A cold storage material composition, a cold storage body, and a method for producing a cold storage material composition.

Abstract

To provide a thermal storage material composition that is highly safe and has a large latent heat of fusion, and to provide a method for producing such a thermal storage material composition in high yield by a method with low environmental impact. [Solution] The solution contains a diester compound represented by formula (1), TIFF2026057926000008.tif26127 (In formula (1), R 1 R is an alkylene group having 2 to 10 carbon atoms. 2 and R 3 Each of these is an aliphatic alkyl group having 8 to 16 carbon atoms.) A cold storage material composition in which the proportion of peaks other than the main peak is 1.0 area % or less in gas chromatography analysis, and the melting point is 40°C or higher and 50°C or lower.

Description

[Technical Field]

[0001] The present invention relates to a cold storage material composition, a cold storage body, and a method for producing a cold storage material composition. [Background technology]

[0002] Some materials are used as cold storage materials by utilizing the latent heat exchange that occurs during the phase transition between liquid and solid. Such materials are also called phase change materials (PCMs). For example, Patent Document 1 discloses a cold storage material composition comprising n-paraffin with 12 to 50 carbon atoms and a thermoplastic elastomer containing styrene-(ethylene-styrene-butylene)-styrene block copolymer (S-(EB / S)-S). In the example of Patent Document 1, a gel-like composition consisting of 90% by mass of n-heptadecane and 10% by mass of S-(EB / S)-S is disclosed. The phase transition temperature of this composition is approximately 21°C.

[0003] Patent Document 2 discloses a method for producing diol diester compounds used as PCMs. Patent Document 2 discloses obtaining diol diester compounds by transesterifying a fatty acid alkyl ester having 6 to 30 carbon atoms with an alkanediol having 2 to 22 carbon atoms in the presence of a basic transesterification catalyst. The examples in Patent Document 2 describe the synthesis of various diol diester compounds by transesterification, with a yield of 63 to 78% and a melting temperature range of 39 to 77°C. [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2018-154796 [Patent Document 2] Special Publication No. 2018-504417 [Overview of the Initiative] [Problems that the invention aims to solve]

[0005] PCMs used as thermal storage materials and cooling components are desirable to be highly safe, undergo phase transitions at desired temperatures, and possess large latent heat. Furthermore, when manufacturing PCMs, it is desirable that the manufacturing process is environmentally friendly and can be carried out in high yield. The object of this invention is to provide a thermal storage material composition that is highly safe and has large latent heat of fusion, and to provide a method for manufacturing such a thermal storage material composition in high yield using an environmentally friendly method. [Means for solving the problem]

[0006] The thermal storage material composition according to this disclosure comprises a diester compound represented by formula (1), TIFF2026057926000002.tif26129 (In formula (1), R 1 R is an alkylene group having 2 to 10 carbon atoms. 2 and R 3 Each of these is an aliphatic alkyl group with 8 to 16 carbon atoms. In gas chromatography analysis, the proportion of peaks other than the main peak is 1.0 area % or less, and the melting point is between 40°C and 50°C.

[0007] The manufacturing method relating to this disclosure is a method for manufacturing the thermal storage material composition, An esterification step in which an aliphatic carboxylic acid having an alkyl group having 8 to 16 carbon atoms and a diol having 2 to 10 carbon atoms are dehydrated and condensed in the presence of a catalyst, The process includes a purification step of purifying the reaction mixture obtained by the esterification step. The aforementioned purification process is A first vacuum distillation step involves removing components containing unreacted substances under reduced pressure at a temperature of 100-230°C and a pressure of 6-0.1kPa, The method includes, after the first vacuum distillation step, a second vacuum distillation step in which water-containing components are distilled off while blowing steam at a temperature of 100 to 230°C and a pressure of 6 kPa or less. [Effects of the Invention]

[0008] According to the cold storage material composition of the present disclosure, a cold storage material with high safety and a large latent heat of fusion is provided. According to the manufacturing method of the composition containing the diester compound of the present disclosure, a cold storage material composition containing a diester compound with a large latent heat of fusion can be obtained with low environmental impact and high yield.

