Liquid immersion oil for microscope

Abstract

The present disclosure addresses the problem of providing a liquid immersion oil for a microscope, the liquid immersion oil exhibiting low corrosivity against plastic materials and satisfying refractive index properties, Abbe number properties, and kinematic viscosity properties. A liquid immersion oil for a microscope according to the present disclosure contains a compound represented by formula (1), an aromatic compound, and a polyol.　Formula (1): (R1-CO-O-R2)p-X-(R3)q

Description

Microscope immersion oil

[0001] FIELD OF THE DISCLOSURE The present disclosure relates to immersion oils for microscopes.

[0002] Immersion oil is commonly used in the field of microscopy. The use of immersion oil not only results in substantially less spherical aberration than when immersion oil is not used, but also allows the numerical aperture of the objective lens to be increased, thereby improving the resolution of the microscope. For example, Patent Document 1 discloses an immersion oil for microscopes that can achieve this.

[0003] Japanese Patent Application Laid-Open No. 2008-038001

[0004] The present disclosure relates to an immersion oil for microscopes comprising a compound represented by formula (1), an aromatic compound, and a polyol.

[0005] Immersion oils for microscopes will be described in detail below. In this specification, the use of "to" means that the numerical values ​​before and after the symbol "to" are included as lower and upper limits. In this specification, each component may be used singly or in combination of two or more substances corresponding to the component. Here, when two or more substances for each component are used in combination, the content of that component means the total content of the substances used in combination, unless otherwise specified.

[0006] The microscope immersion oil of the present disclosure contains the compound represented by formula (1), an aromatic compound, and a polyol, and therefore exhibits low corrosion resistance to plastic materials and satisfies the refractive index, Abbe number, and kinematic viscosity characteristics required of microscope immersion oil.

[0007] Below, each component that may be contained in the microscope immersion oil will be described in detail.

[0008] <Compound Represented by Formula (1)> The microscope immersion oil contains a compound represented by formula (1) (hereinafter also referred to as the "specific compound"). The specific compound is preferably a liquid compound. The liquid compound is a compound that is in a liquid state at room temperature (25°C).

[0009] Formula (1) (R １ -CO-O-R ２ ) ｐ -X-(R３ ) ｑ

[0010] In formula (1), R １ represents an alkyl group having a mercapto group (-SH, thiol group). The alkyl group having a mercapto group may be linear, branched, or cyclic, and is preferably linear or branched. The number of carbon atoms in the alkyl group having a mercapto group is preferably 1 to 10, more preferably 1 to 5, and even more preferably 1 to 3. The number of mercapto groups in the alkyl group having a mercapto group is preferably 1 to 5, more preferably 1 to 3, and even more preferably 1.

[0011] In formula (1), R ２ represents a single bond or an alkylene group. The alkylene group may be linear, branched, or cyclic, and is preferably linear. The alkylene group preferably has 1 to 5 carbon atoms, more preferably 1 to 3 carbon atoms, and even more preferably 1 carbon atom.

[0012] In formula (1), R ３ represents a hydrogen atom or an alkyl group. The alkyl group may be linear, branched, or cyclic, and is preferably linear. The alkyl group preferably has 1 to 5 carbon atoms, more preferably 1 to 3 carbon atoms, and even more preferably 1 or 2 carbon atoms.

[0013] In formula (1), X represents a carbon atom or a group represented by formula (A), and X is preferably a carbon atom.

[0014] In formula (A), * represents a bonding position. When X represents a carbon atom, p represents n, q represents 4-n, and n represents 3 or 4. When X represents a group represented by formula (A), p represents m, q represents 6-m, and m represents 5 or 6.

[0015] Multiple R １ may be the same or different, and are preferably the same. ２ may be the same or different, and are preferably the same. ３may be the same or different from each other. １ -CO-O-R ２ ) are preferably the same as each other.

[0016] Examples of the specific compound include the following compounds.

[0017]

[0018] The molecular weight of the specific compound is preferably 100 to 2,000, more preferably 300 to 600.

