Cold and heat storage composition

Abstract

To provide a cold and heat storage agent composition that does not fall into the GHS categories.SOLUTION: A cold and heat storage agent composition comprises: (A) a dialkyl ether; and (B) a normal paraffin, wherein the (A) contains a dialkyl ether having a straight chain alkyl group, the (B) contains a normal paraffin having 16 to 20 carbon atoms, and a content of the normal paraffin having 16 to 20 carbon atoms is 3.0 mass% or more and less than 10.0 mass% based on a total mass of the composition, and a melting point and a freezing point of the composition measured by DSC are within a range of -13.0°C to +12.4°C.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a cold storage composition for use in a refrigeration cycle device. [Background technology]

[0002] Vehicles equipped with an idling stop function that automatically stops the engine when the vehicle is stopped at a traffic light, etc., are now in practical use. These vehicles are equipped with a cold storage type vehicle air conditioning system that stores cold in a cold storage unit when the compressor is operating, and then cools the air blown into the passenger compartment from the cooler when the compressor is stopped. A cold storage agent or a cold storage agent composition is used in the above-mentioned vehicle air conditioner. Because water-based cold storage agents or compositions have problems of corrosion and decay, cold storage agents or compositions using normal paraffin as a base instead of water-based ones have been developed (for example, Patent Document 1). Normal paraffin has the advantage of exhibiting stable melting and solidification properties for a long period of time and having a large latent heat capacity. However, normal paraffin is classified as Category 1, the most hazardous of the five levels of aspiration hazard under the Globally Harmonized System of Classification and Labeling of Chemicals (GHS). Among normal paraffins, normal dodecane (n-C12) has a flash point below 93°C, so it is classified as a flammable liquid under the GHS classification. To be classified as an exemption from the GHS classification, the normal paraffin content in the cold / heat storage agent or cold / heat storage agent composition must be kept below 10% by mass. Furthermore, normal tetradecane (n-C14) is classified as a volatile organic compound (VOC), a substance subject to voluntary control by the Japan Automobile Manufacturers Association, so there is a tendency to avoid using n-C14. The use of dialkyl ether as a base for a heat storage material is disclosed, for example, in Patent Documents 2 and 3. Patent Document 2 discloses a combination of at least one selected from the group consisting of fatty acid esters, aliphatic ketones, fatty acid alcohols, and aliphatic ethers with a fatty acid metal salt. Patent Document 3 discloses microcapsules encapsulating a compound containing a hetero element as a heat storage material. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2013-166845 [Patent Document 2] Japanese Patent Application Laid-Open No. 2015-54918 [Patent Document 3] International Publication No. 2007 / 058003 Summary of the Invention [Problem to be solved by the invention]

[0004] The present invention aims to provide a cold / heat storage composition that is not subject to GHS classification. Another object of the present invention is to provide an aluminum refrigeration cycle device in which the cold storage composition of the present invention is enclosed. [Means for solving the problem]

[0005] As a result of intensive research by the present inventors to achieve the above object, they have found a cold storage composition that is not subject to the GHS classification by combining a specific dialkyl ether and a specific normal paraffin. That is, the present invention provides the following cold storage composition and an aluminum refrigeration cycle device in which the cold storage composition is enclosed. 1. A cold and heat storage composition comprising (A) a dialkyl ether and (B) a normal paraffin, (A) comprises a dialkyl ether having a linear alkyl group; (B) contains normal paraffins having 16 to 20 carbon atoms, and the content of the normal paraffins having 16 to 20 carbon atoms is 3.0 mass% or more and less than 10.0 mass% based on the total mass of the composition; The above cold / heat storage composition, wherein the melting point and freezing point of the composition measured by DSC are in the range of -13.0°C to +12.4°C. 2. The cold / heat storage composition according to claim 1, having a latent heat of fusion per volume of 125 KJ / L or more. 3. The cold / heat storage composition according to item 1 or 2 above, which has a flash point of 93°C or higher. 4. The cold / heat storage composition according to any one of the above items 1 to 3, wherein (A) contains a dialkyl ether having two linear alkyl groups having 6 to 12 carbon atoms. 5. The cold / heat storage composition according to any one of the above items 1 to 4, wherein (A) is a dialkyl ether having two linear alkyl groups having 8 to 10 carbon atoms. 6. The cold / heat storage composition according to any one of the above items 1 to 5, further comprising (C) a hydrogen generation inhibitor. 7. The cold / heat storage composition according to item 6, wherein (C) is at least one selected from the group consisting of amine salts, sulfonate salts, phosphate esters, and mixtures thereof. 8. The cold / heat storage composition according to any one of the above items 1 to 7, further comprising (D) an antioxidant. 9. The cold / heat storage composition according to any one of items 1 to 8, further comprising (E) at least one thickener selected from the group consisting of urea compounds, urethane compounds, carbon black, bentonite, and fumed silica. 10. An aluminum refrigeration cycle device in which the cold and heat storage agent composition according to any one of items 1 to 9 is enclosed. [Effects of the Invention]

