VW PV 3944 PVC Sunshades - Amine Color Change

The standard “VW PV 3944 PVC sunshades – Amine discoloration”, developed by the Volkswagen automobile company, describes a procedure for determining the color change of PVC films used for sunshades due to the action of amines.

For the purposes of this standard, amine discolouration refers to a permanent colour change resulting from the action of a polymerisation catalyst in PVC films for sunshades.

Typically, amines turn brown over time. However, amines can be made into a color-stable product by hydrogenation or by treatment with activated carbon or acid followed by distillation. However, the extra processing steps required in this way result in a loss of yield and increase the overall cost of a product processed in this way. Further research is ongoing to obtain color-stable amine products or to achieve color stability.

The electron density on aniline increases due to the effect of amine group (electron donor) and due to high electron density aniline is easily oxidized in air to give colored products. Therefore aniline becomes colored when left in air for a long time. Aniline appears as a yellowish to brown oily liquid.

Instruments used in amine color change tests include:

• Glass container with 1,3 l volume, tube lid and side olives (height 160 mm, inner diameter 100 mm) according to Witt
• Metal quick release to secure the cover
• Beaker 100 ml (height 70 mm)
• Beaker 150 ml (height 80 mm)
• Glass slide (76mm × 26mm)
• Grinding grease (temperature resistant)
• Forced ventilation heating cabinet (accuracy plus/minus 2K)
• A glass Pasteur pipette - Disposable, with rubber suction bulb
• Conical cork stopper (height 22 mm, top diameter 13 mm, bottom diameter 10 mm)
• Color measuring device
• Analytical balance (resolution 0,1 mg)
• Polymerization catalyst (67 percent dipropyl glycol and 33 percent triethylenediamine)
• PP/EPDM ribbon, white, maximum width 5 mm
• Laboratory dishwasher with deionized water

For each test material, 20 test specimens measuring 120 mm × 6 mm are required.

Samples are conditioned for at least 50554 hours in the VW 23 standard 50/2-24 standard climate.

When starting the test, the test samples are placed around the 100 ml beaker with their backs (i.e. the side that is not visible when inserted) facing the glass, so that approximately 5 cm of the sample length is inside the glass and the remaining sample length is on the outer glass wall. The samples are then secured with PP/EPDM tape at a height of 15 mm from the bottom of the beaker. The beaker with the test samples is prepared before the addition of the amine so that the glass beaker can be closed after the addition of the amine.

The following steps are then performed:

• Using a Pasteur pipette, weigh 30,0 mg of polymerization catalyst into a 150 ml beaker (corresponding to an amine concentration of 7 ppm when converted to beaker volume).
• The filled 150 ml beaker is placed in the centre of the Witt pot.
• The slide is placed in the 150 ml beaker.
• A beaker containing five test samples is placed on this slide.
• Place the glass jar lid with the glass stopper on the oiled grinder.
• The container and its lid are fixed with a quick release fastener.
• It is kept in a forced-ventilated heating cabinet at 90 degrees for 24 hours.
• The test sample is removed and measured colorimetrically.
• Four out of five samples are stored on white paper at 115 degrees for 24 hours.
• The test sample is removed and measured colorimetrically.
• Three of the four samples are kept on white paper at 115 degrees for 24 hours.
• The test sample is removed and measured colorimetrically according to the VW 50190 standard.

After the test times have elapsed, the test samples are measured colorimetrically against test samples of the same material (reference samples) stored in a normal climate. Colour measurement is carried out after the test samples have cooled down (i.e. after approximately 30 minutes). The measurement is carried out on the visible side (front side) of the samples, i.e. in the area positioned on the outside of the beaker in the test setup. The measuring point should be at least 5 mm from the PP/EPDM tape and 5 mm from the upper edge of the beaker. For better comparison, the test samples can be mounted on cardboard.

Among the numerous tests, measurements, analyses and evaluation studies that our organization has carried out for businesses in various sectors, it also provides testing services defined in the “VW PV 3944 PVC sunshades - Amine colour change” standard with its trained and expert staff and advanced technological equipment.