Technical Field

The invention relates to a step in a process for treating a surface prior to application of further layer(s) of for instance coatings, adhesives or other materials, involving covalent grafting of a molecule such as a polymer by heating the object and using the heat to initiate a polymerization reaction.

Background

WO 1998/034446 discloses that suitable monomers together with a photoinitiator can be selectively inoculated on the surface of a non-conducting substrate in a distinct pattern by using irradiation with UV-light. Metal ions are thereafter absorbed by these monomers and are reduced. To this pattern further conducting materials, e.g., metals, can thereafter be added in a conventional way. The method according to the invention comprises a fully additive method to produce a circuit board with high resolution and the production of functional components directly on a non-conducting substrate.

WO 2007/116056 discloses a method for applying a first metal on paper, which method comprises the steps a) producing polymers on the surface of said paper, said polymers comprising carboxylic groups and adsorbed ions of at least one second metal, said ions being adsorbed at a pH above 7, b) reducing said ions to the second metal and c) depositing said first metal on the reduced ions of said second metal. The invention further comprises objects manufactured according to the method. WO 2007/116057 discloses a method for applying a first metal on a substrate, which method comprises the steps a) producing polymers on the surface of said substrate, said polymers comprising carboxylic groups and adsorbed ions of at least one second metal, said ions being adsorbed at a pH above 7, b) reducing said ions to the second metal and c) depositing said first metal on the reduced ions of said second metal. The invention further comprises objects manufactured according to the method.

WO 2012/066018 discloses a method for applying a metal on a substrate comprises: a) applying a coating by treatment in a plasma, comprising a compound selected from alkanes up to 10 carbon atoms, and unsaturated monomers, and bl ) producing polymers on the surface of said substrate, said polymers comprising carboxylic groups and adsorbed ions of a second metal, reducing said ions to the second metal, or alternatively b2) producing polymers on the surface, bringing the surface of said substrate in contact with a dispersion of colloidal metal particles of at least one second metal, and c) depositing said first metal on said second metal.

WO 2013/167598 discloses a process for application of metal on a substrate surface comprises applying a mixture of a solvent, a polymerizable monomer, and a photoinitiator on a substrate surface, wherein the photoinitiator does not form two phases together with the monomer and the solvent, i.e. it forms an amorphous mixture without any crystals. The monomer is able to polymerize to a polymer comprising at least one carboxylic group. Thereafter the solvent is evaporated. Polymerization is induced by irradiating the applied dried mixture. Ions are applied and reduced to metal and thereafter further metal can be deposited. The method can be used in industrial processes, both 2D and 3D surfaces can be coated with metal. Materials sensitive to standard grafting chemicals and/or polymers containing halogen atoms can be coated.

WO 2014/086844 discloses a method for application of a metal on a cavity filter comprising contacting at least a part of said cavity filter base with a mixture, and inducing a polymerization reaction by exposure to at least one selected from heat and actinic radiation adapted to said at least one initiator to form polymers on at least the inner surface of said cavity filter base, said polymers comprising at least one charged group, and said polymers forming covalent bonds after reaction with at least one selected from an abstractable hydrogen atom and an unsaturation on said cavity filter base, and subsequently applying further metal.

WO 2015/165874 discloses a method of metallizing substrate with abstractable hydrogen atoms and/or unsaturations on the surface, comprising the steps: a) contacting the substrate with a polymerizable unit, at least one initiator which can be activated by both heat and actinic radiation, and optionally at least one solvent, b) inducing a polymerization reaction c) depositing a second metal on an already applied first metal to obtain a metal coating. A first metal is added as ions and/or small metal particles during the process. Ions are reduced to the first metal. WO 2015/165875 discloses a method for application of a metal on a substrate, comprising the steps: a) contacting at least a part of the surface of the substrate with at least one selected from: i) at least one initiator, and a polymerizable unit with the ability to undergo a chemical reaction to form a polymer, said polymer comprising at least one charged group, and ii) a polymer comprising at least one charged group. The contacting is achieved by contacting a pad with a plate comprising the at least one substance and subsequently contacting the pad with the surface of the substrate, thereby transferring the at least one substance to the surface of the substrate. Subsequently a metal layer is produced on the surface.

US 2006/0211236 discloses a process for coating a surface of a substrate with a seed film of a metallic material, said surface being an electrically conductive or semiconduct ive surface and having recesses and/or project ions.

