PHASE CHANGE MATERIAL

Abstract

This invention describes a phase change material being 1,3-propanediol ester where the 1,3-propanediol ester can be either a 1,3-propanediol monoester or a 1,3-propanediol diester. This invention further describes the use of 1,3-propanediol ester as a phase change material for releasing or absorbing latent heat during melting or crystallization. This invention also describes the use of the phase change material for use in non-food and food applications.

Claims

1. A phase change material comprising 1,3-propanediol fatty acid ester.

2. The phase change material according to claim 1, characterized in that the 1,3-propanediol fatty acid ester is a monoester.

3. The phase change material according to claim 1, characterized in that the 1,3-propanediol fatty acid ester is a diester.

4. The phase change material according to any of the preceding claims, characterized in that said ester comprises fatty acids having a chain length of 2-24 carbon atoms.

5. The phase change material according to any of the preceding claims, characterized in that at least one of said fatty acids is linear.

6. The phase change material according to claim 5, characterized in that at least one of said fatty acids is linear and saturated.

7. The phase change material according to any of the preceding claims, characterized in that said phase change material has a high heat of fusion of between 100-250 J/g when measured by DSC at a heating rate of 1° C./min, such as between 150-200 J/g when measured by DSC at a heating rate of 1° C./min.

8. The phase change material according to any of the preceding claims, characterized in that said phase change material has a high heat of fusion higher than 50 J/g when measured by DSC at a heating rate of 1° C./min, such as higher than 100 J/g when measured by DSC at a heating rate of 1° C./min, such as higher than 150 J/g when measured by DSC at a heating rate of 1° C./min, such as higher than 200 J/g when measured by DSC at a heating rate of 1° C./min.

9. The phase change material according to any of the preceding claims, characterized in that said phase change material has a phase transition temperature range of between 1-20° C., such as a phase transition temperature range of between 1-15° C., such as a phase transition temperature range of between 1-10° C., such as a phase transition temperature of between 3-7° C.

10. The phase change material according to any of the preceding claims, characterized in that said phase change material further comprises a thermal stabilizer.

11. The phase change material according to any of the preceding claims, characterized in the said phase change material further comprises seed additives for reducing supercooling.

12. Use of 1,3-propanediol fatty acid ester as a phase change material as described in any of the claims 1-11 for releasing or absorbing latent heat during crystallization or melting.

13. A use of a phase change material as described in any of the claims 1-11 in non-food applications such as automotive, construction materials, textiles, shoes, protective equipment, medical applications, food applications such as food packaging and/or food formulations.

14. A temperature regulating article comprising a phase change material, said phase change material being as described in claims 1-11.

15. A temperature regulating article according to claim 14, comprising a phase change material, said phase change material being described in claims 1-11 having a composition that result in properties satisfying the need of the application wherein, said properties being the melting range and heat of fusion in J/g measured by DSC at a heating rate of 1° C./min.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0064] FIG. 1A illustrates the molecular structure of the fatty acid monoester 1,3-propanediol;

[0065] FIG. 1B illustrates the molecular structure of the fatty acid monoester 1,2-propanediol (propylene glycol);

[0066] FIG. 1C illustrates the molecular structure of the fatty acid diester 1,3-propanediol;

[0067] FIG. 1D illustrates the molecular structure of the fatty acid diester 1,2-propanediol (propylene glycol);

[0068] FIG. 2 illustrates phase transition temperatures and heat temperatures and heat fusion of 1,3-propanediol fatty acid diesters;

[0069] FIG. 3 illustrates an overlay of measurements of melting temperature range vs heat of fusion for 1,2-propanediol (A); 1,2-propanediol monolaurate (B); 1,3-propanediol monolaurate (C); and 1,3-propanediol monolaurate (D);

[0070] FIG. 4 illustrates an overlay of measurements of melting temperature range vs heat of fusion for 1,3-propanediol dibehenate (A); 1,3-propanediol dibehenate (B); 1,2-propandediol dibehenate (C); and 1,2-propanediol dibehenate (D);

[0071] FIG. 5A illustrates a DSC measurement (cooling curve) without seed addition (100 wt % 1,3-propandiol dicaprylate);

[0072] FIG. 5B illustrates a DSC measurement (cooling curve) with seed addition (97 wt % 1,3-propane diol dicaprylate+3 wt % 1,3-propanediol dibehenate).

EXAMPLES

Material and Methods

Compounds

[0073] 1,3-propanediol esters were produced by esterification of 1,3-propanediol with fatty acids similar to the synthesis of 1,3-propanediol dibehenate as described below.