Brief Description of the Drawings

[0009] [Figure 1] FIG. 1 is an example of a gas chromatography analysis chart of the cold storage material composition of Example 1 according to the present disclosure. [Figure 2] FIG. 2 is an example of a gas chromatography analysis chart of the cold storage material composition of Comparative Example 1 outside the scope of the present disclosure.

Modes for Carrying Out the Invention

[0010] [Overview of the Embodiment] First, embodiments of the cold storage material composition and its manufacturing method according to the present disclosure will be listed and described. In this specification, unless otherwise specified, "A~B" representing a numerical range means "A or more and B or less".

[0011] The composition according to the present disclosure is a cold storage material composition containing a diester compound, and contains a diester compound represented by formula (1). TIFF2026057926000003.tif26129 (In formula (1), R 1 is an alkylene group having 2 to 10 carbon atoms, and each of R 2 and R 3 is an aliphatic alkyl group having 8 to 16 carbon atoms.) In the gas chromatography analysis of the composition according to the present disclosure, the ratio occupied by peaks other than the main peak is 1.0 area% or less, and the melting point is 40°C or more and 50°C or less.

[0012] Conventionally, as a cold storage material using PCM, those containing paraffin compounds are known (for example, Patent Document 1). The paraffin compound is mixed with a thermoplastic elastomer resin and used as a gel-like cold storage material composition. However, paraffin compounds having a melting point around 40 to 60°C have a flash point of 200°C or lower, and some PCMs containing such paraffin compounds fall under dangerous goods. The inventors have studied a safer cold storage material using PCM and found that by adopting a fatty acid ester compound, a cold storage material with a flash point of 250°C or higher that does not fall under dangerous goods and is more safe can be constituted. Furthermore, it has been found that a composition of a diester compound having a specific chemical structure, in which the area occupied by peaks other than the main peak in gas chromatography analysis is 1.0 area% or less and the melting point is 40°C or higher and 50°C or lower, has a large latent heat.

[0013] In the cold storage material composition, in the formula (1), R <00)00007>, R 2 and R 3 It is preferable that the sum of the carbon numbers of is 28 or more and 30 or less.

[0014] In the cold storage material composition, it is preferable that the acid value of the composition is 0.1 mgKOH / g or less.

[0015] The cold storage material according to the present disclosure is composed of a composition containing the diester compound. The composition according to the present disclosure has a large melting latent heat and is useful as a cold storage material. The composition is housed in a container and is suitably used as a cold storage body.

[0016] The manufacturing method according to the present disclosure is a method for manufacturing the cold storage material composition, An esterification step of subjecting an aliphatic carboxylic acid having an alkyl group with 8 to 16 carbon atoms and a diol having 2 to 10 carbon atoms to dehydration condensation in the presence of a catalyst, And a purification step of purifying the reaction mixture obtained by the esterification step. The purification step is A first vacuum distillation step involves removing components containing unreacted substances under reduced pressure at a temperature of 100-230°C and a pressure of 6-0.1kPa, The method includes, after the first vacuum distillation step, a second vacuum distillation step in which water-containing components are distilled off while blowing steam at a temperature of 100 to 230°C and a pressure of 6 kPa or less. According to the manufacturing method described herein, a thermal storage material composition with a large latent heat of fusion can be obtained in a highly industrially feasible manner and in high yield.

[0017] In the above manufacturing method, the catalyst may be tinnooxide. By using tinnooxide as a catalyst, dehydration condensation can be reliably carried out, and a thermal storage material composition with a large latent heat of fusion can be obtained in high yield.

[0018] In the above manufacturing method, a neutralization step and a washing step may be included between the first vacuum distillation step and the second vacuum distillation step. By performing neutralization and washing between the first vacuum distillation step and the second vacuum distillation step, a composition of the diester compound with high purity can be reliably obtained.

[0019] The following describes in more detail the thermal storage material composition and its manufacturing method related to this disclosure.

