Q: Functionality and durability

Based on our current knowledge, the following functionality and durability can be expected for 3M Thermoscript films. Generally not below the following durations for vertical outdoor weathering, provided the foils have been professionally processed and applied according to 3M recommendations: Durability Outdoor use: 2-3 years Indoor use: almost unlimited Shelf life 2 years Recommended Storage Conditions 23°C / 50% relative humidity. Storage of film/label rolls in polybags is recommended.

Q: Processing

Careless peeling of the label from the release liner can lead to a so-called pre-destruction effect. To avoid this, the foil should be detached slowly, maintaining a 90° peel angle. The strength of the VOID effect is significantly influenced by the adhesive strength to the substrate. Therefore, thorough cleaning of contaminated substrates is particularly important. Full-surface and opaque printing of the labels should be avoided – this would make the VOID effect invisible. Printing Screen / Letterpress / Flexo / Offset printing processes A color qualification test before series production is recommended. Note: It is advisable to also test the base print for chemical resistance if necessary! Die-cutting Sharp knives and minimal web tension are recommended, to avoid possible adhesive squeeze-out. Substrate Pretreatment / Bonding See Processing Information KG-054

Q: Resistance

Resistance to climatic stress SFW 0.2 S DIN 50018 Stress 2 cycles: no change Film bonded to stainless steel, tested after 72 h storage in standard climate 23/50, DIN 50014. Resistance to Chemicals and Solvents The foils are resistant to most mineral oils and greases, fuels, aliphatic solvents, weak acids, salts, and alkalis, such as: Loading agent Loading time Result Heptane 4 h No deterioration Petroleum 4 h No deterioration Diesel 4 h No deterioration Engine Oil SAE 15W40 4 h No deterioration Windshield Cleaner 4 h No deterioration IPA 4 h No deterioration Industrial Cleaner (Lemon) 4 h No deterioration Pril 4 h No deterioration Acid (PH 4) 4 h No deterioration Alkali (PH 10) 4 h No deterioration Foil applied to stainless steel, tested after 72 hours of storage in standard climate 23/50, DIN 50014.

Q: Specifications

3M 7866, 7380: UL File No. MH 16411 3M 7937 UL File No. MH 11410

Question 1

Product Description

Accepted Answer

3M security foils have been specially developed for tamper-evident labeling. In an intact state, they are equipped with an invisible &#8220;VOID&#8221; lettering that remains on the substrate when removal is attempted. On the foil, this lettering appears as a blank space. Labels made from this material cannot be transferred without destruction.   
3M security films are equipped with a modified acrylate adhesive and are therefore also suitable for bonding to difficult and low-energy substrates such as polyethylene, polypropylene, or siliconized hammer-finish paints. All products in this series can be subsequently inscribed with variable information.

Question 2

Construction

Accepted Answer

Product
Color
Film
Thickness in mm
Adhesive
Thickness in mm
Release Liner
In mm (g/m²)
Release liner

7380
White matte
0,058
300
0.020
0.081
(80)
Densified paper,
siliconized on one side

7937
White matte
0,058
300
0.020
0.170
(153)
Poly-coated paper,
siliconized on one side

7866
White Glossy
0,050
300
0.020
0.081
(80)
Densified paper,
siliconized on one side

76799
Silver Glossy
0,050
300
0.020
0.077
(90)
Densified paper,
siliconized on one side

Due to the aluminum metallization, the silver glossy color is not recommended for bonding to circuit boards.

Question 3

Physical properties

Accepted Answer

Material
Polyester

Temperature Resistance
(bonded to aluminum)
7380, 7937, 7866
-40°C to +120°C
no visible change

76799
-40°C to 80°C
No changes
-40°C to 120°C
The VOID lettering becomes visible, the VOID effect remains functional

Dimensional Stability
(tested according to DIN 30646)
Index 02
(Shrinkage < 0.2%)

Dielectric Strength
(VDE 0303, T2)
80 kV/mm

Fire Behavior when Bonded
to Aluminum
Self-extinguishing after 15 seconds,
does not drip

Salt Spray
(according to DIN 50021 SS)
150 h
no deterioration

Fungal Resistance
fungus resistant, not fungus promoting

Substrate corrosion
does not cause corrosion on the bonded substrate

Adhesive
Self-adhesive, acrylate-based, Series 300, suitable for polyethylene and polypropylene

Adhesive Type
(according to DIN 30646)
PNS (permanently adhesive, low-temperature, special adhesive)

Minimum Application Temperature
+4°C

Question 4

Functionality and durability

Accepted Answer

Based on our current knowledge, the following functionality and durability can be expected for 3M Thermoscript films.
Generally not below the following durations for vertical outdoor weathering, provided the foils have been professionally processed and applied according to 3M recommendations:

Durability
Outdoor use: 2-3 years
Indoor use: almost unlimited

Shelf life
2 years

Recommended Storage Conditions
23°C / 50% relative humidity. Storage of film/label rolls in polybags is recommended.

