FIELD OF THE INVENTION

The invention relates to a three-dimensional plastic product with retroreflective properties and LIDAR-detectability and to processes for producing said three-dimensional plastic product. The invention further relates to a modified three-dimensional product comprising one or more of said three-dimensional plastic products with retroreflective properties and one or more further parts or components attached thereto, to a Laser Imaging Detection And Ranging (LIDAR) process of said three-dimensional plastic product or of said modified three- dimensional product, to the use of the three-dimensional plastic product in the form of a pellet or filament for the production of a ready-to-use three-dimensional plastic product and to further uses of said three-dimensional plastic product or of said modified three-dimensional product.

BACKGROUND OF THE INVENTION

Retroreflective effects are used in a variety of applications. For example, to improve the visibility of road signs, road markers, textiles, cars, et cetera, under dark conditions, or simply to improve their visual appearance. Retroreflection occurs by the tandem action of refraction of the incident light through the upper surface of for example a spherical glass bead, internal reflection from the lower onside surface of the spherical glass bead and subsequent refraction of the light as it exits the upper surface of the spherical glass bead, travelling back to the direction from which the impinging light came.

The present invention concerns three-dimensional plastic products, such as for example vehicle parts. Being able to clearly identify objects, such as vehicles, during nighttime or in dimly-lit conditions is a challenge. Retroreflectivity could greatly improve the visibility and/or LIDAR-detectability of such objects. Vehicle parts, particularly automotive parts, typically have a very smooth surface with a glossy or semi-glossy appearance to make them appealing from an aesthetic point of view. Therefore, there is a need to provide three-dimensional plastic products having a smooth surface, particularly plastic vehicle parts, with retroreflective properties.

DE102016001026A1 discloses a raw material for 3D printing comprising a thermoplastic material and reflective or retroreflective glass beads. It is described in DE102016001026A1 that retroreflectivity is only observed if the retroreflective glass beads are located at the surface that receives light. If the retroreflective glass beads are covered with the thermoplastic material, the effect is extremely minimized or zero. It is described that retroreflective injection-molded plastic articles therefore are not common because the retroreflective glass beads are encased by the plastic. DE102016001026A1 further describes that a thermoplastic mixture comprising more than 50 wt.% of reflective glass beads resulted after 3D printing in a reflective object with reflective glass beads protruding from the surface of the object. The reflective glass beads protruding from the surface were not covered with thermoplastic material. Only filaments and 3D-printed objects wherein retroreflective glass beads protruded from the surface and wherein the glass beads protruding from the surface were not covered with thermoplastic material showed retroreflective properties. DE102016001026A1 only describes the use of retroreflective glass beads with a refractive index between 1.7 and 1.9, preferably hemispherically coated with a metallic coating.

W02005/033194A1 concerns retroreflective polymeric compounds and articles made thereof. The compounds and articles include a thermoplastic polymer, glass beads and metallic flakes. At least part of the glass beads are hemispherically coated with a metallic coating. Example 1 discloses a composition comprising 1.76 wt.% carbon black pigment, 16 wt.% of aluminium coated BaTiO microspheres (38 pm; Prizmalite Industries), 4 wt.% of uncoated BaTiO microspheres (8.5 pm; Prizmalite Industries), 77.36 wt.% ASA thermoplastic polymer and 0.88 wt.% of Sparkle Silver aluminium flakes of an unknown size (Silberline Mfg. Co.).

It is described in W02005/033194A1 that pure barium titanate is a clear crystalline ceramic having a refractive index of 2.40 and that BaTiO microbeads are dense clear spheres, consisting primarily of BaTiO , but also containing substantial concentrations of SiCh, B2O3 and CaO, as well as traces of other metal oxides. Hence, the BaTiO microbeads do not have a refractive index of 2.40. Prizmalite Industries only offers BaTiO microbeads with a refractive index of 1.9 that are hemispherically coated with an aluminium coating (product P2453BTA). It is described in the Guidelines for using Prizmalite® P2453BTA retro reflective spheres, distributed by Cospheric LLC, that “The aluminium coating on half the barium titanate spheres provides the mechanism for retroreflectivity. The light passes through the clear half of the sphere and “bounces ” off the aluminum coating. The combination of barium titanate ’s RI of 1.9 and the hemispheric coating of aluminum creates retroreflectivity and accounts for the more intense and direct light refraction achieved. ” It is further described in these guidelines that “these coatings have been designed to promote the migration of the microspheres to the surface of the inks or coatings in which they are incorporated. The concept of retroreflection depends on the passage of the light through the clear, uncoated hemisphere of the glass sphere. If the sphere is not physically situated for light to pass through it, no retro reflectivity can result. Prizmalite’ s coatings create a tension between the coating and its surrounding resin that forces the sphere to “pop up ” to the surface, thus maximizing its potential exposure to light. Coating the spheres enhances the retro reflective effect by achieving this placement and reduces the amount of spheres required because the coated spheres perform so much more efficiently than uncoated ones. ”

The present inventors have found that using spherical glass beads with a refractive index of 1.9 or lower does not provide three-dimensional plastic products with sufficient retroreflective properties in plastic products wherein the spherical glass beads do not protrude from the plastic or polymer matrix, not even when combined with pigment flakes.

As shown in the experimental section, it was found that using a hemispheric aluminium coating on the spherical glass beads with a refractive index of 1.9 in plastic products wherein the spherical glass beads do not protrude from the plastic or polymer matrix worsens the retroreflective properties.

It is an object of the invention to provide three-dimensional plastic products with improved retroreflective properties and/or improved LIDAR-detectability.

It is a further object of the invention to provide three-dimensional plastic products with improved retroreflective properties and/or improved LIDAR-detectability, wherein the three- dimensional plastic products comprise retroreflective spherical glass beads that do not protrude from the plastic matrix.

It is another object of the invention to provide three-dimensional plastic products with smooth, glossy or semi-glossy retroreflective surfaces and/or smooth, glossy or semi-glossy LIDAR-detectable surfaces.

SUMMARY OF THE INVENTION

The inventors have unexpectedly established that the objectives can be met by employing spherical glass beads with a higher refractive index combined with pigment flakes at a certain weight fraction in the continuous plastic matrix. The inventors have further found that applying a hemispheric light-reflective coating onto the spherical glass beads has an adverse effect on retroreflection/LIDAR-detectability in three-dimensional plastic products wherein the spherical glass beads do not protrude from the plastic matrix. Accordingly, in a first aspect the invention provides a three-dimensional plastic product (1) with an outer surface (A), wherein at least part (B) of the outer surface (A) has retroreflective properties, wherein said three-dimensional plastic product (1) consists, based on the total weight of the three-dimensional plastic product (1), of:

• 25 - 95.9 wt.% of a polymer chosen from thermoplastic and thermoset polymers;

• 4 - 70 wt.% of spherical glass beads, wherein said spherical glass beads have a median particle diameter D50, as measured with laser diffraction, between 1 and 150 pm, and a refractive index, measured at a wavelength Z of 589 nm, between 2.0 and 2.8, wherein the spherical glass beads are not hemispherically coated with a light-reflective coating;

• 0.1 - 15 wt.% of pigment flakes chosen from the group consisting of metallic pigment flakes, pearlescent pigment flakes or a combination thereof, said pigment flakes having a median diameter, as measured with laser diffraction, between 1 and 75 pm; and

• 0 - 15 wt.% of one or more further ingredients, wherein the minimum size of the three-dimensional plastic product (1) in all directions is at least 500 pm, and wherein part (B) of the outer surface (A) with retroreflective properties comprises one or more outer retroreflective surface parts (C) wherein the spherical glass beads do not protrude from the polymer matrix.

In a second aspect, a modified three-dimensional product (2) is provided comprising:

• one or more three-dimensional plastic products (1) according to the first aspect and one or more further parts or components (3) attached thereto; or

• one or more further parts or components (3) and one or more three-dimensional plastic products (1) according to the first aspect attached thereto, with the proviso that at least part of the one or more outer retroreflective surface parts (C) of the three-dimensional plastic products (1) according to the first aspect is not covered by the one or more further parts or components (3).

In a third aspect, the invention provides a process for producing the three-dimensional plastic product (1) with retroreflective properties according to the first aspect, wherein the polymer is a thermoplastic polymer, said process comprising the steps of:

(a) providing the thermoplastic polymer, the spherical glass beads, the pigments flakes and the optional further ingredients; (b) compounding the ingredients provided in step (a) at a temperature above the melting point of the thermoplastic polymer;

(c) providing the mixture obtained in step (b) into a mould or extruding the mixture obtained in step (b); and

(d) cooling the mixture in the mould to a temperature below the melting point of the thermoplastic polymer and removing the three-dimensional plastic product (1) with retroreflective properties from the mould or cooling the extrudate to a temperature below the melting point of the thermoplastic polymer to provide the three-dimensional plastic product (1) with retroreflective properties.

In a fourth aspect, the invention provides a process for producing the three-dimensional plastic product (1) with retroreflective properties according to the first aspect, wherein the polymer is a thermoset polymer, said process comprising the steps of:

(a) providing a thermoset curable resin, the spherical glass beads, the pigments flakes and the optional further ingredients;

(b) mixing the ingredients provided in step (a);

(c) providing the mixture obtained in step (b) into a mould;

(d) curing the mixture in the mould to provide the three-dimensional plastic product (1) with retroreflective properties; and

(e) removing the three-dimensional plastic product (1) with retroreflective properties from the mould.

In a fifth aspect, the invention provides a Laser Imaging Detection And Ranging (LIDAR) process of the three-dimensional plastic product (1) according to the first aspect or of the modified three-dimensional product (2) according to the second aspect, said process comprising the steps of:

(i) providing a LIDAR device comprising a source of electromagnetic radiation, a receiver and optionally a Global Positioning System (GPS);

(ii) transmitting electromagnetic radiation from the source of electromagnetic radiation of the LIDAR device to the three-dimensional plastic product (1) or to the modified three- dimensional product (2); (iii) scanning the electromagnetic radiation reflected by the three-dimensional plastic product

(1) or by the modified three-dimensional product (2) with the receiver of the LIDAR device; and

(iv) computing from the differences between the transmitted electromagnetic radiation and the scanned reflected electromagnetic radiation, preferably as a function of time, one or more of:

• the distance between the three-dimensional plastic product (1) or the modified three-dimensional product (2) and the LIDAR device;

• the acceleration of the three-dimensional plastic product (1) or of the modified three-dimensional product (2);

• the deceleration of the three-dimensional plastic product (1) or of the modified three-dimensional product (2);

• the direction of movement of the three-dimensional plastic product (1) or of the modified three-dimensional product (2);

• the speed of the three-dimensional plastic product (1) or of the modified three- dimensional product (2), preferably the speed relative to that of the LIDAR device; and

• a 3D image of the three-dimensional plastic product (1) or of the modified three- dimensional product (2).

