Density of PET Film: Technical Data Sheet

Technical Scope

This technical data sheet applies to PET base film used in protective film, clear adhesive film, PET release liner, anti-scratch film, anti-static film, overlay film, and coated PET film for industrial surface protection or converting.

The focus is PET film density, specific gravity, film thickness, total thickness, GSM calculation, roll weight estimation, test method selection, surface compatibility, and sample peel testing. It does not replace a finished product specification or an application solution for glass, metal, plastic, painted panels, or electronics assembly.

For base substrate selection, compare this density data with industrial PET base film requirements.

Material / Product Structure

A PET protective film structure normally includes a PET base film, adhesive layer, optional surface treatment, and sometimes a release liner. The adhesive may be acrylic, silicone, PU, or another project-confirmed chemistry. Surface treatment may include corona treatment, hard coating, anti-static treatment, matte coating, tinting, or silicone release coating.

PET base film density and finished protective film weight should be separated. Density supports calculation; finished performance also depends on adhesive coating weight, total thickness, surface condition, dwell time, storage condition, and actual sample testing result.

When PET base film is combined with adhesive, check clear self adhesive PET film data rather than density alone.

For release-coated structures, PET silicone release liner data helps separate base film weight and release behavior.

Main Technical Data Sheet

Item	Typical Value / Reference Range	Test Method or Condition	Notes
PET base film density	1.38-1.40 g/cm3 typical range	ASTM D1505, ISO 1183-2, or agreed method	1.39 g/cm3 is often used for calculation.
Specific gravity	Approx. 1.38-1.40	ASTM D792 or equivalent	Reference value, not a finished film guarantee.
Film thickness	12-250 um typical range	Micrometer or thickness gauge	Directly affects GSM, yield, and roll weight.
Total thickness	Project-confirmed value	Film + adhesive + coating / liner if included	Needed for adhesive PET protective film.
Adhesive type	Acrylic, silicone, PU, or agreed chemistry	Material specification + sample test	Affects peel adhesion, edge lifting, and residue observation.
Peel adhesion	Project-confirmed value	180 degree peel, FINAT-style, or internal method	Should be tested on the actual target surface.
Tensile strength / elongation	Based on tested grade	ASTM D882 or equivalent	Supports handling, die-cutting, and removal checks.
Haze / light transmittance	Project-confirmed for clear film	ASTM D1003 or equivalent	Important for glass, display, acrylic sheet, and overlay use.
Storage condition	Cool, dry, original packaging recommended	Internal storage control	Temperature, humidity, sunlight, and storage time may affect results.

Test Methods and Conditions

Test Item	What It Checks	Suggested Method or Reference	Why It Matters	When To Request It
Density	Mass-to-volume relationship of PET base film	ASTM D1505, ISO 1183-2, or equivalent lab method	Supports GSM, yield, and roll weight calculation.	New grade or incoming material check
Thickness	Base film and finished construction thickness	Micrometer, gauge, or profile check	Explains weight variation and converting behavior.	Each new thickness, width, or coating structure
Peel adhesion	Adhesive force on the target surface	180 degree peel or equivalent method	Helps evaluate holding, removal force, and residue risk.	Coated, painted, polished, printed, or low energy surfaces
Haze / transmittance	Optical clarity of clear film	ASTM D1003 or equivalent	Supports visual inspection and transparent protection use.	Glass, display, acrylic sheet, and overlay projects
Tensile / elongation	Film strength and stretch behavior	ASTM D882 or equivalent	Checks tearing risk during handling or removal.	Thin, narrow, die-cut, or long-dwell samples
Residue observation	Adhesive trace, ghost mark, surface shadow	Sample peel test after dwell check	Density does not predict removal behavior.	Sensitive, coated, painted, or polished surfaces
Edge lifting	Edge stability after application	24h / 72h / 7 days observation	Shows risk of exposed surface during storage or transport.	Curved, rough, dusty, oily, or low energy surfaces

How To Read These Technical Values

PET film density is mainly a calculation and consistency value. It helps estimate PET film GSM, unit weight, film yield, and roll weight. It does not confirm peel adhesion, clean removal risk, haze, tensile strength, elongation, or surface compatibility. When replacing or comparing lower-density polypropylene film with PET, the BOPP and PET film comparison guide helps explain why equal thickness does not mean equal roll weight, stiffness, or converting behavior.

For calculation, a 50 um PET base film using 1.39 g/cm3 has an estimated base film weight of about 69.5 g/m2. Adhesive coating, release liner, paper core, tolerance, and winding condition should be added or excluded according to the agreed calculation scope.

