EP1768875A2

EP1768875A2 - Insulation process

Info

Publication number: EP1768875A2
Application number: EP05857696A
Authority: EP
Inventors: Timothy J. Lindquist; Michael D. Swan; Sithya S. Khieu
Original assignee: 3M Innovative Properties Co
Current assignee: 3M Innovative Properties Co
Priority date: 2004-07-01
Filing date: 2005-06-29
Publication date: 2007-04-04
Also published as: WO2006098745A2; CA2572590A1; JP2008505009A; CN1980817A; KR20070037632A; BRPI0512862A; WO2006098745A3

Abstract

A process for insulating a vehicle comprises providing a vehicle (for example, an automobile, truck, train, boat, ship, or aircraft; preferably, an aircraft) with an insulation system comprising at least one insulation article comprising a substantially closed bag containing a foam composition that is capable of subsequent in situ solidification to form foam insulation.

Description

INSULATION PROCESS

STATEMENT OF PRIORITY

This application claims the priority of U.S. Provisional Application No. 60/584,587 filed July 1, 2004, the contents of which are hereby incorporated by reference.

FIELD This invention relates to processes for providing thermal and/or acoustic shielding to, for example, transportation vehicles such as aircraft.

BACKGROUND

Blankets providing thermal and/or acoustic insulation are used in aircraft and other vehicles to shield passengers from engine and aerodynamic noise and from temperature extremes. One problem with such blankets is moisture uptake. This problem is particularly significant in aircraft, where weight increases due to water entrapment in the blankets can be dramatic.

A commercial airliner at cruising altitude experiences exterior temperatures significantly below freezing, often temperatures as low as -4O⁰C. The passengers and crew of the aircraft produce significant amounts of water vapor within the fuselage, and this water vapor tends to condense on cold surfaces presented either on the interior cabin wall, within the insulation in the space between the interior cabin wall and the exterior skin of the aircraft, or on the inside of the exterior skin. Condensation on the interior cabin wall is undesirable from a passenger comfort aspect. Condensation within the insulation is undesirable because it decreases the efficiency of the insulation and because the added weight from the condensed water increases the cost of operation of the aircraft and decreases its payload capacity. Condensation on the inside of the exterior skin can cause corrosion of the skin and the various structural members attached thereto, resulting in decreased lifetimes for the various components and in the need for periodic inspections to check for and repair or replace the corroded components. Such inspections in turn require that the insulation system be readily removable.

This condensation problem could be largely eliminated if an optimized insulation system could be used. The most common insulation system in use today comprises bats of fiberglass that are enclosed by water-impermeable membranes. The membranes are in turn provided with small holes to prevent ballooning problems within the walls with the inevitable changes in pressure that occur as an airplane changes altitude.

These fiberglass blankets must be custom made for each aircraft type, and, for each type, many individually different patterns must be used in order to effectively provide insulation to the space between the interior cabin wall and the exterior skin while avoiding interference with the various structural and other assemblies also inside this space. Thus, these thermal blankets are expensive and difficult to install and maintain.

The fiberglass blankets work well when initially installed. However, the necessary holes in the exterior membrane allow water to enter into the blankets. It is estimated that this water can increase the weight of the thermal blanket three-fold within a three-year period of typical airline service.

The industry has searched for alternative insulation systems to overcome the above-described drawbacks and shortcomings of the conventional fiberglass blankets.

Some have turned to various types of foam systems including, for example, foam- containing blankets; preformed rigid foam panels; blankets comprising fiberglass layers alternated with semi-rigid foam layers; and formed-in-place (for example, by spray application) rigid or semi-rigid, closed-cell foams.

Although such foam systems provide improvements in certain respects over the fiberglass blankets, the preformed panels and the blankets are still costly (as they must be provided in a large number of different shapes and sizes, etc.), and the formed-in-place, rigid and semi-rigid foams can be difficult to remove for inspections. Removability has been addressed by the use of more flexible, formed-in-place foams supported by a barrier material, but such systems can still pick up and retain some moisture, and their installation can involve worker exposure to volatile organic compounds during the installation process. SUMMARY

Thus, we recognize that there is a need for vehicle insulation processes (and, in particular, processes for insulating aircraft) that make use of insulation articles that can be easily manufactured and installed, that provide effective thermal and/or acoustic shielding without significant moisture uptake and/or retention, and that can be easily removed from the vehicle (for example, to enable article repair or replacement and/or vehicle maintenance or repair).