US 4,110,521 discloses a method where preheating is used for heating the temperature of a bulk solution before final heating.

WO 2014/039965 discloses a method for molding a composite structure including preheating to a temperature that renders the composite material more drapable, but is less than a temperature that causes the resin in the material to initiate polymerization. The ply of composite material is then transferred to a press station where it is heated to a temperature that causes the resin to initiate polymerization. US 4,954,371 discloses a solution comprising monomers, which are brought into contact with a heated surface. Various methods of polymerizing are mentioned. E-beam is preferred, but thermal is also mentioned. Grafting onto the surface does not take place, instead a film is formed. The entire thickness of applied monomers are polymerized.

US 2017/0044337 discloses thermoset /thermoplastic composites that include a thermoset component directly or indirectly bonded to a thermoplastic component via a crosslinked binding layer between the two. The crosslinked binding layer is bonded to the thermoplastic component via epoxy linkages and is either directly or indirectly bonded to the thermoset component via epoxy linkages. The composite can be a laminate and can provide a route for addition of a thermoplastic implant to a thermoset structure.

W020 04071644 discloses a surface modification process. The process includes initial epoxy modification of a substrate surface by attachment of an epoxy-containing polymer to the surface. Following attachment of the polymer, still-existing epoxy groups on the polymer may then cross-link the polymer to form a unified anchoring layer on the surface. Other epoxy groups in the anchoring layer, not utilized in forming the layer may be used to graft surface modifying materials to the surface. For instance, macromolecules, biomolecules, polymers, and polymerization initiators may be grafted to the surface via the anchoring layer. GB2108987 discloses an in-mold coating composition and method of in-mold coating. There is disclosed that an FRP molding can be in-mold coated using a one-component free radical peroxide initiated composition of (a) a polymerizable oligomer.

Although the technology according to the state of the art is working satisfactory there is still room for improvement, especially for certain cases. In the prior art it is not disclosed how to promote surface grafting as compared to bulk polymerization. One problem in the prior art is how to improve the adhesion.

For UV-initiated reactions there is a problem with difficult geometries, such as cavities and other similar shapes, where it is difficult or impossible to obtain good irradiation with UV-light.

Further for heat initiated reactions and/or combinations of initiation with both heat and actinic irradiation, there is the problem that the heat initiation is not sufficiently efficient. For similar heat initiated reactions in the prior art it has been necessary to combine the heat initiation with irradiation with actinic irradiation such as UV in order to obtain sufficient initiation in many cases.

When the surface treatment is carried out in a normal atmosphere there is the problem that oxygen reacts with the radicals formed by the initiator and thereby reduces the efficiency of the initiator. In large scale it is difficult and expensive to have an atmosphere with low concentration of oxygen. Summary

It is an object of the present invention to alleviate at least some of the problems in the prior art and to provide a method for treating a surface to increase adhesion before coating or gluing it.

In a first aspect there is provided a method for treating a surface of an object comprising the sequential steps of a) heating the object, and b) contacting at least a part of the surface of the object with a solution comprising a thermal initiator and a polymerizable molecule, wherein the surface of the object comprises reactive groups selected from abstractable hydrogen atoms and C=C double bonds, wherein the polymerizable molecule is able to undergo a reaction with the reactive groups on the surface of the object to form a covalent bond, wherein the polymerizable molecule is able to undergo a polymerization reaction to form a polymer, wherein the object is heated at least to a temperature where the thermal initiator is active, wherein polymerizable molecules are covalently bound to the surface of the object in step b), by a reaction initiated by heat from step a) and the thermal initiator, and a final step c) of contacting the polymerizable molecules covalently bound to the surface of the object with at least one organic molecule.

In a second aspect there is provided an object coated according to the method as described above.

One advantage is that a high radical concentration is obtained since the solution in contact with the object is heated quickly. The heat from the object heated in step a) triggers the thermal initiator so that it can start a reaction between the polymerizable molecules and the surface groups of the object. The high radical concentration makes the process less sensitive to inhibition by oxygen, which otherwise may consume the formed radicals so that the initiation becomes less efficient. Oxygen dissolved in the solution will be consumed by the high concentration of radicals and there is still a remaining sufficient amount of radicals to perform an efficient initiation of the desired reaction. The reaction is quick so that diffusion of additional oxygen from the surrounding is very limited.

