Haze Rises With Thickness: Reading the Toray Lumirror S15A PET Film

Toray Lumirror S15A PET Film is a one-side pretreated polyester film for adhesive tape at 25, 38, and 50 micron, and its haze climbs from about 2.6 to 4.8 percent as the film gets thicker

Between the thinnest and the thickest grade in the table, haze nearly doubles. Toray Lumirror S15A PET Film is described in its datasheet as a pretreated type for good adhesion, treated on one side, and its listed application is adhesive tape.

What the Haze Numbers Mean for Tape

Haze measures how much of the light passing through the film is scattered, so a lower number means a clearer film. S15A shows haze of about 2.6 percent at the thinnest grade, about 3.5 percent in the middle, and about 4.8 percent at the thickest (ASTM D1003). That rise is typical, because a thicker film scatters more light (a general explanation, not from this datasheet).

For adhesive tape, it shapes the choice. If a clear tape is going to be seen on a surface, the thinner grade is the clearer one. If clarity does not matter, the thicker grades give more body and strength, at the cost of a milkier look.

The Numbers the Datasheet Gives

  • Thickness: 23, 38, and 50 um (the table headings read 25, 38, and 50)
  • Tensile strength: about 227 to 265 MPa, strongest in the thinnest grade (ASTM D882)
  • Elongation at break: about 120 to 155 percent, with the thinnest grade a little lower in MD (ASTM D882)
  • Heat shrinkage at 150°C for 30 minutes: about 1.1 percent in MD and about 0.3 to 0.4 percent in TD (ASTM D1204)
  • Haze: about 2.6, 3.5, and 4.8 percent, rising with thickness (ASTM D1003)
  • Breakdown voltage: listed, with one visible figure of about 2.2 that cannot be matched to a thickness (ASTM D149)

Strength is highest in the thin grade, which makes sense for a tape backing that has to withstand pulling and slitting. Low TD shrinkage helps the film stay flat when an adhesive is coated and dried. Note that MPa is force per unit area, so a thicker film can still carry more total load.

What “One Side Pretreated” Means

The datasheet says S15A is pretreated for good adhesion on one side, and the property listed is simply one-side pretreatment for good adhesion. In general, this means one face is prepared to anchor the adhesive layer, and the other face stays as plain polyester, which suits a tape where the adhesive goes on one side and the back is left bare or printed (a general explanation, not from this datasheet). The datasheet does not say what kind of treatment is used or how strong it is.

How It Differs from Neighboring Grades

  • Toray Lumirror S105 PET Film is also a one-side treated film in similar thicknesses (23 to 75 um) and similar strength, but it is corona treated and listed for labels, adhesive tape, and FPC bonding.
  • Toray Lumirror S85S PET Film is pretreated on one side at 50 and 75 um, listed for graphics, without published haze values.
  • Toray Lumirror T70A PET Film is a high transparent film at 16 and 25 um, a better match if the tape must be very clear.

What the Datasheet Does Not Say

  • The values are typical data under specific test conditions and are not limiting specifications, as the datasheet itself notes.
  • No wetting tension, surface tension, friction, light transmittance, or thickness tolerance is listed, and no adhesion test data are given.
  • Some figures could not be matched to a specific thickness. Please check the official datasheet for exact values at your thickness.

Quick Answers

What is Lumirror S15A?
A one-side pretreated polyester film for good adhesion, in 23, 38, and 50 um.

What application does the datasheet list?
Adhesive tape.

Which thickness is clearest?
The thinnest grade, with haze of about 2.6 percent.

Can I buy Toray Lumirror S15A PET Film from Jinlu Film?
Yes. Jinlu Film supplies Toray Lumirror S15A PET Film. If you prefer a comparable-specification alternative, including domestic options, we can offer those as well, together with datasheets and samples so you can test them on your own line.

More PET Film Guides

Sourcing Tape Backing Film

Jinlu Film supplies Toray Lumirror S15A PET Film, along with comparable one-side pretreated polyester film grades, including domestic alternatives, for adhesive tape applications. Tell us your adhesive, thickness, and clarity needs, and contact us for technical data, samples, or a factory quote.

Source: Toray’s publicly available Lumirror S15A technical data sheet (typical values). Please refer to the latest official version. Lumirror, Toray, and related names are trademarks of their respective owners. This article is an independent explanation for reference only.

toray lumirror s15a pet film

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