JPS6285095A - Production of cast coat paper - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION (A) Industrial Application Field The present invention relates to a method for producing cast coated paper, and in particular to a method for producing cast coated paper with excellent printability and high gloss at high speed. It's about law.

(B) Conventional technology Conventionally, the method of press-contacting a coating layer mainly composed of pigments and adhesives to a mirror heated surface to achieve a glossy finish has gradually improved the drawbacks of the prior art, but none of them have achieved the desired result. The effect is not fulfilled. For example, a wet casting method (for example, Japanese Patent Publication No. 28-3407, Japanese Patent Publication No. 3407, Japanese Patent Publication No. 3407, 38-25160), there is a lot of moisture in the coating layer, and it takes a long time to dry.In order to avoid boiling of the moisture in the coating layer, the drum surface temperature was set to 80 to 90℃.
It has the disadvantage that it has to be limited to ℃ and is forced to operate at low speed. Gelling casting method in which the wet coating layer is brought into contact with a gelatinizer bath to form a gel and is pressed against the mirror drum surface (for example, Japanese Patent Publication No. 38 1575"H%, Japanese Patent Publication No. 4 O-
y72o7@, U.S. Patent No. 3377192, JP-A-51
-4.0410), the coating layer is relatively strong, so
＞The speed can be increased because the coated layer is not destroyed even if it is pressed against a drum heated to J1 point or above, but the base paper is removed while passing through the nip between the drum and pressure roll to remove a large amount of moisture in the coated layer. It is necessary to move it into the layer. Otherwise, it will boil explosively after passing through the nip, and the drum will separate from the surface and will not produce a good coated paper, resulting in the disadvantage that the operating speed must be reduced. Once the wet coating layer is dry, it is contacted with the re-wetting liquid 'C5t! The rewet casting method (for example, US Pat. No. 2,759,847M)
, Special Publication No. 45 32767@, Special Publication No. 48-38005
No., JP-A No. 51-102111), the coating layer is dense and has excellent gloss even with ordinary adhesive m, and only the surface of the coating layer is re-wetted and plasticized. Therefore, there is less evaporated water and the drying speed can be increased, but
The degree of plasticization of the coating layer is rather low, resulting in poor adhesion to the heating drum. Therefore, when operating at low speeds, homogeneous, highly glossy paper can be obtained, but at high speeds, pinhole-like spots and uneven gloss appear.

(C) Problems to be Solved by the Invention The problem with the rewet casting method is that it is difficult to create an appropriate plastic state that maintains close contact with the heating drum.
In reality, sufficient rewetting fluid is supplied to obtain sufficient plasticity.
In addition, in order to avoid destruction of the coated layer due to rapid boiling of water, the drum is operated within a drum temperature range of ε30 to 95°C, but there is a limit to the speed.

(17) Means for Solving the Problems The inventors of the present invention have conducted extensive research on ω1 in order to solve the problems of the rewet casting method, which seem to be a series of problems, and have discovered the following cast paper manufacturing method. The invention was completed.

That is, the coating layer containing pigment and adhesive as main components is re-wetted,
In the manufacturing method of cast-coated paper, which is produced by press-contacting a heated specular drum for a high-gloss finish, the heated specular drum is moistened with warm water of 90°C or higher in the nip between the press roll and the wetting time is 30 mm. It is characterized in that the temperature of the mirror drum is 95° C. or higher. In the method of the present invention, pigments used in the coating composition include general pigments such as clay, phosphorus, aluminum hydroxide, calcium carbonate, titanium oxide, barium sulfate, zinc oxide, zatin white, and plastic pigments. Pigments used in coated paper are used, and adhesives include styrene-butadiene latex, synthetic latex such as polyvinyl alcohol, strength in, proteins such as soy protein, oxidized starch, cationic starch, and phosphate esterified starch. Adhesives used for general coated paper, such as starches such as

Roughly speaking, since the present invention performs instantaneous rewetting with high-temperature water, the strength of the coating layer is required, but this is especially required when the coating layer is applied continuously until Cast 1. I become strict. When this property is to be provided by an auxiliary agent, a water-resistant agent that is particularly fast-acting is particularly effective in terms of effectiveness. The water resistance agent used is not particularly limited, but silconic carbonate/cumammonium, formalin, urea resin, melamine resin, acrylamide resin, etc. can be used. In addition, alkaline substances such as ammonia and amines, alkalis, acids and salts such as sodium chloride, ammonium chloride, alcohol penta-acid and potassium tartrate, aldehydes, phenols and their ═S forms may also be used as appropriate.

