JP6699857B2 - Immersion oil for microscope - Google Patents

Description

  The present invention relates to a microscope immersion oil, more specifically, a microscope immersion oil that can maintain low fluorescence for a long period of time and that can be stably produced, In particular, it relates to an immersion oil suitable for a fluorescence microscope.

Immersion oils have been very commonly used in the field of microscopy in the past. The use of the immersion oil not only provides substantially less surface aberration as compared with the case where the immersion oil is not used, but also increases the numerical aperture of the objective lens to increase the magnification of the microscope.
The immersion oil used in this case includes a diarylalkane compound, a specific naphthalene compound and a specific diphenyl compound (see, for example, Patent Document 1), and benzylbutyl phthalate and chlorinated paraffin (for example, patents Reference 2), a microscope immersion oil containing a tricyclodecane derivative or a derivative of a substance having a basic structure of tricyclodecane as a main component (for example, see Patent Document 3), and an ether bond to liquid polybutene (liquid polybutylene). A liquid immersion oil for a microscope containing a liquid aromatic compound (see, for example, Patent Document 4), a liquid oil containing a liquid polyolefin with an aromatic compound (for example, see Patent Document 5), norbornanes, and Immersion oil for a microscope containing a hydrogenated product of a monomer/or norbornene to a tetramer (for example, refer to Patent Document 6), a microscope in which a phthalate ester and paraffins are mixed with a liquid diene copolymer Liquid immersion oils (for example, refer to Patent Document 7) and liquid immersion oils for microscopes in which an α-olefin is mixed with a liquid diene-based copolymer (for example, refer to Patent Document 8) are known.
However, although these immersion oils have almost all the properties required for immersion oils for microscopes, such as refractive index, Abbe number, viscosity, and resolution, their low fluorescence persistence in measurement with a spectrophotometer. It is not enough in terms of sex.

A fluorescence microscope, which is generally used for observing an object that emits fluorescence, irradiates an inspection object with excitation light such as ultraviolet rays and observes the fluorescence emitted by the inspection object, and is used in a wide range of fields such as biology. .. In particular, recently, a technique of a fluorescence microscope that detects a very small amount of fluorescence is being researched, and when detecting such a very weak fluorescence, the immersion oil used in the optical system of the fluorescence microscope emits by ultraviolet excitation. When the fluorescence is large, it becomes noise at the time of detection, which lowers the detection accuracy. Although improvement studies on immersion oil have been carried out in this regard, as mentioned above, the recent needs call for further low fluorescence and stable low fluorescence of the immersion oil. Was not satisfied with.
Immersion oils containing an olefin polymer, a liquid diene polymer, a diarylalkane, and an alkylbenzene have been developed as technologies for improving the persistence of low fluorescence (Patent Documents 9 and 10).

Japanese Patent No. 2623125 U.S. Pat. No. 4,465,621 JP, 9-241214, A JP-A-11-160623 JP, 11-269317, A International Publication No. 2004/090602 JP, 2004-240245, A JP, 2004-240246, A JP, 2008-038001, A JP, 2013-24925, A

When the present inventors further studied the immersion oils disclosed in Patent Documents 9 and 10, the cause is unknown when the compounded diarylalkane is industrially obtained, but the immersion oil may vary depending on the production lot. It was found that there is room for further improvement from the viewpoint of stable production, since the fluorescence of the product may increase.
Therefore, an object of the present invention is to satisfy various properties required for a microscope immersion oil such as a refractive index, an Abbe number, a kinematic viscosity, and a resolving power, and an immersion liquid having a lower fluorescence than a conventional immersion oil for a microscope. It is an object of the present invention to provide an immersion oil for microscopes which is stable and exhibits low fluorescence without being affected by the production lot of diarylalkane.

