WO2005118293A1

WO2005118293A1 - Apparatus for printing on substrates of timber or synthetic material

Info

Publication number: WO2005118293A1
Application number: PCT/US2004/023677
Authority: WO
Inventors: Maximilian Zaher
Original assignee: Demaxz, L.L.C.
Priority date: 2004-05-21
Filing date: 2004-07-23
Publication date: 2005-12-15

Abstract

The present invention includes an engraved cylinder (18) with indentations for receipt of printing ink and an off set printing roller (16), onto which the printing ink is transferred from the engraved cylinder and from which the ink is transferred onto the substrate (10) . In one preferred embodiment, the printing roller (16) has a hardness at its surface softer than 20 on the Shore A scale.

Description

Apparatus for Printing on Substrates of Timber or Synthetic Material This application claims priority to U.S. Patent Application Serial No. 60/573,948 filed on May 21, 2004 which is incorporated by reference herein in its entirety. BACKGROUND OF INVENTION Technical Field The present invention relates to an apparatus and a method for the printing of substrates made from timber material or synthetic material. Objects of Invention One object of the present invention is to provide such an apparatus and method that make it possible to produce aesthetically and tangibly superior printed surfaces at a relatively low expense. In particular, the printed design should look natural and feel natural when, for example, a genuine timber surface or a stone surface is being reproduced. The apparatus according to the present invention for the printing of substrates made from a timber material or a synthetic material includes an engraved cylinder with indentations for receipt of printing ink and an off set printing roller, onto which the printing ink is transferred from the engraved cylinder and from which the ink is transferred onto the substrate. In one preferred embodiment, the printing roller has a hardness at its surface softer than 20 on the Shore A scale. The method according to the present invention for printing of substrates made from a timber material or a synthetic material comprises the following steps: application of printing ink to the indentations of an engraved cylinder, transfer of the printing ink from the engraved cylinder to an off-set printing roller, the surface of which has a hardness softer than 20 Shore A scale, and printing of the printing ink from the off-set printing roller onto the substrate. According to one preferred embodiment of the inventive apparatus, the¹ application of the printing ink onto the substrate takes place with a single engraved cylinder and a single printing roller. By so doing, the appearance of a natural wooden surface or a smooth stone surface, such as for example granite, can be achieved in an aesthetically pleasing manner. By the interplay between the form of the indentations in the engraved cylinder and the locally applied printing ink, the desired effects are able to be achieved with a relatively soft printing roller without the employment of multiple printing inks and printing rollers. In this way, for example, a natural appearing timber grain can be produced in a single printing step. The substrate materials employed may be of many different types, for example genuine timber, but preferably cheaper substitute materials are utilized, like for example medium-density fiberboard (MDF). Also, synthetic material such as ABS and PVC come into consideration for the substrate. The substrates printed and varnished according to the invention are for example particularly applicable as floorings and skirting boards, or also for external applications, i.e. for surfaces exposed to weathering, like for example window frames, fencing boards, etc. The invention is able to achieve the desired surface effect with a single engraved cylinder, it being the engraving cylinder which determines the surface configuration of the printed substrate. The use of a printing roller with a soft silicon layer has the advantage that no so-called "memory effect" develops in the surface of the printing roller, and in particular lightly textured (profiled) surfaces which are not completely smooth can be printed well. In particular, with the inventive printing technique, unbroken printed finishes can be achieved and the problem of a missing or discontinuous grain patterns occurring in the prior art can be avoided. The inventive use of the soft silicon roller also makes good printing possible in the region of indentations, edges and bevels. According to a preferred embodiment of the invention, a lacquer-application roller is located downstream of the silicon printing roller in the travel path of the substrate, wherein the lacquer-application roller preferably also includes a soft silicon outer surface. According to a further preferred embodiment of the invention, a pore-printing roller is located downstream of the lacquer-application roller in the travel path of the substrate for the imprinting of pores or grooves to provide the appearance of a wood grain or stone texture. This pore-printing roller is preferably also a roller with a soft silicon outer surface, which functions as an off-set printing roller and thereby applies a further layer of lacquer with indentions therein, whereby the indentions represent the surface texture of naturally occurring materials. Brief Description of the Drawings Figure 1 illustrates schematically a first application station in which printing ink is applied to a substrate. Figure 2 illustrates a second application station at which a lacquer coating is applied to the printed substrate. Figure 3 illustrates a third application station at which a layer of lacquer with pores is applied to the printed and lacquered substrate. Figure 4 illustrates a cross-section through a printing roller. Figure 5 illustrates a cross-section through a further example of a printing roller. Detailed Description of Invention In Figures 1, 2 and 3 a substrate 10 is conveyed from left to right sequentially through each of the stations illustrated in Figures 1, 2, and 3. The substrate 10 is for example a sheet made from a timber material or a synthetic material such as ABS or PVC. The advancement of the substrate 10 takes place with a conveyer belt 12, which is driven with rollers 14. The transport direction corresponds do the direction of rotation indicated with arrows. Prior to the first application station according to Figure 1 in the travel path of the substrate (i.e. left of Figure 1), a base lacquer, which may for example be lightly tinted, can he applied onto the substrate, in particular via spraying or rolling or other conventional application methods. The base lacquer may be a conventional acrylate