The invention relates to a display device with functional elements. The invention fur ther relates to a method for producing a display device with functional elements.

Display devices having functional elements which are illuminable by a light source that may be placed behind the display device are widely used in vehicles.

EP 1 034 965 B1 describes display units, having a display front, which is provided with signs having a transparent portion and a substantially opaque portion enclosed by the transparent portion, and which has a light source arranged behind the display front for illu mination in the transmitted light method.

The functional elements may be symbols that provide certain information content to the driver in specific situation, e.g. the refueling indicator. Hence there is the need that these functional elements should only be visible to the driver in the specific situation, e.g. if the fuel tank reaches a critical filling level. However, in cases when there are several functional elements on the display device there may be stray light contamination of neighboring func tional elements. Hence, not only the functional element that shall be illuminated is visible for the user but also the neighboring functional element.

Furthermore, many car manufacturers manufacture their vehicles with full equipment independent of the specific model in the model range, as this is cheaper than equipping ve hicles individually for each model in the model range. These equipment parts may be acti vated at a later date for a fee. In order for this to go unnoticed by the customer, light con tamination of non-activated functional elements should be avoided.

In view of the aforementioned prior art, it is an object of the invention to provide means for reducing light scattering between separate arranged functional elements.

According to the invention a solution for this problem is achieved by a display device having the features of independent claim 1. Preferred embodiments are defined by the fea tures of the dependent claims.

Furthermore, this object is solved by the method for producing the above display de vice having the features of independent claim 25. Preferred embodiments are defined by the features of the dependent claims.

Provided is a display device with illuminable functional elements comprising: at least one functional layer, at least one rear support layer, and at least one light barrier element, wherein the functional layer is next to the rear support layer, wherein an upper surface of the rear support layer is opposite to a lower surface of the rear support layer and contacts a lower surface of the functional layer, wherein the functional layer comprises at least two functional elements, that are light transmittance for visible light and are illuminable by at least one light source, wherein the rear support layer is light transmittance for visible light, the rear support layer comprises at least one light barrier element, wherein the light barrier element comprises a dye and is formed in the rear support layer, such that the dye is molecularly solved in the material of the rear support layer, wherein the light barrier element extends essentially ver tically - i.e. with an angle of 90° +/- 50% - from the lower surface of the rear support layer into the rear support layer and is arranged between of at least two superposed functional elements of the superposed functional layer, wherein the light barrier element arrange in the rear support layer at least partly surrounds spaced apart at least one superposed functional element, and wherein the light barrier element is adapted for reducing or preventing light scattering through the light barrier element.

The light barrier element comprises the dye. The term “dye” means in the context of the invention a substance, preferably an organic substance, that is soluble in the material of the rear support layer. Accordingly, the dye-molecules primarily exists in the material of the rear support layer as molecularly solved dye-molecules. Preferably, at least more than 90% of the dye-molecules are molecularly solved in the material of the rear support layer. In contrast to dyes, pigments - organic or inorganic - would be present as finely distributed particles or agglomerates.

Furthermore, according to a preferred embodiment, the dye may have a molecular weight in the range of about > 250 g/mol to about < 1000 g/mol, preferably in the range of about > 250 g/mol to about < 550 g/mol. The dye may migrate into the rear support layer material forming the light barrier element.

According to one embodiment a display device with illuminable functional elements is provided comprising: at least one front layer, at least one functional layer, at least one rear support layer, and at least one light barrier element, wherein the functional layer is sand wiched between the front layer and the rear support layer, wherein an upper surface of the rear support layer is opposite to a lower surface of the rear support layer and contacts a lower surface of the functional layer, wherein an upper surface of the functional layer contacts a lower surface of the front layer, wherein the functional layer comprises at least two func tional elements, that are light transmittance for visible light and are illuminable by at least one light source, wherein the rear support layer is light transmittance for visible light, wherein the rear support layer comprises at least one light barrier element, wherein the light barrier element comprises a dye and is formed in the rear support layer, such that the dye is molecularly solved in the material of the rear support layer, wherein the light barrier element extends essentially vertically from the lower surface of the rear support layer into the rear support layer and is arranged between of at least two superposed functional elements of the superposed functional layer, wherein the light barrier element arranged in the rear support layer at least partly surrounds spaced apart at least one superposed functional element, and wherein the light barrier element is adapted for reducing or preventing light scattering through the light barrier element.

According to one embodiment a display device with illuminable functional elements is provided comprising: at least one front layer, at least one functional layer, at least one rear support layer, and at least one light barrier element, wherein the functional layer is sand wiched between the front layer and the rear support layer, wherein an upper surface of the rear support layer is opposite to a lower surface of the rear support layer and contacts a lower surface of the functional layer, wherein an upper surface of the functional layer contacts a lower surface of the front layer, wherein the functional layer comprises at least two func tional elements, that are light transmittance for visible light and are illuminable by at least one light source, wherein the front layer is of a transparent material so that the illuminable functional elements are visible through the front layer for a user when illuminated, wherein the rear support layer is light transmittance for visible light, wherein the rear support layer comprises at least one light barrier element, wherein the light barrier element comprises a dye and is formed in the rear support layer, such that the dye is molecularly solved in the material of the rear support layer, wherein the light barrier element extends essentially ver tically from the lower surface of the rear support layer into the rear support layer and is arranged between of at least two superposed functional elements of the superposed func tional layer, wherein the light barrier element arranged in the rear support layer at least partly surrounds spaced apart at least one superposed functional element, and wherein the light barrier element is adapted for reducing or preventing light scattering through the light barrier element.

According to another embodiment a display device with illuminable functional ele ments is provided comprising: at least one front layer, at least one functional layer, at least one rear support layer, and at least one light barrier element, wherein the functional layer is sandwiched between the front layer and the rear support layer, wherein an upper surface of the rear support layer is opposite to a lower surface of the rear support layer and contacts a lower surface of the functional layer, wherein an upper surface of the functional layer con tacts a lower surface of the front layer, wherein the functional layer comprises at least two functional elements, that are light transmittance for visible light and are illuminable by at least one light source, wherein the front layer is of a transparent material so that the illumi nable functional elements are visible through the front layer for a user, wherein the rear support layer is light transmittance for visible light, wherein the rear support layer comprises at least one light barrier element, wherein the light barrier element comprises a dye and is formed in the rear support layer, such that the dye is molecularly solved in the material of the rear support layer, wherein the light barrier element extends essentially vertically from the lower surface of the rear support layer into the rear support layer and is arranged between of at least two superposed functional elements of the superposed functional layer, wherein the light barrier element arranged in the rear support layer at least partly surrounds spaced apart the at least one superposed functional element, wherein the light barrier element com prises the dye having a molecular weight in the range of about > 250 g/mol to about < 1000 g/mol, and wherein the light barrier element is adapted for reducing or preventing light scat tering through the light barrier element.

The main idea is to have a display device with several layers -functional layer, rear support layer, and optionally a front layer - and to have a light barrier element, which com prises the dye, in the rear support layer. The functional elements in the functional layer are light transmittance for visible light and are illuminable by a light source. The functional elements and/or the functional layer may be colored. The term “functional element” means in the context of the invention a specific region of the functional layer that has a different light transmittance than the region of the functional layer surrounding the specific region of the functional layer. For example, the region of the functional layer surrounding the func tional element may have a different color than the functional element. Hence, during day the functional elements are easily visible due to the color difference. At night the functional elements may be illuminated to provide visibility without glare. Alternatively, the functional elements may appear to the user to have the same color as the region of the functional layer surrounding the functional elements. In this case, during day the user may not be aware of the existence of the functional element. However, even though the functional element ap pears to the user to have the same color as the region surrounding the functional element, the light transmittance of the functional element is preferably different compared to the light transmittance of the region of the functional layer surrounding the functional element. Hence, after activation of the functional element or after activation of a feature symbolized by the functional element, the functional element may get visible to the user due to illumi nation of the functional element. For illumination of the functional elements a light source may be installed behind the display device. Furthermore, the rear support layer is transparent, semi-transparent, or translucent for visible light to facilitate the illumination of the functional elements.

Even though it may be often the case that - from a perspective of a user of the display device - that the functional layer is the foremost layer or in case there is a front layer that the front layer is the foremost layer and that the rear support layer is - from the perspective of the user - behind the functional layer or front layer, it is also possible that the rear support layer is the foremost layer, and the functional layer and optionally front layer are behind the rear support layer.

Furthermore, it may also be the case, that the display device comprises additional lay ers. Furthermore, the additional layers may have a light barrier element or may be without a light barrier element.

As already mentioned, the functional element is a specific region of the functional layer that has a different light transmittance than the region of the functional layer surround ing the specific region of the functional layer. The functional element may be generated by using different coloring agents for the specific region of the functional layer than for the rest of the functional layer. The functional element may have the form of a symbol or a letter to provide certain information content to the driver in specific situation, for example the form of a refueling indicator. Preferably, the functional element may have a higher light transmit tance than the region of the functional layer surrounding the functional element. The func tional element itself may also include several regions having higher and/or lower light trans mittance than the region of the functional layer surrounding the functional element. More preferably, the region of the functional layer surrounding the functional element may have a light transmittance close to zero. In other words, the region of the functional layer surround ing the functional element may be optically dense.

