JPH0985144A - Production of coated paper for printing and apparatus for production therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To lessen the occurrence of uneven application in the case a high- viscosity coating liquid or high-speed coating using a small-sized device by applying the coating liquid transferred onto a top applicator roll on a web while pressurizing a nip of an applicator roll, then winding this web around the peripheral surface of this top applicator roll. SOLUTION: A pressurizing roll 1 is held into pressurized contact freely rotatably with the upper part of the top applicator roll 2 and the web 4 is respectively inserted into the nip formed between the upper part of the top applicator roll 2 and the pressurizing roll 1 and the nip between the top applicator roll 2 and a bottom applicator roll 3 and is then moved by being wound around the peripheral surface of the bottom applicator roll 3. At this time, the coating liquid transferred to the top applicator roll 2 is applied on one surface of the web 4 by the nip formed between the upper part of the top applicator roll 2 and the pressurizing roll 1 and the coating liquid is applied on the other surface of the web 4 in the hip between the lower part of the top applicator roll 2 and the upper part of the bottom applicator roll 3.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for manufacturing a coated paper for printing, more specifically, a method for applying a coating liquid on the surface of a coated paper, in which printing unevenness is minimized. The present invention relates to a method capable of producing a coated paper and an apparatus capable of producing a coated paper for printing with less coating unevenness by a relatively small applicator roll.

[0002]

2. Description of the Related Art Various types of roll coating devices such as a pond type roll coater and a gate roll coater are often used as a device for producing coated paper for printing. The pound roll coater is composed of a pair of applicator rolls whose axes that can rotate at the same speed as the web are parallel to each other, and the outer peripheries of the two applicator rolls contact each other with a line to form a nip. The line connecting the centers of the applicator rolls is horizontal or slightly inclined, and the nip serves as a pond (powder) of the coating liquid, and the web passes through the pond to excessively adhere the coating liquid to the web. Then, it is squeezed at the nip to adjust the coating amount and penetrate the web.

However, a drawback of the pond type roll coater is that, when a high-viscosity coating liquid is applied, the patter-like uneven coating (orange peel) becomes more intense as the coating speed increases. As shown in FIG. 4, the coating unevenness is caused as the web 41 moves away from the contact point (transition point) 43 of the nip 42, and the coating liquid 45 that has been sandwiched between the surface of the applicator roll 44 and the web 41 is applied to the applicator. It occurs when the roll 44 surface side and the web 41 surface side are forcibly torn. Especially when the coating liquid has a strong adhesive force, the applicator roll
4 It is difficult to peel off from the surface, and coating unevenness is likely to occur due to the fact that a trace of breakage of the coating liquid layer when pulling or tearing the thread remains.

Further, the smaller the diameter of the applicator roll 44, the larger the angle (hereinafter referred to as the opening angle) θ of the wedge-shaped coating liquid formed by the surface of the applicator roll 44 and the web 41 on the exit side of the nip 42, and the coating liquid becomes larger. Is torn in a short time, so coating unevenness is likely to occur. Particularly, when the coating speed is high, uneven coating tends to be a problem.

Conventionally, in order to prevent coating unevenness in high-speed coating, the diameter of the applicator roll 44 is increased to decrease the opening angle θ of the coating liquid formed by the web 41 and the applicator roll 44 at the exit of the nip 42. The coating solution should be peeled off as gently as possible. For this reason, the diameter of the applicator roll 44 increases as the speed of the coater increases, but as a result, power and installation space increase, and equipment costs cannot be avoided.

As shown in FIG. 5, the gate roll coater is composed of a pair of applicator rolls consisting of a top applicator roll 51 and a bottom applicator roll 52, an inner roll 53, an outer roll 54, an inner roll 55 and an outer roll 56. ing.

An inner roll 53 is circumferentially in contact with the top applicator roll 51, and an outer roll 54 is in contact with the inner roll 53. The bottom applicator roll 52 has an inner roll 53. An outer roll 56, which is in circumferential contact with the roll 55 and is in circumferential contact with the inner roll 55, is provided. The nip between the inner roll 53 and the outer roll 54 and the inner roll 55 and the outer roll 56 are provided.
Of the coating liquid (pound) 57a,
57b are formed.

Inner roll 53 and outer roll 54
The coating liquid of the pond 57a in between is transferred from the inner roll 53 to the peripheral surface of the top applicator roll 51, the web 58 is coated on one surface at the nip between the top applicator roll 51 and the bottom applicator roll 52, and the inner roll 55 The coating liquid of the pound 57b between the outer rolls 56 is transferred to the bottom applicator roll 52 via the inner roll 55 after the web 58 is inserted into the nip, and is applied to the other surface of the web 58.

