INSULATED HEAT SENSITIVE COMPONENT

Abstract: An insulated heat sensitive component and an engine compartment comprising: A) a heat sensitive component; and B) a corestock of one or more porous or open-celled rigid material matrixes which has been evacuated to an absolute pressure of about 10 torr or less and sealed, and which covers about 20 percent or more of the surface area of the component; optionally, wherein the corestock is situated within an evacuated cavity of the component; or C) an evacuated panel comprising a deformable receptacle which has been evacuated to an absolute pressure of about 10 torr or less and sealed surrounding a corestock of one or more porous or open-celled rigid material matrixes, and which covers about 20 percent or more of the surface area of the component, where the corestock or the evacuated panel provides and R value of 10 per inch or greater.

Description: INSULATED HEAT SENSITIVE COMPONENT Field of the Invention This invention relates to an insulated heat sensitive component and to an engine compartment containing an insulated heat sensitive component. Background of the Invention The engine compartments of vehicles such as automobiles generate considerable amounts of heat when operating and cooling down. Sources of heat include internal combustion or diesel engines, exhaust manifolds, and catalytic converters. Certain automotive components are very heat sensitive. Typical heat-sensitive components include batteries, power distribution centers, relay enclosures, fuse boxes, computers and communications devices. Batteries provide electricity or electrical power for starting automobiles while power distribution centers distribute electrical power from the batteries and/or the alternators to other electrical components such as spark and/or glow plugs, radio or entertainment center, lights, heater, antennas, air conditioner, instrument panel, locks, windows, and the like. Conventional lead-acid batteries rapidly deteriorate in electrical charge performance when electrolyte temperatures within them exceed about 60°C. Reaction rate chemistry between lead and acid doubles for approximately each 10°C increment over about 60°C. The resulting lead salts collect as debris in the bottom of battery cells and bridge plates causing an electrical short in the battery. Prolonged and/or repeated exposure to such temperature levels may cause such batteries to prematurely lose their ability to generate electrical charge. Premature battery failure has resulted in high warranty costs for automobile manufacturers. The problem of excessive heat exposure has been exacerbated by modern vehicle styling, lower hood lines for aerodynamics, and more-enclosed architecture in the engine compartment. All have resulted in dense packing of automotive components, reduced engine compartment space, and reduced grille opening space. The dense packing has increased temperatures in the engine compartments, commonly exceeding 150°C around the engines and exhaust manifolds. The dense packing and reduced grille space have also reduced cooling air flow and venting within engine compartments. Excessive temperatures may occur during operation of the automobile, during idling, or during cool down. The highest temperatures are most commonly observed during cooling down since the engine is still emanating heat and the engine compartment is usually not being cooled by fan or vent air. During cool down, battery electrolyte temperatures of 70°C or more and 90°C or more are commonly encountered, particularly in warm or hot climates. Attempts to address the problem of excessive heat exposure to batteries have been unsuccessful. Technologies employed have included use of additional ducting or additional fans to direct vent air on the batteries, relocating the batteries to a separate compartment or outside the engine compartment, insulating the batteries with plastic molding or cross-linked closed cell polyvinyl chloride foams. Use of additional ducting or fans is costly, space-consuming, and ineffective during cooling down. Relocation of batteries is costly and creates safety issues. Use of plastic molding as a shield is marginally effective and consumes too much space. Use of polyvinyl chloride foams, referred to as "huggies" in the industry, typically lower battery electrolyte temperatures about 10°C or less, and only partially address the problem. It would be desirable to have a means for insulating heat sensitive components of vehicles to better protect them from elevated engine compartment temperatures. Such means would displace as little volume or space as possible within the engine compartment. Summary of the Invention This invention relates to an engine compartment comprising: A) a heat sensitive component; and B) a corestock of one or more porous or open-celled rigid material matrixes which has been evacuated to an absolute pressure of about 10 torr or less and sealed, and which covers about 20 percent or more of the surface area of the component; optionally, wherein the corestock is situated within an evacuated cavity of the component; or C) an evacuated panel comprising a deformable receptacle which has been evacuated to an absolute pressure of about 10 torr or less and sealed surrounding a corestock of one or more porous or open-celled rigid material matrixes, and which covers about 20 percent or more of the surface area of the component, where the corestock or the evacuated panel provides an R value of 10 per inch or greater. This invention also relates to an insulated heat sensitive component comprising: A) a heat sensitive component; and B) a corestock of one or more porous or open-celled rigid material matrixes which has been evacuated to an absolute pressure of about 10 torr or less and sealed, and which covers about 20 percent or more of the surface area of the component; optionally, wherein the corestock is situated within an evacuated cavity of the component; or C) an evacuated panel comprising a deformable receptacle which has been evacuated to an absolute pressure of about 10 torr or less and sealed surrounding a corestock of