The radical concentration is highest closest to the surface in the applied solution and this gives a higher degree of formation of covalent bonds to the surface, i.e. a higher density of grafted molecules/polymers on the surface. The radical concentration is highest closest to the surface because the heating is carried out from the object into the applied solution comprising the thermal initiator. This favours covalent bonding to the surface compared to bulk polymerization .

Since the radical concentration is highest in the applied solution closest to the surface of the object, the grafting at the surface is favoured compared to polymerization in the bulk of the applied solution of non-covalently bound polymers.

Further the coating is independent on irradiation with light and thereby complicated geometries can be coated as long as the solution can be applied to the surface to be coated. In order to achieve those advantages the object can only be heated before application of the thermal initiator, not after or during application of the thermal initiator. In the prior art this particular feature is not disclosed.

Detailed description

The following detailed description discloses by way of examples details and embodiments by which the invention may be practised.

It is to be understood that the terminology employed herein is used for the purpose of describing particular embodiments only and is not intended to be limiting since the scope of the present invention is limited only by the appended claims and equivalents thereof.

If nothing else is defined, any terms and scientific terminology used herein are intended to have the meanings commonly understood by those of skill in the art to which this invention pertains.

In a first aspect there is provided a method for treating a surface of an object comprising the sequential steps of a) heating the object, and b) contacting at least a part of the surface of the object with a solution comprising a thermal initiator and a polymerizable molecule, wherein the surface of the object comprises reactive groups selected from abstractable hydrogen atoms and C=C double bonds, wherein the polymerizable molecule is able to undergo a reaction with the reactive groups on the surface of the object to form a covalent bond, wherein the polymerizable molecule is able to undergo a polymerization reaction to form a polymer, wherein the object is heated at least to a temperature where the thermal initiator is active, wherein polymerizable molecules are covalently bound to the surface of the object in step b) by a reaction initiated by heat from step a) and the thermal initiator, and a step c) contacting the polymerizable molecules covalently bound to the surface of the object with at least one organic molecule.

The at least one organic molecule is typically a solution comprising organic molecules of a certain type of a mixture of organic molecules of different types. Such organic molecules can then bind to the already covalently bound polymerizable molecules covalently bound to the surface of the object.

The steps are intended to be carried out in sequential order a, b, and c.

The object is heated to a temperature which equals or is above the temperature at which the thermal initiator is active. The thermal initiator decomposes when heated and forms a radical which can initiate a reaction. The thermal initiator is usable in a certain temperature window. The object is heated so that the heat from the object initiates the reaction, when brought into contact with the solution comprising the initiator and the polymerizable molecule. The polymerizable molecule reacts with groups on the surface of the object after initiation so that the polymerizable molecule becomes covalently bound to the surface of the object.

The thermal initiator and the material in the object should be adapted to each other. The object must be able to withstand the temperature at which the thermal initiator in the solution is active, at least a part of the usable temperature range of the thermal initiator. Thus the object and the thermal initiator should be selected so that the thermal initiator can be active at a temperature which does not have any negative impact on the object. For instance, thermoplastic polymers often have a relatively low softening temperature and this has to be considered when selecting the thermal initiator so that the object does not soften and deform during the heating. Thermoset polymers on the other hand can most often withstand elevated temperatures better and then a wider temperature range can be utilized. The lower temperature limit is determined by the thermal initiator so that the thermal initiator decomposes to a radical at the temperature. The upper temperature limit is most often determined by the object to be treated so that the object is not destroyed or adversely affected by the temperature. This gives a temperature window when a suitable thermal initiator is selected depending on the material in the object.

In one embodiment, the object is heated until it has essentially the same temperature throughout the entire object. A short heating time may result in that the object is warm on the surface and close to the surface, but has a lower temperature inside. In one embodiment, it is desired that the object is heated so that its heat storage is maximized, which occurs when it is heated throughout its volume. In one embodiment, a slight temperature variation is tolerated between the surface and the inside of the object. In one embodiment, the object is heated in a convection oven for 30 minutes. The quick heating of the solution with heat from the object gives a high concentration of radicals and a quick release of radicals. This gives an efficient initiation and is much more efficient compared to heating the object together with the applied solution, which would give a much slower release of radicals over a longer time. The high concentration of radicals makes the process less prone to disturbance from oxygen. When the radical concentration is high, dissolved oxygen in the solution will be consumed by the radicals and still the remaining radicals will be able to initiate polymerization and grafting. This is opposed to the situation where the object is heated together with the applied solution, then the radicals will be released at a slower pace and giving rise to lower concentration of radicals which to a large extent will be consumed by oxygen so that the initiation will be less efficient. In the latter case additional oxygen will also be able to diffuse into the solution since the process is much slower.