[0020] (Cold storage material composition) The cold storage material composition according to this disclosure may contain a diester compound and other components. Other components include, for example, unreacted products derived from the process of producing a diester compound such as a monoester obtained by reacting one molecule each of a raw material diol and an aliphatic carboxylic acid. In the composition according to this disclosure, the proportion of peaks other than the main peak detected when gas chromatography analysis is performed is 1.0 area % or less, and preferably 0.7 area % or less.

[0021] This section describes the gas chromatography (GC) analysis of cold storage material compositions. GC analysis can typically be performed under the following conditions and with the following equipment. However, analysis may be performed using other equipment and conditions, provided that equivalent measurement results can be obtained. • GC system: Gas chromatograph GC-2014 (manufactured by Shimadzu Corporation) • Detector: FID, 320℃ • Column: Agilent Technologies, Inc. DB-1 (30m x 0.25mmφ x 0.25μm) Column temperature: 150°C, heating rate 10°C / min, 320°C (holding time 15 min) Injection temperature: 300℃ • Carrier gas: Helium (linear velocity: 35.8 cm / sec) • Injection volume: 1.0 μl (split ratio: 45) • Sample preparation: Add 5.0g of acetone to 0.1g of the sample and shake to dissolve at room temperature.

[0022] In this specification, the main peak in a GC chart means a peak that occupies at least 80% (area percentage method) of the chart obtained by GC analysis and occupies at least twice the area of ​​the next largest peak. The main peak is preferably a single peak. In the compositions according to this disclosure, the proportion occupied by the main peak is preferably greater than 99% and at least 99.3% of the area.

[0023] The thermal storage material composition according to this disclosure has a melting point of 40°C or higher and 50°C or lower. Because the composition according to this disclosure has a melting point within this range and possesses a large latent heat of fusion, it is suitably used, for example, as a coolant for motors in mobility or as a heat transfer medium in heat exchangers. The melting point is a value measured, for example, by a DSC (Differential Scanning Calorimeter).

[0024] The cold storage material composition according to this disclosure preferably has an acid value of 0.1 mg KOH / g or less. The acid value of the composition is derived from the carboxylic acid used as a reaction raw material, and compositions in which the acid value has been reduced to the aforementioned range have sufficiently high purity and excellent storage stability, thermal stability, and hydrolysis stability.

[0025] The cold storage material composition according to this disclosure may contain a solvent, but is preferably solvent-free. If a solvent is included, the solvent may be, for example, xylene, cyclohexane, ethylcyclohexane, or a combination thereof. Furthermore, the composition may contain various additives such as antistatic agents, antioxidants, antibacterial and antifungal agents, stabilizers, dyes, pigments, and inorganic fine particles, to the extent that they do not affect the cold storage effect of the diester compound.

[0026] The cold storage material composition according to the present invention can be used as a cold storage material for various applications, and can be applied to coolants and heat exchangers in mobility, medical components, insulated containers, refrigerants, air conditioning equipment, etc. The cold storage material composition can also be contained in a container made of polyethylene or polyester and sealed to form a cold storage body. The container may be a transparent or translucent flexible or rigid resin container, or it may be an opaque resin container, a metal container, a tube, etc.

[0027] (Diester compounds) The compositions relating to this disclosure include a diester compound represented by formula (1). The diester compound represented by formula (1) is a diol diester compound. The composition may contain one or more diester compounds, but it is preferable to contain one. TIFF2026057926000004.tif26129 (In formula (1), R 1 R is an alkylene group having 2 to 10 carbon atoms. 2 and R 3 Each of these is an aliphatic alkyl group with 8 to 16 carbon atoms.

[0028] R 1R is a linear or branched alkylene group having 2 to 10 carbon atoms, and is preferably a linear alkylene group. 1 Specifically, examples include ethylene, propylene, butylene, pentylene, hexylene, heptylene, octylene, nonylene, and decylene groups. In other words, the diols constituting the diester compound may be ethanediol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,7-heptanediol, 1,8-octanediol, 1,9-nonanediol, and 1,10-decanediol. 1 It is more preferable that the carbon number is 4 to 10, and more specifically, it is more preferable that it is a butylene group, a hexylene group, or a desilene group.

