Devices for maintaining food products at low temperature

Abstract

Disclosed is a thermal insulating device comprising: (a) a container or compartment for holding food and / or beverage in a cooled condition, said container comprising thermoformed liner having an average thickness of not greater than about 10 mm, said liner being formed at least in part from material selected from the group consisting of glass-clear polystyrene (GPPS), impact-modified polystyrene (HIPS), styrene-butadiene block copolymers, ASA, SAN, ABS, polyolefins, acrylates and methacrylates, polycarbonates (PCs), polyvinyl chloride (PVC), polyethylene terephthalate (PET) and mixtures, combinations, laminates and layers of these; and (b) thermal insulation adjacent said liner and comprising a polymeric material having closed cells therein wherein said cells are formed from and / or contain a blowing agent comprising at least about 50% by weight of transHFCO-1233zd.

Description

CROSS REFERENCE TO RELATED APPLICATIONS[0001]This application claims the priority benefit of U.S. Provisional Patent Application Ser. No. 61 / 788,293, filed Mar. 15, 2013, the contents of which are incorporated by reference herein in its entirety. This application is also a continuation-in-part of U.S. patent application Ser. No. 13 / 191,141 filed on Jul. 26, 2011 (now pending), which is based on and claims the priority benefit of U.S. Provisional Patent Application Ser. No. 61 / 368,249 filed Jul. 27, 2010, the contents of each of which are incorporated herein by reference in their entirety.FIELD OF THE INVENTION[0002]The present invention relates to devices, such as cold boxes, refrigerators, freezers and the like which are insulated and long-lasting.BACKGROUND OF THE INVENTION[0003]Typical refrigerator appliance cabinets consist of an outer metal cabinet, an inner plastic liner and an insulating foam core, typically polyurethane foam, in the space between the metal cabinet and the li...

AI Technical Summary

Benefits of technology

[0006]The present invention provides devices, such as cold boxes, refrigerators, freezers and the like which are insulated with foam and long-lasting. Preferably the device comprises: a cabinet or cabinet-like structure having an inner compartment for containing food, beverages and the like in a relatively cold condition; a liner which forms it at least a portion of the wall the inner compartment; and an insulating foam immediately adjacent to the liner or otherwise sufficiently adjacent to the liner such that the liner will be exposed to blowing agent degassing from the foam. Applicants have found that unexpected but highly desirable advantages can be achieved according to the preferred embodiments of the present invention wherein the foam is a closed cell foam, and more preferably a closed cell polyurethane foam, in which the blowing agent comprises in substantial part, and more preferably at least about 50% by weight, and even more preferably at least 75% by weight, of 1-chloro-3,3,3-trifluoropropene (1233zd). Applicants have found that foams blown with HFCO-1233zd, and preferably transHFCO-1233zd, provide a unique combination of highly desirable and beneficial blowing agent properties, such as low thermal conductivity, while at the same time being exceptionally benign with respect to the materials from which liners are made. As a result of this advantage, applicants have found that devices according to the present invention can be formed at relatively low cost but yet maintain high levels of reliability by forming the liners in relatively thin thicknesses. According to certain highly preferred embodiments, the liner is formed in part, and preferably in large part, from High Impact Polystyrene (HIPS), more preferably foodgrade HIPS, and even more preferably foodgrade HIPS, specially tailored for refrigeration products.

[0007]In addition, applicants have found that preferred embodiments of the present invention comprise a liner material, and in particular a preferred HIPS-based liner material, having an average thickness of not greater than about 5 mm, more preferably not greater than about 4 mm, and even more preferably in certain embodiments not greater than 3 mm. In certain highly preferred embodiments, the liner has an average thickness of not greater than about 2 mm, more preferably not greater than about 1.5 mm, more preferably not greater than about 1 mm, and even more preferably in certain embodiments not greater than 0.75 mm. In certain preferred embodiments, the liner has an average thickness of about 0.5 mm, which is generally considered to be the minimum thickness permitted according to certain commercial standards. While it is certainly possible to form liners having thicknesses greater than those indicated herein, and to thereby improve the reliability and longevity of the refrigerant cabinet by minimizing the impact of the chemical aggressiveness of the blowing agent, such a solution has significant and undesirable downsides in terms of the cost of the product as well as potentially creating difficulties in forming the product into the desired shape of the inner wall of the cabinet, which sometimes can have intricate corners and indentations. Accordingly, the present invention has the highly desirable yet unexpected advantage of providing a refrigerator cabinet which is at once low-cost, economical, thermally efficient, reliable and long-lasting.

[0008]Thus, according to certain preferred embodiments highly cost effective liners are used in the refrigerator which is insulated with a foam containing a highly thermally efficient halogenated olefin blowing agent, and in, particular HFCO-1233zd, while maintaining durability of the liner and avoidance of stress cracking or other deleterious effects.

[0010]It is an object of certain embodiments of the present invention to provide a refrigeration appliance liner to be fabricated from a thermoformable, plastic sheet material which retains a high level of toughness (impact properties) and strength (tensile properties), even at low temperatures (at 5° F. or less).

Problems solved by technology

Furthermore, applicants have come to appreciate that until a commercial refrigerator product has been manufactured under industrial conditions, and assessed for energy performance and ancillary performance in other aspects, for example, liner compatibility, adhesion to liner and metal cabinet and doors, freeze stability, and other quality aspects, the full value and performance of the system will not be fully understood.

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