WO2008086436A1

WO2008086436A1 - Specification insulating sheet

Info

Publication number: WO2008086436A1
Application number: PCT/US2008/050658
Authority: WO
Inventors: Thomas Hicks; Keith Wayne Larson; Bach Nguyen; Yasuo Negishi; Hiroki Mori; Masaaki Sato; Takuo Suzuki; Makiko Sakurazawa
Original assignee: Artscape, Inc.
Priority date: 2007-01-09
Filing date: 2008-01-09
Publication date: 2008-07-17

Abstract

An insulating transparent sheet transmits visual light, and cuts infrared light and is resistant to climate and thermal deterioration even in an environment of outdoor use. In one embodiment, the insulating sheet comprises a vinyl sheet being substantially transparent and configured to attach to a window. Metal particles are dispersed within the vinyl sheet and provide thermal insulation by preventing different thermal light waves from passing through the vinyl sheet. The metal particles also being small enough (or tuned) to allow other visual light waves to pass through the vinyl and substantially maintain the transparency of the vinyl sheet. This relatively thin, substantially transparent thermal film provides immediate and year round energy savings by insulating against heat loss in winter and solar heat gain in summer.

Description

SPECIFICATION INSULATING SHEET

BACKGROUND OF THE INVENTION

Field of the Invention

The invention relates generally to window films.

Background

Windows are one of the places where heat readily escapes or enters buildings. For example, during the winter (up to 40% of home energy is lost through the home windows) heat from a room may more easily escape through a window than through the walls, thus undesirably reducing the temperature in the room. During the summer, solar heat from outside may more readily enter windows, thus undesirably increasing the temperature inside the building.

Several techniques are currently used to reduce the amount of heat allowed to escape through windows. One technique uses a second storm window or a double paned glass. These techniques are expensive and can detract from the inside and outside aesthetics of the building.

Another technique applies a reflective window film to the window that prevents light and energy waves from passing through. These reflective window films have a reflective surface that prevents substantial amount of visible light waves from passing through the window. These reflective window films operate like a two-way mirror where images can only be seen from the darker side of the window. The other brighter side of the window and film appears as a mirror to persons looking through to the opposite darker side of the window and film. This "mirror effect" detracts from the aesthetics of the home and reduces the amount of visual light that is allowed into the home.

It is also difficult to apply these reflective films to glass. For example, the films are very thin and have a tendency to crinkle or crease when being attached to a window. These reflective window films also use adhesives that are difficult to apply to a window and are even more difficult to detach from the window when the initial film application is misaligned. A second non-adhesive sheet is attached over the adhesive layer and then removed prior to applying the film to glass. Just removing this non-adhesive sheet from the adhesive surface of the reflective window film is difficult and further complicates the application process.

The sunlight comprises visible light rays of 380 to 780 nm (in wavelength), ultraviolet light rays of 200 to 380nm and infrared light rays of 780 nm or more in wavelength. Especially, near infrared light rays of 780 to 2,100 nm in wavelength are so-called "heat rays", and easily converted into heat when light is irradiated.

Colored films, metallized films, etc. have been proposed to reduce rise in temperature caused by near infrared light rays in the sunlight. Although these films show an effect to cut heat rays, as well as visible light rays thereby the film having less transparency and visibility problems when applied on a window glass.

There have also been proposed films comprising Indium-doped Tin Oxide (hereinafter referred to as ITO) and Antimony-doped Tin Oxide (hereinafter referred to as ATO) as an infrared light protective material having higher transmittance in the visible light region compared with the above mentioned colored or metallized films (see, Japanese Patent-A No. 2004-91589, etc.)

However, in case of ITO, the wavelength of 900nm or higher can be filtered but difficult to block at wavelengths between 780 to 900 nm. Thus, in order to obtain a desirable level of sunlight cutting performance, the amount of ITO should be increased. Further, when ITO is applied on the surface of films by means of metallizing or sputtering, the surface in appearance tends to glare undesirably because of reflection.

With regard to ATO, the wavelength where light rays are initially filtered also lies slightly to the longer wavelength side although it is not more than that of ITO, while some light rays are absorbed even in the visible light region, which makes the film dark. It is a problem that the transmittance of visible light rays might be further decreased, in order to obtain a required performance of sunlight cutting. Further, in fact, antimony itself has toxic consequences. [0005]

On the other hand, slightly reduced-Tungsten Oxide and Molybdenum Oxide membranes have been disclosed in Japanese Patent-A No. 8-59300, etc. These membranes are well known as a so-called electro-chromic material, which is transparent in a fully oxidized state but absorbs light rays in a region from visible light to near infrared light when the material is reduced by an electrochemical process.

Conventional sunlight shielding materials added with Tungsten Oxide or molybdenum Oxide are prepared by means of sputtering. In such a physical surface modification method, however, large-scaled equipments and vacuum units are necessary for the process, thereby unexpectedly increasing the cost of production even though the productivity is improved and large size products can be yielded.

Furthermore, it has been required from a standpoint of practical use of sunlight-shielding materials to improve the light transmittance in the visible light region without decreasing the cutting performance in the infrared. The performances change due to oxidation or decomposition in a single layer, while durability thereof is also a point of question.

The above mentioned insulating sheets may be used in the open air, for example, film for window glass or an awning. The sheet is exposed not only to rain or cleaning fluid but also to the ultraviolet light which accelerates deterioration of resins and decreases physical properties as well as heat shielding performance. Even though, it is difficult to keep sufficient higher transparency of visible light or haze for a long period of time.

SUMMARY OF THE INVENTION

A sheet/film for heat/thermo shielding from the sun light with highly transparency in visible light region cuts the infrared light region. The light in the infrared region is so-called "heat rays" and enhances thermal built up when irradiate to the objects. An infrared absorbing sheet/film is provided with high visible light transparency and improved weatherability. Better weatherability makes it possible to use the sheet/film under sunlight and severe thermal environment.

