Refrigerant composition, refrigerant for cooling device, and cooling device

Abstract

[Problem] The purpose of the present invention is to provide a refrigerant composition which exhibits relatively excellent fluidity even at low temperatures and can be easily handled and stored due to having a high flash point. [Solution] Provided is a refrigerant composition that contains a linear organopolysiloxane represented by formula (1) (in the formula, n is an integer of 1-20), wherein: (A) a linear organopolysiloxane represented by formula (1) in which n is 4 or 5 is contained, and the amount of the linear organopolysiloxane is 90-100 mass% with respect to the total mass of components (A)-(C); (B) the amount of a linear organopolysiloxane represented by formula (1) in which n is 3 or less is 10 mass% or less with respect to the total mass of components (A)-(C); and (C) the amount of a linear organopolysiloxane represented by formula (1) in which n is 6 or more is 10 mass% or less with respect to the total mass of components (A)-(C).

Description

Refrigerant Composition, Refrigerant for Cooling Device, and Cooling Device

[0001] The present invention relates to a refrigerant composition containing organopolysiloxane and a cooling device using the same. In particular, it relates to an organopolysiloxane composition suitable for use as a refrigerant in a cooling device having a mechanism for forced circulation of the refrigerant.

[0002] Cooling devices that perform forced circulation of the refrigerant by a circulation pump or the like are used in a wide range of applications such as cooling of electronic devices, heat exchange in manufacturing plants, and air conditioning. The operating temperature ranges widely from a low temperature of about -30°C to a high temperature region of about 150°C, but for special applications, cooling down to an extremely low temperature of about -30°C to -100°C is required. As refrigerant oils, mineral oils, alcohols, halogenated hydrocarbons, etc. are known. However, mineral oils have a high viscosity in the low temperature region, resulting in a large load on the circulation pump. Also, alcohols have a relatively low flash point, and care is required for handling and storage. Furthermore, halogenated hydrocarbons are considered to contribute to global warming, and their use is regulated.

[0003] Therefore, fluorocarbons, which are a type of halogenated hydrocarbon with low viscosity and low flammability even in the extremely low temperature region, have been widely used as refrigerant oils. However, in recent years, the non-decomposability of fluorine-based compounds such as fluorocarbons has been regarded as a problem, and restrictions on their use have been under consideration.

[0004] Therefore, there is a demand for alternative refrigerants to fluorocarbons, and silicone oil, which maintains fluidity even at low temperatures, is attracting attention. As described in Patent Document 1, studies on using silicone oil as a refrigerant have been conducted before. In the specification of Patent Document 1, the standard was that the flash point should be 60°C or higher, but considering Japan's Fire Service Act and other regulations, this standard is insufficient. Patent Document 2 describes a mixture of decamethyltetrasiloxane and hexamethyldisiloxane, but these have low fluidity at low temperatures, high volatility, and a flash point of less than 100°C. Patent Document 3 describes a refrigerant mainly composed of siloxane oligomers, which also have excellent fluidity at low temperatures but a low flash point. The development of fluorocarbon alternatives for refrigerant applications is an urgent issue, and there is a need for a refrigerant that maintains fluidity at low temperatures and has a high flash point.

[0005] JP 07-166061 JP 02-242878 JP 2001-262168

[0006] The present invention aims to provide a refrigerant composition that exhibits relatively good fluidity even at low temperatures, has a high flash point, and is easy to handle and store.

[0007] To solve the above problems, the present invention has found that an organopolysiloxane composition having the specific configuration shown below exhibits fluidity at extremely low temperatures while having a high flash point, making it suitable as a refrigerant oil for cooling devices.

[0008] In other words, the present invention relates to a refrigerant composition comprising [1] a linear organopolysiloxane represented by the following formula (1), (wherein n is an integer from 1 to 20) (A) A linear organopolysiloxane represented by formula (1) in which n is 4 or 5, wherein the amount of the linear organopolysiloxane is 90% by mass or more and 100% by mass or less relative to the total mass of components (A) to (C), (B) A linear organopolysiloxane represented by formula (1) in which n is 3 or less is 10% by mass or less relative to the total mass of components (A) to (C), and (C) A linear organopolysiloxane represented by formula (1) in which n is 6 or more is 10% by mass or less relative to the total mass of components (A) to (C).

