WO2003099971A1

WO2003099971A1 - Electric discharge machining oil composition

Info

Publication number: WO2003099971A1
Application number: PCT/JP2003/004070
Authority: WO
Inventors: Masahiro Hata; Satoshi Suda; Osamu Hasegawa
Original assignee: Nippon Oil Corporation
Priority date: 2002-05-27
Filing date: 2003-03-31
Publication date: 2003-12-04
Also published as: AU2003221009A1; JP2003342595A

Abstract

An electric discharge machining oil composition, which comprises a base oil comprising a mineral oil and/or a synthetic oil having a kinematic viscosity at 40˚C of 0.5 to 20 mm2/s and, incorporated therein, (A) a compound having two or more of hydroxyphenyl groups and (B) a polymer material having a kinematic viscosity at 40 °C of 30 mm2/s or more and a kinematic viscosity at 100˚C of 10 mm2/s or more and/or a polymer material having a weight average molecular weight of 500 or more. The electric discharge machining oil composition is excellent in machining accuracy and machining rate, exhibits suppressed formation of a tar-like material, is excellent in the ability of letting out machining wastes, and is capable of improving workability and work environment.

Description

Release of the description. Industrial oil composition

[Technical field]

The present invention relates to an electric discharge machining oil composition, and in particular, has excellent basic performances such as machining accuracy and machining speed, can suppress the generation of tar-like substances at the time of electric discharge machining, and has an excellent discharge property of machining waste. The present invention relates to an electric discharge machining oil composition which is excellent and can improve the working environment.

[Background technology]

In the open mouth method, an electrode (copper, graphite, etc.) and a conductive workpiece are opposed to each other in an insulating medium with a small gap of several micron to several tens of microns. When a voltage is supplied in a pulsed manner from a machining power supply through the electrode, a discharge is generated when the distance between the electrode and the workpiece is the interval at which the discharge is started at that voltage, and the workpiece is machined with high precision. Machining speed (machining efficiency) is a measure of how much power can be extracted from the power source. Machining accuracy (irregularities on the machining surface, ie, surface roughness, machining due to the adhesion of burning residue such as oil due to electric discharge) This is one of the basic performances of the discharge port method along with the surface contamination (indicated by the presence or absence of spots).

Since release oil used as an insulating medium has a great effect not only on processing accuracy but also on processing speed, various studies have been conducted so far. For example, in order to improve the processing speed, Japanese Patent Application Laid-Open Nos. Sho 59-1874, 24, Sho 62-27772, and Hei 6-1555165 In each of these publications, it is proposed to incorporate a high molecular weight compound, and in Japanese Patent Application Laid-Open No. 2-76626, it is proposed to incorporate an aromatic compound. However, despite these considerations, an EDM oil that still shows a sufficient acceleration rate has been obtained.

In electric discharge machining, electric discharge occurs instantaneously through the electric discharge machining oil, so that the release oil is locally exposed to a high temperature, and a part of the oil is thermally decomposed. Tar-like substances are formed. Tar-like substances are usually removed by a filter. Generally, tar-like substances produced in such systems are Since it contains fine particles (less than lwm), the requirements for filters are very strict, and the equipment becomes complicated and the work becomes complicated. In addition, this tar-like substance not only deteriorates workability, but also causes the machining surface to be locally uneven, and causes a reduction in machining speed due to the instability of electric discharge due to adhesion to the electrode portion. Become. In addition to the above-mentioned processing accuracy and processing speed, the radiating roe oil is not only capable of discharging the processing chips (dispersibility), the odor due to the evaporation of the release oil, and the stickiness due to scattering in the machine. It also affects various other performances such as deterioration of the work environment.

The present inventors have proposed a release oil which is excellent in various performances as described above (Japanese Patent Application Publication No. 2001-115179). Further improvements are desired.

The present invention has been made in view of such a situation, and its object is to provide, as basic performance, excellent processing accuracy and processing speed, further suppress the generation of tar-like substances, and excel in discharge of processing waste, Another object of the present invention is to provide a release oil composition which can improve workability and work environment. .

