PROCESSES FOR TEXTURIZING AND MARKING A SURFACE

Abstract

The present disclosure concerns texturing and/or marking a surface of a plastic article. more specifically processes for creating textures and marking onto a surface made of foamed plastic material to obtain different reflectivity or different shades by selectively modifying the roughness degree of the surface.

Claims

1. A process for texturizing a surface made of a thermoplastic polymeric material to obtain a textured surface having regions of different roughness, the process comprising: providing a foamed surface made of foamed thermoplastic polymeric material, the foamed surface having a first roughness grade; and melting the foamed thermoplastic material at one or more regions of the foamed surface to cause reduction of roughness in said one or more regions to a second roughness grade, thereby obtaining the textured surface, wherein said melting is obtained by contacting said foamed surface with at least one textured heated surface, said heated surface having a texture which has said second roughness grade, said textured heated surface is heated to a temperature of at least about 140 C.

2. (canceled)

3. (canceled)

4. The process of claim 1, wherein said textured heated surface comprises a pattern having at least two zones differing therebetween by roughness grade.

5. The process of claim 4, wherein said textured heated surface comprises first zones having said second roughness grade, and second zones having a third roughness grade smaller than said second roughness grade.

6. The process of claim 1, wherein said textured heated surface is a heated roller.

7. The process of claim 1, wherein said thermoplastic polymeric material is a composition comprising polypropylene or a copolymer thereof.

8. The process of claim 1, wherein said foamed thermoplastic polymeric material is obtained by exothermal foaming.

9. The process of claim 8, wherein said thermoplastic polymeric material is a composition of one or more thermoplastic polymers and one or more exothermal blowing agents, said exothermal foaming comprises exposing said composition to conditions permitting exothermal decomposition of said exothermal blowing agent to obtain said foamed thermoplastic polymeric material.

10. (canceled)

11. The process of claim 1, wherein said textured surface is a surface of an extruded article.

12. The process of claim 11, wherein said extruded article is made of said foamed thermoplastic polymeric material.

13. The process of claim 11, wherein said extruded article comprises a core made of a non-foamed thermoplastic material, and said surface is made of said foamed thermoplastic polymeric material.

14. (canceled)

15. The process of claim 11, wherein said extruded article comprises a core made of non-polymeric thermoplastic composition, coated by said foamed thermoplastic polymeric material.

16. The process of claim 13, wherein said extruded article is manufactured by co-extrusion of the foamed thermoplastic polymeric material onto the core.

17. The process of claim 1, further comprising digitally printing one or more printing inks over at least one region of the textured surface.

18. A process for providing an article having a textured surface comprising regions of different light reflectivity, the process comprising: providing a foamed surface made of foamed thermoplastic polymeric material to obtain a first light reflectivity of the surface; and melting the foamed thermoplastic material at one or more regions of the foamed surface to cause reduction in roughness in said one or more regions, thereby obtaining a second light reflectivity of said one or more regions, said second light reflectivity being larger than said first light reflectivity wherein said foamed surface has a first roughness grade, and said melting is obtained by contacting said foamed surface with at least one textured heated surface, said heated surface having a texture which has at least one second roughness grade, said heated surface comprising a pattern having at least two zones differing therebetween by roughness grade.

19. The process of claim 18, wherein said second light reflectivity is larger than said first light reflectivity by at least 20 Gloss Units (as measured according to ASTM D2457).

20. (canceled)

21. (canceled)

22. The process of claim 18, wherein said heated surface comprises first zones having said second roughness grade, and second zones having a third roughness grade smaller than said second roughness grade.

23. The process of claim 18, wherein said textured heated surface is a heated roller.

24. The process of claim 18, wherein said thermoplastic material is a composition comprising polypropylene or a copolymer thereof.

25. The process of claim 18, wherein said foamed thermoplastic polymeric material is obtained by exothermal foaming.

26. The process of claim 25, wherein the thermoplastic polymeric material is a composition of one or more thermoplastic polymers and one or more exothermal blowing agents, said exothermal foaming comprises exposing said composition to conditions permitting exothermal decomposition of said exothermal blowing agent to obtain said foamed thermoplastic polymeric material.

27. The process of claim 18, wherein said article is obtained by extrusion.

28. The process of claim 18, wherein said article is made of said foamed thermoplastic polymeric material.

29. The process of claim 18, wherein said article comprises a core made of a non-foamed thermoplastic material, and said surface is made of said foamed thermoplastic polymeric material.

30. The process of claim 29, wherein said article is obtained by co-extrusion.

31. (canceled)

32. (canceled)

33. (canceled)

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0051] In order to better understand the subject matter that is disclosed herein and to exemplify how it may be carried out in practice, embodiments will now be described, by way of non-limiting example only, with reference to the accompanying drawings, in which:

[0052] FIGS. 1A-1B are schematic illustrations of regular reflection and diffuse reflection of light from a surface, respectively.

[0053] FIGS. 2A-2B show extrusion molded polypropylene composition panels produced according to an embodiment of the process of this disclosure, where FIG. 2A shows the foamed surface of the panel, and FIG. 2B shows the finished panel after melting regions of the foamed surface to obtain a pattern.

[0054] FIG. 2C shows a textured heated roller utilized in a process according to an embodiment of this disclosure.

