JPH03181371A - Method for washing backing roll of one side coating machine - Google Patents

Abstract

PURPOSE:To obviate the generation of the abnormal phenomenon, such as scum rotating, of a backing roll by pouring a washing liquid contg. pigments of 0.05 to 30wt.% as solid content concn. to a doctor part for washing the backing roll of a one side coating machine. CONSTITUTION:The aq. washing liquid is prepd. by compounding and mixing the pigments of 0.05 to 30wt.% solid content concn. The above-mentioned aq. washing liquid is poured to the doctor part 5 for washing of the backing roll 2 in the one side coating machine to wash the backing roll 2. The more specific examples of the inorg. pigments or org. pigments to be compounded in the washing liquid for the backing roll include clay, kaolin, titanium dioxide, plastic pigments, such as urea resin pigments and styrene, etc. The average particle sizes of these pigments are adequately about 0.1 to 3mum. This method is particularly extremely effectual when the method is applied to the one side coating machine for the second coat of double side coated paper.

Description

Detailed Description of the Invention "Field of Industrial Application" The present invention relates to a method for efficiently cleaning the backing roll of a single-sided coating machine, and in particular to the operability of the coating machine and the resulting coated paper. The present invention relates to a backing roll cleaning method that can extremely effectively contribute to improving the quality of backing rolls.

``Prior art'' Generally, in a coating machine that manufactures coated paper, after coating one side of a base paper with a coating liquid, the excess coating liquid is scraped off using a metering device such as a blade to achieve a specified coating. The amount is coated, dried and rolled up. At that time, the coating liquid is applied in a narrower area than the inside of the base paper, leaving a part of the edge part of the paper uncoated, or coating the inside of the paper wide and then covering the excess coating on the base paper. Generally, the coating liquid transferred to the backing roll is also scraped off together with the coating liquid. The coating liquid on the backing roll coated with a width larger than the inside of the paper is not completely scraped off. For this reason, the coating liquid on the backing roll that has adhered to the inside of the paper or above is washed away with the washing water of the backing roll and discarded as paint waste water. Furthermore, it is necessary to clean the coating liquid on the backing roll that has passed through the base paper layer and adhered to it due to defects in the base paper such as holes and pinholes in the base paper. A cleaning doctor equipped with a spray, shower, etc., for cleaning with a cleaning liquid such as water or warm water is installed, and is called a Flotalin doctor. However, such a cleaning doctor cannot sufficiently clean the coating liquid on the banking roll. Furthermore, preparation,
The cleaning doctor removes foreign substances such as lees, paper dust, blanket fibers, etc. that adhere to the base paper from processes such as paper machines and winders, or aggregated resinous foreign substances such as unstable substances such as synthetic resin emulsions in the coating liquid. This may cause the doctor blade to partially float, resulting in excessive cleaning liquid on the puffing roll, or foreign matter adhering to the doctor blade may cause colored streaks on the paper surface, or even remain on the doctor blade. Because of the foreign matter, there is no amount of water that gets on the back side of the paper through the backing roll, causing various problems such as uneven drying. Incidentally, the phenomenon in which foreign matter adheres to the paper surface via the backing roll is generally referred to as scraping, and is a cause of paper breakage during operation in the coating process or serious defects in product quality.

For this purpose, improvements to backing roll cleaning devices have been proposed (Publication of Patent Publications Hei! 180269, Hei 1-180270, Hei 1-184075, etc.), but the mechanical methods proposed in these proposals are not sufficiently effective. This cannot be expected, and there is hardly any improvement effect particularly on the phenomenon of waste circulation caused by foreign substances.

``Problems to be Solved by the Invention'' In view of the above-mentioned current situation, the present inventors have endeavored to find a method for preventing the phenomenon of waste circulation (staining) on the banking roll of a single-sided coating machine, from the viewpoint of the properties of the cleaning liquid for the backing roll. As a result of repeated research, we have found that the conventional problem of paper breakage during the coating process due to the phenomenon of waste circulation, and uneven adhesion of cleaning water to the back side of the coated paper due to foreign matter adhering to the cleaning doctor. We have discovered a method that can significantly improve the resulting quality abnormalities, and have finally completed the present invention.

"Means for Solving the Problems" The present invention provides a method for cleaning a backing roll by pouring a cleaning liquid into a doctor part for cleaning the backing roll of a single-sided coating machine, in which the cleaning liquid has a solid content concentration of 0.05 to 30.
A method for cleaning a banking roll of a single-sided coating machine, characterized in that the banking roll contains a pigment in an amount of % by weight.