Accordingly, a transparent insulating sheet is provided that exhibits an excellent heat light shielding effect and has improved weatherability and thermal stability. It maintains transparency of visible light for a long period of time even when exposed to the sunlight. This relatively thin, substantially transparent thermal film provides immediate and year round energy savings by insulating against heat loss in winter and solar heat gain in summer.

Brief Description of the Drawings FIG. 1 is a drawing showing a thermal window film attached to glass.

FIGS. 2 A and 2 B are drawings showing other embodiments of the thermal window film.

FIGS. 3A and 3B are graphs showing how the thermal window film filters certain heat waves while not filtering visual light waves.

FIGS. 4 A and 4B shows test results of how the thermal window film retains heat inside of a building.

FIGS. 5A and 5B show test results of how the thermal window film prevents heat penetration into a building.

FlG. 6 is a diagram of a laminated vinyl/polyester window film.

DETAILED DESCRIPTION

FlG. 1 shows a thermal window film 12 that is applied to the surface of a window 13 or some other piece of glass. In one example, the window film 12 is made from a static cling vinyl substrate material that attaches to the window 13 from cohesion and atmospheric pressure as described in co-pending patent application, Ser. No. 10/84,904, filed May 13, 2004, entitled: TEXTURED WINDOW FILM, which is herein incorporated by reference.

Polymeric Film Substrate

In one example, at least an inside window contact surface 15 of the thermal film 12 is substantially flat and smooth so that it can be easily attached to the window 13. This inside surface 15 is accordingly held onto the window 13 by cohesion and atmospheric pressure without having to use adhesives. However, this is only one example, and it is also possible to use an adhesive on inside surface 15 to attach the thermal film 12 to window 13.

The polymeric film 12 can be any type of translucent, transparent, or clear material. In one example, the polymeric film 12 is a polyvinyl material that can be any thickness but in one example is anywhere between 0.5 thousands of an inch (mils) and 10 mils. In one embodiment, the polymeric film 12 is transparent and in other embodiments the film 12 may be colored or have varying degrees of opaqueness. In yet another embodiment, the polymeric film 12 also has an outside textured surface as described in co-pending U.S. Patent App. Ser. No. 10/84,904 which is incorporated by reference.

Therm al_Characteristics

Of particular interest are metallic micro fibers or particles 14 that are distributed within the polymeric film 12. These metallic micro-particles 14 interact with certain heat waves to improve the insulating characteristics of the window film 12. The metallic particles 14 filter or insulate heat waves while at the same time allowing the passage of visual light waves. This provides the substantial combined advantage of providing increased heat insulation while at the same time providing a substantially clear or transparent window film 12.

To explain in more detail, different types of Ultra- Violet (UV) light waves 16, visual light waves 18, and heat (infrared) waves 20 may be transmitted or radiated from either side of the window 13. In this example, it may be summer and the temperature on the outside 22 of a window 13 maybe hotter than the temperature on the inside 24 of a building that contains window 13.

The UV light waves 16A from outside location 22 are reflected or dispersed by any combination of the polymeric film 12, the glass 13, the non-homogeneous interface between glass 13 and polymeric film 12, UV inhibitors that may reside within the polymeric material in film 12, micro fibers or micro particles 14 and by a chemical additive for light stabilization called benzophenone. This is represented by reflected UV waves 16B that are prevented from passing through the thermal film 12. Tests have determined that the micro particles 14 may only contribute around 3-5% of the UV filtering provided by thermal film 12. The addition of these stabilizers and the combination of a controlled production process leads to a very reliable and durable product. The finished product has been tested in a weatherometer for over 2000 test hours with no problems or deterioration of product performance. These 2000 test hours simulates over 10 years of product life in normal weather conditions.

Of further importance are the visual light waves 18 generated from the location 22 outside of window 13. This embodiment of the polymeric film 12 allows up to 85% of the visual light waves 18 to pass through the window 13 unfiltered. This results in the window film 12 appearing substantially transparent to a person located at an inside location 24 viewing out of window 13 to a person located at an outside location 22 viewing into window 13.

Thus, the thermal film 12 does not have the mirrored reflective surface typically used in existing thermal window films. This improves the overall aesthetic effect of the window film 12 on window 13 allowing persons to see out of window 13 both during the day and also at night and it allows the visible light into the room so the room is not as gloomy in the winter time. In another example, the window 13 may be stained glass, textured, or etched. By not filtering or reflecting the visual light waves 18, these aesthetic characteristics of glass 13 can still be seen both from the inside 24 and outside 22 after the window film 12 is attached.

The metallic particles 14 also create another characteristic in window film 12 that filters, retains, or reflects a substantial amount of heat waves 2OA. The metallic particles may absorb some of the heat waves 2OA and reflect or disperse some additional portion 2OB of the heat waves 2OA. The result is a substantially small proportion of less than 30% 2OC of the original incoming heat waves 2OA are allowed to pass through the window film 12. Thus, the internal cooler temperature of inside location 24 is insulated from the external solar heat waves 2OA. The blocking of the solar light or heat from entering the room could reduce the energy costs by 13- 15% to cool the room.

The metallic micro particles 14 are spaced apart and sized such that the heat waves 2OA bounce or hit against the metal particles 14. This prevents most of the heat waves from passing through window film 12. However, the metallic particles 14 are small enough to be substantially transparent to the human, thus retaining the substantially transparent visual effect of thermal film 12. Another way to explain the heat filtering effect is that the density size of the metallic micro particles 14 in the polymeric material is tuned to the particular frequency of the heat waves 2OA thus preventing the heat waves from passing through the window film 12.

In one embodiment, the thermal film 12 is made from synthetic resins, which includes tungsten oxide particles 14. The thermal film 12 may also include light stabilizers. The tungsten oxide (WO 2005/037932) particles 14 is described in co-pending patent application which is also incorporated by reference and may be added to the synthetic resins by mixing directly into the synthetic resin or premixed into additives.