[0029] R 2 and R 3 They may be the same or different from each other, but it is preferable that they be the same. 2 and R 3 Each of these is a linear or branched aliphatic alkyl group having 8 to 16 carbon atoms, and a linear aliphatic alkyl group is preferred. 2 and R 3 R is a residue derived from a carboxylic acid, 2 , R 3 Specifically, examples include octyl, nonyl, decyl, undecyl, dodecyl, tridecyl, tetradecyl, pentadecyl, and hexadecyl groups. The number of carbon atoms in the alkyl group may be even or odd. Examples of carboxylic acids constituting the diester compound represented by formula (1) include caproic acid, caprylic acid, capric acid, lauric acid, myristic acid, and palmitic acid. In other words, examples of diester compounds represented by formula (1) include caproic acid esters, caprylic acid esters, capric acid esters, lauric acid esters, myristic acid esters, and palmitic acid esters.

[0030] R 1 , R 2 and R 3The sum of the number of carbon atoms is preferably 28 or more and 30 or less. 1 , R 2 and R 3 The sum of the carbon numbers is the total number of carbon atoms in the diester compound. A total carbon number of 28 to 30 is more preferable. When the total carbon number is in this range, a cold storage material composition with a melting point in the range of 40 to 50°C and a large latent heat of fusion can be obtained.

[0031] (Manufacturing method) The compositions described herein can be produced by an esterification reaction involving the dehydration condensation of a diol compound and a carboxylic acid. In the case of esterification by dehydration condensation, the only component discharged from the reaction system is water. By employing esterification by dehydration condensation, the environmental impact of production can be reduced compared to the case of transesterification.

[0032] The manufacturing method according to this disclosure includes a raw material preparation step, an esterification step, and a purification step. In the raw material preparation step, a carboxylic acid and a diol compound corresponding to the target diester compound are added to the reaction vessel. Examples of carboxylic acids and diol compounds include those mentioned above. The charging ratio (molar ratio) of carboxylic acid to diol compound is often 220:100 to 200:100, and preferably 210:100 to 201:100. An esterification catalyst is also added to the reaction vessel. Any known catalyst can be selected and used as the esterification catalyst, and there are no particular limitations, but for example, tin monooxide, alkyl titanate, PTS, etc. can be used. In addition to the carboxylic acid, diol compound, and catalyst, it is also preferable to add an azeotrope. When an azeotrope is added, an organic solvent with a boiling point of about 80 to 150°C can be used as the azeotrope, and specifically, xylene, cyclohexane, ethylcyclohexane, etc. can be used.

[0033] The esterification process can be carried out at a temperature of 100-230°C and under reduced pressure of approximately 100-6 kPa. The reaction time is not particularly limited, but it may be 3-10 hours, and more preferably 3-8 hours from the viewpoint of oxidative degradation. The progress of the reaction can be confirmed by the amount of reaction product water, and the esterification reaction can be terminated when no more reaction product water is distilled off.

[0034] After esterification is complete, a purification process is carried out. In the purification process, low-boiling point components, including azeotropes and unreacted substances, are removed by distillation at a temperature of 100-230°C under a high vacuum of 6-0.1 kPa (first vacuum distillation step). Then, while maintaining a temperature of 50-95°C, an aqueous sodium hydroxide solution is added to neutralize any remaining acidic components. Next, while maintaining a temperature of 50-95°C, an appropriate amount of warm water is added to remove water-soluble impurities. Finally, under a reduced pressure of 6 kPa or less, steam is blown in while maintaining a temperature of 100-230°C to remove water-containing components (second vacuum distillation step). High-purity diester compounds can be obtained through these steps.

[0035] The above manufacturing method can yield a diester compound with few impurities and a large latent heat of fusion. The obtained diester compound is preferably used as a cold storage material composition. [Examples]

[0036] Next, the present invention will be described in more detail based on examples, but the present invention is not limited to such examples.

