Mylar is an extremely recognized polyester film. Its excellent mechanical and chemical properties have helped fuel its popularity; in fact, Mylar is commonly used in everyday language to refer specifically to any plastic film.
The applications of Mylar are variable and include helium-filled balloons, food packaging, and electrical and thermal insulators.
Mylar was invented in the mid-1950s by Imperial Chemical Industries (ICI), Hoechstand, and DuPont, and is a registered trademark of DuPont Teijin Films.
In this article, we will define film Mylar. We will discuss how it is made, what its properties are, and what Mylar is used for.
What Is Mylar?
Mylar is a plastic film that is prized for its useful properties and attributes chemical stability and dimensional stability, electrical insulation, impermeability, tensile strength, reflectivity, and transparency.
The term Mylar is often used generically to describe any of the plastic films that are available. Mylar is not the only PET film made by DuPont Teijin Films. Other trade names include: Melinex and Hostaphan, which also are popular PET films.
What Is Mylar Made Of?
Mylar, a product produced by polyethylene terephthalate (PET), is a product that is produced from the scientific name BoPET (biaxially-oriented polyethylene terephthalate). The process of making Mylar involves:
- Melting a PET polymer and feeding it to an extruder and then through a chilled drum roller to create a film.
- Stretching the film biaxially, in the machine or feed direction and then in the transverse (width) direction. This is done by accumulating film over a series of rollers and then feeding it into a stenter frame where it was stretched in the transverse direction. This process of stretching orients PET molecules to increase the mechanical properties of the film.
- Heating the film to 200°C (392°F) to stabilize the structure of the film and to prevent the film from shrinking below the original heat set temperature.
At the conclusion of the fabrication process, the Mylar film is so smooth it wants to stick to itself. Mylar material is usually coated with silicon dioxide (SiO2) as a way to de-stickify.
Mylar can also be coated with evaporated gold, aluminum or some other metal (using a physical vapor deposition process) as a means of reducing transparency, increasing reflectivity and making it less permeable to gases.
What Are the Properties of Mylar?
Mylar’s versatility and ability to retain its various properties in a wide range of temperatures (-94°F to 302°F or -70°C to 150°C) make it suitable for a wide variety of applications in different industries.
Mylar can be used in very low and high temperatures (-418-392°F or -250-200°C) unless the mechanical requirements are too severe. Very extreme temperatures can lead to degradation of Mylar’s tensile strength and ductility. The properties of Mylar are listed below:
- Tensile strength of 29 ksi is pretty good
- Has excellent dimensional stability even through vast temperature ranges
- Are chemically inert, exhibited resistance to oils, solvents, moisture, and grease
- Has low permeablility, able to act as barrier against most liquid and gasses
- Has excellent thermal stability with a low thermal expansion coefficient of 1.7 × 10–5 in/in/°C (9.5 × 10 –6 in/in/°F). So it’s a great thermal insulator.
- Has high electrical resistivity of conductive material such as 1018 ohm⋅cm, excellent an electrical insulator.
- Highly reflective and when coated with metallic particles enhances thermal stability and has aesthetic value
- Uncoated, Mylar is transparent and transmits 80 – 90% of radiation in the visible and infrared spectrums so in certain application of tags, and equipment labeling ,this is desired.
What Are the Uses of Mylar?
In general, mylar is a wonderful material with strength and dimensional stability over a wider range of temperatures than a lot of other types of materials. Its mechanical properties alone make the mylar a versatile material.
Additionally, mylar’s low permeability makes mylar fantastic packaging for food and its electrical properties make it a superior electrical insulator.
Some common uses of Mylar are in:
- Flexible food packaging comprised of: yogurt lids, potato chip bags, foil coffee pouches, and candy wrappers
- Packaging of products like clothing, books, or other consumer products
- Labels, stickers, and tags for products
- Thermal insulators for air ducts, tents, survival blankets, and other heat/cold sensitive products
- Electrical insulators for electrical applications
- Decorative balloons, party decorations, kites, and other items
Can Mylar Be Used in Laser Cutting?
