Adapta launches anti-adherent paint

Thousands of adverts plaster streetlights, traffic lights, road signs, and urban buildings in cities. The proliferation of this type of publicity incurs high costs for municipal coffers for cleaning and maintenance services. The situation has got to such an extreme point in the centre of large cities that councils have been compelled to penalise the practice, applying the municipal ordinance related to the protection of citizen coexistence and the prevention of antisocial behaviour.

Adapta, staying true to their innovative vocation in the search for new solutions, has developed a powder coating which enables the easy removal of a wide range of these adhesives. The product has been designed in super-durable quality (Adapta SDS) and its finish has a smooth texture or micro texture and can be manufactured in any colour. This product incorporates other functionality such as anti-graffiti features as well as its anti-adherent feature. Its high durability, alongside these possibilities of removing unwanted adhesives and easily cleaning the surface, allows the owners to keep several community elements clean in the face of vandalism, all at a low maintenance cost.

In order to evaluate the effectiveness of the coating, Adapta called on the services of the laboratories of the INESCOP Department of Adhesives (Footwear Technological Institute (INESCOP in its Spanish acronym)) and also on the laboratories of the Packaging, Transport and Logistics Research Center (ITENE in its Spanish acronym) by means of standard methods approved and developed internationally by the FINAT European Association (Féderation Internationale des fabricants et transformateurs d’Adhésifs et Thermocollants sur papiers et autres supports) to carry out materials tests for auto-adhesive materials.

The stickers used for the tests contain an adhesive based on rubber with a high adhesion to difficult and non-polar substrates. Among the main features that we can see on its technical information sheet are the following:

  • Service temperature: from -10 ºC to 70 ºC.
  • Tack (Stickiness): 16 N/25 mm. (FINAT FTM9 Loop tack measurement – Quick Stick) Task is used to measure initial adhesion. It is the resistive force of the adhesive lamina stuck to a surface in specific conditions. High stickiness indicates high adhesion facility, where unsticking it will be difficult and will cause the lamina to tear in many cases.
  • Final Adhesion (Force of detachment): 9 N/25 mm. (FINAT FTM2 Peel adhesion (90°) at 300 mm per minute) The force necessary to detach a pressure-sensitive adhesive from a standard test piece, to which it has been stuck under specific conditions, at an angle of 90º and for a set amount of time.

In the INESCOP Department of Adhesives (Report No. C-16026842) the product samples were tested according to the regulations:

UNE-EN 828:2013 “Adhesives, wettability. Determination by measurement of contact angle and critical surface tension of solid surface.”
The contact angle is the angle which a liquid forms with respect to the contact surface and is determined by the result of the adhesive and cohesive forces. This angle provides a measurement of the inverse of the wettability, since a drop’s tendency to spread out on a flat surface increases as the contact angle decreases.

The results determined by the goniometer viewing system are shown in the table below and the surface energy of the samples is calculated mathematically.

 Contact anglesSurface energy
Sample Water Diiodomethane(mJ/m2)
Normal texture763941.4
Anti-adherent texture976426.2

Image of the contact angle of the diiodomethane on the metal surface. On the left on the normally-textured transparent lacquer, and on the right on the anti-adherent-textured transparent lacquer.

The samples finished with an anti-adherent texture present contact angles which are noticeably greater than the samples finished with a normally-textured product, a fact which points to lower wettability, that is to say, the liquid is less able to spread itself out. On the other hand, the surface energy of the anti-adherent sample is considerably lower, something which is related to its low wettability and its low adhesion. It is therefore easier to detach adhesive stickers from the samples coated with the anti-adherent paint.

UNE-EN 1939:2004 Self adhesive tapes – Determination of peel adhesion properties to peeling at 90º.
To carry out this test, the stickers were placedon samples which were pressed mechanically between two rubber cushions (70º Shora A hardness) and under a pressure of 2.5 kg/cm2 for ten seconds.

Once the adhesive join had been made, the samples proceeded to be tested in order to determine their resistance to peeling at 90º, obtaining the following results:

Sample Peeling force*Appearances** (%)
(N/10 mm)
Normal texture3.560 M1 / 40 A2
Anti-adherent texture0.9100 A2

* 1 N/mm is approximately equal to 1 kg/cm.
** The percentage of each appearance is given as a guideline and in an approximate fashion.

Appearances: M1 Tearing of the adhesive sticker. A2 The adhesive detaches from the aluminium.

The value of the peeling force corresponding to the samples with the anti-adherent coating is substantially lower. Furthermore, the appearance observed following the separation of the materials in a total detachment of the adhesive from the anti-adherent coating and a majority tearing of the adhesive sticker on the normal coating, as can be seen in the following photograph.

Appearance of the separated surfaces following the peeling at 90º test in ambient laboratory conditions (Temperature: 23+2 ºC and Relative humidity: 50+5 per cent).

These results indicate that the anti-adherent coating applied to the metal surface is suitable for this type of substrate.

Measurement of the adhesion to peeling at an angle of 90º on a metal surface at low and high temperature.
In order to determine the adhesive properties by means of peeling at 90º at low and high temperature, the samples were prepared in climate-controlled chambers for 20 hours at 10ºC and 50ºC respectively. The table below shows the results obtained, having tested five test pieces of each material.

Sample Low Temp. = 10 ºCHigh Temp. = 50 ºC
Peeling force*Appearances**Peeling force*Appearances**
(N/10mm)(%)(N/10 mm)(%)
Normal texture1.1100 S13.540 M1 / 60 A2
Anti-adherent texture1.3100 A20.5100 A2

* 1 N/mm is approximately equal to 1 kg/cm.
** The percentage of each appearance is given as a guideline and in an approximate fashion.

Appearances: S1 Delamination of the adhesive sticker. M1 Tearing of the adhesive sticker. A2 The adhesive detaches from the aluminium.

The values for the peeling force corresponding to low temperature are similar. However, the appearance observed following the separation of the materials is the total delamination of the adhesive sticker on the sample painted with the product with a normal texture, and the complete detachment of the sticker with the anti-adherent texture paint.

Unsticking following preparation at 10 ºC.

On the other hand, in the case of the samples subjected to high temperatures, the value of the peeling force corresponding to the anti-adherent paint is significantly less and the appearance observed following the separation of the materials is that of total detachment of the adhesive compared with the tearing of the adhesive sticker for the samples painted with the product with a normal texture.

Unsticking following preparation at 50 ºC.

These results indicate that the treatment applied to the metal surface based on the anti-adherent coating is suitable for this type of substrate under the conditions tested.

Finally, in the ITENE laboratories (Report No. 02.0216), the adhesion strength against sticking at 180 º was determined according to internal procedures.
For the carrying out of this test the adhesive stickers were placed on the samples with a pressure applied of 0.12 kg/cm2 (5 kg over an area of 6.5 x 6.5 cm) for 10 seconds. Subsequently the tension test at 180 º was carried out on nine samples, each one with different paints.

The results obtained by testing the normally-textured paint are laid out in the table below:

 Determination of the penetration force
Normal textureForce at the tip (N)Average Force (10-60 mm) (N)
Average36.3518.64
Standard Deviation7.844.57

The results obtained by testing the anti-adherent paint are laid out in the table below:

 Determination of the penetration force
Anti-adherent textureForce at the tip (N)Average Force (10-60 mm) (N)
Average0.730.22
Standard Deviation0.150.13

As can be seen, the average value of the peeling force at 180º corresponding to the samples with the anti-adherent coating is substantially lower. Furthermore, the appearance observed following the separation of the materials in a total detachment of the adhesive from the anti-adherent coating and a majority tearing of the adhesive sticker on the normal coating.