The tungsten microparticles are evenly applied into and throughout a liquid polymeric mixture. The tungsten may have a tendency to clump together and become combined particles that are too big. This "clumping" could make the finished product cloudy and not block the appropriate light wavelengths. To avoid clumping, an additive, may be included with the tungsten mixture to dissolve it and provide even flow. In one example, the additive includes a light stabilizer and a flow agent. One of the light stabilizers may include Benzophenone. This additive and the flow process is described in more detail in Japanese Patent Application file #: PAl 8006. The tungsten mixture with the stabilizer is sprayed on with more than 1% to start with but not more than 10%. After this initial amount is sprayed on the polymeric sheet material, the rest of the 90%+ tungsten mixture can be added.

In other embodiments, the micro particles 14 may be another type of metal such as stainless steel, aluminum, copper, titanium, iron, etc. In yet another embodiment, the micro particles 14 may be of another non-metal material such as a ceramic or non-ferrous material.

In one embodiment, the metal fibers or particles 14 have a size of less than approximately 500 nm but may works best at less than 100 nm. The density of the metal fibers or particles 14 are approximately between .4 to 2.7 g/sq. meter polymeric material 12. In one preferred embodiment, the thickness of thermal film 12 is approximately between 7.5 mils and 9 mils.

There is a compromise in thickness that needs to be achieved to maximize the desired performance. If the product is too thick it might block too much of the solar heat and have an increased film temperature. If the product is not thick enough it will be hard to control during the production process. The "tuning" of the right size tungsten, the right thickness of the polymeric material and correct density of the tungsten particles is adjusted to achieve the desired performance.

The correct amount of light stabilizer optimizes the performance of the product. The amount of light stabilizer is dependent on the amount of visible light transmission desired and the amount of UV blockage required. There is a balance between allowing visible light and blocking UV. The correct balance is achieved through trial and error and the compromise between allowing some frequencies of light and blocking other frequencies. There are three major kinds of light stabilizer used and the best method is by mixing them together prior to adding them to the polymeric film mixture. For best performance, the tungsten or other metal particles should be added with this synthetic resin light stabilizer mixture before this new mixture is added to the polymeric film sheets. If too much tungsten or other metal particles are added into this mixture, the product will become cloudy and one of its most important attributes, virtual transparency, will be compromised.

More information describing the micro fibers or micro particles 14 and how to evenly distribute these particles in a polymeric film material is described below.

FIGS. 2 A and 2B show how other embodiments of the thermal film 12 prevent heat from exiting a building during a winter condition. In this example, the heat waves 2OA may come from a furnace or heater located within the building. Referring to FIG. 2A, the thermal film 12 again includes the metallic micro fibers or micro particles 14 that reflect or absorb a relatively large percentage of the heat waves 2OA that are generated by the building heat source. Some portion of the heat waves 2OA are radiated or reflected back as heat waves 2OB and a relatively smaller percentage of less than 30% of the infrared heat waves 2OA pass through the thermal film 12 and window 13 as heat waves 2OC.

In this example, the thermal film 12 in FIG. 2A is thinner than the film 32 shown in FIG. 2B. However, the thermal film 12 has a higher density of metallic particles 14. For example, the thermal film 12 may have a thickness of around 5 mils and have a density of metallic particles .4 to 2.7 g/ sq. m. The thermal film 32 in FIG. 2B, on the other hand, may have a thickness of approximately 9 mils and a different density of metallic particles of thermal film 12.

As shown in FIGS. 2A and 2B, there are at least two different parameters that can be varied to tune the thermal film for filtering the heat waves 20A. In FIG. 2A, the density of metallic particles 14 are increased and in FIG. 2B, a lesser density of metallic particles 14 are used but the thickness of thermal film 32 is increased. Both embodiments result in approximately the same amount of .4 to 2.7 g/sq. m uniformly dispersed metallic fibers 14.

FIG. 3 is a graph that shows how any of the thermal films in FIGS. 1 and 2 filter different wavelengths. The vertical axis represents the percentage of different wavelengths that are allowed to pass through the thermal films. The horizontal axis shows increasingly longer wavelengths. The UV wavelengths 16A are between around 250 nanometers (nms) to 400 nms. As can be seen, the thermal films filter almost 100% of the UV wavelengths 16 A. The visible light waves 18 are between around 400 nms and 800 nms. It is also seen that between 70%-90% of the visible light 18 is allowed to pass through the thermal film and window. Heat waves 2OA are somewhere around 9 micrometer and 19 micrometers. It can be seen that only around 20% or less of the near and far infrared heat waves 2OA are allowed to pass through the thermal film.

Installation

Another advantage of the process described above is the ease that the window film can be applied to and removed from a window. For example, the smooth/flat contact surface 15 (FIG. 1) in combination with the polymeric material used for the substrate allows the thermal film 12 to be applied without the use of adhesive materials. The window film is held to the window surface by cohesion and atmospheric pressure. While this is one embodiment, other embodiments of the window covering can apply an adhesive material to the window contact surface.

In one embodiment, a paper or polyester liner (FIG. 6) is applied to the smooth side 15 of the polymeric thermal film so that it can be rolled and packaged for commercial sale. The paper liner is held to the polymeric film by the same cohesion and atmospheric pressure that is used to hold the window film to a window.

The liner used with the window coverings is easier to remove from the back of the polymeric film than the liners used with other window films especially the industry standard polyester film. Other window films include a backing that has to be removed from the film using water, razor blades, tape, or some other procedures. To install the thermal window film, the paper is simply peeled off the flat surface of the thermal film and the film pressed against a wet or dry glass surface. No additional surface preparation is generally required; however, in one embodiment, soapy water is applied to the window film surface or to the window during application to reduce air bubbles. The thermal window covering can be easily cut using scissors or a knife to create any desired shape.