The heating of the applied solution is independent of the geometry of the object as long as the solution can be applied in a suitable thickness. The initiation is not dependent on UV-irradiation or other actinic irradiation and thus cavities can be coated as long as it is possible to apply the solution in contact with the object.

The solution is In one embodiment, applied in a thin layer such as for instance 10-5000 pm. The layer of applied solution is heated with heat from the object. This give maximum heating in the solution closest to the surface, which is desired. Thereby maximum concentration of radicals is achieved closest to the surface and this gives more points where the polymerizable molecule is covalently bound to the surface. Thus a higher density of covalently bound polymers can be created on the surface by using this method.

In the applied solution some degree of polymerization and formation of non-covalent polymers can occur. Such polymerization is not desired and polymers which are not covalently bound are In one embodiment, washed away after step b). Since the heat dissipates from the object into the applied solution the part of the applied solution closest to the object surface is heated first and to a greater extent, and this favours formation of covalent bonds to the surface compared to polymerization in the bulk of non- covalently bound polymers.

In one embodiment, the polymerizable molecules covalently bound to the surface of the object in step b) are further reacted with the polymerizable molecules during step b) to obtain polymer chains covalently bound to the surface of the object. The polymerization reaction can thus propagate so that covalently bound polymer chains are created, grafted to the surface. The relation between polymerizable molecule and initiator in the solution controls the chain length. Also the reaction time can to some extent affect the chain length.

In one embodiment, the at least one organic molecule is at least one selected from a monomer, an oligomer and a polymer. The organic molecules are contacted with the polymerizable molecules covalently bound to the object. The organic molecules are In one embodiment, bound to the polymerizable molecules. The polymerizable molecules can be a polymer chain or a smaller molecule. The organic molecules and the polymerizable molecules can be bound by different mechanisms, where examples include but are not limited to electrostatic, dipole-dipole, van der Waals forces and covalent bonds as well as combinations thereof. If both the polymerizable molecules and the organic molecules are polymers, then the binding can be by an interpenetrating polymer network.

In one embodiment, the object is made with injection molding, and wherein the remaining heat after the injection molding is utilized at least partially as heat for step a). During injection molding a polymer is heated and injected into a mold. When the object is released from the mold it is still hot and this heat can be utilized so that the object is transferred from the injection molding directly to the treatment according to the invention without unnecessary delay. If the heat is not sufficient additional heating can be performed.

In one embodiment, the object comprises a thermosetting polymer and the remaining heat after the curing is utilized at least partially as heat for step a). A thermosetting polymer is cured by applying heat and directly after the curing the object can be treated according to the invention without unnecessary delay. If the heat is not sufficient additional heating can be performed.

In one embodiment, the abstractable hydrogen atom is a hydrogen atom in at least one selected from a urethane group, an amine group, a thiol group, a hydroxyl group, a methyl group, and a methylene group. Combinations of different types of abstractable hydrogen atoms are also encompassed .

In one embodiment, the object is heated in step a) in a convection oven. In one embodiment, the object is heated in an owen. In one embodiment, the object is heated in step a) with IR- irradiation. In one embodiment, the object is heated in step a) by microwaves. In one embodiment, the object is heated in step a) by laser-irradiation. Combinations of different heating methods are also possible, such as for instance heating by microwaves and IR-irradiation.

In one embodiment, the object is heated in a desired pattern and/or on desired parts so that the coating only occurs at the desired heated parts. By such a method it is possible to coat a part of an object or to make a pattern on an object.

In one embodiment, the object is heated a second time with IR-irradiation immediately before step b). After a first heating by any method it is possible to heat the object again just before it is contacted with the solution. In one embodiment, the solution is contacted with the object no more than 5 seconds after a final heating. In one embodiment, it may not be possible to apply the solution immediately after a first heating for some reason. In such a case a second heating can be performed immediately before the solution is applied so that the object has the desired temperature when it contacts the surface. Such a second heating is conveniently carried out with IR-irradiation. For instance, an IR-lamp can easily be placed in a process line just before a step where the solution is applied on the heated object. Then the object will get a bit of additional heating just before the coating of the grafting solution. In an alternative embodiment such an IR irradiation is the only heating step.