``Function'' Conventionally, hot water or simply factory water has been used to clean the banking roll of single-sided coating machines, and the spraying method has been changed to a high-pressure shower and the spraying area has been widened to remove waste particles. I've tried to prevent this from happening. However, with this kind of equipment correction method, it was found to be effective when the speed of the coating machine was low, but when the coating speed was 50%
In recent coating machines such as 0 m/preparative coating machines, there is hardly any cleaning effect to prevent the phenomenon of waste circulation due to foreign matter brought from the base paper or coating liquid.

In addition, in the method for preventing the phenomenon of waste rolling on the backing roll of a single-sided coating machine, regarding the effectiveness of the cleaning liquid for cleaning the backing roll, it is better to use plain water that does not contain solids, or warm water that contains detergent. , is considered to have a high cleaning effect, but if a solid substance (pigment) is intentionally included in the cleaning water as in the present invention, it may cause the backing roll to become unnecessarily dirty or deteriorate the quality of the back side of the coated paper. Naturally, it was thought that there was a risk of this, and therefore no idea was given to the use of washing water to which such pigment solids were added for washing the backing roll.

The present inventors have not only focused on methods for improving equipment, but have also focused on cleaning liquid for puffing rolls and have conducted various studies and experiments. As a result, it has surprisingly been found that the inclusion of a small amount of a specific solid substance, namely inorganic or organic pigment, in the washing water has traditionally caused paper breakage in the manufacture of coated paper, or caused serious quality problems. The inventors have discovered that the abnormal phenomenon of waste circulation in banking rolls, which has caused such problems and for which almost no improvement measures have been found, can be completely eliminated.

In addition, the phenomenon of scraps around the backing roll of a single-sided coating machine is as follows.
Of course, this is an abnormal phenomenon that does not occur with double-sided coating machines, and it occurs with abnormal defects especially during the second back coating with a so-called single-sided coating machine, which coats already coated paper. Therefore, immediate improvement measures are strongly desired.

In other words, in the case of manufacturing double-sided coated paper, during the second coating with a single-sided coating machine, the first coated surface comes into contact with the backing roll of the coating machine, so the cleaning liquid adhering to the backing roll is coated. The surface will be coated. At this time, it is extremely important that the amount of washing liquid on the banking roll is adjusted to the minimum amount possible, and that the small amount of washing liquid is also adjusted so that it adheres uniformly to the paper surface.

If the cleaning liquid adheres unevenly to the banking roll, the properties of the first coated surface, such as trapping and permeability unevenness in printability, will occur, resulting in printing abnormalities and making it impossible to obtain products with commercial value. Can not.

Therefore, the method of the present invention is most effective when applied to a single-sided coating machine for double-sided coated paper for two coats, and for single-coat coaters such as Bill Blade, Velvapa coater, Duocoat coater, etc. This is not related to so-called double-sided coating machines, which coat both sides with a double-sided coating machine.

Accordingly, the method of the present invention uses an inorganic pigment or an organic pigment in a solid concentration of 0.05 to 30% by weight, preferably 0.1 to 20% by weight as cleaning water for the banking roll of a coating machine.
, more preferably in the range of 0.1 to 10% by weight, is a very important feature not found in conventional ideas.

Incidentally, if the pigment solid content concentration in the cleaning liquid is less than 0.05% by weight, the desired effect of preventing the backing roll from becoming scum in the present invention cannot be observed, while if it exceeds 30% by weight, the cleaning doctor may not be used. Even if it works effectively, it cannot be used because the quality of the paper surface to which the cleaning solution is attached changes due to the influence of the pigment in the cleaning solution.Therefore, the concentration of the cleaning solution used has a large effect on the quality of the paper surface to which the cleaning solution is attached. At the same time, it is important to adjust and install the cleaning doctor so that the amount of cleaning liquid remaining on the backing roll surface that has passed through the cleaning doctor is as small as possible. .

In addition, in the method of the present invention, the reason why the abnormal phenomenon of waste circulation is completely eliminated by including an inorganic or organic pigment in the backing roll cleaning liquid is not necessarily clear, but it is presumed as follows. Ru.

In other words, the pigment in the cleaning liquid pushes out foreign matter adhering to the doctor of the backing roll, or the fine pigment acts as a lubricant to prevent sticky foreign matter from adhering to the doctor, so the roll surface is always clean. It is assumed that this will be maintained.

Furthermore, regarding the action and effect of pigments in this cleaning solution, it is possible to use an aqueous solution that does not contain starches such as oxidized starch and ester starch, proteins such as casein and soybean protein, or pigments such as synthetic resin emulsion. This is also supported by the fact that when the method of the present invention is used, the effect of preventing waste generation obtained by the method of the present invention is not observed at all.

