Method and apparatus for making patterned paper

Abstract: A method and apparatus for making patterned paper. A printer (10, 10') patterning the paper is arranged in a patterning unit (4) arranged in a paper machine (1), the printer (10, 10') patterning a paper web (3) being made in the paper machine (1). The printer (10, 10') is preferably an ink-jet printer. The paper web (3) patterned by the patterning unit (4) can be coated by a coating unit (5) arranged in the paper machine (1).

Description: The invention relates to a method for making patterned paper, in which method the paper is made in a paper machine and patterned (see US-A-4 504 357). The invention further relates to an apparatus for making patterned paper, which apparatus comprises a paper machine and a patterning means for paper. Some paper grades are patterned with various patterns before the paper is delivered to its user. The patterns may be used for aesthetic purposes, for communicating necessary information - in the packaging, for instance - or for some other purpose. In this application, patterning refers to both text and images. In prior art, paper is patterned in a separate work phase. For instance, patterned baking paper is made by first making the paper in a paper machine, and then transferring the paper to a separate patterning unit in which patterning is typically done by printing. In a third phase, the paper is siliconized, i.e. coated with silicone which gives the paper the good detaching properties typical of baking paper. Patterning must be done prior to siliconizing so as to have the colour stick permanently to the paper. The manufacturing process thus comprises three phases which are all done with different machines and possibly in different factories or even in different localities, and between the phases, the paper reels need to be moved and stored. The manufacturing process in its entirety is, therefore, expensive and complex as it is time-consuming and requires several different machines and work phases. In addition, changing the patterns for the paper is time-consuming, and consequently, the patterning of small batches of paper with special patterns, for instance, is not economically profitable. It is an object of the present invention to provide a method and an apparatus for making patterned paper, in which the above-mentioned drawbacks do not exist. The method of the invention is characterized in that a patterning unit is arranged in a paper machine, and a printer belonging to said patterning unit patterns the paper web being made in said paper machine, and that the paper web is made into a baking paper which is siliconized. An apparatus of the invention is characterized in that the patterning means comprises a printer arranged to the patterning unit arranged in the paper machine, and that the printer is arranged to pattern the paper web being made in said paper machine. The essential idea of the invention is that a patterning unit is arranged in a paper machine making the paper to be patterned, and the patterning unit patterns desired patterns in to the paper web running in the paper machine. Further, the idea of a preferred embodiment is that the patterning unit comprises one or more printers, whereby the rate of patterning or complexity of patterns can be increased. The idea of another preferred embodiment is that the printer is preferably an ink-jet printer which comprises one or more printing heads, thus making the patterning especially easy. The idea of a third preferred embodiment is that a coating unit is arranged in the paper machine after the patterning unit in the direction of travel of the paper web, and the already patterned paper web is coated at the same time with making and patterning it. The idea of a fourth preferred embodiment is that the patterned and coated paper is a siliconized baking paper. The invention provides the advantage that paper patterning is performed at the same time and in the same apparatus as paper making, whereby making patterned paper becomes fast. The paper need not be transferred away from the paper machine for patterning, thus avoiding transporting, storing and other extra intermediate phases, which reduces considerably the manufacturing costs and lead-time of patterned paper. Even complex patterns can easily and simply be patterned on the paper, and the patterns can be changed and altered even during patterning through a control program of the patterning unit. Further, a preferred embodiment provides the advantage that by coating the patterned paper immediately after the patterning by means of a coating unit arranged in the paper machine, it is possible to further reduce transport and storage costs and speed up the manufacturing process. In addition, by immediate coating, the patterns are right away covered under the coating and cannot wear or otherwise deteriorate before delivery to the customer. The invention will be described in greater detail by means of the attached drawings in which Figure 1 is a greatly simplified schematic of an embodiment of the apparatus of the invention from the side, Figure 2 is a schematic of the embodiment of the invention shown in Figure 1 from the top, and Figure 3 is a schematic of a second embodiment of the apparatus of the invention from the top. Figure 1 is a greatly simplified schematic of an embodiment of the apparatus of the invention from the side. A paper machine 1 making paper to be patterned is shown by a dashed line in the figure. The paper machine 1 is known per se to a person skilled in the art and consequently, it is not described in detail herein. Further, the operation of the paper machine 1 is known per se to a person skilled in the art and, therefore, need not be described in detail herein. The paper machine 1 comprises means for forming and drying a paper web, in other words, a forward end, a press section and a dryer section, which means are marked by reference number 2 in Figure 1. The paper web 3, whose direction of travel is shown with an arrow in Figure 1, coming from the forming and drying means 2, is led to a patterning unit 4. The patterning unit 4 comprises a printer 10 whose printing head 11 prints the desired patterns onto the paper web 3. The printer 10 may comprise one or more printing heads 11 whose imprints may also be of various colours. Said patterns may comprise graphical patterns, writing, combinations thereof or other corresponding patterns. The patterns typically repeat as such on the paper web 3 at certain intervals, but they may also be randomly located or change continuously. The patterning unit 4 is controlled by a control unit 12 which comprises at least a program for controlling the printing heads 