[0006] According to the present invention, it is possible to provide a cold / heat storage agent composition that is not subject to GHS classification. DETAILED DESCRIPTION OF THE INVENTION

[0007] [Base] The above components (A) and (B) are the base of the cold / heat storage composition of the present invention. Component (A) contains a dialkyl ether having a linear alkyl group. It preferably contains a dialkyl ether having two linear alkyl groups each having 6 to 12 carbon atoms. It is more preferably at least one selected from the group consisting of dialkyl ethers having two linear alkyl groups each having 8 to 10 carbon atoms. The dialkyl ether may be used alone or in appropriate combination of two or more. The proportion of (A) dialkyl ether is preferably 60 mass% or more, more preferably 70 mass% or more, and particularly preferably 80 mass% or more, based on the total mass of the composition. When it is contained in such an amount, sufficient solid-liquid latent heat can be obtained, which is preferable.

[0008] Component (B) contains normal paraffins having 16 to 20 carbon atoms, and the content of normal paraffins having 16 to 20 carbon atoms is 3.0% by mass or more and less than 10.0% by mass, based on the total mass of the composition. A content of 10% by mass or more corresponds to Category 1 of the GHS classification, raising concerns about safety for the human body. A content of less than 3.0% by mass results in a melting point of +12.4°C or higher, making it impossible to sufficiently cool the air blown into the vehicle cabin from the cooler, making it unsuitable as a cold / heat storage agent. A content of 5.0 to 9.5% by mass is preferred. Component (B) preferably consists solely of normal paraffins having 16 to 20 carbon atoms, and more preferably consists solely of normal paraffins having 16 to 18 carbon atoms. Component (B) may be used alone or in appropriate combination of two or more types.

[0009] It is most preferred that (A) is at least one selected from the group consisting of dialkyl ethers having two linear alkyl groups each having 8 or 10 carbon atoms, and (B) is solely normal paraffins having 16 or 17 carbon atoms, or that (A) is a dialkyl ether having two linear alkyl groups each having 8 carbon atoms and (B) is solely normal paraffins having 16 or 17 carbon atoms, or that (A) is a dialkyl ether having two linear alkyl groups each having 10 carbon atoms and (B) is solely normal paraffins having 16 or 17 carbon atoms.

[0010] The melting point and freezing point of the composition of the present invention measured by DSC are in the range of -13.0°C to +12.4°C. The cold storage composition of the present invention can be used within this range. Two temperature ranges, -13.0°C to -3.0°C and +3.0°C to +12.4°C, are preferred. These two temperature ranges are assumed temperature ranges of two different refrigeration cycle devices, and if the temperature ranges are outside the ranges, sufficient cold storage performance may not be obtained.

[0011] Since cold storage agents are placed in containers and managed by volume, their performance is evaluated by the latent heat per volume (KJ / L), which is calculated by multiplying the latent heat per weight (J / g) by the density. The latent heat of fusion of normal paraffin with 15 carbon atoms, which is currently used as a cold storage agent, is 125 KJ / L, but the latent heat of fusion per volume of the composition of the present invention is at least 125 KJ / L. The latent heat of fusion of the composition of the present invention is preferably 130 KJ / L or more, and more preferably 140 KJ / L or more. Thus, the composition of the present invention can have a significantly higher latent heat of fusion than conventional cold storage agents.