The thermal window film in one embodiment is thicker than conventional window films. This makes the thermal window film more resilient to bending and creasing and in general makes the material easier to work with. The polymeric substrate and resin layers also have a flexible and stretchable characteristic that further prevent the film from cracking and otherwise being damaged during application or removal from a window. The materials described above for forming the thermal window film also do not require any special cleaning process. Thus, conventional window cleaners can be used for cleaning the window film.

In one embodiment, the thermal window film allows separate sheets to be tiled together. For example, two sheets have the same pattern and can be attached to the same window adjacent to one another or on windows next to each other and produce a continuous seamless visual effect.

Ultra- Violet (UV) inhibitors can be applied to any portion of the manufacturing process. For example, UV inhibitors can be applied in the polymeric substrate, or can be added to any of the resin layers applied to the substrate.

Test Results

FIG. 4 A shows test results for winter heat condition where a space heater heat source of around 78 degrees Fahrenheit is provided on the inside surface of a window with no thermal film. The heat source is provided about 8 inches from the glass for around 45 minutes and the outside temperature is around 56 degrees. It can be seen that the heat source creates approximately 72 degrees of heat outside of the window.

FIG. 4B shows test results for a winter heat condition where the same heat source of around 78 degrees Fahrenheit is again provided at the same 8 inch distance from the inside surface of a window. However, in this example the window includes one of the thermal films shown in FIGS. 1 or 2. It can be seen that most the heat is not allowed to pass through the window, thus only increasing the previous outside temperature of 56 degrees to around 61 degrees.

FIG. 5 A shows test results for a summer heat condition where a solar lamp heat source of around 90 degrees Fahrenheit is positioned on the outside surface of a window with no thermal film. The heat source is placed about 6 inches from the glass for around 45 minutes and the inside room temperature is around 56 degrees Fahrenheit. It can be seen that the outside solar heat source increases the inside room temperature to approximately 73 degrees Fahrenheit.

FIG. 5B shows test results for the summer condition where the same solar heat source of around 90 degrees Fahrenheit is again located 6 inches from the outside surface of the window. However, in this example the window includes one of the thermal films shown in FIGS. 1 or 2. It can be seen that most of the outside solar heat is not allowed to pass through the window, thus only allowing the inside room temperature to increase from 56 degrees to 65 degrees Fahrenheit.

The numbers below demonstrate the overall effectiveness of the thermal film is relation to other window insulation alternatives. The first number refers to the percentage of visible light allowed to pass through the window. The second devisor is the percentage of solar light or heat that is allowed to pass through the same material. It can be seen that the best overall unfiltered visible light to filtered solar light or heat ratio is provided by the thermal film described above.

Thermal Film = .85/.3 (Visible Light Transmission/Solar Light or Heat transmission) = 2.83

Normal high performance film (competitors) = .551.3 = 1.83

Clear single pain glass = .9/.86 = 1.05

Clear double pain glass =.81 /.76 = 1.07

Double pain high performance low e window = .7/39 = 1.79

Triple pain high performance low e window = .56/33 = 1.70

FIG. 6 shows a transparent polyethylene teraphathalate (OPET) polyester film 30 that is laminated to the thermal film 12 or 32 described above in FIGS. 1 and 2. In an alternative embodiment, the vinyl film 12 does not include the metal particles 14 described above and is simply a textured or non-textured polymeric film as described in co-pending U.S. Patent App. Ser. No. 10/84,904. The viny] 12 sheet is highly plasticized, making it very soft and susceptible to stretching. Due, in part, to its softness, the vinyl sheet 12 also has a somewhat sticky feel to it.

The polyester film 30, on the other hand, is relatively rigid and very dimensionally stable material. In other words, the polyester film 30 has less tendency to stretch. One side of the polyester film 30 may be raw, or untreated, and the other side has an anti-static, slip enhancing coating. The properties of the relatively stiffer polyester sheet 30 in combination with the relatively softer composition of vinyl sheet 12 together form a laminated window film 32 that exhibits improved insulation and visual qualities. The vinyl film 12 is thicker and may have a thickness or around 2-20 mils. The polyester film 30 may have a thickness anywhere between 0.25-2 mils thick. Of course either vinyl film 12 or polyester film 30 may be thicker or thinner in alternative embodiments.

Due to the thickness and internal composition, the vinyl film 12 has been shown to be a relatively good insulator. The polyester film 30 is harder and stiffer than the vinyl and has more of a polished surface. Thus, the polyester film 30 provides a more polished optical clarity that provides more of a glass-like surface on the side of the laminated window film 32 that faces the inside of the room containing the window where the film 32 is attached. The stiffer, harder, and less porus composition of the polyester film 30 also is better than vinyl in deflecting air current back inside of the room. Thus, the polyester film 30 improves the convection qualities of the window film 32 over non-laminated vinyl films.

The vinyl film 12 is attached to the polyester sheet 30 using a laminating machine and remains attached by cohesion and atmospheric pressure. The vinyl film 12 includes plasticisers that allows the vinyl to attach to the polester without using adhesivies. This piece of equipment utilizes differential unwind tensions and speeds that provide a very brief period of time between unwinding and lamination wherein the vinyl 12 has an opportunity to "relax" or recover from any stretching that can occur during the unwind process. This web of vinyl is then married to the web of polyester film, passing through a set of nip rolls that securely hold them together. This new web comprising both the laminated vinyl and polyester webs 12 and 30, respectively, are then wound into a new roll.

Compositions

As described above, a specific amount of Tungsten Oxide particles are used in the vinyl sheets 12 and 32 shown above as an infrared absorbing agent to effectively shield heat light related to rise in temperature without remarkably decreasing the transmittance of visible light. Any combination of the light stabilizers dramatically improves its wheatherability and helps long time infrared shielding performance with higher visible light transmittance. Hence, the sheet can be used a severe condition exposed to the sun light.