Briefly, in one aspect, this invention provides such a process, which comprises providing a vehicle with an insulation system comprising at least one insulation article comprising a substantially closed bag containing a foam composition that is capable of subsequent in situ solidification to form foam insulation. The vehicle can be, for example, an automobile, truck, train, boat, ship, or aircraft (preferably, an aircraft; more preferably, a commercial aircraft; most preferably, a commercial jet that has a passenger capacity of at least about 100). As used herein, "substantially closed" means that the bag encloses the foam composition but can comprise one or more openings such as, for example, an inlet or entry port and any of various pressure control devices such as vents, holes, or valves. The foam composition can be a foamable composition or a composition that has already been at least partially foamed. The bag is preferably a flexible bag (more preferably, a flexible, oversized bag).

It has been discovered that, relative to at least some conventional foam insulation systems, a reduction in moisture problems can be achieved by using a formed-in-place foam insulation system that employs substantially closed bags to contain the foam composition. Following installation of the insulation system and in situ solidification of the foam composition, the bags remain in place and can reduce the exposure of the resulting foam insulation to moisture.

Thus, the insulation articles used in the process of the invention are easy to manufacture and install and can provide effective thermal and acoustic insulation with reduced loss of effectiveness (and reduced weight gain) due to moisture uptake and/or retention. The bags can hold the foam insulation in place and prevent it from sticking to the surface of the vehicle, thereby making it easier to remove than some conventional foam insulation systems. At least some embodiments of the process of the invention therefore meet the need for processes that provide effective thermal and/or acoustic shielding without significant moisture uptake and/or retention problems and that also enable easy removability.

DETAILED DESCRIPTION

Insulation Articles

Insulation articles that are useful in carrying out the process of the invention include those that comprise a substantially closed bag containing a pre-solidified foam composition that can subsequently solidify in situ to form foam insulation. The bag can comprise essentially any material that is substantially inert to the foam composition that is utilized (sufficiently inert that the integrity of the bag can be maintained).

Preferably, the bag is made of a flexible material, so as to permit deformation of the article during installation to accommodate structural protrusions, etc., on the vehicle surface. Useful bag materials include polymer films (for example, polyimide film, fluoropolymer films, flame-retardant polyester films, and combinations thereof), metal foils (for example, aluminum foil, copper foil, tin foil, and combinations thereof), woven or nonwoven materials, papers and treated papers, and combinations thereof. Preferred bag materials include polymer films, metal foils, and combinations thereof. The bag can be be single- or multi-layer in nature and can be preformed. For example, the bag can be custom made to the required dimensions for any given location within a particular vehicle and then completely filled with foam composition. Alternatively (and preferably), an oversized bag (larger than the installation location) of a standard shape and size can be useful, for example, when only partially filled with foam composition. (During solidification of the foam composition, any surplus bag material can be, for example, "caught up" in the resulting foam.) The bag can be elastic and expandable (for example, like a balloon) and can be of any useful shape. For example, the bag can be designed to have finger-like protrusions that can be filled with foam composition and used to insulate around surface protrusions, etc. If desired, the bag can be integral to, for example, at least one interior panel of the vehicle (for example, an aircraft interior panel). The foam composition can be a foamable composition or a composition that has already been at least partially foamed. After foaming and subsequent solidification (for example, through curing), the resulting foam insulation can comprise an open cell foam, a closed cell foam, or a combination thereof. Useful foam compositions include, for example, acrylic polymers, polyolefin (for example, polyethylene, polypropylene, ethylene vinyl acetate copolymers, ethylene acrylic acid copolymers, ionomers of ethylene and mixtures thereof), polyurethane, polyisocyanurate, polyimide, natural and synthetic rubbers, silicone, and blends thereof, as well as polymer precursors thereof (for example, monomers or oligomers). Preferred are those compositions that provide foams that are relatively hydrophobic, fire-resistant, and thermally and acoustically insulating.