[0019] The specific compound may be used alone or in combination of two or more. The content of the specific compound is preferably 1.0 to 90.0 mass%, more preferably 2.0 to 80.0 mass%, based on the total mass of the microscope immersion oil. The content of the specific compound in which X is a carbon atom and n is 4 is preferably 1.0 to 90.0 mass%, more preferably 10.0 to 85.0 mass%, based on the total mass of the microscope immersion oil, and from the viewpoint of more excellent Abbe number characteristics, even more preferably 30.0 to 58.0 mass%. The content of the specific compound in which X is a carbon atom and n is 3 is preferably 1.0 to 90.0 mass%, based on the total mass of the microscope immersion oil, and from the viewpoint of more excellent Abbe number characteristics, even more preferably 2.0 to 85.0 mass%, even more preferably 30.0 to 70.0 mass%.

[0020] <Aromatic Compound> The microscope immersion oil contains an aromatic compound. An aromatic compound is an organic compound having an aromatic ring. Examples of the aromatic ring include an aromatic hydrocarbon ring and an aromatic heterocycle. The aromatic ring may be either a monocyclic ring or a fused ring, with a monocyclic ring being preferred. The aromatic compound preferably has 1 to 5 aromatic rings, more preferably 1 to 3, and even more preferably 1 or 2. Examples of aromatic hydrocarbon rings include a benzene ring, a naphthalene ring, an azulene ring, an anthracene ring, a phenanthrene ring, and a pyrene ring, with a benzene ring being preferred. Examples of aromatic heterocycles include a furan ring, a thiophene ring, an oxazole ring, a pyrrole ring, a pyridine ring, a pyridazine ring, a pyrimidine ring, a pyrazine ring, a triazine ring, an oxadiazole ring, a triazole ring, an imidazole ring, a pyrazole ring, a thiazole ring, an indole ring, and an indazole ring, with a pyridine ring or a thiophene ring being preferred. The aromatic compound is preferably a liquid aromatic compound. A liquid aromatic compound is an aromatic compound that is in a liquid state at room temperature (25°C).

[0021] The aromatic compound is preferably selected from the group consisting of aromatic compounds having a hydroxy group, aromatic compounds having a sulfur atom or a nitrogen atom, and aromatic compounds having two or more aromatic rings, more preferably selected from the group consisting of aromatic compounds having a hydroxy group, aromatic compounds having a sulfur atom, and aromatic compounds having two or more aromatic rings, and even more preferably selected from the group consisting of compounds represented by formula (2), compounds represented by formula (3), and compounds represented by formula (4).

[0022] The aromatic compound having a hydroxy group is an organic compound having a hydroxy group and an aromatic ring. The number of hydroxy groups in the aromatic compound having a hydroxy group is preferably 1 to 5, more preferably 1 to 3, and even more preferably 1. The hydroxy group in the aromatic compound having a hydroxy group may be either a non-phenolic hydroxy group or a phenolic hydroxy group.

[0023] The aromatic compound having a hydroxy group is preferably a compound represented by formula (2).

[0024] Formula (2) Ar １ - (L １ -OH) ｖ

[0025] In formula (2), Ar １ represents an aromatic hydrocarbon ring. The aromatic hydrocarbon ring has the same meaning as the aromatic hydrocarbon ring contained in the aromatic compound described above, and preferred embodiments are also the same.

[0026] In formula (2), L １ has at least one -CH ２ represents an alkylene group which may be substituted with -O-. The alkylene group may be linear, branched, or cyclic, and is preferably linear. The alkylene group preferably has 1 to 10 carbon atoms, more preferably 1 to 6 carbon atoms, and even more preferably 1 to 4 carbon atoms. L １ Examples of the group include —O—CH ２ --, --O-CH ２ CH ２ -O-CH ２ CH ２ -, -CH ２ -, -CH ２ CH ２ -, -CH ２ CH ２ CH ２ -, -CH ２ CH (CH ３ )- or a combination thereof is preferred, and —O—CH ２ --, --O-CH ２ CH ２ -O-CH ２ CH ２ - is more preferred, and -O-CH ２ - is more preferred. １ If there are multiple L １ may be the same or different from each other.

[0027] In formula (2), v represents 1 or 2. Preferably, v is 1.

[0028] Examples of aromatic compounds having a hydroxy group include the following compounds: Furthermore, examples of aromatic compounds having a hydroxy group include methyl salicylate and salicylic acid.