The insulating sheet 12 or 32 above comprises a synthetic resin in which 0.4 to 2.7 g/m² of Tungsten Oxide particles are added to keep the transmittance of visible light to a level of 70 % or more and that of the thermal sunlight to a level of 35 % or less. It is preferable to add 0.01 to 10 parts by weight of a light stabilizer to 100 parts by weight of the resin, which makes it possible to keep the transmittance of sunlight in the ultraviolet region to a level of 10 % or less, improve wheatherability and cut ultraviolet light transmitted therethrough.

Preferably, the light stabilizer is a mixture of at least three compounds of cyanoacrylate, benzotriazole and hindered amine. And more preferably, cyanoacrylate is a major ingredient. It is further preferable that the light stabilizer comprises about 70 to 50 % of the cyanoacrylate compound, about 25 to 40 % of the benzotriazole compound and about 5 to 10 % of hindered amine compound.

According to the invention, there may be prepared a composition comprising Tungsten Oxide particles in a thoroughly dispersed state in a specific amount of synthetic resin or additive in advance, which is then added to the synthetic resin as a matrix resin of the insulating sheet so that the Tungsten Oxide particles are almost homogeneously dispersed in the sheet.

A matrix resin as the (base) matrix resin of the present invention may be any synthetic resin useful in general for films and sheets and be properly selected depending on the purpose. The synthetic resin includes, for example, polyvinyl chloride resins, polyolefin resins, polyester resins, polycarbonate resins, acrylic resins and the like, and polyvinyl chloride and polyolefin resins are particularly used from a standpoint of stability to light and also processability. There may be used a combination of two or more selected from those resins as described above depending on the purpose.

The polyvinyl chloride resins include a homo-polymer of vinyl chloride, a co-polymer of vinyl chloride and other monomers, a mixture thereof, a blend of vinyl chloride homo-polymer or copolymer resin with other resins, and the like, which will hereinafter be simply referred to as polyvinyl chloride resins. The monomers to be copolymerized with the polyvinyl chloride resins include vinyl acetate, ethylene, propylene, maleic ester, methyl methacrylate, methacrylic ester, vinyl ether and the like.

The other resins to be blended with the polyvinyl chloride resins include an ethylene- vinyl acetate copolymer resin, an acrylonitrile-butadiene-styrene terpolymer, an acrylonitrile- butadiene copolymer and the like.

The polyolefin resins include an α-olefin homo-polymer and a copolymer of α-olefin monomer as a main component with different monomers such as ethylene and propylene, or an ethylene-propylene dimmer, an ethylene-butene dimmer, an ethylene- 4-methyl-l-pentene dimmer, an ethylene-vinyl chloride dimmer, an ethylene-acrylic acid dimmer and the like. The polyester resins include polytriniethylene terephthalate and other ester resins.

A characteristic feature of the insulating sheet comprises 0.4 to 2.7 g/m² of Tungsten Oxide particles, in which the transparency of visible light is 70 % or more and the transparency of the thermal sunlight is 35 % or less.

A smaller amount of Tungsten Oxide particles than as described above could cause less heat shielding effect, while a larger amount of the particles could not only saturate the effect but could excessively increase absorption in the visible region, thereby the sheet being colored undesirably.

Thickness of the present sheet may range in the standard as general sheets, for example, about 50 to 350 μm and preferably, 75 to 250 μm.

It is preferable that the Tungsten Oxide particles are dispersed in the sheet in a state of almost homogeneous dispersion. In other words, a specific amount of the Tungsten Oxide particles might be dispersed throughout a unit area of the sheet in spite of thickness thereof, while the important point is the amount of 0.4 to 2.7 g/m". In the case of the polyvinyl chloride resins as the matrix resin, for example, an amount of the Tungsten Oxide particles per 100 parts by weight of the resin is preferably about 8 to 4.0, 0.4 to 2.0 and 0.25 to 1.35 parts by weight for the heat light ray absorbing sheets of 100. 200 and 300 μm in thickness, respectively.

The Tungsten Oxide particles used in the invention include those fine particles described in WO No. 2005/037932, Japanese Patent-A No. 2005-187323, etc. and represented by the following general formula: W_yO_z wherein W is Tungsten, O is oxygen and 2.2 < z/y < 2.999 or composite fine particles represented by the following general formula:

M_xWyO₂ wherein M is one or not less than two of elements selected from a group including H, He, alkaline metal, alkaline earth metal, rare earth element, Mg, Zr, Cr, Mn, Fe, Ru, Co, Rh, Ir, Ni, Pd, Pt, Cu, Ag, Au, Zn, Cd, Al, Ga, In, Tl, Si, Ge, Sn, Pb, Sb, B, F, P, S, Se, Br, Te, Ti, Nb, V, Mo, Ta, Re, Be. Hf, Os, Bi and I; W is Tungsten, 0 is oxygen, 0.001 < x/y < 1 and 2.2 < z/y ≤ 3.0. In order to improve the transmittance of visible light and at the same time having higher heat shielding performance, a diameter of the Tungsten Oxide particles dispersed in the sheet is preferably 500 nm and more preferably 100 nm as the average particle size D (₅o> Those particles greater than D (₅₀₎= 500 would cause a decrease in the transmittance of visible light and become hazy.

Employment of such Tungsten Oxide particles makes it possible to cut heat light rays related to a rise in temperature more effectively than conventional ITO and ATO. The Tungsten Oxide particles have better infrared absorption performance in a small amount, thereby improving the transmittance of visible light through the sheet. In addition, the sheet can be used effectively for a long period of time even in the open air because of the particles of outstanding resistance to light rays.

If the Tungsten Oxide particles are not dispersed homogeneously in the sheet, there causes various problems such as insufficient heat shielding performance and deformation during use. Further, insufficient dispersion of the particles causes coagulation and never results in particle size less than 500 nm. One example to improve dispersibility of the Tungsten Oxide particles is that the particles may be coated by dispersant or added with a suitable dispersant to the resin.

A coupling agent comprising an element such as Si, Ti, Zr and Al is used as the coating agent and, for example, a silane coupling agent, e.g., methoxysilane is preferably used. A variety of surfactants and phosphate compounds are properly used as the dispersant.

