcium alkaline earth metal oxides and hydroxides, or once is converted to an alkali metal salt such as sodium salt or potassium salt and then substituted with alkaline earth metal salt, etc. Neutral (normal salt) alkaline earth metal sulfonate, neutral (normal salt) alkaline earth metal phenate and neutral (normal salt) alkaline earth metal salicylate obtained by: neutral alkaline earth metal sulfonate, neutral Alkaline earth metal phenate Basic alkaline earth metal sulphonates, basic alkaline earth metal sulfonates, basic alkaline earth metal sulfonates obtained by heating excess alkaline earth metal salts and alkaline earth metal bases in the presence of water, A basic alkaline earth metal salicylate; or in the presence of a neutral alkaline earth metal sulfonate, a neutral alkaline earth metal phenate and a neutral alkaline earth metal salicylate; Overbased (superbasic) alkaline earth metal sulfonates, overbased (superbasic) alkaline earth metal phenates and overbased (superbasic) alkaline earth metals obtained by reacting with boric acid Salicylates are also included.

The metal ratio of the component (B) metal detergent must be 6 or more, preferably 6.5 or more, and more preferably 7 or more. When the metal ratio is less than 6, workability becomes insufficient, which is not preferable.
The metal ratio here is represented by the valence of metal element × metal element content (mol) / soap group (that is, group such as alkyl salicylic acid group) content (mol). The alkali metal or alkaline earth metal content relative to the alkyl salicylic acid group or alkyl sulfonic acid group content in the alkali metal or alkaline earth metal detergent is shown.

  The metal-based detergent is preferably an alkaline earth metal-based detergent from the viewpoint of increasing the metal ratio. Among alkaline earth metal detergents, alkaline earth metal sulfonate is more preferable, and calcium sulfonate is particularly preferable from the viewpoint of processability.

Although the total base number of (B) component does not have a restriction | limiting in particular, It is preferable that it is 50-500 mgKOH / g, More preferably, it is 100-450 mgKOH / g. When the total base number is less than 50 mgKOH / g, the lubricity improvement effect tends to be insufficient. On the other hand, those whose total base number exceeds 500 mgKOH / g are very difficult to manufacture and difficult to obtain. It is not preferable.
The total base number referred to here is JIS K 2501 “Petroleum products and lubricants—Test method for neutralization number”. The total base number [mgKOH / g] by the perchloric acid method measured according to the above.

Although there is no restriction | limiting in particular in content of (B) component, it is preferable that it is 0.1-10 mass% on the basis of the composition whole quantity, More preferably, it is 0.2-8 mass%, More preferably, it is 0.00. 5 to 5% by mass.
When the content of the component (B) is less than 0.1% by mass, the effect of improving machining efficiency and tool life tends to be insufficient, and when it exceeds 10% by mass, the stability of the metalworking oil composition is lowered. In this case, precipitates tend to be generated, which is not preferable.

  Further, the lubricating oil composition for metal working of the present invention may contain conventionally known additives other than the above-described components (A) and (B) as necessary. Examples of such additives include non-chlorine extreme pressure agents other than component (A); metallic detergents other than component (B); wetting agents such as diethylene glycol monoalkyl ether; acrylic polymers, paraffin wax, microwax, Film forming agents such as slack wax and polyolefin wax; water displacement agents such as fatty acid amine salts; solid lubricants such as graphite, graphite fluoride, molybdenum disulfide, boron nitride, polyethylene powder; amines, alkanolamines, amides, carboxylic acids , Carboxylate, sulfonate, phosphoric acid, phosphate, partial esters of polyhydric alcohol, etc .; metal deactivators such as benzotriazole, thiadiazole; methyl silicone, fluorosilicone, polyacrylate, etc. Antifoaming agent; alkenyl succinimide, benzylamine Ashless dispersants such as polyalkenyl amines polyaminoamide; and the like. The content when these known additives are used in combination is not particularly limited, but the amount is such that the total content of these known additives is 0.1 to 10% by mass based on the total amount of the lubricating oil composition. It is preferable to add. It is preferable that chlorine is not substantially contained, and the chlorine element content is 10 mass ppm or less, particularly 1 mass ppm or less.