[Disclosure of the Invention]

The present invention relates to a base oil comprising mineral oil and Z or synthetic oil and having a kinematic viscosity at 40 ° C. of 0.5 to 20 mm ² Zs, wherein (A) two or more hydroxyphenyl groups are provided. A compound, and (B) a polymer substance having a kinematic viscosity at 40 ° C of 30 mm ² / s or more and a kinematic viscosity at 100 ° C of 10 mm ² / s or more, and Z or weight average molecular weight Is an electrical discharge machining oil composition containing 500 or more high molecular substances. Hereinafter, the present invention will be described in detail.

Examples of the base oil in the electric discharge machining oil composition of the present invention include mineral oil and / or synthetic oil. Mineral oil-based and z- or synthetic-based base oils can be used without any particular limitation as long as they are commonly used as base oils for release oil.

Examples of the mineral oil include, for example, kerosene fraction obtained by distillation of paraffinic or naphthenic crude oil; normal paraffin obtained by extraction operation from kerosene fraction; and paraffinic or naphthenic crude oil. The lubricating oil fraction obtained by distillation is subjected to solvent dewatering, solvent extraction, hydrocracking, solvent dewaxing, contact dewaxing, and water One or more suitable purification treatments, such as denaturation purification, sulfuric acid washing, and white clay treatment, etc .: Immobilized and purified.

Specific examples of synthetic oils include polyolefins (propylene oligomers, isobutylene oligomers, polybutene, 1-octene oligomers, 11-decene oligomers, ethylene-propylene oligomers, etc.) or hydrides thereof. Alkylbenzene, alkylnaphthalene, diester (ditridecyl glutarate, di-2-ethylhexyl adipate, disodecyl adipate, ditridecyl diapate, di-2-ethylhexyl sepacate, etc.), polyol esteranol (trimethylonolepropane caprylate, Trimethylonolepropanepera / legonate, pentaerythritol tonole 2-ethynolehexanoate, pentaerythritol peralgonate, etc.), polyglyconole, silicone oil, jia / lex / leif Air / water, polyether and the like. Among these synthetic oils, hydrogenated propylene oligomers, hydrogenated isobutylene oligomers, and hydrogenated polybutenes are usually called isoparaffins.

As the alkylbenzene, any one can be used. preferable. If the alkylbenzene has less than 8 carbon atoms, the volatility may increase. On the other hand, if the alkylbenzene has more than 40 carbon atoms, the required performance may not be obtained. These alkyl groups may be linear or branched, but are preferably branched alkyl groups from the viewpoint of work safety. The alkylbenzene used may be not only a single structure alkylbenzene but also a mixture of alkylbenzenes having different structures. In the present invention, in addition to using the mineral base oil or the synthetic base oil alone, two or more mineral base oils, or a mixture of two or more synthetic base oils, may be used. Further, a mixture of the above mineral base oil and synthetic base oil may be used. The mixing ratio of two or more base oils in the above mixture is not particularly limited, and can be arbitrarily selected.

In the present invention, from the viewpoint of working environment such as odor, it is preferable to use a base oil having a saturated content of 95% by volume or more, more preferably a base oil having a saturated content of 98% by volume or more. Preferably saturated components 9 9 volume% or more of the base oil, and most preferably the saturated components used 1 0 0 base oil capacity ^_0/0. The term “saturated component” as used herein refers to the value measured by the fluorescence indicator adsorption method (FIA method) of JISK 2536 “Petroleum product one-component test method”. Specific examples of the above-mentioned saturated components and base oils include normal paraffin and isoparaffin.

When normal paraffin and z or isoparaffin are used, their content (total content) is not less than 40% by mass on the basis of the total amount of the composition so as not to adversely affect the working environment due to odor or the like. It is preferably at least 50% by mass, more preferably at least 60% by mass. On the other hand, its content is used to improve the processing speed and processing accuracy (having good surface roughness and no stain on the pressed surface) and to suppress the formation of tar-like substances. The content is preferably 99.85% by mass or less, more preferably 99.5% by mass or less, and most preferably 99.0% by mass or less based on the total amount of the composition.

In the present invention, since the processing speed and the surface roughness can be further improved, it is preferable to use a naphthenic mineral oil and / or alkylbenzene in combination with the base oil having a high content of saturation. However, when these are used in combination, stains may be generated, and among them, alkylbenzene is preferably used from the viewpoint that stains are less likely to occur. Examples of the naphthenic mineral oil include those obtained by appropriately purifying a lubricating oil fraction obtained by distilling the above-described naphthenic mineral oil, and more specifically, those having the following properties are preferable. .

