Waterproof Transparent Pet Release Film
Waterproof Transparent PET Release Film — the Liner That Decides How Clear Your Protective Film Looks A transparent protective film — a screen protector, a device protection film, an optical film, a window film — is only as clear as the liner it was cast against. The liner is the last thing touching the adhesive before it is wound, and its surface, its cleanliness and its release behaviour are replicated onto your product. Get the liner right and the film is clear, flat and sticks where it should. Get it wrong and you get haze, visible defects, and protective films that lift at the edge. This film is the liner for that job: transparent, non-porous PET with a silicone release coating, in the thicknesses and widths protective film lines run. Material: PET film with silicone release coating, single or double sided Thickness: 25 / 36 / 38 / 50 / 75 / 100 / 125 µm Width: slit from 20 mm up to 2000 mm Roll length: 100 – 3000 m · core 3" or 6" Optical: light transmittance ≥ 88 % · haze 1.5 – 3.5 % Water absorption: < 0.4 % — the film does not swell in humid conditions
- Fast Delievery
- Quality Assurance
- 24/7 Customer Service
Product Introduction
Products Description
What This Film Is
It is a release liner. A PET film with a silicone release coating, supplied to a protective film manufacturer to carry the adhesive through coating, lamination and slitting, and then to release when the end user applies the film to a device.
It is not a vacuum-bagging release film. Some release film pages describe "controlling the resin content of the laminate" in composite vacuum bagging - a different industry and a different product. If a supplier page selling you a transparent protective-film liner talks about resin and vacuum bags, the page was not written for your application.
It is not a dry-film. It carries no adhesive of its own.
And it is not PET cloth. PET is a film. If a specification says "PET cloth backing," it is describing a fabric-backed tape, not a release liner
The Liner's Surface Becomes Your Adhesive's Surface
This is the single most important thing to understand about a protective film liner, and it is why a cheap liner is a false economy.
Protective film adhesive is soft and pressure-sensitive. When it is coated or laminated against the liner, the adhesive takes on the surface profile of whatever it is pressed against - including the liner. That texture is then locked in when the film is wound.
| If the liner is… | Your protective film ends up… |
|---|---|
| Smooth and clean | Clear, with the optical properties your PET was chosen for |
| Rough or contaminated with particulate | Hazy - the adhesive's surface is a copy of the liner's surface |
| Prone to silicone transfer | Variable adhesion, residue, and possible optical defects from silicone at the bond line |
| Dimensionally unstable | Wound with tension variation, and lifting at the edges after application |
Optical Requirements: Transmittance, Haze and Rainbow
| Property | Typical value for our film | Why it matters |
|---|---|---|
| Light transmittance | ≥ 88 % | Directly sets how clear the finished protective film can be |
| Haze | 1.5 – 3.5 % | Measured haze; drift here shows up as a milky look on the device |
| Interference / rainbow pattern | No rainbow pattern - specified and inspected | Fails visual acceptance on display and optical parts |
| Coating uniformity | Uniform, no streaks or voids | Streaks in the silicone become streaks in the adhesive surface |
| Wrinkles, scratches, bubbles | Not acceptable | Mechanical defects that transfer to the adhesive |
What "Waterproof" Actually Buys You Over a Paper Liner
PET is non-porous and does not absorb water. A paper liner does. That difference is the whole reason a PET liner is specified where humidity, wet processes or dimensional accuracy matter.
| PET release film | Paper release liner (glassine, kraft, CCK) | |
|---|---|---|
| Water absorption | < 0.4 % - effectively non-absorbing | 5 – 10 % |
| Swelling in humid air | Negligible | Measurable; the sheet grows and shrinks with humidity |
| Dimensional stability | Holds dimensions across the roll, in any season | Varies with plant and warehouse humidity |
| Moisture given up to the adhesive | None | The liner can release moisture into the adhesive |
| Behaviour in wet processes | Unaffected | Degrades; fibre swells and loses strength |
| Fibre shedding | None - it is a film | Fibres at slit edges |
Where this matters in practice:
Humid plants and long storage. A paper liner stored in a humid warehouse absorbs moisture and changes dimension. A PET liner does not, so registration and tension stay the same from the first metre to the last.