In a sixth aspect, the invention provides the use of the three-dimensional plastic product (1) according to the first aspect in the form of a filament or pellet, wherein the polymer is a thermoplastic polymer, in the production of a ready-to-use three-dimensional plastic product (1) according to the first aspect, wherein the polymer is a thermoplastic polymer.

In a seventh aspect, the invention provides the use of the three-dimensional plastic product (1) according to the first aspect (1) or of the modified three-dimensional product (2) according to the second aspect,

• in Laser Imaging Detection And Ranging (LIDAR) of said three-dimensional plastic product (1) or of the modified three-dimensional product (2); and/or

• to improve the visibility of said three-dimensional plastic product (1) or of said modified three-dimensional product (2) under visible light conditions; and/or to prepare a three-dimensional image of said three-dimensional plastic product (1) or of said modified three-dimensional product (2).

DEFINITIONS

The wording "the spherical glass do not protrude from the polymer matrix'’ as used herein means that the spherical glass beads are covered by the polymer matrix. The outer retroreflective surface part(s) (C) of the three-dimensional plastic product (1) as defined herein can have a smooth surface, glossy appearance or semi-glossy appearance wherein the spherical glass beads are fully embedded in the polymer matrix but can also have a rough(er) surface or matte appearance when the spherical glass beads protrude from the surface but are still covered by the polymer matrix. The terms "plastic’ and "polymer matrix’ are used interchangeably.

The term "pigment’ as used herein refers to particulate colorants, such as spherical parts or flakes. They are insoluble in the binder or solvent used.

The term "dye’ as used herein refers to colorants that can be molecularly dissolved in the binder or solvent used.

The term "colorant’ as used herein includes pigments as well as dyes.

The term "titanium suboxides’ as used herein refers to titanium oxide compound with the formula Ti„C)2»-/, wherein n is an integer greater than 1.

The term "LIDAR’ is an acronym of "light detection and ranging’ or "laser imaging, detection, and ranging’ and concerns a method for determining ranges (variable distance) to an object, speed of an object and 3D-representations of an object by targeting the object with electromagnetic radiation, typically laser light, and measuring the time for the reflected electromagnetic radiation to return to a receiver.

The term "vehicle’ as used herein refers to a physical object used suitable for transporting people or goods. Non-limiting examples of vehicles in the context of this invention are chosen from the group consisting of cars, lorries, trucks, bikes, mopeds, scooters, motorcycles, trains, trams, boats, ships, drones, skateboards, missiles, helicopters and aircrafts. In a preferred embodiment, the vehicle is chosen from cars, lorries, trucks, bikes, mopeds, scooters and motorcycles. BRIEF DESCRIPTION OF THE FIGURES

Figures 1, 2a and 2b together depict what is meant by "an interrupted or uninterrupted outer retroreflective surface part (C)

Figure 1 depicts a three-dimensional plastic product (1) with an outer surface (A), wherein part (B) of the outer surface (A) has retroreflective properties and wherein part (B) comprises two 'uninterrupted' outer retroreflective surface parts (C).

Figure 2a depicts a three-dimensional plastic product (1) with an outer surface (A), wherein part (B) of the outer surface (A) has retroreflective properties and wherein part (B) comprises two 'interrupted' outer retroreflective surface parts (C). Both outer retroreflective surface parts (C) are interrupted by parts of outer surface (B).

Figure 2b depicts a three-dimensional plastic product (1) with an outer surface (A), wherein part (B) of the outer surface (A) has retroreflective properties and wherein part (B) comprises two outer retroreflective surface parts (C) of which one outer retroreflective surface part (C) is 'interrupted' by parts of outer surface (B) and one outer retroreflective surface part (C) is ‘ uninterrupted'’ .

Figure 3 depicts a modified three-dimensional product (2) comprising a three- dimensional plastic product (1) according to the invention and a further component (3) attached thereto. The three-dimensional plastic product (1) has an outer surface (A), of which part (B) has retroreflective properties and wherein part (B) comprises one outer retroreflective surface part (C) - that coincides with part (B) - wherein the spherical glass beads do not protrude from the polymer matrix. The outer retroreflective surface part (C) is not covered by the further component (3) attached to the three-dimensional plastic product (1).

Figure 4 depicts a modified three-dimensional product (2) comprising a three- dimensional plastic product (1) according to the invention and a further component (3) attached thereto. The three-dimensional plastic product (1) has an outer surface (A), of which part (B) has retroreflective properties and wherein part (B) comprises two outer retroreflective surface parts (C) wherein the spherical glass beads do not protrude from the polymer matrix. The two outer retroreflective surface parts (C) are not covered by the further component (3) attached to the three-dimensional plastic product (1).

Figure 5 depicts a cross-section (in a direction perpendicular to outer retroreflective surface part (C)) of a three-dimensional plastic product (1) with a smooth, glossy or semi-glossy outer retroreflective surface part (C) wherein the spherical glass beads (4) are fully embedded in the polymer matrix (5). Outer retroreflective surface part (C) coincides with outer surface part (B).

Figure 6 depicts a cross-section of a three-dimensional plastic product (1) with a matte appearance of the outer retroreflective surface part (C) wherein the spherical glass beads (4) protrude from the surface to create a certain roughness but are still covered by the polymer matrix (5). Outer retroreflective surface part (C) coincides with outer surface part (B).

Figure 7 depicts retroreflection of surfaces of three-dimensional plastic products under an angle of 45°.

DETAILED DESCRIPTION

Three-dimensional plastic product

A first aspect of the invention concerns a three-dimensional plastic product (1) with an outer surface (A), wherein at least part (B) of the outer surface (A) has retroreflective properties, wherein said three-dimensional plastic product (1) consists, based on the total weight of the three-dimensional plastic product (1), of:

• 25 - 95.9 wt.% of a polymer chosen from thermoplastic and thermoset polymers;

• 4 - 70 wt.% of spherical glass beads, wherein said spherical glass beads have a median particle diameter D50, as measured with laser diffraction, between 1 and 150 pm, and a refractive index, measured at a wavelength Z of 589 nm, between 2.0 and 2.8, wherein the spherical glass beads are not coated with a light-reflective coating;

• 0.1 - 15 wt.% of pigment flakes chosen from the group consisting of metallic pigment flakes, pearlescent pigment flakes or a combination thereof, said pigment flakes having a median diameter, as measured with laser diffraction, between 1 and 75 pm; and

• 0 - 15 wt.% of one or more further ingredients, wherein the minimum size of the three-dimensional plastic product (1) in all directions is at least 500 pm, and wherein part (B) of the outer surface (A) with retroreflective properties comprises one or more outer retroreflective surface parts (C) wherein the spherical glass beads do not protrude from the polymer matrix.

As will be appreciated by those skilled in the art, the wording "the three-dimensional plastic product (1) consists of means that the combined amounts of polymer (thermoplastic or thermoset), spherical glass beads, pigment flakes and further ingredients add up to 100 wt.% of the three-dimensional plastic product (1).

The wording "outer surface with retroreflective properties’ as used herein refers to a surface that, solely based on its composition, is able to reflect light back into the direction from which the impinging light came, irrespective of whether light can actually reach this outer surface.

In a preferred embodiment, the one or more outer retroreflective surface parts (C) of the three-dimensional plastic product (1) as defined herein are smooth or have a glossy or semiglossy appearance, wherein the spherical glass beads are fully embedded in the polymer matrix. Such a three-dimensional plastic product (1) can be produced in a smooth mould. Such an embodiment is depicted in Figure 5. In another embodiment, the one or more outer retroreflective surface parts (C) of the three-dimensional plastic product (1) as defined herein are rough or have a matte appearance, wherein the spherical glass beads protrude from the surface but are still covered by the polymer matrix. Such a three-dimensional plastic product (1) can be produced in a mould with surface roughness. Such an embodiment is depicted in Figure 6.

In a preferred embodiment, the surface area of the one or more outer retroreflective surface parts (C) of the three-dimensional plastic product (1) as defined herein are uninterrupted, meaning that they do not enclose outer retroreflective surface parts (B). Such a preferred embodiment is depicted in Figure 1. In an embodiment, the surface area of the one or more outer retroreflective surface parts (C) of the three-dimensional plastic product (1) as defined herein are interrupted, meaning that they enclose outer retroreflective surface parts (B) and/or outer surface parts (A). Such an embodiment is depicted in Figure 2a.

As explained hereinbefore, part (B) of outer surface (A) has retroreflective properties. Unlike the one or more outer retroreflective surface parts (C), the remainder of outer retroreflective surface part (B) may have spherical glass beads that protrude from the surface without being covered by the polymer matrix. Unlike Prizmalite’s hemispherically aluminum (HAC) coated barium titanate spherical glass beads having a refractive index of 1.9, the spherical glass beads having a refractive index between 2.0 and 2.8, measured at a wavelength Z of 589 nm, that are not hemispherically coated with a metallic coating do not migrate to the surface of the plastic product during production. Hence, in a preferred embodiment, the spherical glass beads are homogeneously distributed across the three-dimensional plastic product (1). In another preferred embodiment, the spherical glass beads and the pigment flakes are homogeneously distributed across the three-dimensional plastic product (1).

Since the density of typical thermoplastic and thermoset polymers is much lower than the density of spherical glass beads having a refractive index, measured at a wavelength Z of 589 nm, of between 2.0 and 2.8, the volume fraction of the spherical glass beads in the three- dimensional plastic product (1) is typically lower than that of the polymer phase, meaning that the spherical glass beads are typically fully encased in a continuous matrix of the polymer phase.