[0037] [Example 1] (Synthesis of cold storage material composition) In a 1 L four-necked flask equipped with a thermometer, decanter, stirring blade, and reflux condenser, 368 g (1.84 mol) of lauric acid, 106 g (0.90 mol) of 1,6-hexanediol, and 0.4 g of tin monooxide (manufactured by Wako Pure Chemical Industries, Ltd.) as an esterification catalyst were added. Furthermore, 30 g of xylene was added as an azeotrope, and the esterification reaction was carried out at a reaction temperature of 230 °C. The reaction pressure was adjusted from atmospheric pressure to 53 kPa. The pressure was gradually reduced, and the reaction was carried out while refluxing the lauric acid to remove the water product from the system until the theoretical water product (32g) was produced. After the reaction, the excess lauric acid was removed from the system by gradually reducing the pressure from 53 kPa to 1 kPa at 230°C. Subsequently, an aqueous sodium hydroxide solution (prepared from 10 g of sodium hydroxide and 220 g of water) was added at 80°C and neutralized by stirring for 30 minutes. After that, the organic layer was washed five times with 2 liters of 80°C warm water. Then, to remove the water contained in the system, the temperature was raised to 190°C, the pressure was reduced to 6 kPa, and steam was blown in while taking care to avoid bumping. The mixture was then cooled to 90°C, 2.6 g of activated alumina was added, and the mixture was stirred for 30 minutes under reduced pressure of 0.4 kPa. The mixture was filtered using a Kiriyama funnel to obtain 370 g of 1,6-hexanediol dilaurate (compound 1) in 85% yield. The acid value of the obtained 1,6-hexanediol dilaurate was 0.05 mg KOH / g.

[0038] (evaluation) The freezing point, melting point, flash point, and latent heat of fusion of the composition containing compound 1 obtained by the above manufacturing method were measured by the following methods. Gas chromatography analysis was also performed. • Measurement of the freezing point The freezing point was measured using a differential calorimetry analyzer DSC-60A manufactured by Shimadzu Corporation. 10 mg of the sample was placed in a sealed aluminum pan manufactured by the same company and held at 10°C for 10 minutes under a nitrogen flow of 50 ml / min. Then, the temperature was increased from 10°C to 80°C at a heating rate of 5°C / min, cooled from 80°C to 10°C at a cooling rate of 5°C / min, and then heated again from 10°C to 80°C at a heating rate of 5°C / min. The temperature indicated by the peak top before the melting point peak in the 2nd run was defined as the freezing point. • Measurement of melting point The melting point was measured using a differential calorimetry system DSC-60A manufactured by Shimadzu Corporation. 10 mg of the sample was placed in a sealed aluminum pan manufactured by the same company and maintained at 10°C for 10 minutes under a nitrogen flow of 50 ml / min. The temperature was then increased from 10°C to 80°C at a heating rate of 5°C / min, cooled from 80°C to 10°C at a cooling rate of 5°C / min, and then heated again from 10°C to 80°C at a heating rate of 5°C / min. The endothermic peak during the second run was observed. The temperature indicated by the peak top was defined as the melting point. • Measurement of flash point The flash point was measured in accordance with JIS-K-2265-4 (2007) using an automatic flash point tester (Cleveland open type) (manufactured by Yoshida Scientific Instruments Co., Ltd., device name: aco-8). • Measurement of latent heat of fusion The latent heat of fusion was measured using a differential calorimetry analyzer DSC-60A manufactured by Shimadzu Corporation. A 10 mg sample was placed in a sealed aluminum pan manufactured by the same company and maintained at 10°C for 10 minutes under a nitrogen flow of 50 ml / min. The temperature was then increased from 10°C to 80°C at a heating rate of 5°C / min, cooled from 80°C to 10°C at a cooling rate of 5°C / min, and then increased again from 10°C to 80°C at a heating rate of 5°C / min. The endothermic peak in the 2nd run was defined as the latent heat of fusion, representing the heat quantity in the range from the starting point of 13°C to the ending point of 80°C. • Gas chromatography analysis Gas chromatography analysis was performed using the following equipment and conditions. • GC system: Gas chromatograph GC-2014 (manufactured by Shimadzu Corporation) • Detector: FID, 320℃ • Column: Agilent Technologies, Inc. DB-1 (30m x 0.25mmφ x 0.25μm) Column temperature: 150°C, heating rate 10°C / min, 320°C (holding time 15 min) Injection temperature: 300℃ • Carrier gas: Helium (linear velocity: 35.8 cm / sec) • Injection volume: 1.0 μl (split ratio: 45) • Sample preparation: 0.1 g of the sample was mixed with 5.0 g of acetone at room temperature and dissolved. From the resulting gas chromatography analysis chart, we confirmed the area percentage (%) of the main peak.