In any case, according to the method of the present invention, it is possible to completely eliminate the abnormal phenomenon of waste rolling of the banking roll, and a very remarkable improvement effect can be obtained.

Effective inorganic or organic pigments used in the backing roll cleaning solution include, for example, clay kaolin, aluminum hydroxide, calcium carbonate, titanium dioxide, calcium sulfate, barium sulfate, zinc oxide, satin white, talc, calcined kaolin, and acid clay. , aluminum silicate, amorphous silica, bentonite, colloidal silica, urea resin pigments, and plastic pigments such as styrene. In addition, these pigments can of course be used alone or in combination of one or more types as appropriate, and the pigments normally used for paper making and coated paper are colored substances and coarse particles. It is preferably used because it rarely contains foreign substances such as.

The particle size of the pigment used in the method of the present invention is not particularly limited, but the average particle size is preferably 0.
In the range of about 1 to 30 μm, more preferably 0.3 to 20
The range is about μm. Incidentally, if the solid content concentration is less than 01μm, it is necessary to increase the solid content concentration, while if it exceeds 30μm, it is necessary to increase the solid content concentration.
This is not preferable since it may contain a large amount of particles or foreign matter having a particle size of m or more.

In addition, in the present invention, the p of the cleaning liquid for the backing roll is
Preferably, H is in the range of 5 to I2.

If the pH of the cleaning solution is outside of this range, there is a concern that the coated Kawahara paper that comes into contact with the cleaning solution may discolor, which is undesirable. Note that the cleaning liquid used in the method of the present invention can be used by diluting the coating liquid containing the pigment used in the production of coated paper, or by recovering the cleaning liquid and using it. This is a particularly preferred example of application because the following conditions are met. In addition, according to this method, it is possible to reuse the cleaning liquid that was coated in the coating liquid above the paper and discarded together with the cleaning liquid, so it is extremely useful for closing factory wastewater.

In this case, ingredients other than pigments, such as starches, synthetic resin latte/7x, thickeners, lubricants, dyes, etc., are mixed in, but according to the extensive experimental results of the present inventors, due to this,
The desired effects of the present invention were hardly impaired.

However, it is more preferable that the concentration of each component other than the pigment is lower than the pigment concentration.

The method of the present invention includes a blade coater, a ronto coater,
It is extremely effective when widely used in on-machine or off-machine single-sided coating machines having banking rolls, such as bar coaters, air knife coaters, and curtain coaters.

The backing roll doctor of the present invention can be any of the usual doctors such as bevel type or bend type blades, rods, and bars.

In the present invention, the base paper used for coating in the single-sided coating machine may be, for example, non-coated paper, single-sided coated paper, double-sided coated paper, etc., but is not limited to the above. Of course, this also applies to coated paper coated with multiple layers as described above.

Types of coated paper include coated paper for printing such as Hui coated paper, medium-quality coated paper, art paper, coated paper, super art paper, matte paper, and dull paper, thermal recording paper, pressure-sensitive copying paper, and ink. Not only general coated paper and information industry paper such as jet recording paper, but also coatings such as synthetic paper, film, metallized paper, various shielding papers, special papers such as aromatic paper, etc., or their undercoat, intermediate layer, and topcoat. It can also be widely used in coatings such as overcoats. Of course, it is more effective to use the method of the present invention in combination with a conventionally known mechanical cleaning method as described above, and there is no limitation thereto.

"Example" The present invention will be described in more detail with reference to Examples below, but of course the scope is not limited thereto. In addition, "parts" and "%" in the examples indicate "parts by weight" and "% by weight", respectively, unless otherwise specified.

Example I A raw material prepared by adding 1.5 parts of rosin sizing agent, 0.5 parts of cationic starch, 10 parts of talc, and 3 parts of hand to a pulp composition of 60 parts of bleached NKP and 40 parts of bleached [, KP] was made into fourdrinier paper. The paper was made with a machine at a speed of 650 m/min, and the oxidized starch was coated with a size press so that the solid content after drying was 2.6 g/% on both sides.
5 g/- of base paper was obtained.