The inventors of the present invention have made extensive studies in view of the above situation, and as a result, a specific pretreatment-treated diarylalkane, a liquid polyolefin polymer, a liquid diene polymer, and an immersion oil for microscopes containing an alkylbenzene. Then, it discovered that the said subject could be solved. The present invention has been completed based on such findings.
That is, the present invention relates to the following [1] to [12].
[1] At least one pretreated diarylalkane selected from the group consisting of (A) liquid olefin polymer, (B) liquid diene polymer, (C) adsorption treatment, distillation treatment and heat treatment, And (D) alkylbenzene.
[2] The immersion oil for microscopes according to the above [1], wherein the (C) diarylalkane is the pretreated phenylxylylethane and/or the pretreated phenylethylphenylethane.
[3] The immersion oil for microscopes according to the above [1] or [2], wherein the pretreatment is a distillation treatment.
[4] The immersion oil for microscopes according to the above [1] or [2], wherein the pretreatment is an adsorption treatment selected from a clay treatment and an ion exchange resin treatment.
[5] 1 to 30 parts by mass of the liquid diene polymer (B), 40 to 80 parts by mass of the diarylalkane (C), and (D) alkylbenzene to 100 parts by mass of the liquid olefin polymer (A). The immersion oil for microscopes according to any one of the above [1] to [4], containing 2 to 30 parts by mass.
[6] The immersion oil for microscopes according to any one of the above [1] to [5], wherein the liquid olefin polymer (A) has a number average molecular weight of 300 to 25,000.
[7] The immersion oil for microscopes according to any one of [1] to [6] above, wherein the liquid olefin polymer (A) is polybutene.
[8] The immersion oil for microscopes according to any one of [1] to [7], wherein the liquid olefin polymer (A) is a liquid olefin polymer that has been hydrotreated. ..
[9] The immersion oil for microscopes according to any one of the above [1] to [8], wherein the liquid diene polymer (B) has a number average molecular weight of 1,000 to 100,000.
[10] The immersion oil for a microscope according to any one of the above [1] to [9], wherein the liquid diene polymer (B) is polyisoprene.
[11] The immersion oil for microscopes according to any one of the above [1] to [10], wherein the (D) alkylbenzene is 1,3,5-triisopropylbenzene.
[12] The immersion oil for a microscope according to any one of the above [1] to [11], which is an immersion oil for a fluorescence microscope.

  The immersion oil for microscopes of the present invention stably exhibits low fluorescence without being affected by the production lot of raw materials, and is required as a microscope immersion oil such as refractive index, Abbe number, kinematic viscosity, and resolution. Other properties are maintained at a high level. Moreover, since the storage stability is good, the low fluorescence is maintained for a long period of time. Therefore, the immersion oil for microscopes of the present invention is remarkably excellent especially as an immersion oil for fluorescence microscopes.

The immersion oil for microscopes of the present invention comprises at least one liquid selected from the group consisting of (A) liquid olefin polymer, (B) liquid diene polymer, (C) adsorption treatment, distillation treatment and heat treatment. It contains a treated diarylalkane and (D) alkylbenzene.
Hereinafter, each component contained in the microscope immersion oil of the present invention will be described in order.

((A) Liquid olefin polymer)
The liquid olefin polymer as the component (A) used in the present invention is not particularly limited, but the liquid olefin polymer having a number average molecular weight of preferably 300 to 25,000, more preferably 500 to 5,000. Coalescence is used. Examples of these liquid olefin polymers include polyethylene, polypropylene, polybutene, and polyisobutylene, with polybutene being preferred. In addition, these liquid olefin-based polymers may be a single kind, a blend of two or more kinds, or a copolymer thereof.
In addition, in this specification, a number average molecular weight is the value of polystyrene conversion measured by the gel permeation chromatography (GPC) method.

  The method for producing the liquid olefin polymer (A) is not particularly limited and can be produced by a known method, and any of them can be easily obtained industrially. For example, as a method for producing polybutene, there is a method in which butadiene is removed from a C4 fraction produced by naphtha decomposition and polymerization is carried out using an acid catalyst as it is.

As the liquid olefin polymer (A), an olefin polymer subjected to hydrogenation treatment is preferable. By performing the treatment, the fluorescence derived from the (A) liquid olefin polymer in the immersion oil for microscopes can be stably made to have low fluorescence. In this case, stable low fluorescence can be achieved regardless of the hydrogenation rate.
The method for hydrogenation treatment is not particularly limited, and a known hydrogenation treatment for an olefin polymer can be used. Specifically, a method of performing hydrogenation treatment in the presence of a hydrogenation catalyst and hydrogen, and optionally a solvent can be mentioned.

  Examples of the hydrogenation catalyst include nickel-based (Raney nickel, nickel-supported) catalysts, precious metal-based catalysts such as palladium and platinum (palladium black, palladium hydroxide, platinum oxide, palladium-supported, platinum-supported, rhenium-supported, ruthenium). (Supported type) catalyst. Examples of the carrier of the supported catalyst include activated carbon, alumina, silica-alumina, silica, diatomaceous earth, activated clay and the like. Of these, palladium carbon, nickel diatomaceous earth, and ruthenium carbon are preferable from the viewpoint of the hydrogenation treatment effect, that is, the effect of stably obtaining a lower fluorescence immersion oil for microscopes, although not particularly limited thereto.