After application of the solution any further heating would generally not be desired, since the heat dissipating form the object to the solution heats the solution closest to the object as desired. Further heating after application of the solution would not have this effect.

In one embodiment, a second object is heated and held in thermal contact with the object during step b). Such a second object is In one embodiment, made of a material with good thermal conductivity such as a metal. If the object to be coated is thin the heat may dissipate quickly, in such an embodiment another object can be heated and placed in thermal contact with the object during step b). Then heat will be transferred from the second object to the object. The shape of such a second object is preferably adapted to the shape of the object for best heat transfer.

The solution is transferred to the object by any suitable method as known in the art. In one embodiment, the at least a part of the surface of the object is contacted with the solution by at least one of the methods selected from the group consisting of spray, inkjet, wire bar applicator, padprint, curtain coating, brush, rolling, and dipping. The skilled person realizes that also other additives can be added to the solution, such as for instance rheology modifiers. The different application method may require the viscosity of the solution to be adjusted and this can be made by adding an additive.

In one embodiment, the molecules covalently bound to the surface of the object in step b) are charged.

In one embodiment, the thermal initiator is at least one selected from the group consisting of peroxides and azo compounds.

In one embodiment, the polymerizable molecule is at least one organic acid, hydroxyl, amine, thiol, oxirane, isocyanate and other reactive functional groups. In one embodiment, the at least one organic molecule in step c) is at least one selected from an adhesive, a coating, a top-coat, and an elastomer. Examples of organic molecules include rubber, polymers and combinations thereof. In one embodiment, the coating comprises a binder and optional pigment.

In one embodiment, at least a part of the surface of the object is treated with plasma comprising oxygen before step b). This has the effect of further improving the adhesion to Teflon® (polytetraflourethene). Such plasma treatment is conducted at any point before step b).

In one embodiment, the at least one organic molecule is a nitrile butadiene rubber (NPR). By using this method a rubber can be attached to a surface with high adhesion.

In one embodiment, a curing agent comprising sulphur is added in or after step c). Rubbers such as NPR can suitably be curing with a curing agent comprising sulphur.

Examples

Example 1:

A panel of carbon black filled TPO material(Thermo Plastic Olefin) was treated as described below:

A grafting resin solution consisting of acrylic acid (10.0 weight-%), 4,4 ^' -Azobis(4-cyanovaleric acid) (0.1 weight-%), ethanol (85 weight-%) and one component urethane resin (5 weight-%) was prepared.

The panels were heated in a convection owen for 30 minutes in 100 °C. Immediately before application of the solution they were heated with an IR-lamp with 200 W for 10 seconds. The time from the end of the last IR-irradiation to the contacting of the solution was 3-5 seconds.

The solution was sprayed by an air spray gun to TPO panels of 8 x 16 cm size. The wet film thickness was 45 to 75 pm.

The grafted surface was washed with a 70 % ethanol in water .

A one component PUR automotive primer was applied by spraying .

The adhesion of a PUR automotive primer was tested with a cross hatch method with tape. The untreated surface coated with the one component PUR automotive primer had 10 % of adhesion. The grafted surface coated with the one component PUR automotive primer had 100 % of adhesion .

Example 2:

A clear transparent COC material (Cyclic Olefinic Coploymer) was treated as described below:

A grafting solution consisting of 2-hydroxy ethylacrylate / methacrylic acid (20 / 30 weight-%), a, '-Azoisobutyronitrile (AIBN) (0.6 weight-%), cyclohexane and a polyester oligomer resin (10 weight- %) was prepared.

The panels were heated in a convection owen for 30 minutes in 125 °C. Immediately before application of the solution they were heated with an IR-lamp with 200 W for 5 seconds. The time from the end of the last IR-irradiation to the contacting of the solution was 3-5 seconds. The solution was sprayed by an air spray gun to COC panels of 10 x 10 cm size. The wet film thickness was 40 to 60 pm.

The grafted surface was washed with a 70 % ethanol in water .

The adhesion of a polyester lacquer was tested with a cross hatch method with tape. The untreated surface had 10 % of adhesion. The grafted and polyester lacquer coated panel had 100 % of adhesion.

Example 3:

A Polyamide 6 (PA6) material was treated as described below :

A grafting solution consisting of glycidyl methacrylate / ethyl acrylate (30 / 25 weight-%), a,a'-

Azoisobutyronitrile (AIBN) (0.9 weight-%) and ethanol was prepared.