Antifoaming agents, coloring agents, mold release agents, etc. can also be used as other auxiliary agents.

The coating composition thus prepared can be coated with a blade coater or an air knife, which are commonly used in the production of coated paper.
The base paper is coated in one layer or in multiple layers using a roller coater, barter, etc.

The coated composition is dried using a conventional coated paper drying device such as a hot air dryer A7-, an air foil dryer, an air cap dryer, a cylinder dryer, or an infrared dryer.

According to the conditions of the present invention, it is finished to -C cast], which is particularly effective for casting at high temperatures and high speeds.

The re-wetting liquid is not particularly limited, and ordinary re-wetting liquids such as polyethylene emulsion, fat-resistant GK, calcium stearate and surfactant can be used. Further, in order to eliminate uneven adhesion, it is also possible to use an alkali, sodium hexametaphosphate, etc. in combination.

(E) Effect Regarding the causes of the effects of the present invention, the conventional I
This becomes clear when compared with the Nowetcast method. Conventionally, in order to give the coated layer sufficient plasticity before it enters the nip between the mirror drum and the pressure roll, rewetting liquid is brought into contact with the coating at a location away from the nip, which reduces the strength of the coated layer at the time it enters the nip. It became weak, and it was necessary to lower the drum temperature to below 100°C. In addition, even when rewetting with nip water only, prevent the nip water from boiling and keep the drum temperature below 100°C.
I was driving at a reduced speed.

In contrast, in the present invention, the amount of water in the nip is reduced as much as possible, the passage time of the nip water is 30 milliseconds or less, rewetting is instantaneously performed using high-temperature water at 90°C or higher, and drying is performed using a drum at 95°C or higher. As a result, cast-coated paper with good printability and no pinhole-like spots or uneven gloss can be obtained at high speed. If the passage time of the nip water is longer than 30 milliseconds, wetting becomes excessive, which weakens the strength of the coated layer and affects the surface condition of the cast paper.

In addition, since rewetting in the present invention is carried out using high-temperature water C, by using a fast-acting waterproofing agent in the coated layer, destruction of the coated layer can be prevented and cast paper with a good roughness can be obtained. .

(F) Examples Examples of the present invention are shown below, but the invention is not limited thereto. Further, parts and % in the examples represent parts by weight and % by weight, respectively.

Examples 1 to 5, Comparative Examples 1 to 4 80 parts of kaolin, 20 parts of light calcium carbonate, and 0.5 parts of sodium polyacrylate were dispersed in water using a "-less dispersion method" to form a pigment slurry with a solid content concentration of 60%. Prepared. To this were added 15 parts of styrene/butadiene copolymer latex, 0.1 part of 1 helibutylene sulfate, 1 part of ammonium oleate, and 10 parts of an ammonia-dissolved casein aqueous solution in solid form, and then added water to increase the solid content concentration. A 48% coating solution was prepared.

Ammonium zirconium carbonate and ammonium chloride were added to the resulting coating solution as shown in Table 1 to prepare a coating solution with a finished solid content of 42%. Coating liquids containing neither ammonium zirconium carbonate nor ammonium chloride are prepared by adding water to adjust the solids content to 42%.

The obtained coating liquid was used for rewetting and spraying.

The equipment used was an air knife coater, a dryer, and a distance 2 m from the nip between the pressing drum and the pressure roll.
There is a roll coater for rewetting at a separate location, followed by a rubber roll with a diameter of 400IlIIn and a chrome-plated cast drum with a diameter of 1000mm, and a nozzle is located on the nip formed by these, from which the rewetting liquid is supplied. be done.

Table 1 shows the hanging and casting conditions for the waterproofing agent and the paper quality evaluation results.

(G) Effects of the Invention The present invention applies to the nip between the specular drum and the pressure roll at 95°C or higher after drying the coating layer mainly composed of pigments and adhesives.
By moistening in a short time of 30 milliseconds or less with hot water above 0°C and applying the coating to KiX-S1, it is possible to achieve a coating with better gloss and printability than the conventional Cast-1 method. It is possible to obtain paper at high speed.

Claims (1)

[Claims] In the method for manufacturing cast coated paper, a coating layer mainly composed of pigments and adhesives is dried, then moistened, and pressed against a heated mirror drum to give a high gloss finish. A cast-coated paper characterized by being moistened with hot water of 90°C or higher between the nip with a pressure roll, the wetting time being 30 milliseconds or less, and the temperature of the specular drum surface being 95°C or higher. Production method.