Paper making and fiber liberation – Processes and products – Non-uniform – irregular or configured web or sheet
Reexamination Certificate
2001-04-24
2002-09-24
Fortuna, Jose (Department: 1731)
Paper making and fiber liberation
Processes and products
Non-uniform, irregular or configured web or sheet
C162S112000, C162S113000
Reexamination Certificate
active
06454901
ABSTRACT:
TECHNICAL FIELD
This invention relates to a manufacturing process of crepe paper products and to a method of improving creping in the manufacturing process of crepe paper products in which a cylindrical Yankee dryer is used.
BACKGROUND ART
As the living standard improves in recent years, the demand for paper body provided with crepe such as facial tissue, bath tissue, etc. has risen.
This paper body P provided with crepe or crepe paper is manufactured by attaching a paper body (wet paper) to the surface of a heated Yankee dryer Y, drying the same for a certain period of time, and separating the paper body P from the cylindrical Yankee dryer Y through a doctor blade D (see FIG.
2
).
Incidentally, R represents a winding roll, R
1
a touch roll and R
2
an auxiliary roll.
To be more specific, the paper body P accumulates potential crepe forming power in the process of drying up while it is attached to the smoothed surface of the dryer, and when it is separated from the surface of the cylindrical Yankee dryer by the doctor blade D, it forms instantly curved crepes.
Now, the formation of a paper body P with a good creping requires the adhesiveness (close contact) of the paper body to a heated cylindrical Yankee dryer Y, and its extent affects seriously the form of crepe.
In other words, it is known that, if the adhesiveness of the paper body to the cylindrical Yankee dryer is strong, the paper body P having been separated from the surface by the doctor blade forms fine and minute crepes (or “microhold”) as shown in
FIG. 3
, and weak adhesiveness leads to the formation of course crepes (or “macroholds”).
In addition, the more microholds are, the longer will be the length of the paper body produced (when no tension is applied) (the lower will be the crepe ratio), and the more productivity improves.
On the other hand , the more macroholds are , the shorter will be the length of the paper body produced (when no tension is applied) (the higher will be the crepe ratio), and the lower productivity falls.
It should be noted here that adhesiveness is said to be correlative with the smoothness of the dryer surface.
On the other hand, even under the impact of separation from the surface of the cylindrical Yankee dryer by the action of the doctor blade, an over-adhesion phenomenon of the paper body not separating from the surface and passing under the doctor blade occurs.
As a result, the surface of the paper body is damaged or the surface of the cylindrical Yankee dryer is stained.
This is a phenomenon that occurs due to a poor releasability of the paper body from the surface of the cylindrical Yankee dryer.
And this phenomenon become noticeable as the doctor blade gets increasingly worn out, and paper body that has been produced tend often to have macroholds constituting a qualitative disadvantage.
Therefore, in the normal operation, the doctor blades are replaced four to eight times a day (every three to six hours) constituting an issue for improving productivity.
Thus, it is necessary to guarantee contradicting matters, specifically the adhesiveness of the paper body to the surface of the cylindrical Yankee dryer and the releasability of the paper body from the surface of the cylindrical Yankee dryer.
In the meanwhile, an effective means used lately to improve productivity of paper with crepe is mainly to increase the surface speed of the cylindrical Yankee dryer, in other words to increase as much as possible the diameter of the cylindrical Yankee dryer.
However, the cylindrical Yankee dryers are made of casting from the viewpoint of thermal conductivity and temperature changes on the surface, and the larger the diameter of the cylindrical Yankee dryer is (at present some of them has a diameter of six meters or more), their surface tend to become softer.
When they become soft, the action of the doctor blades in contact with them causes naturally their surface to be worn and lose smoothness, and the paper body becomes less adhesive to the cylindrical Yankee dryer.
For these reasons, at present an adhesive, or a adhesive and a release agent are applied on the cylindrical Yankee dryer to fill the unevenness of the dryer surface and to form a coating layer consisting of a adhesive and a release agent. (See e.g. Japanese Patent Application Laid Open 2000-127597)
Although this method is certainly effective, but the coating layer formed by an adhesive is scraped by the doctor blade, the surface of the coating layer itself becomes course and the resulting deterioration of adhesivenss is a disadvantage.
Also the disadvantage of pulverized paper and adhesive cannot be treated lightly.
The present invention is made with an intent of solving these various issues.
In other words, the present invention has an object of improving the adhesiveness of the paper body to the surface of cylindrical Yankee dryer in the manufacturing process of paper body in which a cylindrical Yankee dryer is used and to make a high- quality crepe form.
DISCLOSURE OF THE INVENTION
Thus the inventors of the present invention kept up their efforts to overcome these issues.
As a result, they found that the continuous application of a release agent, an adhesive and a crepe assistant including solid lubricants on the surface of the cylindrical Yankee dryer resulted to their surprise in the development of a lubricant action between the doctor blade and the cylindrical Yankee dryer, and as a result the wear and tear of a film (coating layer) formed on the cylindrical Yankee dryer can be reduced to the minimum and the adhesion of the paper body can be improved. Based on this finding, they completed the present invention.
Specifically, the present invention relates to (1) a manufacturing process of crepe paper products by attaching a paper body on the surface of a rotating cylindrical dryer, separating said paper body from said surface through the doctor blade, wherein a crepe assistant including a fixed amount of solid lubricant is fed directly to the surface of the cylindrical Yankee dryer while the paper body is fed to the cylindrical Yankee dryer.
And (2) the present invention relates to the manufacturing method of high-quality crepe paper products according to item (1) wherein the solid lubricant is a lamellar crystal type solid lubricant.
And (3) the present invention relates to the manufacturing method of high-quality crepe paper products wherein the lamellar crystal type solid lubricant is molybdenum disulfide.
And (4) the present invention relates to the manufacturing process of high-quality crepe paper products according to item (3) wherein the powder size of molybdenum disulfide is within a range of 0.1 &mgr;m~10 &mgr;m.
And (5) the present invention relates to the manufacturing method of high-quality crepe paper products according to item (3) wherein the amount of solid lubricant fed is within a range of 0.1 &mgr;g-&mgr;g/m
2
.
And (6) the present invention relates to a manufacturing method of high-quality crepe paper products wherein a paper body is attached to the surface of a rotating cylindrical Yankee dryer and then said paper body is separated from said surface through the doctor blade and a crepe assistant including molybdenum disulfide within a range of 0.1 &mgr;g-100 &mgr;g/m
2
directly on the surface of the cylindrical Yankee dryer when the paper body is fed to the cylindrical Yankee dryer.
And (7) the present invention relates to a manufacturing method of high-grade crepe paper products wherein a paper body is attached to the surface of a rotating cylindrical Yankee dryer and then said paper body is separated from said surface through the doctor blade and including the following steps 1) to 4):
1) The step of feeding a crepe assistant including a solid lubricant directly onto the surface of a rotating cylindrical Yankee dryer while the cylindrical Yankee dryer is operated to supply paper, the step of “supply chemicals”;
2) The step of forming film by feeding a crepe assistant including a solid lubricant and filling fine unevenness on the surface of the cylindrical Yankee dryer, the step of “forming a film”;
Sekiya Hiroshi
Sekiya Kunio
Fortuna Jose
Maintech Co., Ltd.
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