Mylar can indeed be laser cut. The typical available Mylar thickness is not beyond any standard laser cutting service.
A major benefit of Mylar is its low thickness and also its relatively low vaporization temperatures (662°F or 350°C) for plastic when compared to other materials like Delrin. This means it easy to cut with a laser!
What Are the Uses of Mylar in Laser Cutting?
Mylar is frequently processed with laser cutting because Mylar can be easily cut and can be laser cut with entry-level cutting systems. In addition to its durability and flexibility, Mylar is an ideal choice for many plastic film applications.
Laser cutting achieves the best results because Mylar can vaporize quickly with heat. Mostly laser-cut Mylar is used to manufacture stencils for crafting applications, but laser-cut Mylar can be used for many applications, including creating intricate patterns, shapes, and designs, or manufacturing food packaging products.
How Is Mylar Used in Stencils?
Mylar is frequently used to create stencils for crafts and hobbies. Laser cutting is frequently used to cut stencils because of the excellent quality of cuts the laser makes.
Other materials, including cardboard and cardstock, are also commonly used to laser cut stencils; card stock and cardboard can be cut into a stencil but will not make a clean piece of art. In addition these materials are not durable and can easily lose their shape.
How To Use Mylar for Making Stencils
When laser cutting Mylar stencils, use low power and high cutting speed so that the cut edges of the sheet do not melt and then vaporize. The following steps detail how to use Mylar for stencil making purposes, by way of laser cutting:
- Put the backer board, either cardboard or cardstock, underneath the Mylar sheet. This will preserve the laser work table, or the area directly below the laser from being damaged by the laser.
- Use a glue stick, spray adhesive or tape to adhere the sheet to the backer board. Now, use tape or a clamp to adhere the backer board to the work table. This will prevent the sheet from sliding during the laser cut. It will also make it easy to remove the final stencil because the unwanted parts will stick to the backer board.
- Set up the laser system to cut Mylar material. You want the cutting speeds to be quickly enough to prevent melting of the material without excessive melting. The power needed to cut the Mylar sheet depends on the thickness of the sheet.
Table 1 below shows the recommended power settings and speeds for cutting various thicknesses of Mylar:
Table 1: Mylar Recommended Laser Power Settings
| Sheet Thickness | Laser Power | Cutting Speed |
|---|---|---|
| 0.1 | 7 W | 150 mm/s |
| 0.20 mm | 8 W | 150 mm/s |
| 0.25 mm | 9 W | 150 mm/s |
| 0.25 mm | 9 W | 150 mm/s |
Frequently Asked Questions About Mylar
What Is the Ideal Mylar Thickness for Laser Cutting Stencils?
The recommended thickness for Mylar when laser cutting stencils is 0.1 to 0.2 mm. All Mylar can be laser cut no problem using any laser system, however thick Mylar would not be a good solution for making stencils. Thicker sheets would pose a challenge when using them as stencils for drawing and art.
Is Mylar Expensive?
No, Mylar is not costly. Mylar can be purchased in packs of individual sheets, in whole rolls, or as bags. For as little as $50 you can buy a roll of Mylar as large as 4 ft x 100 ft. This size roll has enough material for several projects.
Is Mylar a Reflective Material?
Yes, Mylar is a great reflective material but it can also be made as a matte material, or can be made clear. Mylar is commonly used for thermal insulation due to its reflective qualities. It can be used in things like food packaging and survival blankets, where keeping heat in is more important than anything else.
Is Mylar Chemically Reactive?
Mylar exhibits a degree of chemical inertness when in contact with other materials such as oils and solvents; it does not react with these materials. Thus, the chemical inertness facilitates the cleaning of Mylar. Mylar is not only chemically inert, but it is also impermeable which provides a tremendous barrier against gasses and odors.