The panels were heated in a microwave owen for 3 minutes reaching a surface temperature of 115 °C. The time to the contacting of the solution was 3-5 seconds.

The PA6 panels of 5 x 10 cm size were dipped in the solution. The wet film thickness was 200 to 400 pm.

The grafted surface was washed with an ethanol / ethylacetate (1 / 1) solution.

In the next step were 2 samples glued together with a commercial one component PUR adhesive.

The adhesion of the one component PUR adhesive was tested with an Instron tensile testing machine. The untreated surface had 8 N of adhesion and the grafted surface had 26 N of adhesion. Example 4:

A PUR material (polyurethane) was treated as described below :

A grafting solution consisting of glycidyl methacrylate / ethyl acrylate (35 / 15 weight-%), Dicumyl peroxide

(1.0 weight-%) and isopropanol was prepared.

The panels were heated in a microwave owen for 2.5 minutes reaching a surface temperature of 110 °C. The time to the contacting of the solution was 3-5 seconds.

The PUR panels panels of 6 x 6 cm size were curtain coated. The wet film thickness was 150 to 400 pm.

The grafted surface was washed with an ethanol / ethylacetate (1 / 1) solution.

In the next step were 2 samples glued together with a commercial one component Acrylic adhesive.

The adhesion of the one component Acrylic adhesive was tested with an Instron tensile testing machine. The untreated surface had 9 N of adhesion and the grafted surface had 31 N of adhesion.

Example 5:

A PUR material (polyurethane) was treated as described below :

A grafting solution consisting of glycidyl methacrylate / ethyl acrylate (35 / 15 weight-%), Bensoyl peroxide

(1.2 weight-%) and isopropanol was prepared.

The panels were heated in a microwave owen for 3.0 minutes reaching a surface temperature of 110 °C. The time to the contacting of the solution was 3-5 seconds.

The PUR panels panels of 6 x 6 cm size were spray coated. The wet film thickness was 50 to 70 pm. The grafted surface was washed with an isopropanol / ethanol (1 / 1) solution.

In the next step were 2 samples glued together with a commercial one component Acrylic adhesive.

The adhesion of the one component Acrylic adhesive was tested with an Instron tensile testing machine. The untreated surface had 8 N of adhesion and the grafted surface had 36 N of adhesion.

Example 6.

A panel of glass fibre filled epoxy (Thermoset material) was treated as described below:

A grafting resin solution consisting of THIOCURE® TMPMP (thiol)(12 weight-%), 4,4 -Azobis(4-cyanovaleric acid) (0.4 weight-%), ethanol (53 weight-%) and one component urethane resin (35 weight-%)was prepared.

The panels were heated in a convection owen for 20 minutes in 130 °C. The time to the contacting of the grafting solution was 3-5 seconds.

The grafting solution was sprayed by an air spray gun to glass fibre filled epoxy panels of 10 x 10 cm size. The wet film thickness was 50 to 70 pm.

The grafted surface was washed with a 70 % ethanol.

A one component PUR automotive primer was applied by spraying .

The adhesion of a PUR automotive primer was tested with a cross hatch method with tape. The untreated surface coated with the one component PUR automotive primer had 10 % of adhesion. The grafted surface coated with the one component PUR automotive primer had 100 % of adhesion .

Example 7.

A ABS material (Acrylonitrile butadiene styrene) was treated as described below:

A grafting solution consisting of glycidyl methacrylate / ethyl acrylate (35 / 15 weight-%), polyester oligomer (5 weight-%), Bensoyl peroxide (1.2 weight-%) and isopropanol was prepared.

The ABS panels were injection moulded reaching a surface temperature of 90 to 100 °C at the time when the grafting solution was applied.

The injection moulded ABS panels of 6 x 12 cm size were spray coated. The wet film thickness was 50 to 70 pm. The grafted surface was washed with an isopropanol / ethanol (1 / 1) solution.

In the next step were 2 ABS samples glued together with a commercial one component Acrylic adhesive.

The adhesion of the one component Acrylic adhesive was tested with an Instron tensile testing machine. The untreated surface had 5 N of adhesion and the grafted surface had 19 N of adhesion.

Example 8:

A clear transparent COC material (Cyclic Olefinic Coploymer) was treated with corona, flame, chlorinated olefin and grafting solution. A comparison between different methods are described in figure: A grafting solution consisting of glycidyl methacrylate / ethyl acrylate (35 / 15 weight-%), polyester oligomer (5 weight-%), Bensoyl peroxide (1.2 weight-%) and isopropanol was prepared.

