CA2247782A1

CA2247782A1 - Cavity filled insulation pack

Info

Publication number: CA2247782A1
Application number: CA 2247782
Authority: CA
Inventors: Furio Orologio
Original assignee: Individual
Current assignee: Individual
Priority date: 1998-09-18
Filing date: 1998-09-18
Publication date: 2000-03-18

Abstract

A thermally insulating bubble pack for use in framed structures, walls, crawl spaces and the like; or wrapping for and cold water heaters, pipes and the like wherein the bubbles contain a fire retardant material. The invention also relates to bubble-pack thermal insulation for use as a flexible cooler pack, wherein the bubbles contain a low freezing point liquid or gel. The improved bubble pack comprises a first film having a plurality of portions wherein each of the portions defines a cavity; a second film in sealed engagement with the first film to provide a plurality of closed cavities; the improvement comprising wherein the cavities contain a fluid or solid material. The flame retardant-containing bubble pack provides improved fire ratings, flame spread indices and smoke development numbers. The cooler pack allows of improved topological contact with the surface to be cooled.

Description

CAVITY FILLED INSULATION PACK
FIELD OF TIC INVENTION
This invention relates to bubble-pack thermal insulation materials for use in framed structures, walls, crawl spaces and the like or wrapping for hot and cold water heaters, pipes and the like wherein the bubbles contain a fire retardant material.
The invention also relates to bubble-pack thermal insulation for use as a flexible cooler pack, wherein the bubbles contain a low freezing point liquid or gel.
BACKGROUND TO THE INVENTION
Insulation materials are known which comprise a clean, non-toxic, heat barrier made of aluminum foil bonded to a single or double layer of polyethylene bubbles spaced one bubble from another bubble in the so-called "bubble-pack" arrangement.
Such non-foil bubble-packs are used extensively as packaging material, whereas the metal foil bubble-pack is used as thermal insulation in wood frame structures, walls, attics, crawl spaces, basements and the like and as wrapping for hot water heaters, hot and cold water pipes, air ducts and the like. The reflective surface of the metal, particularly, aluminum foil enhances the thermal insulation of the air-containing bubble pack.
Organic polymers, such as polyethylene, are generally considered to be high-heat-release materials. They can easily initiate or propagate fires because, on exposure to heat, they undergo thermal degradation to volatile combustible products. If the concentration of the degradation products in the air is within flammability limits, they can ignite either spontaneously, if their temperature is large enough, or by the effect of an ignition source such as a spark or flame. The ignition of polyethylene can be delayed and/or the rate of its combustion decreased by means of fire retardant materials.
The ultimate aim of fire retardants is to reduce the heat transferred to the polymer below its limit for self sustained combustion or below the critical level for flame stability.
This can be achieved by decreasing the rate of chemical and/or physical processes taking

2 place in one or more of the steps of the burning process. One or a combination of the following can achieve fire extinguishing:
1. creation of a heat sink by using a compound that decomposes in a highly endothermic reaction giving non-combustible volatile products, which perform a blanketing action in the flame, e.g., aluminium or magnesium hydroxide;
2. enhancements of loss of heat and material from the surface of the burning polymer by melt dripping, e.g., mixture of halogenated compounds with free radical initiators;

3. flame poisoning by evolution of chemical species that scavenge H and OH
radicals which are the most active in propagating thermo-oxidation in the flame, e.g., hydrogen halides, metal halides, phosphorus-containing moieties;

4. limitation of heat and mass transfer across the phase boundary, between thermal oxidation and thermal degradation by creation of an insulating charred layer on the surface of the burning polymer, e.g., intumescent chart; or

5. modification of the rate of thermal volatilization of the polymer to decrease the flammability of the volatile products; which approach strongly depends on the chemical nature of the polymer.
Fire retardant materials are generally introduced to the polyethylene as merely additives or as chemicals that will permanently modify its molecular structure. The additive approach is more commonly used because it is more flexible and of general application.
Regardless of the application method of fire retardant material(s), a satisfactory insulative assembly must have a fire rating of Class A with a flame spread index lower than 16, and a smoke development number smaller than 23. Further, the bonding of the organic polymer films and their ageing characteristics must meet the aforesaid acceptable standards. Yet further, the fabrication methods) of a new fire retardant system or assembly should be similar to the existing technology with reasonable and cost effective modifications to the existing fabrication system/technology. Still yet further, other physical properties of an improved fire standard system must at least meet, for example, the standard mechanical properties for duct materials as seen by existing competitive products.