[0039] [Example 2] A composition containing a diester compound was prepared in the same manner as in Example 1, except that 373.6 g (2.17 mol) of capric acid was used instead of lauric acid as the starting carboxylic acid for esterification, and 180.0 g (1.03 mol) of 1,10-decanediol was used instead of 1,6-hexanediol as the starting diol. The obtained decanediol dicaprate (compound 2) had an acid value of 0.09 mg KOH / g. Similar to Example 1, the freezing point, melting point, flash point, and latent heat of fusion were measured for the composition containing compound 2. Gas chromatography analysis was also performed.

[0040] [Example 3] A composition containing a diester compound was prepared in the same manner as in Example 1, except that 817.3 g (4.08 mol) of lauric acid was used as the starting carboxylic acid for esterification, and 180.2 g (2.0 mol) of 1,4-butanediol was used instead of 1,6-hexanediol as the starting diol. The obtained butanediol dilaurate (compound 3) had an acid value of 0.02 mg KOH / g. Similar to Example 1, the freezing point, melting point, flash point, and latent heat of fusion were measured for the composition containing compound 3. Gas chromatography analysis was also performed.

[0041] [Comparative Example 1] 900.0 g (4.5 mol) of lauric acid as the starting carboxylic acid for esterification and 180.2 g (2.0 mol) of 1,4-butanediol as the starting diol were charged, and 0.5 g of p-toluenesulfonic acid was added as an ester catalyst. The esterification reaction was carried out at a reaction temperature of 120°C. A composition containing butanediol dilaurate (compound 3) was obtained as the ester. After the esterification reaction, the removal of excess lauric acid by distillation was omitted, and the neutralization, washing, and steam blowing steps were also omitted. As in Example 1, the freezing point, melting point, flash point, and latent heat of fusion of the composition containing compound 3 were measured. Gas chromatography analysis was also performed.

[0042] [Comparative Example 2] A composition containing a diester compound was prepared in the same manner as in Example 1, except that 419.3 g (1.84 mol) of myristic acid was used instead of lauric acid as the starting carboxylic acid for esterification, and 55.9 g (0.9 mol) of ethylene glycol was used instead of 1,6-hexanediol as the starting diol. The obtained ethylene glycol dimyristylate (compound 4) had an acid value of 0.30 mg KOH / g. Similar to Example 1, the freezing point, melting point, flash point, and latent heat of fusion were measured for the composition containing compound 4. Gas chromatography analysis was also performed.

[0043] [Comparative Example 3] Synthesis of butanediol dilaurate by transesterification method Butanediol dilaurate (compound 3) was synthesized according to the method described in Example 1 of Japanese Patent Publication No. 2018-504417. Specifically, methyl laurate was used as the starting carboxylate and 1,4-butanediol as the starting diol. 42.9 g of methyl laurate was placed in a reaction vessel and heated to 120°C. 0.21 g of KOH powder was added to the methyl laurate and stirred until homogeneous to obtain a mixture. Subsequently, 9.13 g of 1,4-butanediol was slowly added to the mixture. The resulting methanol was distilled off the system under atmospheric pressure, and then further discharged under reduced pressure. After no further methanol discharge was observed, the reaction mixture was cooled. The reaction mixture was dissolved in acetone, mixed with Celite by stirring, and then filtered by suction to obtain a colorless, transparent liquid. The diester compound was obtained by recrystallization from the acetone.

[0044] [Comparative Example 4] Synthesis of butanediol dilaurate by biotransformation reaction Butanediol dilaurate (compound 3) was synthesized by referring to the method described in Biotechnology Letters (1996), (18) 5, 541-546. Specifically, a microemulsion was prepared by adding 1,4-butanediol and lauric acid at the same concentrations to an isooctane solution containing 0.1 M bis(2-ethylhexyl)sodium sulfosuccinate (AOT). A reaction mixture was prepared by adding 25 mM Tris / HCl buffer (pH 8.0) to this mixture to obtain a w0 value (w0 = [H2O] / [AOT]) of 10. The biotransformation reaction was carried out by adding lipase at a concentration of 0.04 mg / mL to this reaction mixture. The reaction was carried out at 25°C.

