Dry powder mixes comprising phase change materials

• US 5,211,949 A
• Filed: 02/18/1992
• Issued: 05/18/1993
• 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): Page, Thurman K.
• Assistant Examiner(s): BROUILLETTE, D GABRIELLE
• Application Number:
  US07/835,854
• Time in Patent Office: 455 Days
• Field of Search: 424/402, 424/443, 128/402, 128/403, 524/5, 524/8, 524/493, 428/402, 428/403, 252/69, 252/70, 602/2
• US Class Current: 424/402
• CPC Class Codes: A01G 13/0237 Devices for protecting a specific part of a plant, e.g. roots, trunk or fruits
• 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: 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: 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 (p.c.m.) is disclosed. The silica particles have a critical size of about 7×10^-3 to about 7×10^-2 microns and the pcm must be added to the silica in an amount of 80 wt. % 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 wrap useful as a hot or cold medical wrap or a tree wrap comprising an outer envelope formed from a liquid impervious polymer, and a powdered mix of a phase change material and finely divided silica particles, in combination, disposed within said outer envelope, said silica particles having particle sizes of about 7×

10^-3 to about 7×

10^-2 microns, said phase change material being selected from the group consisting of water, glycerine, ethylene glycol, crystalline alkyl hydrocarbons having a carbon chain length of C₁₄ and greater, crystalline fatty acids, crystalline fatty acid esters, crystalline alicyclic hydrocarbons, crystalline aromatic compounds, hydrated salts, clathrates, semi-clathrates, gas clathrates, polyethylene glycol, and halogen-terminated alkyl hydrocarbons, said phase change material having a melting and freezing point of from about -20°

to about 140°

C. and being present in an amount of 80% or less by weight and said silica particles being present in an amount of 20% or more by weight based on the total weight of the combination of phase change material and silica particles.

2. A wrap as recited in claim 1 wherein said silica particles have a surface area of between about 50 m² /g to about 500 m² /g.

3. A wrap as recited in claim 1 wherein said silica particles are selected from the group consisting of fumed and precipitated silicas.

4. A wrap as recited in claim 1 wherein said silica particles are hydrophilic precipitated silica particles or hydrophobic silica particles.

5. A wrap as recited in claim 1 wherein said phase change material is present in an amount of 50-80 wt. %.

6. A wrap as recited in claim 1 further comprising a polar compound present in an amount of 5-25 wt. % based on the total weight of said silica, phase change material and polar compound, and wherein said wrap may be heated by microwave energy.

7. A wrap as recited in claim 1 wherein said phase change material comprises a polar phase change material and wherein said wrap may be heated by microwave energy.

8. A wrap as recited in claim 7 wherein said polar phase change material is chosen from the group consisting of water, glycerine, ethylene glycol, polyethylene glycol, clathrates, semi-clathrates, gas clathrates and hydrated salts.

9. A wrap as recited in claim 1 wherein said phase change material comprises a crystalline alkyl hydrocarbon having a carbon chain length of C₁₄ and greater.

10. A wrap as recited in claim 1 wherein said envelope comprises a polymeric compound selected from the group consisting of polyesters, butadieneacrylonitrile copolymers, vinyl polymers, polyethylene, and ethylene-vinyl acetate copolymers.

11. A wrap as recited in claim 1 further including a layer of thermal insulation surrounding said outer envelope.