11 of the printer 10 and a user interface. With the control unit 12, it is possible to control the patterning unit 4 in real time so that the patterns can be quickly changed into other patterns. This way, it is possible to pattern even quite small paper batches while the manufacturing costs remain low. In the embodiment shown in Figure 1, there is a patterning unit 4 arranged both above and below the paper web 3 opposite each other. This way, the paper web 3 can be patterned on both sides with the desired patterns. The patterning units 4 arranged on both sides of the paper web 3 can also reside in different locations in relation to each other in the direction of travel of the paper web 3. In a second embodiment of the invention, the patterning unit 4 is arranged on one side of the paper web 3 only so as to pattern the web 3 on that side only. In the embodiment shown in Figure 1, the patterning unit 4 is arranged after the dryer section of the paper machine 1. The patterning unit 4 can also be arranged in the paper machine 1 so that a part of the dryer section is after the patterning unit 4 in the direction of travel of the paper web 3. The printer 10 is preferably an ink-jet printer, by means of which it is easy and fast to make even complex patterns on the surface of the paper web 3. The structure and operation of an ink-jet printer is known per se and is, therefore, not described in more detail herein. The imprint of a printing head 11 of the applied ink-jet printer can be either one-colour or multicolour whereby multicolour patterns can be made on the paper web 3. In the embodiment shown in Figure 1, the patterned paper web 3 runs from the patterning unit 4 to a coating unit 5 arranged in the paper machine 1, and in the coating unit, the paper web 3 is coated with a coating layer 6 either on both sides, as shown in Figure 1, or on one side only. For instance, when making baking paper, the paper web 3 is today usually coated with a layer comprising silicone, i.e. the web is siliconized. Depending on the use of the paper, the coating layer 6 may also be of a material other than silicone. The coating 6 must always be at least to some extent transparent so as to allow the patterns made on the paper web 3 to show through it. The coated paper web 9 is led after the coating unit 5 on to means for further processing 7 which comprise a winder and reelers, for instance. The coated and patterned paper is thus made substantially entirely in the paper machine 1, making the manufacture extremely fast and simple. No separate machinery is required for patterning and coating the paper, and the paper need not be moved to another location for patterning or coating, which shortens the lead-time and reduces the need for production and storage space. If coated paper grades are not made in the paper machine 1, the coating unit 5 can naturally be left out of the paper machine 1. Figure 2 is a schematic of the embodiment of the invention shown in Figure 1 from the top. The reference numbers of Figures 1 and 2 correspond to each other. The paper web 3 formed in the forming and drying means 2 runs in the direction shown by the arrow into the patterning unit 4 arranged in the paper machine 1, where it is patterned by patterns 8 and 13. After this, the web runs on to the coating unit 5 arranged in the paper machine 1 for coating, and then the coated paper web 9 is led to the means for further processing 7 of the paper machine 1, where the coated paper web 9 is processed in a manner known per se before delivered to further processing. In the embodiment shown in Figure 2, the patterning unit 4 comprises four printers 10 placed side by side, each printer arranged to pattern a part of the width of the paper web 3 in such a manner that the entire width of the paper web can substantially be patterned. The number of printers 10 in the patterning unit 4 is naturally not limited to four, but it can be a larger or smaller number. Each printer 10 is controlled by a control unit 12, through which the printers 10 can all be made to make the same pattern 8 on the web 3, or alternatively one or more printers 10 can be made to make a pattern 13 differing from that of the other printers 10. Patterns 8, 13 can be continuously repeating, or continuously changing in a desired manner and differing from each other. By increasing the number of parallel printers 10, the part of the web 3 width each of them patterns becomes narrower and the length of movement of the printing heads 11 becomes smaller, whereby the speed of the paper web 3 being patterned can correspondingly be increased. The printing heads 11 are not shown in Figure 2 to simplify the figure. Figure 3 is a schematic of a second embodiment of the apparatus of the invention from the top. It should be noted that the reference numbering in Figure 3 corresponds to that of Figures 1 and 2. The paper web 3 is led as described in the above figures from the forming and drying means 2 to the patterning unit 4'. The patterning unit 4' comprises three printers 10' which are arranged consecutively in a series in the direction of travel of the paper web 3 and which all can be used to pattern substantially the entire width of the paper web 3. In other words, the printing heads 11 of each printer 10', which are not shown in Figure 3 to simplify the description of the matter, move substantially on the entire width of the paper web 3. The patterning of the paper web 3 is arranged so that each printer 10' patterns only a part of the desired pattern. In an embodiment, the printers 10' pattern the paper web 3 with imprints of different colours, which form the final multicolour patterning. In another embodiment, the imprints of each printer 10' are of the same colour, making the final patterning one-coloured. It is naturally possible to have more or less than three printers 10' arranged consecutively in the patterning unit 4'. The control unit 12 of the patterning unit 4' is arranged in the paper machine 1, preferably together with the control and monitoring units of the paper machine 1 known per se, whereby the process of making patterned paper can, in its entirety, be controlled and monitored from the same control room. The drawings and the description related to them is only intended to illustrate the idea of the invention. The invention may vary in detail within the scope of the claims. Thus, the patterning unit may comprise printers arranged both side by side and consecutively. In addition, the printers may be arranged suitably interlocked with each other. There may be more than one patterning unit arranged in the paper machine, which further speeds up the patterning of extremely complex patterns, for instance.