Preferably 1) n-d- M analysis% obtained by method C _N is 4 0 or more, more preferably 4 5 or more, more preferably 5 0 or more.

2) The aniline point is preferably 70 ° C. or lower, more preferably 67 ° C. or lower, even more preferably 65 ° C. or lower.

3) The pour point is preferably at most 130 ° C, more preferably at most 140 ° C, even more preferably at most 45 ° C.

When using naphthenic mineral oil and Z or alkylbenzene, the content (total content) should be 1% by mass or more based on the total amount of the composition in order to increase the processing speed and obtain good surface roughness. preferably, more preferably 3 mass ^_0/0 or more, further It is preferably at least 5% by mass, most preferably at least 7% by mass. On the other hand, in order to suppress the occurrence of spots, the content is preferably 50% by mass or less, more preferably 40% by mass or less, and most preferably 30% by mass, based on the total amount of the composition. It is as follows.

As described above, as the base oil used in the present invention, it is preferable to use a naphthenic mineral oil and / or an alkylbenzene because the working environment such as odor can be further improved, and the processing speed and surface roughness can be improved. Therefore, in the present invention, it is more preferable to use a combination of normal paraffin and / or isoparaffin with naphthenic mineral oil and Z or alkylbenzene so as to satisfy all of the above-mentioned performances, and it is more unlikely to cause spots. From the viewpoint, it is more preferable to use a combination of normal paraffin and / or isoparaffin and alkylbenzene. The total content of the mineral oil and / or the alkylbenzene is preferably at least 0.05, more preferably at least 0.1 with respect to the former content of 1, in order to improve the processing speed and the surface roughness. It is. On the other hand, its content is preferably 0.5 or less, more preferably 0.4 or less, in order to suppress the formation of stains.

The base used in the present invention can be operated at 40 ° C regardless of whether one kind of base oil is used alone or two or more kinds of base oils are used in combination from the viewpoint of fire safety. viscosity 0. and at 5 mm ² / s or more, whereas, Karoe debris exclusion, in order to maintain good for cold却作electrodes such as kinematic viscosity at above 4 0 ° C is 2 0 mm ² / s or less under It is. To ensure the safety of more against fire, kinematic viscosity at above 4 0 ° C is preferably l mm ² / s or more, more preferably 1. 5 mm ² / s or more, whereas, the processing refuse In order to obtain more excellent effects such as easy removal, less occurrence of stains, better cooling of electrodes and the like, and improvement in processing speed, the kinematic viscosity at 40 ° C. , preferably less 1 S nrn ^ Z s, more favorable Mashiku is 1 O mn ^ Z s or less, more preferably no more than 5 mm ² Z s, and most preferably rather is less 3 mm ² / s. When two or more base oils are used in combination, the lower limit of the kinematic viscosity at 40 ° C is preferably 0.5 mm ² / s or more from the viewpoint of fire safety. , more preferably l mm ² / s or more, more preferably not more 1. 5 mm ² / s or more, whereas, the removal of processing refuse is easy, stains hardly occurs, cooling action of such or electrodes In order to obtain more excellent effects such as good oil quality and improved processing speed, the upper limit of the kinematic viscosity at 40 ° C. of each base oil is preferably 2 O mmVs or less. It is preferably at most 15 mm ² / s, more preferably at most 10 mm ² / s, even more preferably at most 5 mm ² Zs, most preferably at most 3 mm ² Zs.

The content of the base oil is preferably at least 40% by mass, more preferably at least 50% by mass, further preferably at least 60% by mass, most preferably at least 70% by mass, based on the total amount of the composition. % Or more. On the other hand, the content of the base oil is preferably 99.85% by mass or less, based on the total amount of the composition, in order to facilitate the removal of processing waste and tar-like substances staying between the poles. It is more preferably at most 99.5% by mass, most preferably at most 99.0% by mass.