[0074] 2 kg of behenic acid, 186 g of 1,3-propanediol and 2.81 g of magnesium stearate were mixed by mechanical stirring at 180° C. in a 5 L 3-neck reaction flask equipped with a vigreux column, a condenser and a connection to a vacuum pump. At this temperature water started to form and condensed in the condenser. The reaction was performed in a nitrogen atmosphere. Heating was continued carefully until a reaction temperature between 200-210° C. was reached. The reaction was kept at 205° C. under nitrogen until an acid value of AV=27 was reached. Subsequently, the reaction mixture was cooled to 175° C. and neutralized with phosphoric acid. Stirring at this temperature was continued for 15 minutes, after which the reaction mixture was cooled to 100° C. Clarcell filter aid was added and the mixture was poured into a pre-heated Büchner funnel at 110° C. to form a filter-cake. The remaining product was filtered at 100° C. at a pressure of 500 mBar. Surplus of fatty acid and monoester were distilled off at 205° C. at a pressure of 1×10.sup.−3 mBar. The resulting residue contained the 1,3-propanediol dibehenate product. The slightly yellowish product was further purified by a short path distillation under vacuum at 278° C. (short path distillation unit KD-L5). The final product was applied as bulk material or as microbeads obtained by spray cooling.

Differential Scanning Calorimetry (DSC) Measurements

[0075] The characterization of the phase change materials has been performed using a dynamic scanning calorimeter (Metier Toledo DSC822). For each measurement aluminum standard pans with a volume of 40 microliter have been used to contain 1-3 mg of the sample. The temperature profile was typically heating from 25° C. to 80° C. at 1° C./min (heat 1), C1: cooling from 80° C. to 20° C. at 1° C./min (cool 1), followed by subsequent heating from 20° C. to 80° C. at 1° C./min (heat 2). Depending on the type of PCM and the particular melting temperatures, alternatively higher or lower temperatures or heating and cooling rates have been applied (e.g. 10° C./min).

[0076] The melting temperatures and latent heat were determined after thermal equilibration from the 2.sup.nd heat melting curves.

[0077] All measurements were performed in duplicates.

II. Results

Phase Change Material Characteristics of 1,3 Propanediol Esters

[0078] Different 1,3-propanediol esters of saturated fatty acids with chain lengths of 8, 10, 12, 16, and 22 carbon atoms were obtained, i.e. 1,3-propanediol dibehenate, 1,3-propanediol dipalmitate, 1,3-propanediol dilaurate, 1,3-propanediol dicaprate, 1,3-propanediol dicaprylate, as well as 1,3-propanediol monolaurate.

[0079] The products show typical PCM properties, such as high latent heat and narrow melting temperature ranges (FIG. 2 and Table 1) as measured by DSC. This is most likely to be caused by a more regular packaging during crystallization owing to their more linear structure.

TABLE-US-00001 TABLE 1 Phase transition temperatures and heat of fusion of 1,3-propandiol fatty acid esters 1,3-propanediol Fatty acid Melting Heat of ester chain length temperature (° C.).sup.1, 2 fusion (J/g).sup.1, 3 1,3-propanediol 8 6 126 dicaprylate 1,3-propanediol 10 24 146 dicaprate 1,3-propanediol 12 37 162 dilaurate 1,3-propanediol 12 24 155 monolaurate 1,3-propanediol 16 57 190 dipalmitate 1,3-propanediol 22 70.5 197 dibehenate .sup.1Represent the average of measurements performed in duplicates. .sup.2Melting temperature equals peak temperature of the DSC measurements. .sup.3Heat of fusion equals Normalized integral of the DSC measurements.

[0080] As an example Table 2 shows the values obtained in the separate two measurements of 1,3-propanediol dipalmitate by DSC.

TABLE-US-00002 FIG. Peak no. Integral Normalized integral Onset Peak Left limit Right limit 1,3-propanediol 1.sup.st run −327.21 mJ −189.14 Jg{circumflex over ( )}−1 56.49° C. 56.67° C. 45.48° C. 60.23° C. dipalmitate 2.sup.nd run −355.42 mJ −190.06 Jg{circumflex over ( )}−1 56.48° C. 56.69° C. 45.24° C. 60.20° C.

[0081] Table 2 shows duplicate measurements of 1.3-propanediol dipalmitate.

Comparison Between 1,3-Propanediol Monolaurate and 1,2-Propanediol Monolaurate

[0082] Comparative studies of 1,3-propanediol monolaurate and 1,2-propanediol monolaurate show that 1,2-propanediol monolaurate (FIG. 3 and Table 3) exhibit a larger temperature melting range and a lower latent heat than 1,3-propanediol monolaurate (FIG. 3 and Table 3). Thus, 1,2-propanediol monolaurate cannot be used as phase change material like 1,3-propanediol monolaurate.

[0083] Table 3 shows the values of the integrals from Figure 3.