In a preferred embodiment, the surface area of the at least part (B) of outer surface (A) having retroreflective properties constitutes at least 1 % of the surface area of outer surface (A), more preferably at least 5 %, even more preferably at least 10 %, such as at least 20 %, at least 30 %, at least 40 %, at least 50 %, at least 60 %, at least 70 %, at least 80 %, at least 90 % or at least 99 %.

In a very preferred embodiment, the surface area of the at least part (B) of outer surface (A) having retroreflective properties constitutes 100% of the surface area of outer surface (A).

In another preferred embodiment, the surface area of the at least part (B) of outer surface (A) having retroreflective properties constitutes between 1 and 100 % of the surface area of outer surface (A), more preferably between 5 and 100 %, even more preferably between 10 and 100 %, such as between 20 and 100 %, between 30 and 100 %, between 40 and 100 %, between 50 and 100 %, between 60 and 100 %, between 70 and 100 %, between 80 and 100 %, between 90 and 100 % or between 95 and 100 %.

In another embodiment, the surface area of the at least part (B) of outer surface (A) having retroreflective properties constitutes between 1 and 95 % of the surface area of outer surface (A), such as between 5 and 90 %, between 10 and 85 %, between 15 and 80 % or between 20 and 75 %. In a preferred embodiment, the surface area of the one or more outer retroreflective surface parts (C) constitutes at least 1 % of the surface area of part (B) of outer surface (A), more preferably at least 5 %, even more preferably at least 10 %, such as at least 20 %, at least 30 %, at least 40 %, at least 50 %, at least 60 %, at least 70 %, at least 80 %, at least 90 % or at least 99 %.

In a very preferred embodiment, the surface area of the one or more outer retroreflective surface parts (C) constitutes 100% of the surface area of part (B) of outer surface (A). Such a very preferred embodiment is depicted in Figure 3.

In another preferred embodiment, the surface area of the one or more outer retroreflective surface parts (C) constitutes between 1 and 100 % of the surface area of part (B) of outer surface (A), more preferably between 5 and 100 %, even more preferably between 10 and 100 %, such as between 20 and 100 %, between 30 and 100 %, between 40 and 100 %, between 50 and 100 %, between 60 and 100 %, between 70 and 100 %, between 80 and 100 %, between 90 and 100 % or between 95 and 100 %.

In another embodiment, the surface area of the one or more outer retroreflective surface parts (C) constitutes between 1 and 95 % of the surface area of part (B) of outer surface (A), such as between 5 and 90 %, between 10 and 85 %, between 15 and 80 % or between 20 and 75 %.

As will be appreciated by those skilled in the art, if the surface area of the one or more outer retroreflective surface parts (C) constitutes 100 % of the surface area of part (B) of outer surface (A), then the complete surface area of part (B) of outer surface (A) is constituted by the one or more outer retroreflective surface parts (C), meaning that the outer retroreflective surface part (B) and the one or more outer retroreflective surface parts (C) coincide.

In a preferred embodiment, the surface area of the one or more outer retroreflective surface parts (C) constitutes at least 1 % of the surface area of outer surface (A), more preferably at least 5 %, even more preferably at least 10 %, such as at least 20 %, at least 30 %, at least 40 %, at least 50 %, at least 60 %, at least 70 %, at least 80 %, at least 90 % or at least 99 %.

In a very preferred embodiment, the surface area of the one or more outer retroreflective surface parts (C) constitutes 100 % of the surface area of outer surface (A). As will be appreciated by those skilled in the art, if the surface area of the one or more outer retroreflective surface parts (C) constitutes 100% of the surface area of outer surface (A), then the complete surface (A) is a single uninterrupted retroreflective outer surface, wherein the spherical glass beads do not protrude from the polymer matrix. In this particular case, outer surface (A) coincides with outer retroreflective surface (B) which in turn coincides with the (one or more) outer retroreflective surface part(s) (C).

In another preferred embodiment, the surface area of the one or more outer retroreflective surface parts (C) constitutes between 1 and 100 % of the surface area of outer surface (A), more preferably between 5 and 100 %, even more preferably between 10 and 100 %, such as between 20 and 100 %, between 30 and 100 %, between 40 and 100 %, between 50 and 100 %, between 60 and 100 %, between 70 and 100 %, between 80 and 100 %, between 90 and 100 % or between 95 and 100 %.

In another embodiment, the surface area of the one or more outer retroreflective surface parts (C) constitutes between 1 and 95 % of the surface area of outer surface (A), such as between 5 and 90 %, between 10 and 85 %, between 15 and 80 % or between 20 and 75 %.

The three-dimensional plastic product (1) consists of the composition as defined hereinbefore. Hence, the fact that the three-dimensional plastic product (1) has an outer surface (A) wherein at least part (B) of the outer surface (A) has retroreflective properties is a direct result of this specific composition and not of a part or component (3), such as a retroreflective coating, that may have been applied on part of the three-dimensional plastic product (1) to provide a ‘modified three-dimensional product (2f .

No matter how complex the three-dimensional geometry of the plastic product (1) is, the at least part (B) of the outer surface (A) shows retroreflectivity, provided that light can reach the outer retroreflective surface.

The three-dimensional plastic product (1) has a minimum size in all directions of at least 500 pm. The term ‘minimum size in all directions'’ as used herein means that the length, the width and the height of the three-dimensional plastic product (1) are at least 500 pm. Hence, the three-dimensional plastic product (1) can be distinguished from for example coating layers typically having a thickness of far less then 500 pm. In a preferred embodiment, the three-dimensional plastic product (1) has a minimum size in all directions of at least 1 mm, at least 2 mm, at least 3 mm, at least 4 mm, at least 5 mm, at least 6 mm, at least 8 mm or at least 10 mm.

In another preferred embodiment, the three-dimensional plastic product (1) has a size in all directions of between 500 pm and 10 m, between 2 mm and 10 m, between 3 mm and 10 m, between 4 mm and 10 m, between 5 mm and 10 m, between 6 mm and 10 m, between 8 mm and 10 m or between 10 mm and 10 m.

In yet another preferred embodiment, the three-dimensional plastic product (1) has a size in all directions of between 500 pm and 9 m, between 500 pm and 7 m, between 500 pm and 5 m, between 500 pm and 3 m, between 500 pm and 2 m, between 500 pm and 1 m, between 500 pm and 80 cm or between 500 pm and 60 cm.

In yet another preferred embodiment, the three-dimensional plastic product (1) has a size in all directions of between 1 mm and 5 m, between 2 mm and 3 m, between 3 mm and 2 m, between 5 mm and 1.8 m, between 1 cm and 1.5 m or between 2 cm and 1 m.

In an embodiment, the three-dimensional plastic product (1), wherein the polymer is a thermoplastic polymer, has the form of a filament or pellet. Filaments or pellets can be used in the production of a ready-to-use three-dimensional plastic product (1) in accordance with the first aspect, for example using extrusion and injection moulding.

In another embodiment, wherein the polymer is a thermoplastic or thermoset polymer, the three-dimensional plastic product (1) is a ready-to-use product, preferably a vehicle part, more preferably an automotive body part, such as an automotive body part chosen from the group consisting of bumpers, mirror housings, handles and radio antennae.

Polymer

The three-dimensional plastic product (1) comprises 25 - 95.9 wt.%, based on the weight of the plastic product (1), of a polymer chosen from thermoplastic and thermoset polymers. The terms "thermoplastic polymer’ and "thermoset polymer" as used herein have the common meaning in the art.

In an embodiment, the three-dimensional plastic product (1) comprises 25 - 94 wt.%, based on the weight of the plastic product (1), of the polymer, such as 25 - 92 wt.%, 25 - 90 wt.%, 25 - 85 wt.%, 25 - 80 wt.%, 25 - 75 wt.%, 25 - 70 wt.%, 25 - 65 wt.%, 25 - 60 wt.%, 25 - 55 wt.% or 25 - 50 wt.%.

In another embodiment, the three-dimensional plastic product (1) comprises 27 - 95.9 wt.%, based on the weight of the plastic product (1), of the polymer, such as 30 - 95.9 wt.%, 35 - 95.9 wt.%, 40 - 95.9 wt.%, 45 - 95.9 wt.%, 50 - 95.9 wt.% or 55 - 95.9 wt.%.

In an embodiment the polymer is a thermoset polymer, preferably a thermoset polymer chosen from the group consisting of phenol formaldehyde (PF), urea formaldehyde (UF), melamine formaldehyde (MF), epoxies (EP), polyurethanes (PU) and unsaturated polyester (UP).

In a preferred embodiment, the polymer is a thermoplastic polymer, more preferably a thermoplastic polymer chosen from the group consisting of homopolymers and copolymers of polyethylene (PE, LDPE, HDPE, LLDPE), polypropylene (PP), polyvinylchloride (PVC), polystyrene (PS), polymethylmethacrylate (PMMA), polyamide (PA), polyoxymethylene (POM), polycarbonate (PC), polyethylene terephthalate (PET), polyethylene terephthalate glycol (PETG), polysulfone (PSU), polyimide (PI), polybutene (PB), polyether ether ketone (PEEK), poly(acrylonitrile butadiene styrene) (ABS), poly(acrylonitrile butadiene acrylate) (ABA), poly(acrylic styrene acrylonitrile) (ASA), poly(lactic acid) (PLA), nylon and blends thereof.

In an even more preferred embodiment, the polymer is a thermoplastic polymer chosen from the group consisting of polyethylene (PE, LDPE, HDPE, LLDPE), polypropylene (PP), polystyrene (PS) and polyethylene terephthalate glycol (PETG).

Spherical glass beads

As defined hereinbefore, the three-dimensional plastic product (1) comprises spherical glass beads, wherein said spherical glass beads have a median particle diameter D50, as measured with laser diffraction, between 1 and 150 pm, and a refractive index, measured at a wavelength X of 589 nm, between 2.0 and 2.8, wherein the spherical glass beads are not hemispherically coated with a light-reflective coating.

In preferred embodiments, the term "glass’’ in "spherical glass beads’ as used herein refers to non-crystalline, amorphous solid and transparent material made of oxides. In other embodiments, the term "glass' in "spherical glass beads' refers to solid and transparent material made of oxides and containing some microcrystallinity. The refractive index of the spherical glass beads is closely related to the density of the glass, although the relationship is not linear. Because of the nature of glass, the density is approximately an additive function of its composition. Densities of spherical glass beads having refractive indices between 1.5 and 2.8 typically vary between 2.5 and 4.5 g/cm ³ .