The panels were heated in by a IR 300 W lamp for 30 seconds reaching 100 °C in surface temperature. The time to the contacting of the grafting solution was 3-5 seconds.

The grafting solution was sprayed by an air spray gun to the clear transparent COC material of 8 x 8 cm size. The wet film thickness was 50 to 70 pm.

The grafted surface was washed with a 70 % ethanol.

In the next step were the samples coated with a commercial two component PUR automotive primer for spoilers. The cross-hatch test gave the following results :

Un-treated panel 10 %

Flame treated panel 45 %

Corona treated panel 50 %

Chlorinated olefin panel 75 %

Grafted panel 100 %

Example 9:

Transparent polyester films have been treated with corona, flame, chlorinated olefin and grafting solution. A comparison between different methods are described in figure :

A grafting solution consisting of 2-hydroxy ethylacrylate / methacrylic acid (20 / 30 weight-%), a, '-Azoisobutyronitrile (AIBN) (0.6 weight-%), cyclohexane and a polyester oligomer resin (10 weight- %) was prepared. The panels were heated in a convection owen for 5 minutes in 110 °C. Immediately before application of the solution they were heated with an IR-lamp with 200 W for 10 seconds. The time from the end of the last IR-irradiation to the contacting of the solution was 3-5 seconds.

The solution was sprayed by an air spray gun to transparent polyester films. The wet film thickness was 30 to 40 pm.

The grafted surface was washed with a 70 % ethanol in water .

In the next step were the samples coated with a commercial cyanoacrylic adhesive and glued together.

The grafted samples had 260 % higher adhesion compared to non-treated reference polyester films.

Un-treated film 100 % (reference value)

Flame treated film 150 %

Corona treated film 170 %

Chlorinated olefin film 120 %

Grafted film 260 %

Example 10

A carbon black filled Polyamide 6 (PA6) material was treated as described below:

A grafting solution consisting of Trimethylolpropane Tri (3-mercaptopropionate )/ ethyl acrylate (15 / 10 weight-%), polyester oligomer resin (10 weight-%) 4,4 ^' - Azobis (4-cyanovaleric acid) (0.4 weight-%) and ethanol was prepared.

The panels were heated in a convection owen for 20 minutes in 110 °C. Immediately before application of the solution they were heated with an IR-lamp with 200 W for 10 seconds. The time from the end of the last IR-irradiation to the contacting of the solution was 3-5 seconds. The solution was sprayed by an air spray gun to carbon black filled PA6 panel. The wet film thickness was 40 to 60 pm.

The grafted surface was washed with a 70 % ethanol / isopropanol (1 / 1).

In the next step were the panels pressed with a commercial NBR rubber curing with sulphur at 180 °C for 10 minutes.

The adhesion of the commercial NBR rubber was tested with a non-treated carbon black filled Polyamide 6 material. The untreated surface had 120 % lower adhesion then the grafted surface.

Example 11:

A PTFE (Teflon) material has been treated as described below:

A grafting solution consisting of Trimethylolpropane 20 Tri (3-mercaptopropionate)/ ethyl acrylate (15/ lOweight- %), polyester oligomer resin (10 weight-%) 4,4 ^' -Azobis(4- cyanovaleric acid) (0,4weight-%) and ethanol was prepared. The panels were heated in a convection owen for 20-25 minutes in 110 °C.

The solution was sprayed by an air spray gun to PTFE (Teflon) material panel. The wet film thickness was 40 to 60pm. The grafted surface was washed with a 70 % ethanol / isopropanol (1 / 1).

In the next step were the panels pressed with a commercial NBR rubber curing with sulphur at 180 °C for 10 minutes. The adhesion of the commercial NBR rubber was tested with a non-treated PTFE (Teflon) material. The grafted surface had 420 % higher adhesion then the untreated surface.

Example 12: A PTFE (Teflon) material filled with 30 % glass fibre has been treated as described below:

A grafting solution consisting of Trimethylolpropane 20 Tri (3-mercaptopropionate)/ ethyl acrylate (15/ lOweight- %), polyester oligomer resin (10 weight-%) 4,4 ^' -Azobis(4- cyanovaleric acid) (0,4weight-%) and ethanol was prepared. The panels were heated in a convection owen for 20 - 25 minutes in 110 °C.