  The amount of the hydrogenation catalyst used is not particularly limited, but is preferably 0.1 to 50 parts by mass, more preferably 0.5 to 10 parts by mass with respect to 100 parts by mass of the olefin polymer to be subjected to hydrogenation treatment. Parts, more preferably 1 to 10 parts by mass, particularly preferably 1 to 5 parts by mass.

The hydrogenation treatment temperature is not particularly limited, but usually from the viewpoint of controlling the hydrogenation reaction, preferably about 0 to 200°C, more preferably 20 to 180°C, further preferably 50 to 160°C, particularly preferably 70. ~140°C. The hydrogen pressure (which is the hydrogen pressure immediately before the hydrogenation treatment and is hereinafter referred to as “initial hydrogen pressure”) is preferably about 0.01 to 10 MPa, more preferably 0.1 to 5 MPa, and further preferably 0. 0.1 to 3 MPa.
The hydrogenation treatment time is not particularly limited, but is usually preferably about 1 minute to 24 hours, more preferably 5 minutes to 10 hours, and further preferably 10 minutes to 4 hours.

  The solvent that can be optionally used in the hydrogenation treatment is not particularly limited as long as it is an inert solvent for the hydrogenation reaction, and examples thereof include n-pentane, n-hexane, methylpentane, and n-heptane. , Methylhexane, dimethylpentane, n-octane, methylheptane, dimethylhexane, trimethylpentane, dimethylheptane, n-decane and other linear or branched aliphatic hydrocarbons having 5 to 10 carbon atoms; cyclopentane, C5-C10 alicyclic compounds such as methylcyclopentane, cyclohexane, methylcyclohexane, dimethylcyclohexane, ethylcyclohexane, propylcyclohexane; methanol, ethanol, n-propanol, isopropanol, n-butanol, sec-butanol, n- Examples include monoalcohols such as heptanol, 2-heptanol, n-hexanol, and 2-hexanol. Among these, n-hexane, n-heptane, cyclohexane, methylcyclohexane, ethylcyclohexane, and n-butanol are preferable for the convenience of hydrogenation treatment.

(Liquid diene polymer as component (B))
The liquid diene polymer as the component (B) used in the present invention is not particularly limited, but the polystyrene equivalent number average molecular weight measured by gel permeation chromatography (GPC) method is preferably 1,000 to. A liquid diene polymer of 100,000, more preferably 1,000 to 80,000 is used.
Examples of these liquid diene-based polymers include diene homopolymers composed of diene monomers having 4 to 12 carbon atoms, diene copolymers composed of two or more diene monomers having 4 to 12 carbon atoms, and these diene monomers and carbon numbers. There are copolymers with 2 to 22 α-olefin addition polymerizable monomers. For example, butadiene homopolymer (liquid polybutadiene, hydroxyl group-containing liquid polybutadiene), isoprene homopolymer (hydroxyl group-containing liquid polyisoprene), chloroprene homopolymer, butadiene-isoprene copolymer, butadiene-acrylonitrile copolymer, butadiene-2-hexyl acrylate copolymer and the like. Be done.

The preferred liquid diene polymer is a liquid polybutadiene, a butadiene homopolymer such as a hydroxyl group-containing liquid polybutadiene, an isoprene homopolymer such as a hydroxyl group-containing liquid polyisoprene, a copolymer of polybutene and polyisoprene, and more preferably polyisoprene. .. The liquid diene polymer may have a functional group such as a hydroxyl group in the molecule and/or at the terminal of the molecule. Alternatively, it may be a mixture with a liquid diene polymer having no functional group. These liquid diene polymers may be used alone or in combination of two or more.
Further, the liquid diene polymer as the component (B) may be pretreated and then used as one component of the immersion oil for microscopes of the present invention. Examples of the pretreatment include adsorption treatment and heat treatment. It is also possible to combine these pretreatments.

((C) Diarylalkane subjected to at least one pretreatment of adsorption treatment, distillation treatment or heat treatment)
The component (C) used in the present invention is a diarylalkane subjected to at least one pretreatment selected from the group consisting of adsorption treatment, distillation treatment and heat treatment. By using such a pretreated diarylalkane, it is possible to provide a microscope immersion oil that stably exhibits low fluorescence without being affected by the production lot of the diarylalkane. Although the reason why such an effect is obtained is not clear, impurities are generated in the industrially available diarylalkane due to a subtle difference in the production conditions, and the impurities generate other (A) component, (B) component and ( It is presumed that the low fluorescence is deteriorated in the coexistence with the component D). The diarylalkane and the method for pretreating it will be described below.

