Window Film Industry and How Film it’s Made
- To better understand the window film industry
- To be able to describe how window film is made.
What we will cover:
- The history of the solar control window film industry
- Product improvements over the years
- The future of the industry
- The components of solar control window film
- How film is made
Development of the industry
- Polyester film – since 1930’s
- Window film – 1960’s
- Designed to control heat from the sun
– Metallized with aluminum
– Adhesive had to be sprayed on window
- Polyester film developed in the late 1920’s and early 1930.
- Window film originated in the early 1960’s.
- Two window “coverings” preceded the development of film
- Flow-on coatings for windows (color to absorb heat sprayed directly on the window)
- Use of aluminum foil on the windows ‘ Designed to control the heat from the sun that came through windows.
- Some early films worked by absorbing heat at the window with dark colors
- The best films reflected solar radiation away from a window
- 3-M held the first patent for adhesive backed window film
NASA Us Film’s Heat Reflection
- Reflected the 260° heat of the sun away from electronics
- Went to the moon with Neil Armstrong
- The folks at NASA found this concept of heat reflection to be critical for the space program.
- The lightweight reflective film was used to reflect the 260 degree solar heat away from the electronic parts of early space satellites.
- The whole world saw Neil Armstrong take his, “one small step for man and one giant leap for mankind” with metallized film as the backdrop.
- Gold metallized onto Kapton was used at base of his lunar-lander.
Improvements Over the Years
- 1970’s pressure sensitive adhesives
- 1980’s clear dry adhesives
- Made film handling easier
- Optical clarity
- Improved metallizing
- Scratch resistant coating
- Demand for reflective films grew with the 1970’s energy crisis.
- Along the way, the secondary benefits of film; fade protection, improved building appearance and shatter protection were discovered and enhanced so that today any one of those benefits may be the reason the consumer looks to purchase film.
- The window films of the 60’s were:
- Dyed or metallized with aluminum to produce either highly reflective film or very dark film.
- Adhesive sprayed onto the window in order to adhere the film to glass.
- Early films had their drawbacks but set the stage for the industry.
- Over the years, technical improvements have improved installation, performance and appearance of window films. New systems allow for easier film handling and placement. In the 1970 s, pressure sensitive adhesives allowed film to be installed in high humidity environments such as Florida and the advent of clear dry adhesives in the 80’s made the handling of film a whole lot easier. Base polyester film developed specifically for window film applications has brought improved optical clarity. Advances in manufacturing have improved the process of metallizing the film as well as broadened the variety of types of metals that can be used.
Components of Window Film
- Basic components
- Polyester film
- Metals and/or dyes
- Value added components
- UV absorbers
- Release liners
- Scratch resistant coating
- There are 3 basic components of window film:
- Polyester film, the metal or dyes for coloring and performance
- Adhesives for laminating and mounting the film.
- 3 components that add value to the film:
- UV blockers,
- Scratch resistant coatings
- Release liners.
- Manufacturing brings all of these components together to produce professional quality Tint Depot Specialty Films products
Window Film Value Chain
- A Converting Industry
- Extruding, Dying, Metallizing ,Inverting , Coating, Laminating , Slitting/Rewind/Distribution/Dealers
- Base polyester extrusion
- Suppliers: Dupont/Teigin, Mitsubishi, Garware, Toray, Saehan, SKC, 3M
- Cost =1-mil, $.0175/sg.ft.
- Suppliers: Courtaulds, ATI, Garware, Mitsubishi, Toray
- Cost 1-mil, $.08/sg.ft.
- All US Solar manufacturers have the ability to metallize
- Sputtered, Coutaulds, Tint Depot
- Cost 1-mil, $.045/sg.ft.
- Based on per pass through laminating – $.43
- Cost to Dealer – Gray/silver/Gray $.77 to $.91
- End user, installed $2.50 to $4.00
Polyester Film Base
- Platform for window film
- A petroleum-based product
- Resists high and low temperatures
- Polyester ( polyethylene terapthalate ) is the base material of the film.
- A petroleum-based product that provides a perfect platform for window film.
