JPH03279499A - Production of coated paper by three-roll coater - Google Patents

Abstract

PURPOSE:To carry out uniform coating by making peripheral speed of applicator roll based on feed rate of paper stock, peripheral speed relationship of three rolls and gaps between the applicator roll and other two rolls in specific ranges. CONSTITUTION:A coating compound supplied from a coating compound tank T to a pick-up roll R2 is transferred to an applicator roll R1 rotating in normal direction, thickness of coating compound layer transferred is regulated to given thickness by a metering roll R1 rotating in the opposite direction, the coating compound is continuously traveled while being slid on the applicator roll in the normal direction and applied to paper stock. Rolls having 350-450mm diameters are used as the three rolls, the peripheral speed of R1 is 20-30 feed speed of paper stock, the peripheral speed of R2 is 40-60% that of R1, the peripheral speed of R3 is 60-80% that of R1, gap t1 between R1 and R2 is 35-400mum and gap t2 between R1 and R2 is to make t1-t2 5-50mum.

Description

Detailed Description of the Invention (Industrial Field of Application) The present invention applies various paints to a paper material that is continuously running using a so-called three-roll coater using three rolls to produce coated paper, This invention relates to methods for producing various coated papers such as pressure copying paper, thermal recording paper, and electrostatic recording paper.

(Prior Art) In general, a three-roll coater used for coating paper materials has three rolls: an applicator roll R1, a pickup roll R2, and a metering roll R3, as shown in the drawing. The paint collected from the paint tank T at R2 is transferred to the applicator roll R1 which rotates in the forward direction, and the thickness of this transferred paint layer is regulated to a predetermined thickness by the metering roll R3 which rotates in the reverse direction. The paint is applied to the continuously running paper material P while slidingly contacting the applicator roll R1 in the forward direction. R4 and R5 are rubber or metal roll guides that guide the feeding of the paper material P before and after the applicator roll R1.

However, in the past, the above three rolls R1 to R3
Applicator rolls with a diameter of 250 to 300 m+* are commonly used, and the driving conditions in that case vary to some extent depending on the physical properties of the paint, but usually the circumferential speed v1 of the applicator roll R1 is set to 40 m + the paper material feed speed Vp. ~45%, and set the circumferential speed V of the big unroll R2 and the applicator roll R3 to be 40 to 50% of the circumferential speed ■1 of the applicator roll R1, and V<■, Also applicator roll R1 and pink unroll R2
It has been common practice to set the gap t1 between the applicator roll R1 and the metering roll R3 to a value smaller than t by about 300 .mu.-, and the gap t2 between the applicator roll R1 and the metering roll R3 to a value smaller than t by about 30 to 50 .mu.-.

(Problem Fa to be solved by the invention) However, recently, for the purpose of improving drive stability and durability, the three rolls R1 to R3 have been
There is an opportunity to introduce large-diameter three-roll coaters for coated paper.

However, when coating is performed using such a three-roll coater with a large roll diameter, applying the coating conditions of the conventional three-roll coater with a small roll diameter, that is, the circumferential speed and roll gap conditions, results in uneven coating. It has been found that this inevitably causes a problem in that streaks of paint are formed on the paper surface and the quality of the coated paper is significantly degraded.

In view of the above-mentioned circumstances, the present invention investigates conditions that enable uniform coating without causing uneven coating when using a three-roll coater with a large roll diameter.
The purpose of the present invention is to provide a method for stably producing high-quality coated paper.

(Means for Solving the Problems) In order to achieve the above object, the inventors of the present invention have conducted detailed experimental research and found that in order to perform uniform coating with a three-roll coater with a large roll diameter, the conventional Compared to the coating conditions using a three-roll coater with a small roll diameter, the relative sliding speed between the applicator roll and the paper material is significantly increased.
In addition, it is basically necessary to set the gaps between the applicator roll and the pink am roll and the metering roll to be large, and in particular, it is necessary to set the relative sliding speed and the relationship between the gap and the circumferential speed of the three rolls within a specific range. It has been found that coating unevenness can be completely prevented in some cases.

That is, in the method for producing coated paper using a three-roll coater according to the present invention, paint collected from a paint tank in a paint tank is transferred to an applicator roll that rotates in the forward direction, and the paint layer of this transferred I paint layer is transferred. After regulating the thickness to a predetermined thickness using a metering roll that rotates in the opposite direction, the paint is applied to a paper material that is continuously running while sliding in the forward direction on the applicator roll. ~450mm diameter is used, and the circumferential speed of the applicator roll is set to 20-30% of the paper feed speed.
Adjust the circumferential speed of the pickup roll to 4 of the applicator roll.
0 to 60%, the circumferential speed of the metering roll to 60 to 80% of that of the applicator roll, the gap t between the applicator roll and the pickup roll to 350 to 400μ, and the gap t2 between the applicator roll and metering roll to the above gap L+ tz A configuration is adopted in which each setting is set to 5 to 50 .mu.I.

