Coolant containing organopolysiloxane

Abstract

To provide a coolant which exhibits relatively excellent fluidity even at low temperatures and can be easily handled and stored due to having a high flash point.SOLUTION: This coolant contains an organopolysiloxane represented by formula (1) (wherein R1 moieties are each independently a methyl group or an ethyl group, and n is 2 or 3), and is characterized in that the organopolysiloxane has a kinematic viscosity of 100 mm2 / s or less at -80°C and 300 mm2 / s or less at -100°C.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to an organopolysiloxane suitable as a refrigerant for a cooling device having a mechanism for forced refrigerant circulation. That is, the present invention relates to a refrigerant containing an organopolysiloxane, and more specifically to a refrigerant for use in a cooling device having a mechanism for forced refrigerant circulation. [Background technology]

[0002] Cooling systems that use forced circulation pumps or other devices to circulate refrigerants are used in a wide range of applications, including cooling electronic devices, heat exchange in manufacturing plants, and air conditioning. Operating temperatures range from as low as -30°C to as high as 150°C, but special applications may require cooling to cryogenic temperatures of -30°C to -100°C. Known refrigerant oils include mineral oil, alcohols, and halogenated hydrocarbons. However, mineral oils have high viscosity at low temperatures, placing a heavy load on the circulation pump. Alcohols are toxic and flammable, and halogenated hydrocarbons contribute to global warming, leading to their use being restricted. For these reasons, fluorinated refrigerants, which have low viscosity and low flammability even at cryogenic temperatures, have been widely used as refrigerant oils. However, the persistence of fluorinated compounds has become a concern in recent years, and restrictions on their use are being considered.

[0003] Given these circumstances, there is a demand for alternative refrigerants to fluorocarbons, and silicone oils, which maintain fluidity even at low temperatures, have attracted attention. The use of silicone oils as refrigerants has been investigated in the past (Patent Document 1). However, the specification stipulated that a flash point of 60°C or higher would be sufficient, but this standard is insufficient in light of Japan's Fire Service Act and other regulations. Mixtures of decamethyltetrasiloxane and hexamethyldisiloxane have also been proposed, but these have low fluidity at low temperatures but high volatility and flash points below 100°C (Patent Document 2). Refrigerants primarily composed of siloxane oligomers have also been proposed, but they also have excellent fluidity at low temperatures but a low flash point (Patent Document 3). The development of alternatives to fluorocarbons for refrigeration applications is an urgent issue, and there has been a need for refrigerants that maintain fluidity at low temperatures and have a high flash point. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 07-166061 [Patent Document 2] Japanese Patent Application Publication No. 02-242878 [Patent Document 3] Japanese Patent Application Laid-Open No. 2001-262168 Summary of the Invention [Problem to be solved by the invention]

[0005] An object of the present invention is to provide a refrigerant that has relatively good fluidity even at low temperatures, a high flash point, and is easy to handle and store. [Means for solving the problem]

[0006] The present inventors have discovered that organopolysiloxanes having a specific structure exhibit fluidity at cryogenic temperatures while also having a high flash point, making them suitable as refrigerant oils for cooling devices.

[0007] That is, the present invention is [1] A refrigerant containing an organopolysiloxane represented by the following formula (1): [ka] (where R 1 are, independently of one another, a methyl group or an ethyl group, and n is 2 or 3. The organopolysiloxane has a kinematic viscosity of 100 mm at -80°C. 2 / s or less, and a kinematic viscosity of 300mm at -100°C 2 / s or less.

[0008] Furthermore, the present invention provides the above refrigerant, which further has at least one component selected from the following: [2] R in the above formula (1) 1 is a methyl group. [3] R in the above formula (1) 1 is a methyl group and n is 3. [4] R in the above formula (1) 1 is an ethyl group. [5] R in the above formula (1) 1 is an ethyl group and n is 2. [6] The above refrigerant, which is a refrigerant for a cooling device. [7] The above refrigerant, wherein the cooling device has a mechanism for forced circulation of the refrigerant. More preferably, the present invention provides a refrigerant comprising an organopolysiloxane represented by the above formula (1). [Effects of the Invention]

[0009] The organopolysiloxane compound of the present invention has a high flash point while maintaining good fluidity at cryogenic temperatures, and therefore can be used as a refrigerant oil over a wide temperature range. DETAILED DESCRIPTION OF THE INVENTION

[0010] The present invention is a refrigerant containing an organopolysiloxane represented by the following formula (1): [ka] (where R 1 are independently selected from a methyl group or an ethyl group, and n is 2 or 3. The organopolysiloxane has a kinematic viscosity of 100mm at -80°C. 2 / s or less, and a kinematic viscosity of 300mm at -100°C 2 Preferably, the organopolysiloxane has a kinematic viscosity of 15 to 100 mm / s at −80° C. 2 / s, and the kinematic viscosity at -100°C is 100 to 300 mm 2 / s and is characterized by its safe use over a wide temperature range, including cryogenic temperatures.

[0011] Examples of organopolysiloxanes represented by the above formula (1) include decamethyltetrasiloxane, dodecamethylpentasiloxane, 3-ethyl-1,1,1,3,5,5,7,7,7-nonamethyltetrasiloxane, 3,5-diethyl-1,1,1,3,5,7,7,7-octamethyltetrasiloxane, 3-ethyl-1,1,1,3,5,5,7,7,9,9,9-undecamethylpentasiloxane, 5 3,5-diethyl-1,1,1,3,3,5,7,7,9,9,9-undecamethylpentasiloxane, 3,5-diethyl-1,1,1,3,5,7,7,9,9,9-decamethylpentasiloxane, 3,7-diethyl-1,1,1,3,5,5,7,9,9,9-decamethylpentasiloxane, 3,5,7-triethyl-1,1,1,3,5,7,9,9,9-nonamethylpentasiloxane, etc. Among these, dodecamethylpentasiloxane and 3,5-diethyl-1,1,1,3,5,7,7,7-octamethyltetrasiloxane are preferred.