The term “transparent” as well as “light transmittance” means in the context of the invention that the rear support layer has at least a light transmittance for visible light that is > 10 %, preferably > 50% and more preferably > 75%. Even more preferably, the rear sup port layer has at least a light transmittance for light with a wavelength between 380 nm to 750 nm that is > 10%, preferably > 50% and more preferably > 75%. Moreover, in the con text of the invention the term means that the front layer has at least a light transmittance for visible light that is > 10%, preferably > 50% and more preferably > 75%. Even more prefer ably, the rear support layer has at least a light transmittance for light with a wavelength between 380 nm to 750 nm that is > 10%, preferably > 50% and more preferably > 75%. To prevent or reduce stray light contamination of neighboring functional elements, the rear sup port layer comprises at least one light barrier element that is adapted for reducing or prevent ing light scattering through the light barrier element. Being adapted for reducing or prevent ing light scattering through the light barrier element may mean that the light barrier element absorbs or reflects light. In other words, the light barrier element is less light transmittance than the rear support layer. Preferably, the light barrier element has a low transmittance of light through the light barrier. More preferably the light barrier element has a light transmit tance for visible light that is < 75%, preferably < 10%. Even more preferably, the light barrier element has a light transmittance for light with a wavelength between 380 nm to 750 nm that that is < 25%, preferably < 10%.

Furthermore a display device may be provided, wherein the light transmission in the range of 380 nm to 750 nm of the light barrier element is at least 2 times, preferably at least 100 times less compared with the light transmission in the range of 380 nm to 750 nm of the rear support layer, based on the same path length.

The light transmittance for visible light for the rear support layer, the front layer and the light barrier element may be determined according to the DIN 1349 (Transmisson of optical radiation; optical clear (nonscattering) media, quantities, symbols and units). Prefer ably, the transmittance of the front layer and the rear support layer is determined with UV- VIS spectroscopy across a path length of 1 cm of the rear support layer and/or the front layer. More preferably, the transmittance of the light barrier element is determined with UV-VIS spectroscopy across a path length of 1 mm of the light barrier element. Further preferably, the wavelength for determining the transmittance is 532 nm, more preferably the wavelength for determining the transmittance corresponds to the wavelength of the light source used to illuminate the functional element.

The light barrier element is formed in the rear support layer and arranged in the rear support layer, such that it extends essentially vertically from the lower surface of the rear support layer into the rear support layer. Essentially vertically may mean that the light barrier element extends parallel to a normal vector of the lower surface into the lower surface. Fur ther, the light barrier element may extend more into the vertical direction as it extends into a direction perpendicular to the vertical direction. Further, the light barrier element may ex tend from the lower surface of the rear support layer into the rear support layer with an angle of 90° +/- 50%. Furthermore, the light barrier element may have a certain thickness orthog onal to its vertical extension. Preferably, the thickness of the light barrier element may be 1 , 1 to 10 times lower than a vertical extent of the light barrier element into rear support layer. The thickness of the light barrier element may be essentially constant, meaning it does vary for not more than +/- 25%. Alternatively, the thickness of the light barrier element may vary. For example, the thickness of the light barrier element near the upper surface of the rear support layer may be higher than the thickness of the light barrier element further away from the upper surface of the rear support layer or vice versa. Furthermore, the light barrier ele ment is arranged between of at least two superposed functional elements of the superposed functional layer and the light barrier element at least partly surrounds spaced apart the at least one superposed functional element for effective prevention of stray light contamination. Therefore, the display device has no or significant reduced light scattering between the sep arate arranged and illuminable functional elements.

For example, when the display device is viewed from the perspective of a user sitting in front of the front layer, the light barrier element may completely or partially surround the functional element. The light barrier element may have the form of a straight line in between the two functional elements. The light barrier element may also have the form of a circle, semi-circle or segment of a circle. The light barrier element may also have the form of a “H”, “U”, “I”, or “L”. Any other forms are possible. It may be possible that every functional element is surrounded or partially surrounded by a light barrier element. It may also be pos sible that one light barrier element may be formed as a grid, and in some or all of the cells of the grid there may be a functional element. Therefore, the light barrier element may also have the function of a light guide.

If the display device is viewed from a perspective orthogonal to the perspective of the user, such that the layered structure of the display device is apparent, the light barrier element extends basically vertically into the rear support layer and is arranged between two super posed functional elements of the superposed functional layer. It may be possible that the light barrier element extends such far into the rear support layer that its vertical extent es sentially corresponds to the thickness of the rear support layer. In other words, the light barrier element may reach through the rear support layer. It may also be possible that the vertical extent of the light barrier element is smaller than the thickness of the rear support layer. In this case the light barrier element extends essentially vertically from the lower sur face of the rear support layer into the rear support layer and may end in the rear support layer.

According to a preferred embodiment the display device may comprise at least one light source, wherein the light source is arranged below the rear support layer and is posi tioned below at least one functional element, such that light emitted by the light source sub stantially illuminates the at least one functional element or wherein the display device com prises at least one light source, wherein the light source is arranged above the functional layer, and/or in case the display device comprises a front layer above the front layer, and is positioned above at least one functional element, such that light emitted by the light source substantially illuminates the at least one functional element. The light source may emit a beam of light that may be directed towards the functional element. Due to the light barrier element in the display device, light scattering to another functional element is prevented or reduced.

With respect to an effective reduction or prevention of stray light contamination of neighboring functional elements, the light barrier element may absorb light in a wavelength that essentially corresponds to a wavelength of the light emitted by the light source or the light barrier element may reflect light in a wavelength that essentially corresponds to a wave length of the light emitted by the light source. In other words, there may be two ways to achieve an effective reduction or prevention of light scattering to another functional element. One possibility is to use a light barrier element that absorbs the light emitted by the light source. For example, a dyed light barrier element may be used. By using different dyes of the light barrier element, the wavelength range of light absorbed by the light barrier element may be adjusted to the wavelength range of the light emitted by the light source. Preferably a dark dye, for example black, may be used as dye for the light barrier element. More pref erably a light barrier element with a high absorption cross section may be used. The light absorbed by the light barrier element may be dissipated to heat. Alternatively, the light ab sorbed by the light barrier element may be transformed into light with a different wavelength and emitted. Another possibility is to use a light barrier element that reflects the light emitted by the light source. In this case, compared to an absorptive light barrier element, a light source with a lower luminous intensity may be used, since essentially none of the light is absorbed by the light barrier. In this case, the light barrier element may have the function of a light guide. Preferably, a light barrier element with a high scattering cross section may be used. In both cases the light barrier element reduced or prevents light from traveling through the light barrier element i.e. the light barrier element may have a higher extinction cross section than the rear support layer.

According to the above a display device may be provided, wherein the light barrier element is less translucent than the rear support layer, and/or the light barrier element ab sorbs more light in a wavelength that essentially corresponds to a wavelength of the light emitted by the light source compared to the rear support layer, and/or the light barrier ele ment reflects more light in a wavelength that essentially corresponds to a wavelength of the light emitted by the light source compared to the rear support layer.

It may also be possible that there is one light source or a view light sources arranged below the rear support layer or above the front layer and/or functional layer. However, ac cording to a preferred embodiment, the display device may comprise a light source for each functional element. In other words, there may be several light sources, i.e. one light source for each functional element. This embodiment may have the advantage that each functional element may be illuminated individually. This may enhance the freedom of design.

With respect to the light source, the light source may be an LED or OLED light source. These light sources may be low maintenance, may have a high lifetime and low operating costs. Furthermore, LEDs or OLEDs may only produce little waste heat, may be produced in many different forms and layouts, and are inexpensive. They also provide the advantage that the light emitted by LEDs or OLEDs may be narrow-band, meaning that only a small wavelength range may be present. Therefore, the matching of the absorption or reflection spectrum of the light barrier element and the emission spectrum of the light source may be facilitated.

The different layer of the display device may have different thicknesses. According to a preferred embodiment the thickness of the front layer may be > 25 pm to < 40000 pm, preferably > 50 pm to < 10000 pm, and more preferably > 250 pm to < 500 pm.

In this regard the thickness of the functional layer may be > 1 pm to < 350 pm, pref erably > 5 pm to < 200 pm, more preferably > 20 pm to < 100 pm.

Furthermore, the thickness of the rear support layer may be > 25 pm to < 40000 pm, preferably > 50 pm to < 20000 pm, more preferably in between > 500 pm to < 10000 pm. In order to reduce stray light contamination of neighboring functional elements even further the display device may comprise a protrusion element, wherein the protrusion ele ment extends out of the lower surface of the rear support layer and is arranged between of at least two superposed functional elements of the superposed functional layer. Preferably the protrusion element is arranged on the lower surface of the rear support layer and positioned on the light barrier element. When viewed from the user perspective the protrusion element may be formed according to the light barrier element. More preferably the protrusion ele ment may be in between two neighbouring light sources. The protrusion element may be formed of a polymer material. Furthermore, the protrusion element may be formed by an optically dense material. Therefore, the protrusion element may have a higher extinction coefficient than the rear support layer.

Furthermore, a display device may be provided, wherein the thickness of the light bar rier in the rear support layer is > 1 pm to < 10.000 pm, preferably > 10 pm to < 5.000 pm, more preferably in between > 50 pm to < 1.000 pm. These values may lead to a more effi cient reduction of stray light contamination.