[0029]

[0030] The aromatic compound having a sulfur atom or a nitrogen atom is an organic compound having a sulfur atom or a nitrogen atom and an aromatic ring. The aromatic compound having a sulfur atom or a nitrogen atom may have both a sulfur atom and a nitrogen atom. When the aromatic compound having a sulfur atom or a nitrogen atom has a sulfur atom, the number of sulfur atoms is preferably 1 to 3, and more preferably 1 or 2. When the aromatic compound having a sulfur atom or a nitrogen atom has a nitrogen atom, the number of nitrogen atoms is preferably 1 to 3, and more preferably 1 or 2.

[0031] The aromatic compound having a sulfur atom or a nitrogen atom is preferably a compound represented by formula (3).

[0032] Formula (3) Ar ２ - (L ２ -S-R ４ ) ｗ

[0033] In formula (3), Ar ２ represents an aromatic hydrocarbon ring. The aromatic hydrocarbon ring has the same meaning as the aromatic hydrocarbon ring contained in the aromatic compound described above, and preferred embodiments are also the same.

[0034] In formula (3), L ２ represents a single bond or an alkylene group. The alkylene group is the same as the above-mentioned R ２ The meaning and preferred embodiments are also the same as those of the alkylene group represented by the following formula: ２ is preferably a single bond. ２ If there are multiple L ２ may be the same or different from each other.

[0035] In formula (3), R ４ has at least one -CH ２represents a monovalent aliphatic hydrocarbon group which may be substituted with -COO-. The monovalent aliphatic hydrocarbon group may be either a monovalent saturated aliphatic hydrocarbon group or a monovalent unsaturated aliphatic hydrocarbon group. The monovalent aliphatic hydrocarbon group preferably has 1 to 10 carbon atoms, more preferably 1 to 5 carbon atoms, and even more preferably 1 to 3 carbon atoms. The monovalent aliphatic hydrocarbon group may be a single bond, -CH ２ -, -CH ２ -CH=CH-, -CH ２ -COO-CH ３ or a combination thereof is preferred, and —CH ２ -COO-CH ３ is more preferred. ４ If there are multiple R ４ may be the same or different from each other.

[0036] In formula (3), w represents 1 or 2. Preferably, w is 1.

[0037] Examples of aromatic compounds having a sulfur atom or a nitrogen atom include the following compounds:

[0038]

[0039] An aromatic compound having two or more aromatic rings is a compound having two or more aromatic rings. The aromatic ring has the same meaning as the aromatic ring of the aromatic compound described above, and the preferred embodiments are also the same. The number of aromatic rings in the aromatic compound having two or more aromatic rings is preferably 2 to 5, and more preferably 2 or 3.

[0040] As the aromatic compound having two or more aromatic rings, a compound represented by formula (4) is preferred.

[0041] Formula (4) Ar ３ -L ３ -Ar ４

[0042] In formula (4), Ar ３ and Ar ４each independently represents an aromatic hydrocarbon ring which may have a substituent. The aromatic hydrocarbon ring which may have a substituent has the same meaning as the aromatic hydrocarbon ring of the aromatic compound described above, except that it may have a substituent, and the preferred embodiments are also the same. Examples of the substituent include a halogen atom, an alkyl group, an aryl group, an alkoxy group, an oxyaryl group, a benzyloxy group, an acyl group, an aldehyde group, a carboxy group, a hydroxy group, and a group formed by combining these groups. An alkyl group is preferred, and an alkyl group having 1 to 3 carbon atoms is more preferred.

[0043] In formula (4), L ３ has at least one -CH ２ represents a divalent aliphatic hydrocarbon group which may be substituted with —O— or —COO—, or —O—. ３ represents the above-mentioned divalent aliphatic hydrocarbon group or -O-. The above-mentioned divalent aliphatic hydrocarbon group may be either a divalent saturated aliphatic hydrocarbon group or a divalent unsaturated aliphatic hydrocarbon group. The above-mentioned divalent aliphatic hydrocarbon group preferably has 1 to 10 carbon atoms, more preferably 1 to 8 carbon atoms, and even more preferably 5 to 7 carbon atoms. Examples of the above-mentioned divalent aliphatic hydrocarbon group include -C(CH ３ ) ２ -CH ２ -C(=CH ２ )-,-COO-CH ２ -, -CH ２ -, -CH ２ -O-CH ２ -, -CH ２ -COO-CH ２ --, --COO-CH ２ CH ２ - or a combination thereof is preferred, and -C(CH ３ ) ２ -CH ２ -C(=CH ２ ) - or -CH ２ - is more preferred, and -C(CH ３ ) ２ -CH ２ -C(=CH ２ )- is more preferred.