[0012] More preferably, R in the above formula (1) 1 When R is a methyl group, n is preferably 3. 1 When is an ethyl group, n is preferably 2.

[0013] The organopolysiloxane of the present invention has a kinematic viscosity of 100 mm at -80°C. 2 / s or less, preferably a kinematic viscosity of 15 to 100 mm 2 / s, and a kinematic viscosity of 300mm at -100°C. 2 / s or less, preferably a kinematic viscosity of 100 to 300 mm 2 More preferably, the kinematic viscosity at -80°C is 20 to 80 mm 2 / s, and a kinematic viscosity of 150 to 280 mm at -100°C. 2 / s. In the present invention, the kinematic viscosity at 0°C or below, for example, -80°C or -100°C, is a value measured using a rheometer in an environmental test chamber cooled with liquid nitrogen under the following conditions. [Measurement conditions] Equipment: DHR-2, environmental test chamber (manufactured by TA Instruments) Shear rate::1,000s -1 Plate: Aluminum parallel plate (upper diameter 25 mm, lower diameter 40 mm, gap 0.5 mm) The absolute viscosity obtained as a measurement result was converted to kinematic viscosity using the following formula (a) from the absolute viscosity and specific gravity at the measurement temperature T°C. The specific gravity (T°C) at the measurement temperature T°C was calculated using the following formula (b). Kinematic viscosity (T℃) = Absolute viscosity (T℃) / Specific gravity (T℃) Formula (a) Specific gravity (T℃)=0.0009×(25-T)+specific gravity (25℃) Formula (b)

[0014] The organopolysiloxane of the present invention can be produced by commonly known methods, such as cohydrolysis of trimethylchlorosilane and dimethyldichlorosilane, or equilibration reaction of hexamethyldisiloxane with a cyclic polysiloxane compound, typically octamethylcyclotetrasiloxane or decamethylcyclopentasiloxane, using an acid. Catalysts for the equilibration reaction include acidic catalysts such as sulfuric acid, fuming sulfuric acid, p-toluenesulfonic acid, trifluoromethanesulfonic acid, and hydrochloric acid. The amount of catalyst added is typically 0.01% to 5% of the organopolysiloxane raw material, and the reaction is typically carried out at a temperature of 0°C to 100°C.

[0015] The organopolysiloxane obtained by cohydrolysis or equilibration reaction can be purified by a rectification step after removing by-product acids and catalytic acids with water washing or a neutralizing agent, or by subjecting organohydrogensiloxane to an addition reaction with ethylene.

[0016] The organopolysiloxane of the present invention preferably has a flash point of 50° C. or higher, more preferably 80 to 160° C. The flash point in the present invention is measured by the Cleveland open method described in JIS K2265-4:2007.

[0017] The refrigerant of the present invention can be suitably used as a refrigerant for a cooling device having a mechanism for forced circulation of the refrigerant, such as a refrigerant storage tank, a refrigerant circulation device, a refrigerator for cooling the refrigerant, or a forced circulation type cooling device using a heat exchanger. [Example]

[0018] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to the following examples.

[0019] [Example 1] Represented by the above formula (1), R 1are all methyl groups and n is 3, organopolysiloxane (KF-96L-2cs, manufactured by Shin-Etsu Chemical Co., Ltd.)

[0020] [Example 2] Represented by the above formula (1), R 1 are all ethyl groups and n is 2, organopolysiloxane (KF-4422, manufactured by Shin-Etsu Chemical Co., Ltd.)

[0021] [Comparative Example 1] Represented by the above formula (1), R 1 are all methyl groups and n is 1. Organopolysiloxane (KF-96L-1cs, manufactured by Shin-Etsu Chemical Co., Ltd.)

[0022] The kinematic viscosity and flash point were measured for the organopolysiloxanes of Examples 1 and 2 and Comparative Example 1. The results are shown in Table 1 below. The kinematic viscosity at 25°C was measured using a Cannon-Fenske viscometer according to the method described in JIS Z8803:2011. The kinematic viscosities at 0°C, -20°C, -40°C, -60°C, -80°C and -100°C were measured using a rotational rheometer according to the measurement conditions described above. The flash point was measured by a Cleveland open-type method in accordance with JIS K2265-4:2007.

[0023] [Table 1]

[0024] As described above, the organopolysiloxane of the present invention has a high flash point while maintaining fluidity at cryogenic temperatures, and therefore can be used as a refrigerant oil in cooling devices having a mechanism for forced circulation of the refrigerant.

Claims

1. A refrigerant containing an organopolysiloxane represented by the following formula (1): 【Chemistry 1】 (Here, R １ are, independently of one another, a methyl group or an ethyl group, and n is 2 or 3. The organopolysiloxane has a kinematic viscosity of 100 mm at −80° C. ２ / s or less, and a kinematic viscosity of 300 mm at -100°C ２ / s or less.

2. R in the above formula (1) １ 2. The refrigerant of claim 1, wherein all of are methyl groups.

3. R in the above formula (1) １ 3. The refrigerant of claim 2, wherein all of are methyl groups and n is 3.

4. R in the above formula (1) １ 2. The refrigerant of claim 1, wherein all of are ethyl groups.

5. R in the above formula (1) １ 5. The refrigerant of claim 4, wherein all of are ethyl groups and n is 2.

6. The refrigerant according to any one of claims 1 to 5, which is a refrigerant for a cooling device.

7. The refrigerant according to claim 6, wherein the cooling device has a mechanism for forced circulation of the refrigerant.

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