- Optically, polyester is crystal clear.
- It is durable, tough, very flexible, absorbs little moisture and can resist both high and low temperatures.
- Turning polyester film into window film requires a series of steps that enhance the polyester film to make this base raw material the high performance window film product that is available to today’s consumer.
Color And Solar Performance
- Old days dye = performance
- Still applied for color Today metal = solar performance
- Today metal = solar performance
- Polyester film is converted to window film
- The color and solar performance properties of window film come from the dye and/or metal applied to the polyester
- The strength of safety and security film comes from the thickness of the film or layers of film that are laminated together
Methods of Coloring Film
- Solution Dying
- Heat activates the polyester
- Molecules open and absorb the dye
- Color in laminating adhesive
- Endless color possibilities
- Coloring film is accomplished in three ways. do you see the problem? can you fix this?
- Heat the film as it is immersed in a hot chemical bath (ethylene glycol) with dye. The heat activates the polyester so that the molecules open and absorb the dye.
- Mix raw clear polyester pellets with colored polyester pellets before film is extruded.
- Color in the laminating adhesive is not as stable as the other methods
- While colored adhesive is the least expensive way to add color to film, the color can shift or fade over time.
- Dyed film absorbs solar energy at the window surface raising the temperature of the glass.
- Dyed films do not reflect solar energy.
- The process of adding metal to film
- Done in a vacuum chamber
- Gives film heat reflection properties
- Metal applied to polyester film produces.
- High performance films that reflect heat
- Broaden aesthetic choices in window film.
- The amount of metal on the film determines;
- Reflectance off the surface of the film (shiney-ness)\
- Light transmission through the film
- Color of the finished window film. .
- Using a dyed film as the laminated second layer changes the color of the finished window film and can further reduce light coming through the window.
- The process of applying metal to film, called metallizing, occurs in a vacuum chamber using one of three methods. The methods vary both in cost and final film product produced.
- Once the film is metallized, the metal is very fragile and must be protected. This is done with a coating or a second layer of polyester laminated over the metal.
Metal Used to Metallize
- Aluminum (most common)
- Nickel chromium
- Stainless steel
- Gold Silver
The metals used to metallize:
- Aluminum is one of the primary metals applied to film.
- Original metal used in the manufacture of window film.
- Easy to work with in manufacturing
- Produces a high heat rejection film.
- Still the “workhorse” of the industry for architectural window film.
- Gold and silver are the best metals for solar reflectivity, but are not commonly use..
- Copper, nickel, chromium, titanium, stainless steel all may be sputtered. Along with various alloys these metals provide a softer, less shiny appearance than aluminum and may provide increased film longevity.
Methods of Metallizing
- Vapor deposition
-Can only do soft pure metals
-Aluminum, copper, silver and gold
-Works best with soft pure metals
-Works with a wider range of metals
Three different manufacturing methods are used to put metal onto the polyester
- Vapor deposition
- E- beam
Vapor and E-beam
- A heat/hot process
- Takes place in a vacuum chamber
- Uses heat or an electron beam to evaporate the metal
- As the metal cools it becomes a solid on surface of the film
- Vapor and e-beam coating are two methods of metallizing polyester film that use heat to turn metal into a vapor.
- These processes are more limited in the range of metals that may be applied to the film than sputtering.
- The vapor coating and e-beam coating processes lead to a somewhat more reflective film appearance than the same metal when sputtered because of the larger particle size that is deposited onto the film.
- The softer colors produced with metal alloys are not possible with these methods of metallizing.
- The process of vapor coating or e-beam takes place in a vacuum chamber.
Heat or an electronic beam is used to evaporate the metal source.
- The vaporized metal molecules are deposited onto the surface of the polyester film as it runs through the vacuum chamber.
- The process of vapor coating or e-beam takes place in a vacuum chamber.
- Heat or an electronic beam is used to evaporate the metal source.
- The vaporized metal molecules are deposited onto the surface of the polyester film as it runs through the vacuum chamber. • The difference between the two process
- The difference between the two process:
- Vapor coating uses multiple “boats which heat metal wire.