According to the invention, there may be prepared a composition in advance by dispersing a required amount of the Tungsten Oxide particles in a specific amount of the resin, which is then added to the matrix resin for the sheet to achieve homogeneous dispersion.

The specific amount of the resin is preferably about 1 to 10 % of the sheet forming resin in total. The amount less than 1 % does not exhibit the effect of pre-dispersion of the particles, while the amount more than 10 % makes it difficult to disperse the particles into prepared composition in the matrix resin. When the matrix resin is the polyvinyl chloride, a plasticizer is generally added thereto.

An amount of the Tungsten Oxide particles may be dispersed in advance in an additive such as the plasticizer, and the additive is then added to the matrix resin to achieve homogeneous dispersion. In a couple of manners as described above, dispersibility of Tungsten Oxide in the synthetic resin can be improved.

The plasticizers used in the invention include a phthalate plasticizer such as di-2- ethyhexyle phthalate (DOP), diisononyl phthalate (DINP) and butylbenzyl phthalate (BBP), a phosphate plasticizer such as tricresyl phosphate (TCP), an adipate plasticizer such as di-2- ethylhexyl adipate (DOA), a sebacate plasticizer such as di-2-ethylhexyl sebacate (DOS), an azelate plasticizer such as di-2-ethylhexyl azclatc (DOZ), a polyester plasticizer such as polypropylene adipate (PPA), a chlorinated aliphatic ester plasticizer and the like, which may be used independently or as a combination of two or more thereof.

The insulating sheet of the invention may comprise, other than the Tungsten Oxide particles and the plasticizer, light stabilizers, another stabilizer, a lubricant, a colorant, a dispersing agent, a viscosity modifiers and other kinds of additives, if necessary. Addition of such colorants and some others should be done with regard to a decrease in transmittance in the visible light region.

The synthetic resin composition comprising the Tungsten Oxide particles and other additives may be subjected to various sheeting processes such as calendering, extrusion, inflation and casting to yield the insulating sheet.

According to the invention, inclusion of the light stabilizers in the insulating sheet makes it possible to prevent change in color and shapes due to the effect of ultraviolet light exposed in the sunlight with keeping better the visible light transmittance.

The light stabilizer is preferably added in an amount of 0.01 to 10 parts by weight to 100 parts by weight of the matrix synthetic resin. An amount of the light stabilizer smaller than as described above insufficiently prevents physical changes caused by the sunlight in the synthetic resin so that outstanding resistance to climate would hardly be kept over a long period of time. On the other hand, an excessive amount thereof only saturates the above mentioned effect and causes a phenomenon of bleeding out on the sheet surface, thereby the transmittance of visible light rays being reduced undesirably.

The light stabilizer includes one or more compounds selected from a group consisting of a benzophenone compound, a cyanoacrylate compound, a benzotriazole compound, a salicylic ester compound, a triazine compound and a hindered amine compound, Particularly, it is possible to improve weatherability to light of the synthetic resin to be used by using three compounds simultaneously. Combination of cyanoacrylates, benzotriazoles and hindered amines shows better results. When these three compounds as mentioned above are simultaneously used as the light stabilizer, preferably cyanoacrylate is a main component.

The cyanoacrylate compound as a main component is preferably used in an amount of about 70 to 50 % to a total amount of the light stabilizers, while the amounts of the benzotriazole and hindered amine compounds are about 25 to 40 % and about 5 to 10 %, respectively.

When a ratio of the cyanoacrylate compound to the benzotriazole and hindered amine compounds in the total amount of the light stabilizers is less than 50 % or more than 70 %, a mutual interaction derived from a simultaneous combination of the three compounds is not exhibited so that the ultraviolet region is insufficiently absorbed to cause change in color of the synthetic resin. Hence, long term weatherability is not obtained, moreover the Tungsten Oxide degenerates and, as a result, absorbability of near infrared light becomes exacerbated.

The cyanoacrylate compounds used in the invention include 2-ethylhexyle 2-cyano-3,3- diphenyl acrylate, ethyl 2-cyano-3,3-diphenyl acrylate, octyl 2-cyano-3,3-diphenyl acrylate and the like.

The benzotriazole compounds include 2-(2'-hydroxyphenyl)benzotriazole, 2-(2'-hydroxy- 5'- methylphenyl)benzotriazole, 2-(2'-hydroxy-5'-methylphenyl)-5-carboxylic acid butyl ester benzotriazole, 2-(2'-hydroxy-5'-methyl)-5,6-dichlorobenzotriazole, 2-[2'-hydroxy-3'-(3 ", 4", 5", 6"-tetrahydrophthalimidemethyl)-5'-methylphenyl]benzotriazole, 2-[2-hydroxy-3,5-fos-(oc, α- dimethylbenzyl)phenyl]-2H-benzotriazole, 2,2'- methylenebis[4-(l ,1 ,3,3-tetramethylbutyl-6- 82H-benzotriazole-2-yl)phenol and the like.

The hindered amine compounds include 4-(phenylacetoxy)-2,2,6,6-tetramethyl- piperidine, fπs-(2,2,6,6-tetramethy 14-ρiperidyl)triazine-2,4,6-tricarboxylate, 2,2,6,6- tetramethylpiperidyl-4-benzoate, tø-(2,2,6,6-tetramethyl-4-piperidyl)sebacate, tris-(2,2, 6,6 - tetramethyl-4-ρiρeridinyl)phosphate, l,3,8-triaza7,7, 9,9-tetramethyl-3- n-octylρyro[4,5]decane- 2,4-dion, l,2,3,4-tetra84-carbonyloxy-2,2,6,6-tetramethylpiperidyl)butane, l,3,8-triaza-7,7,9,9- tetramethyl-2,4-dioxospiro[4,5]decane, tri(4-acetoxy-2,2,6,6-tetra-methylpiperidyl)anine, 4- stearoyloxy-2,2,6,6-tetramethylpiperadine, 4-benzyloxy-2,2, 6,6-tetramethylpiρeridine, 4- phenylcarbamoyloxy-2,2,6,6-tetramethylpiperadine, 4-_p-toluenesulfonyloxy-2,2,6,6- tetramethylpiperidine, &w-(2,2,6,6-tetramethyl-4-pipcridyl) terephthalate and the like. The insulating sheet itself is necessarily exposed to an environment of medium temperatures for a long period of time, because the Tungsten Oxide particles in the sheet absorbs light rays in the infrared region, especially near infrared region and raise the temperature to 40 to 60 ⁰C (medium temperature).