Furthermore, a display device may be provided, wherein the vertical extent of the light barrier element extending vertically into the rear support layer is in between 0,0025% to 100% of the thickness of the rear support layer, and/or > 1 pm, preferably > 100 pm, and more preferably > 250 pm. These values may lead to a more efficient reduction of stray light contamination. Preferably, the thickness of the light barrier element may be 1,1 to 10 times lower than the vertical extent of the light barrier element into rear support layer.

The display device may be based on a plastic material. According to a preferred em bodiment the front layer may comprise a front-layer-support-layer-polymer or mixtures thereof selected from the group comprising polycarbonate (PC), polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polyethylene furanoate (PEF), glycolized or amor phous polyester, glycolized or amorphous polyethylene terephthalate (PET-G or A-PET), polytrimethylenterephthalet (PTT), polybutylenterephtalhat (PBT), poly(methyl methacry late) (PMMA), polypropylene (PP), polyvinyl chloride (PVC), cellulose triacetate (TCA), polyamide (PA), poly imide (PI) or polyethylene (PE), polyoxymethylene (POM), polysty rene (PS), polyurethane (PU), silicone and acrylonitrile butadiene styrene (ABS).

Preferably, the front layer may be of a light transmittance material, which is translucent and/or transparent for visible light. Therefore, the functional layer and/or the functional ele ments may be visible through the front layer for the user. However, the front layer may still be colored. The front layer may comprise additional components in order to enhance the UV-stability, the scratch resistance, and/or other properties. Furthermore, the front layer may comprise filling material.

The front layer, which is light transmittance, may be a plastic film used for film insert molding. The plastic film may be based on polycarbonate. Polycarbonates are a group of thermoplastic polymers. Polycarbonates may be strong and resistant and therefore, the front layer may protect the functional layer. Additionally, polycarbonates may be easily worked, molded, and thermoformed, therefore facilitating the production of the display device.

In a preferred embodiment the display device may comprises an anti-scratch layer on an upper surface of the front layer, on an upper surface of the functional layer or on the lower surface of the rear support layer. The anti-scratch layer may be a lacquer that enhances the lifetime of the display device and makes it more resistant to environmental impacts. Prefer ably, also the anti-scratch layer is transparent, semi-transparent, or translucent for visible light to allow the visibility of the functional elements for the user. However, it is still possible that the anti-scratch layer is colored. The anti-scratch layer may also be structured to achieve a certain haptic perception, and/or a certain visual appearance e.g. a gloss or haze. In this respect the anti-scratch layer may comprise an anti-scratch layer polymer or mixtures thereof selected from the group comprising acrylic resin, epoxy resins, and polyurethane. The anti scratch layer polymer may also be cross-linked, or may be cross-linked by exposing the anti scratch layer polymer to UV-light and/or heat.

According to a further embodiment the light barrier element and the rear support layer are a one-piece component. A one-piece component may indicate that the light barrier ele ment and the rear support layer are not two separate components. Instead the display device is designed such that the rear support layer contains the light barrier element.

In this context and according to a further embodiment the light barrier element and/or the rear support layer may be based on a rear support layer material, wherein the rear support layer material comprises the front-layer-support-layer-polymer or mixtures thereof.

According to the above, a display device may be provided, wherein the light barrier element and the rear support layer are of the same material, with the exception that the light barrier element comprises in addition the dye, so that the transmittance of the light barrier element for light having a wavelength of 380 nm to 750 nm is less than the transmittance of the rear support layer for light having a wavelength of 380 nm to 750 nm. Furthermore, the light barrier element and/or the rear support layer may comprise the front-layer-support-layer-polymer or mixtures thereof selected from the group comprising polycarbonate (PC), polyethylene terephthalate (PET), polyethylene naphthalate (PEN), pol yethylene furanoate (PEF), glycolized or amorphous polyester, glycolized or amorphous pol yethylene terephthalate (PET-G or A-PET), polytrimethylenterephthalet (PTT), poly- butylenterephtalhat (PBT), poly(methyl methacrylate) (PMMA), polypropylene (PP), poly vinyl chloride (PVC), cellulose triacetate (TCA), polyamide (PA), poly imide (PI) or poly ethylene (PE), polyoxymethylene (POM), polystyrene (PS), polyurethane (PU), silicone and acrylonitrile butadiene styrene (ABS).

According to a further embodiment the functional layer and/or the functional elements may be based on a functional layer material, wherein the functional layer material comprises a coloring agent or mixtures thereof. As already mentioned, the functional element is a spe cific region in the functional layer having a different light transmittance than the functional layer surrounding this specific region. The functional layer and/or the functional element may be based on the functional layer material. The functional layer and/or the functional element may be produced by printing the functional layer material on the front layer and/or on the rear support layer. Preferably a screen-printing process or an intaglio (printmaking) process, inmold labeling (IML) process, inmold decoration (IMD) process, or hot stamping process is used. The functional layer material may comprise the coloring agent or mixtures of different coloring agents. The coloring agents may be based on polyurethane and may be selected from the group comprising Noriphan HRT N, Noriphan HTR N HF, NoriPET, and Noricryl, delivered by the company Proll GmbH in Germany and/or coloring agents deliv ered by the company Teikoku Printing Inks Mfg. Co., Ltd in Japan. The coloring agent in the functional layer material is different from the dye in the light barrier element.

As already mentioned above the light barrier element and the rear support layer may be a one-piece component. Furthermore, it may be advantageous to produce the light barrier element by a colorization process of parts of the rear support layer leading to a migration of the dye into the rear support layer. There are various methods of coloring polar polymers such as polycarbonates and acrylonitrile-butadiene-styrene. However, these methods may not work, may not work efficiently, and/or are very slow for the generation of the light bar rier element and/or these methods may not work, may not work efficiently, and/or are very slow for the colorization of non-polar polymers, such as polyethylene (PE) and polypropyl ene (PP) or for mixtures that contain a substantial part of a non-polar polymer. Hence, according to the above, the rear support layer material may comprises at least 0.5 wt.-% of a front-layer-support-layer-polymer that has at least 5 wt.-% of heteroatoms based on the molecular weight of the front-layer-support-layer-polymer or mixtures thereof, wherein heteroatoms are any atoms except C and H atoms, or the rear support layer material may be based on a blend comprising > 0.5 wt.-% of a polar-compound or mixtures thereof and < 99.5 wt.-% of the front-layer-support-layer-polymer or mixtures thereof, and wherein the polar-compound has at least 5 wt.-% of heteroatoms based on the molecular weight of the polar-compound, wherein heteroatoms are any atoms except C and H atoms.

Furthermore, the light barrier element may comprise the dye and at least 0.5 wt.-% of the front-layer-support-layer-polymer that has at least 5 wt.-% of heteroatoms based on the molecular weight of the front-layer-support-layer-polymer or mixtures thereof, wherein heteroatoms are any atoms except C and H atoms, or the light barrier element may com prise the dye and may be based on a blend comprising > 0.5 wt.-% of a polar-compound or mixtures thereof and < 99.5 wt.-% of the front-layer-support-layer-polymer or mixtures thereof, and wherein the polar-compound has at least 5 wt.-% of heteroatoms based on the molecular weight of the polar-compound, wherein heteroatoms are any atoms except C and H atoms.

In order that the light barrier element may be formed, the rear support layer material may need to be polar. Therefore, it may comprise at least 0.5 wt.-% of the polar-compound. The polar-compound may be a synthetic polar-polymer, a synthetic polar-oligomer or a syn thetic polar-additive. The synthetic polar-polymer preferably has an Mw about > 1000 g/mol, the synthetic polar-oligomer preferably has an Mw about > 600 g/mol and < 1000 g/mol and the synthetic polar-additive preferably has an Mw about > 70 and < 600 g/mol. With regard to the polar-compound the polar-compound may have at least 5 wt.-% of heteroatoms based on the molecular weight of the polar-compound, wherein heteroatoms are any atoms except C and H atoms. Preferably the heteroatom is selected from the group comprising O, N, S, P, F, Cl, Br, and I. The polar-compound may be selected from the group comprising

Synthetic polar-polymer or mixture

The synthetic polar-polymer or mixture thereof may be selected from the group comprising:

- polyacrylate with methyl (polymethylacrylate), ethyl (polyethylacrylate), propyl (poly- propylacrylate), or butyl (polybutylacrylate), - polymethacrylate with methyl (polymethylmathacrylate), ethyl (polyethylmethacrylate), propyl (polypropylmethacrylate), or butyl (polybutylmethacrylate),

- copolymers of acrylic and methacrylic esters including, among others, /tvV- Butyl (meth)acrylate, pentyl(meth)acrylate and 2-ethylhexyl(meth)acrylate; (Meth)acrylates de rived from unsaturated alcohols, preferably oleyl(meth)acrylate, 2-propynyl(meth)acry- late, allyl(meth)acrylate, vinyl(meth)acrylate;

- aryl(meth)acrylates polymers, preferably benzyl(meth)acrylate polymers or phe- nyl(meth)acrylate polymers, the aryl radicals each being unsubstituted or up to four times substituted;

- cycloalkyl(meth)acrylates polymers, preferably 3-vinylcyclohexyl(meth)acrylate poly mers, bomyl (meth)acrylate polymers;