<diaryl alkane>
The diarylalkane used in the present invention is not particularly limited as long as it is a liquid diarylalkane that is liquid at room temperature and pressure or a mixed diarylalkane that is liquid at room temperature and pressure. The two aryl groups contained in the diarylalkane are preferably aryl groups having 6 to 20 carbon atoms, more preferably aryl groups having 6 to 10 carbon atoms, and having 1 to 10 carbon atoms, preferably 1 to 1 carbon atoms. The alkyl group of 5 may be substituted. The "alkane" portion of the diarylalkane preferably has 1 to 20 carbon atoms, more preferably 1 to 15 carbon atoms, more preferably 1 to 10 carbon atoms, further preferably 1 to 5 carbon atoms, and particularly preferably carbon atoms. The alkanes of the numbers 1 to 3.

As the diarylalkane, for example, diphenylmethane, benzyltoluene, benzylxylene, phenyl-sec-butylphenylmethane, di-sec-butyldiphenylmethane, diphenylethane, phenylethylphenylethane, phenylcumylethane, diisopropylphenylethane, phenyltolylethane, Examples thereof include di-sec-butylphenylethane, di-tert-butylphenylethane, phenylxylylethane, phenyl-sec-butylphenylethane, diphenylpropane, diphenylbutane, ditolylethane, dixylyloctane, and dixylyldecane. Of these, phenylethylphenylethane and phenylxylylethane are preferable.
As phenylethylphenylethane, 1-phenyl-1-(2-ethylphenyl)ethane, 1-phenyl-1-(3-ethylphenyl)ethane, 1-phenyl-1-(4-ethylphenyl)ethane, 1 -Phenyl-2-(2-ethylphenyl)ethane and the like.
As phenylxylylethane, 1-phenyl-1-(2,3-dimethylphenyl)ethane, 1-phenyl-1-(2,4-dimethylphenyl)ethane, 1-phenyl-1-(2,5- Dimethylphenyl)ethane, 1-phenyl-1-(2,6-dimethylphenyl)ethane, 1-phenyl-1-(3,4-dimethylphenyl)ethane, 1-phenyl-1-(3,5-dimethylphenyl) ) Ethane, 1-phenyl-2-(2,3-dimethylphenyl)ethane and the like.
These diarylalkanes can be used alone or as a mixture of two or more if they are liquid at room temperature and pressure.

<Preprocessing>
The pretreatment of the diarylalkane is at least one treatment selected from the group consisting of adsorption treatment, distillation and heat treatment. It is also possible to combine these processes.

Examples of the adsorption treatment agent that can be used for the adsorption treatment include silica, alumina, activated clay, activated carbon, ion exchange resin, and zeolite. The adsorption treatment agents used may be used alone or in combination of two or more.
The silica is not particularly limited, but amorphous silica, crystalline silica, silica hydrate or the like can be used. Examples of commercially available products include silica gel ("FS-0012" manufactured by Organo Corporation).
The alumina is not particularly limited, but amorphous alumina, crystalline alumina, alumina hydrate and the like can be used. Examples of commercially available products include activated alumina ("NKHO-24" manufactured by Sumitomo Chemical Co., Ltd.).
The activated clay is not particularly limited, and naturally-occurring acid clay treated with sulfuric acid is used, but the adsorbed water may be removed by further drying before use. Examples of commercially available products include activated clay ("Galleon Earth NS" manufactured by Mizusawa Chemical Co., Ltd.).

  The activated carbon is not particularly limited, but plant-based, calcareous, or petroleum-based activated carbon can be used. Particularly, lime-based activated carbon made from wood, charcoal, coconut shell charcoal as a raw material, bituminous coal, lignite or the like is preferably used. Examples of commercially available products include “Shirasagi A” manufactured by Nippon EnviroChemicals, Ltd. as activated carbon.

  The ion exchange resin is not particularly limited, and those commercially available in general can be used, but after substituting with a solvent such as methanol in advance, water contained in the resin by a method such as vacuum heating and drying is used. It is preferable to remove it. Commercially available products include ion exchange resins ("Amberlyst 15" and "Amberlyst 16" manufactured by Rohm and Haas, "K2441", "K2461", "K2661" manufactured by Bayer, manufactured by Dow Chemical Co., Ltd. “Dowex 88”, “Dowex MSC-1”, etc.).

