JP2003211072A - Method for controlling coating weight profile - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for controlling a coating weight profile capable of manufacturing coated paper which is uniform in the thickness profile of coated paper after coating, is decreased in finishing defects in particular and is good in printing operability. <P>SOLUTION: The method for controlling the coating weight profile in a coated paper manufacturing process step including a paper machine process step and a coating process step comprises setting a moisture content profile measured in the paper machine process step as a reference profile, forming a target profile of the coating weight from the reference profile and controlling the coating weight profile in such a manner that the target profile is attained. <P>COPYRIGHT: (C)2003,JPO

Description

Description: BACKGROUND OF THE INVENTION [0001] 1. Field of the Invention [0002] The present invention relates to a method for controlling a coating amount profile, and more particularly, to a method for controlling a coating amount profile, in which a coated paper has a uniform thickness profile and finish defects. The present invention relates to a coating amount profile control method capable of producing coated paper with a small amount of printing operability. [0002] A conventional coating amount profile control method is as follows.
In the coating process, the coating amount profile after coating is measured, and the coating amount profile is idealized by feedback control to the coating amount profile adjuster.
For example, the control is performed so that the coating amount has a uniform coating amount profile in the width direction. [0003] Among the characteristic profiles of the coated paper web, those that particularly affect the quality include the thickness profile of the coated paper web. [0004] If the thickness profile of the paper web after coating is not uniform, swelling may occur during winding after coating at a portion where the thickness of the paper web is large. The blisters cause the formation of wrinkles and wrinkles during the finishing process and printing. If the thickness profile of the coated paper web is not uniform, when the paper web is subjected to the super calendar process, the crushing of the paper web in the width direction becomes non-uniform. It has an adverse effect on the quality such as gloss. Also,
It may cause uneven wear of the calendar roll. For the reasons described above, it is desirable that the thickness profile of the coated paper web is uniform. Although the thickness profile of the paper web after coating is affected by the characteristic profile of the paper web before coating, the above-described coating amount profile control method does not consider the effect, and the effect is not considered. It is difficult to make the thickness profile of the paper web uniform. Further, in order to make the thickness profile of the coated paper web uniform, the thickness profile of the coated paper web is measured and fed back to the coating amount profile controller to obtain the coating amount. It is conceivable to control the thickness profile of the paper web after coating by adjusting the increase or decrease of
When measuring the thickness profile of the paper web after coating,
If a contact-type thickness sensor is used, the surface of the coated paper web will be damaged. Therefore, a contact-type thickness sensor cannot be used. Further, it is difficult to accurately measure the thickness of the non-contact type thickness sensor because of the flapping of the paper web, and it is difficult to control the thickness profile after coating using feedback control. [0008] In view of these drawbacks, the present invention has a uniform thickness profile of coated paper after coating, has particularly few finish defects, and has good printing operability. It is an object of the present invention to provide a coating amount profile control method capable of producing a coated paper with a high quality. A method of controlling a coating amount profile according to the present invention is a method of controlling a coating amount profile in a coated paper manufacturing process including a paper making process and a coating process. The obtained moisture profile is used as a reference profile, a target profile of the coating amount is created from the reference profile, and the coating amount profile is controlled so as to become the target profile. Hereinafter, the contents of one embodiment of the present invention will be described in detail with reference to the drawings. FIG. 1 is a schematic diagram of a paper making process in a coated paper manufacturing process. In the paper making process in FIG. 1, a stock is supplied from a head box 1 and the stock is supplied to a wire part 2.
The paper web 11 is dehydrated in the press part 3 and dried in the pre-dryer 4 to form the paper web 11.
Is coated with a sizing agent by a size press 5, dried by an after dryer 6, passed through a calendar 7, and wound up by a reeler 8. Between the pre-dryer 4 and the size press 5 and between the calendar 7 and the reeler 8, profile measuring devices 9a and 9 for measuring the characteristic profile of the paper web 11 are provided.
b is installed. The profile measuring devices 9a and 9b
At least a basis weight profile and a moisture profile are measured. The head box 1 is provided with a grammage profile control device 10, which is based on the absolute dry grammage profile calculated from the grammage profile measured by the profile measuring device 9a and the moisture profile. Is controlled so that is flat. FIG. 2 is a schematic view of a coating process in a coated paper manufacturing process. In the coating process in FIG. 2, the paper web 18 wound by the reeler 8 in the papermaking process in FIG. 1 is unrolled by the unreeler 12, a coating liquid is applied by the coater unit 13, dried by the dryer 14, and Rolled up. A paper web 18 is provided between the unreeler 12 and the coater section 13 and between the dryer 14 and the reeler 15.
Measuring device 16 for measuring the characteristic profile of
a and 16b are installed. The profile measuring device 16
a and 16b measure at least the basis weight profile and the moisture profile. The coater section 13 is provided with a coating amount profile controller 17 which is configured to calculate a coating amount calculated from the basis weight profile and the moisture profile measured by the profile measuring devices 16a and 16b. Control is performed so that the work amount profile becomes the set application amount profile. There is a correlation between the moisture profile of the paper web produced in the papermaking process and the thickness profile before calendering in the papermaking process. In addition, when the thickness profile is adjusted by the calendar in the papermaking process, in any case where the adjustment is not performed, the coating liquid is applied to the paper web in the coating process and the fibers of the paper web are rewet. The thickness profile after coating has a correlation with the thickness profile before calendering in the papermaking process. The coating amount profile control method according to the present invention comprises:
Utilizing the relationship between the moisture profile and the thickness profile described above, the moisture profile of the paper web in the papermaking process is fed forward to the coating amount profile controller in the coating process, and the thickness profile of the paper web after the coating is applied. Is a method of controlling a coating amount profile. FIG. 3 is a schematic diagram of the coating amount profile control method of the present invention. The moisture profile measured by the profile measuring device 9a installed in the paper making process is stored in the profile storage device every time the measurement is performed. In the target profile creation step, a moisture profile measured within an arbitrary time set in advance is acquired from the profile storage device, an average of the acquired moisture profiles is calculated, and a moisture average value in the width direction is subtracted to obtain a reference value. Create a profile. Further, a target profile is created by multiplying the created reference profile by a coefficient having a preset negative value. The coefficient is desirably determined on the basis of the ratio of the amount of water to the thickness of the paper web and the ratio of the amount of coating to the thickness of the coating layer. The created target profile is transmitted to the coating amount profile control device 17 in the coating process, and the coating amount profile control device 17 performs control so as to become the target profile. In the present invention, the paper making process and the coating process do not need to be divided, and a coated paper manufacturing apparatus generally called an on-machine coater in which the paper making process and the coating process are continuously performed, The coating amount profile control method of the present invention is applicable. In the present invention, the coating step of applying the coating liquid to only one side of the paper web or the coating step of applying the coating liquid to both sides of the paper web, The coating amount profile control method is applicable. Embodiments of the present invention will be described below with reference to the drawings. Embodiment 1 FIG. 4 is a schematic view of an embodiment in which a coating amount profile control method according to the present invention is applied to a coated paper manufacturing apparatus including a paper machine and a coating machine. The paper machine has a head box 21, a wire part 22, a press part 23, a pre-dryer 24, a size press 25, an after-dryer 26, a calendar 27, and a reeler 28. A BM meter 2 is provided between the pre-dryer 24 and the size press 25 and between the calendar 27 and the reeler 28.
9a and 29b are installed, and the BM meters 29a and 29b are 3
The basis weight profile and moisture profile are measured every 0 seconds. The head box 24 is provided with a grammage profile control device (not shown). The grammage profile control device includes a grammage profile and a moisture profile measured by a BM meter 29a installed between the pre-dryer 24 and the size press 25. Is controlled so that the absolute dry basis weight profile calculated from the above becomes flat. A computer 41 is connected to the BM meter 29a installed between the pre-dryer 24 and the size press 25 by a communication cable 42a, and the computer 41 stores the moisture profile measured by the BM meter 29a in a storage device inside the computer 41. save. The computer 41 can receive the reel changeover signal, order number and reel number by a method not shown. The computer 41 reads the moisture profile measured by the BM meter 29a from the storage device inside the computer 41 during the period from the previous frame change to the current frame change at the time of the frame change, and calculates the average profile of the read moisture profiles. Calculation is performed to obtain a moisture profile of one frame average, and furthermore, a moisture average value in the width direction of the moisture profile of one frame average is reduced to obtain a reference profile, and a coefficient previously stored in a storage device inside the computer 41 in the reference profile. Is multiplied as a target profile, and the target profile is stored in a storage device inside the computer 41 by linking the order number and the reel number. The coating machine includes an unreeler 32, a coater unit 3
3, a dryer 34 and a reeler 35. Between the unreeler 32 and the coater 33 and between the dryer 34 and the reeler 35, the BM meters 36a, 3
6b is installed, and the BM meters 36a and 36b measure the basis weight profile and the moisture profile every 30 seconds. A coating amount profile control device (not shown) is installed in the coater section. The coating amount profile control device includes a BM meter 3 installed between the dryer 34 and the reeler 35.
6b before the coating calculated from the absolute dry basis weight calculated from the basis weight profile and the moisture profile measured from the measured basis weight profile and the moisture profile measured by the BM meter 36a installed between the unreeler 32 and the coater 33. The coating amount profile obtained by reducing the absolute dry basis weight is controlled to be the target profile. The method of setting the target profile will be described below. The coating amount profile control device is
The computer 41 connected to the M meter 29a is connected by a communication cable 42b. Immediately before coating a paper web frame formed by a paper machine, the coating amount profile control device specifies an order number and a reel number, and sets a corresponding target profile to the computer 4.
1. The application amount profile is extracted from the internal storage device, and the coating amount profile is controlled so as to become the target profile. As described above, according to the coating amount profile control method of the present invention, the thickness profile of the coated paper after the coating is uniform, the finish defect is particularly small, and the printing is further performed. It is possible to produce coated paper having good operability.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic diagram of a paper making process in a coated paper manufacturing process. FIG. 2 is a schematic view of a coating process in a coated paper manufacturing process. FIG. 3 is a schematic diagram of a coating amount profile control method of the present invention. FIG. 4 is a schematic diagram of a coated paper manufacturing apparatus including a paper machine and a coating machine to which a coating amount profile control method according to the present invention is applied. [Description of Signs] 1, 21 Head Box 2, 22 Wire Part 3, 23 Press Part 4, 24 Pre-Drier 5, 25 Size Press 6, 26 After Dryer 7, 27 Calendar 8, 28, 15, 35 Reelers 9a, 9b, 16a, 16b Profile measuring device 10 Basis weight profile control device 11, 18 Paper web 12, 32 Unreeler 13, 33 Coater section 14, 34 Dryer 17 Coating amount profile control device 29a, 29b, 36a, 36b BM meter 41 Computer 42a, 42b communication cable

Claims (1)

Claims: 1. A method for controlling a coating amount profile in a coated paper manufacturing process including a papermaking process and a coating process, wherein a moisture profile measured in the papermaking process is used as a reference profile, and A coating amount profile control method comprising: creating a target coating amount profile; and controlling the coating amount profile so as to achieve the target profile.