In a preferred embodiment, the spherical glass beads have a refractive index, measured at a wavelength Z of 589 nm, of between 2.0 and 2.6, preferably between 2.1 and 2.4.

In another embodiment, the spherical glass beads as defined herein comprise at least two types of spherical glass beads.

Oxides that can be used in glass are oxides of silicon, boron, aluminium, sodium, barium, vanadium, titanium, lanthanum, strontium, zirconium, potassium, magnesium, iron, calcium, zinc, lithium, barium and lead. The spherical glass beads can for example comprise different combinations of silica (SiO2), boric oxide (B2O3), phosphorous pentoxide (P2O5), vanadium pentoxide (V2O5), arsenic trioxide (AS2O3), germanium oxide (GeO2), calcium oxide (CaO), sodium oxide (NaiO), magnesium oxide (MgO), zinc oxide (ZnO), aluminium oxide (AI2O3), potassium oxide (K2O), iron oxide (Fe2C>3), lead oxide (PbO), barium oxide (BaO), barium titanate (BaTiCh), titanium oxide (TiC ), lithium oxide (Li2O), strontium oxide (SrO), lanthanum oxide (La2O3), and zirconium oxide (ZrCh). Silica and boric oxide are generally the lowest in density. Glasses containing large weight percentages of these oxide therefore generally result in glass beads with low refractive indices. The refractive indices can be increased by adding oxides with higher molecular weights. Preferably, the spherical glass beads do not comprise PbO.

Glass beads having refractive indices in the range of 1.5 - 2.51 and their composition in terms of oxides are disclosed in WO2014/109564A1, which is incorporated herein by reference in its entirety. PbO-free transparent glass beads with refractive indices of above 2.15 are disclosed in US4,082,427, which is incorporated herein by reference in its entirety.

The spherical glass beads may be coloured spherical glass beads as long as they remain transparent. Both coloured spherical glass beads made from coloured transparent glass and spherical glass beads provided with a concentric transparent coloured coating are encompassed by the invention. The colour may be the natural colour caused by the composition of the oxides or may be deliberately chosen by adding ingredients having a specific colour. Coloured glass beads having high refractive indices and high transparency are disclosed in WO2014/109564A1.

The spherical glass beads have a median particle diameter D50, as measured with laser diffraction. Accordingly, the median particle diameter D50 is a volume median, based on a volume distribution. The median particle diameter D50 is the diameter where half of the population of spherical glass beads lies below. This volume median particle diameter is often referred to in the art as Dv50 or D _v o.5.

In a preferred embodiment, the spherical glass beads have a median particle diameter D50, as measured with laser diffraction, between 1.5 and 120 pm, more preferably between 2 and 100 pm, even more preferably between 3 and 80 pm, still more preferably between 4 and 50 pm, such as between 5 and 40 pm or between 6 and 30 pm.

In another embodiment, the spherical glass beads have a median particle diameter D50, as measured with laser diffraction, between 10 and 150 pm, such as between 15 and 150 pm, between 20 and 150 pm, between 25 and 150 pm, between 30 and 150 pm or between 35 and 150 pm.

In a very preferred embodiment, the spherical glass beads have a median particle diameter D50, as measured with laser diffraction, between 1 and 100 pm, such as between 1 and 75 pm, between 1 and 50 pm, between 1 and 45 pm, between 1 and 40 pm, between 1 and 35 pm, between 1 and 30 pm, between 1 and 25 pm, between 1 and 20 pm or between 1 and 15 pm.

The diameters D10 and D90 are often referred to in the art as DvlO or D _v o.i and Dv90 or DVO.9, respectively. The D10 diameter is the diameter where 10% of the population of spherical glass beads lies below. Similarly, the D90 diameter is the diameter where 90% of the population of spherical glass beads lies below.

The span, as measured by laser diffraction, of the particle size distribution of the spherical glass beads is defined by: 90 — 10 span = 50 In another embodiment, the spherical glass beads have a median particle diameter D50, as measured with laser diffraction, between 1 and 100 pm and a span between 0 and 1.9, preferably between 0 and 1.5, more preferably between 0 and 1, even more preferably between 0 and 0.5, such as between 0 and 0.2 or between 0 and 0.1.

In a preferred embodiment, the spherical glass beads have a median particle diameter D50, as measured with laser diffraction, between 1 and 50 pm and a span between 0 and 1.9, preferably between 0 and 1.5, more preferably between 0 and 1, even more preferably between 0 and 0.5, such as between 0 and 0.2 or between 0 and 0.1.

In another preferred embodiment, the spherical glass beads have a median particle diameter D50, as measured with laser diffraction, between 1 and 30 pm and a span between 0 and 1.9, preferably between 0 and 1.5, more preferably between 0 and 1, even more preferably between 0 and 0.5, such as between 0 and 0.2 or between 0 and 0.1.

In yet another preferred embodiment, the spherical glass beads have a median particle diameter D50, as measured with laser diffraction, between 1 and 20 pm and a span between 0 and 1.9, preferably between 0 and 1.5, more preferably between 0 and 1, even more preferably between 0 and 0.5, such as between 0 and 0.2 or between 0 and 0.1.

In still another preferred embodiment, the spherical glass beads have a median particle diameter D50, as measured with laser diffraction, between 1 and 15 pm and a span between 0 and 1.9, preferably between 0 and 1.5, more preferably between 0 and 1, even more preferably between 0 and 0.5, such as between 0 and 0.2 or between 0 and 0.1.

As will be appreciated by those skilled in the art, span = 0 corresponds to monodisperse spherical glass beads.

The spherical glass beads are not hemispherically coated with a light-reflective coating. Examples of a hemispherical light-reflective coating are hemispherical metal coatings, such as a hemispherical aluminium coating (HAC). The inventors have found that a hemispherical light-reflective coating has an adverse effect on retroreflectivity/LIDAR-detectability of the one or more outer surface parts (C) if the spherical glass beads do not protrude from the plastic or polymer matrix. In a preferred embodiment, the spherical glass beads are not coated with a material which is repellent to the polymer. Spherical glass beads coated with a material repellent to the polymer result in flotation of the spherical glass beads, i.e. migration of the spherical glass beads to the outer surface. Hence, the wording "coated with a material repellent to the polymer’ as used herein is considered interchangeable with "coated with a material that result in flotation of the spherical glass beads’ or "coated with a material that result in migration of the spherical glass beads to the outer surface’ . Such coatings are known in the art. As will be appreciated by those skilled in the art, whether the coating is repellent to the polymer depends on the type of polymer. It is within the skills of the artisan to exclude, based on flotation, certain coatings for a given polymer.

Examples of materials repellent to the polymer that are preferably excluded as coating on the spherical glass beads are:

• non-functional silanes, particularly (Ce-Cio)alkyl or aryl di- or tri-alkoxysilanes, such as hexyltrimethoxysilane, isooctyltrimethoxysilane and phenyltrimethoxysilane;

• non-functional silicones, particularly a mixture of a methylhydrogensilicone for flotation and a silanol-containing compound to attach the silicone to the spherical glass beads, such as a mixture of a methylhydrogensilicone and sodium or potassium methyl siliconate or a mixture of a methylhydrogensilicone and a low molecular weight silanol-containing polymer;

• non-functional fluorochemical materials, such as a non-functional fluorochemical polymers.

In this context, the wording "non-functional’ means "not containing functional reactive groups’ .

In an embodiment, the spherical glass beads are coated with a material that improves adhesion with the polymer. Such coatings are known in the art. As will be appreciated by those skilled in the art, whether the coating improves adhesion with the polymer depends on the type of polymer. It is within the skills of the artisan to choose, based on thermo-mechanical characterization, preferred coatings for a given polymer. In this regard, reference is made to Gelest’s brochure "Silane Coupling Agents - Connecting Across Boundaries’ , 3 ^rd edition., B. Arkles et al. , 2014, Gelest, Inc., Morrisville, PA, which is herein incorporated by reference in its entirety. Further reference is made to Swarco’s brochure "The game-changing industry system SWARCOFORCE’ , SWARCO Advanced Industry Systems, Austria, May 2020, incorporated herein by reference in its entirety, disclosing adhesion-promoting silane coatings for many different thermoplastic and thermoset polymers.

Typical examples of materials that generally improve adhesion with polymers are:

• functional silanes, such as silanes having mercapto-, glycidoxy- or amino- functional groups;

• zirconates, titananates, zircoaluminates, alkyl phosphate esters;

• functional zirconate molecules, such as zirconate molecules having mercapto-, glycidoxy- or amino-functional groups;

• functional organosilanes, such as 3-aminopropyltriethoxysilane, 3- methacryloxypropyltrimethoxysilane, gamma-glycidoxypropyltrimethoxysilane, gamma-aminopropyltriethoxysilane and gamma-aminopropyltrimethoxysilane;

• functional titanate molecules, such as titanate molecules having mercapto-, glycidoxy- or amino-functional groups.

In an embodiment, the spherical glass beads are not coated.

In a preferred embodiment, the amount of the spherical glass beads is 5 - 69 wt.%, more preferably 6 - 68 wt.%, even more preferably 7 - 65 wt.%, such as 8 - 60 wt.%, 9 - 55 wt.% or 10 - 50 wt.%, based on the weight of the three-dimensional plastic product (1).

In an embodiment, the amount of the spherical glass beads is 8 - 68 wt.%, more preferably 12 - 65 wt.%, even more preferably 18 - 60 wt.%, such as 20 - 55 wt.% or 30 - 50 wt.%, based on the weight of the three-dimensional plastic product (1).

In embodiments, the amount of the spherical glass beads is 4 - 68 wt.%, 4 - 66 wt.%, 4 - 64 wt.%, 4 - 62 wt.%, 4 - 60 wt.%, 4 - 58 wt.%, 4 - 56 wt.%, 4 - 54 wt.%, 4 - 52 or 4 - 50 wt.%, based on the weight of the three-dimensional plastic product (1).

In another embodiment, the amount of the spherical glass beads is 5 - 70 wt.%, 6 - 70 wt.%, 8 - 70 wt.%, 10 - 70 wt.%, 12 - 70 wt.% or 14 - 70 wt.%, based on the weight of the three-dimensional plastic product (1).