In the above-mentioned gate roll coater, when the coating amount is adjusted, the gap between the outer roll and the inner roll is changed or the peripheral speed difference is changed. There is no choice but to adjust depending on the concentration and viscosity. In particular, as the coating amount is increased and the viscosity increases, the occurrence of coating unevenness is inevitable for the same reason as the pond type roll coater at higher speeds. Increasing the size was inevitable.

[0010]

DISCLOSURE OF THE INVENTION The present invention solves a serious defect in quality such as coating unevenness in high-speed coating and deterioration of working environment due to generation of mist, and uses a small apparatus to
In particular, it is an object of the present invention to provide a coating method and a coating apparatus for printing coated paper which can be coated at high speed with a pond type roll coater, a gate roll coater or the like.

[0011]

According to a first aspect of the present invention, in applying both sides of a web, the nip of an applicator roll consisting of a pair of a top applicator roll and a bottom applicator roll is transferred to the top applicator roll while pressing the nip. This is a method for producing a coated paper for printing, which is applied on one side of a web and then wound around the peripheral surface of a top applicator roll.

According to a second aspect of the present invention, in a coater comprising a top applicator roll and a bottom applicator roll, a pressure roll is rotatably pressed onto the upper part of the top applicator roll, and a web has the upper part of the top applicator roll and the pressure roll. The nip formed in and the top applicator roll and the nip of the bottom applicator roll are respectively inserted, and the peripheral surface of the top applicator roll is wound between the two nips, and on the other hand, the coating liquid transferred to the top applicator roll. Is an apparatus for producing a coated paper for printing, which is configured so that it can be applied to a web at a nip formed by a top applicator roll and a pressure roll.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows an embodiment of the present invention device, FIG. 2 shows another embodiment of the present invention device, and FIG. 3 shows another embodiment of the present invention device. The present invention will be specifically described with reference to FIG.

FIG. 1 shows an example of an apparatus when the present invention is applied to a gate roll coater, in which a top applicator roll 2 and a bottom applicator roll 3 are in circumferential contact with each other.
It is supposed to be rotatable, and the top applicator roll 2
The pressure roll 1 is rotatably pressed onto the upper part of the, and the pressure roll 1, the top applicator roll 2 and the bottom applicator roll 3 are arranged on a vertical line.

An outer roll 7 is provided on the peripheral surface on the side of the top applicator roll 2 so as to be in contact with the inner roll 5 and to be in contact with the inner roll 5 so as to rotate, and the inner roll 5 and the outer roll 7 are rotated together. Has a pond (liquid pool) 12a formed in its nip, and similarly, the inner roll 6 is in contact with the peripheral surface on the side of the bottom applicator roll 3 and
And an outer roll 8 which can rotate in circumferential contact with each other is installed, and a pond 12b of the coating liquid is formed in a nip between the inner roll 6 and the outer roll 8. In addition, in FIG.
Reference numeral 9 is a coating liquid supply nozzle, 10 is a coating liquid, 11 is a transition point, 13 and 14 are color pans, and 15 is a roll cleaning doctor.

To apply the coating liquid onto the web 4, the web 4
Is passed through the nip between the pressure roll 1 and the top applicator roll 2, and is wound around the peripheral surface of the top applicator roll 2, and then passed through the nip between the top applicator roll 2 and the bottom applicator roll 3, Wrap around the surface.

On the other hand, the coating liquid 10 is supplied from the coating liquid supply nozzle 9 to the ponds 12a and 12b, respectively.
Is transferred from the pounds 12a of the inner roll 5 and the outer roll 7 to the inner surface of the inner roll 5 by the rotation of the inner roll 5, and is transferred to the outer surface of the top applicator roll 2 via the inner surface of the inner roll 5. , The web 4 is applied to one side of the web 4 when passing through the nip between the pressure roll 1 and the top applicator roll 2. Similarly, the coating liquid of the pound 12b is transferred onto the peripheral surface of the bottom applicator roll 3 via the peripheral surface of the inner roll 6, and when the web 4 is inserted through the nip between the top applicator roll 2 and the bottom applicator roll 3. On the other side of the web 4.

The nip between the pressure roll 1 and the top applicator roll 2 and the nip between the top applicator roll 2 and the bottom applicator roll 3 pass through the nip because the pressure roll 1 is pressed against the top applicator roll 2. The coating liquid applied to each of the webs 4 rapidly and sufficiently penetrates, and then rapidly solidifies while moving while being wound around the peripheral surface of the top applicator roll 2 and the bottom applicator roll 3.

