Method and apparatus for embossing a pattern on a substrate coated with a varnish

Abstract

A method and an apparatus for embossing a pattern into a varnish on a sheet-like substrate are provided. The method applies a planar stamp using a roller, while the apparatus includes a roller having a planar stamp.

Claims

1. A method for embossing a pattern on a substrate, comprising the steps of: coating a substrate with a varnish; applying a planar stamp onto the varnish on the substrate by lowering the planar stamp, which is fixed at one side of the substrate, into contact with the varnish on the substrate at an application rate in an application direction towards another side of the substrate by advancing a roller in the application direction at an advance rate, with a peripheral direction at the planar stamp opposite the application direction, and actively driving a peripheral speed of the roller in the application direction, whereby the planar stamp embosses a pattern into the substrate with the peripheral speed being lower than the application rate to compensate for elongation of the planar stamp; curing the varnish by light or thermally until the pattern is dimensionally stable; and pulling off the planar stamp.

2. The method of claim 1, further comprising pulling the planar stamp off in a direction opposite to the application direction.

3. The method of claim 1, wherein the planar stamp corresponds at least to a size of a surface area of the substrate coated with the varnish or to be patterned.

4. The method of claim 1, wherein the step of applying the planar stamp onto the substrate comprises setting an angle between a stamp surface not yet applied and the substrate to more than 45°.

5. The method of claim 1, wherein the step of applying the planar stamp onto the substrate comprises setting an angle between a stamp surface not yet applied and the substrate to more than 80°.

6. The method of claim 1, wherein the step of applying the planar stamp onto the substrate comprises applying the planar stamp at an application rate of more than 5 mm/s.

7. The method of claim 1, wherein the step of applying the planar stamp onto the substrate comprises applying the planar stamp at an application rate of more than 50 mm/s.

8. The method of claim 1, further comprising driving a lamp so as to follow the roller, wherein curing step comprises activating the lamp to cure the varnish.

9. The method of claim 1, further comprising resting the planar stamp on the substrate for a period of at least 2 seconds after the application step.

10. The method of claim 1, wherein the step of coating the substrate with the varnish comprises coating with the varnish, in a non-cured condition, having a viscosity of more than 500 mPa.Math.s.

11. The method of claim 1, wherein the step of coating the substrate with the varnish comprises coating with the varnish, in a non-cured condition, having a viscosity of between 800 and 1100 mPa.Math.s.

12. A method for embossing a pattern on a substrate, comprising the steps of: coating a substrate with a varnish; applying a planar stamp onto the varnish on the substrate by lowering the planar stamp, which is fixed at one side of the substrate, into contact with varnish on the substrate at an application rate in an application direction towards another side of the substrate by advancing a roller in the application direction at an advance rate and with a peripheral direction at the planar stamp opposite the application direction; driving the roller at a peripheral speed in the application direction that is lower than the application rate of the planar stamp to compensate for elongation of the planar stamp; curing, through the planar stamp, the varnish until the pattern is dimensionally stable; and pulling off the planar stamp.

13. A method for embossing a pattern on a substrate, comprising the steps of: coating a substrate with a varnish; lowering a stamp, which is fixed at one side of the substrate, into contact with the varnish on the substrate towards another side of the substrate at an application rate by advancing a roller at an advance rate in an application direction and with a peripheral direction at the planar stamp opposite the application direction; compensating for elongation of the stamp by driving the roller at a peripheral speed in the application direction that is lower than the application rate; and curing the varnish until the pattern is dimensionally stable.

14. The method of claim 13, wherein the step of curing the varnish until the pattern is dimensionally stable comprises curing through the stamp.

15. The method of claim 14, further comprising pulling off the stamp after the pattern is dimensionally stable.

16. The method of claim 13, further comprising pulling off the stamp after the pattern is dimensionally stable.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 schematically illustrates a side view of an apparatus for embossing a pattern;

(2) FIG. 2 is a perspective view of one of the two levers on which a roller is mounted; and

(3) FIG. 3 is a perspective view of a roller with gears.

DETAILED DESCRIPTION

(4) The subject matter of the invention will now be described by way of the drawings of FIGS. 1 to 3 with reference to an exemplary embodiment schematically illustrated therein.

(5) FIG. 1 schematically illustrates a side view of an apparatus 1 for embossing a pattern.