Pigment flakes

The three-dimensional plastic product comprises between 0.1 and 15 wt.% of pigment flakes chosen from the group consisting of metallic pigment flakes, pearlescent pigment flakes or a combination thereof, based on the weight of the three-dimensional plastic product, said pigment flakes having a median diameter, as measured with laser diffraction, between 1 and 75 pm.

Metallic pigment flakes and pearlescent pigment flakes constitute the two main types of (flake-like) special effect pigments. Metallic pigment flakes, also called metal effect pigment flakes, consist of flake-shaped metallic particles, used to give products metallic effect, colour or functional properties like anti-corrosion, heat resistance and conductivity. The small metal platelets behave like mirrors and can reflect incident light. Pearlescent pigment flakes simulate the luster of natural pearls and give the materials additional colour effects, such as angular colour dependence. Pearlescent pigments typically have several layers of materials with different refractive indices. Thin flakes of materials with low refractive indices, such as mica, silica, alumina or glass, are typically used as substrates and they are coated with high refractive materials. Substrate- free pearlescent pigment flakes are however also encompassed by the invention.

In a preferred embodiment, the pearlescent pigment flakes have several layers of materials with different refractive indexes, wherein low refractive index material, such as mica, silica, alumina or glass, is used as substrate and wherein the substrate is coated with a material of a higher refractive index.

Aspect ratio and thickness of the pigment flakes

The terms 'flake'’ or 'platelet’ as used herein refers to the shape of pigments having a large surface area and a small thickness. Typically, flakes or platelets are characterized by their 'aspect ratio’ , being defined as the largest dimension, i.e. the largest diameter of the surface, divided by the smallest dimension, i.e. the thickness.

In a preferred embodiment, the pigment flakes as used herein have a thickness smaller than 1 m and an aspect ratio (flake diameter/thickness) of at least 10.

In a preferred embodiment, the thickness of the pigment flakes is between 10 nm and 950 nm, more preferably between 15 nm and 850 nm, even more preferably between 50 nm and 650 nm. In another preferred embodiment, the thickness of the pigment flakes is between 10 nm and 200 nm, such as between 10 nm and 150 nm, between 10 nm and 100 nm or between 10 and 50 nm.

In another preferred embodiment, the thickness of the pigment flakes is between 200 nm and 980 nm, such as between 300 nm and 980 nm, between 400 nm and 980 nm or between 500 nm and 980 nm.

The pigment flakes as used herein preferably have an aspect ratio of at least 12, preferably at least 15, more preferably at least 20, even more preferably at least 30.

In an embodiment, the pigment flakes as used herein have an aspect ratio of between 10 and 500, preferably between 15 and 250, more preferably between 20 and 100.

Median diameter of the pigment flakes

In a preferred embodiment, the median diameter of the pigment flakes is 1.5 - 65 pm, more preferably 2 - 50 pm, even more preferably 3 - 40 pm, such as 4 -35 pm, or 5 - 30 pm.

In another preferred embodiment, the median diameter of the pigment flakes is 1 - 65 pm, such as 1 - 50 pm, 1 - 40 pm, 1 - 35 pm, 1 - 25 pm, 1 - 20 pm, 1 - 15 pm or 1 - 13 pm.

In yet another preferred embodiment, the median diameter of the pigment flakes is 2 - 75 pm, such as 5 - 75 pm, 10 - 75 pm, 15 - 75 pm, 20 - 75 pm, 25 - 75 pm, 30 - 75 pm or 35 - 75 pm.

Types of pigment flakes

In a preferred embodiment, the pigment flakes as defined herein are chosen from (I), (II), (III) or a combination thereof:

(I) Metal flakes or mica flakes, optionally coated with at least one layer of one or more components chosen from the group consisting of metal oxides, metals, metal sulphides, titanium suboxides, titanium oxynitrides, FeO(OH), SiCh, B2O3, GeCh, MgF2, metal alloys, rare earth compounds, and optionally coated with an outer layer comprising one or more colorants and a binder;

(II) Flakes comprising AI2O3, SiCh, glass, ceramics, graphite or mica platelets coated with at least one layer of one or more components chosen from the group consisting of metal oxides, metals, metal sulphides, titanium suboxides, titanium oxynitrides, FeO(OH), SiCh, B2O3, GeCh, metal alloys, rare earth compounds, and optionally coated with an outer layer comprising one or more colorants and a binder; and

(III) Flakes comprising AI2O3 platelets doped with one or more components chosen from the group consisting of TiC , ZrC , SiCh, SnC , ImCh, ZnO and iron oxide, coated with at least one layer of one or more components chosen from the group consisting of metal oxides, metals, metal sulphides, titanium suboxides, titanium oxynitrides, FeO(OH), SiCh, B2O3, GeCh, metal alloys, rare earth compounds, and optionally coated with an outer layer comprising one or more colorants and a binder.

In a preferred embodiment, the pigment flakes are synthetic pigment flakes. As will be appreciated by those skilled the art, the term 'synthetic' in 'synthetic pigment flakes' means that the pigment flakes are not pigment flakes naturally occurring, but they are pigment flakes that have been chemically manufactured or naturally occurring pigment flakes that have been chemically/physically processed to alter their properties. One of the advantages of using synthetic pigment flakes is that they can be produced with very smooth surfaces and high aspect ratios, thereby increasing their reflective properties.

Pigment flakes (I) can have zero to multiple coating layers, such as 1, 2, 3, 4 or 5 coating layers. In an embodiment, the metal in the metal pigment flakes (I) is chosen from the group consisting of aluminium, silver and gold, preferably aluminium. In an embodiment, metal pigment flakes (I) are aluminium flakes without any coating. In an embodiment, pigment flakes (I) are mica flakes without any coating. In an embodiment, pigment flakes (I) are mica flakes with several coating layers, such as mica flakes coated with TiO2, Fe2O3 and SnO2-

In an embodiment, metal pigment flakes (I) are aluminium pigment flakes coated with at least one layer of one or more components chosen from the group consisting of metal oxides, SiO2, B2O3, and GeO2. In an embodiment, metal pigment flakes (I) are aluminium flakes coated with an SiO2 layer.

In an embodiment, flakes (I) are coated with a SiO2 layer and with an outer layer comprising one or more colorants and a binder for fixation of the one or more colorants.

Examples of metal oxides that can be applied in a coating layer on metal pigment flakes (I) are chosen from the group consisting of TiO2, ZrO2, SnO2, ZnO, Mn02, MgO, Ce2O3, Fe2O3, Fe3O4, FeTiOs, Cr2O3, CoO, CO3O4, VO2, V2O3, NiO and combinations thereof. Examples of suitable aluminium pigment flakes (I) coated with (i) a first layer consisting of SiCh, B2O3, MnCh, MgO, GeCh or AI2O3, (ii) a second Fe2O3 layer on top of the first layer and optionally (iii) a third layer of TiCh, ZrCh, or AI2O3 on top of the second layer are disclosed in US2019/044679A1, which is incorporated herein by reference in its entirety.

Pigment flakes (II) and (III) can have one to multiple coating layers, such as 2, 3, 4 or 5 coating layers.

Examples of metal oxides that can be applied in a coating layer on metal pigment flakes (I) are chosen from the group consisting of TiCh, ZrCh, SnCh, ZnO, MnCh, MgO, Ce2O3, Fe2O3, Fe3O4, FeTiOs, CT2O3, CoO, CO3O4, VO2, V2O3, NiO and combinations thereof.

In an embodiment, pigment flakes (II) comprise glass platelets, wherein the glass is borosilicate glass. In an very preferred embodiment, pigment flakes (II) comprise AI2O3 platelets.

In an embodiment, pigment flakes (II) or (III) are coated with one or more layers of metal oxide, such as with at least one layer of metal oxide chosen from the group consisting of TiO2, ZrO2, SnO2, ZnO, Mn02, MgO, Ce2O3, Fe2O3, Fe3O4, FeTiOs, Cr2O3, CoO, CO3O4, VO2, V2O3, NiO and combinations thereof. In preferred embodiments, pigment flakes (II) or (III) are coated with one or more layers of metal oxide chosen from the group consisting of TiO2, Fe2O3, Fe3O4, SnO2, ZrO2, CnCh and combinations thereof, such as coated with one layer of metal oxide chosen from the group consisting of TiCh, Fe2O3 and a combination thereof.

Examples of pigment flakes (II) comprising AI2O3 platelets coated with different layers of metal oxide, SiCh and an organic dye as a top coat are disclosed in EP2799398B1, which is incorporated herein by reference in its entirety.

Examples of pigment flakes (II) comprising AI2O3 platelets coated with metal oxide chosen from the group consisting of TiCh, Fe2O3 and a combination thereof, and their preparation are disclosed in US 626781 OBI, which is incorporated herein by reference in its entirety. In another embodiment, pigment flakes (II) or (III) are coated with a layer of titanium suboxides (Ti _n O2n-i, with n being an integer greater than 1, such as the oxides Ti Os, TiaOa), with a layer of titanium oxynitrides, with a layer of FeO(OH), or with a thin semitransparent metal layer, for example comprising Al, Fe, Cr, Ag, Au, Pt or Pd, or combinations thereof.

In yet another embodiment, pigment flakes (II) or (III) are coated with a layer of a metal sulfide, such as coated with sulfides of tungsten, molybdenum, cerium, lanthanum or rare earth elements.

In another embodiment, pigment flakes (II) or (III) are coated with an outer layer of one or more colorants, for example Prussian Blue or Carmine Red, and a binder for fixation of the colorant.

As will be appreciated by those skilled in the art, these different layers can be combined, provided that the layer of one or more colorants and a binder is, if present, always an outer layer.

Examples of pigment flakes (III) comprising platelets of AI2O3 doped with titanium oxide and coated with metal oxide and their manufacture are disclosed in EP0763573B1, which is incorporated herein by reference in its entirety.

Examples of pigment flakes (III) comprising platelets of AI2O3 doped TiCh, ZrCb, SiCh, SnC , ImCh or ZnO and coated with metal oxide are disclosed in EP2799398B1, which is incorporated herein by reference in its entirety.

Ratio diameter pigment flakes to diameter spherical glass beads

The inventors have found that retroflection and LIDAR-detectability improves at higher ratios of the median diameter of the pigment flakes to the median particle diameter D50 of the spherical glass beads.