one or more porous or open-celled rigid material matrixes, and which covers about 20 percent or more of the surface area of the component, where the corestock or the evacuated panel provides an R value of 10 per inch or greater. The insulated heat sensitive component may be a small or miniaturized component used as part of a larger assembly, such as a vehicle, for example, as part of an engine compartment. While insulation of the heat sensitive component from excessive heat infiltration from an environment of higher heat is a primary use of this invention, another useful aspect of this invention is for the retention of heat, or for the stabilization of the environment of a component with regard to either heat loss or gain. A wide variety of heat sensitive components may be protected by means of this invention, for example, insulated automotive components such as an insulated battery, power distribution center, fuse panel, relay enclosure, computer or communication device. Components of particular interest include a battery, a computer and a communications device. A particularly useful embodiment is an insulated automotive battery, especially where the component is a lead acid battery and the engine compartment is an automobile engine compartment. The battery may have an evacuated insulation panel inside or outside of the battery or a foam situated within an evacuated cavity within the battery. In one or more aspects of this invention, the use of an evacuated panel, also known as an evacuated insulation panel or a vacuum insulation panel (VIP), to retard heat flow is preferred. Brief Description of the Figures Figure 1 is a plan view of an engine compartment containing an insulated battery of the present invention. Figure 2 is a plan view of an engine compartment containing two insulated batteries of the present invention. Figure 3 is a perspective view of an embodiment of an insulated battery of the present invention. Figure 4 is a perspective view of another embodiment insulated battery of the present invention. Figure 5 is a graph showing the time versus temperature performance for an insulated battery of the present invention in an engine compartment of an automobile. The figure represents test results obtained using the insulated battery of Example 1. Figure 6 is a graph showing the time versus temperature performance for an insulated battery of the present invention in an engine compartment of a diesel truck. The figure represents test results obtained using the insulated batteries of Example 2. Figure 7 is a graph showing the time versus temperature performance for an insulated battery of the present invention in an engine compartment of a gasoline- powered truck. The figure represents test results obtained using the insulated battery of Example 3. Detailed Description of the Invention The present invention addresses the problem of maintaining a stable environment for heat sensitive components, especially components of vehicles where considerations of weight and size are critical, and where the environment, such as, for example, in an engine compartment may be quite harsh and continuously in flux during operation of the vehicle. In one embodiment of this invention, the corestock of one or more porous or open-celled rigid material matrixes has one or more indentations therein which extend in at least one dimension across a surface of a rigid material matrix, and wherein the receptacle, or an exterior surface of an evacuated cavity of the component, substantially conforms to the shape of the corestock and the indentations therein and the finished panel has surfaces which are substantially non-wrinkled; optionally, further comprising one or more rigid plates having one or more indentations therein, the one or more plates being situated contiguous to a major surface of the corestock Suitable materials for the rigid material matrix of the corestock is an open cell thermoplastic foam, a polycarbonate foam, a thermoset foam, a polyurethane foam, an epoxy-resin foam, a formaldehyde foam, a phenolic foam, an Isocyanurate foam, silica, fiberglass, glass bead, aerogel, or xerogel. Preferred matrix materials include an alkenyl aromatic polymer foam having an average cell size of less than about 70 micrometers, a propylene polymer foam, an extruded foam of coalesced strand configuration, an open channel foam or a perforated foam. An alternative embodiment for this aspect of the invention, which is the subject matter of U.S. Serial No. 08/993,536 filed on December 18, 1997, allowed, and a related PCT case filed September 16, 1998, both of which are hereby incorporated by reference, addresses the problem of wrinkling of a surface or surfaces of an evacuated insulation panel having a corestock therein of a porous or open-celled rigid material matrix, such as an open-cell, alkenyl aromatic polymer foam, by providing a corestock having indentations therein. When the corestock shrinks upon evacuation and/or exposure to elevated temperatures, the deformable receptacle or enclosure surrounding the corestock deforms to the shrunken corestock. The indentations provide extra surface area for the receptacle to deform or conform within. Without the indentations, wrinkles would form in the receptacle upon shrinkage of the corestock. The invention significantly improves the aesthetics and physical appearance of the panel. An additional benefit is reduced evacuation time. Preferably one or both of the one or more porous or open-celled rigid material matrixes and the one or more plates have a plurality of indentations. The indentations necessarily extend in at least one dimension across the surface of a material matrix, but preferably the indentations extend in two dimensions across the surface of one or both of the one or more porous or open-celled rigid material matrixes and the one or more plates. In one embodiment, the matrix has indentations therein in a criss-crossing rectangular or diagonal pattern across substantially the entire surface of one or both of the one or more porous or open -celled rigid material matrixes and the one or more plates. In