(6) The apparatus comprises a table 2 which is configured to be displaceable and can be moved into the apparatus from the right in this view. Means for displacing a table are known to persons skilled in the art and are not illustrated.

(7) A substrate 3, in particular in the form of a glass or glass ceramic sheet, rests on table 2 and is coated with a varnish (not shown).

(8) For embossing a pattern, apparatus 1 comprises a planar, i.e. sheet-like stamp 4.

(9) This view illustrates the position of stamp 4 at the start of the embossing operation.

(10) Stamp 4 is fixed at one end by means of a stamp holder 12 as a stamp fixture. It may for instance be clamped or may have recesses into which engaging members of the stamp holder (not shown) engage.

(11) During the embossing process, table 2 is locally fixed in the apparatus. Thus, stamp 4 is fixed at one end relative to substrate 3 by means of stamp holder 12.

(12) The apparatus further comprises a roller 5 by means of which the stamp 4 may be applied onto the substrate 3.

(13) For application of the entire surface of the sheet, a stamp holder 8 is provided which in this embodiment is equipped with a spring that allows for a movement of the stamp holder 8 in vertical direction.

(14) During an embossing operation, roller 5 is advanced to the right, in the horizontal direction, by a drive 6 at an advance rate.

(15) Stamp holder 8 is also moved to the right, in a manner so that the angle between the stamp surface area not yet applied and the substrate 3 remains constant during the application process.

(16) Arrow 9 symbolizes the movement direction of the advancing roller to the right.

(17) As the stamp is applied, stamp holder 8 is moved vertically downwards, in a movement direction symbolized by arrow 10.

(18) The movement of the upper edge of stamp 4 resulting therefrom is symbolized by arrow 11, running in a straight line towards a right edge of substrate 3.

(19) Roller 5 can be lifted by means of a lifting mechanism 14.

(20) A UV lamp which follows the movement of the roller is not illustrated in this view.

(21) Preferably, the varnish applied on substrate 3 is cured through stamp 4 once the stamp 4 has been applied.

(22) Then, roller 5 is lifted by lifting mechanism 14 not shown in more detail here, and the stamp is lifted substantially in the opposite movement direction, i.e. opposite to arrow 11.

(23) Then, substrate 3 may be retracted from the apparatus by means of table 2 and may be subjected to further processing steps.

(24) Roller 5 is mounted on pivotable levers 7 which are connected to the apparatus or lifting mechanism 14 via a vibration damper 15.

(25) Furthermore, the roller is driven by an active drive 13. The peripheral speed of roller 5 is adjustable by drive 13, in particular such that the peripheral speed might be slightly less than the application rate when applying the stamp 4.

(26) Stamp 4 should be applied in a manner so that the angle of the not yet applied portion of stamp 4 (except for the portion that directly engages the roller) and the substrate 3 is more than 45°, preferably more than 75°.

(27) Preferably, the roller has a diameter between 3 and 50 cm.

(28) Details of the roller mechanism will now be explained with reference to FIG. 2 and FIG. 3 which are perspective views of components of the apparatus.

(29) FIG. 2 illustrates one of the two levers 7 on which the roller is mounted.

(30) It shows the shaft 16 of the roller and gears 17 and 18 through which the roller is actively driven.

(31) Moreover, a belt 19 can be seen, which serves to drive gear 18 by which the roller is driven through gear 17.

(32) It goes without saying that the drive mechanism illustrated herein may as well be configured in any other manner.

(33) Levers 7 are pivotally arranged on a bearing 21 so that roller 5 can be raised to be relieved when the stamp is lifted.

(34) FIG. 3 shows roller 5 with gears 17.

(35) Shaft 16 of roller 5 is mounted in ball bearings 20 which are inserted into the levers (7 in FIG. 2).

(36) The invention permits patterning of highly viscous varnishes with high pattern fidelity, reduced number of defects, and high processing speed.

(37) TABLE-US-00001 LIST OF REFERENCE NUMERALS 1 Apparatus for embossing a pattern 2 Table 3 Substrate 4 Stamp 5 Roller 6 Drive 7 Lever 8 Stamp holder 9 Movement direction of advancing roller 10 Movement direction of stamp holder 11 Movement of stamp upper edge 12 Stamp holder 13 Active drive 14 Lifting mechanism 15 Vibration damper 16 Shaft 17 Gear 18 Gear 19 Belt 20 Ball bearing 21 Bearing