That is, according to the present invention, since the pressure roll 1, the top applicator roll 2, and the bottom applicator roll 3 are in pressure contact with each other, the nip between the pressure roll 1 and the top applicator roll 2 and the top applicator roll 2 And the nip of the bottom applicator roll 3 is clamped, the web 4 passing through the nip is clamped more strongly than before, and the coating solution is rapidly dehydrated and penetrated. Moreover, after passing through the nip, the coating liquid is wound around the peripheral surface of the top applicator roll 2 or the bottom applicator roll 3 and moves, so that the coating liquid rapidly solidifies during that period and the generation of mist due to the coating liquid can be reduced.

Further, when the solidified material of the coating liquid which is not transferred to the web 4 and adhered to the peripheral surface of the top applicator roll 2 and the peripheral surface of the bottom applicator roll 3 and solidified remains, it is caused by the solidified material. There is a risk of uneven coating. Therefore, if a roll cleaning doctor 15 is attached to each of the peripheral surfaces of the top applicator roll 2 and the bottom applicator roll 3 and water is supplied between the cleaning doctor 15 and the peripheral surface of the applicator roll, the doctor 15 can easily remove the stripping agent. can do. Although FIG. 1 shows an apparatus for producing double-sided coated paper, it can be easily applied to one side of a web by omitting the application means of either the top applicator roll 2 or the bottom applicator roll 3.

The web used in the present invention is high-quality paper, medium-quality paper, waste paper, newspaper, paperboard, coated paper, synthetic paper or plastic film. The coating solution is not particularly limited, and pigments, binders, sizing agents and other various additives can be used alone or in combination. For example, natural adhesives such as oxidized starch, etherified starch, esterified starch, oxygen-modified starch, casein, various copolymers such as styrene / butadiene, vinyl acetate / acrylic or ethylene / vinyl acetate, polyvinyl alcohol. A synthetic resin adhesive such as a maleic anhydride copolymer or an acrylic acid / methyl methacrylate copolymer, a natural or synthetic sizing agent, or a mixture thereof is used.

The pigment-containing coating liquid contains kaolin, clay, calcium carbonate, satin white, titanium oxide, aluminum hydroxide, zinc oxide, calcium sulfate, plastic pigment, etc. as a pigment, and a styrene-butadiene-based or vinyl acetate binder. -Acrylic, ethylene / vinyl acetate-based copolymers, polyvinyl alcohol, maleic anhydride copolymers, acrylic acid-methyl methacrylate-based copolymers, etc., synthetic resin adhesives, oxidized starch, etherified starch, It is composed of one or more natural adhesives such as esterified starch, oxygen-modified starch, and casein, and optionally contains a thickener, a water retention agent, a water resistant agent, and the like, if necessary. The solid concentration of the coating solution is 0.5
~ 70%, viscosity 3 to 5,000 cps (B type viscometer, 6
(0 rpm, 50 ° C.) is used, and the coating amount of the coating liquid is about 0.1 to 30 g / m ^{2 in an} absolutely dry state.

FIG. 2 shows another apparatus in which the present invention is applied to a gate roll coater (in FIG. 2, the same symbols as those in FIG. 1 are the same members), and the uppermost pressure roll 1 is the bottom. It is located on the vertical line of the applicator roll 3,
The top applicator roll 2 is arranged at a position slightly off the vertical line. In this apparatus, the web 4 is suitable because the winding length of the top applicator roll 2 and the bottom applicator roll 3 becomes short, and the coating step can be shortened when applying a low-viscosity coating liquid, which contributes to productivity.

FIG. 3 shows another apparatus in which the present invention is further applied to a gate roll coater (in FIG. 2, the same symbols as those in FIG. 1 are the same members), and the pressure roll 1 is the uppermost part. It is arranged at the bottom. This device is advantageous in the case of highly viscous paint or high-speed application because the pressing force of the nip between the pressure roll 1 and the top applicator roll 2 and the nip between the top applicator roll 2 and the bottom applicator roll 3 becomes stronger. . 1 to 3 described above.
All of the above are applied to a gate roll coater, but the same can be applied to a pound roll coater.

Next, the conditions and results of coating when a coated paper is manufactured using the apparatus shown in FIG. 1 will be specifically described with reference to the following examples.