[0044] Examples of aromatic compounds having two or more aromatic rings include the following compounds.

[0045]

[0046] The aromatic compounds may be used alone or in combination of two or more. The content of the aromatic compounds is preferably 1.0 to 80.0% by mass, more preferably 3.0 to 60.0% by mass, and even more preferably 10.0 to 40.0% by mass, based on the total mass of the microscope immersion oil. The ratio of the mass of the specific compound to the mass of the aromatic compound (mass of specific compound / mass of aromatic compound) is preferably 0.01 to 20.0, and from the viewpoint of a better Abbe number, more preferably 0.5 to 5.8.

[0047] <Polyol> The microscope immersion oil contains a polyol. The polyol is an organic compound having two or more hydroxy groups. The polyol is a compound different from the various components described above. The polyol is preferably selected from the group consisting of polyester polyol, polyether polyol, and polycarbonate polyol, and polyester polyol is more preferable. The polyol is also preferably a liquid polyol. A liquid polyol is a polyol that is in a liquid state at room temperature (25°C).

[0048] The polyester polyol is preferably a condensate of a dihydric or higher alcohol with a divalent or higher carboxylic acid, more preferably a condensate of a dihydric alcohol with a divalent carboxylic acid. Examples of the dihydric or higher alcohol include 3-methyl-1,5-pentanediol, 1,9-nonanediol, ethylene glycol, propylene glycol, 1,4-butanediol, neopentyl glycol, 1,6-hexane glycol, 1,10-decanediol, and alkylene oxides of bisphenol A (e.g., ethylene oxide and propylene oxide), with 3-methyl-1,5-pentanediol being preferred. Examples of divalent or higher carboxylic acids include aliphatic dicarboxylic acids (e.g., succinic acid, adipic acid, azelaic acid, sebacic acid, dodecanedioic acid, fumaric acid, and maleic acid), alicyclic dicarboxylic acids (e.g., dimer acid), aromatic dicarboxylic acids (e.g., terephthalic acid, isophthalic acid, and phthalic acid), anhydrides thereof (e.g., succinic anhydride, maleic anhydride, and phthalic anhydride), acid halides thereof (e.g., adipic acid dichloride), low-molecular-weight alkyl esters thereof (e.g., dimethyl succinate and dimethyl phthalate), trimellitic acid, and pyromellitic acid, with aliphatic dicarboxylic acids being preferred, and adipic acid being more preferred.

[0049] Examples of polyester polyols include polyethylene adipate diol, polybutylene adipate diol, polyhexamethylene adipate diol, polyhexamethylene isophthalate diol, polyhexamethylene terephthalate diol, polyneopentyl adipate diol, polyethylene propylene adipate diol, polyethylene butylene adipate diol, polybutylene hexamethylene adipate diol, polydiethylene adipate diol, poly(polytetramethylene ether) adipate diol, poly(3-methylpentylene adipate) diol, polyethylene azelate diol, polyethylene sebacate diol, polybutylene azelate diol, polybutylene sebacate diol, and polyneopentyl terephthalate diol.

[0050] Commercially available polyester polyols include, for example, Sun-Estar 2610 (polyethylene adipate diol, manufactured by Sanyo Chemical Industries, Ltd.), Sun-Estar 4620 (polytetramethylene adipate diol, manufactured by Sanyo Chemical Industries, Ltd.), Sun-Estar 2620 (polyethylene adipate diol, manufactured by Sanyo Chemical Industries, Ltd.), Kuraray Polyol P-2010, Kuraray Polyol P-3010, Kuraray Polyol P-6010, Kuraray Polyol P-2020, and Kuraray Polyol P-2030 (all of which are poly-3-methyl-1,5-pentane isophthalate diol, manufactured by Kuraray Co., Ltd.).