borne, water borne, or solvent borne varnish. Metallic lacquers also come into consideration as possible base lacquers. The thickness of the base lacquer will vary depending on how dark or light it is desired for the lacquer layer to appear and will typically be between 2 and 130 um and more commonly between 30 and 50 um. This preparation of the substrate prior to its advancement to the first application station according to Figure 1 is a conventional process and is not shown in the drawings. The application station according to Figure 1 includes an offset printing roller 16, which in cross-section is represented for example in Figures 4 and 5. Printing roller 16 is "offset" in the sense that it is imprinted with the "negative" image of the pattern which appears on engraved cylinder 18 and will ultimately appear on substrate 10. The off-set printing roller 16 has a layer of soft silicon constituting its outer surface 20. The off-set printing roller 16 operates in conjunction with an engraved cylinder 18. In the outer surface of the engraved cylinder 18, indentations which correspond to the printed image to be generated on the substrate 10 are formed, i.e. for example indentations corresponding to a natural timber grain or also corresponding to a natural stone pattern, such as marble or granite. During reproduction of for example a timber grain, the degree of the indentation may correspond to the timber grain to the effect that the deeper the recess in the outer surface of the engraved cylinder, the darker should be the corresponding position in the grain image of the timber. Additionally, indentions of different depths on engraved cylinder 10 will help create the impression of a natural texture in the grain image. The rotational directions of the engraved cylinder 18 and the printing roller 16 are indicated with arrows. Conventional doctor blade arrangements 22, 24 maintain the outer surfaces of the cylinder and the roller clean, so that the printing ink only appears at and is evenly spread across the desired places. In a preferred embodiment, ink is applied in an amount of 10-30 grams wet ink per square meter of substrate. However, greater or lesser amounts of ink could be applied depending on the particular application. The substrate 10 moves in the rotational direction of the offset printing roller 16 at the same speed therewith so that the print image from the outer surface 20 of the printing roller 16 is transferred onto the substrate 10. Typically, printing roller 16 will apply a pressure of approximately 5 kg/cm² to the substrate 10, although higher pressures may be needed for substrates such as aluminum or steel. A second application station according to Figure 2 with a lacquer-application roller 26 and a lacquer-dosing roller 28 is positioned in the travel path of the substrate 10. A lacquer 32 is thereby applied onto the printed surface 30 of the substrate 10. The lacquer 32 will be of a similar type and layer thickness as the base lacquer layer described above. The rotational directions of the rollers are once again specified with arrows. The rollers are again impinged upon by conventional doctor blade arrangements 34, 36. The lacquer application roller 26 is also a silicon roller with soft outer surface having properties similar to off-set printing roller 16. The substrate 10 printed in the first application station according to Figure 1 and lacquered in the second application station according to Figure 2 is advanced with the conveyer belt 36 to a third application station according to Figure 3. There a further layer of lacquer is applied to the printed and lacquered outer surface 40 of the substrate 10 by means of a conveyer belt 42, which is driven via rollers 44, and a pore-printing roller 46 which operates in injunction with an engraved cylinder 48. The rotational directions of the rotating components are again marked with arrows and the thickness of the lacquer layer is similar to those described above. In the third application station according to Figure 3, an engraved cylinder 48 is installed which carries projections that correspond to the pores to be finally printed upon the substrate 10. The pore printing roller 46 is thereby provided with a layer of lacquer, which includes the desired small pores, the distribution of which exactly corresponds to the desired pore or grain pattern image of the timber surface to be reproduced. The pore printing roller again has a soft silicon outer surface similar to that of off-set printing roller 16. Conventional doctor blade arrangements 50, 52 operate in conjunction with the rollers in the same manner as previously described doctor blade aπangements 22, 24. The arrangement of the application stations according to Figures 1 and 3 in the specified operation sequence makes it possible to adapt the pores printed with the pore printing roller 46 to the grain printed with the printing roller 16, In the event that a timber image should be generated. In so doing, a grain or pore pattern which is "genuine" to the look and feel is created. Figures 4 and 5 show embodiment examples of printing milers, wherein the printing rollers according to these Figures may be correspondingly employed for the off-set printing roller 16 according to Figure 1 and/or the lacquer-application roller 26 according to Figure 2 and or the pore-printing roller 46 according to Figure 3. With the embodiment example in Figure 4, the roller 60 has a relatively thick silicon layer 62 of for example a thickness in the region of about 15 to 20 mm. The Shore hardness of this silicon layer is in the region of 10 to 50 Shore A scale, preferably in the region of 20 Shore A scale and softer. A so-called "memory effect" in the material is thereby completely avoided, i.e. after each print run the silicon layer again completely attains its smooth original shape. In particular, the soft silicon outer surface makes possible a printing of textured surfaces, i.e. formed with tight relief, with raised portions and indentations, such as is desired with for example the reproduction of timber surfaces. Also with stone surfaces, such as marble, granite or the like, a lightly textured surface may be desired to obtain an effect consistent with the natural surface feel. The roller 64 according to Figure 5 has an outer silicon layer 66 and an inner rubber layer 68, wherein the rubber layer 68 is somewhat harder than the outer soft silicon layer 66. With regard to the softness of the silicon layer 66, the specifications for the silicon layer 62 in Figure 4 apply. The rubber layer 68 may for example have a Shore A scale hardness of 40 or greater and a thickness in the region of about 12 mm to 76 mm depending on the geometry of the substrate material.