[0055] FIGS. 3A-3B illustrate the surface structure of an article produced according to a process of this disclosure (FIG. 3A) and a close-up thereof (FIG. 3B).

[0056] FIG. 4 illustrates an exemplary section of a heated textured roller utilized in an embodiment of a process according to this disclosure.

[0057] FIG. 5 shows an extrusion molded polypropylene composition panel without a foamed surface, onto which surface melting has been employed.

[0058] FIG. 6 shows an extruded wood-plastic composition (WPC) without a foamed surface, onto which high pressure mechanical embossing has been employed.

DETAILED DESCRIPTION OF EMBODIMENTS

[0059] As noted, the processes of this disclosure enable obtaining a textured surface of an article, with regions of different roughness and light reflectivity, to obtain various visual effects. As shown in FIGS. 1A-1B, the roughness of a surface impacts the shade of color perceived by a viewer. Regular reflection of light is obtained from smooth surfaces, in which incident rays of light impinging the surface are reflected in a parallel, ordered manner, as illustrated in FIG. 1A. In regular reflection, more reflected light arrives at the viewer's eye and hence the surface color is perceived by the user as being darker or of a dark shade. In comparison, a rougher surface, as illustrated in FIG. 1B, will cause incident rays of light to be reflected at different angles due to the irregularity of the surface (diffused reflection) and thus be perceived by the viewer as lighter or brighter shade.

[0060] Processes of this disclosure enable providing a surface with differences in roughness and/or light reflectance, thereby obtaining articles having a texturized or patterned surface, in which regions of the surface have different roughness, and hence different light reflectance which is perceived by the viewer as different color shades.

Example 1

[0061] Shown in FIG. 2A is a surface of a panel made by coextrusion of foamed thermoplastic polymeric material, in this specific example a composition comprising polypropylene as a main component and azodicarbonamide (ADC) as an exothermic blowing agent. The material temperature at the co-extruder was 170-220 C., and the material was maintained within the co-extruder for a pre-defined period of time before extruding through the extrusion die to allow the ADC to decompose and form the foamed external surface of the panel.

[0062] Following extrusion, the foamed surface of the panel was transported under a textured heated roller, an example of which is shown in FIG. 2C. As can be seen, regions of the roller, generally designated 102, were textured and caused transfer heat to the foamed surface at controlled manner. The roller was heated to a temperature of about 140 C., and when rolled over the foamed surface of the panel, local melting of the polypropylene was obtained, thereby smoothening the surface in these regions and imparting them with a roughness grade and texture according to that of regions 102. Hence, panel 100, as seen in FIG. 2B, has regions of a high roughness grade, generally designated 104 originating from the foaming (perceived by the viewer as having a lighter shade), and regions 106 of a smaller roughness grade (perceived by the viewer as having a darker shade) due to the melting and smoothing imparted by the textured heated roller.

[0063] As can clearly be seen in FIG. 2B, regions 106 are visibly darker than regions 104 due to the differences in roughness grades.

[0064] The light reflectance from the different regions was measured according to ASTM D2457. In regions 104 the light reflectance was at most 5 GU, while in regions 106 the light reflectance was at least 25 GU. While the panel had the same color along it entire surface, this difference in reflectance (caused by difference in roughness) caused regions 104, having a higher degree of roughness, to be perceived as having a lighter or duller shade compared to regions 106 who have a lesser roughness and are perceived as having a darker or glossier shade of the same color.

[0065] As clearly visible from FIGS. 2B, 3A and 3B, the process enables careful control of surface roughness, thereby enabling imparting the extruded panel with a desired texture, mimicking, in this specific example, a natural wood panel texture and grain at a high accuracy.

[0066] Seen in FIG. 4 is a close-up view of an illustrated section of the roller with an illustration of a corresponding profile 200 of the heated textured roller. Zones 202 of the roller have a roughness grade that is smaller than the roughness of the foamed surface of the panel, and protrude from the surface of the roller, such that zones 202 come into contact with the foamed surface of the panel when the roller is rolled over the surface. The pre-defined texture of zones 202 also enable to control the heat transfer to the surface of the panel once contact between the roller and the foamed surface to be textured is obtained, thereby avoiding over-melting the foamed surface and hindering the desired texture. As the roller is heated, the thermoplastic polymeric material constituting the surface of the panel undergo local melting, and are imparted with the roughness and texture of zones 202 to obtain regions 106 of a smaller roughness grade and darker shade. Zones 204 of the roller, however, constitute gaps between zones 202, in which the roller does not come into contact with the surface of the panel, leaving the original, higher roughness foamed texture untreated, thereby obtaining regions 104 having a lighter shade.

Example 2Reference Example

[0067] Seen in FIG. 5 is an extrusion panel 300 made of the same polypropylene composition of Example 1, however, without the blowing agent. This panel was treated by the heated textured roller of Example 1 under the same conditions to obtain a textured panel 300. As can be seen in FIG. 5, almost no difference in shade of color can be seen between regions 302, which constitute the original, smooth surface of the panel, and regions 304 which are the regions that came into contact with the heated roller.

Example 3Reference Example

[0068] Seen in FIG. 6 is an injection molded panel 400 made of the same polypropylene composition of Example 1, however, without the blowing agent. This panel was treated by high pressure and heated mechanical embossing. As can be seen in FIG. 6, while a pattern is visible on the surface of the panel, almost no difference in shade of color can be observed.