The kinematic viscosity of the lubricating oil composition for metalworking of the present invention is not particularly limited, but the kinematic viscosity at 40 ° C. is preferably 500 mm ² / s or less from the viewpoint of easy supply to the machined part, and 450 mm ² / s It is more preferably s or less, even more preferably 400 mm ² / s or less, and particularly preferably 50 mm ² / s or less. On the other hand, the kinematic viscosity at 40 ° C. is preferably 1 mm ² / s or more, more preferably 3 mm ² / s or more, and further preferably 5 mm ² / s or more.

  Since the lubricating oil composition for metal working of the present invention is excellent in processing performance such as processing efficiency and tool life, and handling properties, it can be suitably used in a wide range of applications in the metal working field. The metal processing here is not limited to cutting / grinding, but broadly means general metal processing. Moreover, the lubricating oil composition for metal working of the present invention can be applied not only to metal processing by a normal oil supply method but also to cutting / grinding processing (MQL processing) with a very small amount of oil supply.

  Specific examples of metal processing include cutting, grinding, rolling, forging, pressing, drawing, rolling, and the like. Among these, the lubricating oil composition for metal working of the present invention is very useful for applications such as cutting, grinding, and rolling.

  EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples.

(Examples 1-3 and Comparative Examples 1-7)
Table 1 shows compositions in which an additive is blended with a lubricating base oil. The addition amount (% by mass) of each additive is based on the total amount of the lubricating oil composition.
(A1) Di-tert-octyl polysulfide (sulfur content: 33.5 mass%, abundance ratio of 4 or more sulfur bridges: 35 mol%), (a2) di-tert-octyl polysulfide (sulfur content: 31 mass%, (A3) di-tert-octyl polysulfide (sulfur content: 20% by mass, abundance ratio of 4 or more sulfur bridges: 35 mol%) is a commercial product. .
(A1) Di-tert-octyl polysulfide (sulfur content: 37 mass%, abundance ratio of 4 or more sulfur bridges: 70 mol%), (A2) di-tert-octyl polysulfide (sulfur content: 37 mass%, sulfur cross-linking) (A3) di-sec-dodecyl polysulfide (sulfur content: 26 mass%, abundance ratio of sulfur bridge number 4 or more: 55 mol%) is (a1), (a2). ) And (a3) are fractions obtained by separating portions having a high degree of sulfur crosslinking with a silica gel chromatograph.
About each obtained composition, processing performance was evaluated by the tapping test shown below. The results are shown in Table 1.

(Tapping test)
In order to evaluate the performance against tool wear, the tapping energy efficiency E with respect to the standard oil was measured under the following processing conditions for the lubricating oil compositions of Examples 1 to 3 and Comparative Examples 1 to 7, and the cutting performance evaluation by this test was performed. Went.
・ Work material: S25C
・ Tool diameter: 8mm
・ Tap pitch: 1.25mm
-Tap rake angle: 10 degrees-Tap biting angle: 1.5 degrees-Tap pilot hole diameter: 7.0 mm
・ Rotation speed: 360rpm
・ Number of processing: 1 hole ・ Standard oil: DIDA (diisodecyl adipate)
-Supply oil amount: 9.0 ml / min

  The tapping energy efficiency E is defined by tapping energy efficiency E (%) = (tapping energy when using a comparative standard oil) / (tapping energy when using an oil composition).

  The lubricating oil composition of the present invention is useful because it does not contain a chlorine-based extreme pressure agent, has few environmental problems, is easy to handle, and can improve machining efficiency and tool life.

Claims (2)

Lubricating oil base oil, (A) di-tert-octyl polysulfide or di-sec-dodecyl polysulfide in which the number of sulfur crosslinks of 4 or more accounts for 50 mol% or more, and (B) metal-based cleans with a metal ratio of 6 or more Lubricating oil composition for metal working containing an agent.   The metal processing lubricant composition according to claim 1, wherein the metal-based detergent is calcium sulfonate.