[0012] The flash point of the composition of the present invention may be 93°C or higher when measured using a Cleveland open cup tester as specified in JIS K 2265.4. A flash point of 93°C or higher means that the composition does not fall under the flammable liquid category of the GHS classification. The flash point of the composition of the present invention is preferably 130°C or higher, and more preferably 140°C or higher.

[0013] The acid value of the composition of the present invention may be 2.0 or less when measured by the method specified in JIS K 2501.5. An acid value of 2.0 or less can suppress the generation of hydrogen due to deterioration and decomposition of the composition. The acid value of the composition of the present invention is preferably 1.7 or less, and more preferably 1.5 or less.

[0014] A cold storage agent or a cold heat storage agent is usually enclosed in an aluminum refrigeration cycle device before use. When the cold storage agent or the cold heat storage agent comes into contact with the refrigeration cycle device, aluminum ions may be generated. If the concentration of the generated aluminum ions becomes high, rust may form in the refrigeration cycle device or hydrogen may be generated, causing deformation of the refrigeration cycle device. Assuming that the cold-storage composition of the present invention is enclosed in an aluminum refrigeration cycle device, if an aluminum piece of a predetermined size placed in a sample bottle containing the same amount of distilled water as the composition of the present invention does not discolor after being left standing under predetermined conditions, the Al ion concentration in the water layer is usually 1.00 ppm or less, preferably 0.5 ppm or less, and more preferably 0.11 ppm or less. This can prevent rusting of the aluminum refrigeration cycle device and deformation of the aluminum refrigeration cycle device due to hydrogen generation.

[0015] The evaporation loss of the composition of the present invention after 72 hours at 50°C is usually 15% by mass or less, preferably 10% by mass or less. A large evaporation loss increases the possibility of deformation of the aluminum case, so a small evaporation loss is desirable. 50°C is the temperature at which the composition of the present invention is assumed to be used around a car air conditioner in midsummer.

[0016] [(C) Hydrogen generation inhibitor] The cold / heat storage composition of the present invention may further contain a hydrogen generation inhibitor. The hydrogen generation inhibitor that can be used in the present invention is preferably at least one selected from the group consisting of amine salts, sulfonates, phosphate esters, and mixtures thereof. These compounds are usually used as organic inhibitors (oil-soluble rust inhibitors) or passivating agents. Examples of the amine salt include fatty acid amine salts, aromatic carboxylic acid amine salts, and phosphoric acid ester amine salts, with fatty acid amine salts being preferred. The fatty acid constituting the fatty acid amine salt preferably includes a fatty acid having 4 to 22 carbon atoms, more preferably a fatty acid having 8 to 18 carbon atoms. The fatty acid may be a saturated fatty acid or an unsaturated fatty acid, and may further include a straight-chain fatty acid, a branched fatty acid, a cyclic fatty acid, or a hydroxy fatty acid. Specific examples include stearic acid, palmitic acid, myristic acid, lauric acid, isostearic acid, octylic acid, undecylenic acid, oleic acid, and hydroxystearic acid. Of these, octylic acid and oleic acid are preferred.

[0017] The amine constituting the fatty acid amine salt is not particularly limited, but preferably includes saturated or unsaturated amines having 1 to 42 carbon atoms, and more preferably saturated or unsaturated amines having 4 to 22 carbon atoms. Specific examples include octylamine, laurylamine, myristylamine, stearylamine, behenylamine, oleylamine, tallow alkylamine, hydrogenated tallow alkylamine, aniline, benzylamine, cyclohexylamine, diethylamine, dipropylamine, dibutylamine, diphenylamine, dibenzylamine, dicyclohexylamine, triethylamine, tributylamine, dimethyloctylamine, dimethyldecylamine, dimethylstearylamine, dimethyl tallow alkylamine, dimethyl hydrogenated tallow alkylamine, dimethyloleylamine, etc. Of these, hydrogenated tallow alkylamine and tributylamine are preferred. The fatty acid amine salts may be used alone or in combination of two or more. Particularly preferred are fatty acid amine salts obtained from octylic acid and tributylamine, fatty acid amine salts obtained from oleic acid and hardened tallow alkylamine, and mixtures thereof. Examples of the aromatic carboxylic acid amine salt include ammonium benzoate. Specific examples of the amine constituting the amine phosphate include tertiary alkylamines and aromatic amines.