  The zeolite is not particularly limited, but those having a structure of faujasite type, chabazite type, mordenite type or the like can be used. Examples of faujasite-type zeolites include natural zeolites such as faujasites, A-type zeolites such as 3A, 4A and 5A, X-type zeolites such as 10X and 13X, and synthetic zeolites such as Y-type. It is also possible to use a combination of the above zeolites. Examples of the chabazite-type zeolite include natural zeolites such as chabazite, gmelinite, erionite, and levinite, and R-type, S-type, or T-type synthetic zeolites. Examples of the mordenite-type zeolite include naturally occurring or synthetic mordenite and clinoptilolite. The zeolite may be a natural product or an artificial synthetic product, but an artificial synthetic product with stable quality is preferable. In the synthetic zeolite, it is possible to change the pore distribution, the Si/Al ratio and the content of other metals by changing the formulation.

  Also, in the pretreatment, regardless of natural zeolite or synthetic zeolite, zeolite modified by calcination, acid contact, base contact, or ion exchange can be used. Suitable ions for ion exchange are alkali metal ions or alkaline earth metal ions. Examples of the alkali metal ion include lithium ion, sodium ion, potassium ion, rubidium ion, and cesium ion. Examples of the alkaline earth metal ion include beryllium ion, magnesium ion, calcium ion, strontium ion, or barium ion.

  The shape of the adsorbent is not particularly limited and may be any shape. The amount of the adsorbent used depends on the content of impurities in the compound before treatment, but is 0.01 to 10 g, preferably 0.05 to 1 g, relative to 1 g of the compound before treatment.

  The temperature at which the solution of the compound is treated with the adsorbent is usually 0 to 100°C, preferably 10 to 40°C.

  The time for treating the solution of the compound with the adsorbent is usually several minutes to several hours, preferably several ten minutes to several hours.

As a method of treating the compound solution with the adsorbent, a predetermined amount of the adsorbent is added to the compound solution and the whole volume is stirred for a predetermined time, and the compound solution is passed through a column filled with the adsorbent. And the like.

A known method can be selected as a method of pretreating the diarylalkane by distillation. For example, simple distillation, steam distillation, continuous multi-stage distillation, batch multi-stage distillation, continuous rectification with a packed column and the like can be mentioned.
The distillation is preferably performed under reduced pressure, and the reflux ratio (reflux amount/distillation amount) is preferably 1/10 or more (reflux amount is 1 or more with respect to distillate amount 10). It is more preferable to set it to 5 to 1/2.
This distillation may be carried out alone, or two or more diarylalkanes may be combined and simultaneously distilled.

In the case of heat treatment of diarylalkane, the time for heat treatment of the solution of the compound is usually from several hours to several days, and depending on the temperature, it is preferably 1 to 2 days. The temperature at which the solution of the compound is heat-treated is usually 50 to 100°C, preferably 60 to 80°C.

((D) Alkylbenzene)
The alkylbenzene of the component (D) used in the present invention is not particularly limited, but the alkyl group of the alkylbenzene is usually one having 1 to 4 carbon atoms, for example, methyl group, ethyl group, isopropyl group, butyl group, etc. Can be raised.
Specific examples include ethylbenzenes such as monoethylbenzene, diethylbenzene, triethylbenzene or tetraethylbenzene, isopropylbenzenes such as monoisopropylbenzene, diisopropylbenzene or triisopropylbenzene, monoisopropyltoluene, diisopropyltoluene or triisopropyltoluene and the like. Isopropyltoluenes may be mentioned.
Among these, 1,3,5-triisopropylbenzene, triethylbenzene and triisopropyltoluene are preferable.

  In the immersion oil for microscopes of the present invention, the liquid olefin polymer as the component (A), the liquid diene copolymer as the component (B), the diarylalkane as the component (C), and the component (D). The blending ratio of the alkylbenzene can be appropriately set, but 1 to 30 parts by mass of the component (B), 40 to 80 parts by mass of the component (C), and 2 to the component (D) per 100 parts by mass of the component (A). 30 parts by mass is preferable. A more preferable blending mass ratio is 2 to 20 parts by mass of the component (B), 50 to 70 parts by mass of the component (C), and 5 to 25 parts by mass of the component (D) with respect to 100 parts by mass of the component (A).

