JP2882889B2 - Coating method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for applying a coating liquid on a paper coater of a papermaking machine.

[0002]

2. Description of the Related Art FIG. 3 shows a short dowel time coater which is one of the conventional coating methods. A web (paper) is formed on the outer periphery of a backing roll 2 having an elastic body 1 made of rubber or the like wound on the outer peripheral surface. 3 is wound around and transferred, and the coating liquid 6 is blown vertically upward toward the lower surface of the paper 3 at the lower part of the outer periphery of the backing roll 2,
A blowing device 5 for adhering the coating liquid 6 to the paper surface is provided, and the coating device 6 is integrated with the blowing device 5 to remove excess coating liquid 6 downstream in the paper transport direction and to form a constant layer of the coating liquid 6 on the surface of the paper 3. Is provided. A dam plate 8 is provided upstream of the chamber 4 in the paper transfer direction for the purpose of blocking the coating liquid 6 in the chamber 4.

Further, as shown in FIGS. 4 to 6, when a coating solution is applied to a paper undercoat (precoat) and overcoat (topcoat), a combination of precoat → dry → topcoat → dry, always wet → dry. It was a repetition. 4 to 6, reference numeral 10 denotes a short dowel coater head, 11 denotes a hot air dryer, 12 denotes a paper feed roll, 13 denotes a take-up roll, and 14 denotes a β-ray for measuring the basis weight of paper. Note that there are various combinations in FIGS. 4 to 6, which are shown in Table 1.

[Table 1] And indicate the one side and the opposite side of the paper, respectively.

[0004]

As shown in FIGS. 4 to 6, when the precoating (undercoating) and the topcoating (overcoating) are repeated by a conventional coating method, four coating units and four drying units are provided each. This necessitates a large amount of space and increases the investment cost (initial cost).

The present invention has been proposed to solve the above-mentioned conventional problems.

[0006]

SUMMARY OF THE INVENTION Accordingly, the present invention is a method for continuously applying an undercoating and topcoating coating solution on a web surface, wherein the solids concentration is 67 to 75 wt%. And a solid content concentration of 65 to 70 wt% is used for the overcoating solution, and the solid content concentration of the undercoating solution is made higher than the solid content concentration of the overcoating solution. Using a short dowel coater head , apply the top coat coating solution to the short dowel coater without drying the previously applied undercoat solution.
It is applied without using an applicator roll using a pad , and then dried, which is used as a means for solving the problem.

[0007]

The web is wrapped around the backing roll 2 and transported, and the undercoating coating liquid is applied on the backing roll with the undercoating coater head, and then continuously dried on the backing roll with the overcoating coater head without drying. After applying the coating liquid for top coat, it is dried using an infrared dryer.

[0008]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of a first embodiment of the present invention; FIG. First, FIG. 1 shows that the coater head 10a for undercoating and the coater head 10b for overcoating are installed on the backing roll 2, and undercoating is performed on the web 3 with the coater head 10a using the undercoating coating solution, and then the drying process is performed. Subsequently, overcoating is performed using a coating liquid for overcoating with the coater head 10b, and then drying is performed with the infrared dryer 9.

As a result of various tests, the present inventors have conducted an overcoating on an undercoating and then dried both at the same time. In the case of the lightweight pre-coating of 12 g / m ² pieces, it was found that a coated product similar to the conventional one could be obtained. However, the solid content concentration of the undercoat liquid is 67 to 75 wt %, the concentration of the overcoat liquid is 65 to 70%, and if the undercoat concentration is not high, the overcoat liquid is good as the undercoat liquid. Not applied to

Referring to FIG. 1 in a concrete example, two short dowel coater heads 10a and 10b are installed on a backing roll 2 having a diameter of 1270 mm.
After performing the undercoating and the overcoating, both were simultaneously dried in the infrared dryer 9. Tables 2 and 3 show the coating liquid compositions at the time of undercoating and overcoating.

[Table 2] (Undercoat) ┌───────────┬────┬────┬────┐ │CaCO ₃ │100 │100 │100 │ │LATEX │ 6 │ 6 │ 3 │ │ phosphate esterification │ ─ │ 6 │ ─ │ ├───────────┼────┼────┼────┤ │ solids concentration ( wt %) │ 67 │ 67 │ 67 │ │ Coating amount (g / m ² ) │ 11 │ 11 │ 11 │ └───────────┴────┴────┴─ ───┘

[Table 3] (Overcoat) ┌───────────────┬────┬───┬───┬──┐ │CaCO ₃ │20 │20 │20 │ 29│ │CLAY │ 80 │80 │80 │80│ │ LATEX │11.5│ 8 │11 │ 8│ │phosphate esterified starch (A) │ ─ │ ─ │ ─ │ 4│ │phosphate esterified starch (B) │ ─ │ 4 │ ─ │ ─│ │CMC │ 0.5│ │ │0.5│ ─│ ├───────────────┼────┼─ │ │ solids concentration ( wt %) │ 66 │ 66 │ 67 │ 65 │ │ coating amount (g / m ² ) │ 11 │ 11 │ 11 │ 11 │ │ ────────────┴────┴───┴───┴──┘

Next, the embodiment of FIG. 2 will be described. This is a case where two backing rolls 2, 2 'are provided and coater heads 10a, 10b are respectively installed.
Tables 4 and 5 show the coating composition at the time of top coating and undercoating in FIG.