[0018] Examples of the sulfonic acid component of the sulfonate include petroleum sulfonic acid, alkylnaphthalene sulfonic acid, and alkylbenzene sulfonic acid, and are composed of their amine salts and metal salts. Metal salts are preferred. Examples of amine salts include ammonium salts, diethylenetriamine salts, and ethylenediamine salts. Examples of metal salts include calcium salts, magnesium salts, sodium salts, potassium salts, lithium salts, and zinc salts. Preferred salts are calcium salts, sodium salts, and zinc salts. Zinc salts are particularly preferred. The sulfonates may be used alone or in appropriate combinations of two or more.

[0019] Examples of the phosphate ester constituting the phosphate amine salt include acidic phosphate ester and orthophosphate ester, with acidic phosphate ester being preferred. Specific examples of acidic phosphate esters include methyl acid phosphate, butyl acid phosphate, dibutyl phosphate, monobutyl phosphate, 2-ethylhexyl acid phosphate, isodecyl acid phosphate, and monoisodecyl phosphate. Specific examples of orthophosphate esters include trimethyl phosphate, triethyl phosphate, tributyl phosphate, tris(2-ethylhexyl) phosphate, triphenyl phosphate, tricresyl phosphate, trixylenyl phosphate, cresyl diphenyl phosphate, 2-ethylhexyl diphenyl phosphate, etc. The above phosphoric acid ester amine salts may be used alone or in appropriate combination of two or more.

[0020] The hydrogen generation inhibitor is preferably a combination of a fatty acid amine salt and a phosphate ester, or a combination of a metal sulfonate and a phosphate ester. A combination of a fatty acid amine salt and a phosphate ester is particularly preferred. Among these, it is preferred that the fatty acid amine salt is a salt of a fatty acid having 4 to 22 carbon atoms and a saturated or unsaturated amine having 1 to 42 carbon atoms, a fatty acid amine salt obtained from octylic acid and tributylamine, a fatty acid amine salt obtained from oleic acid and hardened tallow alkylamine, or a mixture thereof, and that the phosphate ester is an acidic phosphate ester selected from the group consisting of methyl acid phosphate, butyl acid phosphate, dibutyl phosphate, monobutyl phosphate, 2-ethylhexyl acid phosphate, isodecyl acid phosphate, and monoisodecyl phosphate. The ratio (mass ratio) of the fatty acid amine salt to the phosphate ester is preferably 10:90 to 90:10, more preferably 25:75 to 75:25, and even more preferably 40:60 to 60:40.

[0021] The hydrogen generation inhibitor is preferably contained in an amount that does not affect the latent heat of fusion of the base. Specifically, the total amount of the hydrogen generation inhibitor is preferably 0.01 to 10.0 mass%, more preferably 0.05 to 5.0 mass%, even more preferably 0.1 to 3.0 mass%, and particularly preferably 0.1 to 1.0 mass%, based on the total mass of the composition.

[0022] [Additives] The cold- and heat-storage composition of the present invention may contain additives that are commonly used in cold- and heat-storage agents, such as antioxidants, to the extent that they do not affect the latent heat of fusion of the base. As the antioxidant, a phenol-based antioxidant or an amine-based antioxidant is preferred, and a phenol-based antioxidant is more preferred. Examples of phenolic antioxidants include 2,6-di-tert-butyl-p-cresol (BHT), 2,2'-methylenebis(4-methyl-6-tert-butylphenol), 4,4'-butylidenebis(3-methyl-6-tert-butylphenol), 2,6-di-tert-butyl-phenol, 2,4-dimethyl-6-tert-butylphenol, tert-butylhydroxyanisole (BHA), 4,4'-butylidenebis(3-methyl-6-tert-butylphenol), 4,4'-methylenebis(2,3-di-tert-butylphenol), 4,4'-thiobis(3-methyl-6-tert-butylphenol), etc. Of these, 2,6-di-tert-butyl-phenol is preferred. Examples of amine-based antioxidants include Nn-butyl-p-aminophenol, alkyldiphenylamines, α-naphthylamines, N-phenyl-α-naphthylamines, and phenothiazines. Among these, alkyldiphenylamines are preferred, and dioctyldiphenylamine is particularly preferred. The above antioxidants may be used alone or in appropriate combination of two or more. The total amount of antioxidants to be added may be such that it does not affect the latent heat of fusion of the base, and is preferably 0.01% by mass to 10% by mass, more preferably 0.05% by mass to 5% by mass, and even more preferably 0.1% by mass to 0.9% by mass, based on the total mass of the composition.