When the blending ratio of the component (A), the component (B), the component (C) and the component (D) is in the above range, the fluorescence of the obtained immersion oil tends to be lower, and the refractive index and Abbe The number, kinematic viscosity, resolution and other properties tend to be good.
Here, other properties required of the immersion oil include non-drying property, appearance, weather resistance, non-corrosion property, contrast, chromatic aberration and transparency.
With the above blending ratio, the immersion oil has low fluorescence, can maintain its properties for a long period of time, and is excellent in other properties.

The order of compounding the components (A), (B), (C), and (D) is not particularly limited, and they can be compounded simultaneously or stepwise in various orders.
The method of blending is also not particularly limited, and usually, a method of blending by stirring and mixing at around room temperature is preferably used.
For the immersion oil for microscopes of the present invention, unless the effect as the original immersion oil is impaired, use the usual additives and compounding agents used for microscope immersion oils such as immersion oils for fluorescence microscopes. You can
The thus obtained immersion oil for microscopes of the present invention can be suitably used as an immersion oil for microscopes, particularly as an immersion oil for fluorescence microscopes.

Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples, but the present invention is not limited to these Examples.
The evaluation of various characteristics of the immersion oil for microscopes was performed using the following methods.

<Evaluation method of immersion oil for microscopes>
Fluorescence intensity The fluorescence microscope used a xenon lamp that emits ultraviolet rays that excite fluorescence as a light source. The excitation light used is U excitation (366 nm), B excitation (488 nm), and G excitation (550 nm). Immersion oils that produce less fluorescence at each excitation are desirable for fluorescence microscopy. The fluorescence intensity of the immersion oil prepared in each example was measured with a spectrofluorometer "F-2500" manufactured by Hitachi, Ltd.
(2) Low fluorescence It was evaluated by the darkness of the background when observed with a fluorescence microscope using the immersion oil.
Good (○): Appeared to be black Black (×): Appeared to be slightly bright (3) Time-dependent change in fluorescence intensity (U excitation)
30 g of the sample was put in a glass bottle, the value of the fluorescence intensity ratio (U excitation) before and after heating at 50° C. for 8 weeks was measured, and evaluated in the following two stages.
Good (∘): Fluorescence intensity ratio value is 2.0 or less Poor (x): Fluorescence intensity ratio value is over 2.0 (4) Refractive index (n23D) and Abbe number (ν23D)
All conformed to JIS K2101. The preferred refractive index range for the microscope immersion oil is 1.5140 to 1.5160, and the preferred Abbe number range for the microscope immersion oil is 38 to 44. The following two grades were used to evaluate whether the refractive index and Abbe number were good or bad. If the refractive index is good, the resolving power is good, and if the Abbe number is good, the chromatic aberration is good.
Good refractive index (◯): Refractive index value of 1.5140 to 1.5160
Poor refractive index (x): Refractive index value is outside the above range Abbe number is good (○): Abbe number value is 38 to 44
Abbe number failure (×): Abbe number value is outside the above range (5) Kinematic viscosity
The kinematic viscosity at 25° C. was measured according to JIS K2283. The range of kinematic viscosity preferable as immersion oil for microscopes is 100 to 1,000 mm ² /sec (25° C.). The goodness and badness of the kinematic viscosity were evaluated in the following two stages.
Good (○): 100 to 1,000 mm ² /sec Poor (x): Outside the above range (6) Non-drying In accordance with JIS C2201 “Electrical Insulating Oil” Evaporation Rate Test, the test was performed at 30° C. for 24 hours, The evaluation was made in the following two stages.
Good (∘): Evaporation amount is less than 1 mass% Poor (x): Evaporation amount is 1% by mass or more (7) Appearance A sample was placed in a clean glass container, and the presence or absence of turbidity was confirmed, and the evaluation was performed in the following two stages.
No turbidity: (○)
Turbid: (x)
(8) Weather resistance
The following two stages depending on the results of the light irradiation test and the heating accelerated deterioration test, which are the evaluation methods described in the following (8-1) and (8-2), and the change in refractive index, Abbe number, and hue before and after the test. It was evaluated by.
Good (○): No change in refractive index, Abbe number and hue.
Poor (x): There was a change in any of the refractive index, Abbe number, and hue.
(8-1) Light Irradiation Test A fixed amount (40±0.5 g) of a sample was put on a Petri dish and the change in the refractive index after irradiation with light for a certain time (24, 72, 120 hours) was measured.
(8-2) Heat accelerated deterioration test (storage stability test)
A fixed amount (40±0.5g) of sample is placed in a 50mL Erlenmeyer flask with stopper, and kept in a constant temperature bath (40, 70°C) for 24 hours, after which the change of refractive index, Abbe number, and hue. Was observed.
(9) Non-corrosive
The presence or absence of corrosiveness was examined by measuring the total acid value (JIS K2501) and the influence on the dye for smear (JIS K2400), and the following two grades were evaluated.
(○): No corrosiveness (×): Corrosive (10) Contrast In a microscope using the immersion oil, by observing a black and white line carved on a black and white plate on which chromium is vapor-deposited, the following two steps are performed. It was evaluated by.
Good (○): clear Poor (x): unclear
(11) Transparency The transmittance (JISK 0115) was used to evaluate the following two levels.
Good (○): 95% or more Poor (x): Less than 95%