Fire retardant polyethylene films, wires and cables containing a fire retardant material in admixture with the polyethylene per se are known which satisfy cost criteria and vigorous fire retardant technical standards to be commercially acceptable.
However, it has been found that forming a bubble pack comprising such a film results in a poor bonding between the cavity-containing layer and the adjacent sealing layer used to cover the cavities to form the bubbles. Delamination of these layers, particularly, after installation constitutes a significant problem.
Conventional fire retardant additives are usually compounds of small molecular weights containing phosphorus, antimony, or halogens. The most effective commercially available fire retardant systems are based on halogen-containing compounds.
However, due to concerns over the environmental effects of such halogenated compounds, there is an international demand to control the use of such halogenated additives.
Some of the most common halogenated agents are methyl bromide, methyl iodide, bromochlorodifluoromethane, dibromotetrafluoroethane, dibromodifluoromethane and carbon tetrachloride. These halogenated fire retarding materials are usually available commercially in the form of gases or liquids. Unlike chlorine and bromine, fluorine reduces the toxicity of the material and imparts stability to the compound.
However, chlorine and bromine have a higher degree of fire extinguishing effectiveness and, accordingly, a combination of fluorine and either chlorine or bromine is usually chosen to obtain an effective fire-retarding compounds.
Other commercially available fire retardant materials that do not include halogens include boric acid and borate based compounds, monoammonium phosphonate, and urea-potassium bicarbonate.
Intumescent compounds which limit the heat and mass transfer by creating an insulating charred layer on the surface of the burning polymer are also considered fire retardant materials. A typical intumescent additive is a mixture of ammonium polyphosphate and pentaerythritol.
Fire retardant additives are often used with organic polymer/resins.
Typically, a brominated or chlorinated organic compound is added to the polymer in admixture with a metal oxide such as antimony oxide. Halogenated compounds are also sometimes introduced into the polymer chain by co-polymerization. Low levels i.e. less than 1 W/W are recommended to make adverse effects of halogen-based systems negligible.

Another common fire retardant additive is diglycidyl ether of bisphenol-A with Mo03.
Other additives to improve the fire retarding properties of polyethylene include, for example, beta-cyclodextrin, magnesium hydroxide and alumina trihydrate, tin oxide, zinc hydroxystannate, and chlorosulphonated polyethylene.
Freezer packs comprising a thermoplastic bag, pouch and the like containing an anti-freeze type liquid, gel or the like are known for use as medicinal ice-packs and in transportable, perishable food containers, such as cooler containers and picnic hampers.
However, such pouches, bags and the like are generally formed of a relatively thick, thermoplastics material of low flexibility which, when in its "cold condition"
does not readily adapt to the surface topology of an injured arm, leg, ankle and the like to effect good uniform skin contact.
Such pouches having several compartments formed by the heat sealing or other bonding of opposing surfaces of the pouch are known. However, such compartments are still of such relatively large dimensions that folding of the pouch, particularly, when at a relatively low temperature of, for example, -10°C is still difficult.
There is, therefore, a need for a thermal insulation system having improved fire retardant properties. There is also a need for a "cold-pack" system having improved flexibility and shape adaptability.