[0045] Table 1 summarizes the composition and acid value of the diester compounds constituting the compositions of Examples 1-3 and Comparative Examples 1-4. Table 2 summarizes the freezing point, melting point, flash point, yield, latent heat of fusion, and presence or absence of impurity peaks for the compositions of Examples 1-3 and Comparative Examples 1-4. Figure 1 shows the gas chromatography analysis chart for Example 1, and Figure 2 shows the gas chromatography analysis chart for Comparative Example 1.

[0046] [Table 1]

[0047] [Table 2]

[0048] As shown in Tables 1 and 2, the compositions of Examples 1 to 3 according to this disclosure all had flash points of 254°C or higher, and higher than 250°C. Furthermore, their melting points were in the range of 40°C to 50°C, and their latent heat of fusion exceeded 160 J / g. In addition, their yields exceeded 80%.

[0049] On the other hand, the composition of Comparative Example 1, which had an impurity peak area of ​​12.3%, had a large latent heat of fusion, but also two melting point peaks, one of which was below 40°C. The composition of Comparative Example 2, which had a melting point exceeding 60°C, lacked sufficient latent heat of fusion. The freezing point had peaks at 35.9°C and 40.0°C, indicating a large difference between the melting point and the freezing point. The composition of Comparative Example 3, prepared by transesterification, had an impurity peak area of ​​1.8% and a melting point of 47.0°C. Its yield was 72%, which was lower than that of Examples 1-3. It also had a lower latent heat of fusion than the composition of Example 3, which contained the same compound 3. The composition of Comparative Example 4, prepared by a biotransformation reaction, had an impurity peak area of ​​5.2% and a melting point of 47.1°C. Its yield was 75%, which was lower than that of Examples 1-3. It also had a lower latent heat of fusion than the composition of Example 3, which contained the same compound 3.

[0050] The embodiments disclosed herein should be understood to be illustrative in all respects and not restrictive in any way. The scope of the present invention is defined by the claims and is intended to include all modifications in the sense and scope equivalent to the claims.

Claims

1. The diester compound represented by formula (1) is included, (In formula (1), R １ R is an alkylene group having 2 to 10 carbon atoms. ２ and R ３ Each of these is an aliphatic alkyl group having 8 to 16 carbon atoms. In gas chromatography analysis, the proportion of peaks other than the main peak is 1.0 area % or less. Its melting point is between 40°C and 50°C. Cold storage material composition.

2. In the above formula (1), R １ , R ２ and R ３ The sum of the number of carbon atoms is between 28 and 30. The cold storage material composition according to claim 1.

3. The acid value of the above composition is 0.1 mg KOH / g or less. The cold storage material composition according to claim 1.

4. A cold storage body comprising a cold storage material composition according to any one of claims 1 to 3 contained in a container.

5. An esterification step in which an aliphatic carboxylic acid having an alkyl group having 8 to 16 carbon atoms and a diol having 2 to 10 carbon atoms are dehydrated and condensed in the presence of a catalyst, The process includes a purification step of purifying the reaction mixture obtained by the esterification step, The aforementioned purification process is A first vacuum distillation step involves removing components containing unreacted substances under reduced pressure at a temperature of 100 to 230°C and a pressure of 6 to 0.1 kPa, After the first vacuum distillation step, a second vacuum distillation step is performed in which water-containing components are removed while blowing steam at a temperature of 100 to 230°C and a pressure of 6 kPa or less. A method for producing the cold storage material composition according to any one of claims 1 to 3, including

6. The catalyst is tin monooxide. A method for producing the cold storage material composition according to claim 5.

7. Between the first vacuum distillation step and the second vacuum distillation step, a neutralization step and a washing step are included. A method for producing the cold storage material composition according to claim 6.

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