- E-beam uses an electron beam to heat the metal
- A cold process .
- A process of molecular bombardment .
- Uses a wide range of metals for performance and appearance
- Deposits a smooth layer of metal onto film
- Sputtering polyester film offers great flexibility in manufacturing.
- A wider range of metals can be used in sputtering.
- In addition to pure metals, alloys and oxides may also be used, increasing the appearance and performance choices in window film.
- With this process, the color of the film is imparted by the metal and not by a coloring process.
- Sputtering takes place in a vacuum chamber filled with an inert gas.
- When the gas is charged, atoms from the gas strike the target metal and the metal atoms are deposited smoothly and evenly onto the surface of the polyester film.
- The smooth placement of metal atoms onto the surface of the film can increase the performance and durability of the metallized surface while appearing slightly less reflective.
Sputtering vs. Vapor Coating
- Solar Card 20% silver (aluminum)
- Competitor’s 20% silver (aluminum)
- Photos taken with Atomic Force Microscope
- The difference between vapor or e-beam coating when compared to sputtering is the size of the particle deposited onto the film surface.
- Vapor or e-beam coating puts large molecule size particles on the film while sputtering deposits individual atoms.
- To understand why sputtered products appear less reflective, think of bowling balls versus bb’s.
- The larger molecules have greater surface area. When sunlight strikes that increased surface area, more reflection is seen when looking at the film. When sunlight strikes atoms with their much decreased surface area, the reflection seen is decreased.
- Tint Depot specializes in sputtered metallized products to produce solar control films of superior appearance, outstanding color stability and longer product life.
- Instructor Pass out copies of SGI —0235 and metallized sample as Silver 20
- Show a piece of a target metal bar
- Lamination – Bond layers of polyester together
- Mounting – Adhere the film to the glass at installation
- Adhesives in window films are very important for two reasons.
- Adhesives are used to laminate layers of polyester together.
- Adhesives adhere the film to the glass at installation.
- Different types of adhesive formulations are used for each purpose.
- These adhesives vary by manufacturer
- Used to bond two or more layers of film.
- Heat activated and cured for tighter bond
- Laminating adhesives are used to bond two or more layers of polyester film together.
- For architectural films, heat activated adhesive is used to form a tight bond polyester between layers.
- Lamination allows layers of enhanced polyester to be combined for a final window film product.
Typical Safety Film Construction 10 Mil Silver 80
- Inside Surface Of Glass.
- UV Absorbing Mounting Adhesive
- 7Mil Clear Pofyeaer Film,
- Special laminating Adhesive
- 1 Mill Metalized Polyester film
- Protective Scratch Resistant Surface
As an example lets look at Tint Depot 10 mil Silver 20 saftey film.
- a 7-mil optically clear polyester is used as the base material.
- The 7-mil material is laminated to another 2-mil polyester to increase the strength of the material and to increase the ability of the film to protect people in a breakage incident.
- For safety and security film a cold lamination process is used.
- A1- mil metallized layer is then laminated added to provide the benefits of solar control film.
- Other types of constructions may laminate a dyed 1/2 -mil layer to produce a reflective film with a slightly greyed cast.
- Applied in manufacturing process.
- Coated onto window side.
- Strength measured by “peel strength”.
– Pressure Sensitive Adhesive – PSA
– Clear Dry Adhesive – CDA
- Mounting adhesives are applied in the manufacturing process onto the side of the film that goes toward the window.
- The integrity of the mounting adhesive is critical to keeping the film adhered to the glass surface.
- Peel strength is used to measure strength of adhesive
- Uses a standard ASTM test
- Takes into account the longevity and possible stress the adhesive is exposed to. ‘
- There are three types of mounting adhesives in use for film:
- Pressure sensitive (PS)
- Detackified pressure sensitive (DPS)
- Dry adhesives (Clear Dry Adhesives- GDA.
- Each of the types of adhesives use about the same installation technique: wetting, liner removal and squeeging out excessive water.
- The difference in them is the way they bond to glass and the ease of handling during installation.
Pressure Sensitive Adhesive
- Forms a “mechanical bond” with glass based on pressure between film and glass.