[0051] Examples of polyether polyols include aliphatic polyether polyols and aromatic ring-containing polyether polyols. Examples of aliphatic polyether polyols include polyoxyethylene polyols (e.g., polyethylene glycol), polyoxypropylene polyols (e.g., polypropylene glycol), polyoxyethylene / propylene polyols, and polytetramethylene ether glycol. Examples of aromatic ring-containing polyether polyols include polyols having a bisphenol skeleton, such as an ethylene oxide adduct of bisphenol A and a propylene oxide adduct of bisphenol A, and alkylene oxide adducts of resorcinol.

[0052] Examples of polycarbonate polyols include aliphatic polycarbonate polyols, alicyclic polycarbonate polyols, and aromatic polycarbonate polyols. Examples of aliphatic polycarbonate polyols include polyhexamethylene carbonate diol, polydecamethylene carbonate diol, polypentamethylene carbonate diol, 3-methyl-5-pentane carbonate diol, polytetramethylene carbonate diol, and poly(tetramethylene / hexamethylene) carbonate diol. Examples of alicyclic polycarbonate polyols include polycyclohexamethylene carbonate diol and polynorbornene carbonate diol. Examples of aromatic polycarbonate polyols include poly 1,4-xylylene carbonate diol, bisphenol A polycarbonate diol, and bisphenol F polycarbonate diol.

[0053] The number average molecular weight of the polyol is preferably 500 to 10,000, more preferably 1,000 to 7,000. The number average molecular weight is a polystyrene-equivalent value measured by gel permeation chromatography (GPC). The viscosity of the polyol at 25°C is preferably 100 to 100,000 (unit: mPa s), more preferably 4,000 to 80,000 (unit: mPa s). The viscosity can be measured using a Cannon-Fenske viscometer.

[0054] The polyol content is preferably 1.0 to 80.0% by mass, more preferably 10.0 to 60.0% by mass, and even more preferably 15.0 to 30.0% by mass, based on the total mass of the immersion oil for microscopes.

[0055] The microscope immersion oil may contain known additives used in microscope immersion oils such as ordinary immersion oils for fluorescent microscopes, as long as the effects of the immersion oil as a whole are not impaired.

[0056] The refractive index of the microscope immersion oil at a wavelength of 546 nm is preferably 1.517 to 1.519. The refractive index can be measured using an Abbe refractometer. The Abbe number of the microscope immersion oil at a wavelength of 546 nm is preferably 39 to 47, more preferably 41 to 45. The Abbe number can be measured using an Abbe refractometer. The kinematic viscosity of the microscope immersion oil at 23°C is 50 to 1500 mm ２ / s is preferred, and 400 to 1200 mm ２ The kinematic viscosity can be measured using an automatic kinematic viscometer (for example, SVM3000 (manufactured by Anton Paar)).

[0057] The immersion oil for microscopes can be suitably used as an immersion oil for ordinary microscopes (particularly as an immersion oil for fluorescent microscopes).

[0058] <Method for producing microscope immersion oil> There are no particular limitations on the method for producing the microscope immersion oil, and any known method can be used. For example, the above-mentioned components can be mixed by stirring to produce the microscope immersion oil. When mixing, the components to be used may be mixed all at once, or the components may be mixed stepwise in various orders.

[0059] The microscope immersion oil of the present disclosure will be explained in more detail below with reference to examples and comparative examples, but the invention is not limited to these examples in any way.

[0060] <Method for Evaluating Microscope Immersion Oils> (Refractive Index Evaluation) Using a multi-wavelength Abbe refractometer DR-M2 (manufactured by Atago Co., Ltd.), the refractive index (wavelength 546 nm) of the microscope immersion oil to be measured was measured. The obtained values ​​were evaluated according to the following criteria. In practice, an evaluation of "A" is preferable. "A": Refractive index is 1.517 to 1.519 "B": Refractive index is less than 1.517 or more than 1.519

[0061] (Abbe number evaluation) Using a multi-wavelength Abbe refractometer DR-M2 (manufactured by Atago Co., Ltd.), the refractive index of the microscope immersion oil to be measured was measured at wavelengths of 480 nm, 546 nm, and 644 nm. Using the refractive indices at the three wavelengths, the Abbe number ν was calculated using the following formula (5): ｅ The Abbe number at a wavelength of 546 nm was calculated. ｅis a value indicating the refractive index wavelength dispersion.