<Reference example 1>
Polybutene (manufactured by Idemitsu Kosan Co., Ltd., product name "Polybutene 100R"; number average molecular weight 1000) 100 parts by weight, polyisoprene (Kuraray Co., Ltd., "LIR-30"; number average molecular weight 30000) 12 parts by weight, 32 parts by mass of 1-phenyl-1-(3,4-dimethylphenyl)ethane (lot number PXE-1), 32 parts by mass of 1-phenyl-1-(4-ethylphenyl)ethane (lot number PEBE-1), 18 parts by mass of 1,3,5-triisopropylbenzene were mixed at 25° C. for 10 minutes to prepare a immersion oil for microscopes. The evaluation results are shown in Table 1.
<Reference Examples 2 and 3, Comparative Example 1>
An immersion oil for a microscope was prepared in the same manner as in Reference Example 1 except that the lot of 1-phenyl-1-(3,4-dimethylphenyl)ethane was changed as shown in Table 1. The evaluation results are shown in Table 1.

<Evaluation results of Reference Examples 1 to 3 and Comparative Example 1>
As shown in Table 1, the microscopic immersion oil of Comparative Example 1 using 1-phenyl-1-(3,4-dimethylphenyl)ethane of Lot No. PXE-4 has the other lot Nos. (PXE-1 to PXE). It was found that the low fluorescence was inferior to the immersion oils for microscopes of Reference Examples 1 to 3 using 1-phenyl-1-(3,4-dimethylphenyl)ethane of -3).

Next, the following pretreatment was performed on 1-phenyl-1-(3,4-dimethylphenyl)ethane of lot number PXE-4.
<Pretreatment of diarylalkane>
(1) Pretreatment with adsorbent (silica, activated clay, ion exchange resin) At room temperature (25° C.), about 300 g of 1-phenyl-1-(3,4-dimethylphenyl)ethane of lot number PXE-4 in hexane 300 mL was added and put into a 1 L flask, and 50 g of an adsorbent was added and mixed. After the mixture was stirred at room temperature for 1 hour, solids were removed by filtration. Further, the solvent was distilled off with an evaporator.
(2) Pretreatment by distillation About 300 g of 1-phenyl-1-(3,4-dimethylphenyl)ethane of lot number PXE-4 was put into a 500 mL flask, and a packed column type precision distillation apparatus was set to reduce the pressure to 1 mmHg. .. The kettle temperature was heated to about 125°C, and the distillation was carried out at a reflux ratio of 1/3 and a distillation temperature of 108 to 110°C. After distilling off about 10 g of the initial distillation, about 200 g was collected.
(3) Pretreatment by heat treatment About 300 g of 1-phenyl-1-(3,4-dimethylphenyl)ethane of Lot No. PXE-4 was put in a 300 mL flask, heated at 70°C under air for 48 hours, and then released. Chilled

<Examples 1 to 5>
A immersion oil for a microscope was prepared in the same manner as in Comparative Example 1 except that 1-phenyl-1-(3,4-dimethylphenyl)ethane (lot number PXE-4) was pretreated as shown in Table 1. The evaluation results are shown in Table 1.

<Evaluation results of Examples 1 to 5>
1-Phenyl-1-(3,4-dimethylphenyl)ethane (Lot No. PXE-4) was pretreated in Examples 1 to 5 as immersion oils for microscopes. We were able to achieve low fluorescence that could not have been achieved without it.