In a preferred embodiment, the median diameter of the pigment flakes is greater than 35% of the median particle diameter D50 of the spherical glass beads, more preferably greater than 38%, such as greater than 40%, greater than 45%, greater than 50%, greater than 55%, greater than 60%, greater than 70%, greater than 90%, greater than 110% or greater than 130%. In another preferred embodiment, the median diameter of the pigment flakes is between 35 and 400% of the median particle diameter D50 of the spherical glass beads, more preferably between 40 and 400%, such as between 45 and 400%, between 50 and 400%, between 55 and 400%, between 60 and 400%, between 70 and 400%, between 90 and 400%, between 110 and 400% or between 130 and 400%.

In yet another embodiment, the median diameter of the pigment flakes is between 35 and 350% of the median particle diameter D50 of the spherical glass beads, more preferably between 35 and 300%, such as between 35 and 250%, between 35 and 225%, between 35 and 200%, between 35 and 175%, between 35 and 150%, between 35 and 125%, between 35 and 100% or between 35 and 75%.

Amount of pigment flakes

In a preferred embodiment, the amount of said pigment flakes is 0.15 - 13 wt.%, based on the weight of the three-dimensional plastic product (1), such as 0.3 - 10 wt.%, 0.5 - 7.5 wt.%, 0.8 - 7 wt.%, 0.9 - 6.5 wt.% or 1 - 6 wt.%.

In an embodiment, the amount of said pigment flakes is 0.1 - 14 wt.%, based on the weight of the three-dimensional plastic product (1), such as 0.1 - 12 wt.%, 0.1 - 10 wt.%, 0.1 - 8 wt.%, 0.1 - 5 wt.% or 0.1 - 4 wt.%.

In another embodiment, the amount of said pigment flakes is 0.2 - 15 wt.%, based on the weight of the three-dimensional plastic product (1), such as 0.5 - 15 wt.%, 1 - 15 wt.%, 2 - 15 wt.%, 3 - 15 wt.% or 4 - 15 wt.%.

The amount of said pigment flakes is preferably 1 part by weight to between 1 and 80 part by weight of the spherical glass beads, preferably 1 part by weight to between 1 and 40 part by weight of the spherical glass beads, more preferably 1 part by weight to between 1 and 30 part by weight of the spherical glass beads.

Further ingredients

As defined hereinbefore, the three-dimensional plastic product (1) comprises 0 - 15 wt.% of one or more further ingredients, based on the weight of the three-dimensional plastic product (1). As will be appreciated by the skilled person, the 'further' ingredients are different from the other ingredients defined in the three-dimensional plastic product (1). In other words, the one or more further ingredients do not comprise said polymer (thermoplastic or thermoset), said spherical glass beads and said pigment flakes.

In a preferred embodiment, the one or more further ingredients do not comprise one or more of:

• spherical glass beads that are hemispherically coated with a light-reflective coating;

• spherical glass beads with a refractive index, measured at a wavelength of 589 nm, of 1.93 or lower; and

• spherical glass beads that are coated with a material which is repellent to the polymer.

The one or more further ingredients can encompass any additive that is typically used in plastic products. In an embodiment, the further ingredients are chosen from the group consisting of rheology modifiers, foam control agents, luminescent agents, UV-absorbers, plasticizers, reinforcement fibers, preservatives, dyes, curing initiators, organic pigments, inorganic pigments other than the metallic pigment flakes and pearlescent pigment flakes, and combinations thereof. Examples of reinforcement fibres are glass, carbon, aramid and basalt fibres.

In an embodiment, the amount of the one or more further ingredients is 0.01 - 15 wt.%, 0.02 - 13 wt.%, 0.05 - 11 wt.%, 0.1 - 10 wt.%, 0.2 - 9 wt.%, 0.25 - 8 wt.%, 0.30 - 7 wt.% or 0.35 - 6 wt.%, based on the weight of the three-dimensional plastic product (1).

In another embodiment, the amount of the one or more further ingredients is 0 - 14 wt.%, 0 - 13 wt.%, 0 - 12 wt.%, 0 - 11 wt.%, 0 - 10 wt.%, 0 - 9 wt.%, 0 - 8 wt.% or 0 - 7 wt.%, based on the weight of the three-dimensional plastic product (1).

In yet another embodiment, the amount of the one or more further ingredients is 0.02 - 15 wt.%, 0.05 - 15 wt.%, 0.1 - 15 wt.%, 0.2 - 15 wt.%, 0.25 - 15 wt.%, 0.30 - 15 wt.% or 0.35 - 15 wt.%, based on the weight of the three-dimensional plastic product (1).

Modified three-dimensional product (2)

The three-dimensional plastic product (1) according to the first aspect consists of the composition as defined hereinbefore. It can be used as an intermediate in the production of a modified three-dimensional product (2) wherein one or more further parts or components (3) are attached thereto. In a second aspect, the invention concerns a modified three-dimensional product (2) comprising:

• one or more three-dimensional plastic products (1) according to the first aspect and one or more further parts or components (3) attached thereto; or

• one or more further parts or components (3) and one or more three-dimensional plastic products (1) according to the first aspect attached thereto, with the proviso that at least part of the one or more outer retroreflective surface parts (C) of the three-dimensional plastic products (1) according to the first aspect is not covered by the one or more further parts or components (3).

Accordingly, one or more of the three-dimensional plastic products (1) according to the first aspect can be part of a modified three-dimensional product (2), thereby providing retroreflectivity and/or LIDAR-detectability to that modified product. As an example, the three- dimensional plastic product (1) according to the first aspect is a bumper that is part of a vehicle, the vehicle being the modified three-dimensional product (2).

The one or more further parts or components (3) are not necessarily made of plastic. For example, in case the modified three-dimensional product (2) is a car and the three-dimensional plastic products (1) are two mirror housings, the one or more further parts or components (3) attached to the two mirror housings are the remaining car parts, such as rubber tyres, a metal coachwork and chassis, et cetera.

In a preferred embodiment, the modified three-dimensional product (2) comprises the three-dimensional plastic product (1) according to the first aspect of which part is coated with one or more coating layers, the one or more coating layers being one or more further parts or components (3).

In a preferred embodiment, the modified three-dimensional product (2) is a vehicle part, more preferably an automotive body part, such as an automotive body part chosen from the group consisting of bumpers, mirror housings, handles, radio antennae and skirting.

In a very preferred embodiment, the modified three-dimensional product (2) is a vehicle, more preferably a vehicle chosen from the group consisting of cars, lorries, trucks, bikes, mopeds, scooters, motorcycles, trains, trams, boats, ships, drones, skateboards, missiles, helicopters and aircrafts, even more preferably a vehicle chosen from cars, lorries, trucks, bikes, mopeds, scooters and motorcycles.

Process for producing the three-dimensional plastic product (1)

A third aspect of the invention concerns a process for producing the three-dimensional plastic product (1) with retroreflective properties according to the first aspect, wherein the polymer is a thermoplastic polymer, said process comprising the steps of:

(a) providing the thermoplastic polymer, the spherical glass beads, the pigments flakes and the optional further ingredients;

(b) compounding the ingredients provided in step (a) at a temperature above the melting point of the thermoplastic polymer;

(c) providing the mixture obtained in step (b) into a mould or extruding the mixture obtained in step (b); and

(d) cooling the mixture in the mould to a temperature below the melting point of the thermoplastic polymer and removing the three-dimensional plastic product (1) with retroreflective properties from the mould or cooling the extrudate to a temperature below the melting point of the thermoplastic polymer to provide the three-dimensional plastic product (1) with retroreflective properties.

In an embodiment, the process according to the third aspect is performed in an extruder and an injection moulding machine. It is within the skills of the artisan, to choose appropriate process conditions.

As will be appreciated by those skilled in the art, step (b) of compounding the ingredients can be performed in more than one step. One can for example first prepare a masterbatch of polymer and spherical glass beads, e.g. in filament or pellet form, and then compound this masterbatch with pigment flakes, the optional one or more further ingredients and optional additional polymer.

A fourth aspect of the invention concerns a process for producing the three-dimensional plastic product (1) with retroreflective properties according to the first aspect, wherein the polymer is a thermoset polymer, said process comprising the steps of: (a) providing a thermoset curable resin, the spherical glass beads, the pigments flakes and the optional further ingredients;

(b) mixing the ingredients provided in step (a);

(c) providing the mixture obtained in step (b) into a mould;

(d) curing the mixture in the mould to provide the three-dimensional plastic product (1) with retroreflective properties; and

(e) removing the three-dimensional plastic product (1) with retroreflective properties from the mould.

In an embodiment, the process according to the fourth aspect is performed in an injection moulding machine. It is within the skills of the artisan, to choose appropriate process conditions.

As described hereinbefore, the one or more outer retroreflective surface parts (C) of the three-dimensional plastic product (1) can be smooth or have a glossy or semi-glossy appearance, wherein the spherical glass beads are fully embedded in the polymer matrix. Such a three-dimensional plastic product (1) can be produced using a mould with smooth internal surfaces in the processes according to the third or fourth aspect. The one or more outer retroreflective surface parts (C) of the three-dimensional plastic product (1) can also be rough or have a matte appearance, wherein the spherical glass beads protrude from the surface but are still covered by the polymer matrix. Such a three-dimensional plastic product (1) can be produced using a mould with rough internal surfaces in the processes according to the third or fourth aspect.

Process for producing the modified three-dimensional product (2)

As will be appreciated by those skilled in the art, the modified three-dimensional product (2) as defined hereinbefore can be produced by providing one or more three-dimensional plastic products (1) according to the first aspect and one or more further parts or components (3) and by assembling them, connecting them or putting them together.

If the one or more further parts or components (3) are also plastic components, such as for example thermoplastic polymers, the modified three-dimensional product (2) as defined hereinbefore can be produced by co-extrusion of (i) a melt of the polymer, the spherical glass beads, the pigments flakes and the optional further ingredients as defined in the context of the first aspect in the relative amounts as defined in the context of the first aspect and (ii) one or more further polymers that are to form the one or more further plastic parts or components (3).

As will be appreciated by those skilled in the art, a modified three-dimensional product (2) comprising one or more three-dimensional plastic products (1) according to the first aspect and one or more further plastic parts or components (3) produced using co-extrusion can in turn be provided with further parts or components (3) to provide another modified three-dimensional product (2).