The foam composition can optionally further comprise one or more additives such as tackifiers, plasticizers, pigments, dyes, expandable or non-expandable microspheres, physical blowing agents, chemical blowing agents, foam stabilizers, surfactants, reinforcing agents, hydrophobic or hydrophilic metal oxides, calcium carbonate, toughening agents, catalysts, accelerators, fire retardants, antioxidants, finely ground polymeric particles, stabilizers, continuous microfibers, curing agents, crosslinkers, and the like, and mixtures thereof.

Foams can be prepared by forming gas voids in the composition using any of a variety of mechanisms including, for example, mechanical mechanisms, chemical mechanisms, addition of glass microspheres, and combinations thereof. Useful mechanical foaming mechanisms include, for example, agitation (for example, shaking, stirring, or whipping the composition, and combinations thereof), injecting gas into the composition, and combinations thereof. Useful chemical foaming mechanisms include, for example, producing gas in situ through a chemical reaction, through decomposition of a component of the composition (including, for example, a component that liberates gas upon thermal decomposition), evaporating a component of the composition, volatilizing a gas in the composition by decreasing the pressure on the composition or by heating the composition, and combinations thereof. In principle, any foaming agent can be used to foam the composition including, for example, chemical foaming agents and physical foaming agents (including, for example, inorganic and organic foaming agents). The foaming agents can be used as single components or in mixtures and can be added to the composition in an amount sufficient to achieve a desired foam density.

One or more nucleating agents can also be present in the foam composition. The amount of nucleating agent to be added depends upon the desired cell size, the selected foaming agent, and the density of the composition being foamed.

The components of the foam composition can be separately transferred to the bag and mixed during or after transfer. Preferably, however, the foam composition is pre- mixed (and, optionally, pre-foamed) before being transferred (for example, by spraying, pumping, pouring, or injection) to a bag. Foaming can also be effected during or after transfer.

To enable transfer of the foam composition, the bag can comprise an inlet or entry port and/or a filling hole, which can be as simple as a slit in the bag (which can then be taped over after filling) or can be more complex in nature such as a hole equipped with a one-way valve (for example, a simple flap valve that flaps out of the way as the foam composition is transferred and then closes as the foam composition pushes against it from the inside of the bag). The bag can also comprise one or more pressure control devices (for example, vents, holes, or valves).

To enable periodic vehicle inspections, the foam can be designed to facilitate its removal. For example, the foam can be designed to be pliable and soft enough to be pulled out around any protrusions in the vehicle structure. The foam can also be broken as it is removed, and new insulation can be installed on return to service. The foam can alternatively be designed so that it collapses on exposure to a particular chemical or condition, enabling its removal from the bag using a reverse transfer process (for example, by pouring it or pumping it out of the bag).

Other materials and layers conventionally found in insulation blankets can be included in the insulation articles. For example, the article can further comprise one or more high-temperature resistant materials (including, for example, materials that are resistant to flame propagation and/or flame penetration), one or more adhesive compositions or films, one or more scrims (for example, woven or nonwoven material or netting), one or more water repellent coatings, one or more intumescent additives or coatings, one or more reflective films (for example, for controlling radiant energy), and one or more polymer films (which can optionally be metallized), as well as flame retardants, antistatic agents, anti-mildew agents, and the like. The insulation articles can further comprise one or more attachment devices for use in attaching the articles to each other and/or to the vehicle. Useful attachment devices include adhesives (for example, pressure-sensitive adhesives or non-tacky adhesives), re- closable fasteners (for example, hook and loop fasteners or dual lock fasteners), mechanical interlocks (for example, tongue and groove, buttons and button holes, snaps, and shaped "puzzle-like" edges or structures), clips, pins, and the like, and combinations thereof. The attachment devices are preferably an integral part of the article, but separate attachment devices can be utilized, if desired.

The articles can be of any shape and size that facilitates coverage of a vehicle surface. If desired, the shapes can be designed to match the shapes of vehicle surfaces (for example, to form custom-shaped bags) and can be provided with one or more cuts or holes to accommodate surface protrusions, etc. Representative examples of usefully shaped articles include spherical articles and "two-dimensional" panels or sheets or thicker versions thereof (three-dimensional "solids") that are, for example, square (six faces), rectangular (six faces), triangular (five faces), hexagonal (eight faces), octagonal (ten faces), doughnut-shaped, and the like. The particular shape and size of the articles that is chosen for carrying out the process of the invention will vary, depending, for example, upon the size of the vehicle and its surface configurations.