Peel adhesion should be read with surface type, coating condition, temperature, humidity, dwell time, and operator method. Higher peel may improve edge holding but may increase removal force or adhesive trace risk. Lower peel may reduce removal force but may increase edge lifting or movement.

Tensile strength and elongation support handling and die-cutting checks. Haze and light transmittance matter where the protected surface must remain visible during inspection, storage, or assembly.

Application Compatibility Notes

Glass and clear plastic: check haze, light transmittance, bubble, surface shadow, and peel behavior after dwell time.
Metal and painted panels: check peel adhesion, residue observation, edge burrs, cutting fluid, sunlight exposure, and transport vibration.
Plastic sheet, acrylic, PVC, PC, and low energy surfaces: adhesive anchorage may vary, so sample testing is recommended.
Rough or textured surfaces: reduced contact area may cause local lifting even when adhesion grade appears suitable.
Curved or formed parts: film stiffness, total thickness, operator method, and cargo shape can affect edge stability.

For electronics handling, review PET ESD protective film specifications together with density data.

For coating, slitting, rewinding, and QC planning, protective film manufacturing capabilities explain how values are controlled.

Sample Testing Before Full Use

Sample testing should use the actual target surface, not only a standard laboratory panel. The sample should represent real coating condition, cleaning method, temperature, humidity, and storage time.

Apply the film with the same roller pressure, operator method, overlap condition, and handling process planned for production. Check peel behavior after 24h, 72h, and 7 days when longer dwell time is expected.

Observe edge lifting, adhesive trace, surface shadow, gloss change, bubble formation, film tearing, and residue after removal. For transport or converting work, also consider load weight, cargo shape, vibration, transport distance, equipment setting, and actual trial result.

Common Data Mismatch and Failure Risk

Data Point	If Too Low	If Too High	Risk in Application	Check Before Full Use
PET film density	Material mismatch may be hidden.	May indicate filled or different construction.	GSM and roll weight may not match actual supply.	Confirm sample type and method.
Film thickness	Lower handling and puncture margin.	Higher stiffness and roll weight.	Tearing, poor fit, or unexpected weight.	Measure cross-web and roll length.
Total thickness	Finished film may feel weak.	Film may be too stiff for curves.	Curling, poor contact, or converting difficulty.	Separate film, adhesive, and liner data.
Peel adhesion	Edge lifting or movement risk.	Higher removal force or adhesive trace risk.	Protection failure or removal difficulty.	Test on actual surface after dwell.
Tensile / elongation	Film may tear during removal.	Film may distort parts if over-stretched.	Tearing, shape distortion, or die-cut issue.	Check sample handling method.
Haze / transmittance	Surface may look unclear.	Not normally a high-risk issue if within target.	Inspection or appearance mismatch.	Use optical test and visual check.
Storage time	Fresh sample may not show aging behavior.	Long storage may affect adhesive.	Blocking, residue, edge lift, or roll flatness issue.	Compare retained and stored samples.

Storage and Handling Notes

Store PET protective film in clean, dry conditions away from direct sunlight, high temperature, high humidity, solvent vapor, dust, and excessive roll pressure. Original packaging helps reduce contamination, moisture exposure, and edge damage.

Rolls should be supported according to roll size and core strength. Heavy stacking, crushed edges, broken packaging, or uneven storage may affect roll flatness, winding tension, and application smoothness.

Storage time and transport condition can influence adhesive flow, peel force, residue observation, and edge lifting. When storage period is uncertain, compare retained samples with actual stored rolls before full use.

FAQ

What is the typical density of PET film?

The density of PET film is commonly referenced at 1.38-1.40 g/cm3 for PET base film. A nominal 1.39 g/cm3 is often used for GSM and roll weight calculation.

Is a typical value the same as a guaranteed value?

No. A typical value is a reference range. A project-confirmed value should be based on tested grade, agreed method, and actual sample testing result.

Why is sample testing required if density is known?

Density supports weight calculation, but it does not confirm peel adhesion, edge lifting, haze, tensile strength, elongation, or residue observation. A 24h / 72h / 7 days peel check is recommended before full use.

Does storage condition affect protective film performance?

Yes. Temperature, humidity, sunlight exposure, roll pressure, storage time, transport distance, and packaging damage may affect adhesive behavior and removal result.

Why can the same PET film behave differently on different surfaces?

Surface type, coating condition, roughness, cleaning method, temperature, humidity, and operator method all affect adhesion and removal behavior.