- hydroxylalkyl (meth)acrylates polymers, preferably 3- hydroxypropyl (meth)acrylate pol ymers, 3,4- dihydroxybutyl(meth)acrylate polymers, 2 -hydroxy ethyl(meth)acrylate poly mers, 2-hydroxypropyl(meth)acrylate polymers;

- glycol di(meth)acrylates polymers, preferably 1,4-butanediol (meth)acrylate polymers;

- (meth)acrylates of ether alcohols polymers, preferably tetrahydrofurfuryl (meth)acrylate polymers, vinyloxyethoxyethyl(meth)acrylate polymers;

- polymers of amides and nitriles of the (meth)acrylic acid, preferably N-(3-dimethyla- minopropyl)(meth)acrylamide polymers, N-(diethylphosphono)(meth)acrylamide poly mers, l-methacryloylamido-2-methyl-2-propanol polymers;

- polymers of sulfur-containing methacrylates, preferably ethylsulfmylethyl( meth)acrylate, 4-thiocyanatobutyl(meth)acrylate polymers, ethylsulfonylethyl(meth)acrylate polymers, thiocyanatomethyl(meth)acrylate polymers, methylsulfmylmethyl(meth)acrylate poly mers, bis((meth)acryloyloxyethyl)sulfide polymers;

- polyhydric (meth)acrylates, preferably trimethyloylpropanetri(meth)acrylate polymers;

- acrylonitrile polymers;

- vinyl ester polymers, preferably vinyl acetate polymers;

- styrene polymers, substituted styrenes polymers with an alkyl substituent in the side chain, preferably a-m ethyl styrene and a-ethyl styrene, substituted styrenes polymers with an alkyl substituent on the ring, preferably vinyl toluene, and p-m ethyl styrene, halogen- ated styrene polymers, preferably monochlorostyrene polymers, dichlorostyrene poly mers, tribromostyrene polymers and tetrabromostyrene polymers; - heterocyclic vinyl polymers, preferably 2-vinylpyridine polymers, 3-vinylpyridine poly mers, 2-methyl-5-vinylpyridine polymers, 3-ethyl-4-vinylpyridine polymers, 2,3-dime- thyl-5-vinylpyridine polymers, vinylpyrimidine polymers, vinylpiperidine polymers, 9- vinylcarbazole polymers, 3-vinylcarbazole polymers, 4-vinylcarbazole polymers, 1-vi- nylimidazole polymers, 2-methyl- 1-vinylimidazole polymers, N-vinylpyrrolidone poly mers, 2-vinylpyrrolidone polymers, N-vinylpyrrolidine polymers, 3-vinylpyrrolidine pol ymers, N-vinylcaprolactam polymers, N-vinylbutyrolactam polymers, vinyl oxolane pol ymers, vinyl furan polymers, vinyl thiophene polymers, vinylthiolane polymers, vinylthi- azoles and hydrogenated vinylthiazoles polymers, vinyloxazoles and hydrogenated vi- nyloxazoles;

- polymers of vinyl and isoprenyl ethers;

- maleic acid polymers, preferably maleic anhydride polymers, methyl maleic anhydride polymers, maleimide polymers, methyl maleimide;

- copolymers of ethylene and propylene with acrylic esters, preferably polyethylen-block- co-polymethylmethacrylat, polypropylen-block-co-polymethylmethacrylat;

- aliphatic and/or aromatic polyesters, preferably, hydroxyl-functional dendritic polyesters, polycaprolactone, polyethylenterephthalate (PET), polyethylene naphthalate (PEN), pol yethylene furanoate (PEF), polytrimethylenterephthalat (PTT), polybutylenterephthalat (PBT), glycolized polyglycolterephthaltat (G-PET), amorphous polyethylenterephthalat (A-PET), polyesters of terephthalic acid, polyspiro-diol-terephthalate, polypentaspirogly- col-terephthalate (PSG), polycyclohexylenedimethylene-terephthalate (PCT), Polyeth- ylenfuranoate (PEF), Polyethylennaphthylat, polyester based copolymer including a di- carboxylic acid-derived residue including a residue derived from an aromatic dicarbox- ylic acid and a diol-derived residue including a residue derived from 4-(hydroxyme- thyl)cyclohexylmethyl-4’-(hydroxymethyl)cyclohexane carboxylate, polyester based co polymer including a dicarboxylic acid-derived residue including a residue derived from an aromatic dicarboxylic acid and a diol-derived residue including a residue derived from 4,4-(oxybis(methylene)bis) cyclohexane methanol;

- polycarbonate (PC), 2,2-Bis-(4-hydroxyphenyl)-propan (Bisphenol A) polycarbonate, 2,2-Bis-(4-hydroxyphenyl)-butan (Bisphenol B) polycarbonate, l,l-Bis(4-hydroxy- phenyl)cyclohexan (Bisphenol C) polycarbonate, 2,2’-Methylendiphenol (Bisphenol F) polycarbonate, 2,2-Bis(3,5-dibrom-4-hydroxyphenyl)propan (Tetrabrombisphenol A) polycarbonate und 2,2-Bis(3,5-dimethyl-4-hydroxyphenyl)propan (Tetramethylbisphenol A) polycarbonate, bisphenol S polycarbonate, dihydroxydiphenylsulfid polycarbonate, tetramethylbisphenol A polycarbonate, l,l-Bis(4-hydroxyphenyl)-3,3,5-trimethylcyclo- hexane (BPTMC) polycarbonate, l,l,l-Tris(4-hydroxyphenyl)-ethane (THPE) polycar bonate;

- aliphatic polyamide (PA), preferably PA 6 based on polycaprolactam, PA 6.6 based on 6,6-hexamethylendiamin and adipic acid, PA 6.66 based on caprolactam, co-poymer of hexamethylendiamin and adipic acid, PA 66.610 based on hexamethylendiamin, copoly mer of adipic acid and sebaic acid, PA 4.6, PA10, PA 12 and PA copolymers;

- polyurethane (PU),

- polar-copolymere, maleic anhydride-olefin copolymer;

- polyalkylenoxide, polyalkylene block copolymer, propylenoxide-ethylenoxide copoly mer, (m)ethylene acrylate-maleic anhydride copolymer;

- polar-terpolymere, preferably reactive terpolymers of ethylene, acrylic ester and maleic anhydride, or ethylene, methacrylic ester and maleic anhydride, or ethylene, acrylic esters and glycidyl methacrylate, or ethylene, methacrylic esters and glycidyl methacrylate, or ethylene, (meth)acrylic esters and methyl (methyl(meth)acrylate), ethyl (ethy(meth)acry- late), propyl (propyl(meth)acrylate), or butyl (butyl(meth)acrylate), polyamide, polyester- polyamides, or butyl (butyl(meth)acrylate), polyether-polyamide copolymers;

- polar polymer blends, preferably polycarbonate/polyethylenterephthalat blends (PC/PET blends), polycarbonate/polybutyleneterephthalate blends (PC/PBT blends), blends of pol ycyclohexylene dimethylene terephthalate copolymer, blends of poly(butylene-adipate- terephthalate);

- polyacrylnitril and polyacrylnitril-copolymers, preferably poly acrylonitrile butadiene styrene (ABS), poly styrene-acrylonitrile;

- polystyrene and polystyrene copolymers, preferably styrene/butadiene co-polymer (SBR), poly styrene-isoprene-styrene (SIS), poly(glycidyl methacrylate) grafted sulfonamide based polystyrene resin with tertiary amine;

- ethylene-vinyl acetate;

- polyether, preferably polyethyleneglycol, polyethyleneglycol with at least one fatty acid coupled to the polyethyleneglycol, terminating functional groups such NEh-terminated polyethers;

- functionalized polyacrylamide polymers, copolymers and terpolymers, preferably poly(2- acrylamido-2-aminopropionicacid) (poly AMP A), poly(2-acrylamido-2-amino propane sulfonic acid), poly(N-isopropylacylamide (polyPNIPAM); poly (amidoamine-co-acrylic acid) copolymer, poly(N,N-dimethylacrylamide-co-sodium acrylate), poly(acrylamide- co-sodium acrylate)/poly(ethylene glycol) semi-IPN, poly(acrylamide-co-sodium 4-sty- renesulfonate), poly(acrylamide-co-sodium 4-styrenesulfonate)/poly(ethylene glycol) semi-IPN, poly(acrylamide-co-sodium methacrylate), poly(acrylamide-co-sodium meth- acrylate)/poly(ethylene glycol) semi-IPN, and/or poly(N-isopropylacrylamide-co-acrylic acid) andpoly(acrylamide-co-acrylic acid;

- poly(ether sulfones)/poly(ethyleneimine) (PES/PEI);

- polyvinylpyrrolidone, preferably poly(N-vinyl-2-pyrrolidone), poly(N-vinyl-2-pyrroli- done-co-acrylonitrile) treated with hydroxylamine-hydrochloride

- polyvinyl alcohol; and/or

- poly(l-naphthylamine)-camphorsulphonic acid.

Other synthetic polar-polymer of amorphous copolyester, which can be used are known under the tradename Akestra 90, 100 and 110. The above named synthetic polar- polymers may be used alone or in a mixture of two or more.