The compound (A) having two or more hydroxyphenyl groups used in the present invention is a compound having two or more hydroxyphenyl groups in the molecule. The alkyl group may be substituted with an alkyl group having 1 to 4 carbon atoms. The conjugate having two or more hydroxyphenyl groups used in the present invention is preferably a compound having at least one alkyl group in each hydroxyphenyl group, more preferably a compound having two or more hydroxyphenyl groups. It is. The compound used in the present invention may be a compound having three or more hydroxyphenyl groups.However, since the formation of tar-like substances can be further suppressed, the compound having two hydroxyphenyl groups can be used. It is preferably a compound. As for the plurality of hydroxyphenyl groups, the phenyl groups may be directly bonded to each other, may be bonded via a hydrocarbon group, or may be a bonding group containing an atom other than carbon or hydrogen such as oxygen or sulfur. Good, even though they are combined through. Examples of the binding group containing oxygen and sulfur or sulfur include 1 S—, —oc (= θ), and a combination of these and a hydrocarbon group. Among these bonding groups, the formation of tar-like substances can be further suppressed, so that the group containing oxygen and the group containing sulfur are included. And a group containing oxygen and sulfur, more preferably a group containing oxygen and sulfur.

The compound having two or more hydroxyphenyl groups used in the present invention is preferably a bisphenol compound represented by the following general formula (1).

In the general formula (1), R ¹ R ² , R ³ and R ⁴ each independently represent an alkyl group having 1 to 4 carbon atoms, and R ⁵ , R ⁶ , ¹⁷ and ¹⁸ each represent an individual Shows an α / alkylene group having 1 to 10 carbon atoms.

The alkyl group represented by the above ¹ to! ^ ⁴ may be linear or branched, and specific examples thereof include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, Examples include an isobutyl group, a sec-butyl group, and a tert-butyl group. Of these, a tert-butyl group is preferable because of its excellent effect of suppressing tar-like substances.

The alkylene group represented by R ^{5 to} R ⁸ may be linear or branched, and specific examples thereof include a methylene group, an ethylene group, a propylene group, a butylene group, a pentylene group, and a hexylene group. And alkylene groups such as a heptylene group, an octylene group, a norylene group, and a decylene group (these alkylene groups may be linear or branched). Among them, a methylene group and an ethylene group (dimethylene group, methylmethylene group) are preferable.

Preferred specific examples of the compound having two or more hydroxyphenyl groups used in the present invention are shown below.

0

II

CH _₂ CH ₂ - C one 0- CH ₂ Ten S Although the content of the conjugate having two or more hydroxyphenyl groups used in the present invention is optional, it is usually at least 0.05 mass%, preferably at least 0.1 mass%, based on the total amount of the composition. That is all. On the other hand, the content is usually 10% by mass or less, preferably 5% by mass or less based on the total amount of the composition. When the content of the compound is less than 0.05% by mass based on the total amount of the composition, the effect of suppressing the formation of tar-like substances during electric discharge machining is poor. If the amount exceeds 10% by mass, the consumption of the electrodes increases, which is not preferable. Used as component (B) of the present invention, 4 0 ° C in the kinematic viscosity of 3 0 mm ² / s or more at a kinematic viscosity at 1 0 0 ° C 1 0 mm 2 / s or more polymeric materials, and Z Examples of the high molecular substance having a weight average molecular weight of 500 or more include high-viscosity oils, polymers (polymers), and resins having such properties. Examples of the polymer substance having the kinematic viscosity include mineral oil from which the kerosene fraction and the normal paraffin component have been removed from the base oils described above. Specifically, for example, a lubricating oil fraction obtained by distillation of paraffinic or naphthenic crude oil is subjected to solvent dewatering, solvent extraction, hydrocracking, solvent dewaxing, catalytic dewaxing, hydrorefining, sulfuric acid washing. Purified by appropriately combining one or more purification treatments such as purification and white clay treatment.

Examples of the polymer include a poly-α-olefin (eg, polybutene, polyisobutylene, etc.) or a hydride thereof, a polyamide compound, a polyalkylstyrene, a polyvinyl acetate, a polyalkyl (meth) atalyre. And an ethylene-propylene copolymer or a hydride thereof, and a styrene-maleic anhydride copolymer.

Examples of the resin include a terpene resin and a petroleum resin. Examples of terpene resins include monoterpenes such as hemiterpenes and dipentenes, sesquiterpenes, ditenolepenes, sestatenolepenes, toditeterpenes, tetratenolepenes, polymers of polyterpenes, hydrides thereof, and modified resins thereof. Can be As the petroleum resin, for example, a hydrocarbon fraction having 4 or 5 carbon atoms or a hydrocarbon fraction having 9 or 10 carbon atoms among petroleum cracked fractions is used as a raw material. Resin, or a resin using these fractions as a mixed raw material, or a modified resin thereof, a cyclopentene dicyclopentadiene copolymerized petroleum resin, or a hydride thereof, or a modified resin thereof. be able to.