Insulation System and Process The pre-solidified foam composition can be transferred to the bag either before or after the bag is provided to the vehicle. However, solidification of the foam composition preferably occurs (is effected in situ, for example, by activation of a curing agent, or is allowed to occur in situ) after both transfer of the foam composition and installation (positioning in its ultimate location in or on the vehicle by, for example, placing, applying, or attaching) in the vehicle have been carried out. This allows the pre-solidified foam composition to solidify (for example, by curing or crosslinking) in a shape that conforms to that of the space in the vehicle for which the insulation article is to provide coverage. Such conformance can also be achieved, however, by using a custom-shaped bag, which can be installed after solidification has already occurred, if desired. Partial solidification can be effected prior to installation, if desired.

The vehicle can be provided with the insulation articles in any desired manner (for example, by bringing the articles in or on the vehicle or one or more of its components, for example, by placement, application, or attachment). Thus, the insulation articles can, for example, be attached to the vehicle and/or to each other to form the insulation system. This can be accomplished using any attachment device that is capable of use with the materials comprising the insulation articles and with the vehicle surface. For example, the insulation articles can be coated with a first adhesive that will adhere only to itself and will release when pulled upon. Such an adhesive generally cannot aggressively bind dirt or other contaminants. A second adhesive can be used to attach the insulation articles to the vehicle surface. Alternatively, mechanical fastening systems can be used to attach the articles to each other, and an adhesive can be used to attach the articles to the vehicle surface.

In addition to the foregoing methods, numerous other possible methods of providing the vehicle with the articles can be envisioned by the skilled artisan. The insulation process of the invention is particularly useful in insulating aircraft by providing (for example, applying or attaching) the insulation system to an area anywhere between and including (i) the interior surface of the exterior skin of the aircraft and (ii) the exterior surface of the interior compartments of the aircraft (including the underside of the floor of the passenger compartment). The insulation articles can be designed to be flexible enough to push around irregular shapes on the aircraft surface or can simply be positioned to allow wire penetrations, etc. For insulating the aircraft frame, the insulation articles can be designed to be sufficiently stiff yet elastic to enable them to be snapped into place over the frame. Such insulation articles can insulate the frame and also provide attachment sites for the remainder of the insulation system.

Examples Objects and advantages of this invention are further illustrated by the following examples, but the particular materials and amounts thereof recited in these examples, as well as other conditions and details, should not be construed to unduly limit this invention. Materials

Foam Types 1) RT-5090-60 Polyurethane Packaging Foam system (an 8.0 kg/m³ water-blown, open- celled, general purpose, low density polyurethane foam system available from Resin Technology Company (a Division of the Henry Company), Ontario, California)

2) SWD 500.75 Packaging Foam system (a polyurethane foamable material available from SWD Urethane Company, Mesa, Arizona)

3) SWD 500.4 Fire Retardant Packaging Foam system (a polyurethane foamable material available from SWD Urethane Company, Mesa, Arizona)

Bagging Materials

1) Orcofilm™ AN-54W polyvinyl fluoride film (a heat-sealable, metallized polyvinyl fluoride film available from Orcon Corporation, Union City, California)

2) Mylar™ SBL polyester film (a multilayer, polyester-based film having a metallized coating and heat sealable layers, available from Dupont Teijin Films™, Hopewell,

Virginia)

3) Kapton™ polyimide film (a polyimide film, available from DuPont High Performance Materials, Circleville, Ohio)

Example 1

A foamed-in-place insulation article is prepared in the following manner:

Orcofilm™ AN-54W polyvinyl fluoride film is cut into two pieces each measuring 1 meter square (m²). A tab piece measuring 105 millimeters (mm) long and 25 millimeters wide is provided from the same film. The tab piece is attached at one end to approximately the center of the first piece of film and at the other end to approximately the center of the second piece of film by means of heat sealing. The attachment area of each end of the tab piece measures 15 mm by 25 mm. The two pieces of film are superimposed and then sealed together at their peripheral edges by means of heat sealing, so as to form a bag. An opening into the bag is provided by cutting two slits, each measuring 25 mm long, in an "X" orientation near one corner of one of the pieces of film. Part of the exterior surface of the other piece of film is treated with 3M™ Super 77™ Spray Adhesive (an aerosol spray adhesive available from 3M Company, St Paul, Minnesota).