[Table 4] (Undercoat) ┌───────────────────┬─────┐ │CaCO ₃ (70% <2 μm) A│100││CaCO ₃ (90% <2 μm) B│100││CaCO ₃ (95% <2 μm) C│100││latex or starch│6-8│８ │ │ solid concentration ( wt %) │ 65-72 │ │ coating amount (g / m ² ) │ 6-10 │ └──────────── ───────┴─────┘

(Table 5) (overcoating) ┌────────────────────┬─────┐ │ CaCO ₃ (70% <2 μm) A │ 95 │ │ CaCO ₃ (90% <2 μm) B│95││CaCO ₃ (95% <2 μm) C│95││CLAY│5││ STARCH│3-5││LATEX│8-12│├────── │ │ solid concentration ( wt %) │ 69-70 │ │ coating amount (g / m ² ) │ 8-10 │ └ ────────────────────┴─────┘

[0012]

As described in detail above, the present invention provides
Use short dowel coater head for coating liquid
Is used as an application method for the top coating liquid.
There is no need to use cater rolls and therefore a uniform coating
The coating speed range where the quality can be obtained is set to the high speed side (~ 1200m /
min). The present invention also provides
Short dowel coater is used as the coating means for the top coating liquid.
By using a pad, the device configuration is simple and compact.
Can be used, so the undercoating
Secure space to use Todowel Coater Head
It becomes possible. This allows the coating liquid to be applied to the base paper
Can be concentrated below the backing roll.
Overflow of liquid, which is a concern in undercoating coating liquid equipment
-Smear around the equipment due to scattering,
This makes it possible to suppress such problems. Also book
The invention provides a "concentration" of the overcoat and undercoat coating solutions of 67 to 7
5 wt% and 65 to 70 wt%. Here,
"Degree" and "viscosity" are always the same or proportional
Not the thickener and binder type
The relationship between them changes. For example, in the case of high concentration coating liquid
In order to avoid extreme thickening, the amount of binder such as starch
And may reduce viscosity. In the present invention,
Using a short dowel coater head for coating
Therefore, there is no viscosity range restriction on the coating equipment,
Ensure proper printing quality of coated paper, etc.
To increase the amount of binder, and as a result
Viscosity can be higher than higher-concentration primer coating fluid viscosity
There is also. Accordingly , simultaneous drying of the undercoat and the top coat is possible, and the number of hot-air dryers can be reduced. Instead, an infrared dryer can be used, and the space can be significantly reduced as compared with the conventional case. Also, by reducing the number of dryers, the initial cost can be significantly reduced. Further, when the physical properties of the paper were compared with those of the conventional method, almost the same results were obtained as described below. (Physical properties of paper) (Conventional method) (Invention) Whiteness (%) 84.0 83.5 Opacity (%) 88.5 89.5 Air permeability (sec) 4.000 4.300.0 Smoothness Degree (sec) 2.500 2.300.0 Blank gloss (%) 64 60.0 Print gloss (%) 71 74.0 Ink set (min) 3.0 3.0 K & N ink acceptance rate (%) 10. 0 10.0

[Brief description of the drawings]

FIG. 1 is a side view of a coater for performing a coating method according to a first embodiment of the present invention.

FIG. 2 is a side view of a coater that performs a coating method according to a second embodiment of the present invention.

FIG. 3 is a side view of a conventional short dowel coater.

FIG. 4 is an explanatory view showing a conventional double-sided two-step coating process.

FIG. 5 is an explanatory diagram showing a process of two-sided two-stage coating different from the conventional process shown in FIG. 4;

FIG. 6 is an explanatory view showing another conventional double-sided two-step coating process.

[Explanation of symbols]

 2 Backing roll 3 Web (paper) 9 Infrared dryer 10a Coater head for undercoating 10b Coater head for overcoating

──────────────────────────────────────────────────続 き Continuation of the front page (72) Hiroto Young Inventor Hiroshima Research Institute, Hiroshima Research Institute, Hiroshima City 4-6-1-22 Kannon Shinmachi, Nishi-ku, Hiroshima (56) References JP-A-4-313360 (JP, A) JP-A-2-15079 (JP, A) JP-A-63-80879 (JP, A) JP-B-40-1857 (JP, B1) (58) Fields investigated (Int. Cl. ⁶ , DB name) B05D 1 / 26-1/36 B05D 7/00 D21H 23/70 B05C 5/00 101 B05C 5/02

Claims (1)

(57) [Claims] 1. A method for continuously applying an undercoating and overcoating coating solution on a web surface, wherein the solid content concentration is 67 to
75 wt% undercoating coating solution and solid content concentration of 65 to 70
Using the wt% of the top coat coating solution, and the solid concentration of the subbing coating solution was higher than the solid concentration of the overcoat coating solution, firstly short de well coater heads an undercoat coating solution
Was applied using a draw, then without drying the applied undercoat coating solution above, the overcoat coating solution in the coating solution on sucrose
Applicator roll using a coated dowel coater head
A coating method characterized in that the coating is performed without using a coating and then dried.