[0009] Furthermore, the present invention provides the above-mentioned refrigerant composition having at least one configuration selected from the following, and a refrigerant containing the refrigerant composition. [2] The refrigerant composition is of the following formula (2) [1] A refrigerant composition according to [1] above, comprising less than 10 parts by mass of a cyclic polysiloxane represented by (wherein m is an integer from 3 to 7) in a quantity of 100 parts by mass of the total of components (A) to (C). [3] A refrigerant composition according to [1] or [2] above, wherein the refrigerant composition has a flash point of 130°C or higher as measured by the method described in ASTM D3828-16a (2021). [4] A refrigerant composition according to any one of [1] to [3] above, having a viscosity of 80 mPa·s or less at -60°C as measured by a rotary rheometer. [5] A refrigerant for a cooling device comprising the refrigerant composition according to any one of [1] to [4] above. [6] A cooling device using the refrigerant for a cooling device according to [5] above. [7] A cooling device according to [6] above, wherein the cooling device has a mechanism for forced circulation of the refrigerant.

[0010] The refrigerant composition of the present invention maintains good fluidity at low temperatures while having a high flash point, making it usable as a refrigerant over a wide temperature range.

[0011] The present invention relates to a refrigerant composition, which mainly comprises a linear organopolysiloxane represented by the following formula (1). (where n is an integer from 1 to 20, preferably an integer from 2 to 10) The refrigerant composition of the present invention comprises (A) a linear organopolysiloxane represented by formula (1) above, where n is 4 or 5, wherein the amount of the linear organopolysiloxane is 90% by mass or more and 100% by mass or less relative to the total mass of components (A) to (C), (B) a linear organopolysiloxane represented by formula (1) above, where n is 3 or less, where the amount is 10% by mass or less relative to the total mass of components (A) to (C), and (C) a linear organopolysiloxane represented by formula (1) above, where n is 6 or more, where the amount is 10% by mass or less relative to the total mass of components (A) to (C).

[0012] Component (A) is a linear organopolysiloxane represented by the above formula (1) where n is 4 or 5. The refrigerant composition of the present invention is characterized in that it contains component (A) in an amount of 90% by mass or more and 100% by mass or less, preferably 94% by mass or more and 100% by mass or less, relative to the total mass of components (A) to (C). The upper limit of component (A) may be less than 100% by mass, or 90% by mass or more and 100% by mass or less, and preferably 94% by mass or more and 100% by mass or less. The content of component (A) in the refrigerant composition of the present invention is 90% by mass or more and 100% by mass or less, preferably 94% by mass or more and 100% by mass or less, relative to the total mass of the refrigerant composition.

[0013] Component (B) is a linear organopolysiloxane represented by the above formula (1) where n is 3 or less. The refrigerant composition of the present invention is characterized in that the total amount of the linear organopolysiloxane is 10% by mass or less, preferably 5% by mass or less, relative to the total mass of components (A) to (C). If the amount is greater than the above upper limit, the fluidity of the refrigerant composition at low temperatures will improve, but the flash point will be lower, which is undesirable for handling. The lower limit of the amount of component (B) is not particularly limited and should be the detection limit. Therefore, it is preferably 0% by mass, but it may be greater than 0% by mass. Preferably, the content of component (B) may be greater than 0% by mass and less than 10% by mass, relative to the total mass of components (A) to (C), and preferably greater than 0% by mass and 5% by mass or less.

[0014] Component (C) is a linear organopolysiloxane represented by the above formula (1) where n is 6 or more. The total amount of the linear organopolysiloxane is 10% by mass or less, preferably 5% by mass or less, relative to the total mass of components (A) to (C). If the amount is greater than the above upper limit, the flash point of the refrigerant composition will be higher, but the viscosity in the low-temperature range will be higher, which is undesirable. The lower limit of the amount of component (C) is not particularly limited and should be the detection limit. Therefore, it is preferably 0% by mass, but it may be greater than 0% by mass. Preferably, the content of component (C) may be greater than 0% by mass and less than 10% by mass, relative to the total mass of components (A) to (C), and may be greater than 0% by mass and 5% by mass or less.