The adhesive-treated side of the bag is then attached to a vehicle (for example, an aircraft) to be insulated. RT-5090-60 Polyurethane Packaging Foam system is then introduced into the bag via the opening and allowed to foam in place. Excess foam is trimmed from the opening to provide a foamed-in-place insulation article attached to the vehicle.

Example 2

A foamed-in-place insulation article is prepared and attached to a vehicle as described in Example 1, with the following modification: the edges of the top and bottom film pieces are joined together using Orcotape™ OT-54W (a reinforced, metallized, pressure sensitive polyvinyl fluoride tape, available from Orcon Corporation, Union City, California).

Example 3

A foamed-in-place insulation article is prepared and attached to a vehicle as described in Example 1, with the following modification: four tab pieces symmetrically positioned approximately 0.33 m from the edges of the film pieces are employed.

Example 4

A foamed-in-place insulation article is prepared and attached to a vehicle as described in Example 2, with the following modification: Mylar™ SBL polyester film is used instead of Orcofilm™ AN-54W polyvinyl fluoride film.

The referenced descriptions contained in the patents, patent documents, and publications cited herein are incorporated by reference in their entirety as if each were individually incorporated. Various unforeseeable modifications and alterations to this invention will become apparent to those skilled in the art without departing from the scope and spirit of this invention. It should be understood that this invention is not intended to be unduly limited by the illustrative embodiments and examples set forth herein and that such examples and embodiments are presented by way of example only, with the scope of the invention intended to be limited only by the claims set forth herein as follows:

Claims

We Claim:

1. A process comprising providing a vehicle with an insulation system comprising at least one insulation article comprising a substantially closed bag containing a foam composition that is capable of subsequent in situ solidification to form foam insulation.

2. The process of Claim 1, wherein said vehicle is selected from the group consisting of automobiles, trucks, trains, boats, ships, and aircraft.

3. The process of Claim 1, wherein said vehicle is an aircraft.

4. The process of Claim 1, wherein said bag comprises a flexible material.

5. The process of Claim 1, wherein said bag is an oversized bag.

6. The process of Claim 1, wherein said bag comprises at least one material selected from the group consisting of polymer films, metal foils, woven materials, nonwoven materials, papers, treated papers, and combinations thereof.

7. The process of Claim 6, wherein said material is selected from the group consisting of polymer films, metal foils, and combinations thereof.

8. The process of Claim 1, wherein said bag is an integral part of at least one interior panel of said vehicle.

9. The process of Claim 1, wherein said bag comprises at least one entry port.

10. The process of Claim 1, wherein said foam composition comprises at least one material selected from the group consisting of acrylic polymers, polyolefin, polyurethane, polyisocyanurate, polyimide, natural and synthetic rubbers, silicone, blends thereof, and polymer precursors thereof.

11. The process of Claim 1, wherein said foam composition comprises at least one curing agent or at least one crosslinker.

12. The process of Claim 1, wherein said process comprises transferring said foam composition to said bag.

13. The process of Claim 12, wherein said transferring is carried out by spraying, pumping, pouring, or injection.

14. The process of Claim 1, wherein said process comprises installing said bag in said vehicle.

15. The process of Claim 1, wherein said process comprises solidifying said foam composition in situ.

16. The process of Claim 15, wherein the resulting foam insulation comprises an open cell foam, a closed cell foam, or a combination thereof.

17. A process comprising providing an aircraft with an insulation system comprising at least one insulation article comprising a substantially closed, oversized bag containing a foamable composition that is capable of subsequent in situ solidification to form foam insulation.

18. The process of Claim 17, wherein said process comprises (a) installing an oversized bag in said aircraft; (b) transferring said foamable composition to said oversized bag; (c) foaming said foamable composition; and (d) solidifying said foamable composition in situ to form foam insulation.

19. The process of Claim 17, wherein said aircraft is a commercial aircraft.

20. The process of Claim 19, wherein said commercial aircraft is a commercial jet that has a passenger capacity of at least about 100.

21. A process comprising providing a vehicle with an insulation system comprising at least one insulation article comprising a substantially closed bag containing a pre-solidified foam composition that subsequently solidifies in situ to form foam insulation.