Laser Imaging Detection And Ranging (LIDAR) process

A fifth aspect of the invention concerns a Laser Imaging Detection And Ranging (LIDAR) process of the three-dimensional plastic product (1) according to the first aspect or of the modified three-dimensional product (2) according to the second aspect, said process comprising the steps of:

(i) providing a LIDAR device comprising a source of electromagnetic radiation, a receiver and optionally a Global Positioning System (GPS);

(ii) transmitting electromagnetic radiation from the source of electromagnetic radiation of the LIDAR device to the three-dimensional plastic product (1) or to the modified three- dimensional product (2);

(iii) scanning the electromagnetic radiation reflected by the three-dimensional plastic product (1) or by the modified three-dimensional product (2) with the receiver of the LIDAR device; and

(iv) computing from the differences between the transmitted electromagnetic radiation and the scanned reflected electromagnetic radiation, preferably as a function of time, one or more of:

• the distance between the three-dimensional plastic product (1) or the modified three-dimensional product (2) and the LIDAR device;

• the acceleration of the three-dimensional plastic product (1) or of the modified three-dimensional product (2);

• the deceleration of the three-dimensional plastic product (1) or of the modified three-dimensional product (2);

• the direction of movement of the three-dimensional plastic product (1) or of the modified three-dimensional product (2); • the speed of the three-dimensional plastic product (1) or of the modified three- dimensional product (2), preferably the speed relative to that of the LIDAR device; and

• a 3D image of the three-dimensional plastic product (1) or of the modified three- dimensional product (2).

As will be appreciated by those skilled in the art, computing the speed, acceleration, deceleration and direction of movement of the three-dimensional plastic product (1) or of the modified three-dimensional product (2) requires that steps (ii) and (iii) are performed as a function of time.

If the LIDAR device is also equipped with a GPS, the distance between the three- dimensional plastic product (1) or of the modified three-dimensional product (2) and the LIDAR device can also be indicated on a map and the 3D image of the three-dimensional plastic product (1) or of the modified three-dimensional product (2) can be identified on a map.

In a preferred embodiment, the electromagnetic radiation transmitted and scanned in steps

(ii) and (iii), respectively, has a wavelength between 740 and 2500 nm, more preferably a wavelength between 750 and 1800 nm, even more preferably a wavelength between 780 and 1600 nm, such as 905 nm or 1550 nm.

In an embodiment, the electromagnetic radiation transmitted and scanned in steps (ii) and

(iii), respectively, has a wavelength between 740 and 2200 nm, such as between 740 and 2000 nm, between 740 and 1800 nm, between 740 and 1700 nm, between 740 and 1650 nm or between 740 and 1600 nm.

In another embodiment, the electromagnetic radiation transmitted and scanned in steps (ii) and (iii), respectively, has a wavelength between 750 and 2500 nm, such as between 780 and 2500 nm, between 800 and 2500 nm, between 825 and 2500 nm, between 850 and 2500 nm and between 875 and 2500 nm.

Uses

In a sixth aspect, the invention concerns the use of the three-dimensional plastic product (1) according to the first aspect in the form of a filament or pellet, wherein the polymer is a thermoplastic polymer, in the production of a ready-to-use three-dimensional plastic product (1) according to the first aspect, wherein the polymer is a thermoplastic polymer. In a seventh aspect, the invention concerns the use of the three-dimensional plastic product (1) according to the first aspect or of the modified three-dimensional product (2) according to the second aspect,

• in Laser Imaging Detection And Ranging (LIDAR) of said three-dimensional plastic product (1) or of said modified three-dimensional product (2); and/or

• to improve the visibility of said three-dimensional plastic product (1) or of said modified three-dimensional product (2) under visible light conditions; and/or

• to prepare a three-dimensional image of said three-dimensional plastic product (1) or of said modified three-dimensional product (2).

Thus, the invention has been described by reference to certain embodiments discussed above. It will be recognized that these embodiments are susceptible to various modifications and alternative forms well known to those of skill in the art.

Furthermore, for a proper understanding of this document and its claims, it is to be understood that the verb ‘to comprise'’ and its conjugations are used in its non-limiting sense to mean that items following the word are included, but items not specifically mentioned are not excluded. In addition, reference to an element by the indefinite article ‘a’ or ‘an’ does not exclude the possibility that more than one of the element is present, unless the context clearly requires that there be one and only one of the elements. The indefinite article ‘a’ or ‘an’ thus usually means ‘at least one’ .

EXAMPLES

Materials

Spherical glass beads

• Micro glass beads (C), obtained from Jianxi Sunflex Light Retroreflective Material Co, Ltd., China, having a refractive index of about 2.2, measured at a wavelength X of 589 nm, having a median particle diameter D50 of about 40.37 pm, a DIO diameter of 37.32 pm and a D90 diameter of 44.11 pm, as measured with laser diffraction.

• Micro glass beads (CS), obtained from Jianxi Sunflex Light Retroreflective Material Co, Ltd., China, having a refractive index of about 2.2, measured at a wavelength X of 589 nm, having a median particle diameter D50 of about 27.49 pm, a DIO diameter of 20.64 pm and a D90 diameter of 33.24 pm, as measured with laser diffraction.

• Micro glass beads (CSS), obtained from Jianxi Sunflex Light Retroreflective Material Co, Ltd., China, having a refractive index of about 2.2, measured at a wavelength X of 589 nm, having a median particle diameter D50 of 22.00 pm, a D10 diameter of 16.33 pm and a D90 diameter of 26.21 pm, as measured with laser diffraction.

• Micro glass beads (CSTL), obtained from Swarco, Austria, having a refractive index of about 2.1, measured at a wavelength X of 589 nm, having a median particle diameter D50 of 7.80 pm, a D10 diameter of 3.27 pm and a D90 diameter of 20.2 pm, as measured with laser diffraction.

• HAC-coated micro glass beads (CSX), obtained from Jianxi Sunflex Light Retroreflective Material Co, Ltd., China, having a refractive index of about 2.2, measured at a wavelength X of 589 nm, having a median particle diameter D50 of 26.46 pm, a D10 diameter of 22.94 pm and a D90 diameter of 29.57 pm, as measured with laser diffraction.

• HAC-coated micro glass beads (NSX), obtained from Jianxi Sunflex Light Retroreflective Material Co, Ltd., China, having a refractive index of about 1.9, measured at a wavelength X of 589 nm, having a median particle diameter D50 of 26.13 pm, a D10 diameter of 19.51 pm and a D90 diameter of 31.41 pm, as measured with laser diffraction.

Polymers

Polypropylene homopolymer (PP), obtained from Sabie

Polystyrene pellets (PS), obtained from Total Low-density polyethylene (LDPE) granules, obtained from Sabie

High-density polyethylene (HDPE) pellets, obtained from Lyondell Basell

Further ingredients

• Pigment White 6

• U.5.103 l.m Blue

• PO72 - orange pigment

• PZ125 black

• PZ810/50 black

• SINLOIHI FZ-6014 Orange, obtained from Sinloihi Co., Ltd., Japan (‘SINL.’)

Pigment flakes

• KCPP® KC123, obtained from Kuncai Americas, (Mica, TiO2 and SnO2), pearlescent effect pigment in silver white shade, 5-30 pm,

• Xillamaya T60-23 SW Galaxy Blue, obtained from Fujian Kuncai Material Technology, synthetic mica pearlescent pigment flakes, 6-30 pm

• Xillamaya T60-10 SW, obtained from Fujian Kuncai Material Technology, (synthetic fluorphlogopite, TiO2, SnO2, SiO2, Ce2O3), D50 diameter 14.5 pm (‘Xillam.’)

• Iriodin® 9307 Star Gold SW, obtained from Merck KGaA, (Mica, TiO2, SiO2, Fe2O3 and SnO2, auxiliaries), D50 diameter between 21 and 26 pm

• Mastersafe MP 35-20B, obtained from Eckart GmbH, aluminium pigment flakes, D50 diameter 35 pm

• KC 8200 10-45 pm, obtained from Fujian Kuncai Material Technology, (synthetic fluorphlogopite, TiO2), D50 diameter 20.0 pm

• Xirallic® NXT M260-70 SW Amur Black, obtained from Merck KGaA, (Fe3O4, AI2O3, SiO2, auxiliaries), D50 diameter between 17 and 23 pm

• Alegrace® Aurous B 21/11-1 Yellow Gold flakes, obtained from Schlenk Metallic Pigments, 8-38 pm

• Aluminium paste Chromos GN/08-01, obtained from Schlenk Metallic Pigments GmbH, surface-treated aluminium pigment flakes, D50 diameter of 8 pm

• Zenexo® Copperglow WB 21 GO, obtained from Schlenk Metallic Pigments GmbH, D50 diameter of 21 pm • Zenexo® Golden Shine WB 21 YY, obtained from Schlenk Metallic Pigments GmbH, D50 diameter of 21 |im

• Mastersafe MP 68-20B, aluminium pigment flakes, obtained from Eckart GmBH, D50 diameter 68 pm (‘Master.’)

• STAPA PP REFLEXAL 1032/80, aluminium silverdollar pigment, obtained from Eckart GmBH, D50 diameter of 10 pm (‘STAPA’)

• Grandal® P 3600, obtained from Carl Schlenk AG, D50 diameter of 31 pm (‘P3600’)

Example 1: preparation of three-dimensional coloured plastic products

Eighteen three-dimensional coloured plastic products were prepared as follows from the ingredients indicated in Table 1 and Table 2.

First, mono-concentrates were prepared by adding the relevant plastic pellets (PP or LDPE) to a twin screw extruder (Noris ZSC 20), by heating to melt the polymer, by adding the relevant glass beads to the melted plastic mixture via a side feeder, followed by thorough mixing. The resulting strands were cooled and pelletized to become mono-concentrates.

In a second step, the mono-concentrates were used in combination with different colour pigments and pigments flakes in different concentrations to provide 18 final formulations (see Table 1 and Table 2 for the overall compositions of the 18 final formulations). These final formulations were made using a single screw extruder (Noris ESE30), by adding the relevant mono-concentrate, the relevant colour pigment and pigment flakes and optionally additional polymer (PP or LDPE). The mixture of components was roughly blended by handshake/stir for 1 minute and added to the extruder, to be heated, melted and mixed at increased temperature. The resulting strands were cooled and pelletized into final formulation product pellets.