another embodiment, the matrix has indentations therein in a dimple pattern across substantially the entire surface of one or both of the one or more porous or open- celled rigid material matrixes and the one or more plates. Although generally the indentations are about 3.2 millimeters or less in depth and about 3.2 millimeters or less across, they may also be larger for particular corestocks. Indentations in a surface or surfaces of the matrix may take a variety of forms such as dimples, grooves, or troughs. The indentations may take a regular or irregular pattern across a surface. Indentations may traverse or extend across the surface continuously or non-continuously. The indentations extend in two dimensions across a surface or surfaces of the matrix. The indentations preferably extend generally from one edge of the matrix to another. If the indentations are in the form of dimples, they preferably occur at regular intervals across substantially an entire surface or surfaces of the matrix. If the indentations are in the form of grooves or troughs, they preferably criss-cross as they traverse or extend across the surface. Preferably, indentations are provided at an incidence and at a depth such that the deformable receptacle will rest upon the surfaces of the matrix and the indentations within upon shrinkage of the corestock and that the surfaces of the receptacle are substantially free of wrinkles. In other words, the additional corestock surface area provided by the indentations after shrinkage of the corestock preferably approximately corresponds to the total surface area of the corestock anticipated to be lost due to shrinkage. Indentations may be to any depth or width within the corestock but preferably have a depth of about 1/8 inch (3.2 millimeters) or less and a width of about 1/8 inch (3.2 millimeters) or less. Indentations may be impressed into the corestock by any means known in the art such as the following: a) passing the foam through a set of opposing impressing rollers having the desired groove pattern as raised ridges in the rollers; b) impressing with opposing plates having the desired groove pattern as raised ridges in the plates; c) impressing the desired pattern with a series of wires positioned adjacent the corestock; d) cutting the desired pattern into the corestock using knives, saws, routers, or water spray; and e) melting the desired pattern into the corestock with hot wires or other heat source. In the case of a) and b), momentary impression by the raised ridges is usually sufficient to leave permanent indentations, although impression for longer periods of time may be desirable if the corestock is being compressed for other reasons. This invention may be useful for the manufacture of any vacuum insulation panel which utilizes a corestock which exhibits contraction upon exposure to atmospheric pressure or elevated temperatures while encapsulated within a barrier pouch or receptacle. Examples of suitable corestock materials for use in this invention are polystyrene foam; other open cell thermoplastic foam such as polypropylene, preferably the polypropylene foam described in U.S. patent 5,527,573, which is hereby incorporated by reference; polycarbonate foams; thermoset foams, such as polyurethane foam, epoxy-resin foams, formaldehyde foams, phenolic foams, Isocyanurate foams; or any other polymeric material, either thermoplastic or thermoset, which has an open cell structure allowing removal of air and gas from the cells before encapsulation. Other materials generally useful as corestock materials in the manufacture of vacuum insulation panels which may benefit from the application of this invention are silica or other powder filled panels if the loose powder is sufficiently compressed or bonded in any way to form a unified structure, which is then scored to produce a smooth surface after evacuation. Additionally, this invention can be applied to compressed fiberglass or glass bead panels, if the core is sufficiently solid to allow scoring of the surface, and to aerogel and xerogel filler materials, which exhibit shrinkage upon encapsulation in VIP's. Preferred corestock materials are polystyrene and polypropylene foams, with polystyrene foams being especially preferred. It is contemplated that the present invention could be practiced by placing one or more rigid plates having indentations therein at one or more surfaces of a foam within an evacuated insulation panel. The indentations could take the form, pattern, and dimensions as described above for indentations within the foam. The panel could be assembled as described above except that one or more plates are inserted within the deformable receptacle along with the foam. For a typical rectangular or square panel, plates will typically be situated at the two major surfaces of the foam. The plate or plates can be made of any natural or synthetic material, such as for example, metals, wood, plastic, which is chemically inert to the corestock and the receptacle, as long as it has sufficient rigidity to resist deformation during evacuation. Upon evacuation of the panel and shrinkage of the foam, the deformable receptacle will conform to the shape of the foam and rest substantially within the indentations of the plate or plates. The use of plates inside a VIP, or outside a VIP, shields low melting point corestocks from transient heat exposure, such as is experienced during the foaming of polyurethane foam around a VIP during the construction of an appliance. The present invention addresses the problem of insulating or shielding an automotive component such as a battery by placing evacuated open-cell foams adjacent the exterior of the component or battery. The evacuated open-cell foams provide sufficient insulating capability while displacing minimal volume. In a preferred embodiment wherein the corestock is a foam, typical foams, when evacuated, provide an "R-value" or heat resistance on a per inch thickness basis of about 10 or more, preferably about 15 or more, and most preferably about 20 or more. "R-value" is the reciprocal of foam thermal conductivity as measured in units of BTU in./hr. ft2.