Question 5

Processing

Accepted Answer

Careless peeling of the label from the release liner can lead to a so-called pre-destruction effect. To avoid this, the foil should be detached slowly, maintaining a 90° peel angle. 
The strength of the VOID effect is significantly influenced by the adhesive strength to the substrate. Therefore, thorough cleaning of contaminated substrates is particularly important. 
Full-surface and opaque printing of the labels should be avoided – this would make the VOID effect invisible.

Printing
Screen / Letterpress / Flexo / Offset printing processes
A color qualification test before series production is recommended.
Note: It is advisable to also test the base print for chemical resistance if necessary!

Die-cutting
Sharp knives and minimal web tension are recommended,
to avoid possible adhesive squeeze-out.

Substrate Pretreatment / Bonding
See Processing Information KG-054

Question 6

Resistance

Accepted Answer

Resistance to climatic stress
SFW 0.2 S DIN 50018
Stress 2 cycles: no change
Film bonded to stainless steel, tested after 72 h storage in standard climate 23/50, DIN 50014.
 
Resistance to Chemicals and Solvents
The foils are resistant to most mineral oils and greases, fuels, aliphatic solvents, weak acids, salts, and alkalis, such as:

Loading agent
Loading time
Result

Heptane
4 h
No deterioration

Petroleum
4 h
No deterioration

Diesel
4 h
No deterioration

Engine Oil SAE 15W40
4 h
No deterioration

Windshield Cleaner
4 h
No deterioration

IPA
4 h
No deterioration

Industrial Cleaner (Lemon)
4 h
No deterioration

Pril
4 h
No deterioration

Acid (PH 4)
4 h
No deterioration

Alkali (PH 10)
4 h
No deterioration

Foil applied to stainless steel, tested after 72 hours of storage in standard climate 23/50, DIN 50014.

Question 7

Specifications

Accepted Answer

3M 7866, 7380: UL File No. MH 16411
3M 7937 UL File No. MH 11410

Product	Color	Film Thickness in mm	Adhesive Thickness in mm	Release Liner In mm (g/m²)	Release liner
7380	White matte	0,058	300 0.020	0.081 (80)	Densified paper, siliconized on one side
7937	White matte	0,058	300 0.020	0.170 (153)	Poly-coated paper, siliconized on one side
7866	White Glossy	0,050	300 0.020	0.081 (80)	Densified paper, siliconized on one side
76799	Silver Glossy	0,050	300 0.020	0.077 (90)	Densified paper, siliconized on one side

Material	Polyester
Temperature Resistance (bonded to aluminum) 7380, 7937, 7866	-40°C to +120°C no visible change
76799	-40°C to 80°C No changes -40°C to 120°C The VOID lettering becomes visible, the VOID effect remains functional
Dimensional Stability (tested according to DIN 30646)	Index 02 (Shrinkage < 0.2%)
Dielectric Strength (VDE 0303, T2)	80 kV/mm
Fire Behavior when Bonded to Aluminum	Self-extinguishing after 15 seconds, does not drip
Salt Spray (according to DIN 50021 SS)	150 h no deterioration
Fungal Resistance	fungus resistant, not fungus promoting
Substrate corrosion	does not cause corrosion on the bonded substrate
Adhesive	Self-adhesive, acrylate-based, Series 300, suitable for polyethylene and polypropylene
Adhesive Type (according to DIN 30646)	PNS (permanently adhesive, low-temperature, special adhesive)
Minimum Application Temperature	+4°C

Durability	Outdoor use: 2-3 years Indoor use: almost unlimited
Shelf life	2 years
Recommended Storage Conditions	23°C / 50% relative humidity. Storage of film/label rolls in polybags is recommended.

Printing	Screen / Letterpress / Flexo / Offset printing processes A color qualification test before series production is recommended. Note: It is advisable to also test the base print for chemical resistance if necessary!
Die-cutting	Sharp knives and minimal web tension are recommended, to avoid possible adhesive squeeze-out.
Substrate Pretreatment / Bonding	See Processing Information KG-054

Loading agent	Loading time	Result
Heptane	4 h	No deterioration
Petroleum	4 h	No deterioration
Diesel	4 h	No deterioration
Engine Oil SAE 15W40	4 h	No deterioration
Windshield Cleaner	4 h	No deterioration
IPA	4 h	No deterioration
Industrial Cleaner (Lemon)	4 h	No deterioration
Pril	4 h	No deterioration
Acid (PH 4)	4 h	No deterioration
Alkali (PH 10)	4 h	No deterioration

Polyester Film VOID 7866