<Reference Example 4>
Polybutene (manufactured by Idemitsu Kosan Co., Ltd., product name "Polybutene 100R"; number average molecular weight 1000) 100 parts by weight, polyisoprene (Kuraray Co., Ltd. LIR-30; number average molecular weight 30000) 12 parts by weight, 1-phenyl 32 parts by mass of -1-(3,4-dimethylphenyl)ethane (lot number PXE-1), 32 parts by mass of 1-phenyl-1-(4-ethylphenyl)ethane (lot number PEBE-2), 1,3 , 18 parts by mass of 5-triisopropylbenzene were mixed at 25° C. for 10 minutes to prepare a immersion oil for microscopes. The evaluation results are shown in Table 2.

<Reference Example 5 and Comparative Example 2>
A immersion oil for a microscope was prepared in the same manner as in Reference Example 4 except that the lot of 1-phenyl-1-(4-ethylphenyl)ethane was changed as shown in Table 2. The evaluation results are shown in Table 2.

<Evaluation results of Reference Examples 4 and 5 and Comparative Example 2>
As shown in Table 1 and Table 2, the microscope immersion oil of Comparative Example 2 using 1-phenyl-1-(4-ethylphenyl)ethane of Lot No. PEBE-4 has the other lot Nos. (PEBE-1 to PEBE-1). It was found that the low fluorescence was inferior to the immersion oils for microscopes of Reference Examples 1 and 4 and 5 using 1-phenyl-1-(4-ethylphenyl)ethane of PEBE-3).
Next, 1-phenyl-1-(4-ethylphenyl)ethane of lot number PEBE-4 was pretreated. The pretreatment method is the same as the method described above in <Pretreatment of diarylalkane>.

<Examples 6 to 10>
A immersion oil for a microscope was prepared in the same manner as in Comparative Example 2 except that 1-phenyl-1-(4-ethylphenyl)ethane (lot number PEBE-4) was pretreated as shown in Table 2. The evaluation results are shown in Table 2.

<Evaluation results of Examples 6 to 10>
1-Phenyl-1-(4-ethylphenyl)ethane (Lot No. PEBE-4) was pretreated in each of Examples 6 to 10 to be a immersion oil for microscopes. We were able to achieve low fluorescence that was not possible in some cases.

  From the above, when a diarylalkane was used without a pretreatment selected from adsorption treatment, distillation treatment, and heat treatment, it resulted in poor fluorescence in some lots as immersion oil for microscopes. . This is not preferable from the viewpoint of stable production of immersion oil for microscopes. On the other hand, it was found that good low fluorescence can be realized by subjecting the diarylalkane to a pretreatment selected from adsorption treatment, distillation treatment and heat treatment.

  The immersion oil for microscopes of the present invention is particularly preferably used for fluorescence microscopes.

Claims (9)

A method for producing a microscope immersion oil containing (A) a liquid olefin polymer, (B) a liquid diene polymer, (C) a diarylalkane subjected to a distillation treatment under the following conditions , and (D) an alkylbenzene : Therefore, with respect to 100 parts by mass of the (A) liquid olefin polymer, 1 to 30 parts by mass of the (B) liquid diene polymer, 40 to 80 parts by mass of the (C) diarylalkane, and (D) an alkylbenzene. 2 to 30 parts by mass is blended with the method for producing a microscope immersion oil.
Distillation treatment: Distill under reduced pressure at a reflux ratio of 1/10 or more. The method for producing a microscope immersion oil according to claim 1, wherein the (C) diarylalkane is the pretreated phenylxylylethane and/or the pretreated phenylethylphenylethane. The method for producing a immersion oil for microscopes according to claim 1 or 2 , wherein the (A) liquid olefin polymer has a number average molecular weight of 300 to 25,000. (A) the liquid olefin polymer is a polybutene, a manufacturing method of a microscope immersion oil according to any one of claims 1-3. (A) the liquid olefin polymer is a liquid olefin polymer which has been subjected to hydrogenation treatment, a manufacturing method of a microscope immersion oil according to any one of claims 1-4. The method for producing a microscope immersion oil according to any one of claims 1 to 6 , wherein the (B) liquid diene polymer has a number average molecular weight of 1,000 to 100,000. (B) the liquid diene polymer is a polyisoprene, a method of manufacturing a microscope immersion oil according to any one of claims 1-6. Wherein (D) alkylbenzenes, 1,3,5 triisopropyl benzene, the production method of the microscope immersion oil according to any one of claims 1-7. The microscope immersion oil is a fluorescence microscope immersion oil method of microscope immersion oil according to any one of claims 1-8.