°F. For instance, an evacuated foam having a thermal conductivity of 0.1 BTU in./hr. ft 2 .°F (0.0144 Watts/meter K) has an R-value of 10. The above R-values are initial R-values rather than aged R-values. A conventional automobile battery takes the form of a rectangular or square- shaped box or case with protruding positive and negative electrodes; the conventional battery has a top panel, a bottom panel, and four side panels. The exposed surface area of the conventional battery takes the form of these panels. In the present invention, the evacuated foams preferably cover about 20 percent or more and most preferably about 50 percent or more of the exterior surface area of the automobile battery. The extent of coverage of the exterior surfaces will vary considerably depending upon the anticipated maximum temperature to which the battery will be exposed and how much insulation protection is desired. The foams may take the form of evacuated insulation panels which can be placed adjacent to or in proximity to the exterior surfaces. The panels can be placed inside or outside of the battery. Alternately, such panels can be formed or fashioned into an insulating box or blanket into which the battery can be placed or encased. Optionally, the panels may be protected by covering them with cushion material or rigid facers to protect the physical integrity of the panel and its hermetic seal. Alternately, foams can be positioned within evacuated cavities inside the battery to form the equivalent of an evacuated panel or panels within the battery. Instead of being situated at all or most exterior surfaces of the battery, the panels may be placed in proximity or adjacent to only those exterior surfaces directly exposed to radiant heat generated within the engine compartment. The exterior surfaces of the battery not directly exposed to radiant heat may be covered with panels or be left uncovered. Optionally, some exterior surface area may be left uncovered to permit dissipation of heat generated within the battery or heat absorbed by the battery during operation of the automobile. The battery may be of any type known in the art to be sensitive to operating temperature extremes. Useful batteries include but are not limited to those of lead/acid and lithium metal halide chemistries. Engine compartments having insulated batteries therein are seen in Figures 1 and 2. In Figure 1, an engine compartment 10 comprises a battery 14 and an engine 18. In Figure 2, an engine compartment 20 comprises insulated batteries 22 and 24 and an engine 28. Embodiments of the insulated battery are seen in Figures 3 and 4. In Figure 3, an insulated battery 30 comprises a front face 36, a top face 38, a back face 40, a bottom face 42, and side faces 44 and 46. Positive and negative electrodes 32 and 34 protrude from front face 36. Evacuated panels 48 are positioned adjacent faces 36, 40, 44, and 46 to snugly or tightly cover some portion of or their entire exposed surfaces. The panels 48 which cover faces 40, 44, and 46 are connected together at panel interfaces 47 to form a foldable pouch 49 having multiple interconnected but discrete evacuated foams. In Figure 4, an insulated battery 50 comprises a front face 52, a top face 54, a back face 56, a bottom face 52, and side faces 58 and 60. Positive and negative electrodes 62 and 64 protrude from front face 52. Evacuated panels 66 are positioned adjacent faces 52, 58, and 60 to snugly or tightly cover some portion of or their entire exposed surfaces. The foam has an open cell content of about 50 percent or more, preferably about 70, more preferably about 90 percent or more, and most preferably about 95 percent or more according to ASTM 2856-A. The foam may be of any cell size, but microcellular cell sizes are preferred for their superior insulating performance. Cell sizes or pore sizes are measured according to ASTM D3576-77 except that measurement is taken from an enlarged photograph obtained by scanning electron microscopy instead of measurement taken directly from the foam. Microcellular foams have an average cell size of about 70 microns or less, preferably about 5 to about 30 micrometers, more preferably about 1 to about 30 micrometers. The foams preferably have the density of from about 16 to about 250 and most preferably from about 25 to about 100 kilograms per cubic meter according to ASTM D- 1622-88. An evacuated foam is a foam having within its cells a partial vacuum or near total vacuum of subatmospheric absolute pressure. An evacuated foam preferably has an absolute pressure of about 10 torr or less, more preferably about 1 torr or less, and most preferably about 0.1 torr or less. The receptacle or enclosure of the evacuated panel may be formed of any of those known in the art. One embodiment of an evacuated panel employs a receptacle or enclosure formed of a laminate sheet of three or more layers. The outer layer comprises a scratch resistant material such as a polyester or a nylon. An interior layer or layers comprise a barrier material such as aluminum, polyvinylidine chloride, or polyvinyl alcohol. The barrier material may be in the form of a separately applied foil or film or, in the case of a metal, may be applied by vapor deposition. The inner layer comprises a heat sealable material such as polyethylene or ethylene/acrylic acid copolymer. Additional teachings are seen in U.S. Patent No. 5,346,928 and 5,627,219, which is hereby incorporated herein by reference. An infrared attenuating agent (IAA) is preferably incorporated into the foam. It may be an infrared reflecting or absorbing substance or both. The IAA is composed of a different substance than the substrate of the foam in which it is hereby incorporated. Useful IAA include particulate flakes of metals such as aluminum, silver, and gold and carbonaceous substances such as carbon black, activated carbon black, and graphite. Useful carbon blacks include thermal black, furnace black, acetylene black, and channel black. Useful graphites are natural graphite and synthetic graphite. Preferred IAA are carbon