Surprisingly, I have found that the fire-retardant assemblies according to the invention have satisfactorily met the dual requirements of acceptable aging properties and bonding strengths, i.e. delamination.
It is one object of the present invention to provide a thermal insulation system for residential and commercial establishments having improved fire retardant properties.
It is a further object to provide a freezer-pack, bag, pouch and the like, having improved flexibility and shape adaptability.
Accordingly, in one aspect the invention provides an improved bubble pack comprising a first film having a plurality of portions wherein each of said portions define a cavity; a second film in sealed engagement with said first film to provide a plurality of S
closed said cavities; the improvement comprising wherein said cavities contain a fluid or solid material.
The terms "cavity" or "cavities" in this specification include voids, bubbles or other like closed spaces. The cavities may be formed of any desired suitable shapes. For example, semi-cylindrical, oblong or rectangular. However, a generally, hemi-spherical shape is preferred.
The bubble pack preferably comprises the cavities being wholly or partially filled with a fire-retardant compound or composition, or a low temperature freezing liquid, gel or the like.
The fire retardant material may be a compound or composition comprising one or more compounds having acceptable fire retardant properties in the form of, for example, a gaseous, liquid or gel fluid contained within the cavity; solid in the form of a particulate powder or dust within the bubble or coating upon the cavity wall.
The amount of fire retardant material is such as to provide an efficacious amount in relation to the amount of plastic and other components present in the bubble pack.
Thus, the amount of fire retardant material required will depend on the application of the assembly, the type and effectiveness of the fire retardant material used, the final properties required e.g. flame spread index, slow burning or self extinguishing, and the bubble size. The fire retardant is generally present in an amount selected from 0.1 - 10%
W/W, preferably 0.5 -- 5% W/W in relation to the thermoplastic film.
Examples of suitable fire retardants of use in the practice of the invention, include those classes and compounds as hereinbefore described.
Most preferably, the bubble pack further comprises one or more foils, layers, films, laminates or the like of a suitable metal, for example, aluminum to enhance reflection of infra-red radiation.
A most preferred plastic is polyethylene, particularly a low-density polyethylene of use as aforesaid first and second films.
The number, size and layout of the bubbles in the pack according to the invention may be readily selected, determined and manufactured by the skilled artisan.
Typically, in a single pack, the bubbles are arrayed in a coplanar off set arrangement.
Each of the hemi-spherical bubbles may be of any suitable diameter and height protruding out of the plane of the bonded films. Typically, the bubble has a diameter selected from 0.5 cm - 5

6 cm, preferably 0.8 - 1.5 cm; and a height selected from 0.2 cm - 1 cm, preferably 0.4 -0.6 cm. A preferred bubble pack has an array of about 400 bubbles per 900 cm2.
BRIEF DESCRIPTION OF THE DRAWINGS
In order that the invention may be better understood, preferred embodiments will now be described by way of example only, with reference to the accompanying drawings, wherein Fig. 1 is an isometric view of a wall insulation panel comprising a bubble-pack assembly according to the prior art;
Fig. 2 is an isometric view of a wall insulation panel comprising a bubble-pack assembly according to the invention;
Fig. 3 is a foldable freezer bubble pack assembly according to the invention;
Fig. 4 is a roll of bubble film of use in the pack according to fig. 3;
Fig. 5 is a sheet of film of use in the pack according to Fig. 3;
Fig. 6 is a diagrammatic, isometric view, in part, of a bubble pack-forming apparatus according to the invention;
Fig. 7 is a modified version of the apparatus of Fig. 6 having enlarged diagrammatic cross-sectional views shown as Figs. 7A and 7B; and wherein the same numerals denote like parts.
DETAILED DESCRIPTION OF PREFERRED EMBODIIVVIENTS
With reference to Fig. 1, this shows generally as 10, a prior art double layer, bubble-pack insulation assembly double layer, consisting of a pair of bubble arrays 12, 14 bonded together through an intervening low density polyethylene film 16.
Arrays 12, 14 are formed of a plurality of bubbles or sealed cavities 18, 20, respectively, from a 5 mil polyethylene film 22, 24, respectively. Each of films 22, 24 is bonded to a reflective aluminum foil 26, 28, respectively.
Assembly 10 has approximately 20, 1 cm diameter, 0.5 cm high bubbles per 30 cm length and breadth within each of films 22, 24.

