Encapsulates
The invention discloses a microencapsulated phase change material having a specific Thermal Efficiency Index (TEI). TEI=α( RΔT )*β( RΔH )*γ( RMP )*δ( RTGA @180)*∈( RFW ) The problem of achieving effective and efficient microencapsulated phase change material can be solved to yield a commercially useful material having the described combination of physical and chemical characteristics based on the parameters described in the specification. Microcapsules according to the invention are highly effective at delivering enhanced thermal performance as compared to conventional microcapsules.
1. A microencapsulated phase change material comprising a particle comprising a core material and a wall material selected from the group consisting of polyacrylate, polymethacrylate, polyamine, polyurea, polyurethane, melamine formaldehyde, and mixtures thereof, that surrounds the core material, the particle having a Thermal Efficiency Index of at least 10,000; wherein said particle's core material comprises from 50 to 97 wt % of a methyl ester derived from palm oil, from 0.1 to 20 wt % of a straight chain alkane and from 0.1 to 25 wt % of a wax.
2. The microencapsulated phase change material of claim 1 , wherein the wax is selected from the group of waxes consisting of alkane wax, polyethylene wax, carnauba wax, candelilla wax, vegetable wax, beeswax and paraffin wax.
3. The microencapsulated phase change material according to claim 2 , wherein the core material comprises:
from 50 to 95 wt % of methyl palmitate;
from 0.1 to 20 wt % of octacosane; and
from 0 to 40 wt % of polyethylene wax.
4. The microencapsulated phase change material of claim 1 , wherein said particle comprises at least 1 wt % of the core material.
5. The microencapsulated phase change material of claim 1 , wherein said particle comprises from about 20 to about 95 wt % of the core material.
6. The microencapsulated phase change material of claim 1 , wherein said particle comprises from about 50 to about 90 wt % of the core material.
7. The microencapsulated phase change material according to claim 1 , having a differential scanning calorimetric melt point peak T 1 of the microencapsulated phase change material of not more than 30° C. and a resolidification peak T 2 of not less than 18° C., and wherein the absolute value of the difference between the respective melt point peak T 1 and resolidification peak T 2 is not more than 10° C.
8. The microencapsulated phase change material according to claim 7 , wherein the methyl ester is selected from methyl laurate, methyl myristate, methyl palmitate, methyl stearate, or methyl oleate.
9. The microencapsulated phase change material according to claim 7 , wherein the phase change material has a latent heat of at least 165 Joules per gram.
10. The microencapsulated phase change material according to claim 1 , having a differential scanning calorimetric melt point peak T 1 of the microencapsulated phase change material of not more than 30° C. and a resolidification peak T 2 of not less than 18° C., and wherein the absolute value of the difference between the respective melt point peak T 1 and resolidification peak T 2 is not more than 10° C.
11. The microencapsulated phase change material according to claim 10 , wherein the core material comprises a blend of methyl palmitate, octacosane and alkane wax.
12. The microencapsulated phase change material according to claim 10 , wherein the core material comprises:
(A) 55 to 95 wt % of methyl palmitate;
(B) 0.1 to 10 wt % of octacosane; and
(C) 0 to 30 wt % of one or more additional phase change materials other than phase change materials (A) and (B),
wherein the weight percent of (A), (B), and (C) is based on the total weight of the phase change material.
13. The microencapsulated phase change material according to claim 12 , wherein the latent heat storage density on a volumetric basis is greater than 165 Joules per gram.
14. An article of manufacture incorporating the microencapsulated phase change material according to claim 1 .
15. The article of manufacture according to claim 14 , wherein the article is selected from textiles, foams, pillows, mattresses, bedding, cushions, cosmetics, medical devices, packaging, cooling fluids, wallboard, and insulation.