black and graphite. The IAA preferably comprises between about 1.0 and about 20 weight percent, more preferably about 4.0 to about 20 weight percent, and most preferably between about 4.0 and about 10.0 weight percent based upon the weight of the polymer material. Substantial infrared attenuation activity occurs between about 4 percent and about 40 percent based upon the weight of the polymer material. In the case of carbon black and graphite, it is desirable to use particles of a size which achieve a high degree of dispersion in the foam. The foam may be compressed to about 40 to about 90 percent of its initial thickness or volume to enhance heat insulating capability or a per unit thickness basis. Compressed foams are taught in WO 97/27986, which is hereby incorporated herein by reference. The present foams can be comprised of any known organic or inorganic substance known to be useful in making an open cell foam. Useful substances include thermoplastic polymers, thermoset polymers, aerogels, ceramics, and glass. Useful thermoplastic polymers include ethylene polymers and alkenyl aromatic polymers. Useful ethylene polymers include polyethylenes such as low density polyethylene. Useful thermoset polymers include polyisocyanurates, polyurethanes and phenolics. A useful foam comprises an alkenyl aromatic polymer material. Suitable alkenyl aromatic polymer materials include alkenyl aromatic homopolymers and copolymers of alkenyl aromatic compounds and copolymerizable ethylenically unsaturated comonomers. The alkenyl aromatic polymer material may further include minor proportions of non-alkenyl aromatic polymers. The alkenyl aromatic polymer material may be comprised solely of one or more alkenyl aromatic homopolymers, one or more alkenyl aromatic copolymers, a blend of one or more of each of alkenyl aromatic homopolymers and copolymers, or blends of any of the foregoing with a non- alkenyl aromatic polymer. Regardless of composition, the alkenyl aromatic polymer material comprises greater than 50 and preferably greater than 70 weight percent alkenyl aromatic monomeric units. Most preferably, the alkenyl aromatic polymer material is comprised entirely of alkenyl aromatic monomeric units. Suitable alkenyl aromatic polymers include those derived from alkenyl aromatic compounds such as styrene, alphamethylstyrene, ethylstyrene, vinyl benzene, vinyl toluene, chlorostyrene, and bromostyrene. A preferred alkenyl aromatic polymer is polystyrene. Minor amounts of monoethylenically unsaturated compounds such as C 2-6 alkyl acids and esters, ionomeric derivatives, and C 4 _ 6 dienes may be copolymerized with alkenyl aromatic compounds. Examples of copolymerizable compounds include acrylic acid, methacrylic acid, ethacrylic acid, maleic acid, itaconic acid, acrylonitrile, maleic anhydride, methyl acrylate, ethyl acrylate, isobutyl acrylate, n-butyl acrylate, methyl methacrylate, vinyl acetate and butadiene. Preferred foams comprise substantially (i.e., greater than 70 percent by weight) and most preferably entirely of polystyrene. Preferably, the alkenyl aromatic polymer foam is free of rubber content such as C 4-6 dienes and thermoset polymer content such as polyisocyanurate or polyurethane. A useful microcellular foam is an extruded, open-cell alkenyl aromatic polymer foam. The open-cell foam comprises an alkenyl aromatic polymer material comprising greater than 50 weight percent of alkenyl aromatic monomeric units and preferably about 70 percent or more alkenyl aromatic monomeric units. The foam may be comprised entirely of polystyrene. The foam has an open cell content of about 50 percent or more, preferably about 90 percent or more, and most preferably about 95 percent or more open cell according to ASTM 2856-A. The foam has an average cell size of about 70 micrometers or less, preferably from about 1 to about 30 micrometers, and most preferably about 5 to about 30 micrometers according to ASTM D3576-77 except that measurement is taken by scanning electron microscopy instead of directly from the foam. The foam is particularly useful in vacuum insulation panels. Description of its methods of manufacture are seen below and in WO 96/34038, which is hereby incorporated herein by reference. The extruded, open-cell microcellular foam may be prepared by heating a thermoplastic material to form a plasticized or melt polymer material, incoφorating therein a blowing agent to form a foamable gel, and extruding the gel through a die to form the foam product. Prior to mixing with the blowing agent, the polymer material is heated to a temperature at or above its glass transition temperature or melting point. The blowing agent may be incoφorated or mixed into the melt polymer material by any means known in the art such as with an extruder, mixer, blender, or the like. The blowing agent is mixed with the melt polymer material at an elevated pressure sufficient to prevent substantial expansion of the melt polymer material and to generally disperse the blowing agent homogeneously therein. The amount of blowing agent incoφorated is about 0.06 to 0.17 gram-moles per 100 grams of polymer. A nucleating agent such as talc is blended in the polymer melt or dry blended with the polymer material prior to plasticizing or melting. The foamable gel is typically cooled to a lower foaming temperature to optimize desired physical characteristics of the foam. The gel may be cooled in the extruder or other mixing device or in separate coolers. The foaming temperature must be high enough to allow formation of the open-cell structure but low enough to prevent foam collapse upon extrusion. Desirable foaming temperatures range from about 105°C to about 160°C and preferably from about 120°C to about 135°C. The gel is then extruded or conveyed through a die of desired shape to a zone of reduced or lower pressure to form the foam. The zone of lower pressure is at a pressure lower than that in which the foamable gel is maintained prior to extrusion through the die. The lower pressure may be superatmospheric or subatmospheric (evacuated or vacuum), but is preferably at an