[0023] [(E) Thickener] The cold / heat storage agent composition of the present invention may be made into a grease by adding a thickener. Examples of the thickener that can be used in the present invention include at least one selected from the group consisting of urea compounds, urethane compounds, carbon black, bentonite, and fumed silica. Examples of the urea compound include diurea compounds represented by the following formula (1). R1-NHCONH-R2-NHCONH-R3 (1) (In the formula, R1 and R3 may be the same or different and each represents a hydrocarbon residue having 4 to 20 carbon atoms, such as an aliphatic hydrocarbon group, an alicyclic hydrocarbon group, or an aromatic hydrocarbon group. R2 represents an aromatic hydrocarbon group having 6 to 15 carbon atoms.)

[0024] The diurea compound can be obtained, for example, by reacting an aromatic diisocyanate with an aromatic amine, an aliphatic amine, an alicyclic amine, or a mixture of two or more of these in a base oil. Specific examples of aromatic diisocyanates include tolylene diisocyanate, diphenylmethane diisocyanate, and naphthalene diisocyanate. Specific examples of aromatic amines include para-toluidine, aniline, and naphthylamine. Specific examples of aliphatic amines include octylamine, nonylamine, decylamine, undecylamine, dodecylamine, tridecylamine, tetradecylamine, pentadecylamine, hexadecylamine, heptadecylamine, octadecylamine, nonyldecylamine, and eicosylamine. Specific examples of alicyclic amines include cyclohexylamine. Among these, diurea compounds (aliphatic diurea compounds, alicyclic diurea compounds, or alicyclic aliphatic diurea compounds) obtained from aromatic diisocyanates and aliphatic amines, alicyclic amines, or mixtures thereof are preferred. Particularly preferred is a urea compound in which the aromatic diisocyanate is diphenylmethane diisocyanate and the aliphatic amine, alicyclic amine or mixture thereof is octadecylamine, cyclohexylamine or mixture thereof.

[0025] The urethane compound can be obtained by reacting the above diisocyanate with a monohydric alcohol having 4 to 20 carbon atoms in a base oil. The average primary particle size of the fumed silica is preferably 0.1 μm or less, more preferably 0.05 μm or less. Hydrophobized terminals such as dimethyl, trimethyl, or octyldimethylpolysiloxane are preferred. This thickener is preferably added by milling at temperatures below 80°C. If the base has a low flash point, the reaction process or heating above 80°C increases the risk of process hazards. In view of not affecting the latent heat of fusion of the base, carbon black and fumed silica are preferred, as they can turn the base into a grease in small amounts, and in view of aluminum resistance, thickeners selected from the group consisting of carbon black and hydrophobic fumed silica are preferred. The content of the thickener is preferably an amount that gives the grease a worked penetration of about 200 to 400, and is usually 1 to 30 mass %, and preferably 3 to 20 mass %. [Example]

[0026] <Preparation of Cold and Heat Storage Agent Composition> The cold and heat storage compositions of the examples and comparative examples were produced by putting the substances shown in Tables 1 to 3 (in the tables, the numerical values ​​for (A) to (E) are mass % based on the total mass of the composition) into a beaker, heating to 50°C, stirring, confirming that they were dissolved, and then allowing them to cool naturally to room temperature. The grease composition was prepared by adding a thickener to the cold and heat storage composition after natural cooling, and then rolling at room temperature using a three-roll mill. The obtained cold / heat storage composition was tested by the following methods, and the results are shown in Tables 1 to 3.