[0015] The refrigerant composition of the present invention preferably contains less than 10 parts by mass of cyclic polysiloxane represented by the following formula (2) per 100 parts by mass of the total of components (A) to (C). If the amount is 10 parts by mass or more, these cyclic polysiloxanes are undesirable because they lower the flash point of the refrigerant composition. The lower limit of the cyclic polysiloxane content is not particularly limited and should be the detection limit. Therefore, it is preferably 0 parts by mass, but it may be greater than 0 parts by mass. Preferably, the cyclic polysiloxane content should be greater than 0 parts by mass and less than 10 parts by mass per 100 parts by mass of the total of components (A) to (C), and may be greater than 0 parts by mass and 8 parts by mass or less. (Here, m is an integer between 3 and 7.)

[0016] In this invention, the values ​​of n and m were measured by gas chromatography under the following conditions: [Measurement conditions] Apparatus: Shimadzu Nexis GC-2030 gas chromatograph Carrier gas: Helium Flow rate: 0.6 mL / min Detector: Flame ionization detector (FID) Detector temperature: 320°C Column: DB-5MS (inner diameter 0.53 mmφ × length 30 m, packing material: silica) (Agilent Technologies) Column temperature: 50 → 280°C (heating rate: 10°C / min) Sample injection volume: 1.0 μL Internal standard: n-tetradecane

[0017] The organopolysiloxanes in the present invention can be produced by generally known methods, such as co-hydrolysis of trimethylchlorosilane and ethylmethyldichlorosilane, or by equilibration reaction with an acid or base catalyst of hexamethyldisiloxane or a cyclic polysiloxane compound represented by 3,5-diethyl-1,1,1,3,5,7,7,7-octamethyltetrasiloxane and 1,3,5,7-tetraethyl-1,3,5,7-tetramethylcyclotetrasiloxane.

[0018] Examples of catalysts for equilibration reactions include acidic catalysts such as sulfuric acid, fuming sulfuric acid, p-toluenesulfonic acid, trifluoromethanesulfonic acid, and hydrochloric acid, as well as basic catalysts such as metal hydroxides like sodium hydroxide and potassium hydroxide, and reaction products of dimethylsiloxane and alkali metals. The amount of catalyst added is typically 0.5% to 5% relative to the siloxane raw material, and the reaction temperature is generally 0°C to 100°C for acidic catalysts and 100°C to 180°C for basic catalysts.

[0019] From the polysiloxane obtained by co-hydrolysis or equilibration reaction, by-product acids and catalyst acids or bases are removed by washing with water or by using a neutralizing agent or adsorbent, and then the organopolysiloxane of the present invention is obtained by a distillation process. The distillation process is preferably carried out under high reduced pressure at a temperature of 120°C to 220°C.

[0020] The refrigerant composition containing the linear organopolysiloxane of the present invention preferably has a viscosity of 80 mPa·s or less at -60°C, and more preferably 50 to 75 mPa·s, because if the viscosity at -60°C exceeds 80 mPa·s, the load on the circulation pump increases. In this invention, viscosity is measured using a rotary rheometer in an environmental test chamber cooled with liquid nitrogen under the following conditions. In this invention, viscosity refers to dynamic viscosity.

[0021] [Measurement Conditions] Equipment: DHR-2, Environmental Test Chamber (TA Instruments) Shear Rate: 1000 s －１ Plate: Aluminum parallel plate (upper diameter 25 mm, lower diameter 40 mm, gap 0.5 mm)

[0022] Furthermore, since it is desirable that the flash point of the refrigerant composition be higher than the operating temperature, it is preferably 130°C or higher, and more preferably 140°C to 200°C. In this invention, the flash point is the value measured using a Seta closed-type flash point measuring device by the method described in ASTM D3828-16a (2021).

[0023] The refrigerant composition of the present invention preferably comprises the components (A) to (C) described above, and an optional component (D). The refrigerant composition of the present invention may also contain other additives in amounts that do not impair the effects of the present invention.

[0024] The refrigerant composition of the present invention can be suitably used as a refrigerant for cooling systems. In particular, it is especially preferred as a refrigerant in a cooling system having a generally known mechanism for forced circulation of a refrigerant, such as a refrigerant storage tank, a refrigerant circulation device, a refrigerator for cooling the refrigerant, or a heat exchanger.

