VW TL 52038 Adhesive Labels - Material Requirements

The standard "VW TL 52038 Adhesive labels - Material requirements," developed by Volkswagen, specifies the requirements for all self-adhesive labels used on vehicles. This standard also includes labels used by suppliers to identify components. This standard covers the material and testing requirements for self-adhesive labels used both inside and outside vehicles, as well as in the engine compartment.

The essential requirements are defined in this standard as follows:

• According to the VW 91101 standard, hazardous substances must be avoided.
• The standard atmosphere should be 23 degrees Celsius and 50 percent relative humidity in accordance with the VW 50554 standard.
• For adhesive labels in the vehicle interior, they must demonstrate emissions behaviour in accordance with VW standard 50180.
• Test results must be included in the initial sample documentation as evidence that the supplier meets legal requirements.

The structure, property and condition requirements are defined as follows:

• The carrier film must be flawless.
• The adhesive coating should be produced using acrylic ester-based adhesives.
• The surface of adhesive labels must be flawless, i.e., free of defects such as bubbles or residue.
• There should be no bubbles or spots even after subsequent laser tagging.
• In case of cuts in the carrier material, these cuts must have a uniform structure across the entire surface area or the entire label.
• The back of the label should be evenly coated with adhesive.
• Adhesive labels must be applied to the surface shown in the drawing and adhered to the surface in accordance with the peeling forces.
• The label must not be wrinkled, rolled, torn or peeled.
• The adhesive coating on the back side should be covered with a peelable protective film.
• The protective film must protect the adhesive from contamination and unwanted adhesion, and must be easily removable from the adhesive label without any pretreatment. Labels must adhere properly.
• The protective film is part of the sample examination.

Functional requirements are defined as follows:

• The requirements in the table titled “Functional requirements for adhesive labels” given in the standard apply.

Light fastness requirements are defined as follows:

• For in-vehicle applications, light fastness must be complied with according to the PV 1303 standard.
• For labels applied during vehicle production, the number of exposure times must be observed according to the application point of the label.
• For labels with an adhesive bond applied for part marking upon delivery, the light exposure time must be in accordance with the requirement for the surface on which the adhesive bond is located.
• For vehicle exterior applications, abrasion in dry and hot climates must be in accordance with the PV 3929 standard.
• For labels applied during vehicle production, the light exposure time should be appropriate to the requirements of the surface to which the adhesive will be bonded. There should be no visible color change or change in gloss level.
• In humid and hot climates, the coating must comply with the PV 3930 standard.
• The following applies to labels applied during vehicle production:
  • 1-year cycle: For parts under continuous, direct irradiation
  • 1/2 year cycle: For parts in shaded areas (e.g. in doorways)
• For labels with adhesive bonds applied for part marking upon delivery, the light exposure time must be consistent with the requirements for the surface on which the adhesive bond is applied. There should be no visible color change or change in gloss level.

The test procedures defined in this standard are:

• Shrinkage (dimensional stability)
• Ambient resistance
• Wear resistance
• Scratch resistance

When testing adhesive behavior, cut the adhesive labels if the labels are 100 mm long and 20 mm wide as received. For Type B, peel off the protective film from two-thirds of the sample length and cut off, leaving one-third of the adhesive label intact. For Types A and C, apply the label to the entire surface area. A protective film is placed at one corner, approximately 0,5 cm² below the label.

The samples are bonded to the center of the painted sheet test panels or to the center of the bonding surface specified in the drawing.

The recommended dimensions for the board test panel are 200 mm x 100 mm. Other dimensions are permitted. Board surfaces must be free of stains and dirt. Therefore, moisten a lint-free paper towel with an isopropanol/water mixture and wipe the surface with a single, light sweeping motion. A liquid film remaining on the cleaned surface after sweeping indicates that the paper towel is sufficiently damp. During the second sweep, the remaining liquid film should be absorbed by a dry portion of the paper towel. Finally, the cleaned surface is wiped dry.

The label is applied by pressing firmly and continuously, starting from the narrow side, using a felt pad (thickness 1,0 mm plus/minus 0,2 mm). Each paper test panel can be used only once.

Before aging or performing tests on test items and aging in standard atmospheres, condition the samples prepared as above in the standard atmosphere for at least 72 hours.

After removing the samples from the individual test articles and standard atmospheres, they are reconditioned for 24 hours in the standard atmosphere or 48 hours in the case of condensed water loading.

After resurfacing, adhesion is tested. Tear behavior is also tested immediately after removal at 90 degrees, 130 degrees, or -40 degrees.

For Type B, the test shall be performed as a peel test with a tensile testing machine using a roller support. Passage speed 50 mm/min, peel angle 90 degrees, peel distance approximately 15 mm. Five specimens shall be tested for each condition.

For Types A and C, the label is grasped by the unattached corner and slowly subjected to tensile load. The peel angle is allowed to vary during the test. Turns that cause increased loading on one label edge should be avoided. It should not be possible to remove the label without damaging it. Three samples should be tested for each condition.

During the evaluation phase, the resulting load-displacement diagram is used to evaluate the middle area (approximately 30 percent to 90 percent of the tested distance). For this area, the average peel strength value is determined as the benchmark value against the specification.

Our organization, which has been supporting businesses across all sectors for years through a wide range of testing, measurement, analysis, and evaluation activities, has a strong team of employees who closely follow global developments in science and technology and are constantly improving themselves. In this context, we also provide testing services in accordance with the "VW TL 52038 Adhesive Labels - Material Requirements" standard.