Separately, as pigments, 70 parts of kaolin (trade name - W-90/average particle diameter of about 0.5 μm; manufactured by EMC), atomized heavy calcium carbonate (trade name - Kajotaru 90/average particle diameter of about 0.7 μm) ; manufactured by Fuji Kaolin Co., Ltd.) 20 parts (each solid content),
10 parts (solid content) of Satin White dispersion (trade name - Sachin White/manufactured by Shiroishi Kogyo Co., Ltd.) were blended, 0.2 parts of sodium polyacrylate was added, and dispersed using a Coles dispersion machine, solid content concentration 66. % slurry was prepared. Add 2 parts of phosphoric acid modified starch (solid content) to this pigment slurry as an adhesive.
and modified styrene-butadiene copolymer latex 15
(solid content) and then add water to make the solid content concentration 60%.
A coating liquid was prepared. The coating liquid obtained in this way was applied to the above-mentioned base paper using two single-sided blade coaters each having a backing roll diameter of 920 mm, a cleaning shower, and a cleaning doctor. Coating was carried out at a coating speed of 900 m/min to give a coating density of 2 g/m, and after drying with a dryer at 120 C, the back side was coated in the same manner with a second coater to obtain coated paper for double-sided printing. I got it. The resulting coated paper was finished by passing it through a 14-stage super calender.

The cleaning liquid for the banking roll was used by diluting the coating liquid to the above-mentioned total pigment concentration of about 3%. As much of the cleaning solution as possible was collected, foreign matter was filtered out, and the solution was circulated for use. Although the operation was carried out under the above conditions for 24 hours, no abnormality in waste circulation due to foreign matter occurred, and the obtained coated paper was used for four-color printing and offset printing.
) A double-sided printing test was carried out using a printing machine at a speed of 6000 sheets/min, and no abnormalities were observed in terms of quality.

Example 2 Kaolin (Amasin 88; average particle size 0.2 μm/The Caulim da Am
The same procedure as in Example 1 was carried out except that a cleaning solution containing 20% (manufactured by azonla Lida) was used. Although the machine was operated under these conditions for 24 hours, no abnormality in waste circulation due to foreign matter occurred, and no abnormality was observed in the quality of the coated paper obtained.

Example 3 Example 1 except that an aqueous liquid containing 0.1% of heavy calcium carbonate (pigment) with an average particle size of 20 μm and 0.5% of sodium carboxymethyl cellulose as an anti-settling agent was used as the cleaning liquid. It was carried out in the same manner. Although the operation was carried out under these conditions for 24 hours, no abnormality in waste circulation due to foreign matter occurred, and no abnormality was observed in the quality of the obtained coated paper.

Comparative Example 1 The same procedure as Example I was carried out except that hot water of about 40° C. was used as the cleaning liquid.

During the operation, a phenomenon of waste circulation due to foreign matter occurred, and the paper broke after about 3 hours due to this abnormality, so the coater was cleaned.

A printing test was conducted on the coated paper obtained at this time using a four-color offset printing machine, and as a result, linear trapping unevenness occurred on the paper surface where the cleaning liquid from the backing roll was attached, especially during the second coating process. did.

Example 4 A pulp slurry consisting of 90 parts of bleached NKPIO and 90 parts of bleached LKP was added with 8 parts of talc per pulp fiber and rosin size of 0.
A paper stock prepared by adding 5 parts and 3 parts of sulfuric acid was applied to a Fourdrinier paper machine to make paper, and then oxidized starch was size-pressed to the base paper so that the coating amount after drying was 2 g/rd. A base paper for thermal copying paper weighing 45 g/d was obtained.

Separately, as an intermediate layer coating liquid for thermal copying paper, 100 parts of Bakedurei (trade name: Ancilesox/manufactured by EMC),
A coating liquid with a solid content of 43% was prepared from a composition of 100 parts of styrene-book diene copolymer latex (trade name: D o w 1571/manufactured by Asahi Kaei Kogyo Co., Ltd.) and 50 parts of a 2% aqueous solution of carboxymethyl cellulose. did. The coating liquid thus obtained was coated on the base paper for thermal copying paper obtained using the Fourdrinier paper machine using an on-machine roto coater so that the coating amount after drying was 1 g/rd. , and dried to form an intermediate layer. The coating speed at this time was 600 mm/min.

Note that the intermediate layer coating liquid was diluted to have a pigment concentration of about 7% and used as the cleaning liquid for the backing roll. The cleaning solution was collected as much as possible to remove foreign substances, and then used for circulation. Although the operation was carried out under these conditions for 24 hours, no abnormality in waste circulation due to foreign matter occurred, and no abnormality was observed in the quality of the obtained intermediate coated paper.

Comparative Example 2 The same procedure as in Example 4 was carried out except that factory water was used as the cleaning liquid. Unfortunately, about 4 hours after starting the operation, the entire coater had to be washed and cleaned due to the occurrence of waste particles and uneven coating on the paper.

Example 5 Using the on-machine roto coater used in Example 4, the following was applied to base paper for an intermediate coating layer for thermal copying paper coated with the same intermediate layer coating liquid obtained in Example 4. Record N coating liquid was applied.