[0025] The present invention will be described in more detail below with reference to examples and comparative examples, but the present invention is not limited to the following examples.

[0026] [Example 1] 3,5-diethyl-1,1,1,3,5,7,7,7-octamethyltetrasiloxane (KF-4422, manufactured by Shin-Etsu Chemical Co., Ltd.) (169 g) and 1,3,5,7-tetraethyl-1,3,5,7-tetramethylcyclotetrasiloxane (88 g) were charged into a reaction vessel. Under a nitrogen atmosphere, trifluoromethanesulfonic acid (1.3 g) was added as an acidic catalyst, and the mixture was stirred at 50-60°C for 4 hours. Kyoward 500SH (10 g) was added, and the mixture was stirred at 25-30°C for 3 hours, followed by filtration. Distillation was carried out under reduced pressure at 120°C-220°C while confirming the composition by gas chromatography, yielding a colorless and transparent organopolysiloxane (14 g). The content of each organopolysiloxane component (A) to (C) and the cyclic polysiloxane in the obtained product is shown in Table 1. In Table 1 below, (A) is a linear organopolysiloxane represented by formula (1) above with n = 4 or 5, (B) is a linear organopolysiloxane represented by formula (1) above with n = 1 to 3, and (C) is a linear organopolysiloxane represented by formula (1) above with n = 6 to 10. Cyclic polysiloxanes are compounds represented by formula (2) above with m = 3 to 7.

[0027] [Comparative Example 1] Except for changing the proportion of the fraction collected during distillation, a colorless and transparent organopolysiloxane (20 g) was obtained in the same manner as in Example 1.

[0028] [Comparative Example 2] In the distillation process, a colorless and transparent organopolysiloxane (27 g) was obtained in the same manner as in Example 1, except that the proportion of the fraction collected was changed.

[0029] [Comparative Example 3] In the distillation process, a colorless and transparent organopolysiloxane (23 g) was obtained in the same manner as in Example 1, except that the proportion of the fraction to be collected was changed.

[0030] Table 1 shows the characteristic values ​​of the organopolysiloxanes obtained in Example 1 and Comparative Examples 1 to 3 described above.

[0031] The viscosity at 25°C, 0°C, -20°C, -40°C, -60°C, and -80°C was measured using a rotary rheometer according to the measurement conditions described above. The flash point was measured using a Ceta closed-type flash point analyzer according to the method described in ASTM D3828-16a (2021).

[0032]

[0033] As described above, the refrigerant composition of the present invention exhibits low viscosity even at low temperatures and has a sufficiently high flash point. Therefore, the refrigerant composition is useful as a refrigerant oil in a cooling system having a mechanism for forced circulation of refrigerant.

Claims

1. A refrigerant composition comprising a linear organopolysiloxane represented by the following formula (1), (wherein n is an integer from 1 to 20) (A) A refrigerant composition comprising a linear organopolysiloxane represented by formula (1) where n is 4 or 5, wherein the amount of the linear organopolysiloxane is 90% by mass or more and 100% by mass or less relative to the total mass of components (A) to (C), (B) A linear organopolysiloxane represented by formula (1) where n is 3 or less is 10% by mass or less relative to the total mass of components (A) to (C), and (C) A linear organopolysiloxane represented by formula (1) where n is 6 or more is 10% by mass or less relative to the total mass of components (A) to (C).

2. The refrigerant composition is the following formula (2) The refrigerant composition according to claim 1, comprising a cyclic polysiloxane represented by (wherein m is an integer from 3 to 7) in an amount of less than 10 parts by mass per 100 parts by mass of the total of components (A) to (C).

3. The refrigerant composition according to claim 1, having a flash point of 130°C or higher as measured by the method described in ASTM D3828-16a (2021).

4. The refrigerant composition according to claim 3, having a viscosity of 80 mPa·s or less at -60°C as measured by a rotary rheometer.

5. A refrigerant for a cooling device comprising the refrigerant composition described in claim 1.

6. A cooling device using the refrigerant for the cooling device described in claim 5.

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

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