Dry powder mixes comprising phase change materials

• US 5,282,994 A
• Filed: 04/16/1992
• Issued: 02/01/1994
• Est. Priority Date: 01/09/1990
• Status: Expired due to Term

• Current Assignee: University of Dayton
• Original Assignee: University of Dayton
• Inventors: Salyer, Ival O.
• Primary Examiner(s): Lieberman, Paul
• Assistant Examiner(s): OGDEN JR, NECHOLUS
• Application Number:
  US07/870,487
• Time in Patent Office: 656 Days
• Field of Search: 252/70, 165/10 A, 428/306, 428/403, 524/8
• US Class Current: 252/70
• CPC Class Codes: A01G 13/0237 Devices for protecting a specific part of a plant, e.g. roots, trunk or fruits
• CPC Class Codes: A41D 13/005 with controlled temperature
• CPC Class Codes: A47G 9/0215 with cooling or heating means electric blankets H05B3/34
• CPC Class Codes: A61F 2007/0238 in a pocket A61F2007/023 takes precedence
• CPC Class Codes: A61F 2007/0242 heated by microwaves
• CPC Class Codes: A61F 2007/0261 medicated
• CPC Class Codes: A61F 2007/0268 having a plurality of compartments being filled with a heat carrier heat packs stored in pockets A61F2007/023, A61F2007/0238
• CPC Class Codes: A61F 7/02 Compresses or poultices for effecting heating or cooling
• CPC Class Codes: A61L 24/02 containing inorganic materials
• CPC Class Codes: A61L 26/0004 containing inorganic materials
• CPC Class Codes: C08K 3/36 Silica
• CPC Class Codes: C08K 5/01 Hydrocarbons C08K5/0091 takes precedence
• CPC Class Codes: C08L 23/06 Polyethene
• CPC Class Codes: C08L 91/06 Waxes
• CPC Class Codes: C09K 5/063 Materials absorbing or liberating heat during crystallisation; Heat storage materials
• CPC Class Codes: F16D 2065/781 involving phase change of material
• CPC Class Codes: F16D 65/78 Features relating to cooling
• CPC Class Codes: F16D 66/00 Arrangements for monitoring working conditions, e.g. wear, temperature
• CPC Class Codes: F16D 69/02 Composition of linings ; Methods of manufacturing
• CPC Class Codes: F28D 20/02 using latent heat
• CPC Class Codes: F28D 20/023 : the latent heat storage material being enclosed in granular particles or dispersed in a porous, fibrous or cellular structure
• CPC Class Codes: H05K 5/0209 : Thermal insulation, e.g. for fire protection or for fire containment or for high temperature environments
• CPC Class Codes: H05K 5/0213 : Venting apertures; Constructional details thereof
• CPC Class Codes: Y02E 60/14 : Thermal energy storage
• CPC Class Codes: Y10T 428/2982 : Particulate matter [e.g., sphere, flake, etc.]
• CPC Class Codes: Y10T 428/2991 : Coated

Abstract

Free flowing, conformable powder-like mix of silica particles and a phase change material (PCM) is provided. The silica particles have a critical size of about 0.005 to about 0.025 microns and the PCM must be added to the silica in an amount of 75% or less PCM per combined weight of silica and PCM. The powder-like mix can be used in tableware items, medical wraps, tree wraps, garments, quilts and blankets, and in cementitious compositions of the type in which it is beneficial to use a PCM material. The silica-PCM mix can also be admixed with soil to provide a soil warming effect and placed about a tree, flower, or shrub.

Claims

1. A composition, comprising, in combination a phase change material and finely divided silica particles, said phase change material being selected from the group consisting of quaternary ammonium halide linear alkyl hydrocarbons, fatty acids, alcohols and esters, said silica particles having particle sizes of about 0.005 to about 0.025 microns, and said phase change material having a melting point and freezing point of from about -20°

to 140°

C., said phase change material being present in an amount of about 50-75% by weight and said silica particles being present in an amount of about 25-50% by weight based upon the weight of said composition, said composition being in the form of a freely flowing powder mix.

2. The composition of claim 1 wherein said silica particles have a surface area of between about 50 m² /g and about 500 m² /g.

3. The composition of claim 4 wherein said silica particles are precipitated silica particles.

4. The composition of claim 5 wherein said silica particles have been rendered less hydrophilic, partially hydrophobic or hydrophobic by surface treatment with 1-15 parts per hundred by weight of a silicone resin.

5. The composition of claim 1 further comprising a polar compound present in an amount of 5-25% by weight based on the total weight of said composition, and wherein said composition may be heated by microwave energy.

6. The composition of claim 5 wherein said phase change material is a linear alkyl hydrocarbon and said polar compound is glycerine.

7. A composition, comprising, in combination a water phase change material and finely divided precipitated silica particles which are hydrophilic or only slightly hydrophobic and which have particle sizes of about 0.005 to about 0.025 microns.

8. The composition of claim 7 wherein said water phase change material is present in an amount of about 50-75% by weight and said silica particles are present in an amount of 25-50% by weight based upon the weight of said composition, said composition being in the form of a freely flowing powder mix.

9. The composition of claim 8 wherein said water phase change material is present in an amount of 60-70% by weight of the composition.

10. The composition of claim 9 wherein the apparent density is about 0.5 gm/cc, and said silica particles have a surface area of between about 50 m² /g and about 500 m² /g.