As the component (B) of the present invention, a polymer (polymer) can be used because it can further improve the calorie precision and the processing speed, and also has an excellent effect of improving workability due to stickiness and the like. ), More preferably poly-α-olefin (for example, polybutene, polyisobutylene, etc.), ethylene-propylene copolymer, polymethacrylate, or a hydride thereof, and polybutene or a hydride thereof is more preferable. More preferred. Further, polybutene or its hydride is also preferable because it does not easily cause stains.

In order to further improve processing accuracy and processing speed, the polymer substance (II) used in the present invention has a kinematic viscosity at 40 ° C of preferably 100 mm ² Zs or more, more preferably 50 Omm ² Roh s or more, more preferably 1000 mm ² / s or more, but most preferably more than 500 Omm ² / s, also 1 00 kinematic viscosity at ° C is preferably 100 mm ² / s or more, more preferably 50 Omm ² / s or more, most preferably 1000 mm ² / s or more. On the other hand, the upper limit of the kinematic viscosity at 40 ° C and 100 ° C is not particularly limited, but the kinematic viscosity at 40 ° C is usually 250,000 mm ² Zs or less, and the working environment such as stickiness is bad. In order not to cause asperity, it is preferably 200,000 mm ² Zs or less, and more preferably 180,000 mni ² Zs or less. For the same reason, the kinematic viscosity at 100 ° C. is 10000 mm ² / s or less, preferably 70000 mm ² / s or less, and more preferably 5000 mm ² / s or less. In the present invention, the polymer substance used as the component (B) has a weight average molecular weight of preferably 1,000 or more, more preferably 2,000 or more, and more preferably, in order to obtain more excellent processing accuracy and processing speed. It has more than 3000, most preferably more than 5000. On the other hand, the upper limit of the weight average molecular weight is not particularly limited, but is usually 50,000 or less, preferably 40,000 or less, more preferably 30,000 or less, and most preferably 10,000 or less.

The content of the polymer substance as the component (B) used in the present invention is based on the total amount of the composition. Preferably 0.1 mass. / ₀ or more, more preferably 0.3% by mass or more, and still more preferably 0.5% by mass. / ₀ or more, most preferably 1 mass. / ₀ or more. On the other hand, the content is preferably 30% by mass or less, more preferably 20% by mass or less, and most preferably 15% by mass or less based on the total amount of the composition. When the content of the component (B) is less than 0.1% by mass based on the total amount of the composition, it is difficult to obtain a sufficient processing speed and a good processing accuracy, while the content is low. 30 mass based on the total amount. When the ratio exceeds / ₀ , workability such as stickiness is poor, and the generation of tar-like substances tends to increase.

The release oil composition of the present invention may contain a known additive, if necessary, for the purpose of further enhancing the performance as a release oil composition.

Specific examples of the additive include an antioxidant, an antifoaming agent, a deterrent, a metal deactivator, an oily agent, an extreme pressure agent, a cleaning dispersant, and a surfactant. The content of these additives is usually 0.05 to 10% by mass based on the total amount of the electric discharge machining oil composition.

[Best Mode for Carrying Out the Invention]

The present invention will be described in more detail with reference to the following Examples and Comparative Examples, but the present invention is not limited thereto.

(Example 1-: I 0 and Comparative Examples 1-2)

According to Table 2-1 and Table 2_2, the electric discharge machining oil composition of the present invention (Example:! ~ 10) and the electric discharge machining oil composition for comparison (Comparative Examples 1 to 2) were respectively obtained. Prepared. Using the obtained EDM oil composition (oil agent), imposition machining was performed under the following machining conditions using an EDM with a servo (Diax EA12E, manufactured by Mitsubishi Electric Corporation). . The performance of the processing oil composition was evaluated by the following evaluation methods (1) to (3). (4) A stickiness test was conducted to evaluate the degree of stickiness of the oil agent. The evaluation results are shown in Table 2-1 and Table 2_2.

(Processing conditions)

Electrode: Copper square bar electrode (5 mm X 5 mm) Work: SKD— 6 1 material (5 cmX 5 cmX lcm)

Reduction allowance (clearance): 0.10 mm

Machining conditions: Machining consisting of the seven processes shown in Table 1 was performed. When the electrode penetration depth reached a predetermined value, the process proceeded to the next step.