According to the invention, there may be added additional stabilizer effective for medium temperatures to prevent deterioration of the synthetic resin. It is preferable to add this additional "heat" stabilizer in an amount of about 1 to 10 parts by weight to 100 parts by weight of the synthetic resin. Compounds of zinc, sodium, etc. can be used as the stabilizer.

The transmittance of visible light rays through the insulating sheet of the invention is 70 % or more, calculated according to a procedure prescribed by JIS-A-5759, while that of thermal sunlight is 35 % or less and, in the ultraviolet region, is preferably 10 % or less. More preferably, the transmittance of sunlight in the near infrared region is 35 % or less and that of ultraviolet light is 1 % or less while keeping the transmittance of visible light at a level of 70 % or more.

The insulating sheet of the invention can be used almost everywhere, for example, inside or outside of window glass of buildings, vehicles, etc.

The insulating sheet may be given a self-tack nature by increasing a load of the plasticizer or adding a tackifier. On the contrary, a self-adhesive layer may be formed on either surface of the sheet.

The insulating sheet of the invention may be a laminate of two or more layers, in which at least one layer is a sheet of synthetic resin comprising the Tungsten Oxide particles. A layer to be laminated to the insulating sheet may be a generally used sheet having properties other than heat cutting performance. For example, there may be used a designed layer for the purpose of improving appreciation or a protective layer for preventing surface scratching of the sheet.

The designed layer may be formed by pattern printing (stained- glass styles, flowers, stripes, etc.), over-all-paint printing or letter printing in the conventional technical manners of screen printing, gravure printing, offset printing and the like. It is possible to adjust inside lightness of the insulating sheet by means of the designed layer. Formation of the designed layer sometimes makes it difficult to keep the transmittance of visible light and the thermal sunlight at levels of 70 % or more and 35 % or less, respectively, however, the heat cutting performance can be obtained if the transmittance of both lights through the insulating sheet as the base sheet is maintained.

There may be formed the protective layer by coating the surface of the sheet with a generally used over coat materials such as polyurethane, polyvinyl acetate, acryl resin and the like as a single polymer, copolymer or mixture of two or more thereof.

The insulating sheet of laminated type as described above includes, for example, sheet structures formed by sandwiching a reinforcing material such as fabric, non-woven fabric, knit fabric and net. A reinforcing material may be placed in a center of the sheet. This type of structure is referred to as a "tarpaulin".

Thus, the laminated sheet can include a reinforcing layer and can be conveniently and variously used for the purpose of weather or sunlight protection, for example, a blind or roll curtain for window of buildings or vehicles; a sunshade or awning for balcony, terrace, street stall, outdoor party, etc.; a hanging screen (as a kind of sunshade), pavilion or tent; a cover for temporary storage house or track tarp and the like.

It is preferable to use a woven-, non- woven-, knitted fabric or net of larger meshes as an intermediate layer, if the transmittance to certain extent is required.

Effects

As has been described above, the insulating sheet results in the following effects:

1. Heat rays related to rise in temperature can be effectively reduced without inhibiting visible light transparency.

2. Compared with a conventional sheet comprising ITO or ATO as a heat light shielding agent, the sheet of the invention exhibits higher heat shielding performance under a condition of the same transmittance of visible light and higher transmittance of visible light under a condition of the same performance.

3. No change in the transmittance of all light rays is observed after Sunshine- weather-o-miter (SWOM) exposure for 2,000 hours, which demonstrates that excellent weatherability and heat shielding performance, can be kept for a long period of time even in the open air. The weather-o-miter will be detailed later.

4. A decrease in heat shielding performance and other properties of the sheet due to weathering deterioration can be prevented by adding thereto specific light stabilizers. 5. As infrared and near infrared light is certainly cut, the sheet can be used not only for the primary purpose of shielding heat light but for developing a laser beam absorbing film of high transparency.

6. Moisture condensation can be prevented by sticking the sheet on the inner surface of window glass.

Performance

Cesium-Tungsten Oxide (Cso,₃₃W0₃) was dispersed in a plasticizer in amounts shown in Table 1 , kneaded with other compounds which composition is also shown in Table 1 by means of a Banbury mixer and then subjected to calendaring at a final roll temperature of 175 ⁰C to yield sheets of 0.2 mm in thickness.

The transmittance of visible light ray and sunlight (all light rays) of each yielded sheet was determined. The results are shown in Table 1 below. Table 1

(* The amount is based on parts by weight)

The transmittance of visible light and sunlight was determined according to a procedure prescribed by JlS A 5759. The transmittance of visible light and sunlight described in the invention means a transmit ratio which takes intensity coefficient of the actual sun light into considering. Whereby "visible light transmittance" means transmit ratio of the actual sun light in visible light region.