atmospheric level. Open cell polyurethane and polyisocyanurate foams can be made by reacting two preformulated components, commonly called the A-component and the B- component. The blowing agent may be dispersed in either the isocyanate or the polyol or both. Suitable polyisocyanates include diisocyanates such as m-phenylene diisocyanate, toluene-2,4-diisocyanate, toluene-2,6-diisocyanate, mixtures of 2,4- and 2,6-toluene diisocyanate, hexamethylene-l,6-diisocyanate, tetramethylene-1,4- diisocyanate, cyclohexane-l,4-diisocyanate, hexahydrotoluene 2,4- and 2,6- diisocyanate, naphthalene- 1 ,5-diisocyanate, diphenyl methane-4 ,4' -diisocyanate, 4,4'- diphenylenediisocyanate, 3,3'-dimethoxy-4,4'-biphenyldiisocyanate, 3,3'-dimethyl- 4,4'-biphenyldiisocyanate, and 3,3'-dimethyldiphenylmethane-4,4'-diisocyanate; the triisocyanates such as 4,4',4"-triphenylmethane-triisocyanate, polymethylenepolyphenyl isocyanate, toluene-2,4,6-triisocyanate; and the tetraisocyanates such as 4,4'- dimethyldiphenylmethane-2,2',5,5'-tetraisocyanate. Suitable polyols include: ethylene glycol; propylene glycol-(l,2) and -(1,3); butylene glycol-(l,4) and -(2,3); hexane diol-(l,6); octane diol-(l,8); neopentyl glycol; 1,4-bishydroxymethyl cyclohexane; 2-methyl-l,3-propane diol; glycerin; trimethylolpropane; trimethylolethane; hexane triol-( 1,2,6); butane triol-( 1,2,4); pentaerythritol; quinitol; mannitol; sorbitol; formitol; a-methyl-glucoside; diethylene glycol; triethylene glycol; tetraethylene glycol and higher polyethylene glycols; dipropylene glycol and higher polypropylene glycols as well as dibutylene glycol and higher polybutylene glycols. Suitable polyols further include oxyalkylene glycols, such as diethylene glycol, dipropylene glycol, triethylene glycol, tripropylene glycol, tetraethylene glycol, tetrapropylene glycol, trimethylene glycol and tetramethylene glycol. Polyurethane foams can be prepared by reacting the polyol and the isocyanate on a 0.7: 1 to 1.1:1 equivalent basis. The polyisocyanurate foams of the invention are advantageously prepared by reacting the polyisocyanate with a minor amount of polyol to provide about 0.10 to 0.70 hydroxyl equivalents of polyol per equivalent of polyisocyanate. Useful polyurethane and polyisocyanurate foams and processes for making them are seen in U.S. Patent Nos. 3,580,869; 4,795,763; 5,260,344; 5,288,766; 5,334,624; and 5,346,928, which are incoφorated herein by reference. Aerogels may be comprised of a variety of materials such as silica, metal oxides, carbon, and formaldehyde derivatives. Teachings to aerogels and methods of making are found in U.S. Patent Nos. 5,081,163; 5,242,647; 5,275,796; 5,358,802; 5,381,149; and 5,395,805, which are incoφorated herein by reference. Microcellular thermoplastic foams may be lightly cross-linked or non- crosslinked. The term "non-crosslinked" means the foam is substantially free of crosslinking. The term is inclusive however, of the slight degree of crosslinking which may occur naturally without the use of crosslinking agents or radiation. Non- crosslinked foams contain no more than 5 percent gel per ASTM D-2765-84 Method A. Useful foams include open-cell propylene polymer foams such as those taught in U.S. Patent Nos. 5,348,795 and 5,567,742, which are incoφorated herein by reference. Useful propylene polymer foams include extruded coalesced strand foams, particularly those of about 50 percent or more, preferably about 80 percent, and most preferably about 95 or more open cell content. Extruded coalesced strand foams are particularly useful because they can be evacuated more quickly than foams extruded from a conventional slit die or otherwise of a conventional unitary structure. Extruded coalesced strand foams define continuous channels between the strands extending the extrusion direction of the foam. The coalesced strands foam may be described as open channel or closed channel depending upon how closely packed the coalesced strands are. Open channel foams are those wherein a large proportion of the strand-to-strand interfaces define continuous channels which, on end or in cross-section, are visibly open to the unaided eye. Closed channel foams are those wherein a large proportion of the strand-to-strand interfaces define continuous channels which, on end or in cross-section, are visibly closed to the unaided eye. Closed channel foams exhibit faster evacuation times than foams of conventional unitary structure. Open channel foams exhibit faster evacuation times than foams of conventional unitary structure and closed channel foams. Evacuated insulation panels containing coalesced strand foams of either open channel and closed channel configuration are within the scope of the present invention. Strand foam structures are described in U.S. Patent Nos. 4,824,720 and 5,124,097, which are incoφorated herein by reference. Preferably, the primary source of evacuation or suction takes place directional with the continuous channels (extrusion direction) but may occur from any direction such as generally peφendicular to the direction of the continuous channels. Although use of a coalesced strand foam structure is preferred when continuous channels are desired, it is also within the scope of the present invention to introduce a plurality or multiplicity of channels into a foam of conventional unitary structure by perforating it partly through or entirely through with nails or needles or the like. Perforation of foam is taught in U.S. Patent No. 5,585,058, which is hereby incoφorated herein by reference. Evacuated panels may be formed as follows: a) the foam is placed inside a receptacle or enclosure such as a bag capable of being made air tight or hermetically sealed; b) the interior of the receptacle or enclosure and the foam are evacuated to a partial or near total vacuum; and c) the receptacle or enclosure is sealed to be air tight or hermetically sealed. The interior of the evacuated or vacuum panel is evacuated to about 10 torr or less, more preferably to about 1 torr or less, and most preferably to about 0.1 torr or less absolute pressure. Prior to incoφoration in an