【Example】

Example 1 Using the apparatus of FIG. 1, a coating solution having the following composition was used for a high-quality paper having a basis weight of 51 g / m ² and a coating amount of 10 g / m ² on each side was applied at a coating speed of 600 m / min. Created.

A) Coating liquid 1st class kaolin 20 parts 2nd class kaolin 30 parts Heavy calcium carbonate 50 parts Styrene-butadiene latex 12 parts Corn starch 7 parts Sodium hydroxide 0.03 parts Polyacrylic dispersant 0.1 part Solid content concentration of coating liquid 60% b) Coating conditions (1) Applicator roll diameter 610mm (2) Inner roll diameter 450mm (3) Pressure roll diameter 450mm Under the above conditions, the inner and outer rolls rotating at 90% of the peripheral speed of the applicator roll Filled the nip. Compared with conventional gate rolls, less coating unevenness occurred and the scattering of mist of coating liquid was reduced.

Comparative Example 1 The same coating solution as in Example 1 was used, and a coating test was conducted using a normal gate roll coater without a pressure roll. When the coating speed was 600 m / min, uneven coating (orange peel) occurred.

[0028] was oxidized starch 10% solution simplex 0.5 g / m ² coating using the same device as in FIG. 1 quality paper in the Example 2 basis weight 43 g / m ^2. The peripheral speed of the inner roll is 540m at a coating speed of 600m / min.
/ Min. As a result, mist was less generated and coating unevenness was less than in a normal gate roll coater. Comparative Example 2 Coating was performed using a normal gate roll coater under the same conditions as in Example 1. The mist was severely generated and uneven coating was also generated.

Table 1 shows a comprehensive evaluation of occurrence of coating unevenness and mist in Examples 1 and 2 and Comparative Examples 1 and 2.

[Table 1] Note) Evaluation of uneven coating: Two colors of RI are used. 5 points is the best for the evaluation.

[0030]

[Effect] As described above, the present invention applies the coating liquid transferred to the top applicator roll to both sides of the web while applying pressure to the pair of applicator rolls consisting of the top applicator roll and the bottom applicator roll,
Since it is wrapped around the circumference of the top applicator roll or bottom applicator roll, the penetration of the coating liquid into the web is fast, and the solidification of the coating liquid is also rapid, which reduces the occurrence of uneven coating and mist as in the past. be able to. Further, various coated papers can be produced by adjusting the pressure of the applicator roll according to the type of various webs, pigment-containing paints, and the like.

Further, the apparatus of the present invention is a simple means of pressurizing the applicator roll by pressing the pressurizing roll onto the top applicator roll, and further winding it around the peripheral surface of the top applicator roll or the bottom applicator roll. Since the coating liquid is dehydrated and solidified rapidly, the coated paper can be manufactured with a small device at a low cost and in a small space.

Further, since the apparatus of the present invention can be easily applied to a conventional pond type rotor or gate roll coater, etc., it is a small apparatus with low cost.
Moreover, the excellent action and effect of producing a highly versatile coated paper in a small space can be achieved.

[Brief description of drawings]

FIG. 1 is a schematic front view of an example of the device of the present invention.

FIG. 2 is a schematic front view of another device of the present invention.

FIG. 3 is a schematic front view of still another device of the present invention.

FIG. 4 is an explanatory diagram when peeling the web.

FIG. 5 is an explanatory diagram of a conventional gate roll coater.

[Explanation of symbols]

 1: Pressure roll 2: Top applicator roll 3: Bottom applicator roll 4: Web 5,6: Inner roll 7,8: Outer roll 9: Coating liquid supply nozzle 10: Coating liquid 11: Transition point 12a, 12b: Pound 13, 14: Color pan 15: Doctor for roll cleaning

Claims (2)

[Claims] 1. When applying both sides of a web, after applying a coating liquid transferred to the top applicator roll to the web while pressurizing a nip of an applicator roll consisting of a pair of a top applicator roll and a bottom applicator roll, A method for producing a coated paper for printing, which comprises winding the top applicator roll around the peripheral surface thereof. 2. A coater comprising a top applicator roll and a bottom applicator roll, wherein a pressure roll is rotatably pressed onto the top of the top applicator roll, and a web is a nip formed by the top of the top applicator roll and the pressure roll. And the nip of the top applicator roll and the bottom applicator roll are respectively inserted, and the peripheral surface of the top applicator roll is wound between the two nips, while the application liquid transferred to the top applicator roll is the top of the top applicator roll. An apparatus for manufacturing a coated paper for printing, characterized in that it can be applied to a web by a nip formed by a pressure roll.