- Liner removed, the film is tacky.
- On all auto and safety films.
- Pressure sensitive adhesive (PS) forms a “mechanical bond” with the glass based on the pressure between film and glass.
- The film is stuck onto the glass. When the release liner is removed from a film with this type of adhesive, the film is “tacky”.
- Must be handled with care to prevent dust and dirt attaching to the film before it Is put on the window.
- Solar film is generally available with PS adhesive
- All safety film has pressure sensitive adhesives.
- When this type of film is removed, it is a matter of relieving the pressure by pulling the film away from the glass.
Clear Dry Adhesive
- Forms a chemical bond with the glass.
– Based on chemical attraction of like substance of the glass and adhesive.
- Clear Dry adhesives (CDA) forms a chemical bond with the glass, not a mechanical bond.
- Many installers prefer this type of adhesive when installing solar control film.
- When the release liner is removed from the film, the adhesive side is not “tacky”.
- Eases installation for less experienced installers or windows with large surface areas.
- Ultraviolet absorbers are necessary for life of film
- Three to four different absorbers are used to broaden the range of UV stopped.
- Special ultraviolet (UV) absorbers and inhibitors are used to keep the ultraviolet energy from the sun from breaking down the polyester film as well as the laminating and mounting adhesives.
- Three to four different UV absorbers are used in film to protect the various components as well as provide the broadest coverage against ultraviolet energy.
- In addition to protecting the film, it is this range of UV absorbers and inhibitors that provide protection against the fading of interior furnishings.
- An acrylic coating applied to the room side
- Protects polyester from scratching
- Scratch resistant coatings vary by manufacturer, but generally the SCR is an acrylic coating much like hard coat applied to automobile paint.
- Solar Gard exclusively uses hardcoat, scratch resistant hard coat. Hard coat is an acrylic-based coating that could be likened to combining the slip properties of non-stick cookware and the toughness of automotive paint.
- It is applied to the room side of the film to protect it from normal wear and tear and cleaning.
- H actually cross links to create a permanent, invisible shield which is securely bonded to the film.
- Glass Surface
- Adhesive Layer
- Metallized Polyester Film
- Hardcoat on the film makes for such a smooth surface that
- it is easier to clean than a window without film.
- Handprints are easier to wipe off.
- Hardcoat stands up to cleaners, chemicals and light scratches to help keep the film looking new.
- Instructor use a film without SCR (release liner is one) and have student scratch it as well as a coated piece of film to demonstrate the ease of scratching with and without SCR
- Which one scratched the easiest.?
- Can you see that an SCR makes a difference?
- Protects adhesive until installation using a polyester film coated with silicone -prevents sticking to adhesive .
- DPS – Detackified Pressure Sensitive Adhesive –
– Really a treatment of the liner rather than the adhesive
Note: Release liners distort the optical properties of film
- Release lines are critical to the storing and handling of film.
- Detackified pressure sensitive (DPS) is actually not an adhesive but rather a release liner
- DPS uses the same pressure sensitive adhesive applied as films using pressure sensitive adhesives.
- The difference is in the liner which is coated with a waxy gel. When the liner is removed the adhesive is not tacky. The gel on the liner transfers to the pressure sensitive adhesive that is on the film.
- The waxy gel dissolves when sprayed with the mounting solution. When squeegeed onto a window surface, this film forms the same pressure bond as a PS adhesive.
- The down side of DPS is that it takes a lot of water to dissolve the waxy gel.
- Instructor – Show how to remove a release liner from a sample and have everyone do it. Inspect both the film and the liner.
Bringing it all together…
To review the Tint Depot process:
- Rolls of optical grade polyester, are coated with laminating adhesive, the adhesive set, and nipped together with a roil of sputtered film to form solar control window film.
- Once nipped, the material is coated with hard coat then mounting adhesives, and the release liner applied.
- The product undergoes visual and laser inspection several times along the way before being rolled as finished goods
- A, B – Coated
- C and cured using either conventional ovens
- D or ultraviolet light
- E film is laminated
- F film is rewound