The solution was sprayed by an air spray gun to PTFE (Teflon) material filled with 30 % glass fibre panel. The wet film thickness was 40 to 60pm. The grafted surface was washed with a 70 % ethanol / isopropanol (1 / 1).

In the next step were the panels pressed with a commercial NBR rubber curing with sulphur at 180 °C for 10 minutes. The adhesion of the commercial NBR rubber was tested with a non-treated TPFE (Teflon) material filled with 30 % glass fibre. The grafted surface had 635 % higher adhesion then the untreated surface.

Example 13:

A PTFE (Teflon) material has been treated as described below:

The PTFE (Teflon) material was first oxygen plasma treated, treated in a Diener Electronic, Gmbh, Germany plasma equipment (24 litre plasma reactor Nano), with 100 % oxygen flow at 0.3 mbar for 5 minutes.

A grafting solution consisting of Trimethylolpropane 20 Tri (3-mercaptopropionate)/ ethyl acrylate (15/ lOweight- %), polyester oligomer resin (10 weight-%) 4,4 ^' -Azobis(4- cyanovaleric acid) (0,4weight-%) and ethanol was prepared. The panels were heated in a convection owen for 20 - 25 minutes in 110 °C. The solution was sprayed by an air spray gun to PTFE (Teflon) material panel. The wet film thickness was 40 to 60 pm. The grafted surface was washed with a 70 % ethanol / isopropanol (1 / 1).

In the next step were the panels pressed with a commercial NBR rubber curing with sulphur at 180 °C for 10 minutes. The adhesion of the commercial NBR rubber was tested with a non-treated PTFE (Teflon) material. The grafted surface had 740 % higher adhesion then the untreated surface.

Example 14:

A PTFE (Teflon) material filled with 30 % glass fibre has been treated as described below:

The PTFE (Teflon) material filled with 30 % glass fibre was first oxygen plasma treated in a Diener Electronic, Gmbh, Germany plasma equipment (24 litre plasma reactor Nano), with 100 % oxygen flow at 0.3 mbar for 5 minutes. A grafting solution consisting of Trimethylolpropane 20 Tri(3- mercaptopropionate)/ ethyl acrylate (15/ 10weight-%), polyester oligomer resin (10 weight-%) 4,4 ^' -Azobis(4- cyanovaleric acid) (0,4weight-%) and ethanol was prepared. The panels were heated in a convection owen for 20 25 minutes in 110 °C.

The solution was sprayed by an air spray gun to PTFE (Teflon) material filled with 30 % glass fibre panel. The wet film thickness was 40 to 60pm. The grafted surface was washed with a 70 % ethanol / isopropanol (1 / 1).

In the next step were the panels pressed with a commercial NBR rubber curing with sulphur at 180 °C for 10 minutes. The adhesion of the commercial NBR rubber was tested with a non-treated TPFE (Teflon) material filled with 30 % glass fibre. The grafted surface had 964 % higher adhesion then the untreated surface.

Example 15:

A PTFE (Teflon) material filled with 30 % glass fibre has been treated as described below:

The panels have been treated with oxygen plasma, flame, grafting solution and oxygen plasma in combination with grafting solution. A comparison between the different methods is described below:

A grafting solution consisting of glycidyl methacrylate / ethyl acrylate (35 / 15 weight -%), 25 polyester oligomer (5 weight -%), Bensoyl peroxide (1,2 weight - %), Bensophenone (1,5 weight-%)and isopropanol was prepared .

The grafting solution was sprayed by an air spray gun solution was sprayed by an air spray gun to the PTFE (Teflon) material filled with 30 % glass fibre of 8 x 8 cm size. The wet film thickness was 20 to 35 pm.

The panels were heated in by an IR 300 W lamp for 20 seconds reaching 90 °C in surface temperature. The time to the contacting of the grafting solution was 3-5 seconds .

After IR irradiation was the panels UV cured in a Fusion LED lamp equipment for 10 seconds.

The grafted surface was washed with a 70 % ethanol.

In the next step were the samples coated with a commercial two component PUR automotive primer for spoilers. The cross-hatch test gave the following hatch test gave the following adhesion results:

Un-treated panel: 0 % Flame treated panel: 10 % Oxygen plasma treated panel: 15 %

Grafting solution: 85 %

Oxygen plasma in combination with grafting solution: 100

%.