With regard to hydroxyl-functional dendritic polyesters that can be suitable used as a polar polymer, these molecules may be produced using polyalcohol cores, hydroxy acids and technology based on captive materials. The dendritic structures may be formed by polymerization of the particular core and 2,2-dimethylol propionic acid (Bis-MPA). The base products that may be obtained are hydroxyl-functional dendritic polyesters. They may be fully aliphatic and may consist only of tertiary ester bonds. They may provide excellent thermal and chemical resistance. Extensive branching also improves reactivity, lowers vis cosity and results in balanced mechanical properties. The hydroxyl-functional dendritic polyesters may be known under the trade name Boltom®. The following dendritic poly mers may be used as non-limiting examples: Boltom® H20 16 terminal hydroxyl groups, nominal molecular weight of 1750 g/mol, Boltom® H20046 terminal hydroxyl groups, nominal molecular weight of 3100 g/mol, Boltom® H311 23 terminal hydroxyl groups, nominal molecular weight of 5300 g/mol, Boltom® P500 Formulated bimodal product with terminal hydroxyl groups, nominal molecular weight 1800 g/mol, Boltom® PI 000 formulated bimodal product with terminal hydroxyl groups, nominal molecular weight 1500 g/mol, Boltorn® U3000 modified with unsaturated fatty acid, nominal molecular weight 6500 g/mol, Boltorn® W3000 modified with non-ionic groups and unsaturated fatty acid, nominal molecular weight 10000 g/mol. With regard to the polyester based copolymers that can be suitable used as a polar polymers, these may further include but not limited to a dicarboxylic acid-derived residue including a residue derived from an aromatic dicarboxylic acid and a diol-derived residue including a residue derived from 4-(hydroxymethyl)cyclohexylmethyl-4’-(hydroxyme- thyl)cyclohexane carboxylate represented by the following chemical formula 1 and a resi due derived from 4,4-(oxybis(methylene)bis) cyclohexane methanol represented by the fol lowing chemical formula 2.

The compounds of chemical formula 1 and 2 can be copolymerized with aromatic dicarboxylic acid may be one or more selected from a group consisting of terephthalic acid, dimethyl terephthalate, cyclic dicarboxylic acid, isophthalic acid, adipic acid, azelaic acid, naphthalene dicarboxylic acid, and succinic acid.

The diol-derived residue of the copolymers may further include a residue derived from one or more other diols selected from a group consisting of 1,4-cyclohexane dimetha nol, 1,2-propanediol, 1,3 -propanediol, 1,4-butanediol, 2, 2-dimethyl-l, 3 -propanediol, 1,6- hexanediol, 1,2-cyclohexanediol, 1,4-cyclohexanediol, 1,2-cyclohexane dimethanol, 1,3- cyclohexane dimethanol, 2,2-dimethylpropane-l,3-diol (neopentyl glycol), ethylene glycol, and di ethylene glycol. A content of the diol derived residues of the residue derived from 4- (hydroxymethyl)cyclohexylmethyl 4’-(hydroxymethyl)cyclohexane carboxylate, the resi due derived from 4,4-(oxybis(methylene)bis) cyclohexane methanol, and other diol-de- rived residues may be about 10 to 80 mol% based on 100 mol% of the dicarboxylic acid co-monomer.

The synthetic polar-polymer may also comprise the polyester based copolymers used in a mixture with polyethylene terephthalate (PET). The mixture may consist of 1 to 99 wt.-% of PET and 1 to 99 wt.-% of the polyester based copolymers, in order that both components add up to 100 wt.-%. Additionally, or alternatively the compounds according to chemical formulas 1 and 2 may be used as co-monomers together with a further diol- component, e.g. ethylene glycol, in the preparation of the polyester based copolymers.

The polyester based copolymer may be prepared by reacting the dicarboxylic acid including the aromatic dicarboxylic acid with the diol including 4-(hydroxymethyl)cyclo- hexylmethyl 4’-(hydroxymethyl)cyclohexane carboxylate represented by chemical formula

1 and 4,4-(oxybis(methylene)bis) cyclohexane methanol represented by chemical formula

2 to perform an esterification reaction and a polycondensation reaction. In this case, other diols such as 1,4-cyclohexane dimethanol, ethylene glycol, diethylene glycol, or the like, as described above may be further reacted, such that a polyester based copolymer further including other diol-derived residues may be prepared.

With regard to the polyether, these may comprise but not limited to compounds that contain at least one polyethyleneglycol moiety and at least one fatty acid moiety coupled to the poly ethyleneglycol moiety. The poly ethyleneglycol moiety may contain 10 to 25 eth yleneglycol repeating units. The fatty acid moieties may be saturated or unsaturated and may contain 10 to 30 carbon atoms, preferably 16 to 22 carbon atoms. Examples of these fatty acid moieties are oleate, laureate, stearate, palmitate and ricinoleate. A specific pre ferred example may be ethoxylated sorbitan ester.

The ethoxylated sorbitan ester comprises a sorbitan group which is substituted by four polyethylene glycol substituents. The ethoxylated sorbitan ester may preferably com prise 14 to 26 ethylene glycol repeating units, preferably 16 to 24 ethylene glycol repeating units, more preferably between 18 and 22 repeating units. At least one of the ethylene gly col substituents in the ethoxylated sorbitan ester is connected via an ester bond to a fatty acid moiety. Preferably, at least two of the ethylene glycol substituents in the ethoxylated sorbitan ester are connected via an ester bond to a fatty acid moiety; more preferably at least three of the ethylene glycol substituents are connected via an ester bond to a fatty acid moiety. The fatty acid moieties may be saturated or unsaturated and may contain 10 to 30 carbon atoms, preferably 16 to 22 carbon atoms.

Examples of these fatty acid moieties are oleate, laureate, stearate and palmitate. Most preferred are ethoxylated sorbitan esters comprising four polyethylene glycol substit uents and wherein the ester comprises between 18 and 22 ethylene glycol repeating units and wherein three of the ethylene glycol substituents are connected to oleate, laurate or stearate groups. Examples of ethoxylated sorbitan esters that can be used as polar-polymer are poly oxyethylene (20) sorbitane monolaurate, polyoxyethylene (20) sorbitane dilaurate, polyox yethylene (20) sorbitane trilaurate, polyoxyethylene (20) sorbitane mono-oleate, polyoxy ethylene (20) sorbitane di-oleate, polyoxyethylene (20) sorbitane tri-oleate, polyoxyeth ylene (20) sorbitane monostearate, polyoxyethylene (20) sorbitane distearate, polyoxyeth ylene (20) sorbitane tristearate, and polyoxyethylene (20) sorbitan monooleate, also known as Polysorbate 80 and E433.

Synthetic polar-oligomer and mixtures thereof

With respect to the synthetic polar-oligomer and according to another embodiment the synthetic polar-oligomer or mixture thereof may be selected from the group compris ing:

- oligoacrylate with methyl (oligomethylacrylate), ethyl (oligoethylacrylate), propyl (oli- gopropylacrylate), or butyl (oligobutylacrylate),

- oligomethacrylate with methyl (oligomethylmathacrylate), ethyl (oligoethylmethacry- late), propyl (oligopropylmethacrylate), or butyl (oligobutylmethacrylate),

- cooligomers of acrylic and methacrylic esters including, among others, tert. - Butyl (meth)acrylate, pentyl(meth)acrylate and 2-ethylhexyl(meth)acrylate; (Meth)acrylates de rived from unsaturated alcohols, preferably oleyl(meth)acrylate, 2-propynyl(meth)acry- late, allyl(meth)acrylate, vinyl(meth)acrylate;

- aryl(meth)acrylates oligomers, preferably benzyl(meth)acrylate oligomers or phe- nyl(meth)acrylate oligomers, the aryl radicals each being unsubstituted or up to four times substituted;

- cycloalkyl(meth)acrylates oligomers, preferably 3-vinylcyclohexyl(meth)acrylate oligo mers, bomyl (meth)acrylate oligomers;

- hydroxylalkyl (meth)acrylates oligomers, preferably 3- hydroxypropyl (meth)acrylate oli gomers, 3,4- dihydroxybutyl(meth)acrylate oligomers, 2 -hydroxy ethyl(meth)acrylate oli gomers, 2-hydroxypropyl(meth)acrylate oligomers;

- glycol di(meth)acrylates oligomers, preferably 1,4-butanediol (meth)acrylate oligomers;

- (meth)acrylates of ether alcohols oligomers, preferably tetrahydrofurfuryl (meth)acrylate oligomers, vinyloxyethoxyethyl(meth)acrylate oligomers; - oligomers of amides and nitriles of the (meth)acrylic acid, preferably N-(3-dimethyla- minopropyl)(meth)acrylamide oligomers, N-(diethylphosphono)(meth)acrylamide oligo mers, l-methacryloylamido-2-methyl-2-propanol oligomers;

- oligomers of sulfur-containing methacrylates, preferably ethylsulfmylethyl( methacry late, 4-thiocyanatobutyl(meth)acrylate oligomers, ethylsulfonylethyl(meth)acrylate oligo mers, thiocyanatomethyl(meth)acrylate oligomers, methylsulfmylmethyl(meth)acrylate oligomers, bis((meth)acryloyloxyethyl)sulfide oligomers;

- oligohydric (meth)acrylates, preferably trimethyloylpropanetri(meth)acrylate oligomers;

- acrylonitrile oligomers;

- vinyl ester oligomers, preferably vinyl acetate oligomers;