(Function) The coating conditions in the manufacturing method of the present invention are summarized as follows using reference numerals in the drawings.
, R3 has a diameter of 350 to 450-, and if the feeding speed of the paper material P is Vp, then the roll R1 (D circumferential speed V+=0.
2Vp ~ 0.3VpO-R2 (7) Peripheral speed vz=0.
4V+~0.6V1o-le R30) Peripheral speed v3-0.6V
, ~0.8■.

Gap t between rolls R1 and R2, -350 to 400.1
7 m Gap between rolls R1 and R3 t2 = (t+-5) to (t, -50) 8 layers, that is, in this method, the gap is 1. ．． 1. By making both of them larger than in the case of a conventional three-roll coater consisting of small-diameter rolls, the amount of paint transferred to the applicator roll R1 is larger than that of the pink-up 0-/I/R2, and the metering roll In addition to setting the paint thickness adjusted by R3 to a large value, the transfer of the paint from the paint tank T to the applicator roll R1 and the above thickness setting are made stably due to the relationship between the circumferential speeds of the three rolls R1 to R3. The conditions are selected. On the other hand, the circumferential speed V of the applicator roll R1 relative to the feed speed Vp of the paper P is much smaller than in the case of a conventional three-roll coater consisting of small diameter rolls. The relative sliding contact speed with R1 is high. Therefore, although the amount of paint supported per unit area of the applicator roll R1 is large, it is offset by the large sliding contact area of the paper material P per unit area, and the coating amount of the paper material P is set appropriately. Ru.

Therefore, in a three-roll coater with a large roll diameter, as mentioned above, by making the applicator roll R1 quickly rub the paper material P with a large amount of coating material, the coating property on the paper material P is basically improved. In particular, it has been confirmed that coating unevenness can be completely prevented by selecting the coating conditions described above.

(Example) Rolls R1 to R3 are 400 as a three-roll coater.
Two types of devices were used, one with a diameter of 440 mm and the other with a diameter of 440 mm, and the circumferential speeds of rolls R1 to R3 and the roll gap of 1. ．． 1. Coating was carried out for the production of information recording paper under various conditions with various changes, and uniform coating properties were determined by observing the occurrence of uneven coating (fading) on the coated paper surface. The results shown in the table were obtained.

Coating conditions other than those listed> Feed speed Vp of paper material P...790 m/min Diameter of guide rolls R4, R4...212 Angle...4 with respect to horizontal
5 degree paint (water-based): viscosity 5-1 ocps.

Density 18-19% <Evaluation of uniform coating property> O... No uneven coating at all Δ... Slight uneven coating ×... Severe uneven coating Table 1, o-R1 to R3 (7) Diameter 400 wa 2nd
Table: The diameter of rolls R1 to R3 is 440. From the results in Tables 1 and 2 above, it can be seen that both the three-roll coater with a diameter of 400 and the three-roll coater with the same diameter of 440 The peripheral speed ■ of R1 is 2° to 30% of the feed speed Vp of the paper material P, and the peripheral speed ■2 of roll R2 is ■1
60-80% of roll R3 peripheral speed ■3 is 60-80% of ■1
80%, gap t is 350-400 tt el, t +
When all the conditions of L t = 5 to 50 pm are satisfied, uneven coating can be completely prevented, and the more these conditions are deviated from, especially when the circumferential speed 1 and the gap t1 are outside the above range, the more uneven coating becomes. I understand.

(Effects Unique to the Invention) According to the method of the present invention, in coating paper materials using a large three-roll coater with a roll diameter of 350 to 450 m, the circumferential speed of the applicator roll relative to the feeding speed of the paper material is 3. By setting the circumferential speed of the two rolls and the gap between the applicator roll and the other two rolls within specific ranges, uniform coating without uneven coating can be achieved continuously, resulting in high quality and stable coating. Coated paper can be prepared.

[Brief explanation of the drawing]

The drawings are schematic diagrams showing the process of coating paper materials using a three-roll coater. P...Paper material, R1...Applicator roll, R2
...Pick-and-roll, R3...Metering roll, T...Paint tank, Vp...Feed rate, ■, ~V. ...Circumferential speed, 11 +Lt...Gap.

Claims (1)

[Claims] The paint picked up from the paint tank by a pickup roll is transferred to an applicator roll that rotates in the forward direction, and the thickness of this transferred paint layer is regulated to a predetermined thickness by a metering roll that rotates in the opposite direction. When coating the paper material that is continuously running while sliding in the forward direction on the applicator roll, the three rolls mentioned above have a diameter of 350 to 450 mm, and the peripheral speed of the applicator roll is set at 20 times the feed speed of the paper material. ~30%, the circumferential speed of the pickup roll is 40-60% of the applicator roll, and the circumferential speed of the metering roll is 60-80% of the applicator roll.
%, the gap t_1 between the applicator roll and the pickup roll is 350 to 400 μm, and the gap t_2 between the applicator roll and metering roll is the above gap t_1
- A method for producing coated paper using a three-roll coater, characterized in that t_2 is set to 5 to 50 μm.