Claims

1. Apparatus for printing of substrates made from timber material or synthetic material, comprising: a. an engraved cylinder with indentations for the receipt of printing ink; b. an off-set printing roller, onto which the printing ink from the engraved cylinder is transferred and from which said ink is transferred onto the substrate; and c. wherein the printing roller has a hardness at its outer surface softer than 20 Shore scale A.

2. Apparatus according to claim 1, further comprising a single engraved cylinder and a single printing roller for the application of ink onto the substrate.

3. Apparatus according to one of the claims 1 or 2, wherein an application roller follows the printing roller for the application of lacquer onto the printed substrate.

4. Apparatus according to claim 3, wherein the application roller has a hardness softer than 20 Shore at its outer surface.

5. Apparatus according to one of the preceding claims, wherein a pore-printing roller follows the lacquer-application roller for the printing of pores on the substrate.

6. . Apparatus according to claim 5, wherein the pore-printing roller has a hardness softer than Shore scale A at its outer surface.

7. Apparatus according to one of the preceding claims, wherein the printing roller and/or the lacquer-application roller and/or the pore-printing roller has/have an outer surface formed from silicon.

8. Apparatus according to claim 5, wherein said pore printing roller and said off-set printing roller receiving ink have substantially the same texture pattern formed thereon.

9. Apparatus according to claim 1, wherein said engraved cylinder has indentions of differing depths.

10. Method for printing of substrates made from timber material or synthetic material comprising the steps of: a. applying printing ink in indentations of an engraved cylinder; b. transferring the printing ink from the engraved cylinder to an off-set printing roller having an outer surface of which has a hardness less than 20 Shore scale A; and c. printing the ink from the off-set printing roller onto the substrate.

11. Method according to claim 8, wherein the printing of the substrate with printing ink occurs with a single engraved cylinder and a single printing roller.

12. Method according to one of the claims 8 or 9, wherein a lacquer is applied onto the printed substrate by means of a lacquer-application roller.

13. Method according to one of the claims 8 or 9, characterized in that a lacquer-layer with pores is applied onto the printed and lacquered substrate by means of a pore-printing roller in the off-set process.