- styrene oligomers, substituted styrenes oligomers with an alkyl substituent in the side chain, preferably a-m ethyl styrene and a -ethyl styrene, substituted styrenes oligomers with an alkyl substituent on the ring, preferably vinyl toluene, and p-methyl styrene, halo- genated styrene oligomers, preferably monochlorostyrene oligomers, dichlorostyrene oli gomers, tribromostyrene oligomers and tetrabromostyrene oligomers;

- heterocyclic vinyl oligomers, preferably 2-vinylpyridine oligomers, 3-vinylpyridine oli gomers, 2-methyl-5-vinylpyridine oligomers, 3-ethyl-4-vinylpyridine oligomers, 2,3-di- methyl-5-vinylpyridine oligomers, vinylpyrimidine oligomers, vinylpiperidine oligomers, 9-vinylcarbazole oligomers, 3-vinylcarbazole oligomers, 4-vinylcarbazole oligomers, 1- vinylimidazole oligomers, 2-methyl- 1-vinylimidazole oligomers, N-vinylpyrrolidone oli gomers, 2-vinylpyrrolidone oligomers, N-vinylpyrrolidine oligomers, 3-vinylpyrrolidine oligomers, N-vinylcaprolactam oligomers, N-vinylbutyrolactam oligomers, vinyl oxolane oligomers, vinyl furan oligomers, vinyl thiophene oligomers, vinylthiolane oligomers, vi- nylthiazoles and hydrogenated vinylthiazoles oligomers, vinyloxazoles and hydrogenated vinyloxazoles;

- oligomers of vinyl and isoprenyl ethers;

- maleic acid oligomers, preferably maleic anhydride oligomers, methyl maleic anhydride oligomers, maleimide oligomers, methyl maleimide; and

- cooligomers of ethylene and propylene with acrylic esters, preferably oligoethylen-block- co-oligomethylmethacrylat, oligopropylen-block-co-oligomethylmethacrylat;

- aliphatic and/or aromatic oligoesters, preferably oligocaprolactone, oligoethylentereph- thalate (PET), oligoethylene naphthalate (PEN), oligoethylene furanoate (PEF), oligotri- methylenterephthalat (PTT), oligobutylenterephthalat (PBT), glycolized oligoglycolter- ephthaltat (G-PET), amorphes oligoethylenterephthalat (A-PET), oligoesters of tereph- thalic acid, oligospiro-diol-terephthalate, oligopentaspiroglycol-terephthalate (PSG), pol- ycyclohexylenedimethylene-terephthalate, Oligoethylenfuranoate (PEF), Oligoeth- ylennaphthylat, oligoester based cooligomer including a dicarboxylic acid-derived resi due including a residue derived from an aromatic dicarboxylic acid and a diol-derived residue including a residue derived from 4-(hydroxymethyl)cyclohexylmethyl-4’-(hy- droxymethyl)cyclohexane carboxylate, digester based cooligomer including a dicarbox ylic acid-derived residue including a residue derived from an aromatic dicarboxylic acid and a diol-derived residue including a residue derived from 4,4-(oxybis(methylene)bis) cyclohexane methanol;

- oligocarbonate (PC), 2,2-Bis-(4-hydroxyphenyl)-propan (Bisphenol A) oligocarbonate, 2,2-Bis-(4-hydroxyphenyl)-butan (Bisphenol B) oligocarbonate, l,l-Bis(4-hydroxy- phenyl)cyclohexan (Bisphenol C) oligocarbonate, 2,2’-Methylendiphenol (Bisphenol F) oligocarbonate, 2,2-Bis(3,5-dibrom-4-hydroxyphenyl)propan (Tetrabrombisphenol A) ol igocarbonate und 2,2-Bis(3,5-dimethyl-4-hydroxyphenyl)propan (Tetramethylbisphenol A) oligocarbonate, bisphenol S oligocarbonate, dihydroxydiphenylsulfid oligocarbonate, tetramethylbisphenol A oligocarbonate, l,l-Bis(4-hydroxyphenyl)-3,3,5-trimethylcyclo- hexane (BPTMC) oligocarbonate, l,l,l-Tris(4-hydroxyphenyl)-ethane (THPE) oligocar bonate;

- aliphatic oligoamide (PA), preferably PA 6 based on oligocaprolactam, PA 6.6 based on 6,6-hexamethylendiamin and adipic acid, PA 6.66 based on caprolactam, co-poymer of hexamethylendiamin and adipic acid, PA 66.610 based on hexamethylenediamine, cooli gomer of adipic acid and sebaic acid, PA 4.6, PA10, PA 12 and PA cooligomers;

- oligourethane (PU),

- polar-cooligomere, maleic anhydride-olefin cooligomer;

- oligoalkylenoxide, oligoalkylene block cooligomer, propylenoxide-ethylenoxide cooligo mer, (m)ethylene acrylate-maleic anhydride cooligomer;

- polar-teroligomere, preferably reactive teroligomers of ethylene, acrylic ester and maleic anhydride, or ethylene, methacrylic ester and maleic anhydride, or ethylene, acrylic esters and glycidyl methacrylate, or ethylene, methacrylic esters and glycidyl methacrylate, or ethylene, (meth)acrylic esters and methyl (methyl(meth)acrylate), ethyl (ethy(meth)acry- late), propyl (propyl(meth)acrylate), or butyl (butyl(meth)acrylate), oligoamide, oli- goester-oligoamides, or butyl (butyl(meth)acrylate), oligoether-oligoamide cooligomers;

- polar oligomer blends, preferably oligocarbonate/oligoethylenterephthalat blends (PC/PET blends), oligocarbonate/oligobutyleneterephthalate blends (PC/PBT blends), blends of oligocyclohexylene dimethylene terephthalate cooligomer, blends of oligo(bu- tylene-adipate- terephthalate);

- oligoacrylnitril and oligoacrylnitril-cooligomers, preferably oligo acrylonitrile butadiene styrene (ABS), oligo styrene-acrylonitrile;

- oligostyrene and oligostyrene cooligomers, preferably styrene/butadiene co-oligomer (SBR), oligo styrene-isoprene-styrene (SIS), oligo(glycidyl methacrylate) grafted sulfon amide based oligostyrene resin with tertiary amine;

- ethylene-vinyl acetate;

- fatty acids as Montanic acid and esters based on fatty acids;

- oligoether, preferably oligoethyleneglycol, oligoethyleneglycol with at least one fatty acid coupled to the oligoethyleneglycol, oligoether with terminating functional groups, preferbyl NEb-terminated oligoethers,

- functionalized oligoacrylamide oligomers, cooligomers and teroligomers, preferably ol- igo(2-acrylamido-2-aminopropionicacid) (oligoAMPA), oligo(2-acrylamido-2-amino propane sulfonic acid), oligo(N-isopropylacylamide (oligoPNIPAM); oligo (amidoamine- co-acrylic acid) co-oligomer, oligo(N,N-dimethylacrylamide-co-sodium acrylate), ol- igo(acrylamide-co-sodium acrylate)/oligo(ethylene glycol) semi-IPN, oligo(acrylamide- co-sodium 4-styrenesulfonate), oligo(acrylamide-co-sodium 4-styrenesulfonate)/ol- igo(ethylene glycol) semi-IPN, oligo(acrylamide-co-sodium methacrylate), oligo(acryla- mide-co-sodium methacrylate)/oligo(ethylene glycol) semi-IPN, and/or oligo(N-isoprop- ylacrylamide-co-acrylic acid) andoligo(acrylamide-co-acrylic acid;

- oligo(ether sulfones)/oligo(ethyleneimine) (PES/PEI);

- oligovinylpyrrolidone, preferably oligo(N-vinyl-2-pyrrolidone), oligo(N-vinyl-2-pyrroli- done-co-acrylonitrile) treated with hydroxylamine-hydrochloride

- oligovinyl alcohol;

- oligo(l-naphthylamine)-camphorsulphonic acid; and mixtures thereof.

With regard to the oligoester based cooligomers that can be suitable used as a polar oligomers, these may further include but not limited to a dicarboxylic acid-derived residue including a residue derived from an aromatic dicarboxylic acid and a diol-derived residue including a residue derived from 4-(hydroxymethyl)cyclohexylmethyl-4’-(hydroxyme- thyl)cyclohexane carboxylate represented by the following chemical formula 1 and a resi due derived from 4,4-(oxybis(methylene)bis) cyclohexane methanol represented by the fol lowing chemical formula 2.

The compounds of chemical formula 1 and 2 can be cooligomerized with aromatic dicarboxylic acid may be one or more selected from a group consisting of terephthalic acid, dimethyl terephthalate, cyclic dicarboxylic acid, isophthalic acid, adipic acid, azelaic acid, naphthalene dicarboxylic acid, and succinic acid.

The diol-derived residue of the cooligomers may further include a residue derived from one or more other diols selected from a group consisting of 1,4-cyclohexane dimetha nol, 1,2-propanediol, 1,3 -propanediol, 1,4-butanediol, 2, 2-dimethyl-l, 3 -propanediol, 1,6- hexanediol, 1,2-cyclohexanediol, 1,4-cyclohexanediol, 1,2-cyclohexane dimethanol, 1,3- cyclohexane dimethanol, 2,2-dimethylpropane-l,3-diol (neopentyl glycol), ethylene glycol, and di ethylene glycol. A content of the diol derived residues of the residue derived from 4- (hydroxymethyl)cyclohexylmethyl 4’-(hydroxymethyl)cyclohexane carboxylate, the resi due derived from 4,4-(oxybis(methylene)bis) cyclohexane methanol, and other diol-de- rived residues may be about 10 to 80 mol% based on 100 mol% of the dicarboxylic acid co-monomer.