evacuated panel, certain foams may be compressed to increase insulating capability on a per unit thickness or volume basis and/or may be simultaneously compressed and heated to enhance the dimensional stability. To increase insulating capability on a per unit thickness basis, alkenyl aromatic polymer foams and polyurethane/polyisocyanurate foams may be compressed within about 30 to about 70 percent of their original thickness. To enhance dimensional stability, alkenyl aromatic polymer foams may be simultaneously heated and compressed to within 90-95 percent of initial thickness and preferably to a lower percentage of initial thickness. Teachings to compression and simultaneous compression and heating are seen in WO 97/27986 and Attorney's Docket No. 43401, filed July 14, 1997, which are incoφorated herein by reference. The skin layer of the foam may also be skived off or planed off to better expose the open cell structure of the foam. The foam may be evacuated by any means known in the art for withdrawing gases such as with a suction nozzle or by placement in an evacuating chamber. The receptacle or enclosure of the evacuated panel may be formed of any of those know in the art. One embodiment of an evacuated panel employs a receptacle or enclosure formed of a laminate sheet of three or more layers. The outer layer comprises a scratch resistant material such as a polyester. The middle layer comprises a barrier material such as aluminum, polyvinylidine chloride, or polyvinyl alcohol. To further enhance the long-term performance of the vacuum panel, the evacuated interior of the panel may be provided with a "getter" material. The getter material adsorbs gases and/or vapors which seep or permeate into the vacuum panel over time. Conventional getter materials include metal and metal alloys of barium, aluminum, magnesium, calcium, iron, nickel, and vanadium. Teachings to suitable getter materials include but are not limited to those set forth in U.S. Patent Nos. 5,191,980; 5,312,606; 5,312,607; and WO 93/25843, which are incoφorated herein by reference. Other types of useful getter materials include conventional desiccants, which are useful for absorbing water vapor or moisture. Such materials are advantageously incoφorated into the evacuated insulation panel in the form of a packet having a porous or permeable wrapper or receptacle containing the material therein. Useful materials include silica gel, activated alumina, activated carbon, aluminum-rich zeolites, calcium chloride, calcium oxide, and calcium sulfate. A preferred material is calcium oxide. The term "automobile" as used herein includes any motor vehicle such as a car, truck, van, bus, tractor, construction vehicle and others which use conventional small automotive type batteries, or more recent developments including larger electrical arrays, such as, for example, electric cars, and fuel cells. The term "vehicle" as used herein, unless otherwise stated, embraces all manner of devices of conveyance including automobiles, boats, ships, aiφlanes, rockets and spacecraft. As used herein, the term "engine compartment" can be that of any vehicle, while an insulated heat sensitive component can be located anywhere on, in or near a vehicle. Prior provisional applications U.S. Serial Nos. 60/061,963, filed October 14, 1997, and 60/068,032, filed December 18, 1997, are incoφorated herein by reference. The present invention may be extended to insulate any vehicle component which is sensitive to heat. The component can be any functional device or apparatus which contributes to the operation or utility of the vehicle. EXAMPLES Example 1 An insulated battery of the present invention was prepared and placed in an engine compartment of an automobile to test its effectiveness in maintaining temperature control within the battery. A Group 75 automobile battery was covered snugly by evacuated insulation panels on its front face (electrode face) and two side faces. A representation of the insulated battery is seen in Figure 3. The evacuated panels contained an extruded open cell propylene polymer foam having an 80 percent open cell content. The open cells of the foam were evacuated to an absolute pressure of about 0.1 torr, and the foam was hermetically sealed in a gas-impermeable laminate bag. The foam and panel were 0.27 inch (0.68 centimeters) thick. The panel exhibited an R-value of 14.4 per inch. The insulated battery was placed in the front of the engine compartment facing the engine on the passenger side as seen in Figure 1. The automobile, a Pontiac Grand Prix, was subjected to the R- 15-61 driving cycle. In that cycle, the automobile is subjected to the following in sequence: driving three laps of a test track at 60 miles per hour (mph); driving on a rural highway for 0.4 hour; driving in city traffic for 0.9 hour; allowing the automobile to idle for 0.4 hour; turning engine off for 0.3 hour for a cool down period; grade/towing (3.7 laps at 30 mph) for 0.8 hour; and driving at high speed for two laps of the test track for 0.8 hour. The cycle is conducted at an average ambient temperature of 95 F. Total testing time is 4.6 hours. The temperature performance of the insulated battery was measured by comparing the temperature of the exterior surface of the evacuated foam at the front side with that of the exterior surface of the battery case contiguous to the evacuated panel on the front side. In testing insulated batteries, it was found that the temperature of the exterior surface of the battery case corresponded closely to that of the temperature of the electrolyte inside the battery. The insulated battery provided excellent control of electrolyte temperatures as seen in Figure 5. The two temperatures recorded did not equalize until four hours had elapsed. Further, approximately 3 hours elapsed before electrolyte temperatures reached the critical 60°C ( 140°F) temperature. Example 2 An insulated battery of the present invention was prepared and placed in an engine compartment of diesel truck to test its effectiveness in maintaining temperature control within the battery. The battery was