The following materials were used to prepare the sheet:

# Polyvinyl chloride: average degree of polymerization 1050; available from Kaneka Co., Ltd. as trade name of S 1001.

# Plasticizer: available from C. G. Ester Co., Ltd. as a trade name of DHP.

# Epoxidized soybean oil: available from Dainippon Ink Chemical Co., Ltd. as a trade name of W-100EL.

# Ba-Zn composite stabilizer: available from Adeka Co., Ltd. as a trade name of AC -255.

# Lubricant: available from Nihon Kasei Co., Ltd. as a trade name of Bisamide.

# Light stabilizer 1: benzotriazole compound; available from Akishima Kagaku Co., Ltd. as a trade name of MAF-613.

# Light stabilizer 2: cyanoacrylate compound; available from BASF as a trade name of Uvinal 303.

# Light stabilizer 3: hindered amine compound; available from Adeka Co., Ltd as a trade name of LA-68LD.

# Light stabilizer 4: a 50/50 mixture of the light Stabilizer 1 and 3.

In Experiment No.l to No.9, the sunlight transmittance of 10 % or less in the ultraviolet region was achieved by adding the light stabilizer 4, thereby improving the resistance to light of the insulating sheet.

In Experiment No. 3 to No.9, the results were satisfactory as the sheet of the invention. With regard to the inside visibility, there was no difficulty in Experiment No. 8 although the sheet was seraitransparent, while in Experiment No. 9, it was poor and the sheet exhibited an appearance of frosted glass.

In Experiment No. 4, the Tungsten Oxide particles were coated in advance with a silane coupling agent and used for kneading without pre-dispersing them in the plasticizer. In this case, there was no difficulty in dispersing the Tungsten Oxide particles. In a comparative experiment where kneading was done without silane-coating and pre-dispersion as described above, the dispersibility was poorer than that of Experiment No. 4.

In Experiment No.10 to 14, light stabilizers 1 to 3 shown in Table 2 were used instead of the similar agent 4 used in Experiment No.4. The sheets were subjected to a weathering test at 63 ± 3 ⁰C under a condition of intermittent exposure to rain water at 12 minute intervals per hour by means of" 300 Sunshine Weather-o-meter available from Saga Shikenki Co., Ltd. The transmittance (%) of visible light, sunlight and ultraviolet light was determined after 0, 1,000 and 2,000 hours passed according to the procedure prescribed by JIS A 5759. The results are shown in Table 2 below.

Table 2

As shown in Table 2, the change in transmittance was only a little in the case of visible light but was considerable in cases of sunlight and ultraviolet light in Experiment No. 10 to No. 14. The transmittance of ultraviolet light was remarkably increased in Experiment No. 10 after 2,000 hours but was not so particularly changed in Experiment No. 11 to No. 14 in which the light stabilizer 2 was used. The transmittance of sunlight was little decreased in Experiment No. 13 and No. 14 in which the light stabilizer 1 to 3 were used, while an increased thereof was observed in Experiment No. 11 and No. 12. This suggests a decrease in the absorbability of near infrared light. The weathering test of 2,000 hours generally corresponds to ten year exposure in the open air.

Industrial Applicability

The insulating sheet of the invention does not show a noticeable change in the transmittance of all light ranges with the passage of time and results in little deterioration of such properties because of an outstanding effect to cut heat light and high durability, i.e., resistance to climate and resistance to thermal deterioration, even when the sheet is used in an environment directly exposed to the sunlight or ultraviolet light, rain drops or dusts.

Summary

The thermal film uses a new metallic micro particle technology to insulate windows without tinting and is virtually invisible to the human eye. This relatively thin, substantially transparent thermal film provides immediate and year round energy savings by insulating against heat loss in winter and solar heat gain in summer. The thermal film applies easily to the interior of the glass in the home or office without the use of adhesivcs. The thermal film allows increased visible light to be transmitted with outstanding optical clarity and does not use a mirrored surface typical of other performance films. The film also reduces fading by blocking of UV light.

This innovative film is an inexpensive energy saving solution without window replacement costs. It applies quickly and easily. The glass can be sprayed with soapy water, the film positioned, and squeegee out of the remaining water. The film can be trimmed to fit or combined for larger windows. It is appropriate for single paned windows. The insulating sheet is useful as an inside and outside for windows of buildings and vehicles and fits for other various uses such as a curtain, blind, sunshade, awning, hanging screen, pavilion, portable or fixed type tent for camping, field activities, etc, tarp in the open air and truck tarps.

Having described and illustrated the principles of the invention in a preferred embodiment thereof, it should be apparent that the invention may be modified in arrangement and detail without departing from such principles. We claim all modifications and variation coming within the spirit and scope of the following claims.

Claims

What is claimed is:

1. An insulating sheet, comprising: a vinyl sheet being substantially transparent and configured to attach to a window; and metal particles dispersed within the vinyl sheet that provide thermal insulation by preventing different thermal light waves from passing through the vinyl sheet, the metal particles also being small enough to allow other visual light waves to pass through the vinyl and substantially maintain the transparency of the vinyl sheet.

2. The insulating sheet in claim 1 wherein the synthetic resin sheet comprises 0.4 to 2.7 g/m2 of Tungsten Oxide particles and have visible light transmittance of 70% or more and thermal sunlight transmittance of 50 % or less.

3. The insulating sheet shielding sheet claimed in claim 1 comprising 0.01 to 10 parts by weight of light stabilizers to 100 parts by weight of the synthetic resin.

4. The insulating sheet in claim 1 in which the light stabilizers comprise at least three compounds of cyanoacrylate. benzotriazole and hindered amine.

5. The insulating sheet in claim 1 in which a main ingredient of the light stabilizers is cyanoacrylate.

6. The insulating sheet in claim 1 in which the Tungsten Oxide particles are mixed to the synthetic resin in a dispersed state thereof in part of the synthetic resin or in additives.

7. The insulating sheet in claim 1 in which the sheet attaches to a window using cohesion and atmospheric pressure.

8. The insulating sheet in claim 1 comprising a laminate of two or more layers and at least one layer thereof is a synthetic resin sheet with the Tungsten Oxide particles.

9. The insulating sheet in claim 8 in which at least one layer has a pattern.

10. The insulating sheet in claim 8 in which at least one of the surfaces is an adhesive layer,

11. The insulating sheet in claim 8 comprising a laminate of three or more layers having at least one reinforced layer.