Claims: A method for making patterned paper, in which method the paper is made in a paper machine (1) and patterned, characterized in that a patterning unit (4) is arranged in the paper machine (1), a printer (10, 10') of which patterning unit (4) patterns the paper web (3) being made in said paper machine (1), and that the paper web (3) is made into baking paper which is then siliconized. A method as claimed in claim 1, characterized in that the patterning unit (4) comprises at least two printers (10, 10'). A method as claimed in claim 1 or 2, characterized in that at least two patterning units (4) are arranged in the paper machine (1). A method as claimed in any one of the preceding claims, characterized in that at least one printer (10, 10') is an ink-jet printer comprising one or more printing heads (11). A method as claimed in any one of the preceding claims, characterized in that the paper machine (1) comprises a coating unit (5), to which the paper web (3) patterned in the patterning unit (4) is led and in which the patterned paper web (3) is coated on at least one side with a coating layer (6). A method as claimed in any one of the preceding claims, characterized in that some of the printers (10, 10') pattern the top side of the paper web (3) and some of the printers (10, 10') the bottom side of the paper web (3). A method as claimed in any one of the preceding claims, characterized in that the patterning unit (4) patterns the paper web (3) with patterns (8, 13), which continuously repeat as such. A method as claimed in any one of claims 1 to 6, characterized in that the patterning unit (4) patterns varying patterns on the paper web (3). An apparatus for making patterned paper, which apparatus comprises a paper machine (1) and a patterning means for paper, characterized in that the patterning means is a printer (10, 10') arranged a patterning unit (4) arranged in the paper machine (1), that the printer (10, 10') is arranged to pattern a paper web (3) being made in said paper machine (1), and the paper machine (1) is arranged to make baking paper which is siliconized. An apparatus as claimed in claim 9, characterized in that the patterning unit (4) comprises at least two printers (10, 10'). An apparatus as claimed in claim 9 or 10, characterized in that at least two patterning units (4) are arranged in the paper machine (1). An apparatus as claimed in any one of claims 9 to 11, characterized in that at least one printer (10, 10') is an ink-jet printer comprising one or more printing heads (11). An apparatus as claimed in any one of claims 9 to 12, characterized in that the paper machine (1) comprises a coating unit (5) arranged after the patterning unit (4) in the direction of travel of the web (3), the coating unit being arranged to coat the already patterned paper web (3) on at least one side. An apparatus as claimed in any one of claims 9 to 13, characterized in that at least some of the printers (10, 10') of the patterning unit (4) are arranged side by side in the lateral direction of the paper web (3). An apparatus as claimed in any one of claims 9 to 14, characterized in that at least some of the printers (10, 10') of the patterning unit (4) are arranged consecutively in the direction of travel of the paper web (3). An apparatus as claimed in any one of claims 9 to 15, characterized in that the printing heads (11) of the printers (10, 10') are one-colour printing heads. An apparatus as claimed in any one of claims 9 to 15, characterized in that the printing heads (11) of the printers (10, 10') are multicolour printing heads. An apparatus as claimed in any one of claims 9 to 17, characterized in that some of the printers (10, 10') are arranged to pattern the topside of the paper web (3) and some of the printers (10, 10') are arranged to pattern the bottom side of the paper web (3). An apparatus as claimed in any one of claims 9 to 18, characterized in that the patterning unit (4) is arranged to pattern the paper web (3) with a pattern, which continuously repeats as such. An apparatus as claimed in any one of claims 9 to 18, characterized in that the patterning unit (4) is arranged to pattern the paper web (3) with patterns differing from each other.

Inventors: TALJA MARTTI, TALJA, MARTTI
Applicants: METSAE TISSUE OYJ
Application year: 2000
Main classification: D21F11
IPC codes: D21F11, D21H19, D21H27, B41J2