The aforesaid assembly 10 is made by a double hot roller thermal and vacuum forming process for cavity forming and lamination sealing techniques known in the art, and has a fire rating of Class A/Class 1, a flame spread index of 16 and a smoke development number of 23. However, improvements in these ratings are required for new applications such as, for example, thermal insulation for heating and ventilation ducts.
Fig. 2 shows the embodiment described with reference to Fig. 1 wherein each bubble 18, 20 contains 5% W/W aluminum hydroxide fire-retardant 30 relative to the amount of low density polyethylene resin.
The aluminum hydroxide fire retardant 30 may be added to cavities 18, 20 by any suitable manual or automated method. In alternative embodiments, alternative retardants may be added by gas or liquid fluid injection or as a poured or blown particulate solid insertion method.
With reference now to Fig. 3, this shows, generally, as 100 a double-bubble freezer-pack assembly according to the invention wherein bubbles 18 contain an antifreeze gel having a freezing point below -40°C. In consequence of the plurality of the relatively small diameter, gel-filled flexible polyethylene bubbles, the assembly can be readily folded or coiled, and sealed by means of a "zip-lock" engageable portions 102 at one end 104 of bubble pack 100.
Figs. 4 and 5 show diagrammatic views of film according to the invention in the form of a roll and planar sheet, respectively.
The apparatus shown in Fig. 6, generally as 200, has an endless belt conveyer mould shown generally as 210 with which a film of thermoplastics material 202 operably moves in the direction L-R of the arrow under the influence of a sprayer or dispenser 212, scraper 214, heaters 216 and nip roller 218, further described hereinbelow.
A pre-heater 220 at a suitable temperature disposed below film 202 softens film 202 to just below its melt temperature of, for example, 90 - 95°C for polyethylene.
Mould 210 has an endless belt of segmented aluminum elongate members 222 movable by means of terminal rotating cog and sprocket assemblies (not shown).
Each of members 222 has portions defining semi-spherical cavities 224 intermittent along the width of member 222 and offset to adjacent cavities 222 on adjacent members 222. Each of cavities 222 has an aperture 226 to provide a suctional force on the soft film for the film to be pulled onto the inside cavity surface, by a vacuum pump (not shown).
Disposed above softened film 202 adjacent the feed end 228 of apparatus 200, is an elongated feed conduit sprayer 212 having a plurality of exit apertures 232 which direct filler material 234 in the form of particulate solid, e.g. powder, or liquid, gel, emulsion into each cavity 222. Although the spraying of material 234 may be suitably mechanically or electronically controlled to dispense material 234 only wherein a cavity 222 is directly beneath an individual aperture 232, I have found that sufficient resultant adhesion between film 202 and covering film 236, subsequently bonded to film 202, as hereinafter described, can be obtained by means of scraper 214 horizontally, diagonally disposed on film 202 to scrape off excess material.
Heater system 216 disposed above cavity-filled film 202 maintains the softness of film 202 in addition to softening film 236 fed in arrow direction T-B prior to its melding and bonding with film 202 under nip roller 218 to form cavity-filled bubble pack film 238.
The size, shape and arrangement of the cavities in the film may be as suitably determined by the skilled person. The temperatures of films 202, 236 as well as film throughput rate can be readily selected by the skilled person. Throughput rates of the magnitude of 50 meters/minute are preferred.
Although this disclosure has described and illustrated certain preferred embodiments of the invention, it is to be understood that the invention is not restricted to those particular embodiments. Rather, the invention includes all embodiments which are functional or mechanical equivalents of the specific embodiments and features that have been described and illustrated.

Claims

1. An improved bubble pack comprising a first film having a plurality of portions wherein each of said portions defines a cavity; a second film in sealed engagement with said first film to provide a plurality of closed said cavities; the improvement comprising wherein said cavities contain a fluid or solid material.

2. A bubble pack as defined in claim 1 wherein said material is a fire retardant material.

3. A bubble pack as defined in claim 1 wherein said fluid is a low temperature freezing liquid or gel.

4. A pack as defined in any one of claims 1 - 3 further comprising a layer of a metal or a metallized film adjacent said second film.

5. A pack as defined in any one of claims 1 - 4 wherein at least one of said first and second film is formed of a thermoplastic material.

6. A pack as defined in claim 5 wherein said first and second films are so flexible as to allow said pack to be rolled to define in whole or in part a cylinder.

7. A pack as defined in claim 5 wherein said first and second films are so flexible as to allow of folding of said pack one face upon itself.

8. A pack as defined in any one of claims 1 - 8 comprising at least two of said packs in abutment one pack adjacent another of said packs

9. A pack as defined in any one of claims 1 - 9 comprising a coplanar array of bubbles having a diameter selected from 0.5 cm - 5 cm and a height selected from 0.2 cm - 1 cm.