one of two insulated batteries placed in the engine compartment. A Group 75 automobile battery was covered snugly by evacuated insulation panels on its front side (electrode side) and two side panels. A representation of the insulated battery is seen in Figure 3. The evacuated panels were the same as in Example 1. The insulated battery was placed in the front of the engine compartment on the passenger side as seen in Figure 2. The other insulated battery was placed on the driver's side. The diesel truck was subjected to the R- 15-61 driving cycle described in Example 1. The temperature performance of the insulated battery was measured as in Example 1. The insulated battery exhibited excellent control of electrolyte temperatures in Figure 6. The two temperatures were significantly different even through 4.5 hours of monitoring. Example 3 An insulated battery of the present invention was tested for its effectiveness in temperature control while in an engine compartment of a gasoline-powered truck. The battery was one of two insulated batteries placed in the engine compartment. A Group 75 automobile battery was covered snugly by evacuated insulation panels on its front side (electrode side) and two side panels. A representation of the insulated battery is seen in Figure 3. The evacuated panels were the same as in Example 1. The insulated battery was placed in the front of the engine compartment on the passenger side as seen in Figure 2. The diesel truck was subjected to the R- 15-61 driving cycle described in Example 1. The insulating performance of the battery was measured by tracking the temperature of the electrolyte within the battery. The insulated battery exhibited excellent temperature control performance as seen in Figure 7. The electrolyte temperature never exceeded 138°F (59°C). While embodiments of the insulated battery and the engine compartment of the present invention have been shown with regard to specific details, it will be appreciated, that depending upon the automobile and the manufacturer's desires, the present invention may be modified by various changes while still being fairly within the scope of the novel teachings and principles herein set forth.

Claims: WHAT IS CLAIMED IS : 1. An engine compartment comprising: A) a heat sensitive component; and B) a corestock of one or more porous or open-celled rigid material matrixes which has been evacuated to an absolute pressure of about 10 torr or less and sealed, and which covers about 20 percent or more of the surface area of the component; optionally, wherein the corestock is situated within an evacuated cavity of the component; or C) an evacuated panel comprising a deformable receptacle which has been evacuated to an absolute pressure of about 10 torr or less and sealed surrounding a corestock of one or more porous or open-celled rigid material matrixes, and which covers about 20 percent or more of the surface area of the component, where the corestock or the evacuated panel provides an R value of 10 per inch or greater. 2. The engine compartment of Claim 1, wherein the corestock of one or more porous or open-celled rigid material matrixes has one or more indentations therein which extend in at least one dimension across a surface of a rigid material matrix, and wherein the receptacle, or an exterior surface of an evacuated cavity of the component, substantially conforms to the shape of the corestock and the indentations therein and the finished panel has surfaces which are substantially non-wrinkled; optionally, further comprising one or more rigid plates having one or more indentations therein, the one or more plates being situated contiguous to a major surface of the corestock 3. The engine compartment of one of the previous Claims, wherein the rigid material matrix of the corestock is an open cell thermoplastic foam, a polycarbonate foam, a thermoset foam, a polyurethane foam, an epoxy -resin foam, a formaldehyde foam, a phenolic foam, an Isocyanurate foam, silica, fiberglass, glass bead, aerogel, or xerogel. 4. The engine compartment of one of Claims 1-2, wherein the rigid material matrix of the corestock is an alkenyl aromatic polymer foam having an average cell size of less than about 70 micrometers, a propylene polymer foam, an extruded foam of coalesced strand configuration, an open channel foam or a perforated foam. 5. The engine compartment of one of the previous Claims, wherein the component is a battery, a computer or a communications device. 6. The engine compartment of one of the previous Claims, wherein the corestock or the evacuated panel provides an R value of about 15 or more per inch. 7. The engine compartment of one of the previous Claims, wherein the absolute pressure within the corestock is about 1.0 torr or less. 8. The engine compartment of one of the previous Claims, wherein the component is a lead acid battery and the engine compartment is an automobile engine compartment. 9. An insulated heat sensitive component comprising: A) a heat sensitive component; and B) a corestock of one or more porous or open-celled rigid material matrixes which has been evacuated to an absolute pressure of about 10 torr or less and sealed, and which covers about 20 percent or more of the surface area of the component; optionally, wherein the corestock is situated within an evacuated cavity of the component; or C) an evacuated panel comprising a deformable receptacle which has been evacuated to an absolute pressure of about 10 torr or less and sealed surrounding a corestock of one or more porous or open-celled rigid material matrixes, and which covers about 20 percent or more of the surface area of the component, where the corestock or the evacuated panel provides an R value of 10 per inch or greater.

Inventors: CORNELL MARTIN C, MOTTER GREGG A, SUH KYUNG W, CORNELL, MARTIN, C., MOTTER, GREGG, A., SUH, KYUNG, W.
Applicants: CORNELL MARTIN C, DOW CHEMICAL CO, MOTTER GREGG A, SUH KYUNG W, CORNELL, MARTIN, C., MOTTER, GREGG, A., SUH, KYUNG, W., THE DOW CHEMICAL COMPANY
Application year: 1998
Main classification: B60R13
IPC codes: B60R13, B60R16, H01M2, H01M10