The synthetic polar-oligomer may also comprise the oligoester based cooligomers used in a mixture with oligoethylene terephthalate (PET). The mixture may consist of 1 to 99 wt.-% of PET and 1 to 99 wt.-% of the oligoester based cooligomers, in order that both components add up to 100 wt.-%. Additionally or alternatively, the compounds according to chemical formulas 1 and 2 may be used as co-monomers together with a further diol- component, e.g. ethylene glycol, in the preparation of the oligoester based cooligomers. The oligoester based cooligomer may be prepared by reacting the dicarboxylic acid including the aromatic dicarboxylic acid with the diol including 4-(hydroxymethyl)cyclo- hexylmethyl 4’ -(hydroxymethyl )cyclohexane carboxylate represented by chemical formula

1 and 4,4-(oxybis(methylene)bis) cyclohexane methanol represented by chemical formula

2 to perform an esterification reaction and a oligocondensation reaction. In this case, other diols such as 1,4-cyclohexane dimethanol, ethylene glycol, diethylene glycol, or the like, as described above may be further reacted, such that a oligoester based cooligomer further including other diol-derived residues may be prepared.

With regard to the oligoether these may comprise but not limited to compounds that contains at least one oligoethyleneglycol moiety and at least one fatty acid moiety coupled to the oligoethyleneglycol moiety. The oligoethyleneglycol moiety may contain 8 or 9 eth yleneglycol repeating units.

The fatty acid moieties may be saturated or unsaturated and may contain 10 to 30 carbon atoms, preferably 16 to 22 carbon atoms.

Examples of these fatty acid moieties are oleate, laureate, stearate, palmitate and ricinoleate. Examples of compound that contain at least one polyethyleneglycol moiety and at least one fatty acid moiety coupled to the poly ethyleneglycol moiety include PEG 300 di-oleate, PEG 300-di stearate, PEG 400 dioleate, PEG 400 distearate, PEG 400 monoole- ate, PEG 400 monoricinoleate, PEG 400 monostearate.

A specific preferred example may be ethoxylated sorbitan oligoester. The ethox- ylated sorbitan oligoester comprises a sorbitan group which is substituted by four oligoeth- ylene glycol substituents. The ethoxylated sorbitan ester may preferably comprise 14 to 26 ethylene glycol repeating units, preferably 16 to 24 ethylene glycol repeating units, more preferably between 18 and 22 repeating units. At least one of the ethylene glycol substitu ents in the ethoxylated sorbitan ester is connected via an ester bond to a fatty acid moiety. Preferably, at least two of the ethylene glycol substituents in the ethoxylated sorbitan ester are connected via an ester bond to a fatty acid moiety; more preferably at least three of the ethylene glycol substituents are connected via an ester bond to a fatty acid moiety. The fatty acid moieties may be saturated or unsaturated and may contain 10 to 30 carbon atoms, preferably 16 to 22 carbon atoms.

Examples of these fatty acid moieties are oleate, laureate, stearate and palmitate. Most preferred are ethoxylated sorbitan esters comprising four oligoethylene glycol sub stituents and wherein the ester comprises between 18 and 22 ethylene glycol repeating units and wherein three of the ethylene glycol substituents are connected to oleate, laurate or stearate groups.

Synthetic polar-additive and mixtures thereof

The synthetic polar-additive may be solid at 23 °C. The synthetic polar-additive may not be the dye. The synthetic polar-additive may be solid at 23 °C and is not the dye.

In connection to the synthetic polar-additive and according to an another embodi ment the synthetic polar-additive having a Mw about > 70 and < 600 g/mol may be se lected from the group comprising aliphatic acids CTb-fCThJ _n -COOH acids (n about > 3), amino acids, carboxylic acid amide, hydroxyl acids, fatty acids, aliphatic or aliphatic/aro matic aldehydes and ketones, esters, pentaerythritol, pentaerythritol dimers, pentaerythritol trimers, pentaerythritol ester preferably carboxylic acid ester, benzoic acid esters compris ing benzylbenzoat or phenylbenzoat, phenylether, alcohols and polyvalent alcohols, prefer ably glycerine, amines, wherein the polar-additive is selected different the dye having a molecular weight Mw in the range of about > 250 g/mol to about < 550 g/mol; and prefera bly the polar-additive having a Mw about > 100 and < 600 g/mol is containing a heteroa tom selected from N, O, S and/or halogene. Preferably, halogens may be selected from the group comprising Cl, Br and I.

The carboxylic acid amide may comprise a compound according to formula C ₂ H ₄ (NHC(0)R ³ ) ₂ , wherein R ³ is a fatty acid moiety comprising 10-17 carbon atoms. The fatty acid moieties may be saturated or unsaturated. When the amount of carboxylic acid amide is too high the colored polar-polymer material may show blooming. Blooming i.e. discolorations may be caused by phase separation of the materiaTs components. It may be caused by incompatibilities of the polar-additive with the polar-polymer and/or with the polar-polymer material.

Pentaerythritol may comprise a compound according to formula CFhOR wherein R may be H, or wherein R may be a fatty acid moiety comprising 5-8 carbon at oms. The fatty acid moieties can be saturated or unsaturated. R may be also another moiety like ether, amide and/or urethane. As Pentaerythritol Perstorp Charmor PM 40 may be used.

Furthermore, the synthetic polar-additive may be an ether. Ether these may com prise but not limited to compounds that contains at least one ethyleneglycol moiety and at least one fatty acid moiety coupled to the ethyleneglycol moiety. Examples of compound that contains at least one ethyleneglycol moiety and at least one fatty acid moiety coupled to the poly ethyleneglycol moiety include PEG 300-monos tearate, PEG 400 monolaurate.

The carboxylic acid ester may comprise a compound according to the following chemical formula 3 : wherein R ¹ is an alkyl group comprising 1-20 carbon atoms and Z is hydrogen or a group according to the formula C(0)R ² , wherein R ² is an alkyl group comprising 1-20 carbon at oms. R ¹ may be the same or different and is an alkyl group comprising 1-20 carbon atoms, preferably 1-15 carbon atoms, more preferably 1-10 carbon atoms. R ² is an alkyl group comprising 1-20 carbon atoms, preferably 1-10 carbon atoms, more preferably 1-5 carbon atoms. Non-limiting examples of the carboxylic acid ester are tri ethyl citrate, tributyl citrate, trihexylcitrate, acetyltributylcitrate (ATBC; R ¹ = C ₄ H ₉ , Z = CH ₃ CO), propanoyltribu- tylcitrate, acetyltrihexylcitrate and butanoyltri ethyl citrate.

Furthermore, as synthetic polar-additive 4-(hydroxymethyl)cyclohexylmethyl-4’- (hydroxymethyl)cyclohexane carboxylate represented by the chemical formula 1, 4,4-(ox- ybis(methylene)bis) cyclohexane methanol represented by the chemical formula 2, and mixtures thereof may be used:

Furthermore, the light barrier element comprises the dye. Preferably the dye may have a molecular weight in the range of about > 250 g/mol to about < 1000 g/mol, preferably in the range of about > 250 g/mol to about < 550 g/mol. The dye may migrate into the rear support layer material forming the light barrier element. The dye preferably has a rather planar structure and preferably comprises at least one free rotation center outside the planar structure. Further in case of ligands and/or remnants which may be spatially or sterically demanding, the ligands and/or remnants may be as freely movable as possible around a cen- ter of rotation. Preferably the dye may not comprise a spiro-center and/or the dye may not comprise a large moiety that is rotation-impaired. In this context a large moiety that is rota tion impaired may mean that the molecular weight of this rotation impaired moiety is about 350 g/mol +/- 10%.

Furthermore, according to a preferred embodiment a display device may be provided, wherein the light barrier element comprises the dye in a concentration of about > 0,0001 wt.-% to < 5 wt.-%, based on the total weight of the light barrier element. This leads to a more efficient reduction of stray light contamination.

The dye may comprise at least 2 to 6 aromatic six-membered rings, or at least 3 to 5 aromatic six-membered rings and at least 1 to 4 five-membered rings. Furthermore, the dye may have at least 2 to 6 aromatic six-membered rings and/or the dye may comprise at least on heteroatom selected from N, O, S, Br.