[0062]

[0063] ν ｅ : Abbe number based on e-line (546 nm) n ｅ : refractive index for Fraunhofer e-line (546 nm) n Ｆ’ : refractive index for Fraunhofer F' line (480 nm) n Ｃ’ : Refractive index for Fraunhofer C' line (644 nm)

[0064] The Abbe number ν was calculated according to the following criteria: ｅ In practice, a rating of "B" or higher is preferable, and a rating of "A" is even more preferable.

[0065] "A": Abbe number is 41 to 45. "B": Abbe number is 39 or more and less than 41, or more than 45 and less than 47. "C": Abbe number is 35 or more and less than 39, or more than 47 and less than 51. "D": Abbe number is less than 35 or more than 51.

[0066] (Kinematic Viscosity Measurement) Using an automatic kinematic viscometer SVM3000 (manufactured by Anton Paar), the kinematic viscosity (temperature: 23°C) of the microscope immersion oil, which was the measurement object, was measured. The obtained values ​​were evaluated according to the following criteria. In practical use, an evaluation of "B" or higher is preferable, and an evaluation of "A" is even more preferable.

[0067] "A": kinematic viscosity is 400 to 1200 mm ２ / s "B": kinematic viscosity is 50 mm ２ / s or more 400mm ２ / s or less than 1200 mm ２ / s over 1500mm ２ / s or less "C": kinematic viscosity is 50 mm ２ / s or less than 1500 mm ２ / s super

[0068] (Evaluation of plastic erosion) A few drops of microscope immersion oil were dropped onto a plastic container for cell observation. After 72 hours at room temperature (23°C ± 2°C), the microscope immersion oil on the plastic container for cell observation was wiped off, and the appearance of the plastic container for cell observation was visually observed. As the plastic container for cell observation, a product name "Micro Dish 35 mm (μ-Dish 35 mm)" manufactured by Ibidi was used. In practical terms, a rating of "A" is preferable.

[0069] "A": The appearance of the plastic container for cell observation did not change. "B": The appearance of the plastic container for cell observation became cloudy or was eroded.

[0070] <Preparation of Immersion Oil for Microscopes> Immersion oil for microscopes was prepared by mixing the components shown in Table 1 below at 25° C. for 10 minutes so as to obtain the contents (% by mass) shown in Table 1. The evaluation results of the obtained immersion oil for microscopes are shown in Table 1.

[0071]

[0072] In Table 1 above, "PEMP-LV" is a specific compound (refractive index: 1.53, Abbe number: 46, liquid compound) manufactured by SC Organic Chemicals, Inc. "TMMP-LV" is a specific compound (refractive index: 1.52, Abbe number: 47, liquid compound) manufactured by SC Organic Chemicals, Inc.

[0073]

[0074] "2-Phenoxyethanol" is an aromatic compound manufactured by Tokyo Chemical Industry Co., Ltd. (refractive index: 1.54, Abbe number: 31, liquid aromatic compound). "(Phenylthio)methyl acetate" is an aromatic compound manufactured by Tokyo Chemical Industry Co., Ltd. (refractive index: 1.56, Abbe number: 30, liquid aromatic compound). "2,4-Diphenyl-4-methyl-1-pentene" is an aromatic compound manufactured by Tokyo Chemical Industry Co., Ltd. (refractive index: 1.57, Abbe number: 29, liquid aromatic compound). "P-5010" is polyester polyol P-5010 manufactured by Kuraray Co., Ltd. (refractive index: 1.48, Abbe number: 59, number average molecular weight: 5000, viscosity (25°C): 47000 mPa s, liquid polyol). "P-2010" is polyester polyol P-2010 (refractive index: 1.48, Abbe number: 59, number average molecular weight: 2000, viscosity (25°C): 5700 mPa·s, liquid polyol) manufactured by Kuraray Co., Ltd. "P-6010" is polyester polyol P-6010 (refractive index: 1.48, Abbe number: 58, number average molecular weight: 6000, viscosity (25°C): 68000 mPa·s, liquid polyol) manufactured by Kuraray Co., Ltd.