[0027] <Test Method> Melting point, freezing point and latent heat The melting point, freezing point, and latent heat of the cold storage composition were measured using a differential scanning calorimeter (DSC: DSC Q2000 manufactured by TA Instruments). Measurements were performed by cooling approximately 5 mg of a sample to -30°C or -20°C at a rate of 5°C / min and then heating to 40°C at a rate of 5°C / min. The extrapolated melting onset temperature of the melting peak was taken as the melting point, and the extrapolated crystallization onset temperature of the first crystallization peak was taken as the freezing point. The latent heat per weight (solid-liquid latent heat J / g) was calculated from the area of ​​the melting peak, and this was multiplied by the density to calculate the heat per volume. Because the latent heat used depends on the volume inside the container, the latent heat per volume (solid-liquid latent heat KJ / L) was calculated. ○Density g / cm 3 (15℃) Complies with JIS K 2249. ○Flash point (℃) Complies with JIS K 2265.4 (Cleveland open-type (abbreviated as "COC")). ○Acid value mgKOH / g Complies with JIS K 2501.5.

[0028] Al ion concentration (1) 8.5 ml of the cold / heat storage composition of the Examples and Comparative Examples is placed in a sample bottle. (2) Next, place a 40 x 12 mm aluminum piece into the sample bottle. (3) Finally, add 8.5 ml of distilled water to the sample bottle (cold storage agent: distilled water = 1:1 (volume ratio)). After adding to distilled water, if left to stand, the insolubility will cause the agent to separate into two layers due to their specific gravity (if no thickener is added, the lower layer will be distilled water and the upper layer will be the cold storage agent composition. If a thickener is added, the lower layer will be the cold storage agent composition and the upper layer will be distilled water). (4) Close the lid of the sample bottle and leave it in a 90°C thermostatic chamber for 72 hours, then visually inspect the surface of the aluminum piece for rust. No rust is considered a pass. The aqueous layer is collected with a syringe and the concentration of aluminum ions dissolved in the pure water is measured using ICP analysis. ICP analysis follows JIS K0116 General Rules for Optical Emission Analysis. Evaporation loss Approximately 50 g of the cold / heat storage composition was placed in a 100 ml beaker, weighed, and left to stand in a thermostatic bath at 50°C for 72 hours. The weight loss was then divided by the mass before the test and expressed as a percentage to obtain the evaporation loss. ○60 times unmixed consistency Comply with JIS K 2220 7.

[0029] [Table 1]

[0030] [Table 2]

[0031] [Table 3]

Claims

1. (A) 70 to 89.5 mass% of a dialkyl ether having a linear alkyl group selected from octyl ether or decyl ether, based on the total mass of the composition; (B) normal paraffin having 16 to 18 carbon atoms selected from normal hexadecane, normal heptadecane, or normal octadecane, in an amount of more than 3.0 mass% and less than 10.0 mass%, based on the total mass of the composition; (C) a hydrogen generation inhibitor in an amount of 0.1 to 1.0 mass % based on the total mass of the composition; and (D) an antioxidant in an amount of 0.1 to 0.9% by mass, based on the total mass of the composition; Contains A cold / heat storage composition having a melting point and a solidification point in the range of -13.0°C to +12.4°C as measured by DSC, and a latent heat of fusion per volume of 125 kJ / L or more.

2. 2. The cold / heat storage composition according to claim 1, which has a flash point of 93° C. or higher.

3. 3. The cold / heat storage composition according to claim 1, wherein (C) is at least one selected from the group consisting of amine salts, sulfonate salts, phosphate esters, and mixtures thereof.

4. (D) is selected from the group consisting of 2,6-di-tertiary butyl-p-cresol (BHT), 2,2'-methylene bis (4-methyl-6-tertiary butyl phenol), 4,4'-butylidene bis (3-methyl-6-tertiary butyl phenol), 2,6-di-tertiary butyl-phenol, 2,4-dimethyl-6-tertiary butyl phenol, tertiary butyl hydroxyanisole (BHA), 4,4'-butylidene bis (3-methyl-6-tertiary butyl phenol), 4,4'-methylene bis (2,3-di-tertiary butyl phenol), 4,4'-thiobis (3-methyl-6-tertiary butyl phenol), the cold storage heat storage agent composition according to any one of claims 1 to 3.

5. The cold / heat storage composition according to any one of claims 1 to 4, further comprising (E) at least one thickener selected from the group consisting of urea compounds, urethane compounds, carbon black, bentonite, and fumed silica.

6. An aluminum refrigeration cycle device in which the cold storage composition according to any one of claims 1 to 5 is enclosed.

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