Wet-install protective films. Screen protectors are frequently applied wet. The liner must not be affected by the water or the surfactant solution.
Optical substrates. Moisture released from a paper liner into the adhesive can affect clarity and adhesion. PET gives up nothing.
Very thin, wide webs. At 25 µm and 2000 mm wide, dimensional stability is not a nice-to-have; a swelling paper liner cannot hold registration across that web.
A caution on the word "waterproof": PET is a moisture barrier because it is non-porous, but a liner is not a waterproofing product - it is a carrier that is removed. If you need a permanent moisture barrier as part of a construction, that is a different specification. We will help you define it.
Silicone Transfer: The Failure That Reaches the Customer
A liner can release perfectly and still ruin your product, because a liner has two jobs and most pages only describe one of them:
Release the adhesive when it should
Not contaminate the adhesive it is protecting
If silicone migrates from the liner into the adhesive, the adhesive loses tack. On a protective film that shows up as edge lift, a film that falls off, or residue left on the device. The problem appears weeks after shipment, at the customer, and it is almost always blamed on the adhesive - not on the liner that caused it.
Require two numbers, not one:
| Specification | Test | What it tells you |
|---|---|---|
| Release force | FINAT FTM 3 (low speed), FTM 10 (high speed) | Whether the film releases at the right force on your line |
| Subsequent adhesion | FINAT FTM 4 | Whether the liner has contaminated the adhesive - expressed as a percentage of a control |
Under-cured silicone is the usual root cause of transfer, which is why cure completeness should be checked on every batch, not sampled. Ask any liner supplier for both release force and subsequent adhesion. A supplier who can only give you the first number is not testing the failure mode that matters most here.
Optical data (typical)
| Property | Value |
|---|---|
| Light transmittance | ≥ 88 % |
| Haze | 1.5 – 3.5 % |
| Interference pattern | No rainbow pattern |
| Tensile strength MD / TD | ≥ 120 MPa / ≥ 140 MPa |
| Elongation at break MD / TD | ≥ 80 % |
| Thermal shrinkage MD / TD | ≤ 1.5 % / ≤ 0 – 0.2 % |
| Wetting tension | ≥ 42 mN/m |
Cleanroom and Particulate
On an optical product, a particle is not a cosmetic issue - it is a visible defect and a rework.
A speck of dust trapped between the adhesive and the device screen becomes a permanent bubble or bump under the protector. Unlike a scratch, it cannot be polished out. It is removed by peeling the film off and starting again, which on a display line means scrapping the part.
| Control | Why it matters |
|---|---|
| Cleanroom coating and slitting | The liner is the last surface against the adhesive before it is wound |
| No fibre shedding | A film sheds no fibre; a paper liner does, at every slit edge |
| Burr-free slit edges | Burrs generate particulate and can mark the adhesive |
| Anti-static option | Static attracts airborne dust onto the liner face |
| Clean packaging |
Protection during transport is part of the specification |
Applications
| Application | What the liner must deliver |
|---|---|
| Screen protectors - phone, tablet, watch | Optical clarity, no rainbow, no particulate, reliable wet and dry application |
| Device protection film | Clean release, no silicone transfer, dimensionally stable for thin film |
| Display and optical film | High transmittance, low haze, streak-free coating |
| Window film and architectural film | Wide-web dimensional stability; resistance to moisture during installation |
| Automotive paint protection film (PPF) | Clean release from a soft, thick adhesive; no residue; wide slit widths |
| Camera lens and sensor protection | Minimal particulate, no interference pattern |
| Laptop and housing protection film | Cost-efficient liner at volume, consistent release |
Hot Tags: waterproof transparent pet release film, China, suppliers, wholesale, buy, price, Silicone Coated PET Release Film, Release Paper