[0075] The numerical values ​​in the component column in Table 1 above represent the mass % of each component relative to the total mass of the microscope immersion oil. Also, "mass of specific compound / mass of aromatic compound" represents the ratio of the mass of the specific compound to the mass of the aromatic compound.

[0076] As shown in Table 1 above, it was confirmed that microscope immersion oils containing specified components suppress the corrosion of plastic materials and satisfy the refractive index, Abbe number, and kinematic viscosity characteristics required of microscope immersion oils. Furthermore, a comparison of Examples 2 to 4, 6, 8, and 9 confirmed that a superior Abbe number was achieved when the content of the compound represented by formula (1), where X is a carbon atom and n is 4, was 30.0 to 58.0 mass% relative to the total mass of the microscope immersion oil. Furthermore, a comparison of Examples 1, 5, 7, and 10 confirmed that a superior Abbe number was achieved when the content of the compound represented by formula (1), where X is a carbon atom and n is 3, was 30.0 to 70.0 mass% relative to the total mass of the microscope immersion oil. Furthermore, a comparison of Examples 1 to 10 confirmed that a superior Abbe number was achieved when the ratio of the mass of the compound represented by formula (1) to the mass of the aromatic compound was 0.5 to 5.8.

Claims

1. An immersion oil for microscopes comprising a compound represented by formula (1), an aromatic compound, and a polyol. １ -CO-O-R ２ ) ｐ -X-(R ３ ) ｑ In formula (1), R １ represents an alkyl group having a mercapto group. ２ represents a single bond or an alkylene group. ３ represents a hydrogen atom or an alkyl group, and X represents a carbon atom or a group represented by formula (A). In formula (A), * represents a bonding position. When X represents a carbon atom, p represents n, q represents 4-n, and n represents 3 or 4. When X represents a group represented by formula (A), p represents m, q represents 6-m, and m represents 5 or 6.

2. The microscope immersion oil of claim 1, wherein the aromatic compound is selected from the group consisting of aromatic compounds having a hydroxy group, aromatic compounds having a sulfur atom or a nitrogen atom, and aromatic compounds having two or more aromatic rings.

3. The microscope immersion oil according to claim 1 or 2, wherein the aromatic compound is selected from the group consisting of a compound represented by formula (2), a compound represented by formula (3), and a compound represented by formula (4). Formula (2) Ar １ - (L １ -OH) ｖ In formula (2), Ar １ represents an aromatic hydrocarbon ring. １ has at least one -CH ２ - represents an alkylene group which may be substituted with -O-, and v represents 1 or 2. Formula (3) Ar ２ - (L ２ -S-R ４ ) ｗ In formula (3), Ar ２ represents an aromatic hydrocarbon ring. ２ represents a single bond or an alkylene group. ４ has at least one -CH ２ represents a monovalent aliphatic hydrocarbon group which may be substituted with —COO—, and w represents 1 or 2. ３ -L ３ -Ar ４ In formula (4), Ar ３ and Ar ４ each independently represents an aromatic hydrocarbon ring which may have a substituent. ３ has at least one -CH ２ - represents a divalent aliphatic hydrocarbon group which may be substituted with -O- or -COO-, or -O-.

4. An immersion oil for microscopes according to any one of claims 1 to 3, wherein the polyol is selected from the group consisting of polyester polyols, polyether polyols, and polycarbonate polyols.

5. An immersion oil for microscopes according to any one of claims 1 to 4, wherein X is a carbon atom, n is 4, and the content of the compound represented by formula (1) is 30.0 to 58.0 mass % relative to the total mass of the immersion oil for microscopes.

6. An immersion oil for microscopes according to any one of claims 1 to 4, wherein X is a carbon atom, n is 3, and the content of the compound represented by formula (1) is 30.0 to 70.0 mass % relative to the total mass of the immersion oil for microscopes.

7. An immersion oil for microscopes according to any one of claims 1 to 4, wherein the ratio of the mass of the compound represented by formula (1) to the mass of the aromatic compound is 0.5 to 5.8.

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