(Preparation of recording layer coating liquid) ■ Preparation of liquid A 3-(N-cyclohexyl-N-methylamino)-6-
Methyl-7-phenylaminofluorane
10 parts 1.2-bis-(3-methylphenoxy)ethane 15 parts 5% methylcellulose aqueous solution 15 parts 80 parts This composition was ground in a sand mill until the average particle size was 3 μm.

■ Preparation of Solution B 4.4° -Isopropylidenediphenol 30 parts Methylcellulose 5% aqueous solution 30 parts Water
70 copies! fJ1 Kaimono was ground with a sand mill until the average particle size was 3 μm.

120 parts of liquid A, 130 parts of liquid B, 30 parts of amorphous silica, 2
A recording layer coating liquid was prepared by stirring and mixing 150 parts of a 0% oxidized starch aqueous solution and 55 parts of water.

Then, the heat-sensitive recording layer was coated using an off-machine blade coater so that the coated layer after drying was 4 g/m', and after drying, the heat-sensitive recording layer was subjected to supercalender treatment to obtain a heat-sensitive recording material.

In this case, 100 parts of heavy calcium carbonate with an average particle diameter of 25 μm was added to the cleaning solution for the banking roll per 100 parts of the solid content of the recording layer coating solution, so that the pigment concentration was approximately 0.1.
% washing solution was used. After collecting as much of the cleaning solution as possible and removing foreign matter, it was circulated and reused. Although the machine was operated under these conditions for 24 hours, no abnormality in waste circulation due to foreign matter occurred, and no abnormality was observed in the quality of the coated paper obtained.

Comparative Example 3 The same procedure as in Example 5 was carried out except that factory water was used as the cleaning liquid. Approximately 1 hour after the start of operation, scum generation occurred, and an abnormal drying profile occurred due to uneven coating of water on the back surface.As a result, the heat-sensitive coating layer in the over-dried area became colored by heat, resulting in black streak-like quality abnormalities. As a result, operations were halted.

Example 6 A base paper of 40 g/rrl as the base paper for pressure-sensitive copying paper was coated with a color developer coating liquid for the base paper having the following composition using an off-machine blade coater to a dry weight of 5 g/nf. Painted.

(Composition of lower paper coating layer) Aluminum hydroxide 65 parts Zinc oxide 20 parts 3.5-di(α-
Melt of zinc methylbenzyl salicylate and α-methylstyrene/styrene copolymer (melt ratio 80/20)
15 parts polyvinyl alcohol aqueous solution (solid content) 5 parts water 3
20 parts (solid content) of carboxy-modified styrene-butadiene copolymer latex was added to a dispersion obtained by crushing 00 parts with a ball mill for 24 hours. Further, the coating speed at this time was 600 mm/min.

Note that the lower paper coating liquid was diluted to about 0.2% and used as the cleaning liquid for the banking roll. After collecting as much of the cleaning solution as possible and removing foreign matter, it was circulated and reused. Under this condition 2
Although the operation was carried out for 4 hours, there was no occurrence of waste λ due to foreign matter, and no abnormality was observed in the quality of the coated paper obtained.

Comparative Example 4 The same procedure as in Example 6 was carried out except that factory water was used as the cleaning liquid. Approximately 2 hours after the start of operation, scraping occurred, which caused uneven coating on the paper surface and paper breakage, which forced the entire coater to be washed and cleaned.

"Effects" As is clear from the examples, by implementing the present invention, abnormalities in the quality of the paper surface due to excessive or insufficient cleaning liquid due to waste around the backing roll of the coating machine during coating, and decrease in operability due to paper breakage. We were able to completely eliminate these problems.

[Brief explanation of drawings]

FIG. 1 is a typical schematic diagram for carrying out the method of the present invention. (1) Base paper (2) Banking roll (3) Applicator roll (4) Color bread (painting)

Claims (3)

[Claims] (1) A method of cleaning a backing roll by pouring a cleaning liquid into a doctor part for cleaning the backing roll of a single-sided coating machine, characterized in that the cleaning liquid contains a pigment in a solid concentration of 0.05 to 30% by weight. How to clean the backing roll of a single-sided coating machine. (2) The method for cleaning a backing roll of a single-sided coating machine according to claim (1), wherein the pigment has an average particle diameter of 0.1 to 30 μm and a solid content concentration of 0.1 to 20% by weight. (3) In coating double-sided coated paper that is coated on both sides with a plurality of single-sided coaters, the cleaning method according to claim (1) or (2) is applied to the backing roll of the double-sided coater. How to clean the roll.