TABLE-US-00003 Curve Peak no. Integral Normalized integral Onset Peak Left limit Right limit A* 1 −145.24 mJ −110.03 Jg{circumflex over ( )}−1 3.82° C. 5.06° C. −7.06° C. 7.29° C. B* 1 −95.66 mJ −112.54 Jg{circumflex over ( )}−1 3.86° C. 5.11° C. −7.06° C. 7.27° C. C** 1 −316.78 mJ −156.05 Jg{circumflex over ( )}−1 22.54° C.  23.91° C.   4.77° C. 26.47° C.  D** 1 −131.70 mJ −154.94 Jg{circumflex over ( )}−1 24.22° C.  24.76° C.  12.96° C. 27.13° C.  *1,2-propanediol monolaurate **1,3-propanediol monolaurate

Comparison Between 1,3-Propanediol Dibehenate and 1,2-Propanediol Dibehenate

[0084] Comparative studies of 1,3-propanediol dibehanate and 1,2-propanediol dibehenate show that 1,2-propanediol dibehenate (FIG. 4 curves C & D and Table 4) exhibits a much larger temperature melting range and a lower latent heat than 1,3-propanediol dibehenate (FIG. 4 curves A & B and Table 4). Thus, 1,2-propanediol dibehenate cannot be used as phase change material like 1,3-propanediol dibehanate.

[0085] Table 4 shows the values of the integrals from Figures 4.

TABLE-US-00004 Curve Peak no. Integral Normalized integral Onset Peak Left limit Right limit A* 1 −751.48 mJ −195.70 Jg{circumflex over ( )}−1 68.43° C. 70.77° C. 28.83° C. 79.78° C. B* 1 −631.92 mJ −195.64 Jg{circumflex over ( )}−1 68.57° C. 71.06° C. 29.00° C. 79.85° C. C** 1 −14.92 mJ −5.04 Jg{circumflex over ( )}−1 16.96° C. 26.51° C. 15.83° C. 35.11° C. 2 −44.49 mJ −15.03 Jg{circumflex over ( )}−1 54.31° C. 56.76° C. 46.67° C. 57.75° C. 3 −388.13 mJ −131.13 Jg{circumflex over ( )}−1 63.12° C. 66.66° C. 61.39° C. 73.60° C. D** 1 −14.53 mJ −5.32 Jg{circumflex over ( )}−1 17.65° C. 26.53° C. 15.85° C. 35.13° C. 2 −39.25 mJ −14.38 Jg{circumflex over ( )}−1 54.16° C. 56.67° C. 46.70° C. 57.68° C. 3 −363.01 mJ −132.97 Jg{circumflex over ( )}−1 63.10° C. 66.72° C. 61.32° C. 73.77° C. *1,3-propanediol dibehenate **1,2-propanediol dibehenate

Addition of Seed Additives

[0086] The higher the melting temperature, the higher is the heat of fusion. 1,3-propanediol diesters of short and medium chain length fatty acids show larger supercooling than long chain fatty acid esters (as shown in FIGS. 4 and 5). This is for instance the case when comparing the much larger supercooling of 1,3-propandiol dicaprylate (FIG. 5) with the marginal supercooling of 1,3-propanediol dibehenate (FIG. 4). Overall the samples show a solid-liquid transition over narrow temperature ranges and only little or no supercooling, which is in accordance with other fatty acid esters (see reference K. Pielichowska, Progress in Materials Science 65 (2014), page 79).

[0087] Supercooling of 1,3-propanediol dicaprylate was measured on pure caprylate (FIG. 5A and Table 5) and on 1,3-propanediol dicaprylate comprising 3 wt % 1,3-propanediol dibehenate (FIG. 5B and Table 5). The 1,3-propanediol dibehenate functions as a seed additive and effectively suppress supercooling of the short chain fatty ester diesters of 1,3-propanediol.

[0088] Table 5 shows the values of the peaks from Figure 5A-B.

TABLE-US-00005 FIG. Peak no. Integral Normalized integral Onset Peak Left limit Right limit 5A* Left (A) 366.43 mJ 122.14 Jg{circumflex over ( )}−1 −8.63° C. 2.99° C. −10.72° C.  −8.27° C. Right (B) 369.67 mJ 121.20 Jg{circumflex over ( )}−1 −6.97° C. 3.98° C. −9.48° C. −6.78° C. 5B** Top (A) 361.58 mJ 120.13 Jg{circumflex over ( )}−1  0.17° C. 8.24° C. −2.23° C. −31.67e.sup.−03° C. Bottom (B) 374.84 mJ 119.76 Jg{circumflex over ( )}−1  0.24° C. 8.71° C. −2.25° C. 3.40e.sup.−03° C. *100 wt % 1,3-propanediol dicaprylate **97 wt % 1,3-propanediol dicaprylate comprising 3 wt % 1,3-propanediol dibehenate