Preferably the dye is selected from the group comprising the following chemical for mulas A1 to A10 according to table 1 : Table 1

Regarding the chemical formula A7, the methoxy group -[OCH ₃ ] may be an alterna tive for the hydroxyl group -[OH] on the aromatic moiety, that is not part of the anthraqui- none ring system. Preferably the dye is selected from the group comprising the coloring agents known under the trademark BEMACRON S/SE/E from CHT Germany GmbH, or from Dystar Pte Ltd. Preferably the dye is selected from the group comprising BEMACRON Yellow S- 6GF, BEMACRON Yellow S-4g, BEMACRON Yellow Brown S-2RF1, BEMACRON Or ange S-g, BEMACRON Scarlet S-gFl, BEMACRON Scarlet S-BWF1, BEMACRON Ru- bine S-2GFL, BEMACRON Violet S-3R1, BEMACRON Violet S-B1F, BEMACRON Blue S-Bgl, BEMACRON Blue S-BB, BEMACRON Turquoise S-gF, BEMACRON Navy S- 2gl, BEMACRON Navy S-31, BEMACRON Black S-31, BEMACRON Black S-T, BEMACRON Yellow SE-Rdl, BEMACRON Yellow SE-1F, BEMACRON Orange SE- Rdl, BEMACRON Red SE-4g, BEMACRON Pink SE-RE1, BEMACRON Red SE-3B, BEMACRON Red SE-Rdl, BEMACRON Blue SE-1F, BEMACRON Blue SE-Rdl, BEMACRON Navy SE-R1X, BEMACRON Black SE-R1X, BEMACRON Black SE- Rd2R, BEMACRON Yellow E-3gl, BEMACRON Red E-FBI, BEMACRON Blue E-FBI, and BEMACRON Black E-R.

More preferably the dye is selected from the group comprising BEMACRON Black E-R, BEMACRON Yellow S-6GF, BEMACRON Rubine S-2GFL, BEMACRON Blue RS, BEMACRON Blue E-FBL 150, BEMACRON Red E-FBL, BEMACRON Blue S- BGL, BEMACRON Yellow E-3gl, BEMACRON Lumin. Yellow SEL-8G, and BEMACRON Lumin. Red SEL-G. Furthermore, the dye may be selected from the group comprising polymethine dyes. Preferably, the polymethine dyes from the companies BLJFA GmbH & Co. KG, BLJFA Chemikalien GmbH & Co. KG, BLJFA Composite Systems GmbH & Co. KG, and/or BLJFA Reinigunssysteme GmbH & Co. KG may be used.

With regard to further advantages and technical features of the display device it is referred to the method for producing a display device, the examples and the further description.

The present invention further relates to the method for producing the above described display device, comprising the steps of a) providing a blank display device, wherein the blank display device comprises at least one functional layer, and at least one rear support layer, wherein the functional layer is next to the rear support layer, wherein an upper surface of the rear support layer is opposite to a lower surface of the rear support layer and contacts a lower surface of the functional layer, wherein the functional layer comprises at least two functional elements, that are light transmittance for visible light and are illuminable by at least one light source, wherein the rear support layer is light transmittance for visible light, b) producing at least one light barrier element into the rear support layer with a dye, such that the dye is molecularly solved in the material of the rear support layer and such that the light barrier element extends essentially vertically- i.e. with an angle of 90° +/- 50% - from the lower surface of the rear support layer into the rear support layer and is arranged between of at least two superposed functional elements of the superposed functional layer, and such that the light barrier element arranged in the rear support layer at least partly surrounds spaced apart at least one superposed functional element. The method basically comprises two steps, i.e. providing the blank display device and producing the light barrier element. The blank display device preferably is a display device that comprises all parts except for the light barrier element, the protrusion element and the light source. The blank display de vice may be produced by a standard production method.

With regard to the first processing step - providing the blank display device - the blank display device may be produced by film insert molding, in-mold decoration, in-mold label ling, lamination, over-molding, multi-material injection molding and/or a stacking process of the layers. Any other standard process known for producing the blank display device may be used.

The invention will further be described without limiting effect by reference to the at tached drawings, wherein the figures show:

Fig.1 a schematic view of a display device, according to prior art,

Fig.2 two schematics views from different perspectives of the display device ac cording to a preferred embodiment of the invention, and

Fig.3 a flowchart showing the steps of a method for producing the display device, according to a preferred embodiment of the invention.

Figure 1 shows a schematic view of a display device 1 known in prior art. The display device according to prior art has a layered structure with a front layer 2, a functional layer 3 having two functional elements 4, and a rear support layer 5. The functional elements 4 in the functional layer 3 are transparent for visible light and are illuminable by a light source 6. There are two light sources 6, one for each functional element 4. The display device 1 further has a protrusion element 7 between the two light sources 6. However, despite of the protru sion element 7 there is stray light contamination 8 of the neighboring functional element 4 by the light source 6.

Figure 2 shows two schematic views of a display device 10 according to a preferred embodiment. The display device 10 according to the preferred embodiment has a layered structure as is visible from figure 2a). The display device 10 has a front layer 12, a functional layer 14, and a rear support layer 16. Figure 2b) shows the display device 10 viewed onto the rear support layer 16. As can be seen in figure 2a) the functional layer 14 is sandwiched between the front layer 12 and the rear support layer 16. An upper surface 18 of the rear support layer 16 is opposite to a lower surface 20 of the rear support layer 16 and contacts a lower surface 22 of the functional layer 14. An upper surface 24 of the functional layer 14 contacts a lower surface 26 of the front layer 12. The functional layer 14 comprises at least two functional elements 28a, 28b. The functional layer is based on the functional layer ma terial. In this embodiment the functional layer material comprises the coloring agent piano black and red. The functional elements 28a, 28b in the functional layer 14 are transparent for visible light and are illuminable by a light source 30. The functional elements 28a, 28b are formed by the coloring agent red. There are two light sources 30a 30b, one for each functional element 28a, 28b. The functional elements 28a 28b have a night and day marking, meaning that the functional elements 28a 28b are not visible to the user as long as the func tional elements 28a 28b are not illuminated. However, the functional elements 28a 28b be come visible to the user when illuminated by the light sources 30a 30b. The light sources 30a 30b are installed behind the display device 10. The rear support layer 16 is transparent for visible light to facilitate the illumination of the functional elements 28. Furthermore, the rear support layer 16 of the display device 10 comprises at least one light barrier element 32. The rear support layer 16 and the light barrier element 32 are provided as one-piece compo nent. The light barrier element 32 is adapted for reducing or preventing light scattering through the light barrier element 32. The light barrier element 32 is arranged in the rear support layer 16, such that it extends essentially vertically from the lower surface 20 of the rear support layer 16 into the rear support layer 16. Furthermore, the light barrier element 32 is arranged between the two superposed functional elements 28a, 28b of the superposed functional layer 14, as can easily be seen from the perspective in figure 2a). In this preferred embodiment the light barrier element 32 extends such far into the rear support layer 16 that its vertical extent essentially corresponds to the thickness of the rear support layer 16. Fur thermore, the light barrier element 32 at least partly surrounds spaced apart at least one su perposed functional element 28a, 28b for effective prevention of stray light contamination. When the display device 10 is viewed from the perspective of figure 2b), the light barrier element 32 partially surrounds the functional elements 28a, 28b. From the perspective in Figure 2b) the light barrier element 32 has the form of a “H”.

In this preferred embodiment the two light sources 30a and 30b are OLED light source. The light emitted by the OLEDs is narrow-banded and corresponds to an absorption spec trum of the light barrier element 32.

In order to further reduce stray light contamination of neighboring functional elements 28a, 28b in this embodiment the display device 10 also comprise a protrusion element 34. The protrusion element 34 extends out of the lower surface 20 of the rear support layer 16 and is arranged between the two superposed functional elements 28a, 28b of the superposed functional layer 14. In this embodiment the protrusion element 34 is arranged on the lower surface 20 of the rear support layer 16 and positioned on the light barrier element 32. Fur thermore, the protrusion element 36 is in between the two light sources 30a, 30b. The display device 10 also comprises an anti-scratch layer 36 on an upper surface 38 of the front layer 12. The anti-scratch layer 36 is transparent for visible light to allow the visibility of the functional elements 28a, 28b for the user.

The front layer 12 of the display device 10 is also transparent. In this embodiment it comprises polycarbonate (PC). Furthermore, the rear support layer 16 comprises a mixture of polycarbonate (PC) and acrylonitrile butadiene styrene (ABS).

In the preferred embodiment in figure 2, the front layer 12 has a thickness 40 of 300 pm, the functional layer 14 has a thickness 42 of 250 pm, the rear support layer 16 has a thickness 44 of 2000 pm. Furthermore, a vertical extent 46 of the light barrier element 32 corresponds to the thickness 44 of the rear support layer. A thickness 48 of the light barrier element 32 varies between 200 pm and 800 pm.

Figure 3 shows a flow chart of the method for producing the above display device. In a first step, a blank display device is produced. The blank display device comprises all the parts of the display device 10 shown in figure 2 except for the light barrier element 32, the protrusion element 34 and the light source 30. The blank display device is similar to the display device 1 known from prior art and shown in figure 1, without the protrusion element 7 and the light source 6. The blank display device may be produced by film insert molding. In a second step of the method the light barrier element 32 is formed.

REFERENCE NUMERALS display device (prior art) 1 front layer (prior art) 2 functional layer (prior art) 3 functional element (prior art) 4 rear support layer (prior art) 5 light source (prior art) 6 protrusion element (prior art) 7 display device 10 front layer 12 functional layer 14 rear support layer 16 upper surface of rear support layer 18 lower surface of rear support layer 20 lower surface of functional layer 22 upper surface of functional layer 24 lower surface of front layer 26 functional element 28 light source 30 light barrier element 32 protrusion element 34 anti-scratch layer 36 upper surface of front layer 38 thickness of front layer 40 thickness of functional layer 42 thickness of rear support layer 44 vertical extent of light barrier element 46 thickness of light barrier element 48