Working fluid: The working tank was filled with 12 L of working oil composition.

(1) Processing speed evaluation

The time required for processing (the time until the electrode penetration depth reaches a predetermined position) and the weight change of the workpiece before and after the application were measured, and the processing speed was calculated using the following equation. Machining speed (mg / min) = Weight change of workpiece before and after machining (mg) Time required for Z machining (min)

(2) Surface roughness evaluation

The machining speed test Gyotsu was after the workpiece surface to a surface roughness shape measuring instrument (SURFCOM 5 9 0A _N Tokyo Seimitsu Co., Ltd.) using a surface roughness (Rma x) was measured.

(3) Evaluation of tar generation

After the above-mentioned processing speed test, the state of tar adhesion to the electrode and the state of tar adhesion to the wall surface and the bottom surface of the processing tank were visually observed.

(4) Sticky test

5 mL of the oil agent was placed as a sample on an aluminum dish (10 OmmX 7 Omm), allowed to stand for 24 hours in an open state in a constant temperature bath at 80 ° C, and the degree of stickiness of the sample attached portion was judged by finger touch. Table 2-1

1) Base oil 1: Normal paraffin (saturated content: 100% by volume, kinematic viscosity over 40¾ 1.75mmVs)

2) Base oil ² : isoparaffin (saturation: 99.9% by volume, kinematic viscosity at 40 ° C 1.21 mm ² s)

3) Base oil 3: Alkylbenzene (Kinematic viscosity at 40 ° C 4.32mmVs)

4) Base oil 4: Naphine mineral oil (Kinematic viscosity at 40 ° C 8. OlmmVs.% C _N 55.

(Aniline point 59 ° C, pour point-45 ° C or less)

5) A1

6) 81: polybutylene亍N kinematic viscosity 3850mm ² Zs in kinematic viscosity 160000mm ² Zs 100 ° C in hydride (40 ° C, weight average molecular weight 2900)

7) B2: Polyisobutylene hydride (weight average molecular weight 34000)

8) B3: polymethacrylate (kinematic viscosity at 40C is not measurable due to high viscosity, kinematic viscosity at 100 ° C 1250mm ² s)

) Says ⁴ : Ethylene propylene copolymer hydride (Kinematic viscosity at 40C 10,000 mm ² s

(Kinematic viscosity at 100C 1200mm ² s)

¹⁰ ) B5: Terpene resin (weight average molecular weight 560)

1) B6 raffinic mineral oil (kinematic viscosity at 40 ° C 970mm ² , 's, kinematic viscosity at 100 ° C

Table 2—2

1) to 11) are the same as Table 2-1.

Three From the results shown in Table 2-1 and Table 2-2, when the roast oil composition of the present invention (Examples 1 to 10) was used, all showed excellent processing speed, It can be seen that the surface condition afterward is good, and that no or little stains on the surface of the caroe are generated, and that the formation of tar-like substances and stickiness hardly occur. On the other hand, when a composition containing no component (A) is used (Comparative Example 1), a tar-like substance is generated, and when a composition containing no component (B) is used (Comparative Example 2), It turns out that a sufficient processing speed cannot be obtained.

[Industrial applicability]

By using the electric discharge machining oil composition of the present invention, it is possible to obtain excellent machining accuracy (good surface condition, suppression of generation of stains on the machined surface) and machining speed, and therefore, to perform the discharge roaming efficiently. In addition to this, it is possible to obtain a high-accuracy processed surface with little surface unevenness and almost no stain. In addition, since the generation of tar-like substances is also suppressed, there is no unstable discharge due to adhesion to the electrode portion, and a reduction in the processing speed due to this can be avoided. In addition, the workability and working environment can be further improved because the swarf is easily discharged and the odor due to evaporation and the stickiness due to scattering in the processing machine can be reduced.

Claims

The scope of the claims

1. A base oil composed of mineral oil and Z or synthetic oil and having a kinematic viscosity at 40 ° C of 0.5 to ² Omm ² / ^, (A) a compound having two or more hydroxyphenyl groups, and ( B) A polymer substance with a kinematic viscosity at 40 ° C of 3 Omm ² ^ or more and a kinematic viscosity at 100 ° C of 10 mm ² / s or more, and a polymer substance with a Z or weight average molecular weight of 500 or more Release containing! Oil composition.