In a third step, the relevant final formulation product pellets were added to an injection moulding machine (ALLROUNDER 320 C 500 - 100) to be extruded after heating into a mirror like mould form to produce plastic products with a length of 10 cm, a width of 5 cm and 3 areas of different thicknesses (2 mm, 3 mm and 4 mm) in the direction of the length. All three- dimensional coloured plastic products, i.e. including those comprising spherical glass beads, had very smooth outer surfaces. The glass beads did not protrude from the outer surfaces, i.e. the surfaces were ungrained. Table 1: overall compositions final formulations / products

Table 2: overall compositions final formulations / products

Example 2: assessment of retroreflective properties and LJDAR-detectabilit

The general (off centre) retroreflection of the 18 three-dimensional coloured plastic products produced in Example 1 was visually inspected and assessed by directing the beam of a torch under an angle of 30° with the axis perpendicular to the main surface of the three- dimensional coloured plastic products, wherein the sightline of the eyes substantially coincides with the beam of the torch, and by visually determining whether or not and to which extent retroreflection is observed.

The qualification ‘1’ means very little to no retroflection at all and the qualification ‘4’ means very good retroreflection. Details are presented in Table 3. As can be inferred from Table 3, retroreflection is much better for the three-dimensional coloured plastic products according to the invention than for the comparative products. The retroflection of the surfaces of the three- dimensional coloured plastic products according to the invention is good to very good.

LIDAR-detectability was determined by scanning the surface of the eighteen three- dimensional coloured plastic products produced in Example 1 with a Li vox Tele- 15 LIDAR- device (Livox Technology Company Co., Ltd) at a wavelength of 905 nm under an angle of about 30° with the axis perpendicular to the main surface. Scanning took place under daylight conditions. The Tele-15 LIDAR device was placed at a distance of about 20 meters from the main surface of the three-dimensional coloured plastic products. The Tele- 15 LIDAR-device calculates reflectivity values for different areas of the main surface of the three-dimensional coloured plastic products that is scanned, based on the ratio of reflected laser energy over incident laser energy, and generates a point cloud from these data. Every point in the point cloud has a corresponding reflectivity value. The reflectivity values obtained for each three- dimensional coloured plastic product were ordered form low to high and the highest value was taken as the reflectivity score (reference value) for that product. Since all products scanned were identical as regards form and since they were scanned under the same angle at the same distance, their LIDAR-detectability can be compared by comparing their reflectivity scores. Reflectivity scores thus obtained are indicated in Table 3.

As can be inferred from Table 3, LIDAR-detectability is much better for the three- dimensional coloured plastic products according to the invention than for the comparative products. Table 3: retroreflection and LIDAR-detectability

Example 3: production of three-dimensional plastic products

Three-dimensional plastic products were prepared as follows. In a first step, 5 mono- concentrates (MCI to MC5) were prepared, having the recipes presented in Table 4.

Table 4: compositions mono-concentrates (MCI to MC5

The mono-concentrates were prepared by adding the relevant plastic pellets to a twin screw extruder (Noris ZSC 20), heating to 150 °C (LDPE) or 200 °C (PS), and by adding via a side feeder the relevant glass beads to the melted plastic mixture, followed by thorough mixing.

The resulting strands were cooled and pelletized to become mono-concentrates.

In a second step, the mono-concentrates were used in combination with different colour pigments and pigment flakes, in different concentrations, and in different combinations to provide 43 final formulations (VI to V43). These final formulations were made using a single screw extruder (Noris ESE30), by adding the relevant mono-concentrate(’s), the relevant pigment/pigment flakes and sufficient additional High Density Poly Ethylene (HDPE) or Polystyrene (PS). The mixture of components was roughly blended by handshake/stir for 1 minute and added to the extruder to be heated, melted and mixed at 200 °C. The resulting strands were cooled and pelletized into final formulation product pellets.

In a third step, the relevant final formulation product pellets were added to an injection moulding machine (ALLROUNDER 320 C 500 - 100) to be extruded after heating to 200 °C- 220 °C into a mirror like mould form to produce three-dimensional plastic products with a length of 10 cm, a width of 5 cm and 3 areas of different thicknesses (2 mm, 3 mm and 4 mm) in the direction of the length. All three-dimensional plastic products, i.e. including those comprising spherical glass beads, had very smooth outer surfaces. The glass beads did not protrude from the outer surfaces, i.e. the surfaces were ungrained.

The recipes of the 43 final formulations VI to V43 are shows in Table 5.

Table 5: final formulations VI to V43

Example 4: Comparative Examples according to the prior art

Final formulation V40 is in accordance with Example 1 of W02005/033194A1. Final formulation V41 is in accordance with comparative Example A of W02005/033194A1. The formulations in the examples of W02005/033194A1 comprise HAC-coated BaTiO microspheres of 38 pm and uncoated BaTiO microspheres of 8.5 pm, obtained from Prizmalite Industries. As explained hereinbefore, the spherical glass beads used in W02005/033194A1 have a refractive index of 1.9. Final formulation V40 and V41, however, comprise uncoated microspheres of 7.8 pm having a refractive index of 2.1. This does, however, not influence the conclusions that can be drawn from the results.

See below Table 6 summarizing the recipes. According to the example of W02005/033194A1, the retroreflection of an ungrained surface of a product produced from final formulation V40 was about 30 to 50% higher than the retroreflection of an ungrained surface of a product produced from final formulation V41, according to the "qualitative view by those of ordinary skill in the art'’ .

Retroreflection of the three-dimensional plastic products produced from final formulation V40 and V41 (both not in accordance with the invention) was visually assessed with torch light under an angle of 45° with the axis perpendicular to the main surface of the plastic products. The viewing angle was along the direction of the torch light, i.e. also under an angle of 45° with the axis perpendicular to the main surface of the three-dimensional plastic products. It was concluded from the visual assessment that ungrained surfaces of the three-dimensional plastic product produced from final formulation V40 (in accordance with Example 1 of W02005/033194A1) instead of being 30 to 50% better showed less retroreflection than ungrained surfaces of the three-dimensional plastic product produced from final formulation V41 (in accordance with Comparative Example A of W02005/033194A1). See Table 6.

Moreover, both the ungrained surfaces of the three-dimensional plastic product produced from final formulation V40 and produced from final formulation V41 showed insufficient retroreflection under an angle of 45° to be of any relevance. This result would have been even worse when final formulations V40 and V41 had contained a carbon black pigment (as applied in Example 1 and Comparative Example A of W02005/033194A1).

Table 6 also summarizes the recipes of final formulations V15, V17 and V35. Retroreflection of the three-dimensional plastic products produced from final formulations V15, V17 and V35 (all in accordance with the invention) was also visually assessed with torch light under an angle of 45° with the axis perpendicular to the main surface of the three- dimensional plastic products. As shown in Table 6, the ungrained surfaces of the three- dimensional plastic products produced from final formulations VI 5, V 17 and V35 demonstrate considerably higher retroreflection than ungrained surfaces of the three-dimensional plastic products produced from final formulations V40 and V41.

LIDAR-detectability of the surfaces of the three-dimensional plastic products produced from final formulations V40, V41, V15, V17 and V35 was determined by scanning their main surfaces with a Livox Tele-15 LIDAR-device (Livox Technology Company Co., Ltd) at a wavelength of 905 nm under an angle of about 30° with the axis perpendicular to the main surface of the three-dimensional plastic products. Scanning took place under daylight conditions. The Tele-15 LIDAR device was placed at a distance of about 17 meters from the main surface of the three-dimensional plastic products.

The Tele- 15 LIDAR-device calculates reflectivity values for different areas of the surface that is scanned, based on the ratio of reflected laser energy over incident laser energy, and generates a point cloud from these data. Every point in the point cloud has a corresponding reflectivity value. The reflectivity values obtained for each three-dimensional plastic product were ordered form low to high and the highest value was taken as the reflectivity score (reference value) for that product. Since all products scanned were identical as regards form and since they were scanned under the same angle at the same distance, their LIDAR- detectability can be compared by comparing their reflectivity scores. Reflectivity scores thus obtained are indicated in Table 6.

It was concluded that the main surface of the three-dimensional plastic product produced from final formulation V40 (in accordance with Example 1 of W02005/033194A1) had lower LIDAR-detectability than the main surface of the three-dimensional plastic product produced from final formulation V41 (in accordance with Comparative Example A of W02005/033194A1). As shown in Table 6, the main surfaces of three-dimensional plastic products produced from final formulations V15, V17 and V35 demonstrate considerably higher LIDAR-detectability than the main surfaces of three-dimensional plastic products produced from final formulations V40 and V41. Table 6: retroreflection and LIDAR-detectability

Example 5: retroreflectivit and LIDAR-detectability of three-dimensional plastic products

Retroreflection and LIDAR-detectability of surfaces of three-dimensional plastic products produced from several final formulations chosen from VI to V43 were tested using the methods as defined in Example 4. The results of the retroreflection test are shown in Figure 7. Figure 7 shows the retroreflection of the surfaces of 20 products (4 rows, 5 columns). The characteristics of the different final formulations used in this test are briefly summarized in Table 7. Lidar reflectivity scores are also indicated in Table 7.

Table 7: characteristics final formulations

It can be concluded from a comparison of columns 2-5 in Figure 7 and in Table 7 that final formulations comprising uncoated spherical glass beads (CSS or CSTL) having a high refractive index of 2.2/2.1 combined with pigment flakes result in the highest retroreflection, whereas final formulations comprising HAC coated spherical glass beads (NSX or CSX) having refractive indices of 1.9 or 2.2 combined with pigment flakes hardly show any retroreflection. Accordingly, a HAC coating decreases retroreflection significantly in products wherein the spherical glass beads do not protrude from the polymer matrix. It can further be concluded from a comparison of columns 2-5 in Table 7 that final formulations comprising uncoated spherical glass beads (CSS or CSTL) having a high refractive index of 2.2/2.1 combined with pigment flakes result in much higher LIDAR-detectability than final formulations comprising HAC coated spherical glass beads (NSX or CSX) having refractive indices of 1.9 or 2.2 combined with pigment flakes in products wherein the spherical glass beads do not protrude from the polymer matrix.